AUSTRALIAN ATOMIC ENERGY COMMISSION
RESEARCH ESTABLISHMENT
LUCAS HEIGHTS
A BRIEF SURVEY OF PROCESSES
FOR HEAVY WATER PRODUCTION
R. K. RYAN
ABSTRACT
A brief review is given of methods for the production of nuclear grade heavy water, including water electrolysis, distillation, and chemical exchange processes.
Present world production comes mainly from the U. S. A., however Canadian plants will shortly produce much of the world supply. These plants use the HgO/HgS process, the only one developed to industrial scale. Sufficient develop- ment of the NH,/Hp process has proceeded for its use industrially.
Heavy water production as a by-product of established industries appears attractive provided a process matched to the feed supply is available. There are many possible processes that have not been developed. CONTENTS Page No;
1. INTRODUCTION 1
2. SOURCES t 1
3. SEPARATION METHODS 2 3.1 Water Electrolysis . 2 —3.2 Distillation 2
3.2.1 Hydrogen distillation 3 3.2.2 Methane distillation 3 3.2.3 Ammonia distillation 3
3.3 Chemical Exchange Processes 3
3.3.1 HgS/HpO exchange (GS process) 4
3.3.2 Hp/NH, exchange 4 r c o
3.3.3 H20/H2 exchange 5
4. PRESENT WORLD PRODUCTION 5
5. INDUSTRIES CAPABLE OF PRODUCING BY-PRODUCT HEAVY WATER 6
6. ADDITIONAL POSSIBLE PROCESSES FOR HEAVY WATER PRODUCTION 6
7. SUMMARY . 6
8. ACKNOWLEDGEMENTS 7
9. REFERENCES 7
Table 1 Feed Volume Requirements to Produce 100 short tons of D?0 per Year Table 2 Separation Factors of D^O Processes Table 3 Heavy Water Plants in Operation and Under Construction Table 4 Heavy Water Plants Proposed Table 5 Variables Affecting Production and Costs - GS Process Table 6 Industries Capable of Producing By-Product Heavy Water Table 7 Potential Processes Examined (Barr and Drews 1960)
Appendix 1 Definition of Separation Factor
Figure 1 Heavy Water Inventory v. Unit Rating in Megawatts (Electrical) (After Cochran 1966)
Figure 2 Chemical Exchange Processes 1. INTRODUCTION The heavy water inventories for various reactors differ as shown by Cochran (1966) in a chart of heavy water inventory per MWe versus unit ratings (repro- duced in Figure IK Cochran, discussing the chart, suggested: "Curve 1 represents heavy water inventory resulting from a recent Canadian heavy water reactor design optimization for a range of unit ratings. This curve appears compatible with the majority of known heavy water reactor designs. However, there are exceptions at considerably lower inventory levels. # Bohunice has an inventory of 0.5 short tons per MWe because of its low burnup, about 3,000 MWd/tonne. The boiling light water reactor with 1.42 ** per cent. U02 enrichment, according to paper AECL-2010, would have an in- ventory of about 0.34 short tons per MWe. Accordingly, curve 2 represents a possible minimum inventory level that may be encountered in the future". Estimates of heavy water requirements for any country thus depend on the size and number of reactors to be built. Assuming initial reactor installations would be in the range 200 to 500 MWe, the heavy water inventory would be 0.8 to 1.0 short tons/MWe, if natural uranium is assumed to be the fuel. 2. SOURCES Theoretically any hydrogen-containing compound is a potential source of deuterium and, hence, heavy water. However, many compounds have insufficient hydrogen content to be used economically as a source of deuterium. One of the important requirements for a source of nuclear grade heavy water is a pure feed material. Very large quantities of feed material are necessary to recover rather small quantjties of heavy water since the deuterium content of natural hydrogen sources, for example HgO and CH^, is only about 0.015 mole per cent. (Rae 1965> Bebbington and Thayer 1959^. The quanti ty of feed material is further increased by the inefficiency of recovery in some processes. For example, in the GS (Girdler-Spevak or Girdler-Sulphide) process only 20 per cent.of the deuterium present is recovered (Becker 1962K The only feed materials available in suf- ficient quantity are hydrogen, ammonia, methane and water and typical examples of the quantities required to separate 100 short tons of DgO per year are given in Table 1. * A 150 MWe heavy water power reactor in Czechoslovakia for completion in 1968. ** Pon et al. (1964). 3. 2. 3.2.1 Hydrogen distillation 3. SEPARATION METHODS Hydrogen distillation has a high separation factor, but its disadvantage The several methods available for the separation of deuterium from the feed, is the extremely low boiling point of liquid hydrogen, about 20°K. include electrolysis, distillation, arid chemical exchange. Flynn (I960) described a pilot plant for the distillation of hydrogen The"'separation factor (a) is defined as the ratio of the heads abundance to produce deuterium, which was built in 1958 at the National Standards Labor- ratio to the tails abundance ratio (Appendix 1). Separation factors for several atories cryogenic engineering laboratory at Boulder. The preliminary concen- possible processes are compared in Table 2. With other factors equal, the process tration stage, which was the only one piloted, consisted of a 6 inch diameter
