L~OLVENT REFINED COAL AND COAL-OIL MIXTURES/

A Thesis presented to

The Faculty of the College of Engineering and Technology

Ohio University

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

by

Avant! E-mbalia;

June 13, 1981 ACKNOWLEDGEMENTS

The author wishes to thank his advisor, Professor Robert L. Savage, for his advice and guidance in bringing this work to a successful com­ pletion. The author wishes to thank the Pittsburgh Midway Coal Mining

Company of Dupont, Washington for supplying SRCI and SRCII samples.

Finally, the author also wishes to thank Louella Rich and Diana Miller at the Word Processing Center of The Standard Oil Co, Cleveland, Ohio, for the typing of this thesis. TABLE OF CONTENTS

PAGE

INTRODUCTION 1

COAL-OIL MIXTURES 6

Coal-Oil Mixture Technology 6

Stability of Coal-Oil Mixture 7

Testing Procedures Used for Stability Study 8

Density of Coal-Oil Mixture 11

COAL LIQUEFACTION 12

Relations of Coal and Solvent for Extraction 13

Variables Important for Extraction 17

SRC Technology 19

OBJECTIVES 23

EQUIPMENT AND EXPERIMENTAL PROCEDURE 25

Stability Study 25

Viscosity -and Density Measurements of Coal-Oil Mixtures 38

Coal-Oil Mixture Sample Preparation 41

Preparation of Low-Ash Coal 43

Apparatus 47

RESULTS AND DISCUSSION 50

Stability Studies 50 TABLE OF CONTENTS (Cont'd)

PAGE

Coal Concentration with Height 72

Tuned Circuit Detector 90

Viscosity of Coal-Oil Mixtures 104

Density of Coal-Oil Mixtures 117

Low-Ash Coal 121

CONCLUSIONS 130

RECOMMENDATIONS 132

REFERENCES 134

Appendix A- Derivation of the formula used for the A1-A4 pendulum

Appendix B- Procedure used for the percent solids BI-B2 determinations in coal-oil mixtures

Appendix C- Proximate, ultimate, sulfur and ash analysis CI-C2 for the coal used

Appendix D- Settling data DI-D9

Appendix E- Data for a metal detector EI-EIO

Appendix F- Viscosity data for COM F1-F8

Appendix G- Viscosity data for SOM GI-G5

Thesis Abstract LIST OF FIGURES

FIGURE PAGE

1 Pendulum Apparatus used in Determining Settling in

Coal-Oil Mixtures 26

lA Sketch of Pendulum Apparatus 27

2 The Arrangement used for Fixing Settling Tube

inside the Carriage 28

3 Settling Tube with Block inserted at the

Carriage Bottom and Timer Contacts 28

4 Sketch of Coal-Oil Mixture Column 33

5 A Metal Detector used for Stability Study 36

6 Circuit for a Metal Detector 37

7 Dissolver for Preparation of Low-Ash Coal 44

8 Size Distribution for No. 8 Coal 53

9 Size Distribution for Solvent Refined Coal 55

10 Stability of Suspensions: Curves showing

the Relationship between C.G. drop and Time 60

11 Pendulum Error Analysis: Thread Number

vs. Time Period 68

12 Pendulum Error Analysis: Thread Number

vs. Deviation in Time Period 68 LIST OF FIGURES (Cont'd)

FIGURE PAGE

13 Pendulum Error Analysis: Thread Number vs.~T/~T 71

14 Coal Concentration versus Height 76

15 Coal Particles at Top of Tube, 1 day after

the Mixture Preparation 78

16 Coal Particles at Bottom of Tube, 1 day after

the Mixture Preparation 78

17 Coal Particles at Top of Tube, 24 days after

the Mixture Preparation 79

18 Coal Particles at Bottom of Tube, 24 days after

the Mixture Preparation 79

19 Relationship between C.G. drop and Coal Content 81

20 Coal Particles at Top of Tube, 12 days after

the Mixture Preparation 86

21 Coal Particles at Bottom of Tube, 12 days after

the Mixture Preparation 86

22 Coal Particles at Top of Tube 32 days after the

Mixture Preparation 89

23 Coal Particles at Bottom of Tube, 32 days after

the Mixture Preparation 89 LIST OF FIGURES (Cont'd)

FIGURE PAGE

24 Curves for an Original Circuit 91

25 Curve for NO. 6 oil at 25°C. 93

26 Curve for 40% COM, after 1 hour 94

27 Curve for 40% COM, after 8 hours 95

28 Curve for 40% COM, after 2 days 96

29 Curve for Glycerine, liquid level I" above the

top coil 99

30 Curve for Glycerine, liquid level 4" above the

top coil 100

31 Curve for a Viscosity Standard 102

32 Viscosity versus Percentage Coal 112

33 Log-log plot of Apparent Viscosity versus Spindle

Speed 113

34 Thixtropy: Dial readings versus Spindle Speed for

Coal-Oil Mixtures 116

35 Variations in Density of Coal-Oil Mixtures 120 LIST OF TABLES

TABLE PAGE

1. Extraction of Bituminous Coal by Aromatic

Compounds 15

2. Dry Sieve Analysis for No. 8 Coal 51

3. Dry Sieve Analysis for solid Solvent Refined Coal 52

4. Coal-Oil Mixture Compositions used for Stability

Studies 56

5. Settling Data for COM 57

6. Settling Data for SOM and Low-ash coal-oil mixtures 58

7. Pendulum Reproducibility Data (Standard tube) 64

8. Pendulum Reproducibility Data (Tube with No. 6 Oil) 65

9. Error Analysis for the Pendulum (data) 67

10. Error Analysis for the Pendulum 70

11. Variation in Coal Concentration with Height 74

12. Variation in Coal Concentration with Height 85

13. Variation in Coal-Oil Mixtures Viscosity with the

Coal Content 111

14. Thixotropic Behavior of Coal-Oil Mixtures 115

15. Density of Coal, Oil and Coal-Oil Mixtures 118

16. Preparation of Low-ash Coal (using phenanthrene) 122

17. Preparation of Low-ash Coal 127 INTRODUCTION

World demand for energy is increasing at a dramatic rate, and this trend is unlikely to change in the foreseeable future. Because a combination of economic, technological and ecological pressures are preventing atomic energy from meeting any significant portion of the demand, the major energy sources continue to be oil, coal and natural gas. Projected limitations on supplies of domestic oil and natural gas, and the need to reverse the country's increasing reliance on foreign petroleum sources, are stimulating consideration of America's vast coal deposits as a way of satisfying more of the nation's energy

requirements.

Several technologies to convert coal to various synthetic fuels are being developed in the United States, some with support from the

U.S. Department of Energy. Commercial coal-gasification and demon­

stration coal-liquefaction plants are proposed(l). Many existing

gas and oil fired electric power plants are designated candidates for

coal-boiler conversion in accordance with power plant and Industrial

Fuel Act of 1978. Substantial economic incentives exist to convert

coal to liquid and gaseous fuels, since most energy using devices

require such fuels.

Coal Liquefaction

The term "liquefaction of coal" refers to any method (other than

carbonization of coal for coke) by which all or part of the coal is 2

converted to liquid form. The advantage of coal liquefaction, over other coal conversion processes is that the entire range of liquid products, including fuel oil, gasoline, jet fuel and diesel oil, can be produced from coal by varying types of catalyst and operating conditions. Furthermore, coal-derived liquid fuels have potential for use as a chemical feed stocks (2).

The u.s. Department of Energy program for the conversion of coal to liquid fuels was started by its predecessor agencies: Energy

Research and Development Administration (ERDA), Office of Coal

Research (OCR) in 1962, and Bureau of Mines, U.S. Department of the

Interior, in the 1930's (2). Techniques for converting coal to synthetic liquid fuel, originally developed in Germany in the early

1930' s , are being improved to increase the supply of non-polluting liquid fuel to produce a more easily transportable and usuable fuel.

Current emphasis is on the development of fuels suitable for firing industrial and electric utility boilers and gas turbines.

Some of the coal liquid production processes are: Consolidation

Coal Company CSF process, PAMeO Solvent-Refined Coal, H-Coal process,

Char-Oil Energy Development (COED) process, Seacoke process by

Atlantic Richfield Company and Bureau of Mines Synthoil process.

These processes are currently in different stages of development.

Solvent Refined Coal

The PAMCO solvent refined coal process was developed by the

Pittsburgh and Midway Coal Mining company (formerly Spencer Chemical 3

Company). The primary objective of the process is to produce a low-ash low-sulfur fuel which can be fed to a boiler in either solid or liquid form. Solvent Refined Coal (SRC) meets any existing and proposed EPA regulations and it can be considered as an attractive potential fuel.

Two major government funded projects are in progress for the development of Solvent Refined Coal. At present SRC is produced by two different methods known as SRC I and SRC II (4,5).

In short, SRC I involves solution of most of the coal in a donor solvent derived from the process, separating the undissolved solids by filtration, distilling of the original process solvent and recovering the dissolved coal as a solid material known as SRC I.

SRC II is an advanced coal-liquefaction process, in which coal is mixed with the portion of the product slurry and hydrocracked to liquid and gaseous products. The dissolved coal unconverted to distillate fuel and lighter product is sent to a gasifier, together wi th the undissolved mineral residue, to produce hydrogen for the process. Thus, a solid liquid separation step is not required and the primary product from SRC II process is distillate fuel oil.

The present work includes a laboratory investigation of some alternate method--other than conventional SRC process, for the preparation of a low-ash coal. Motivation for the problem came from

(1) the project "A Study of the Potential Use of Solvent Refined Coal in Ohio" at Ohio University, sponsored by Ohio Air Quality Development

Authority and (2) a Bituminous Coal Research, Inc. report on the 4

preparation of low-ash coal by solvent extraction based on research

conducted for North American Coal Corporation in 1959.

Coal-Oil Mixtures

A coal-oil mixture (COM) is an alternative fuel, prepared by

dispersing pulverized coal into residual fuel oil. The basic concept

is to pulverize the coal, mix it with residual fuel oil,' and then

feed it directly to an existing oil or gas fired boiler with a minimum of modification to the boiler.

Coal-oil mixtures are expected to have potential to displace

petroleum-based oils in many segments of the energy market. The

primary applications are expected to be in retrofit of oil designed

combustion facilities which have only oil handling equipment and for

which conversion to firing of coal powder is undesirable. The recent

Second International Symposium on coal-oil mixture combustion (6)

indicated a widespread activity on COM and a readiness for the

technology to enter the market, both in the United States and

Internationally.

In the medium term, solid Solvent Refined Coal (SRC I) - fuel oil

and SRCI - SRC II mixtures will be able to fulfill certain specific

needs for which COM is less suitable. SRC I-Oil mixtures (SOM) would

be the preferred choice in those applications where COM is technically

feasible but expensive capital costs (such as for boiler modification)

are required or where COM is not technically feasible due to sulfur

or ash content. 5

SOM may make some applications technically feasi b.le , because of the low mineral ash, which are not available to COM. Based on similar reasons, there is a very good possibility that low-ash coal produced by solvent extraction can be mixed with industrial fuel oil, which would result in an environmentally acceptable fuel. A low-ash coal­ oil mixture may have an application where SOM is expensive to use and

COM is not technically feasible. Both SOM and low-ash coal-oil mixtures are seen as the next stage after near-term d.evelopment of

COM (7).

The basic problem with a coal-oil mixture is the suspension stability. The coal-oil mixture should be stable enough for long-term storage in tanks designed for liquids, otherwise on-site solids grind­ ing and slurry mixing equipment will be required. The energy required to recirculate or continuously mix a coal-oil mixture for long storage periods is small but the equipment modifications and operating procedure changes are significant (7).

The present work undertakes a preliminary study of the stability and rheological properties of 50/50 coal-oil mixtures (COM) and com­ pares those to similar properties of SRC I-Oil Mixtures (SOM) and a low-ash coal-oil mixture. The motivation for this problem came from

(1) possibility of using a 50/50 mixture of low-ash coal-oil mixture as an economically and environmentally acceptable fuel, (2) a project sponsored by the Ohio Department of Energy for COM utilization in small industrial and commercial boiler, at Ohio University, Athens,

Ohio. COAL-OIL MIXTURES

A coal-oil mixture is an alternative fuel, prepared by mixing powdered coal into residual fuel oil. The idea of a coal-oil mixture is not new, however, it resurfaced recently due to current emphasis on lessening the dependence on foreign oil.

Coal-Oil Mixture Technology

Extensive laboratory and field tests on coal-oil mixtures were done in 1944 by Barkley, et. al. (8) as the result of a joint effort by the Federal Bureau of Mines and the Atlantic Refining Company of

Philadelphia, Pennsylvania. The pioneer of recent coal-oil mixture combustion work was General Motors who demonstrated coal-oil mixture utilization in a 120,000 pph industrial boiler designed for oil and gas (9). The project was an overall technical success, however, some problems were identified. Further testing of coal-oil mixture combustion in industrial boilers has been done by the Department of

Energy at the Pittsburgh Energy Technology Center using a 700 hp oil-fired boiler. Additional coal-oil mixture demonstrations in industrial boilers have been done by the steel companies. Several other electric power companies have also demonstrated long-term and short-term feasibility of coal-oil mixture combustion in industrial boilers (10). 7

Various investigators have studied the stability and flow characteristics, as well as atomization and combustion of coal-oil mixtures. Those studies also include the performance of grinding

equipment, pumps, burners and instrumentation with coal-oil mixtures. Due to increased demonstration and commercialization

activities for coal-oil mixtures, most of the hardware already exists

but a research and development effort must continue to get an insight

into this complex fuel system.

Stability of Coal-Oil Mixture

The basic problem with coal-oil mixture is the suspension

stability. It is desirable to find mixtures which would have more

suspension stability for use as a substitute fuel for oil in utility

and industrial boilers.

"Stability" is a relative term and no coal-oil suspension is

perfectly stable. The stability decreases with decrease in coal

content or fineness and with increase in temperature. Stability also

depends on the nature of the coal and nature of the oil used (8).

Botsaris, et. ale (11) indicated the importance of the surface

properties of coal used in relation to stability and rheological

properties of coal-oil mixture.

From Stokes Law, it can be said that suspension stability will

increase by using coal of low specific gravity and oil of high

specific gravity and viscosity. It is also evident that suspensions

of high coal content will be more stable than those of low content 8

because of hindered settling. The actual conditions for settling in concentrated suspensions are complex. Such suspensions develop rigidity for high solids content. Coal-in-oil suspensions have been shown to develop this rigidity in the neighborhood of 38 volume percent coal (12).

For finely divided coals in heavy fuel oils, the viscosities of the suspension were found to rise markedly in the region of 40 to 50 percent of coal by weight (8). This rapid rise in viscosity in the range of 40 to 50 percent of coal was found to be relatively indepen­ dent of the viscosity of the oil and the temperature of measurement.

These suspensions were also found to be non-Newtonian, i.e., the viscosity varied with the rate of shear, this deviation from viscous flow resulting from the development of structure in the suspensI on

(8). These suspensions were found to be thixotropic in nature, a much higher apparent viscosity was observed on the first pass of the

T-bar spindle. A log-log plot of average apparent viscosity VB. viscometer spindle speed was found to be a straight line for such suspensions (13).

Testing Procedures Used for Stability Study

Because visual observation of settling is not practical with heavy fuel oils, the solids settling must be determined by indirect means. Since a number of heterogeneous samples must be tested on a daily basis, a nondestructive reproducible technique must be employed. 9

Settling stability of coal-oil suspensions has been studied by measuring the change in center of mass of the suspension by means of a compound pendulum device (7,8,14). In such a system, the center of mass of the slurry is determined by accurately measuring the time period. The change in center of mass of the suspension can be correlated wi th the percentage of settling that has occurred. An attempt made by Barkley, et. a1. (8) suggests that complete settling of coal can be determined in an ethanol-water solution having the same specific gravity as oil. Assuming the net effect of sedimentation is the gradual change in concentration of the slurry, a

linear relationship between the change in center of mass and percentage of settling can be used. Accumulated studies with coal-oil mixture at Adelphi Research Center (14) indicates that any

slurry whose center of mass shifted not much more than 1 mm, does not

present a problem in pumping and combustion of such fuel. A much

larger shift in center of mass represents a significant increase in viscosity at the bottom of a storage tank. A pendulum method has

also been employed to predict settling velocities of coal particles

in heavy 011 (15).

T. T. Coburn (13) suggests that viscometry is a convenient method

for detecting settling. He used the relation of the form

Log (Apparent Viscosity) - a Log (Spindle Speed) + b

and indicated that change in value of "a" (slope of the curve) with

depth in a coal-oil mixture column can be related to the percent

solids present. It is also concluded that the variation in viscosity 10

with depth is a reflection of weight percent coal solids and not merely an indication of particle size non-uniformities or some other factor. A Brookfield viscometer with a "T" shaped spindle has been employed to obtain viscosity profiles (13). Such a viscometer, with a helipath device attached, moves the viscometer head continuously up or down through the slurry while taking dial readings.

Another method based on viscosity measurement is the "rod penetration" method which is more popular in Japan (16, 17). A rod of definite shape and weight is dropped on the coal-oil mixture sample, the time required for the rod to reach the bottom of the sample is measured. According to the degree of settling and compacting of the coal particles in a coal-oil mixture, the penetration time differs. The relative stability of the coal-oil mixture can be determined by measuring the penetration time.

Other methods employed measuring settling rates are more direct ones. (1) Small samples removed from the coal-oil mixture column from various heights and analyzed for coal concentration, (2) a removable disk is placed at the bottom of 8 beaker containing a coal-oil mixture and the material adhering to the disk is examined periodically, and (3) freezing of the coal-oil mixture sample tube and analyzing each section of the tube for coal content, gravimetrically. 11

Density of Coal-Oil Mixtures

The density of the mixture has been determined using a Hubbard type pycnometer. It shows the expected variation with temperature.

The actual change in density with temperature is relatively small--one percent change with a 20°C temperature change. The specific gravity of a mixture can be calculated from an expression of the form (13).

-1 (Spec. Grav.) % wtj 100 x (Spec. Grav.)!

where, % Wti = percent by weight component i and

(Spec. Grav.)i = specific gravity of component i. COAL LIQUEFACTION

The term "liquefaction of coal" refers to any method (other than carbonization of coal for coke) by which all or part of the coal is converted to a liquid form. A wide variety of techniques can be used, at least on a laboratory scale. These include direct contact of pulverized coal with hydrogen, as well as dissolution techniques wherein the coal is partially dissolved by a suitable liquid solvent.

Practical aspects of coal liquefaction process were emphasized during

World War I by the Germans in the development of the Pott-Broche extraction process (18). This work resulted in the discovery of very efficient solvents for the pressure extraction of coal.

Solvent refining is one of the more attractive means for converting coal into liquid fuels and various aspects of liquefaction processes have been studied extensively (19). The studies have varied widely, ranging from rate determinations utilizing several types of coal and of donor solvents to attempts to identify the composition of specific fractions of the product (20, 21, 22, 23).

Two of the reviews on coal liquefaction, used as a basis for this survey are: M. W. Kiebler (24), and I. G. C. Dryden (25, 26). The reviews include most of the papers on solvent extraction up to 1950.

After the 50' s the trend in solvent extraction studies shifted to instrumental applications having the emphasis on the constitution of a coal. 13

Relations of Coal and Solvent for Extraction

1. Nature of Coal:

Petrographic analysis of coal has been used in relation to

extraction. Stopes (27) in 1919 used nomenclature which is based

on the visual examination of coal. Dull, hard zones are durain;

shiny, fragile zones having appearance of black glass are vltrain;

shiny banded zones in bright coals are clarain; and fibrons

appearing zones are fusain. Generally, vitrain is attacked by

solvents and goes into solution. At high temperatures in the

range of 350 to 40QoC, almost all of the virtrain will be placed

in solution in both pyridine and benzene type solvents. However,

fusain is for all practical purposes insoluble. It is also

expected that extraction will vary with the carbon and oxygen

content of the coal (28).

Considerable effort has been given to the development of

structural models for coal. Kreulen's (29) Micellar model simply

illustrates surface tension effects, temperature and rank of coal

influence' the extraction yields common to most solvent-coal

systems. In spite of the extensive effort given to coal

characterization, no one can yet specify what a "coal molecule"

is (28).

2. Nature of Solvent:

Two types of solvents used are "pyridine" type and "benzene"

type solvents. Generally, "benzene" type solvents are aromatic 14

hydrocarbons while a "pyridine" type solvent are characterized by a function atom, nitrogen in particular, having a unshared pair of electrons (30). Benzene type solvents are more temperature sensitive than pyridine type solvents. a. Benzene Type Solvent:

The primary requirement in this class of solvents is a

high boiling point. If the solvent can function as a hydro­

gen donor, then the yield is increased. If, in addition to

a hydroaromatic ring) the solvent possesses an aromatic

hydroxy group, then the solvent becomes a very efficient

extracting agent. Go1umbic, et. a1. (31) have used a number

of solvents showing the above relations (Table l). Other

works (32) report this view that extraction yields increase,

with few exceptions, with an increase in boiling point of

the solvent. b. Pyridine Type Solvent:

The mechanism for solution by these solvents has been

suggested (30). Bitumen is held within a coal micelle com­

plex and is released into solution as the structure swells.

This swelling may be accomplished by either temperature

effects or by the affinity of the electron pair to the coal

matrix or by a. combination of both. In addition to this

swelling effect, solvent adsorption also plays a role in the

action of pyridine type solvents. This adsorption tendency

has been reported for phenols, naphthol and especially 15

TABLE 1

EXTRACTION OF BITUMINOUS COAL BY

AROMATIC COMPOUNDS

SOLVENT FORMULA BOILING PERCENT PERCENT POINT, °c EXTRACTION* BENZENE SOLUBLE*

Phenanthrene 96\~ !,"= ~ jl 340 95 19

5,6-Benzoquinoline (--6~); 351 95 19

5,6-Benzoquinoline F{5J-~.I.I _ ~ IJ C:H3 352 93 25 Phenanthridine C£P 360 89 13 Carbazole qy 355 88 21 NH 9-Methyl Phenan-

I~ _~ threne o;p;, /, 360 82 17 O~ CH3 I-Naphthol 388 80 19 CO~ ~ 2-Naphthol OCTHI ~ 295 78 20 P-phenylphenol o-o- 308 78 7 9,lO-Dihydro-

_ ~!J phenanthrene ctY 307 60 22 P-Cyclohexyl-

phenol 0000 296 58 20 Fluorene G(P 295 26 11 16

TABLE 1 (Cont'd)

EXTRACTION OF BITUMINOUS COAL BY

ARO~~TIC COMPOUNDS

SOLVENT FORMULA BOILING PERCENT PERCENT POINT, °C EXTRACTION* BENZENE SOLUBLE*

Diphenylene Oxide \C~~y 288 25 15 Anthracene we~ ~ U 354 24 9 O-Cyclohexyl- HO phenol Q-{) 287 20 16

Diphenylamine O-~ 302 19 11 H'\ O-Phenylphenol Q--J(") 275 15 6 Diphenyl 0-0 255 8 3 1)4-Diphenyl-

butadiene O(I1~02.0 350 5 4

* Moisture and air-free basis. From Reference Number 31. 17

pyridine compounds (24). The nature of the pyridine

solvents may be stated as chemically non-specific. Evidence

(33) suggests that these extracts represent the smaller

colloidal units of the whole coal and that the undissolved

residue represents the larger colloidal units.