with the higher separation factor is the belter process. Although the separation tower with an equivalent D00 production rate of 45 lb/8,000 hour year. Stouls & * factor is of great importance since it determines plant sixe, flow rates, etc., (1965), in a patent described an apparatus for the production of deuterium by there is no correlation between Ct and the economic prospects of a process. The hydrogen distillation. At Nangal in India (Table 3) a hydrogen distillation energy consumption and plant cost have to be carefully weighed in each case. plant for the production of deuterium is operated in association with a ferti- lizer plant (Gupta 1965). Becker (1962) in discussing the recovery of deuterium found water electrolysis too costly for pre-enrichment but suitable for final concentration because the 3.2.2 Methane distillation process is simple and easily controlled. Water distillation also is useful only British American Oil Company is developing methane distillation as a source for final concentration, but low temperature hydrogen distillation, which has a of heavy water. Methane distillation is useless at atmospheric pressure (sep- high separation factor, is attractive provided the difficulties associated with aration factor - 1.0002). However, the factor increases at elevated pressure, the low temperatures are overcome. He found that chemical exchange methods are being largest at about 600 p.s.i.a. (Pogorski 1965). Further improvements are most economic, particularly the GS process, which has been run industrially at obtainable by application of ma*gnetic and electric fields and also by use of Savannah River. The H20/H2 and H2/NH3 exchange processes are preferable because additives to give ternary systems. There is no problem from vei^y low temper- of their higher theoretical separatiots factor, but. are not so highly developed. atures as required in the hydrogen distillation process, and the process may 3.1 Wat er Electrolysis actually make use of high pressure liquefied methane if available, for example, Water electrolysis has a high separation factor (Table 2.}. However, the in U. S. A. where helium is recovered from natural gas (C.N.T. 1966a). Shamsul Huq (1966) discussed this process for use in conjunction with fertilizer pro- energy requirements are very high. Some of the energy may be recoverable by duction from natural gas. fuel cells, but generally the process can only be used where power costs are j extremely low and even then only for final concentration (Bebbington et al.1964). 3.2.3 Ammon ia d i st illati on s Alvarez (Alvarez et al.1964) and Otero (Otero and Gispert, x964, Otero et al •, Barr and Drews (1960) discussed ammonia distillation as a possible process I960) are developing electrolytic cascades and burners and are piloting this for deuterium recovery. The vapour pressure and latent heat of ammonia compared process. with water would be advantageous in this distillation if the separation factor 3.2 Distillation were large enough. However^ it is too low for economic deuterium recovery. (Table 2). Four different distillation processes are of interest. Water distillation *» is only of interest for final concentration where simplicity and operational 3.3 Chemical Exchange Processes safety rather than economics are of paramount importance. Proctor and Thayer Chemical exchange depends upon minor differences in the chemical (1962) described an improved vacuum distillation method. The other three pro- properties of isotopes causing a shift in equilibrium of chemical reactions. cesses are (a) hydrogen distillation, (b) methane distillation, and (c) ammonia Examples are: distillation. '.4 5. 4. improved performance using cesium and rubidium amide catalysts. This process (1) may be either monothermal or bithermal. (Figure 2). The small plant at HDO H2S(g) ;» U) 8 Mazingarbe in France (Table 3) is of monothermal type (Rae 1966) and has been H (2) HD(g) 2(g) discussed by Lafrancois (1964) . He suggested that the bithermal exchange may (3) become economically preferable if the low temperature tower is held at -70°C HDD KD(g) or lower. Exchange processes are of two types, monothermal and bithermal (Figure 2). Rae (private communication) has indicated that assessments by A.E.C.L. Monothermal processes allow the recovery of most of the deuterium in the of heavy water processes have shown that the NHj/Hg process does not appear feed as the gas is produced by chemical decomposition of the liquid and then as attractive as at first thought. Pilot plant studies will be undertaken contacted with the incoming liquid, the temperature of the reaction being when it is clear which process offers the most promise of worthwhile cost chosen to give a sufficiently large separation factor. The economic limitation reductions . on this process is the cost of the chemical decomposition step, for example, 3.3.3 exchange ammonia decomposition is feasible while water decomposition is not. • A bithermal process using liquid phase Exchange is thermodynamically Bithermal processes use the difference between separation factors at two favourable. However, a better catalyst than Pt on colloidal charcoal is needed temperatures. The overall recovery of deuterium from the feed is limited by (Rae 1965) . This process is being given some attention in Germany where the temperature levels used. Bithermal processes require two contactors while Friedrich Uhde GmbH (Dortmund, West Germany) in co-operation with Degussa and monothermal processes require a contactor and a reaction vessel which means that Karlsruhe Nuclear Research Centre have built a single stage dual temperature a similar complexity of equipment is needed for both processes. system using a Pt on activated charcoal catalyst suspended in water. The Barr and Drews (I860) described a large number of possible reactions. How- French have also studied this using colloidal Pt catalyst (Laws 1965) . Halpern ever, only a few have been studied extensively, the GS process (HgS/HgO exchange), and James (1966) have studied Ru-III C1-- as a catalyst in the Dg/HgO exchange the NH,/Ho exchange, and the HgO/Hg exchange. Separation factors are given in reaction. Table 2. 