Variables Important for Extraction

1. Duration of Extraction:

The curves of time-yield studies have been classified by

several mathematical models. For a tetralin system (25), the

curves were found to follow a parabolic law up to seven hours

extraction time. Grayaznov (25) represents his work with power

expressions. Oele, et. a1. (30) use a simple differential form

in explaining their extraction system. It is quite probable that

the small yield results from a strongly retarding transfer of

coal constituents which may have been adsorbed on the residual

coal matrix.

2. Temperature:

For most classes of solvents studied, the benzene type

solvents exhibit the most marked temperature effect. Kiebler

(24) has attempted to classify the influence of temperature with

an equation:

Y - a + bPi

where Y 1s the yield, a and b are temperature dependent

constants, and Pi is the internal pressure of the solvent. He 18

found that for three different types of solvents, benzene,

aniline and pyridine, the constants a and b are nearly linear

functions of temperature up to 250°C. However, above 250°C the

increase in rate is much more rapid and the equation does not fit

the observed data. As the temperature reaches 200°C, the amount

leached from coal increases due to thermal depolymerization, and

weakening of the secondary valance or electrostatic forces.

3. Particle Size:

As a general rule, extraction yields tend to increase as the

particle size decreases. The greatest effect is shown when the

coal sized to one micron, however, the nature of the solvent

plays an important role in the above generalization. In the

higher temperature range, above 300°C, the effect of size becomes

less important (24).

Considering specific solvents and their reaction on

bituminous coal ground to micron size, Fisher, Peters and Cremer

(24) found more than a tenfold increase in the yield for their

trichloroethylene bituminous coal system. Asbury (34) also

compared micron sized coal to 60 mesh coal in a benzene system

and found that the respective yields were 20 and 16.5 percent at

the end of 100 hours contact time. Opposing this work, Dryden

(25) and Crick (35) suggest that particle size becomes less

important in pyridine type solvents. 19

It would seem that particle size must be noted for each

extractive system, but it may not be as important as temperature

or the nature of the solvent.

4. Pretreatment of Coal:

The literature considering the effects of pretreatment

(primarily preheating of the coal) of coal before extraction is

not consistent. Dryden (25) suggests that pretreatment is

dependent on the rank of coal, temperature and solvent. Several

authors have shown the value in removal of surface moisture. For

the poorer solvents, a higher temperature will be needed to give

increased yields. For the effective pyridine type solvents,

lower preheating temperatures will serve to give the higher yield.

SRC Technology

The basic technology for the SRC process was developed in Germany soon after World War I. Two German scientists, Pott and Broche (18), patented the basic process for dissolving coal and reducing its ash content in 1932.

1. Spencer Chemical Company's De-Ashing Process:

Bench scale work on the present SRC process was carried out

from 1962 to 1965 by the Spencer Chemical Company, under the

sponsorship of the Office of Coal Research of the U.S. Department

of the Interior (36).

Basically, the process involved dissolving coal in a coal­

derived solvent, anthracene. After the coal has been dissolved 20

and is in liquid state, the ash, which does not dissolve, can be

removed by filtration. The solvent is then recovered for use in

another cycle, while the fuel can either remain in a liquid state

or be converted back into a solid. Essentially all ash is

removed in the process, pyritic sulfur (in the form of iron

sulfide) is filtered out with the ash, since it is not affected

by the solvent, while organic sulfur in the coal escapes as

hydrogen sulfide. The degree of sulfur removal is expected to

depend largely upon the relative amounts of organic and pyritic

sulfur present in the coal.

2. Low-ash Coal by Phenanthrene Extraction:

The literature contains much evidence that certain organic

solvents at their boiling point and atmospheric pressure can be

used for extraction of bituminous coal. In particular, the u.s. Bureau of Mines, Report of Investigations by Golumbic, et. a1. in

1950 (31) and exploratory experiments carried out in 1959 by

Bituminous Coal Research, Inc. for the North American Coal

Corporation (37) indicated that phenanthrene was a suitable

solvent to produce low-ash coal.

H. J. Rose (38) observed that phenanthrene at its atmospheric

boiling point readily dispersed 80 percent or more of Pittsburgh­

bed bituminous coal. Work done at the Bureau of Mines confirmed

this observation and showed that it reacts irreversibly with any

portion of the coal and can be recovered quantitatively from the

extract (31). The mechanism of the dispersing action of phenan- 21

threne remains unknown. It seems probable that phenanthrene has

a selective solvent action on those constituents of coal that act

as binding agents for the micellar portion of the coal. Removal

of the binding agent material leads to disintegration of the

colloidal structure of the coal and peptization of the micelle in

the solvents (39). It is also concluded that chemical reactions

take place during phenanthrene extraction of bituminous coals

(40). The net result of these reactions is a hydrogen exchange

between the coal substance and the phenanthrene and a simulta­

neous depolymerization of the coal as evidenced by the high

extract yields. The formation of the coal extract can be

interpreted as a free radical chain reaction leading to

depolymerization of the coal and aromatization of some of the

hydroaromatic structures. It is possible that phenanthrene plays

the role of a chain carrier in an extraction process (40).

3. Advances in SRC Technology:

Over four years of successful pilot plant operation at

installations in Wilsonville, Alabama and Ft. Lewis, Washington,

have demonstrated that the SRC process has reached the status of

a proven technology. Plans are now being readied for scale-up to

a commercial size demonstration facility (4). A paper presented

by R. R. Maddocks (41) highlights an understanding of the

reaction mechanism and system behavior during solvent processing

of coal. The paper also attempts to describe the SRC process

model and process development work investigating various features. 22

SRC-II is an advanced coal liquefaction process which not only dissolves the coal, but hydrocracks into liquid and gaseous

products. Recent experience in large pilot plant operations has

proven the technical feasibility of the SRC-II process and development is underway for a 6,000 tons per day demonstration plant at Morgantown, West Virginia. The SRC-II process produces a very low-sulfur distillate fuel oil, as well as pipeline gas, naphtha and LPG by-products. Product characterization and

testing of the fuel oil indicates that it has excellent potential

for displacement of petroleum fuels in industrial and utility

boilers (5). OBJECTIVES

The purpose of this research was to investigate stability and rheological properties of coal-oil mixtures. Different types of coals such as Ohio No. 8 coal and commercial solid Solvent Refined

Coal (SRCI) were used to mix with No. 6 fuel oil for the mixture preparation.

Fifty weight percent mixtures of coal/oil were used for the evaluation of settling stability in which the particle size of the coal and temperature were varied. Studies on rheological properties of different coal-oil mixtures such as its non-Newtonian character or thixotropic behavior if any exist were investigated by using a rotational type viscometer. Also, the density measurements of such mixtures were carried out.

Experiments were also done to investigate some alternate methods

- other than commercial SRC process, for the preparation of Low-ash coal. Attempts were made to dissolve different types of Ohio coals such as No. 4A and No.8 coals in different organic solvents with varying process conditions. The dissolved coal along with solvent(s) were separated from the undissolved portion of the coal by means of filtration. The filtrate which contains Low-ash coal (dissolved material) was processed to remove solvent(s). The resultant Low-ash 24

coal was mixed with No. 6 fuel oil for the evaluation of suspension stability. Stabilities of such mixtures were compared with those of

Ohio No. 8 coal-oil and SRCI-oil mixtures. EQUIPMENT AND EXPERIMENTAL PROCEDURE

STABILITY STUDIES

1. Pendulum Apparatus:

In the laboratory, stabilities of coal-oil mixtures were

studied by measuring the shift in center of mass of the

suspension by means of the pendulum arrangement. The pendulum

design used here was similar to those used by BarkleYt et.al. (8).

The apparatus used is shown in Figure 1 and lA. The

pendulum consisted of a wooden carriage supported on a pivot. The

carriage was so designed that a glass tube containing a coal-oil

mixture can be placed into it and held in place with the help of

set screws (see Figure 3). The period of the pendulum was

measured accurately by means of electronic timer and photocell

arrangements (see Figure 4). A thin wire attached at the bottom

of the carriage acted as a pointer. Light was focused on the

pointer in such a way that it gave a very thin and dark shadow on

the photocell.

The period of this system, measured first with the tube in

its normal position inside the carriage (Tl), and then with the tube raised through a known distance referred to its support by

the insertion of a block of known dimensions (T These two 2). independent time period measurements provided a means of PENDULUM APPARATUS USED IN

DETERMINING SETTLING IN COAL-OIL MIXTURES

FIGURE 1 q 1 1 1.0. GLASS TUB E o It) FILLING MARK

SC REWS TO HOLD TUBE IN PLACE

PIVOT

STEEL SURFACE

A WOODEN CARRIAGE

STAND o (W) o C\I o (t)

65 AMPLITUDE SCALE \.. LIGHT BULB

PO NTER ~ 125--~ PHOTOCELL

ALL DIMEN,SIONS ARE IN MILLIMETERS

SKETCH OF PENDULUM APPARATUS FIGURE 1A 28

..~---

THE ARRANGEMENT USED FOR FIXING

SETTLING TUBE INSIDE THE CARRIAGE

FIGURE 2

SETTLING TUBE WITH BLOCK INSERTED AT THE CARRIAGE BOTTOM AND THE TIMER CONTACTS

FIGURE 3 29

calculating the location of the center of mass of any tube and

its contained suspension. The equation used for calculating the

radius of center of gravity of the tube and its contained

suspension ) is derived and is shown in Appendix A. (rt The pendulum period was measured by giving a very small

amplitude. With the timer used, it was possible to measure

accurately the half time period of the pendulum. For the tube in

each position (with or without block), the pendulum was carefully

released with the same amplitude from the left and right side.

Half time period was measured ten times from the left and then

ten times from the right. Averages for each of these values were

added to get the total time period. Average deviations observed

in the total time period measured this way were less than 0.1%.

Settling studies were made in a 1" diameter, 18" long

standard wall glass tube. The tube end was sealed by carefully

pulling the point (glass blowing operation). Freshly prepared

slurry was placed in such tube (with slurry height of about 16")

and then allowed to equilibrate with the room temperature for one

hour. A level mark was then made on the tube and initial time

period measurements were carried out. For the stability tests at

higher temperature the tubes were placed in an oven

maintained at 60°C. Period measurements for such tubes were made

at room temperature. In order to account for the mixture's

volume change that has been occured at higher temperature, the

tube was taken out from the oven and allowed to equilibrate with 30

the room temperature for about an hour before the time of period measurements. By doing so the original liquid level mark was

exactly attained.

For the repeatability of period measurements, the

positioning of tube inside the carriage was found to be very

important. To set the tube with the same position as used

before, the following precautions were made.

After fixing the tube inside the carriage the mark was made

at the tube base to identify its vertical position inside the

carriage. This mark was then used as a reference point for that

tube. Also, initially the tube's angular position inside the

carriage was noted and this position was then repeated at the

time of its period measurement.

The tube was supported inside the carriage with the help of

set screws (Figure 3). One complete rotation of each screw moved

it about 1 mm distance in or out and with the help of markings

made on each screw head it was possible to precisely know its

amount of rotation. While setting the tube care was taken to see

that these screws just touched the tube, thereby minimizing the

tension in the screw and possibility of lifting the tube inside

the carriage. The positions used for each of these screws were

noted (initially) for the tube used and were then repeated at the

time of period measurement.

Barkley et.al. (8) suggests that for the best accuracy, the

carriage should be as light as possible and axis of support 31

should be only a short distance above the center of gravity of the pendulum. In the present study, the weight of the carriage was about 70 grams, while that of the tube and its contained suspension was about 300 grams (weight of the empty glass tube was about 108 grams). The best position for the pendulum's axis of support was detemined experimentally, using the method described below (42).

Figure 3 shows that the carriage was supported with the help of pointed stainless steel bolts (pivot points). One complete rotation of each bolt moved the center of gravity of the pendulum up or down by a fixed amount, depending upon the thread to thread distance ot that bolt. Markings were made on the head of each bolt, for its one complete rotation.

The tube containing a stable coal-oil slurry was set inside the carriage (with the block inserted at the bottom). Initially, the center of gravity of the pendulum was moved up by the maximum possible distance. Thread position at this point was noted and was designated as thread number zero. The pendulum period was then measured. After this, each of the pivot point screws was

rotated exactly by one complete rotation, thereby, increasing the distance between the axis of support and e.G. by a fixed amount.

This position was designated as thread number 1. The pendulum period was then measured at this position. The above procedure was then repeated by increasing the thread number by increments of one. Period measurements at each thread position were carried

out. 32

From the data of time period versus thread number a

correlation between the ratio of 'change in time period/change in

error' and the thread number was developed. Such a correlation

can be used to determine the optimum position for the pendulum's

axis of support. Correlations and discussions are presented in

the next chapter.

2. Coal Concentration With Height:

A coal-oil mixture columns were constructed using one inch

diameter chlorinated polyvinyl chloride (cpvc) ball valves

attached 1n series. Valves were interconnected by means of a

threaded nipple so that it could be assembled or separated

easily. Each column consisted of three such ball valves placed

at 6" center to center distance apart and a removable pvc cap

attached at the bottom.

Figure 4 shows a schematic diagram of the column used. The

length of the coal-oil suspension used in such a column was about

16 1/2" and the locations of the sample points were at top, 6"

from top, 12" from top and at the bottom (about 16" from top).

Variations in coal concentration along the column length (height)

was studied by closing the valve, thereby capturing the material

at a desired location. The captured material was then analyzed

for the coal content by the gravimetric method.

A freshly prepared coal-oil mixture was placed in three sets

of such ball valves (set A, Band C, i.e., three columns) 8S well

as in a glass settling tube. The idea was to study the variation 33

q 1 '.D.-B ALL V AL VE // -:

1~ T I.D.N IPPLE

SKETCH OF COAL-OIL MIXTURE COLUMN

FIGURE 4 34

in coal concentration versus height and the drop in C.G. (or change in center of mass) for a given length of time. Time period measurements for the settling tube were carried out at various days. When the period measurements indicated a drop in e.G. of about 1 mm the valves of set A were closed.

Accumulated studies at Adelphi Research Center indicated that any slurry whose center of mass has not shifted more than 1 mm , does not cause a problem in pumping and combustion of such mixtures (14). Also, Barkley, e t s a L, (8) reported the maximum drop in C.G. of about 5 mm for coal-oil mixtures. For these reasons, valves of set A were closed when a drop in e.G. of about

I mm was observed to see how much variation in coal concentration occurred wi th height. Similarly, valves of set Band e were closed when such significant drops in C. G. were again observed during the length of time for the settling tube.

After closing the valves and thereby capturing the material at various locations, the valves were separated from one another. The closed valves were then cleaned from the top and bottom, the valves were opened and the sample was flushed into the beaker. The sample collected from each valve represented an entire one inch section of the coal-oil mixture. The amount collected from each valve was about 15 grams while that from the cap (at the column bottom) was about 20 grams.

Representative I 1/2 to 2 grams of each collected sample were used for the weight percent solid determination by the KVS 35

procedure (see Appendix B for the procedure).

The resultant dry coal particles were then used for the

microscopic examination. Dry coal particles were spreaded evenly

on a microscopic slide so that they formed a very thin layer of

particles. A particle size photograph was then taken using the

Unitrone Series N type microscope. Particle size photographs

were taken for most of the samples of the coal-oil mixture

columns.

3. Tuned Circuit Detector:

Attempts were made to find the rate of drop of a small metal

sphere, under the action of gravity, in coal-oil mixtures. It

was expected that the rate at which the sphere drops through a

coal-oil mixture would vary with height as the coal concentration

or the viscosity variation occurs. This idea was first suggested

by Dr. James Tong (43).

Since No. 6 oil used was very dark in color, the metal

sphere was detected by a tuned circuit detector, which is shown

in Figure 5. The apparatus consisted of a series of coils placed

at one inch center to center distance apart on a clear plastic

tube (acrylic tube having I" I.D. and 1 1/2" O.D.). The glass

tube used for the stability study can be easily slipped in or out

of the plastic tube.

Sixteen coils were used, with each set of four coils driven

by a separate crystal oscillator. The circuit was designed by

A. Swearingen (44) and is shown in Figure 6. When the metal 36

A METAL DETECTOR

USED FOR STABILITY STUDY

FIGURE 5 37 OSCILLATOR DIVIDE CIRCUIT

J.38/1t12-

v'V"------.... r ~J.. I1t1

... \J 10 I( ~ slis Q~ t::o,ls BUFFER J1'" :I.l..n. 1 .... /'11 ~r"U~ ,r- , ~~~'_~---..;~ I~ !/~t T"~~ -v : L._..! }- AMPLIFIER ~~D FILTER

HIGH GAIN .~tPLIFIER AND FILTER

tc: I 'f 0"

CIRCUIT FOR A METAL DETECTOR

FIGURE 8 38

object passed through the coil the inductance in the coil changed

and this change was recorded as the voltage vs . time curve by

means of an XY plotter. The time required for a sphere to travel

exactly 1" distance through the solution was then calculated by

measuring peak to peak distance on a voltage VB. time curve.

Experiments were carried out by dropping small metal spheres

about 1/8" diameter through various solutions. Solutions tried

were glycerine, Brookfield Viscosity Standard (Viscosity 116

poise at 24°C), No. 6 fuel oil and the suspensions of different

percentage coal-in-oil mixtures.

Viscosity and Density Measurements of Coal-Oil Mixtures

Viscosity measurements of coal-oil mixtures were carried out by using a Brookfield RVT model viscometer. A preliminary study made in this laboratory on No.8 coal/No. 6 fuel oil mixture indicated its non-Newtonian behavior. Usually t doubling the spindle speed (shear rate) did not double the dial reading and the prolonged application of shear showed a decrease in the value of mixture's viscosity.

To study the possible non-Newtonian and thixotropic behavior of a coal-oil mixture t the dial readings were noted first by increasing the spindle speed from 2.5 to 5, 10 and 20 RPM and then by decreasing the speed in the reverse order. Usually the dial readings were noted for many spindle rotations till a constant viscosity value was observed. The flow curves for coal-oil mixtures were then obtained by plotting the dial reading as abscissa against the spindle speed 39

(RPM) as ordinate.

H. Green (45) suggest that on the flow curve if there is a

separation between the up and downcurve t the material is thixotropic.

The amount of thixotropy can be represented by the area between the up and down curve on the graph. The larger the area between the up and down curves the more thixotropic Is the material. Similarly, if there is no separation between the up and down curves then the material is not thixotropic (45).

Viscosities of No. 6 fuel 011 and the low percentage coal-in-oil suspensions (15 to 20 percent coal by weight) were measured by spindle No. 1 in a 600 mI. Pyrex beaker. For the higher percentage coal-In-oil suspensions spindles No.4, 5 or 6 were used depending upon the viscosity of the material. Viscosity measurements for such mixtures were carried out in a 100 ml , Pyrex beaker with a slurry height of about 2 inches. Viscosity measurements for the coal-oil mixtures were made at low spindle speed to minimize the error due to spindle cavitation.

For the Brookfield Viscometer used t the shear rate doubles in value if the spindle speed is doubled, however , the exact value of shear rate can not be determined. Private communications made with the Brookfield Engineer indicated that for RVT model spindles, the lowest shear rate of about 0.1 sec-1 would be induced by No. 7 spindle at a speed of 0.5 RPM while the highest sheer rate would be under 100 sec-1 for No. 1 spindle at a speed of 100 RPM. Due to the geometric similarities among the RVT model spindle Nos. 4, 5 and 40

6 it was expected that the sheer rate induced by such spindles at low speeds would be about the same.

Since the viscosity measurements for the higher percentage coal-in-oil suspensions were made in a non-conventional way, attempts were made to calibrate the dial readings. To do this, a standard solution (Brookfield Viscosity Standard) having a viscosity of 116 poise at 24°C was placed in a 600 mI. beaker as well as in a 100 mI. beaker. Dial readings were carefully noted using No. 6 and No. 7 spindles at different speeds, first in a 600 mI. beaker with the guard attached at the viscometer in the conventional way, and then in a 100 mI. beaker without the guard attached. Dial readings so obtained were then compared and were found to be about the same in both size beakers.

The viscosities of Ohio No. 8 coal in No.6 oil (COM) and of solid solvent refined coal in No. 6 oil (SOM) were measured at varying weight percent coal-in-oil, particle size of the coal and

temperatures. Viscosity of any sample was measured at the start (for freshly prepared mixtures) and then after aging, usually for a period of about 8 days. During the entire period of viscosity measurement

for any sample, the arrangement of the spindle and the beaker containing the suspension were not disturbed physically, except for

the small disturbances caused by the spindle rotations at the time of

viscosity measurements. This was done to avoid any disruption of

settling of coal particles occurring in a coal oil mixture during the

period of viscosity measurements. 41

The particle density of coal was determined pycnometrically. The

known amount of powdered coal (about 90% passing through 150 micrometer screen) was taken in a 250 ml , volumetric flask. The

flask was then filled with methanol up to the mark and the

temperature was noted. Any air present between particles was then

removed by applying a vacuum (water aspirator). The flask was again

made up to the mark with methanol and then weighed accurately.

Knowing the density of methanol used, it was possible to calculate

the volume occupied by the coal particles. Knowing the weight and

volume, the average density of coal particles was then found. In one

experiment the No. 6 fuel oil was used instead of methanol for the

density determination of No. 8 coal, using the above procedure.

Density of No. 6 fuel oil was determined at room temperature

(25°C) and at 60°C by filling a 500 ml . flask up to the mark and weighing it accurately. Density determinations at 60°C were made by

using an oven constantly maintained at 60°C.

Density determinations of coal-oil mixtures were carried out at

room temperature and at 60°C by using a 25 mI. Hubbard pycnometer.

Both the mixtures of No. 8 coal/No. 6 fuel oil and Solvent Refined

coal/No. 6 fuel oil were used with varying weight percent coal in

oil. Volume of any pycnometer or volumetric flask used for density

purpose was determined accurately by filling it with distilled water

(at known temperature) and then weighing it accurately. 42

Coal-Oil Mixture Sample Preparation

Ohio No. a coal was obtained from Belmont County. The analysis of this coal is shown in Appendix C. The solid solvent refined coal was supplied from the Pittsburgh and Midway Coal Mining Company. The

Low ash coal was prepared in this laboratory by the coal dissolution process.