4. PRESENT WORLD PRODUCTION 3.3.1 H^S/HpO exchange (GS process) Table 3 lists heavy water plants in operation and under construction, in- This process has been highly developed, being the process used at Savannah dicating owners, location, and capacity. Table 4 shows some proposed plants. * ' » River for many years (Table 3) and that proposed for the Canadian plants at Glace The main world supply of heavy water is manufactured at Savannah River, Bay and Pointe Tupper (Table 4). The process is ionic and has been well described U. S. A. by the GS process. 'Only part of the plant is in operation and the (Rae 1965, 1966; Bebbington and Thayer 1959, Spevak 1949, C. A. Laws 1964). older Dana plant is out of operation. Proctor and Thayer (1962) suggested ways to improve the GS process, reducing both t In Canada A.E.C.L. has licensed two plants for the production of heavy the investment costs and the operating costs. Corrosion in the process is discus- water by the GS process. Deuterium of Canada has almost completed a 200 short sed by Thayer and DeLong (1962). Major variables affecting production and costs tons DgO/year plant at Glace Bay, Nova Scotia, which may be extended to 500 are given in Table 5 (Bebbington et al. 1964). A very sensitive method of control short tons DgO/year, while Canadian General Electric has won the contract for for the GS process was found to be the ratio of deuterium concentrations on the the second plant to be located on the Cape Breton side of the Straits of mid-plates of the hot and «old columns (Morris and Scotten 1962). Causo at Pointe Tupper, Nova Scotia (C.N.T. 1966b) . Both Canadian plants have 3.3.2 1U/NH, exchange power plants nearby which will supply steam and electric pow^r at a low fixed ••-£ ^iin-iJi-iTL — . _.. -_ilnfrr-_ This process has a more favourable separation factor than the GS process price. (Table 2). However, the reaction is not ionic and a catalyst is needed. Pot- assium amide is the common catalyst. However, Lafrancois et al. (1962) claimed 7. 6,
Small<-r quantities arc produced in Norway, India, Switzerland, and France. Choice of processes must depend on the feed material source. However, it must be remembered that the HgO/ H«S process is the only one that has been Th'1 processes used in thcsv plants vary greatly. developed on an industrial scale and the NH _/Hp process has been developed
liquefied tc separate helium. Barr, F. T., and Drews, W. P. (1960). - The future of cheap heavy water. 6. ADDITIONAL POSSIBLE PROCESSES FOR HEAVY WATER PRODUCTION Chem, Eng. Prog. 56 (3):49.
Barr and Drews (I960) have listed pos Able processes for heavy water pro- Becker, E. W. (1962). - Heavy water production. I.A.E.A. Review Series. No. 21. duction. (See Table 7). They considered some of these processes attractive Bebbington, W. P., Proctor, J. F., Scotten, W. C., and Thayer, V. R. (1964).- enough for further study. The Hg/HpO-hydrazine exchange reaction may prove Production of heavy water In U. S. A. Third United Nations Inter- attractive if, as they suggest, the hydrazine acts as a catalyst similar to national Conference on the Peaceful Uses of Atomic Energy. the amide in the K /NH_ reaction. If a more effective catalyst is found, the 2 A/Conf 28/P/290. ?K,/H90 exchange reaction may prove of value. They suggest that 30 to 40 per O Ct Bebbington, W. P., and Thayer, V. R. (1959). - Production of heavy water. cent, greater capacity may be obtained in the same size towers as used for the C.E.P. 55 (9):70-78. GS process. HI/HgO , HCl/KgO, and HBr/HgO are considered but they all appear to be less attractive than a GS plant. The possibility of deuterium being Cochran, D. R. (1966). - The role and requirements of heavy water in Canada evolved instead of hydrogen in an electrolysis reaction appears attractive. and the World. Paper presented at the C.N.A. Conference, Winnipeg, There is nc method presently available for doing this. However, ionic reson- Canada, May 30, 31 arid June 1, 1966. 66-CNA-301. ance effects may prove useful. C.N.T. (1966 a). - The newest variant. Canadian Nuclear Technology, Jan. - Feb. 1966. 7. SUMMARY . The more important processes for the recovery of heavy water have been C.N.T. (1966 b) . - Canso N. S. site for heavy water plant. Canadian Nuclear reviewed briefly. There are many practical problems in these processes such Technology, July -Aug. 1966. p. 30. as efficient energy recovery, which have not been considered. The optimum Flynn, T. M. (1960). - Pilot plant data for hydrogen isotope distillation. process will combine a high separation factor, large throughput per unit size, C.E.P. 56 (3,):37-42. and efficient energy recovery. 8.