The coal used throughout the laboratory tests was ground in a ball mill and various sizes were separated carefully by using U.S. standard sieves in a Ro-Tap sieve shaker. Powdered coal was then dried in an air drying cabinet maintained at 50°C for 24 hours, before mixing it with oil for testing. No. 6 fuel oil was supplied by the Ashland Oil

Company.

Laboratory samples were mixed by vigorous stirring under about 10 mm vacuum to remove the air carried into the oil by the coal particles. Various coal-oil mixtures were prepared, using the following procedures:

1. A known quantity of No. 6 oil was heated up to 70-80°C in a

600 mI. beaker.

2. A known quantity of powdered coal was then dispersed slowly

into the oil, while hand mixing.

3. The mixture was again heated up to 7o-aO°C, while hand mixing

and then transferred to a Osterizer dual range blender.

4. The mixture was then blended under about 10 mm vacuum using

a Duo Seal vacuum pump. The blender was operated for every

10 seconds in a minute for the period of about 15 minutes at 43

a speed of about 2900 RPM.

5. Vacuum only was then applied for 30 minutes to remove the

entrapped air from the warm mixture.

After releasing the vacuum (took about 5-10 minutes), the prepared slurry was then used for the stability study or viscosity and density measurements.

Preparation of Low-ash Coal

1. Extraction with phenanthrene:

Dissolution of two types of Ohio coals i.e. No. 8 and No. 4A

coal in phenanthrene (technical grade) at atmospheric pressure

was carried out. Procedures used here were similar to those used

by the Bituminous Coal Research, Inc. (37) in 1959.

Powdered coal and solid phenanthrene were charged to a three

necked reaction flask, with arrangements for the air con- denser,

stirrer and nitrogen inlet as shown in Figure 7. The flask was

then heated electrically up to the boiling point of phenanthrene

(about 340°C). During the run nitrogen was passed at a small

flow rate to avoid the possible reaction of coal particles with

air. The stirrer was then used at slow speed (about 60 RPM) to

avoid the sticking of the coal particles to the hot surface.

After certain reaction times (amount of time after the boiling

point of phenanthrene was reached) the coal-solvent slurry was

slowly transferred to a Whatman 41 filter paper placed on a

heated (100°C) Buchner funnel. Filtration resulted in the AIR CONDENSER 44

STIRRER THERMOCOUPLE

LID ~GASKET ,/ .CLAMP

I II REACTION KETTLE- II'I 'I

" :I II II HEATING MANTLE ,II II

I," II 'I ,I 'I I, : I ,I ~ .JL__-'P , "

DISSOLVER FOR PREPARATION OF LOW-ASH COAL

FIGURE 7 45

separation of phenanthrene solubles (containing low-ash coal) and

phenanthrene insolubles (containing mineral constituents of coal).

Procedures used for the separation of phenanthrene from both

of these fractions were the same as those used by Bituminous Coal

Research, Inc. (37) except that instead of carbon tetrachloride­

gasoline mixture, a practical grade toluene was used. Extraction

studies were made by using two types of Ohio coals while varying

the coal to solvent ratio and the reaction time.

2. Extraction in Autoclave:

Extraction studies were also made in a one liter stainless

steel autoclave, rated 5000 psi at 650°F (Drawing No. 40-1446,

Autoclave Engineers, Inc. Erie, PA). After consulting with

Southern Services Inc. (46) their procedure for extraction was

used in the autoclave to produce a Low-ash coal. The procedure

that was used is as follows:

Ground coal (Ohio No. 4A, 80% passing through a 74

micrometer screen) and a mixture of solvents were charged into

the autoclave. The composition of a mixture of solvents used was

three parts by weight of l-methyl-naphthalene and one part by

weight of t e t raHn, A solvent to coal ratio of 4:1 was used.

After charging the materials, the autoclave was flushed wi th

nitrogen to remove the air. Heating was then started. The

slurry was heated up to about 750°F and was maintained at this

temperature for a specified

time interval (designated as the reaction time) by controlling the

heat input to the autoclave. 46

During the entire run the stirrer was used at about 600 RPM and the temperature of the mixture was measured periodically by means of a chromel-alumel thermocouple. After a certain reaction time the heating was stopped and the mixture was transferred to the boiling cresol, by carefully opening the sample valve of the autoclave. A cresol to slurry ratio of about 3 to 4 was used.

The cresol was used primarily to facilitate the filtration of coal- solvent slurry by acting as a dfLuant , The resultant mixture was boiled and then poured on a Whatman 41 filter paper placed on a heated Buchner funnel. A small vacuum was applied

(using a water aspirator) to increase the filtration rate.

Filtration resulted in the separation of solvent solubles containing cresol plus low ash material and solvent insolubles primarily containing mineral constituents of the coal plus a small amount of cresol. The solvents and cresol were then separated from the low ash material first by atmospheric distillation and then by applying a vacuum of about 50 mm using a Duo Seal vacuum pump.

The resultant low ash coal was used for ash and sulfur analyses by ASTM methods. The low ash material was ground in a mortar and pestle to a fine size and then carefully screened

(size range about 50% passing through 75 micrometer screen). The powdered material was then mixed with No. 6 fuel oil for the evaluation of settling stability. APPARATUS

PHYSICAL PENDULUM Wooden carriage with the arrangements for suspending the glass tube. Designed by the author. Made at physics shop, Ohio University, Athens, Ohio. Used for measuring center of mass of tube and its contained suspension.

SETTLING TUBES About 1" I.D. and 18" in length. Tubes made from standard wall glsss tube. 1" I.D. and 48" in length. Corning Glass Co.; by a glass blowing operation. Tubes used for the stability study.

PHOTOCELL Used for the pendulum period measurements.

ELECTRONIC TIMER Made at physics lab, Ohio University, used for the pendulum period measurements.

BALL VALVES CPVC ball valves, about I" I.D., Cole-Parmer Instrument Company; 11105 342 508, Type 342, threaded valves used for the coal-oil mixture column construction.

NIPPLES CPVC nipples, about I" I.D. used for interconnecting ball valves.

CAPS CPVC, 1" I.D. threaded caps, used for closing the coal-oil mixture column at bottom.

A METAL DETECTOR Apparatus made from acrylic tube about 1" I.D. and 1 1/2" O.D., acting as a metal detector. Designed and made at Engineering Building, Ohio University, Athens, Ohio.

XY PLOTTER Crystal controlled, single pen chart recorder. Schlumberger Company. Model number SR-205. Used with Tuned Circuit Detector to detect metal sphere. Output as the voltage vs. time curves.

VISCOMETER Brookfield RVT model viscometer, Brookfield Company. Used for viscosity measurements of the coal-oil mixtures.

STOP WATCH Clebar 0 to 30 seconds, 0.1 second divisions, used to measure time. 48

PYCNOMETER 25 mI. Hubbard type pycnometer, Corning Glass company; 1101-716 Corning #1620, used to measure density of coal-oil mixtures.

VOLUMETRIC FLASKS 250 and 500 mI. volumetric flasks, Corning Glass Company; 1I10-21lE and IIlD-2llF, used to measure particle density of coal and density of No. 6 oil.

BEAKERS 100 and 600 mI. pyrex beakers, Corning Glass Company; 1I02-540H (Corning 1000) and #02-555-25D (Corning 1003) used to measure the viscosity of coal-oil mixture samples.

GRINDING EQUIPMENTS Norton Jar Mill, n CK-79l60, used for grinding coal. Jar made of Roulox porcelain, 5 liter capacity, Norton Jar Company; II 113-2, with Byrundum as a grinding media, cylindrical shape, Fisher Scientific company, # 8-4l2-l5B, used for grinding coal.

SIEVES U.s. Standard Sieve series, Dual Manufacturing Company; 50, 100, 200 and 325 mesh sizes used to sieve coal particles.

SIEVE SHAKER Ro-Tap, model B, Testing Sieve Shaker, # 1882, Tyler Industrial Products.

BLENDER Osterizer Model, Dual range blender, Osterizer Company, with 5 cups stainless steel container, used for the coal-oil mixture sample preparation.

ELECTRIC HEATER Thermcraft electric heating units, used to heat coal-oil mixture placed in 600 mI. beakers.

THERMOMETERS General Laboratory Mercury Thermometer, Fisher Scientific Company, used to measure the coal-oil mixture temperature.

POWERS TAT Supe rior Edison Co , , powerstats, type 116, output 0-140 volts, used to control heat input.

VACUUM PUMP Duo Seal vacuum pump, W.M. Welch Manufacturing Company; with 0-30 inches mercury vacuum gauge, used for coal-oil mixture preparations as well as for low-ash coal preparation. 49

RESIN FLASK 4000 ml , pyrex resin flask, reaction kettle, O.D. 14 em, length 23 em, Fisher Scientific Company; #11-847E, used for the extraction with phenanthrene.

AIR CONDENSER Fisher Scientific company; #07-72l-5B, 300 mm length, used for solvent extraction unit.

STIRRER Metal stirrer about 20" long, made at Ohio University with turbine type blade attached. Driven by 1/4 HP variable speed motor. Used to stir the coal-solvent slurry.

BUCHNER FUNNEL Porcelain 269 mm diameter filtering funnel, Fisher Scientific Company; IIl0-365J used for filtering coal-solvent slurry.

FILTER PAPER Whatman 41 Filter paper, 24" size, dia. Fisher Scientific Company used for filtration of coal-solvent slurry.

CLAMPS Fisher clamps ll-847-30B. Used to join kettle top to bottom.

DISPERSION TUBE Fitted disc type coarse, pyrex #11-137-5B, Fisher Scientific Company. Used for filtering coal-solvent slurry.

Fitted cylinder type coarse, pyrex flll-138B (Corning #39533) Fisher Scientific Company.

AUTOCLAVE One liter bolted onto clave, Drawing 40-1446, Autoclave Engineers Inc., Erie, PA.

THERMOCOUPLE Cromel-alumel thermocouple wire; used to measure temperature of coal-solvent slurry.

EXPERIMENTAL GAS Nitrogen-Burdett Oxygen Company; N2 used for solvent extraction study.

PHENANTHRENE Tech Grade phenanthrene, px 455, Matheson Coleman & Bell, Norwood, Ohio. Used for Solvent Extraction.

SRC I Solid Solvent Refined Coal supplied by The Pittsburgh and Midway Coal Mining Company. Sample 111490. RESULTS AND DISCUSSION

Stability Studies

1. Particle size distribution:

Dry sieve analysis for the different size coal particles used

for the mixture preparation are shown in Table 2 for Ohio No. 8

coal and in Table 3 for the solid Solvent Refined Coal (SRC).

Resultant data were plotted on the log probability paper as the

particle size in micrometers vs. cumulative weight percent solids

retained.

Figure 8 shows the size distribution for Ohio No. 8 coal on

the log probability paper for various size ranges, i.e. size

range AI, A, Band C. For each of these curves, the particle

diameter (d) at cumulative weight percent of fifty, d which SO' represents the average particle diameter and the ratio of

d16/dSO which represents about two-third of the distribution

for any sample was found (47). Values for d50 and the ratio of

d16/dSO are also shown on Figure 8 for each of these curves.

The ratio d16/dSO varied from 1.28 to 1.35 for the different size samples of No. 8 coal.

Figure 8 show that curves AI, A, Band C are almost parallel

for 2/3rd of the distribution. These findings indicate that the 51

TABLE 2

DRY SIEVE ANALYSIS FOR OHIO NO. 8 COAL

CUMULATIVE WEIGHT % SOLIDS RETAINED FOR DIFFERENT SIZES SIEVE SIZE SIZE Al SIZE A SIZE B SIZE C IN MESH -325 MESH -200+325 MESH -100+200 MESH -50+100 MESH

50 (300)* 0.1 0.3 0.3 0.4

100 (150) 0.6 0.8 1.1 38.0

200 (75) 2.6 2.3 57.3 86.6

325 (44) 10.8 38.6 82.4 93.4

*indicates the size in micrometers. 52

TABLE 3

DRY SIEVE ANALYSIS FOR SOLVENT REFINED COAL

SIEVE SIZE CUMULATIVE WEIGHT % SOLIDS RETAINED FOR DIFFERENT SIZES IN MESH SIZE D SIZE E SIZE F -200+325 MESH -100+200 MESH -50+100 MESH

50 (300)* 0.15 0.5 3

100 (150) 0.4 1.3 28.5

200 (75) 3.1 23.5 60.5

325 (44) 90.1 54.3 90.5

*indicates the size in micrometers. lOQ .. ' .. 'H"IC .. "O Il.". .• 'c.., ..... HA t .... oN',"~rl• .. PlH \ NOlt2e .... n' o." •• ..(tI51'f. (')f11 • • ()f)" (u .. ,...... y 1"'( f1tnlltwqlll1 ...... ( HII •• 'l.

(~:)

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1 0 a.cn ' ! ~_~~I\::!!'" ! I" '''11 I r I I!! I ULUllllI I f I Ill' ---- ~1 02 0.& 1 MJ IiU 10 80 to 95 98 99 995 998 99.9

CUMULATIVE WEIGHT PERCENT RETAINED

FIGURE 8 SIZE DISTRIBUTION FOR NO.8 COAL til (M 54

size distribution for the various size No. 8 coal samples used

for the stability study were almost similar.

For the solid SRC particles, Figure 9 shows that the size

distribution curves D, E, and F are not parallel and the ratio of

d varied from 1.18 to 1.95. These findings suggest 16/d50 that the size distributions for the various sizes of Solvent

Refined Coal used for the stability study were disimilar. This

could be due to the agglomeration of small size SRC particles.

2. Pendulum Studies:

The stability studies of 50 percent by weight suspensions of

different types of coals in No. 6 fuel oil were made in which the

particle size of coal and the temperature were varied. The com­

positions of the coal-oil mixtures used for stability studies are

listed as Tests 1 through 8 in Table 4.

The results for the stability tests are shown in Table 5 for

No. 8 coal-oil mixtures and in Table 6 for the SRC-oil and Low-ash

coal-oil mixtures. Data are reported as the day of test vs. drop

in center of mass of the tube and its contained suspension. Zero

day indicates the day of sample preparation and at zero day the

drop in center of mass of the sample was taken as zero in value

(basis of calculations).

The drop in center of gravity (c s g , ) for the tube and its

contained suspension was calculated from the history of time

period variations using the pendulum formula derived in Appendix

A. The data for the time period variations for the above

mentioned Tests 1 through 8 are given in Appendix D. NO. 3128 LOG""'TH"'IC ~"O.".'LITv , DItI'GNfO .... H"'lN WH' .... Lf • '-UlLl" COOlll .001( co .....,,"', INC HO"W000 lIol"II"CHUIITTI .~ '.l ..'IO"'u .... ~~ ":..~<

99.999.' ".1" 9' 95 90 80 70 60 60 40 30 20 10 1 0.5 0.2 0.1 0.05

1000 99r9~"D1InillZm.m~mRTImemr]!IIIIIWfllB1!t~~!i~~~I~ ~_~ tI1P-'~-~-

···j~t-1~jtrf·t:ttit"i;11l~ 1----1 t'fiP:t; I If I·ir~·rfItI t ~~.:.t I ~-=--:t_.L1l,:i ~~-';rL111~:=1~~~1~fll.~IIL.llll!l;:~~+-H-H+'+i++": W .. " !1~llll'1.':rrrJt'" ~ i _~t01:~P.t-*t==f=l:#m#t=m1=-::=:E=tFt=::t=t=:ttrnmNJI H ! i I A'1 1u! iJ :1i t: I I!iII

N ~~I l' ! I IiNJJ. I t l'~·Urtlnlt1ll-l--t1~mti1ti7~-- 1 ___., , lt1 11 ! t ~~-nH il1 ddTl ftt--~~._ en- t=.--~ ITl Ufl1l--] H .. aJtllf~:f:[ .~:

~·t==t=i:.~ -.. •..-. ~J:::t-t=.-.t:-: t=-.+=t=-·1 f--

t--+-+-+f+HH---+-I-----t--4I+H+I~·~I.H-=~-=t~=t-=--E

-~_._-6 -~- ...... ,1.1"'1 f"..J.lllllljt~l-i--j~,*'HIHf-I+~

§Dllff +-+4·~I-H·; .1111 ~l=~__ -e= '"

--+-. t-~-+--, tt= -t--f- ...-+-+++t+++·~ t t-H t H tt++tH H-t+t++++t+-H-+fH+H-H-+H+++++-~-+--H++J t I HtI--+-+-+-I-H-l-H J-H f +-1---+---4--1---· -I-f -+-+_.- 1 0 0....• ...... - - - - 10 20 30 40 51) 80 70 80 90 95 98 99 99.5 99.8 99.9 99.99

CUMULATIVE WEIGHT PERCENT RETAINED

SIZE DISTRIBUTION FOR SOLVENT REFINED COAL Ul FIGURE 9 <.n 56

TABLE 4

COAL-OIL MIXTURE COMPOSITIONS USED FOR STABILITY STUDIES

TEST SETTLING TUBE NUMBER DESIGNATION DESCRIPTION

I PI 50 percent by weight Ohio No. 8 coal in No. 6 fuel oil, coal particle size -100+200 mesh (size range B*), stability test at 25°C.

2 P2 50 percent by weight Ohio No. 8 coal in No. 6 fuel oil, coal particle size -100+200 mesh (size range B*), stability test at 60°C.

3 P3 50 percent by weight Ohio No. 8 coal in No. 6 fuel oil, coal particle size -200+325 mesh (size range A*), stability test at 60°C.

4 P8 50 percent by weight Ohio No. 8 coal in No. 6 fuel oil, coal particle size -325 mesh (size range A1*), stability test at 60°C.

5 P4 50 percent by weight solid SRC in No. 6 fuel oil, coal particle size -50+100 mesh (size range F*), stability test at 25°C.

6 P6 50 percent by weight solid SRC in No. 6 fuel oil, coal particle size -200+325 mesh (size range n*), stability test at 60°C.

_7 P7 50 pe rcent by weight Low-ash coal in No. 6 fuel oil, coal particle size -200+325 mesh, test at 60°C.

8 P8 50 percent by weight solid SRC in No. 6 fuel oil, coal particle size -100+200 mesh, (size range E*), stability test at 25°C.

*For size range details see Figure 8 for Ohio No. 8 coal and Figure 9 for solid SRC. 57

TABLE 5

SETTLING DATA FOR COAL-OIL MIXTURES

50% BY WEIGHT SUSPENSION OF OHIO NO. 8 COAL IN NO. 6 FUEL OIL

Test Number 1 2 3 4 Settling Tube Number PI P2 P3 P8 Size Range***, B B A Al Size, passing mesh -100 -100 -200 -325 Temperature, °c 25 60 60 60

Day of Test Drop in center of gravity* in millimeters.

0** 0.00 0.00 0.00 0.00 1/4 0.38 1/2 0.64 0.30 1 0.75 1.79 2 2.67 0.56 4 0.65 0.51 (for 3 days) 6 2.08 0.60 8 2.30 3.77 1.01 0.67 (for 7 days) 12 2.97 4.19 1.26 1.07 (for 14 days) 16 4.08 1.54 1.25 24 3.50 1.74 2.00 (for 20 days) 32 4.12 4.33 1.92 48 4.77

*Drop in center of gravity of a sample in I" x 18" tube, with a slurry length of about 16". Uncertainty in e.G. + 0.1 millimeter.

**Zero day indicates the day of sample preparation.

***For size range details see Table 2 and Figure 8. 58

TABLE 6

SETTLING DATA FOR COAL-OIL MIXTURES

50% BY WEIGHT COAL IN NO. 6 FUEL OIL.

Test Number 5 6 7 8 Coal Type SRC I SRC I Low-ash SRC I Settling Tube Number P4 P6 P7 P8 Size Range *** F D E Size, passing mesh -50 -200 -200 -100 Temperature, °c 25 60 60 25

Day of Test Drop in center of gravity* in millimeters

0** 0.00 0.00 0.00 0.00 1 -0.23 -0.24 2 -0.35 -0.82 4 0.44 -0.57 0.27 9 0.75 0.43 0.34 (for 8 days) 12 -0.14 0.25 16 0.85 0.28 0.84 24 0.39 1.22 0.90 0.92 32 0.82 1.77 1.42 0.83 40 0.93 2.90 60 1.04

*Drop in center of gravity of a sample in 1" x 18" tube, with a slurry length of about 16". Uncertainty in C.G., + 0.1 millimeter. Negative values indicate a rise in e.G.

**Zero day indicates the day of mixture preparation.

***For size range details see Table 3 and Figure 9. 59

The results for the stability tests were plotted as the drop in center of gravity in millimeter (mm) on the ordinate vs. days on the abscissa and are shown in Figure 10. Smooth curves were drawn through the experimental points to compensate for the spread caused by experimental error.

Curves A, B, and C in Figure 10 show the effect of particle size on stabil!ty of 50 percent by weight suspensions of No. 8 coal in No. 6 fuel oil at 60°C. In the first 10 days the suspen­ sion containing -325 mesh size particles showed a C.G. drop of about 1.25 mm, -200 mesh size particles showed about 1.50 mm and

-100 mesh size particles showed a drop of about 3.90 Mm. These findings indicated that the initial settling rate for the coarse size No. 8 coal particles in No. 6 oil was much higher than for the fine size particles. Since the drop in e.G. directly reflects settling stability of the mixture, test results showed that the stability of No. 8 coal/No. 6 oil mixtures increase with increase in coal fineness. Curves A and B in Figure 10 also show that the difference in e.G. drop values were relatively small between the suspension containing -200 mesh size particles and -325 mesh size particles. These findings indicate that the stability of No. 8 coal/No. 6 oil mixture at 60°C does not improve in proportion to a particle fineness beyond -200 mesh size.

The curves C and D in Figure 10 show the effect of temperature on e.G. drop pattern of No. 8 coal/No. 6 oil mixtures. The settling stability for the same sized No. 8 coal

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particles in oil was decreased with increasing temperature as evidenced by the increased e.G., drop at 60°C compared to the drop at 25°e. Also, the initial rate of C.G. drop was higher at 60 0e than at 25°e. These findings indicated that the settling rate of

No. 8 coal in No. 6 oil will be accelerated if the temperature is increased. The increased settling of particles at higher temperatures may be due to the rapid decrease in the coal-oil mixture's viscosity with temperature.

The curves E, F and G in Figure 10 show the relationship between e.G. drop and time for solid Solvent Refined Coal/No. 6 fuel oil (SOM) mixtures. The drop in C.G. for SOM was much less than for COM (No. 8 coal/No. 6 fuel oil mixture) of equivalent composition as evidenced by the position of these two sets of curves in Figure 10. For example, compare curves D and F in

Figure 10. For the first 10 days of settling, curve F (SOM, -100 mesh, at 25°C) shows a e.G. drop of 0.5 mm while curve D (COM,

-100 mesh, at 25°C) shows a drop of about 2.6 mm, which indicates that the settling of No. 8 coal particles in No. 6 oil was taking place at a much faster rate than for solid SRC particles of the same size. These findings indicated that if all other variables

(such as particle size, temperature) are kept the same, SOM will be more stable than COM of equivalent composition.

Since size distribution for the different size SRC particles was found to be dissimilar (see discussion on particle size dis­ tribution on p. 54 and Figure 9 on p. 55), no definite conclusion 62

can be reached for the relationship of particle size and stability of this mixture. The primary problem in separating the fine size

SRC particles from the coarse ones by the dry sieving technique was the agglomeration of the small size SRC particles. Here the wet sieving technique may be more helpful.

However, the marked difference between the C.G. drop pattern of SOM and COM reveals that it is the nature of the Solvent

Refined Coal rather than its size or any other factor that makes

SOM more stable than COM of identical compositions. Solvent

Refined Coals tend to homogenize with the No. 6 oil on mixing and produce a higher viscosity mixture. Additionally, the viscosity of SOM was found to be much higher than for COM of equivalent composition (as will be discussed latter) and this could be the reason for it's greater stability.

The e.G. drop pattern for Low-ash coal/No. 6 fuel oil mixture is shown by curve H on Figure 10. The curve H lies above that of SOM (curve E) and COM (curve B) of identical composition. All three curves were obtained at 60°C. These findings indicated that Low-ash coaL'No. 6 fuel oil mixture was more stable than COM or SOM of equivalent composition. The

Low-ash coal was prepared in this laboratory from Ohio No. 4A coal by the coal liquefaction process.

A small rise in center of gravity was observed, initially, for the first few days for the suspension of Low-ash coal-oil and the one sample of SOMe This rise in e.G. is shown as the negative 63

of C.G. drop for the curve G and H in Figure 10. Other authors

(14) indicated that the rise in e.G. represents an agglomeration

or flocculation of coal particles taking place in the oil. How-

ever, the pendulum apparatus gives only an overall picture of the

settling process and can not reveal the details of such phenomena.

3. Error Analysis for the Pendulum:

To obtain a measure of reproducibility of the pendulum

system, a standard tube (P12) and a tube containing No. 6 fuel

oil (P were used. The data for the period variation and oi l) the calculated value of are shown in Table 7 for the standard r t tube (Test No.9) and in Table 8 for the tube containing No. 6

oil (Test No. 10).

Results of these tests show that repeatedly fixing the tube

inside the carriage resulted in a period variation of about 0.6

to 1%, 0.6 percent period variation for the standard tube and 1

percent for a tube containing No. 6 oil. The Student t-test on

the data shows that for the 98% confidence level, the C.G. of any

tube and its contained suspension can be located within 0.006 to

0.01 ems, using the formula given in Appendix A.

The formula used for the C.G. calculations is of the form,

c 2) -T e 1 +

where a, b,c,d and e, all are positive and the time period, T 2 greater than T I• As settling occurs, the values of both 64

TABLE 7

PENDULUM REPRODUCIBILITY DATA

TEST NUMBER 9 - USE OF STANDARD TUBE*

DAY OF TIME PERIOD, T2 TIME PERIOD, T1 VALUE OF rt** DEVIATIONS TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS IN rt (mm)

4/11/80 2253 + 1.83 1686 + 1.3 9.593 0.009

4/12/80 2284 + 2.3 1680 + 1.7 9.650 0.048

4/13/80 2240 + 3.5 1677 + 0.8 9.649 0.047

4/15/80 2246 + 1.6 1679 + 1.0 9.557 0.045

4/16/80 2255 + 2.3 1685 + 1.5 9.532 0.070

4/18/80 2252 + 2.2 1688 + 1.3 9.695 0.093

4/23/80 2244 + 3.5 1679 + 1.3 9.597 0.005

4/25/80 2254 + 2.8 1685 + 2.3 9.541 0.061

* A tube filled with the homogenous solution so that it's weight was about the same as other stability test tubes.

** r t means radius of center of gravity of the tube and its con­ tained suspension, calculated by the formula given in Appendix A.

Note: With these data, the Student t-test for 98% confidence level indicated a deviation of about ± 0.06 millimeter in the value of Ft. 65

TABLE 8

PENDULUM REPRODUCIBILITY DATA

TEST NUMBER 10 - USE OF TUBE CONTAINING ONLY NO. 6 OIL

DAY OF TIME PERIOD, T2 TIME PERIOD, T1 VALUE OF rt** DEVIATIONS TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS IN rt (mm)

3/30/80 2286 + 1.5 1696 + 1.3 9.354 0.036

4/ 7/80 2308 + 1.6 1712 + 1.1 9.332 0.014

4/ 8/80 2290 + 2.7 1696 + 1.4 9.226 0.092

4/16/80 2281 + 2.9 1694 + 1.3 9.423 0.105

4/17/80 2294 + 2.9 1700 + 1.4 9.227 0.091

4/18/80 2289 + 2.4 1698 + 1.6 9.347 0.030

** rt means radius of center of gravity of the tube and its con­ tained suspension, calculated by the formula given in Appendix A.

Note: With these data, the Student t-test for 98% confidence level indicated a deviation of about + 0.1 millimeter in the value of "Ft. 66

T and T decrease, causing decreases in value of both I 2 numerator and denominator (in the above formula) and an increase in the value of - rt Experimentally, the decrease in the value of the denominator was found to be larger than that of the numerator. As an example, for Test No. I (See Appendix D for data) an increase in value of

by 4.12 mm (4.12 drop) was accompanied by a 12.3% r t e.G. decrease in value of T a 7% decrease in value of T and 7% 2, I and 32.5% decreases in values of numerator and denominator respec- tively. With the pendulum arrangement that was used, it can be said that the change in value of depended upon the change in r t value of the difference of the square of the time periods 2 2 (T -T and not just upon the change in T or T 2 I) Z l- As mentioned previously, the best position for the pendulum's axis of support was determined experimentally _ The procedure that was used is mentioned in the previous chapter_ At each thread position (which signifies a fixed distance between pendulum's C. G. and its axis of support) the time period of T Z and the deviation in T2 were noted _ The error analysis data are reported in Table 9 as the thread number versus time period,

T2, and the deviations in time period, 6'.

Relationships of the time period T2 and it's deviation 6 versus thread number are shown graphically in Figures 11 and 12, respectively_ In Figures 11 and 12, smooth curves were drawn to account for the experimental error. Using these curves, the 67

TABLE 9

ERROR ANALYSIS FOR THE PENDULUM

THREAD TIME PERIOD T2 DEVIATION IN T2' 6* NUMBER (MILLISECONDS) (MILLISECONDS)

0 3577 5.6 1 3376 8.1 2 3026 4.6 3 2923 3.0 4 2716 3.6 5 2560 2.8 6 2464 3.0 7 2369 2.4 8 2282 2.5 9 2180 2.6 10 2112 1.6 11 2040 2.0 12 1988 2.0

*Standard deviation with ten measurements of T2. Time period reported here 1s the average for 10 values. 4000 68' "U) Q z 3500 0 0 o w en ..J 3000 ..J- ...,::E

...(\1 .. 2500 c 0 a:: w c, 2000 w :E ... 1500 0 1 2 3 4 5 6 7 8 9 10 1112

THREAD NUMBER c FIGURE 1 1 PENDULUM ERROR ANALYSIS 0 a::- w 6 0."(f) we 5 :E z -0 4 1-0 ZW -0 3 z-'- O..J 2 -I-~- o cc-..., 1 > W 0 Q 0 1 2 3 4 5 6 7 8 9 10 1112 THREAD NUMBER

FIGURE 12 PENDULUM ERROR ANALYSIS 69

corrected or average values for T and were obtained at each 2 6 thread number. Table 10 shows the corrected values of T and~ 2 along with the values for AT, ~T and the ratio A T/ ~ T between each successive thread.

If one considers the time period as the signal and deviation in the time period as the error in signal value, then AT/ ~T represents the ratio of signal/error for the pendulum apparatUs.

Table 10 indicates that when the thread number was increased

(thereby increasing the distance between the pendulum's e.G. and its axis of support) the values of AT and "AT and its ratio were decreased as well as its ratio. The relationship between the thread number and ~T/ ~~T is shown graphically in Figure 13.

Table 10 shows that as one decreases the distance between the

C.G. and axis of support the value of AT and ~T both would increase. At this position the increase in the period value was due to a decreased pendulum's length while the increase in error value could be due to the increase of friction at the pivot points and to air currents associated with pendulum movements as compared to the pendulum restoring torque. Figure 13 indicates that when the thread number was decreased from 10 to 5, the ratio of AT/ 6AT remained almost constant at a value of about 25. As the thread number was reduced further the ratio increased and reached about 35 at a thread number of zero.

Theoretically, if the distance between the e.G. and axis support is zero then the pendulum period will be infinite and 70

:f TABLE 10 ~ It ERROR ANALYSIS FOR THE PENDULUM

THREAD TIME PERIOD DEVIATION AT** 0:*** NUMBER T2* 6* AT AY~T MILLISECONDS MILLISECONDS

0 3580 5.6 265 7.5 35.3 1 3315 5.0 230 6.7 34.3 2 3085 4.5 195 6.0 32.5 3 2890 4.0 180 5.4 33.3 4 2710 3.6 130 4.9 26.5 5 2580 3.3 120 4.4 27.3 6 2460 2.9 100 4.0 25 7 2360 2.7 90 3.6 25 8 2270 2.4 85 3.4 25 9 2185 2.2 75 3.0 25 10 2110 2.1 70 2.8 25 11 2040 1.9 55 2.6 21.1 12 1985 1.8

*Corrected values of T2and ~from the curves of Figures 11 and 12.

**Change in time period between successive threads. (2. 2.)~ ***Deviation between each successive threads calculated as ~2- == ,d'[ +4 •

--J

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YSIS:

NUMBER

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20

30

40

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the ratio ATI ~T will be a very large number. If a settling

study were made at a very large time period then even a very small

e.G. drop or settling of a very few coal particles could be

detected precisely. However, there is an upper limit to the

degree of precision one can get. At such a position, frictional

forces at pivots points and air currents associated with pendulum

movements usually become significant as compared to pendulum

restoring torque. As a result, large deviations in period

measurements occur.

Experimentally, at the position corresponding to about thread

number 1, setting of the tube inside the carriage was found to be

very critical. A small error in the setting of the tube resulted

in a large variation in a time period value. Since the repeat­

ability of the period measurements was very important it was

decided to operate the pendulum at a little less sensitivity.

The position of the carriage was fixed at about thread number 6

and then used for the entire stability study. At thread number 6

the sensitivity of the pendulum was reduced but the accuracy and

repeatability of the .period measurements were increased. At this

position, fixing of the tube inside the carriage was found to be

accurate enough and the period measurements were repeatable

within a small experimental error.

Coal Concentration with Height

As mentioned previously, coal-oil mixture columns were con- 73

structed using cpvc (chlorinated polyvinyl chloride) ball valves to study the variation in coal concentration with height.

The 50/50 by weight mixture of No. 8 coal/No. 6 oil was prepared and placed in a settling tube PI as well as in a three different coal­ oil mixture columns, i.e. valves of sets A, Band C. The idea was to study the possible correlation between the C.G. drop and the variation in coal concentration along the column length for such a mixture.

The study was made at 25°C and coal particle size used was -100+200 mesh size (for size distribution, see curve B on Figure 8, page 53).

When a e.G. drop of 0.75 millimeter was observed for tube PI (in the pendulum apparatus), the valves of set A were closed. Samples collected from each valve AI, A2 and A3 and cap A4 were analyzed for weight percent coal by a gravimetric method (Appendix B). Similarly, when e.G. drops of 2.3 mm and 3.5 mm were observed, the valves of sets Band e were closed respectively and analyzed for the coal concentration.

The values for weight percent coal in 011 found at each location in the column and its variation with respect to the C. G. drop (or days) are shown in Table 11. The data indicate that the increased

C. G. drop was due to the settling of coal particles in oil as shown by the decrease in coal content at the top and an increase at the bottom as time progressed. For example, at a C. G. drop of 0.75 mm

(1 day after mixture preparation) the percentage coal at the top was

46.8% while at the bottom it was 55.6%. For the same mixture at a

3.5 mm C.G. drop (24 days after mixture preparation) the percentage coal at the top was 7.26% while at the bottom it was 57.7%. 74

TABLE 11

VARIATION IN COAL CONCENTRATION WITH HEIGHT

FOR 50/50 BY WEIGHT MIXTURE OF OHIO NO. 8 COAL -100 MESH IN NO. 6 FUEL OIL AT 25°C

LOCATION OF THE SAMPLE WEIGHT PERCENT COAL AT C.G. DROP OF POINT FROM TOP, 0.75 MM 2.30 MM 3.50 MM DISTANCE IN INCHES (AT 1 DAY)* (AT 7 DAYS)* (AT 24 DAYS)*

o (top) 46.8 33.1 7.26 6 47.7 45.8 51.3 12 47.9 45.6 57.0 16 (bottom) 55.6 56.8 57.7

*For the data of e.G. drop versus days, see Appendix D for Test No.1.

Note: Weight percent coal by gravimetric analysis, accurate within + 0.5%. 75

The variations in coal concentration along the column length at various days are shown graphically in Figure 14. In the figure, zero day indicates the day of sample preparation and due to homogenity of a mixture at this point in time the coal concentration along the column length is shown by a dotted line corresponding a 50/50 mixture. The various curves of Figure 14 were drawn by assuming a gradual change in coal concentration along the column length. The above assumption is approximately valid because experimental data do indicate that for the bottom 2/3rd of the column changes in coal concentration were almost continuous in nature (see Table 11 for the data). The uncertainty lies at the top portion of the column. For example, 24 days after the mixture preparation, the coal concentration at the top was found to be 7.26% by weight and at 6" from the top was found to be 51.3%. It is quite possible that the interface between coal and oil lies in between these two points, the top portion containing almost a particle free oil layer while the bottom portion contains 50 percent or more coal by weight.

To locate" exactly the interface between coal and oil requires microscopic examination of coal particles through the oil. Since the

No. 6 fuel oil used was very dark, all attempts were unsatisfactory.

For example, attempts were made with a laser beam as well as with gamma rays to detect the coal particles in oil, by passing the rays through the coal-oil mixture. However, such attempts were failures primarily due to a very small difference in density between the coal and oil that were used. The other alternative would be to freeze the 0 1 2 ~ :I: 3 0 z 4 '-'- Q. 5 0 I- 6 ~ 7 0 8 AT 0 DAY a: u. 9 8. AFTER 1 DAY w 10 0 G AFTER 7 DAYS z 1 1 -e o AFTER 24 DAYS I- 12 C/) 13 -c 14 15 16 0 10 20 30 40 50 60 PERCENT COAL BY WEIGHl

COAL CONCENTRATION versus HEIGHT ~ (J) FIGURE 14 77

settling tube containing the coal-oil mixture and cutting it into small sections. Each section then should be studied microsopically and anlyzed for the coal content gravimetrically, to study the details of the settling phenomena.

To help understand the settling behaviour of coal particles in highly concentrated suspensions, coal particle size photographs were taken. As mentioned in the previous chapter, after gravimetric analysis the resultant coal particles were used for the microscopic observations. The particle size photographs were taken for the

samples collected at one day after the mixture preparation and also at 24 days after the mixture preparation for the same mixture.

The coal particle photographs for the samples collected at one day after the mixture preparation at the top and bottom of column A

are shown in Figures 15 and 16 respectively. Figure 15 shows a

large number of small size particles ranging in size from 10-30 micrometers with a few particles of about 60-70 micrometers.

However, Figure 16 indicates that at the bottom of the column there

we~ a large number of relatively large size, about 100-150 micrometers, particles with a very few small size particles. These

findings show that even in a highly concentrated coal-oil mixture at

25°C, large particles did settle out first due to gravitational force.

The coal particle photographs for the samples collected at the

top and bottom of the column C at 24 days after the mixture prepara­

tion are shown in Figures 17 and 18 respectively. Figure 17 shows ._------

7~

COAL PARTICLES AT TOP OF. TUBE,

1 DAY AFTER THE MIXTURE PREPARATION (x 100).

NO.8 C 0 A L ( - 1 0 0 MESH) J NO.6 0 I L J A T 2 5 °C.

FIGURE 15

COAL PARTICLES AT BOTTOM OF TUBE,

1. DA Y AFTER THE MIXTURE PREPARATION (x 100). NO.8 C 0 A L ( - 1 0 0 MESH ). NO.6 0 I L, AT 25°C.

FIGURE 16 79'

COAL PARTICLES AT TOP OF TUBE, (x100). 24 DAYS AFTER THE MIXTURE PREPARATION

NO.8 C 0 A L ( - 1 0 0 M ESH ). NO.6 0 I L, AT 25°C.

FIGURE 17

COAL PARTICLES AT BOTTOM OF TUBE, (x100). 24 DAYS AFTER THE MIXTURE PREPARATION 0C. NO.8 COAL(-100 MESH), NO.6 OIL AT 25

FIGURE 18 80

very small size particles ranging in size from 1 to 10 micrometers while Figure 18 shows a large number of larger size particles of about 100-150 micrometers in diameter. These findings indicate that as the settling continued (for 24 days) additional smaller size particles also travelled down to the bottom and accumulated over the larger size particles that had been already settled, leaving an almost particle free oil layer at the top.

The results presented in Table 11 show that as the settling continued the pendulum apparatus showed a continuing C. G. drop. It also shows that as the C. G. drop increased the weight percent coal at the top decreased while at bottom it increased. The data indicate that the pendulum can be used to detect the settling of coal particles in oil. It was then decided to establish the relationship between c. G. drop and the coal concentration profile for the mixture.

Figure 19 shows the relationship between the drop in C. G. and percent coal by weight in the mixture at the column top, 6" from the

top, 12" from the top and at the bottom (16" from top). The idea was

that if the C. G. drop for a given mixture is known then one can use

the graph to find the weight percent coal at various locations by drawing a horizontal line corresponding to a particular C. G. drop value. It is important to note that the rate at which the C. G. drops is time dependent. When a C. G. drop occurs, settling

definitely occurs and one can get the change in concentration profile

in the column from the data in Table 11. The discussion 1s now aimed

at establishing c rlteria when one can or cannot use the correlation

presented in Figure 19. 4

3 ~ a: w .... w ~ -.J .J 2 -~ '-' C- O I 0 AT TOP a: Q. ~ 6/1 FROM TOP CJ . A 1 2'1 FRO M TOP 0 1 1 m AT BOTTOM

o o 10 20 30 40 50 60

PERCENT COAL BY WEIGHT

RELATIONSHIP BETWEEN e.G. DROP and COAL CONTENT en FIGURE 19 82

It was expected that the variation in coal content or coal particle size distribution along the column length for mixtures would depend upon the type of coal, type of oil, temperature, percent coal in oil, particle size distribution of the coal used, and other factors affecting the surface properties of the coal. The drop in e.G. represents an overall effect of the density change along the column length that has been developed due to the settling of coal particles in oil. Therefore, the graphical correlation shown in

Figure 19 will be valid only for the same type of coal and oil used with the following assumptions:

1. All coal-oil mixture samples are placed in identical tubes

with identical sample length (i.e., amount of sample used

for each tube should be about the same).

2. Particle size distribution of the coal used is the same for

all samples.

3. Surface properties of the coal used is the same for all

samples.

4. Settings of the pendulum apparatus is kept the same once the

study has been started using the freshly prepared mixture.

Assumption number 1 requires that the C. G. drop should be measured for a fixed length of sample. If the length differs then the e.G. drop will be a different number. Assumption number 2 requires that the coal particle size distribuion should be the same

(even though particle size may differ from one sample to another).

If the size distribution is different then the formation of different 83

density zones may resul t , For similar reasons, asumption number 3 requires that the coal surface properties should be the same for all samples. Stability studies reported by others (11,17) suggest that these two parameters affect the settling behavior of coal in heavy oil. In assumption number 4, the setting of the pendulum apparatus theoretically does not affect the C. G. drop value. However, if the setting is changed in between readings then the accuracy of the period measurement is changed and that will introduce an additional error into the C. G. drop value.

If two samples were prepared with the only difference being that their stabilities were evaluated at different temperatures (one at

25°C, the other at 60°C), then at the higher temperature the settling of the coal particles in oil will be accelerated. If this is the case, then, graphical correlation of Figure 19 can be used to find the variation in coal concentration along the column length without doing the time consuming gravimetric analysis for the same type of coal-oil mixture.

To show how the particle size distribution affects the settling, coal-oil mixtures having the same type of coal and oil (No. 8 coal,

No. 6 oil) but with different size range particles than in the previous case were prepared. One mixture was placed in a settling tube P8 (stability test No.4) and one in the coal-oil mixture column

G (valve set G). The particle size distribution for the coal particles used for this mixture Is shown in Figure 8 (page 53) by curve AI, having a size range of -325 mesh size. 84

When a C. G. drop of 1 mm was observed by the pendulum apparatus for the tube P8, the valves of set G were closed. Samples collected from the valves Gl, G2, G3 and cap G4 were analyzed for the coal concentration gravimetrically. The values for weight percent coal in oil found at each location in the column are shown in Table 12.

Table l2-r indicates that at a C. G. drop of 1 mm about 10 percent by weight coal was found at the top. Coal concentrations at other locations in the column were a little above 50 percent. Using

the graphical correlation of Figure 19 (page 81) at a C. G. drop of

1 m.m the weight percent coal at the top was expected to be 45 percent.

The difference may be due to the relatively uniform size coal par­

ticles used for the present mixture compared to the previous ones.

The particle size used here was about 90 percent passing through 325 mesh screen with an average particle size of about 30 micrometers.

Particle size photographs for the samples collected at the top and bottom of the column G are shown in Figures 20 and 21 respec­

tively. Figure 20 shows about an euqal proportion of large (40-50

micrometers) to small size particles (10-20 micrometers). However,

Figure 21 indicates that at the bottom of the column G there are some

very small size particles (5-10 micrometers) and a few large size

(60-70 micrometers) particles. These findings suggested that most of

the coal particles travelled together and possibly formed a clear

interface between coal and oil as a result of settling. In other

words, due to the small and uniform size coal particles used here, 85

TABLE 12

VARIATION IN COAL CONCENTRATION WITH HEIGHT

I. FOR 50/50 BY WEIGHT MIXTURE OF OHIO NO. 8 COAL -325 MESH IN NO. 6 FUEL OIL AT 60°C

LOCATION OF THE SAMPLE WEIGHT PERCENT COAL AT POINT FROM TOP, e.G. DROP OF 1.01 MM (AT 12 DAYS)* DISTANCE IN INCHES

o (top) 10.5 6 53.6 12 51.6 16 (bottom) 51.1

*For the data of C.G. drop versus days, see Appendix D for Test No.4.

II. FOR 50/50 BY WEIGHT MIXTURE OF SOLID SOLVENT REFINED COAL -50 MESH IN NO. 6 FUEL OIL AT 25°C

LOCATION OF THE SAMPLE WEIGHT PERCENT COAL AT POINT FROM TOP, e.G. DROP OF 0.82 MM (AT 32 DAYS)* DISTANCE IN INCHES

o (top) 48.5 6 48.8 12 49.3 16 (bottom) 48.5

*For the data of e.G. drop versus days, see Appendix D for Test No.5.

Note: Weight percent coal by gravimetric analysis, accurate within + 0.5%. COAL PARTICLES AT TOP OF TUBE,

12 DAYS AFTER THE MIXTURE PREPARATION (x 100).

NO.8 C 0 A L ( - 3 25M ESH ). NO.6 0 JL, AT 60°C.

FIGURE 20

COAL PARTICLES AT BOTTOM OF TUBE, 12 DAYS AFTER THE MIXTURE PREPARATION (x100).

NO.8 C 0 A L ( - 3 25M ESH) t NO.6 0 I L, AT 60°C.

FIGURE 21 87

the hindered settling effect was more pronounced and the settling behavior of the coal was different from the previous case.

An attempt was also made to develop a correlation between the

C. G. drop and the variation in coal concentration along the column length for the solid SRC l/No. 6 fuel oil (SOM) mixture. A 50/50 mixture of SRC l/No. 6 oil was prepared and placed in settling tube

P4 (stability test No.5) as well as in column D. The particle size distribution for the SRC used is shown in Figure 9 (page 55) by curve

F having a size range of -50+100 mesh.

SOM was much more stable than COM of equivalent composition as measured by a very small C.G. drop after a period of about a month.

At the end of 32 days when a C. G. drop of 0.82 mm was observed for tube P4, valves of column D were closed and captured samples were analyzed for the SRC I concentration. The values for weight percent

SRC I in oil at each location are shown in Table 12-11. The SRC I concentrations from top to bottom was found to be about the same within the range of 48 to 49 percent SRC I by weight.

The values shown in Table 12-11 for SRC/oil mixture are a little less than 50 percent value, which was due to the gravimetric procedure employed to extract the oil. In the gravimetric procedure for SRC-oil mixture, kerosene at room temperature was used to extract the oil (for details of the procedure used see Appendix B). It was found that kerosene does dissolve a very small amount of SRC at this temperature.

Previously, attempts were made to separate oil from SRC using toluene.

However, when toluene was tried results were erroneous, for 50% solid 88

SRC in oi.l, a value of only 30% was obtained and, a mild solvent, such as kerosene, was used.

Particle size photographs for the samples collected at the top and the bottom of column D are shown in Figure 22 and 23 respectively.

Figure 22 shows an equal proportion of different size coal particles indicating a very broad particle size distribution. Figure 23 shows that after 32 days of settling there were large amounts of small size particles (20-30 micrometers) and only a very few large size (100-150 micrometers) particles.

Since the particle size distribution used for the mixture was very broad and the SRC-oil mixture was stable, no definite pattern for the variation in particle size with height could be found. 89

.SRCI PARTICLES AT TOP OF TUBE,

32 DAYS AFTER THE MIXTURE PREPARATION (x 100). SOL IDS R C ( - 5 0 M ESH ), NO.6 0 I L, AT 25°C.

FIGURE 22

SRC! PARTICLES AT BOTTOM OF TUBE,

32 DAYS AFTER THE MIXTURE PREPARATION (x 100) SOLIDS R C ( - 5 0 M E S H ), NO.6 0 I L, AT 25°C.

FIGURE 23 90

Tuned Circuit Detector:

The original circuit consisted of 8 coils, the output of which was connected to an XY plotter. Experiments were carried out by dropping 1/8" diameter steel balls through various coal-oil mixtures.

The mixtures with 40, 50 and 55 weight percent Ohio No. 8 coal in No.

6 fuel oil were tried. For each mixture, the XY plotter output was

repeated many times using different steel balls. Two typical outputs are shown in Figure 24 for No. 6 oil and 50/50 mixtures of No. 8

coal/No. 6 oil at room temperature.

Due to the noise associated with the circuit and the XY plotter

the experiments were not repeatable. For No. 6 oil or freshly pre­

pared mixtures, the output showed variations in peak to peak distance with no definite trend. There was no definite trend observed for the

noise associated at each turn when different percentage coal in oil

suspensions were tried. It was thought that the part of the problem

can be due to the fact that B-B' s (1/8 It dia sphere) used were not

exactly spherd caI or each turn was not placed exactly at I" distance

apart. These problems and others involving the circuit and the XY

plotter were solved by building a new experimental setup.

The new circuit consisted of 16 coils spaced at 1 inch

intervals. The output was connected to a crystal controlled XY

plotter (for description see previous chapter). Experiments were

started using a plain No. 6 011 placed in a glass tube with the oil

level 1" above the first coil. The small ball bearing was then

released slowly from the surface of the liquid. To repeat the experi- t' , ~ \'T j---i f "T ! ; \ ; ;.... i . t Nf\.Jn A j)J 1\1f\J~Ol~A t21°c j I \ I ; 1 I '._~4C-H_A;RI$~N:.EE~_ -~..------_._.~..::.-'.,,-_..JL.;----:-----j--.-- f"' __ ~~0 2 I NVS .. ~~-~~-.1- - i·-j··· :..! I , i : ! ! -, III ! :------r--·---l-·/~~~I·--·:.., r-'l-~'--I~'-'/j-t·_-,.._-t-\~--!._.-!-"!.! a.;

'-~~'I' ~lI.'t~ .'-----1'-_.- • • .•. iA'i :Ali' ',: ! : I:,.. ! I . • I. ; : . J I I , : ~ lit., I I I, I :--1- ---: I -r--'T---i- - (--, I" .- ; -- ._.1-_ , ., I \ IJ Ii ! . 'r' . ! V! '" -_.--.J---L i i--j------i,-.:~4{L~t~TUB,EAT 25°C r>:

. I.' i,•.·. IAFTi;'.ER 2 .D~,.YS:,. .,. "

~ ~ I .. i . !,!! i !.- -. _· __·· .. ··t·_·'I!",'.I__· {,,···_-t-- ''---''FHAjR'T ·.:ttl.."SPEED 0.2, INlSEC-- I ; ! l , I I Ii, ,. j l

CURVES FOR AN ORIG I NAL CIRCUIT FIGURE 24

\D~ 92

ment additional identical ball bearings were released one by one and the output for each was recorded on the XY plotter as shown in Figure

25. In Figure 25 the peak to peak distance in the X direction indicates the time required for the sphere to travel one inch distance.

A freshly prepared 40% COM (40% by weight Ohio No. 8 coal in

No.6 oil) was placed in another glass tube with the mixture level I" above the first coil. One hour after the mixture preparation, a small ball bearing was released from the surface and the output was recorded on the XY plotter. The experiment was repeated five times

(each time dropping a new ball bearing) using a XY recorder chart speed of 20 in/min and then again repeated five times using a chart speed of 50 in/min. One of the graphs is shown in Figure 26.

Eight hours after the mixture preparation (for 40% COM), the experiment was repeated in the same manner. Similarly, 2 days after the mixture preparation, the mixture was tested. The XY plotter graphs for 8 hours and 2 days period are shown in Figure 27 and 28 respectively. During the entire test the glass tube was kept inside the coils, the circuit was on all the time and XY plotter was turned on one hour before the time of measurement.

Peak to peak distances for all the graphs obtained for 40% COM were measured (data given in Appendix E). One hour after the mixture preparation it was expected that the sphere should take the same time

(assuming it has reached its terminal velocity) in traveling from coil to coil, because the mixture was uniform (coal-oil mixtures do 93

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CURVE FOR 40% COM AFTER 1 HR

FIGURE 26 \.0 +:» 95

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not show any significant e.G. drop for an initial 1-2 hour period as measured by the pendulum apparatus). Some graphs for the 1 hour period agreed with one another for some coils but most of them showed a difference for the first 2 coils at the top and the last 2 turns at the bottom. After 8 hours of time if any settling has occurred then the steel sphere should take a longer time to travel between coils near the tube bottom. Some graphs showed this but it was not always repeatable (see two curves in Figures 27). Similarly, graphs for the

2 day period (Figure 28) also showed a random difference in the peak to peak distance.

As a result, it was decided to use a homogeneous solution to check for possible instrument error. For this purpose a glycerine solution and a Brookfield viscosity standard (having a viscosity of

116 P at 25°C, comparable to that of 50% COM) were used. Experiments were carried out by varying the XY recorder chart speed as well as liquid level above the first coil. Each experiment was repeated five times using the same weight and diameter (1/8" ball bearings) spheres. Data for these findings are given in Appendix E. Data are reported as the time (in milliseconds) required for the sphere to travel between each successive coil, its mean value for five observations and its standard deviation.

Data for a glycerine solution wi th liquid level of I" above the first coil and a chart speed of 20 in/min indicate that the mean time required for a sphere to travel between coils varied from 460 milli­ seconds (coil no. 1 to 2) to 694 milliseconds (coil no. 11 to 12). 98

The variation in time was about 50%, which was a very big variation.

Since the glycerine solution was uniform it was expected that the sphere should take the same time in passing between each coil. The data also show that deviations in 'mean time' were random in nature.

It was then decided to collect the data at a XY recorder chart speed of 50 in/min (for data see Appendix E). One of the charts from

the XY recorder is shown in Figure 29. In this case the mean time

required for the sphere to travel between coils varied from 449 milliseconds (turn no. 1 to 2) to 667 milliseconds (turn no. 11 to

12). The variation in time now was about 48%. These findings

indicate that the chart speed was not a factor for the variation.

The deviation in 'mean time', was also random in nature.

In both of the above cases the time required for the sphere to

travel between the top two coils was different from the others This

could have been due to the sphere not reaching its terminal velocity.

To check for this, experiments were carried out with a glycerine

level of 4" above the first coil (increasing the level) and a chart

speed of 20 in/min and then at 50 in/min. Data for these findings

are given in Appendix E. With a chart speed of 20 in/min the 'mean

time' varied from 764 milliseconds (coil 1 to 2) to 843 milliseconds

(coil 6 to 7) while using a chart speed of 50 in/min the variation

was from 755 milliseconds (coil 1 to 2) to 846 milliseconds (coil 9

to 10). One of the charts from the XY recorder is shown on Figure 30.

In both of the above cases the variation in 'mean time' was about I j 99 J

0° LO C\I f- -c W Z a:- 0) w C\J o W >- a: ..J ::> C) C) a: -u, 0 LL.

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0° LO --.f-- C\I I- « W Z 0 -a: C') w w o a: > ::::> ..J CJ G -LL a: 0 LL I ! W I --I I I > ! I- a: I t ~l- ::;) i I·· _- I I 0 I r I t·

... - ~ I I I , , ,I 1 ! I I I 1 I 101

10-12% which was considerably lower than the previous two cases

(48-50% variation) when the liquid level was only an inch above the top coil. These findings indicated that increasing the liquid level above the first coil decreases the variation, particularly for the first two coils. This may be due to "the fact that sphere reached its terminal velocity before passing through the first coil.

It was then decided to test the apparatus wi th a more viscous solution comparable in viscosity to a coal-oil mixture. For this purpose a Brookfield Viscosity Standard (having a viscosity of 116 poise at 25°C) comparable to that of 40% COM was used. A liquid level of about 4" from the first coil was used and data were collected at a chart speed of 1 in/min and then at 2 in/min. For data see Appendix E. One of the charts from the XY recorder is shown in Figure 31.

Data for the chart speed of I in/min indicates that the 'mean time' varied from 10453 milliseconds (coil 1 to 2) to 11386 milli­ seconds (coil 2 to 3) but when using the chart speed of 2 in/min it varied from 10228 milliseconds (coil I to 2) to 11504 milliseconds

(coil 3 to 4). So the variation in 'mean time' was about 9 to 12% for this solution. The variations in the time were a little less than for the previous case of glycerine solution. Note that the time

required for the sphere to travel one inch distance through the solu­

tion was an order of magnitude greater than for the previous case.

Data also show that the deviation in 'mean time' was random in nature.

The results for all these experiments indicated a 'mean time' .. I I I ! I • __ :•.__ .1. _ I1 !, JI I .l..!_...L._.1. _•••"..' _ •• • I r ..i~..., _ _ f--t-.! I I ,.. I 1 j I· 1- I, , , i --1__ I l. ..-I .! .. -l-.. __ . I '." ' '.""...,. . I _ i--'--~_I I._ ..'.. __/ ..t-.\---f\-;~I-"(\ r~---/~'i\--l'{\!\ I '.. -t.. _- +-;:-- . l \ /1\ (\ .!. I .t fl ... I"" '. , '...... _ \ . .'>: ,) l :, \ i \ i..l' ,.I J ~J \.l--·'j··i·· t : \ i .'J.:\'/ .__L ..... } \ ,- i I I ! i _..~~.\_-_.._.- _,_ I !\ I 1: I . I~._~!.'---"-~"--'-"T-'-~II ! . !,

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CUR VE FOR AV IS COS ITYSTAN 0 A R 0 A T 25°C '0 N FIGURE 31 103

variation of 10% when a liquid level of 4" above the first coil was used. Considerable time and efforts were made to identify all possible causes of variations. It is most likely that the problem was with the circuit itself.

Note that there was an order of magnitude difference in 'mean time' when the solution was changed from glycerine to a Brookfield viscosity standard. So this 10% variation in 'mean time' will not be a problem in detecting the difference between a 50% coal-in-oil mix­ ture and oil because of the large difference In viscosity. However the problem would be in detecting the few percentage differences of coal in oil in the region of 50 to 58% coal by weight. Here the difference in the timing observed due to a concentration gradient along the column length would be comparable to those introduced by the apparatus. Gravimetric analysis for the 50% COM (previous section) indicated that for the bottom 2/3rd of the column, the variation in weight percent coal was about 8-10% wi th a maximum concentration of about 58% coal by weight at the bottom.

Data for the 40% COM show the misleading information resulting from this apparatus and data using glycerine and a viscosity standard solution show a random variation in the 'mean time.' It was then concluded that use of this apparatus would produce misleading findings of coal concentration variation along the column length.

Further experiments were not carried out. If any further experiments are to be carried out, it is recommended to modify the circuit. 104

Viscosity of Coal-Oil Mixtures

Viscosity data for oil and coal-oil mixtures were taken with a

Brookfield RVT model viscometer. Data were taken when the material was subjected to a constant shear rate (corresponding to a certain spindle speed) over a period of time as well as with varying spindle speeds.

Viscosity data for No. 6 fuel oil at 25°C using spindle No. 1 are presented in Appendix F. Data show a viscosity value of about 2 poises. When the No. 6 oil was subjected to a constant shearing rate corresponding to 2.5, 5, 10 or 20 RPM of the spindle over a period of time it did not show any change in viscosity value. This indicates that the No. 6 fuel oil used did not have any shear thinning or thickening characteristics. The data also show that when the spindle speed was successively doubled from 2.5 RPM to 5, 10 and 20 RPM, the dial readings were also doubled. As a result, the viscosity value remained about the same (2.12 to 2.22 poise). These findings indicate that the No. 6 oil used was Newtonian in character.

Viscosity data for the suspension of 20, 40, 50 and 55 percent by weight No. 8 coal in No. 6 fuel oil (COM) at 25°C are presented in

Appendix F. The coal particle size used for the mixture preparation was -200 + 325 mesh size. The specific observations that can be made from these viscosity data are as follows.

20% COM showed a viscosity value of about 5 poises at 25°C. When the material was subjected to a constant shearing rate over a period 105

of time, it showed relatively no change in the viscosity value. The data also show that when the spindle speed was successively doubled from 2.5 RPM to 5 and 10 RPM, the dial readings were almost doubled in value. Data also show that for this mixture the viscosity value was increased with the sample age which could be due to the settling of coal particles in oil. The change in viscosity value with the sample age is more important than its trend (increase or decrease) because the trend also depends on the geometry of the spindle used and its location inside the mixture. The change in the viscosity value with time did indicate that there was some change involved in the static coal-oil mixture with time, possibly a structural rearrangement or settling of coal particles in oil.

40% COM showed a viscosity value of about 30 poises at 25°C. The data show that when the spindle speed was successively doubled from

2.5 RPM to 5, 10 and 20 RPM the dial readings were a little less than doubled. This was more true when data were taken 1 day after the mixture preparation. These findings indicate that 40% COM at 25°C had a nominal non-Newtonian characteristic. When the material was subjected to a constant shear rate for a longer period of time it did not show any change in its viscosity value (this fact not shown in the data).

50% COM showed a viscosity value of about 210 poises at 25°C.

Data show that when the spindle speed was increased from 2.5 to 5 RPM viscosity values were decreased, showing a shear thinning charac­ teristic of the material. The data also show that when the material 106

was subjected to a constant shear rate over a period of time, it showed a slight decrease in the viscosity value.

Interestingly, 50% COM showed an increase in viscosity value up to 1 day after the mixture preparation and thereafter the viscosity started to drop down for the period of about the next 15 days. How­ ever, when viscosity was again measured at the end of 30 days it showed a value less than that of the freshly prepared 50/50 mixture.

Such a trend in viscosity variations indicates that either internal structural changes or settling of coal particles in oil or both have taken place with the sample age. It is not very clear from the data which one of the above was taking place at what time. A stabil:f.ty study for this 50/50 mixture indicated that settling of coal particles did not occur within a day or two after the mixture preparation but it definitely occurred after a period of 15 days. These findings sug­ gest that for the initial one or two day period changes in viscosity of coal-oil mixture could be due to the internal structural rearrange­ ments. This fact shows also that 50% COM was thixotropic in nature.

55% COM showed a viscosity value of about 480 poises at 25°C, which indicated that on increasing the weight percent coal from 50 to

55% the viscosity of the mixture increased by a factor greater than

2. Data show that when spindle speed was doubled (from 2.5 to 5 RPM) the viscosity of the material decreased. Data also show that the viscosity of this mixture increased wi th the sample age. Note also that when 55% COM was subjected to a constant shear rate correspond­ ing to 5 RPM for a longer period of time, it showed first a decrease 107

(up to about the first 40 spindle rotations) and then showed an

increase in its viscosity value. This can be characterized as the

thixotropic breakdown of the material with time (45). This breakdown was successively less pronounced for 50% COM and was almost

negligible for the 40 and 20% COM mixtures.

To see how the particle size affects the COM viscosity a 50/50 mixture of No. 8 coal/No. 6 oil was prepared with a particle size of

-100 +200 mesh size (coarser than the previous case). This coal-oil mixture showed a viscosity of about 110 poise, which was substantially

less than the value of 210 poise obtained for 50% COM using a

particle size range of -200 +325 mesh size. For the viscosity data

see Appendix F. These show that keeping other variables constant,

viscosity of the coal-oil mixture increases with an increase in the

particle fineness. This could be due to the greater interference

between small size particles than the large ones, because the smaller

the diameter of the particle the larger will be the surface area per

unit concentration of coal. Data also show that the viscosity of

this coal-oil mixture increased substantially with the sample age

which could be due to the increased settling rate of the large size

coal particles.

To see how the temperature affects the viscosity of 50% COM a

test was conducted at 60°C. The coal particle size used was -200

+325 mesh size. For the viscosity data see Appendix F. Viscosity of

50% COM at 60°C was about 18 poise (compared to a value of 210 poise

at 25°C). This showed that the viscosity of the coal-oil mixture 108

decreased rapidly with an increase in its temperature. Data also show a very large increase in the viscosity of the material with the sample age, which could be due to the increased settling of coal particles through oil at elevated temperature.

Viscosity data for the suspension of 15, 30, 40 and 50 percent by weight suspension of solid Solvent Refined Coal (SRCI) in No. 6 oil at 25°C are presented in Appendix G. These mixtures are referred to as a SOMe The SRC I coal particle size used for the mixture prepara­ tion was -200 +325 mesh size. The specific observations that can be made are as follows.

15% SOM showed a viscosity value of about 5 poises at 25°C. The data show that when the spindle speed was successively doubled from

2.5 RPM to 5 and 10 RPM the dial readings were almost doubled in value. Also, when this material was subjected to a constant shear rate for a period of time it did not show any change in its viscosity value (this fact not shown in data). These findings indicate that

15% SOM mixture was Newtonian in character (about the same as No. 6 fuel oil). Data also show a slight increase in the mixture's viscosity when it was measured after 1 day, which could be due to the structural changes that may have occurred after the mixture preparation.

30% SOM showed a viscosity value of about 25 poises at 25°C. The data show that when the spindle speed was successively doubled from

2.5 RPM to 5, 10 and 20 RPM the dial readings were a little less than doubled. This was more true when readings were taken 1 day after the 109

mixture preparation. This showed that with 30% SRC I in No. 6 oil, the mixture developed some non-Newtonian characteristics.

40% SOM showed a viscosity value of about 70 poises at 25°C.

Here also the viscosity decreased when spindle speed was successively doubled from 2.5 to 20 RPM but the amount of decrease was less than the previous case (30% SOM). Data also show the increased viscosity after 1 day, which could be due to the structural changes involved through the coal-oil mixture as mentioned before.

50% SOM showed a viscosity value of about 700 poise at 25°C, showing almost a tenfold increase in SOM viscosity on increasing the weight percent SRC from 40 to 50 percent. Data show that when spindle speed was successively doubled from 2.5 to 20 RPM the mixture's viscosity was considerably decreased. This indicated some kind of structural breakdown of the mixture with shear, i.e. the mixture showed shear thinning characteristics. The data also show a decrease in the mixture's viscosity for the first 3 days and then an increase up to about 8 days. This behavior can not be explained from the present investigation. It could be due to structural rearrangements occurring after the mixture's preparation or could be due to the geometry of the spindle used and its location inside the mixture.

Note that a random change was also noticed for the 50% COM.

The rheological properties of coal-oil mixtures, i.e. COM as well as SOM, that can be concluded from the previous discussion are as follows. 110

For finely divided coals in heavy oils the viscosities of the suspension were found to rise markedly in the region of 40 to 50 percent coal by weight. The data in Table 13 show this. These data were then plotted as viscosity in poise versus weight percent coal in oil and is shown on Figure 32. The figure shows that the viscosity increased rapidly above 40 percent coal in oil and this increase was larger for SOM than for COM. The fact that 50% SOM was much more viscous than 50% COM was also reflected in their stability studies,

i.e. 50% SOM was more stable than 50% COM. The nature of these curves also indicate that the stability of coal-oil mixtures can be increased just by increasing the coal-content above 40 or 45% coal by weight, probably due to the increased particle-to-partic1e

interactions.

Most of the coal-oil mixtures tested showed an increase in viscosity with sample age. This increase in viscosity can be

interpreted in terms of stability of coal-oil mixture. T. T. Coburn

(13) used the relation of the form

10g(Apparent viscosity) = a log(Spindle speed) + b

and related the term 'a' to the stability of coal-oil mixture.

It was then decided to use the above relation to interpret the

viscosity data. For the data see Appendix F and G. The logarithmic

plot of apparent viscosity versus spindle speed is shown in Figure

33. The data were plotted for the mixture of COM as well as SOM.

T. T. Coburn related the value of 'a' to the weight percent

solids along the column length. However in the present investigation 111

TABLE 13

DATA SHOWING THE VARIATION IN VISCOSITY OF COAL-OIL MIXTURES WITH THE COAL CONTENT

BROOKFIELD VISCOSITY IN POISE * % COAL BY OHIO NO. 8 COAL-NO. 6 OIL SOLID SRC-NO. 6 OIL WEIGHT (COM) (SOM)

15 5.2

20 4.64

30 24.8

40 27.2 73.6

50 212.8 784.0

55 489.6

*Values indicate the viscosity of freshly prepared coal-oil mixtures at a spindle speed of 2.5 rpm. The readings were noted after 10 spindle rotations (i.e. 10/2.5 = 4 mins. after starting the viscometer motor). For details regarding the viscosity values and the spindle used, see Appendix F and G. I JZ

800

SOLID SRC-NO.6 OIL 700 _ MIXTU REA T 25°C

EE Ef) points interpolated from 600 log-log plot of viscosity versus percent coal w UJ o 500 . Q. NO.8 COAL-NO.6 OIL Z MIXTU REA T. 25°C > .... 400 UJ o o fI) > 300 ..

200.

100

,10 20 40 50, PERCENT COAL BY WEIGHT

FIGURE 32 VISCOSITY versus PERCENT COAL 4 _. ..1._ ~ . l ._.•.. 4 .

3 -·--·-r~-r--:

__ : ~.- ~_ :60 $ ·0 0 M AFTE R 2

100 UJ en o- A- I > t- -en o o tn -> I­ Z W a: 10 ...... " :0 6 5 CIt COM IMMEDI ATE -e .._- --_.. -. - .- :... ~._~ .(partlcles -200 mesh) G­ o. ~ ---.. ,.-,- .. - ' .. -., "-(4' 65.. c 0 M AFTER"2 DAYS 4( '-'--"- ,"-..~. --..-. - -+-._ ... -_._..- . + i :.J .. d;-~'~~j j~jJ-'-:---:'~ -:I _ I .- 4 ~- .__":_;._.._-_. -1_:.: . ~- _.. ...- "-' + ~_.- - --_._~ -- _.' , ..•, -. __.•_- L:~:r~_:1: : i: '. 'ijj 1 1: .,... .: .. t .: :. 3 -,-- ~ -:-ci----C?--'-;-'-_.. --jj(flto ·e~u ei 0 i I

~ .,- i ....~ _-t ..... j~ . J, ,-- I - : '1 -! 1 . t------+---- i .. - . j1 - j . ! .; 1 --._ - j - - .- ,.. .. J. • I . 1 i - t .,. - -- -!. - -e - 1• .. 1 - y • : • r 1 1 :• 1 I \ I, , I I 4 ~ 6 7 E S ,../ i. 1 10 20 100

SPINDLE SPEED RPM

APPARENT VISCOSITY VERSUS SPINDLE SPEED FIGURE 33 114

the position of the spindle inside the mixture was fixed during the study, so increases in value of 'a' should reflect the amounts of settling that have occurred. Figure 33 shows that usually the value of 'a' increased with the sample age (increase in the slope). Figure

33 also shows that 2 days after the mixture preparation, the 50% COM showed non-linearity in the logarithmic relationship. This shows that, in addition to the settling of coal particles in oil, some other factors were also affecting the viscosity of the coal-oil mixtures.

The various coal-oil mixtures also showed some kind of shear thinning characteristics i.e. their viscosity was decreased when the shear rate was increased (increasing spindle speed). For the freshly prepared mixtures of 40% COM, 40% SOM, 50% COM and 50% SOM the viscosity data were taken using the spindle No.5, by successively increasing the spindle speed from 2.5 to 5, 10 and 20 RPM and then by decreasing the speed in the reverse order. The data are presented in

Table 14 showing the dial reading at a particular spindle speed for

each mixture. The data were then plotted as the spindle speed in RPM versus dial readings and are shown on Figure 34. Note that viscosity data of 50% SOM were taken with No. 6 spindle (due to its higher

viscosity) and then converted to the equivalent dial readings of the

spindle No.5.

The steep curves in Figure 34 for the 40% SOM, 40% COM and 50%

COM show some loop formations. This finding indicates that these

mixtures were thixotropic in nature. Green H. (45) indicated that the

larger the area of the loop the greater is the thixotropic breakdown. 115

TABLE 14

VISCOSITY DATA SHOWING THE THIXOTROPIC BEHAVIOR OF COAL-OIL MIXTURES AT 25°C

THE BROOKFILED VISCOMETER DIAL READINGS ** TYPE OF COAL-OIL INCREASING THE SPINDLE+ DECREASING THE SPINDLE MIXTURE* SPEED SPEED 2.5 RPM 5 RPM 10 RPM 20 RPM 10 RPM 5 RPM 2.5 RPM

40% COM 1.7 3.7 7.5 14.8 7.2 3.5 1.7

40% COM 4.6 7.8 13.5 23.7 12.5 7.1 4.3

50% COM 7.5 14.5 28.5 50 24.2 12.8 7

50% COM 19.6 30.2 48.9 80 43 24.4 14.7 (49) (75.5) (122.2) (200) (107.5) (60.5) (36.7)

* COM means a mixture of Ohio No. 8 coal/No. 6 fuel oil and SOM means a mixture of solid Solvent Refined coal/No. 6 fuel oil. For all the mixtures coal particle size used was -200+325 mesh.

** All viscosity data are for the freshly prepared coal-oil mixtures, measured immediately after the sample preparation. Dial readings shown here were noted after 10 spindle rotations (at each given speed) •

+ Except for 50% SOM mixture spindle no. 5 was used. For 50% SOM spindle no. 6 was used.

() Values in parenthesis indicate the equivalent value of dial readings for 50% SOM if it had been obtained by spindle no. 5. 20

18

16

:E Q. 14 a: c 12 w UJ Q. 10 I 1 U rJJ .>: ,/' 0 40% COM en I I n E9 40% SOM w 8 II /' /' ..J -- ...... ,..,.../ C II o EB 50% COM z I I II / Q.- 6 T11/ ..LI ~ A/UP CURVE 8£ 50% SOM UJ 4

2 o o 10 20 30 40 50 60 70 80 90 100 (150) (200) DIAL READING

THIXOTROPY: Dial Reading versus Spindle Speed for Coal-Oil Mixtures

FIGURE 34 (J) 117

Figure 34 indicates that 40% COM was not thixotropic in nature while

40% SOM and 50% COM showed some thixotropy. The largest loop area was shown by the 50% SOM indicating considerable thixotropic break­ down of this material compared to the others. This fact, when compared with the stability results for these mixtures which indicates that SOM was more stable than COM of equivalent compsition, suggests that the greater the area of the thixotropy loop, the greater is the mixture's stability.

The thixotropic nature of the coal-oil mixtures has been

investigated in the past by Barkley e t s a l , (8) and more recently by

Dooher et.al (14) and by M. Yamamura et.al. (48). The study done by

M. Yamamura contradicts the findings here, they reported that the smaller the area of hysteresis loop, the greater is the COM storage stability. Presently. the SRC I -oil mixtures were found to be more stable than COM, at the same time showing a larger thixotropic breakdown with the shear rate.

Density of Coal-Oil Mixtures

Density of coal (both No. 8 and SRC I), No. 6 oil and the different coal-oil mixtures (COM as well as SOM) were determined by the procedure mentioned in the previous chapter. Density data are presented in Table 15. Density determinations were made at room temperature (25%) 8S well as at 60°C.

The density of No. 8 coal at 25°C using methanol was found to be

1.408 gms/cc, while that of SRC I it was 1.280 gms/cc. This indicates 118

Table 15

DENSITY DATA

DENSITY IN GMS/CC DESCRIPTION At 25°C At 60°C

Ohio No. 8 Coal, particle size -200+325 mesh, using methanol 1.408 using No. 6 fuel oil 1.356

Solid solvent refined coal, particle size -200+325 mesh, using methanol 1.280

No. 6 fuel oil 0.984 0.958

30% COM* 1.1051 1.0782 (1.082)

50% COM 1.1527 1.1381 (1.158)

20% SOM** 1.0441 1.0251 (1.032)

40% SOM 1.0813 1.0756 (1.084)

* 30% by weight suspension of Ohio No. 8 coal (-200+325 mesh) 1n No. 6 fuel oil.

** 20% by weight suspension of solid solvent refined coal, SRC I (-200+325 mesh) in No. 6 fuel oil.

() values in parenthesis indicates a density value calculated by

(density)-l • ~ % wti/100 x (density}f t where density of No. 6 oil used was 0.984 gms/cc & that of Ohio No. 8 coal and SRC I was respectively 1.408 gms/cc and 1.280 gms/cc 119

that Solvent Refined Coal was lighter than the No. 8 coal. Data also indicate that the density of No. 8 coal in No. 6 oil (suspending fluid for the mixture) was found to be 1.356 gms/cc, a little less than the value obtained by using methanol (1.408 gms/cc).

The density of No. 6 oil at 25°C was found to be 0.984 gms/cc while at 60 0 e it was 0.958 gms/cc. This indicates that the density of the oil was decreased by about one percent on every fifteen degree temperature rise. Table 15 also indicates the density values for the various percentages of No. 8 coal/No. 6 oil (COM) as well as SRC l/No. 6 oil (SOM) mixtures. Density data were then plotted as the density (grams/cc) versus weight percent coal in the mixture both at

25°e and at 60 o e . Figure 35 shows these curves.

As a general trend, Figure 35 shows that the density of COM was higher than SOM of equivalent composition at all temperatures.

Figure 35 also shows that the decrease in density of COM was higher than SOM when temperature was increased from 25 to GO°C. This was more true at coal concentrations of greater than 30 percent by weight.

A good estimate of the density of coal-oil mixtures can be predicted by the formula of the form,

-1 % Wt i (density) =::£ t 100 x (densitY)i

In Table 12 the values shown in parenthesis were calculated using the above formula. The density predictions for the mixtures were within 120

1 .1 5

8.J COM AT 25°C

GJ COM AT 60°C

~ SOM AT 25°C 0 o 1 . 1 0 ...... 0 SOM AT 60°C ~ -c a: C) z ....>- 1.05 -en z w c

1.00

NO.6 OIL AT 25°C

OIL AT 60°C 0.95 o 10 20 30 40 50

PERCENT COAL BY WEIGHT

DENSITY OF COAL-OIL MIXTURE FIGURE 35 121

2% of the experimental values. In general, density of both COM as well as SOM showed the expected variations with both the temperature and weight percent coal in oil.

Low-Ash Coal

The objective of the present study was to conduct a laboratory investigation of some alternate methods for producing low-ash coal from different Ohio coals. Two types of Ohio coals were selected,

No. 8 coal and No. 4A coal and experiments were started using phenanthrene at atmospheric pressure. The type of equipment used and procedure that was followed are mentioned in the previous chapter.

The description of the experimental runs and specific observations that were made for each run are presented in Table 16. The principal difficulty in dissolving Ohio coals was that of separating the dissolved coal from the minerals by means of filtration. Several different filtration methods were used in an attempt to obtain a significant amount of filtrate.

Under the conditions of Run No. 3 (see Table 16) a small filterate was obtained. After removing phenanthrene by washing with toluene, the ash content in the product material (by ASTM method) was found to be 1.07% by weight. These findings suggested that phenanthrene can be used to produce low-ash quality coal. However, the yield of the product obtained was very low (only about 7 percent) and from this point in time experiments were aimed at getting an increased yeild of the product. TABLE16

PREPARATIONOF LOWASH COALUSING PHENANTHRENE

DISSOLVER: THREENECKREACTIONFLASKAT ATMOSPHERICPRESSURE.

RUN NUMBER DATE DESCRIPTIONSOF CONDITIONS OBSERVATIONS

1 8/3/79 No. 8 Coal 100 grams, size -10+20 mesh, Everything became solid after a few coal/solvent weight ratio 1:2, reaction minutes of reaction time. time 20 minutes at 330°C. 2 8/6/79 No. 8 Coal 50 grams, size -10+20 mesh, Filtration difficulty i.e. filter coal/solvent weight ratio 1:4, reaction cloth pores were getting time 10 mins. at 330°C. Filtration on choked. a glass fiber filter cloth placed on a heated funnel.

3 8/19/79 No. 8 Coal 30 grams, size -50+100 mesh, Small filtrate resulted. Yield of Low­ coal/solvent weight ratio 1:6, reaction ash material was about 2 grams, i.e. time 30 mins. at 330°C. Filtration on a 7 percent (after removing phenan­ glass fiber filter cloth placed on a threne). Ash content of the product heated funnel. was 1.07% by weight (ASTMD27l-68).

4 10/7/79 No. 8 Coal 25 grams size -50+100 mesh, No filtrate resulted. coal/solvent weight ratio 1:4, reaction time 30 mins, at 350°C. Filtration on W-54l filter paper placed on a heated buchner funnel.

5 10/14/79 Repetition of the conditions of Initially, 2-3 CC of filtrate resulted Run Number 4. and then it stopped. TABLE 16 (Cont'd)

PREPARATIONOF LOWASH COALUSING PHENANTHRENE

RUN NUMBER DATE DESCRIPTIONS OF CONDITIONS OBSERVATIONS

Run Numbers 6 through 12 were made with the following experimental conditions: No. 4A Coal 25 grams, -100+200 mesh, coal/solvent weight ratio 1:4, reaction time 20 mins at 350°C.

6 11/11/79 Filtration on W541 paper placed on Initially, 8-10 CC of filtrate a heated buchner funnel. resulted and then it stopped. It seems that No. 4A coal reacts better than No. 8 Coal.

7 11/29/79 Filtration of W54l placed on a heated Filter aid plugged the filter paper-­ buchner funnel with the addition of filter no filtrate. Also the addition of aid (celite 545) to the coal-solvent filter aid caused the coal-solvent slurry at the time of filtration. slurry temperature to go down and its viscosity to go higher, which made filtration task more difficult.

8 12/3/79 Filtration with a dispersion tube fitted Vacuum line was plugged due to the cylinder type, immersed into the coal condensation of phenathrene vapor solvent slurry at the time of filtration. - as a result filtration stopped. Slurry was taken out with the help of aspirator vacuum.

9 12/7/79 Filtration method same as in Run Number 8. Vapor line was plugged due to the condensation of phenanthrene vapor. TABLE16 (Cont'd)

PREPARATIONOF LOWASH COALUSING PHENANTHRENE

RUN NUMBER DATE DESCRIPTIONS OF CONDITIONS OBSERVATIONS

10 12/13/79 Filtration method same as in Run Number 8. Initially, small filtrate resulted. Filtrate line was then plugged due to the condensation of phenathrene vapor. Filtrate had ash content of 1.2% by weight (by ASTMmethod D271-68.

11 12/25/79 Filtration with the dispersion tube and 2 Filtration rate was good. Experi­ psia N2 pressure applied at the time of ment was terminated due to filtration. leakage on the filtrate line.

12 1/5/80 Filtration method same as in Run Number 11. Filtration rate was good. There was no problem in filtration. After removing phenathanthrene from filtrate, Low-ash product was about 2 grams. Yield of the product 8%.

13 1/9/80 Repetition of all the conditions of Run Filtration rate was good. After remov­ Number 11, except coal/solvent weight ing phenanthrene from the filtrate, ratio was 1.6. resultant low-ash product was only a fraction of a gram. 125

Run No. 6 through 13 (Table 16) indicate the efforts that were made for the filtration of coal-solvent slurry. The filtration problem was finally solved by using the dispersion tube (Fisher type coarse, pyrex #11-138B). The dispersion tube was immersed into a hot coal-solvent slurry at the time of filtration. After making the proper seals the slurry was forced through the dispersion tube by means of a 2 psig N pressure. The filtration step was carried out 2 as quickly as possible, so as not to allow the slurry temperature to go down. The slurry viscosity increased rapidly with a decrease in

temperature which could result into filtration difficulties.

After the filtration step the collected filterate was then washed with warm toluene to remove phenanthrene. The yield of the low ash product was about 2 grams out of 25 grams of No. 4A coal. (Run No.

12). The same experimental conditions were repeated using an

increased quantity of coal (Run No. 13). The yield of low-ash product in this case was found to be only a fraction of a gram. All

of the filterate that was collected was only phenanthrene with very

small amounts of dissolved coal in it.

The expermental findings here suggest that phenanthrene can not

be used to dissolve two types of Ohio coals, namely Ohio No. 4A and

No. 8 Coal. A previous report (37) indicated a yield of low-ash

product of high as 56% using phenanthrene, which was never obtained

here. The maximum yield of the product was around 7-8% by weight.

Due to this, a fresh different procedure was used to obtain low-ash

coal which is described below. 126

In this part of the investigation a mixture of solvents with the composition 3 parts by weight of l-methyl naphthalene and 1 part by weight of tetra1ine was used for the dissolution of No. 4A coal. The dissolver used was a one liter stainless steel autoclave (Autoclave

Engineers, Erie, PA). The procedure that was used is described in the previous chapter. Table 17 summarizes the results of the experimental runs that were made.

In the present method the coal-solvent slurry was collected in boiling p-cresol. The ratio of slurry to cresol was about 1:5 by weight. The cresol used here acted as a diluent and helped in the filtration of the coal-solvent slurry. The cresol from the resultant filtrate was then separated by the vacuum distillation. Run Nos. 17,

18, and 19 were made at the same conditions of Run No. 16 to get sufficient quantity of low-ash coal so that it could be ground and mixed with No. 6 oil for the stability study.

In the final stage, vacuum distillation was carried out to remove cresol from the coal-solvent slurry. In this distillation process boiling chips· were added to avoid bumping of the coal-slurry. This was a mistake and it should have been avoided because boiling chips contributed the ash to the final product. The ash-analysis of the final product indicated ash content of 3-4% by weight (see Table 17) out of which 1 to 2% should have been contributed by the boiling chips. Table 17 also shows that sulfur content of No. 4A coal was reduced from 3-4% by weight down to 1-1/2% by weight. (See results of Run 17, 18 and 19). 127

TABLE 17

PREPARATION OF LOW-ASH COAL

RUN DATE OBSERVATIONS AND RESULTS NUMBER

16* 2/8/80 Filtration rate was good. Ash content** in residue was 24.61% by weight.

17 2/29/80 Filtration rate was good and it was inc~ased if the cresol-coal slurry was heated prior to the filtration.

Amount filtrate collected was about 1 liter (in 2 hrs. of time).

Weight of Low-ash product (after distilling off the cresol & other solvents) was found to be 44 grams while that of residue (on the filter paper) was found to be 30 grams. Product yield 44%.

Weight percent ash: 5.86% in product and 34.5% in residue. Weight percent sulfur: 1.64% in product and 3.22% in residue.

18 3/9/80 Filtration rate was good. Amount of filtrate collected about 1 liter. Weight of Low-ash product 48 grams i.e. 48% product yield while that of residue was 30 grams.

Weight percent ash: 5.96 in product and 36% in residue. Weight percent sulfur: 1.54% in product and 3.66% in residue.

19 3/10/80 Weight of Low-ash product 52 grams i.e. 52% product yield while that of residue was 31 grams.

Weight percent ash: 2.91% in product and 40% in residue. Weight percent sulfur: 1.37% in product and 4.13% in residue

* Run number 16 through 19 were made with the following experimental conditions: 128

TABLE 17 (Cont.)

PREPARATION OF LOW-ASH COAL

1. Ohio No. 8 coal, particle size -200+325 mesh.

2. Use of mixture of solvents i.e. 3 parts by weight I-methyl naphthalene and 1 part by weight tetraline, with coal/solvent weight ratio of 1:4.

3. Reaction time of 20 minutes at about 750°C temperature in autoclave.

4. Coal-solvent slurry diluted with p-cresol (about 3 parts cresol 1 part slurry) and heated up the boiling before filtration.

5. Filtration on W-54l filter paper placed on Buchner funnel.

** Ash and sulfur content determination by ASTM D271-68 method at Chemistry Laboratory, Ohio University. 129

In general this procedure used was a success. A considerable amount of coal went into the solution producing a good quality low-ash coal. The maximum yield of low-ash coal was around 52%, reducing the ash content from about 14% by weight (for No. 4A coal) down to 2-3% by weight. CONCLUSIONS

1. Solid Solvent Refined Coal/No. 6 fuel-oil mixtures were found to

be more stable than Ohio No. 8 Coal/No. 6 fuel-oil mixtures of

equivalent compositions.

2. Stability of the coal-oil mixtures increased with an increase in

coal particle finess and decreased with an increase in the

mixture's temperature.

3. The pendulum apparatus can be used to compare the settling

stability of various coal-oil mixtures, by comparing their e.G.

drop values.

4. The correlation developed between the C.G. drop and the variation

in weight percent coal along the coal-oil mixture column length

can be used for the coal concentration predictions. Here the

coal particle size distribution play an important role and size

distribution should be as narrow as possible.

5. The exact behavior of coal particles in oil can not be predicted

without microscopic observations. Since No. 6 oil used was very

dark in color any indirect methods (based on light as a source)

were found to be unsuccessful.

6. Viscosity of coal-oil mixtures were found to rise markedly in the

region of 40 percent and higher coal content by weight. This

rise was higher for SRC/oil mixture than No. 8/oi1 mixture. 131

Also, the viscosity of coal-oil mixtures were found to dec rease

rapidly with an increase in the mixture's temperature (from 25°C

to 60°C) and a decrease in the coal particle fineness.

7. The coal-oil mixtures were found to be thixotropic in nature,

particularly above 40% coal by weight. The amount of thixotrophy

was found to be higher for 50% SOM than for 50% COM.

B. Density of coal-oil mixtures showed an expected change with

temperature. The decrease in density value with an increase In

temperature was just a few percentage.

9. Phenanthrene was found to dissolve only a small percentage of

Ohio No. 8 and No. 4A coals. The yield of the product was very

low, as a result phenanthrene can not be used to produce low-ash

coal.

10. A mixture of solvents consisting of l-methyl-naphthalene and

tetralin followed by p-cresol as a filtration aid for the

coal-solvent slurry can be used to produce a sizable amount and

good quality of low-ash coal.

11. The coal-liquefaction methods used here reduced the ash content

of the No. 4A coal from 14% down to 2-3% by weight and sulfur

content from 4% down to 1-1/2% by weight. The average yield of

the low-ash product was 50 percent by weight. RECOMMENDATIONS

1. The pendulum's best position for the axis of support should be

determined experimentally, as it was done here. The setting used

should be such that it can reproduce the e.G. drop values

accurately enough to detect any settling of coal particles in the

oil.

2. For better accuracy of the pendulum's period measurement a

crystal controlled timer should be used.

3. For the study of the variations in coal concentration along the

column length, a series of ball valves were attached together.

With this arrangement the sample points were at least at 6"

distance apart. However for a better picture of the variation in

coal concentration, particularly, for the top 6" section, samples

should be taken at every I" distance. The reason being that an

interface 2.!. abrupt change in coal concentration is expected in

that section of the column.

4. The metal detector used for the stability study was not accurate

enough to detect settling of coal particles. It is recommended

to improve the circuit before further use.

5. The thixotropic behavior of coal-oil mixtures should be further

investigated. The relationship between the mixture's viscosity 133

and its age should be further studied by varying the coal

particle size and the mixture temperature. It is also

recommended that a high shear rate should be employed in

viscosity determinations to show the rheological properties of

the fluid under a actual pumping condition.

6. The coal liquefaction procedure using an autoclave should be

further investigated using other types of Ohio coals. The

resultant solvent refined products should be tested in detail so

as to know what types of coal components are dissolving. REFERENCES

1. Morris, S. C., Moskowitz, P. D., Sevian, M. A., Silberstein, S.,

Hamilton, L.D. , "Coal Conversion Technologies: Some Health and

Environmental Effects," Science, Vol. 206, P. 654-662,

November 1979.

2. Crynes, B. L., "Chemical Reactions As a Means of Separation ­

Sulfur Removal," Marcel Dekker, Lnc ., New York 1977.

3. "Coal Conversion and Utilization, " Energy Research and

Development Administration, Washington D.C., 1975 Technical

Report, ERDA 76-86.

4. "Solvent Refined Coal (SRC) Process, Operation of Solvent Refined

Coal Pilot Plant at Wilsonville, Alabama," Annual Report,

January-December 1976, EPRI AF-585, November 1977.

5. Jackson, D. M., and Schmid, B. K., "Commercial Scale Development

of the SRC-II Process," a paper presented at Fifth Annual

International Conference, University of Pittsburgh, PA.,

August 1-3, 1978.

6. Second International Symposium on Coal-Oil Mixture Combustion,

Vol. I and II, November 27-29, 1979, Denver, Massachusets, ed.,

Mitre Corp, McLean, VA., 1979.

7. Foster, E. P., Gupta, A. S., Dooher, J. P., Kelly, C. M., 135

"Rheological Properties of Solvent Refined Coal-Oil Mixtures,"

Adelphi Research Center, Adelphi University, N.Y., 1979.

8. Barkley, J. F. Hersberger, A. B., and Burdick, L. R., "Laboratory

and Field Tests on Coal-in-Oil Fuels," American Society of

Mechanical Engineers, Transactions, Vol. 66, 1944, page 185-198.

9. Final Report of the General Motors Corporation Powdered Coal-Oil

Mixtures (COM) Program, March 1975 - July 1977, ed , A. Brown,

Jr., Report For U.S. Department of Energy, contract

No. EX-76-C-Ol-2267.

10. Viola, M.A., Botsaris, G.D.," Coal-Oil Mixtures: Their Technical

and Commercial Status," Tufts University, Medford, Massachusetts,

U.S.A.

11. Viola, M. A., Botsaris, G. D., Glazman, Y. M., "An Investigation

of the Hydrophi1ic/Oleophilic Nature of Various Coals: its

Importance to the Stability and Rheological Properties of

Coal-Oil Mixtures," paper presented at the Symposium on Colloid

and Interfacial problems in Coal Utilization, l79th National

Meeting of the American Chemical Society in Houston,

March 27, 1980.

12. Gradisar, F. J., Faith, W. L., and Hedrick, J. E., "Laminar Flow

of Coal-Oil Suspensions," Transactions American Institute of

Chemical Engineers, Vol. 39, April 25, 1943, page 201-222.

13. Coburn T. T., "Evaluation of 'Stable' Emulsions of Coal," paper

presented at Second International Symposium on Coal-oil Mixture

Combustion, Vol. III, ed. Mitre Corp., MClean VA. 1979 136

14. Dooher, J. P., Coal Desulfurization During the combustion of

coal/oil/water Emulsions: An Economic Alternative Clean Liquid

Fuel," Interim Report for the period October 1978 - April 1979,

Adephi University, May, 1979.

15. McMillen, J. H., Stutzman, L. F., and Hedrick, J. E., "APendulum

Method for Measuring Settling Velocities," Industrial and

Engineering Chemistry, Analytical Edition, Vol. 13, 1941, page

475-478.

16. "The use of Additives to Stabilize Coal-Oil Mixture," paper

presented at Second International Symposium on COM combustion,

November 27-29, Denver, Massachusets, by Akihiora Naka, Dai '­

Ich! Kogyo Seiyaku Co., Ltd., Japan.

17. "COM Stability forecasting Method," paper presented at Second

International Symposium on COM combustion, November 27-29, 1979,

Denver, Massachusets, by Yoshikazu Ojura, Neos Co., Ltd., Japan.

18. Lowry, H. H. and Rose, H. J.," Pott-Broche Extraction process and

plant of Ruhro1 G.m.b.H., Bottrop-Welheim, Germany," U.S.

Department of the Interior Bureau of Mines, Information

Circular, I.C. 7420, October 1947.

19. Symposium on Coal Liquefaction, preprints, Div. Fuel Chemistry,

American Chemical Society, 1976, Vol. 21, No.5.

20. Benjamin, B. M., et.a1., "Thermal Cleavage of Chemical bonds in

selected Coal-Related Structures," Fuel, Vol. 57, page 269-272,

May, 1978.

21. Neavel, R. C., "Liquefaction of Coal in Hydrogen-donor and 137

non-donor vehicles," Fuel, Vol. 55, page 237-242, July, 1976.22.

Curran, G. P., Struck, R. T., and Gorin, E., "Mechanism of the

Hydrogen Transfer Process to Coal and Coal Extracts," I&EC,

Process Design and Development, Vol. 6, page 166, 1967.

23. Guin, J. M., Tarrer, A. R., Taylor, Z. L., Jr., Green, S. C.,

"Mechanistic Study of Coal Dissolution," I&EC, Process Design and

Development, Vol. 15, No.4, page 490-494, 1976.

24. liebler, M. W., "The Chemistry of Coal Utilization," Vol. I, page

715, John Wiley and Sons, New York, 1945.

25. Dryden, I. C. G. "Behavior of Bituminous Coal Toward Solvents I,"

Fuel, Vol. 29, page 197, 1950.

26. Dryden, I. G. C., "Behavior of Bituminous Coal Toward Solvents

II," Fuel, Vol. 29, page 221, 1950.

27. Stopes, M. C., Proc. Roy. Soc. (London), B-90, 1919. From: Ref.

No. 28.

28. Charlot, L. A., "The Kinetics of Thermal Dissolution of a Utah

Bituminous Coal using 1, 2, 3, 4 Tetrahydronaphthalene," M. S.

Thesis, Department of Fuel Engineering, University of Utah,

August, 1973.

29. Kreulen, D. J. W., "Elements of Coal Chemistry," Rotterdam, page

170, 1948.

30. Oele, A. P., et.a1., "Extractive Disintegration of Bituminous

Coals," Fuel, Vol. 30, page 169, 1951

31. Golumbic, C., e t , a1., "Solvent Extraction of Coal by Aromatic

Compounds at Atmospheric Pressure," Bureau of Mines, Report of

Investigation, 4662, 1950. 138

32. Gillet, A. "Action of Solvents on Coal," Chem, Age (London), 65,

page 147, 1951.

33. Hill, G. R. and lyon, L. B., "A New Chemical Structure for Coal,"

Ind. and Eng. Chem., Vol. 54, p. 36, 1962.

34. Asbury, R. S., "Action of Solvents on Coal," Ind. Eng. Chem, ,

Vol. 26, p. 1201, 1934.

35. Crick, R. G. D., "Solvent Extraction of Lignites and Bituminous

Coals," Fuel, 30, p. 187, 1951.

36. Kloepper, D. L., e t , a1., "Solvent Processing of Coal to produce

a De-ashed Product," R&D Report No.9, Spencer Chemical Division,

prepared for Office of Coal Research, U.S. Department of

Interior, 1965.

37. "Exploratory Research on preparation of Low-ash coal by Solvent

Extraction," Bituminous Coal Research, Lnc ,, Progress Report No.

land 2, for North American Coal Corporation, January

September 1959.

38. Rose, H. J. and Hill, W. H., "Coal Treatment Process," United

States Patent No.1, 925, 005, August 29, 1933.

39. Orchin, M., Golumbic, G., Anderson, J. E. and Stroch, H. H.,

"Extraction of Coal with Phenanthrene," u.s. Bureau of Mines,

Bull. 505, 1951.

40. Heredy, L. A. and Fugassi, P., "Phenanthrene Extraction of

Bituminous Coal", Advances Chem. Ser., No. 55, p. 448-459, 1966.

41. Maddocks, R. R., "Advances in SRC Technology," paper presented at

American Chemical Society, Miami, Florida, September, 1978. 139

42. Private communications with Mr. R. C. Tailor, Graduate Research

Associate at the Accelerator Lab., Dept. of Physics, Ohio

University, Athens, Ohio.

43. Private communications with Dr. James Tong, Professor of

Chemistry, Ohio University, Athens, Ohio.

44. Private communications with Mr. A. Swearingen, INT Technician,

Ohio University, Athens, Ohio.

45. "Industrial Rheology and Rheological Structures," by Late H.

Green, John Wiley and Sons, Inc. 1949.

46. Telephone conversations of Dr. R. L. Savage with Mrs. Cooper at

Southern Services Inc., dated January 29, 1980.

47. Irani, Riyad R., particle size: measurement, interpretation, and

application, New York, Wiley, 1963.

48. Studies on the Stabilization of COM, a paper presented at the

second International Symposium on COM Combustion,

November 27-29, 1979, Denver, Massachusets, by M. Yamamura,

T. Yamashita, T. Igarashi, Japan. APPENDIX A A-2

Derivation of the formula used for the pendulum:

Period T of a compound pendulum can be expressed as

4 rrZ I (1) = Mgr where I is the moment of inertia of the pendulum about the axis of support, M is the mass of the pendulum, g is the acceleration due to gravity and r is the radius of the center of gravity.

In the present investigation, the period of the pendulum was measured first with the tube in its normal position inside the earriage, designated as Tl' and then wi th the tube raised through a known distance referred to its support by insertion of a block of known dimensions, designated as TZ. Corresponding equations for the periods TI and TZ can be written as

Z 4 1f ZI 1 + 4 1f2 Ie TI (2) Meg ~ + Mtg rt

2 41\2 1Z + 47fZ Ie + 4 rr 2 Ib TZ (3) Meg re + Mt g (rt -d) + Mb g rt The various terms used in equation 2 and 3 are:

TI period of compound pendulum without block, sec. TZ period of compound pendulum with block inserted, sec. Me mass of carriage, gram rc radius of center of gravity of carriage, cm ~ mass of tube and its contained suspension, gram r t radius of center of gravity of tube and its contained suspension in its initial position i.e. without block inserted, cm d distance through which tube is raised, cm Mb = mass of inserted block, gram. rb = radius of center of gravity of inserted block, cm g acceleration due to gravity, cm/sec2 II = moment of inertia of tube and its contained suspension in its initial position about axis of support, gram/cm2 12 moment of inertia of tube and its contained suspension (block inserted position) about axis of support, gram/cm2 A-3

moment of inertia of inserted block about axis of support, gram/cm2 moment of inertia of carriage about axis of support, gram/cm2

It is difficult to calculate the value of I c and it can be elimi- nated with the help of equation 2 and 3. By rearranging equation 2 and 3, 2 2 47f2I l + 4 7f2 I c = TI Mc g r c + TI Mtg rt (2' )

2 2 T2 Mt g rt - T2 [X] (3' ) where,

subtracting equation 2' from equation 3'

2 2 (T2 - TI )Mt g rt

- T2 2 [X] - Tl 2 Mc g r c (4)

Now the relationship between 11 and 12 can be established by the theorem of mechanics relating the moment of inertia 1 about any axis to the moment of inertia 10 about an axis through the center of gravity (e.G.). 2 1 = 10 + m r (5) with the help of equation 5,11, 12 and 10 can be written as,

(6)

lOt + Mt (rt -d)2 (7)

lOb +Mb rb 2 (8) where,

lOt moment of inertia of tube and its contained suspension about an axis passing through its C.G.

lOb moment of inertia of inserted block about an axis passing through its C.G. and can be calculated as lOb 2 ~ 1/6 Mb(d + t 2 ) where d is the height and is the length of inserted block and Mb is the mass.

subtracting equation 6 from 7

(9) A-4 substituting the value of '12 - II' from equation 9 in equation 4 and rearranging for the term rt, the resultant equation is

2 222 2 TI Me g r e + [Mtgd-(Megre+Mbgrb) ]12 + 4 IT Mtd + 41f Ib

Mt g ( T2 2-TI 2) + 87f2Mtd (10) With the pendulum used the values for various terms in equation 10 were as follows:

Mb = 2.4266 grams, rb=22.24 em, d=1.32 em and 1=1.9 em, 4 n2Ib=4.7469 x 104 gram/em2

Me 70.9248 grams, r e=5.6 em

g 981 em/sec2

TI' T2 = Time periods measured, sec.

Mt = Mass of tube and its contained suspension, varied from tube to tube and are given in Table A-I below for all the tube used.

Table A-I

Test Tube Mass of Tube and its Number Designation Contained Suspension, gram. Mt

1 PI 272.7 2 P2 271.0 3 P3 270.7 4 P8 273.1 5 P4 265.6 6 P6 267.0 7 P7 268.5 8 PIO 265.4 9 P12 246.0 10 Poil 249.8 APPENDIX B B-2.

Procedure Used For The Percent Solids Determination in Coal-Oil Mixtures:

The following procedure was used for the percent solids determination for No. 8 coal/No. 6 fuel coil mixtures. The procedure is designated as 'KVS Method' and is based upon the letter from Kennedy Van Saun Corporation to Dr. R. L. Savage, dated April 2, 1980.

1. Take a 1 to 1-1/2 gram sample of coal-oil mixture.

2. Dilute sample with 100 to 150 ml of toluene.

3. Mix and heat sample to 150°F (maximum).

4. Weigh Whatman 541 filter paper.

5. Filter the diluted coal-oil muxture (containing toluene) on W 541 filter paper. Use an aspirator (filter pump) if required.

6. Use additional toluene to wash off any yellowish tint left on the filter paper.

7. Oven dry filter paper (containing coal particles) at 200 to 212°F.

8. Weigh the filter paper again.

NOTE: For the mixture of solid SRC/No. 6 fuel oil, the same procedure was used but instead of toluene at 150°F a milder solvent, kerosene, at room temperature was used. Kerosene was found to be satisfactory for the solid SRC/No. 6 fuel oil mixtures for the percent solids determinations. APPENDIX C C-2.

Proximate, Ultimate, Sulfur and Ash Analysis For The Coal Used*

I Proximate (%) Ultimate (%) ~orms of Sulfur

~ oi( ~ H (1) Q) .c ~ +J ~ ..., E co 0 ==' Z ~ ,.0 ~ (1) H r-1 Pot (1) Q) Q) m ~ ~ ;j ~ r-1 H M U Q) (1) U) Q) CJ CJ E-t .r-f ;j -r1 0.0 s: 00 s:: +oJ .r-f -rot ~ +J +J ~ ...,0 0 0 CJ) r-1 co +J r-I CJ) Cd Q) ..c ~ 00 co ~ -M a m Cf.) eM M ~ ,.c "tj ~ +J +oJ r-1 ~ 00 0 C.!> 0 0 eM (J) ~ eu -r-l ~ 0 =' ~ ~ U 0 ):: :> ~ -< ~ U Z 0 E-t Cf.) Pol 0

Ohio Number 8 732X 2.0 40.9 46.1 11.0 5.3 70.1 1.2 7.5 4.9 0.21 3.43 1.24

Clarion, Ohio Number 4A 805X 4.2 34.9 43.8 17.1 5.2 61.1 0.9 12.7 3.0 0.16 1.09 1.73

* Analysis are based upon the report provided by Dr. William Kneller at the University of Toledo under the joint research on "A Study of Potential Use of SRC in Ohio" sponsored by The Ohio Air Quality Development Authority.

** OGS (Ohio Geological Survey) number refers to the number given in the above mentioned report. APPE~TJ)IX D D-2

SETTLING DATA FOR TEST NO. 1 (TUBE PI)

DAY DROP IN OF TIME PERIOD, T2 TIME PERIOD, TI VALUE OF rt* C.G. TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS MM

0 2323 -+ 2.8 1685 -+ 1.3 11.30 0.00 1/2 2267 -+ 2.5 1662 -+ 1.3 11.94 0.64 1 2253 -+ 3.6 1658 -+ 1.4 12.05 0.75 (2256 -+ 2.6)** (1654 -+ 1.9) 6 2167 -+ 1.4 1624 -+ 1.3 13.88 2.08 7 2147 -+ 2.9 1618 -+ 1.3 13.60 2.30 14 2108 -+ 1.1 1599 + 0.8 14.27 2.97 24 2067 + 1.5 1580 -+ 1.1 14.80 3.50 (2070 -+ 1.9) (1580 -+ 0.3) 32 2036 + 2.9 1567 + 1.3 15.42 4.12

* rt is the radius of center of gravity of tube and its contained suspension, calculated by the formula given in Appendix A.

** Values in parenthesis indicate the reproducibility in period measurement, where the periods were measured by fixing the settling tube again inside the carriage.

NOTE: Time period values shown are the average for 10 measurements taken at a time. + values indicate the deviation. D-3

SETTLING DATA FOR TEST NO. 2 (TUBE P2)

DAY DROP IN OF TIME PERIOD, T2 TIME PERIOD, TI VALUE OF rt* e.G. TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS MM

0 2474 -+ 2.5 1744 -+ 1.4 8.53 0.00 1/4 2426 -+ 2.4 1724 -+ 1.5 8.91 0.38 1 2285 -+ 2 1668 -+ 1.2 10.32 1.79 2 2219 -+ 3.7 1638 -+ 1.2 11.02 2.67 8 2127 -+ 2.2 1602 -+ 1.6 12.30 3.77 12 2115 -+ 4.1 1603 -+ 2.4 12.72 4.19 16 2107 -+ 2 1594 -+ 0.7 12.61 4.08 32 2097 -+ 2.4 1590 -+ 1.2 12.86 4.33 48 2066 -+ 2 1577 -+ 0.8 13.30 4.77 D-4

SETTLING DATA FOR TEST NO. 3 (TUBE P3)

DAY DROP IN OF TIME PERIOD, T2 TIME PERIOD, Tl VALUE OF rt* e.G. TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS MM

0 2252 -+ 3.6 1746 -+ 1.65 8.60 0.00 1/2 2438 -+ 4.1 1747 -+ 1.4 8.87 0.30 2 2412 -+ 3.3 1737 -+ 1.5 9.16 0.56 3 2393 -+ 2.1 1726 -+ 1.5 9.25 0.65 8 2347 -+ 2.4 1705 -+ 1.4 9.61 1.01 12 2317 -+ 2.1 1690 -+ 1.8 9.86 1.26 16 2306 + 2.3 1688 + 0.7 10.14 1.54 (2300 + 2) (1689 + 0.8)

24 2557 -+ 2.9 1660 -+ 1 10.34 1.74 D-5

SETTLING DATA FOR TEST NO. 4 (TUBE P8)

DAY DROP IN OF TIME PERIOD, T2 TIME PERIOD, TI VALUE OF rt* C.G. TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS MM

0 2460 -+ 2.5 1734 -+ 1.7 8.47 0.00 4 2398 3.6 1708 1.5 8.98 0.51 -+ -+ 6 2389 -+ 2.7 1705 -+ 2.2 9.07 0.60 8 2377 -+ 2.7 1699 -+ 1.8 9.14 0.67 12 2324 -+ 3.2 1674 -+ 1 9.54 1.07 16 2328 -+ 2 1682 -+ 0.6 9.72 1.25 20 2246 -+ 3.5 1645 -+ 1.6 10.47 2.00 D-6

SETTLING DATA FOR TEST NO. 5 (TUBE P4)

DAY DROP IN OF TIME PERIOD, T2 TIME PERIOD, T1 VALUE OF rt* e.G. TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS MM

0 2528 -+ 6.4 1739 -+ 1.4 9.54 0.00 1 2547 -+ 4.5 1742 -+ 2.8 9.31 -0.23 2 2570 -+ 3.1 1753 -+ 1.9 9.19 -0.35 12 2545 -+ 4.4 1744 -+ 1.5 9.40 -0.14 24 2496 -+ 2.3 1732 -+ 1.5 9.93 0.39 32 2465 -+ 3.3 1726 -+ 1.4 10.36 0.82 40 2434 -+ 3.6 1708 -+ 1.1 10.47 0.93 D-7

SETTLING DATA FOR TEST NO. 6 (TUBE P6)

DAY DROP IN OF TIME PERIOD, T2 TIME PERIOD, Tl VALUE OF rt* e.G. TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS MM

0 2502 -+ 2.6 1763 -+ 0.9 7.87 0.00 4 2463 -+ 2.3 1752 -+ 1.3 8.31 0.44 9 2414 -+ 2.9 1728 -+ 1.5 8.62 0.75 16 2412 -+ 3 1731 -+ 1.8 8.72 0.85 24 2377 -+ 3.5 1717 -+ 1.3 9.09 1.22 32 2333 -+ 4.4 1702 -+ 1.8 9.64 1.77 D-8

SETTLING DATA FOR TEST NO. 7 (TUBE P7)

DAY DROP IN OF TI:ME PERIOD, T2 TIME PERIOD, Tl VALUE OF rt* C.G. TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS MM

0 2491 -+ 1.2 1722 -+ 1.3 9.03 0.00 1 2507 -+ 2.5 1723 -+ 1.7 8.79 -0.24 2 2540 -+ 4.7 1720 -+ 2.7 8.21 -0.82 4 2534 -+ 5.8 1728 -+ 1.3 8.46 -0.57 9 2459 -+ 2.7 1716 -+ 1.5 9.46 0.43 12 2436 -+ 3.6 1692 -+ 2 9.28 0.25 16 2455 -+ 3.7 1707 -+ 1.1 9.31 0.28 24 2387 -+ 2.5 1682 -+ 1.5 9.93 0.90 32 2335 -+ 3.9 1662 -+ 1.1 10.45 1.42 40 2259 -+ 4.2 1652 -+ 1.2 11.93 2.9 D-9

SETTLING DATA FOR TEST NO. 8 (TUBE P8)

DAY DROP IN OF TIME PERIOD, T2 TIME PERIOD, TI VALUE OF rt* e.G. TEST IN MILLISECONDS IN MILLISECONDS IN MILLIMETERS MM

0 2565 -+ 2.9 1787 -+ 1.6 7.24 0.00 4 2540 -+ 3.4 1780 -+ 1.5 7.51 0.27 8 2531 -+ 3 1777 -+ 1.4 7.58 0.34 16 2472 -+ 4.2 1754 -+ 1.6 8.08 0.84 8.16 0.92 24 2479 -+ 2 1762 -+ 1.5 32 2474 -+ 6 1755 -+ 1.4 8.07 0.83 60 2408 -+ 3 1716 -+ 1.6 8.29 1.04 APPENDIX E E-2

DATA FOR A METAL DETECTOR

40% COM AT 25°C, AFTER 1 HOUR

LIQUID LEVEL OF ABOUT 1" ABOVE THE FIRST COIL CHART SPEED 50 IN/MIN

TURN TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN NUMBER EACH SUCCESSIVE COIL. (FROM STD TOP) 1* 2 3 4 5 MEAN DEVIATION

1 614 633 567 567 638 613 49 2 968 968 954 874 902 933 43 3 1063 1039 1030 986 997 1023 31 4 1110 1087 1039 1016 1016 1054 43 5 1134 1129 1039 992 1039 1067 62 6 1134 1134 1096 1082 1096 1108 24 7 1134 1228 1134 1087 1115 1140 53 8 1181 1370 1181 1134 1205 1214 91 9 1252 1559 1181 1134 1181 1261 172 10 1252 1771 1228 1181 1190 1324 251 11 1323 1748 1252 1228 1205 1351 226 12 1370 1710 1275 1205 1304 1373 197 13 1512 1748 1238 1228 1233 1394 231 14 1635 1757 1323 1275 1238 1445 234 15 1753 1767 1323 1323 1512 1535 219 16

* Experiment repeated five times using the same weight and diameter (ball bearings 1/8" dia.) spheres. E-3

DATA FOR A METAL DETECTOR

40% COM AT 25°C, AFTER 8 HOURS

LIQUID LEVEL OF ABOUT 1" ABOVE THE FIRST COIL

TURN TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN NUMBER EACH SUCCESSIVE COIL. (FROM STn TOP) 1* 2 3 4 5 MEAN DEVIATION

1 685 709 614 614 661 657 42 2 1044 1063 1016 1039 1016 1036 20 3 1205 1181 1096 1334 1157 1195 88 4 1181 1228 1195 1338 1271 1243 64 5 1260 1266 1266 1205 1323 1264 42 6 1228 1299 1285 1266 1512 1318 111 7 1260 1322 1323 1275 1672 1370 171 8 1346 1370 1416 1329 1899 1472 241 9 1346 1417 1394 1327 2055 1508 308 10 1323 1417 1346 1323 2230 1528 394 11 1346 1417 1379 1370 2386 1580 451 12 1346 1319 1285 1417 2338 1541 448 13 1332 1375 ** 1512 2277 1624 442 14 1332 1375 ** 1738 2315 1690 455 15 1559 1559 16 ** ** ** **

* Experiment repeated five times using the same weight and diameter (ball bearings 1/8" dLa, ) spheres.

** Can not be determined from XY recorder graph. E-4

DATA FOR A METAL DETECTOR

40% COM AT 25°C, AFTER 2 DAYS

LIQUID LEVEL OF ABOUT 1" ABOVE THE FIRST COIL

TURN NUMBER TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN (FROM EACH SUCCESSIVE COIL. TOP) 1* 2 3

1 ** 708 331 2 2291 1417 732 3 2504 1653 1464 4 2421 2102 1795 5 2598 2008 2079 6 3012 2362 2183 7 2964 2551 2055 8 3165 2835 2662 9 3189 3047 2608 10 3661 3153 2409 11 ** 3708 2551 12 ** 3661 2835 13 ** 4193 2995 14 ** ** 3354 15 ** ** ** 16

* Experiement repeated three times using the same weight and diameter (1/8" ball bearings) spheres.

** Can not be determined from XY recorder graph. E-5

DATA FOR A METAL DETECTOR

GLYCERINE SOLUTION AT 25°C LIQUID LEVEL OF ABOUT 1" ABOVE THE FIRST COIL CHART SPEED 20 IN/MIN

TURN TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN NUMBER EACH SUCCESSIVE COIL. (FROr-l STD TOP) 1* 2 3 4 5 MEAN DEVIATION

1 472 472 484 413 460 460 27 2 590 531 578 578 566 569 23 3 590 590 590 590 590 590 0 4 590 590 602 590 590 592 5 5 590 590 637 590 590 599 21 6 590 614 602 625 625 611 15 7 649 614 614 625 625 625 14 8 649 661 685 685 649 666 18 9 649 649 696 685 696 675 24 10 673 673 649 649 625 654 20 11 696 685 696 696 696 694 5 12 649 685 685 661 625 661 25 13 649 631 657 696 708 665 34 14 649 708 696 696 649 680 28 15 614 649 649 649 649 642 15 16

* Experiment repeated five times using the same weight and diameter (1/8 inch ball bearings) spheres. E-6

DATA FOR A METAL DETECTOR

GLYCERINE SOLUTION AT 25°C LIQUID LEVEL OF ABOUT I" ABOVE THE FIRST COIL CHART SPEED 50 IN/MIN

TURN TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN NUMBER EACH SUCCESSIVE COIL. (FROM STD TOP) 1* 2 3 4 5 MEAN DEVIATION

1 462 514 373 415 481 449 55 2 557 543 543 514 543 540 15 3 566 604 566 543 566 569 22 4 581 566 590 543 590 574 20 5 590 609 604 571 609 597 16 6 614 614 604 623 623 615 8 7 633 628 628 614 623 625 7 8 661 656 651 651 656 655 4 9 666 661 666 656 656 660 6 10 656 661 661 656 661 659 3 11 685 666 670 656 661 667 11 12 651 661 637 656 637 648 11 13 656 637 661 637 661 650 12 14 685 661 651 661 661 664 13 15 614 618 618 623 637 622 9 16

* Experiment repeated five times using the same weight and diameter (1/8 inch ball bearings) spheres. E-7

DATA FOR A METAL DETECTOR

GLYCERINE SOLUTION AT 25°C LIQUID LEVEL OF ABOUT 4" ABOVE THE FIRST COIL CHART SPEED 20 IN/MIN

TURN TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN NUMBER EACH SUCCESSIVE COIL. (FROM STn TOP) 1* 2 3 4 5 MEAN DEVIATION

1 732 768 744 756 732 764 15 2 803 756 780 803 803 789 21 3 803 768 827 815 803 803 22 4 803 803 827 768 791 791 21 5 803 803 827 815 803 810 10 6 827 827 886 839 839 843 24 7 827 803 850 827 827 829 16 8 815 850 839 839 815 832 16 9 839 827 839 827 839 834 6 10 827 815 839 839 827 829 10 11 827 850 862 827 827 839 16 12 827 827 815 839 839 829 10 13 815 768 827 815 768 813 27 14 827 827 850 839 827 834 10 15 803 803 780 815 780 796 15 16

* Experiment repeated five times using the same weight and diameter (1/8" ball bearings) spheres. E-8

DATA FOR A METAL DETECTOR

GLYCERINE SOLUTION AT 25°C LIQUID LEVEL OF ABOUT 4" ABOVE THE FIRST COIL CHART SPEED 50 IN/MIN

TURN TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN NUMBER EACH SUCCESSIVE COIL. (FROM STn TOP) 1* 2 3 4 5 MEAN DEVIATION

1 756 780 732 746 761 755 18 2 780 794 803 808 813 800 13 3 780 794 803 803 794 795 9 4 808 836 808 803 789 809 17 5 808 794 808 808 813 806 7 6 813 850 850 827 817 831 17 7 841 822 841 855 846 841 12 8 827 850 808 813 850 830 20 9 850 850 850 841 841 846 5 10 850 850 813 846 827 837 16 11 831 827 888 831 855 846 26 12 841 874 841 841 813 842 22 13 803 813 798 803 831 810 13 14 850 850 855 855 813 845 18 15 756 765 761 765 756 761 5 16

* Experiment repeated five times using the same weight and diameter (1/8" ball bearings) spheres. E-9

DATA FOR A METAL DETECTOR

BROOKFIELD VISCOSITY STANDARD (VISCOSITY 116P AT 25°C) AT 25°C LIQUID LEVEL OF ABOUT 4" ABOVE THE FIRST COIL CHART SPEED 1 IN/MIN

TURN TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN NUMBER EACH SUCCESSIVE COIL. (FROr-1 STn TOP) 1* 2 3 4 5 MEAN DEVIATION

1 9685 11939 9449 11339 10453 1027 2 11811 11811 10630 9685 12992 11386 1265 3 11339 11339 11102 11339 9685 10961 720 4 10866 9921 10630 10630 11339 10677 512 5 11102 12047 10630 10394 9921 10819 808 6 10630 10157 11575 11811 11811 11197 758 7 11811 11339 10630 11102 11102 11197 429 8 11102 11339 11339 10630 10630 11008 358 9 11575 11339 10630 11339 11811 11339 442 10 11102 9921 10630 11339 11811 10960 720 11 11811 12047 11339 11575 9921 11338 835 12 11339 9449 10394 10630 11575 10677 842 13 11339 9921 10157 11811 10630 10772 794 14 11339 10630 10630 10157 10866 10724 429 15 9921 9921 10157 9449 9685 9827 269 16

* Experiment repeated five times using the same weight and diameter (1/8" ball bearings) spheres. E-10

DATA FOR A METAL DETECTOR

BROOKFIELD VISCOSITY STANDARD (VISCOSITY 116P AT 25°C) AT 25°C LIQUID LEVEL OF ABOUT 4" ABOVE THE FIRST COIL CHART SPEED 2 IN/MIN

TURN TIME IN MILLISECONDS REQUIRED FOR THE SPHERE TO TRAVEL BETWEEN NUMBER EACH SUCCESSIVE COIL. (FRO~1 STn TOP) 1* 2 3 4 5 MEAN DEVIATION

1 10394 10630 10630 9449 10039 10228 498 2 10630 10394 10866 10039 10630 10512 312 3 11220 11811 11339 11575 11575 11504 230 4 10630 10984 10984 10512 10630 10748 220 5 11220 10630 10630 11220 11102 10960 350 6 11220 11575 10630 10866 10984 11055 360 7 11220 10630 11811 10866 11102 11126 445 8 11220 10866 11339 11220 10866 11102 221 9 10631 10866 10630 11220 11575 10984 409 10 10394 11220 10866 10748 10630 10772 305 11 11811 10866 11220 11220 11811 11385 414 12 10630 11811 10866 10984 10512 10961 510 13 10394 10512 11102 10630 10039 10535 386 14 10748 10866 10630 11220 11220 10937 271 15 10394 9803 10039 10394 10394 10205 272 16

* Experiment repeated five times using the same weight and diameter (1/8" ball bearings) spheres. APPENDIX F F-2

VISCOSITY OF NO. 6 FUEL OIL AT 25°C

USE OF RVT MODEL SPINDLE NO. 1

RPM OF THE SPINDLE BROOKFIELD VISCOSITY IN POISE AT 1* 10*

2.5 2.12 ( 5.3) 2.12 ( 5.3) 5 2.18 (10.9) 2.18 (10.9) 10 2.21 (22.1) 2.21 (22.1) 20 2.22 (44.5) 2.22 (44.5)

Values in parenthesis indicate dial reading.

* 1 and 10 indicates that dial reading was noted after one complete rotation of the spindle & then was noted after ten complete rotations, at any given speed. F-3

VISCOSITY OF 20% COM AT 25°C

NO.8 COAL, PARTICLE SIZE -200 + 325 MESH**, NO.6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 1

DAY OF TEST RPM OF BROOKFIELD VISCOSITY IN POISE, NOTED AT THE SPINDLE 10* 20* 40*

Il1MEDIATE 2.5 4.64 (11.6) 4.72 (11.8) 5 4.90 (24.5) 5.00 (25) 5.04 (25.4) 10 5.06 (50.6) 5.07 (50.7) 5.11 (51.1)

1 2.5 5.56 (13.9) 5.52 (13.8) 5 5.56 (27.8) 5.56 (27.8) 5.56 (27.8) 10 5.60 (56.0) 5.60 (56.0) 5.60 (56.0)

4 2.5 7.00 (17.5) 6.00 (16.5) 5 7.02 (35.1) 6.84 (34.2) 7.40 (37.0) 10 8.40 (84.0) 7.40 (74.0) 6.50 (65.0)

8 2.5 8.24 (20.6) 7.80 (17.5) 5 6.72 (33.6) 6.68 (33.4) 10 6.70 (67.0) 6.76 (67.6) 6.82 (68.2)

* 10,20,40 indicates that at any given spindle speed the dial reading was noted at 10 complete rotations of the spindle and then was noted at 20 complete rotations of the spindle and so on i.e. dial readings were noted when the material was subjected to a constant shearing rate over the period of time.

** Particle size of about 95% passing through 200 mesh screen and 60% passing through 325 mesh screen.

() Values in parenthesis indicates the dial readings. F-4

VISCOSITY OF 40% COM AT 25°C

NO.8 COAL, PARTICLE SIZE -200 + 325 MESH**, NO.6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 5

DAY OF BROOKFIELD VISCOSITY IN POISE NOTED AT THE SPINDLE SPEED OF TEST 2.5 RPM 5 RPM 10 RPM 20 RPM

IMMEDI­ 27.2 (1.7) 29.6 (3.7) 30 (7.5) 29.6 (14.8) ATE

1 35.2 (2.2) 32 (4.0) 31.3 (7.9) 30.0 (15)

() Values in parenthesis indicate the dial readings. The readings were noted after 10 complete rotations of the spindle.

** Particle size of about 95% passing through 200 mesh screen and 60% passing through 325 mesh screen. F-5

VISCOSITY OF 50% COM AT 25°C

NO.8 COAL, PARTICLE SIZE -200 + 325 MESH**, NO.6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 5

DAY OF TEST RPM OF BROOKFIELD VISCOSITY IN POISE, NOTED AT THE SPINDLE 10* 20* 40*

IMMEDIATE 2.5 212.8 (13.3) 211.2 (13.1) 211.2 (13.1) 5 197.6 (24.7) 196 (24.5) 194.4 (24.3)

1 2.5 265.6 (16.6) 260.8 (16.3) 249.6 (15.6) 5 224.8 (28.1) 221.6 (27.7) 216.8 (27)

2 2.5 214.4 (13.4) 211.2 (13.2) 206.4 (12.9) 5 188.0 (23.5) 186.4 (23.3) 182.4 (22.7)

4 2.5 204.8 (12.8) 200 (12.5) 195.2 (12.2) 5 180.8 (22.6) 178.4 (22.3) 175.2 (21.9)

8 2.5 187.2 (11.7) 185.6 (11.6) 5 169.6 (21.2) 170.4 (21.2)

15 2.5 187.2 (11.7) 185.6 (11.6) 5 169.6 (21.2) 168.8 (21.1) 165.6 (20.7)

30 2.5 232 (14.5) 176 (11.0) 5 196.8 (24.6) 195.2 (24.4)

* 10,20,40 indicates the number of spindle rotations.

** Particle size of about 95% passing through 200 mesh screen and 60% passing through 325 mesh screen.

( ) Values in parenthesis indicates the dial readings. F-6

VISCOSITY OF 55% COM AT 25°C

NO.8 COAL, PARTICLE SIZE -200 + 325 MESH**, NO.6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 5

DAY OF RPM OF BROOKFIELD VISCOSITY IN POISE, NOTED AT TEST THE SPINDLE 10* 20* 40* 160* 180*

Immediate 2.5 489.6 489.6 (30.6) (30.6)

5 465.6 453.6 440 474.4 474.4 (58.2) (56.7) (55)** (59.3) (59.3)

1 2.5 558.4 553.6 (34.9) (34.6)

5 523.4 512.8 502.8 490.4 491.2 (65.4) (64.1) (62.8)** (61.3) (61.4)

2 2.5 552 547.2 (34.5) (34.2)

5 517.6 508.8 500.8 480.8 476.4 (64.7) (63.6) (62.6) (60.1) (59.6)

* 10,20,40 indicates the number of spindle rotations.

** Dial readings for this mixture was noted up to 180 spindle rotations at a spindle speed of 5 rpm. Dial reading was decreased up to about first 40 rotations (i.e. up to about first 8 mins) and then was steadily increased. The dial readings noted in between 40th and 180th spindle rotation are not shown here. F-7

VISCOSITY OF 50% COM AT 25°C DATA SHOWING THE EFFECT OF PARTICLE SIZE ON VISCOSITY

NO. 8 COAL, PARTICLE SIZE -100 + 200 MESH*, NO. 6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 5

DAY OF BROOKFIELD VISCOSITY IN POISE, NOTED AT THE SPINDLE SPEED OF TEST 2.5 RPM 5 RPM 10 RPM 20 RPM

IMMEDIATE 120 (7.5) 116 (14.5) 114 (28.5) 100 (50)

1 148.8 (9.3) 132.8 (16.6) 132.4 (33.1) 120 (60)

2 252.8 (15.8) 193.6 (24.2) 166 (41.5) 128.4 (64.2)

() Values in parenthesis indicates the dial readings.

* Particle size of about 95% passing through 100 mesh and 40% passing through 200 mesh screen. F-8

VISCOSITY OF 50% COM AT 60°C DATA SHOWING THE EFFECT OF TEMPERATURE ON VISCOSITY

NO.8 COAL, PARTICLE SIZE -200 + 325 MESH*, NO.6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 5

DAY OF TEST BROOKFIELD VISCOSITY IN POISE, NOTED AT 2.5 RPM 5 RPM 10 RPM

IMMEDIATE 19.2 (1.2) 18.4 (2.3) 18.0 (4.5)

1 46.4 (2.9) 40.8 (5.1) 32.0 (8.0)

2 72.0 (4.5) 57.6 (7.2) 59.6 (12.4)

4 180.8 (11.3) 85.6 (10.7) 72.8 (18.2)

() Values in parenthesis indicate the dial readings. The readings were noted after 10 complete rotations of the spindle.

* Particle size of about 95% passing through 200 mesh screen and 60% passing through 325 mesh screen. APPENDIX G G-2

VISCOSITY OF 15% SOM AT 25°C

SOLID SRC, PARTICLE SIZE -200 + 325 MESH*, NO.6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 1

DAY OF TEST BROOKFIELD VISCOSITY IN POISE, NOTED AT THE SPINDLE SPEED 2.5 RPM 5 RPM 10 RPM

IMMEDIATE 5.20 (13) 5.16 (25.8) 5.15 (51.5)

1 7.00 (14.7) 5.68 (28.1) 5.41 (53.9)

() Values in parenthesis indicate the dial readings. The readings were noted after 10 complete rotations of the spindle.

* Particle size of about 97% passing through 200 mesh and 10% passing through 325 mesh screen. G-3

VISCOSITY OF 30% SOM AT 25°C

SOLID SRC, PARTICLE SIZE -200 + 325 MESH*, NO.6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 4

DAY OF TEST BROOKFIELD VISCOSITY IN POISE, NOTED AT 2.5 RPM 5 RPM 10 RPM 20 RPM

IMMEDIATE 24.8 (3.1) 22 (5.5) 20.6 (10.3) 19.1 (19.1)

1 29.6 (3.7) 26.4 (6.6) 24.4 (12.2) 22 (22.0)

() Values in parenthesis indicate the dial readings. The readings were noted after 10 complete rotations of the spindle.

* Particle size of about 97% passing through 200 mesh and 10% passing thrugh 325 mesh screen. G-4

VISCOSITY OF 40% SOM AT 25°C

SOLID SRC, PARTICLE SIZE -200 + 325 MESH*, NO. 6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 5

DAY OF TEST BROOKFIELD VISCOSITY IN POISE, NOTED AT 2.5 RPM 5 RPM 10 RPM 20 RPM

IMMEDIATE 73.6 (4.6) 62.4 (7.8) 54 (13.5) 47.4 (23.7)

1 92.8 (5.8) 76.8 (9.6) 66 (16.5) 58 (29)

() Values in parenthesis indicate the dial readings. The readings were noted after 10 complete rotations of the spindle.

* Particle size of about 97% passing through 200 mesh and 10% passing thrugh 325 mesh screen. G-S

VISCOSITY OF 50% SOM AT 25°C

SOLID SRC, PARTICLE SIZE -200 + 325 MESH*, NO.6 FUEL OIL USE OF RVT MODEL SPINDLE NUMBER 6

DAY OF TEST BROOKFIELD VISCOSITY IN POISE, NOTED AT THE SPINDLE SPEED 2.5 RPM 5 RPM 10 RPM 20 RPM

IMMEDIATE 784 (19.6) 604 (30.2) 489 (48.9) 400 (80.0)

1 760 (19.0) 584 (29.2) 481 (48.1) 400 (80.0)

2 728 (18.2) 550 (27.5) 441 (44.1) 364 (72.8)

4 956 (23.9) 698 (34.9) 557 (55.7) 456 (91.2)

8 876 (21.9) 696 (34.8) 595 (59.5) 492.5 (98.5)

() Values in parenthesis indicate the dial readings. The readings were noted after 10 complete rotations of the spindle.

* Particle size of about 97% passing through 200 mesh and 10% passing thrugh 325 mesh screen. THESIS ABSTRACT

The present work reports the results of the study made on the stability and rheological properties of coal-oil mixtures, solvent refined coal-oil mixtures and low ash coal-oil mixtures.

50/50 by weight mixtures of Ohio No. 8 Coal/No. 6 Fuel Oil, Solid Solvent Refined Coal/No.6 Fuel Oil and Low-ash Coal/No.6 Fuel Oil, were prepared for evaluation of the stability in which the particle size of the coal and the temperature were varied. The stability was assessed by the physical pendulum method by measuring a e.G. drop for the mixture. Stability of SRC/oil mixtures were found to be higher than the other types of coal-oil mixtures.

Viscosity of the coal-oil mixtures were measured by a rotational type viscometer. Coal-oil mixtures were found to be thixotropic in nature particularly above 30 percent coal content. The viscosity of SRC/Oil mxiture was found to be higher than the other types of coal-oil mixtures.

Direct coal-liquefaction experiments included the dissolution of Ohio No. 4A and Ohio No. 8 Coal in a solvent such as phenanthrene as well as in a mixture of organic solvents. It was found that phenanthrene was not a suitable solvent for the atmospheric dissolution of Ohio coals. Experiments carried out using the mixture of organic solvents in an autoclave resulted in a sizeable amount and a good quality Low-ash coal.