Gupta, 3. N. (196b^. - India chooses Candu Tor KalpakKam, Canadian Nuclear Shamsul Huq, A.K.M. (1966). - AECD/CH/8. Technology 4 (3t:2S. Spevak, J. S. (1949). - lMX)-85. Halpern, .7., ami James, R. J. (1966), - Homogeneous catalysis of ^/HgO exchange by Ru(in^ 01,. Evidence for heterolytic splitting of Stouls, L. (1965^. - Methods for the production of deuterium by distillation of hydrogen. U.S. Patent 3,216,800. H,.C» . Can. ,1. Chera. •*-*•44— : 671-75. Lafrancois, B., Lfrat. J. M., and Roth, K. (1964). - Study on the pro- Thayer, V. R., and De Long, W.'B. (1962). - Materials of construction for duction of heavy water in France. .Third United Nations International the dual temperature exchange process for producing heavy water. Confer»?ncc on the Peaceful Uses of Atomic Energy. A/Conf 28/P/91. C.E.P. Symposium Series 58 (39):86-93.
Lafrancois, B., Sack, H., Vaniscotto, C., and Dirlan, G. (1962). - Caesium Walter, S., and Schindewolf, U. (1965). - Enrichment of D through high and rubidium Catalyst 2 in deuterium enriching process. Canadian pressure isotopic exchange between Hg and liquid NH, in a hot-cold Patent 637.,77? (March 6, 1962^. installation. Angew. Chem. Interm. Ed. Engl. 4:597. (July 1965) Laws, C. A. (1964). - Why the GS process still tops competitors. C.N.T. 3 abstracted in N.S.A. 19-44574. (1):36-4C. Laws, C. A. (1365). - Hea'/y water : Western deuterium's new track. C.N-.T. 4_ \C?\ t. / ,t Rae, K. K. (1965). - AECL-2503. Rae, H. K. (1966). - AECL-2555. TABLE 3 TABLE 1 HEAVY WATER PLANTS IN OPERATION AND UNDER CONSTRUCTION Capacity References Process Owner Location Short tons Feed Volume Requirements % DgO Recovery D-O/year Feed Material .. Rae 1965 8 5 Unknown H2/steam exchange and Norsk Hydroelektrick Rjukan and Glam Fjord Hydrogen 10 S ft /day electrolysis 20 100* 2.55xl07 S ft /day Koaelstofakti ss Norway Methane Unknovm Rae 1965 14 1,500 short tons/day dist. + elect, Fertilizer Corp. Nangal, India Anaaonia pre-enrichment India 20$ C.N.T.1966a 1.48x10 * Imp. gal/ day Enser Werke AC Dotnat/Eng, Switzerland 3 Water exchange U.o .A.Ci.U . Aiken S.C.,U.S.A. 180 Deuterium of Glace Bay, N.S. 200 Canada r TABLE 2 NHL/Kg- exchange C.E.A. Mazingarbe, France 20 SEPARATION FACTORS OF D.,0 PROCESSES Under construction Theoretical Separation Factor TABLE 4 Method ^rocess ••WMM^MMilMMmMHMn ..I HEAVY WATER PLANTS PROPOSED Water electrolysis Electrolysis Water distillation Distillation Capacity Process Location Short tons Hydrogen distillation D2-0/year Methane distillation* exchange CGE, Pointe Tupper, N. S. 500 15 p.s.i. # Not available Deuterium of Canada, Glace 200 [Methane distillation Bay, N.S. 660 p.s.i. Nangal or Bihar, India. 200 Ammonia distillation Electrolytic (Pt cat. Sabinanigo, Spain ' 0.55 short tons/year exch.) H S/H,,0 dual tempera- Chemical exchange 02 £ Hg distillation or Nat. Gas Fertilizer Factory, 14.61 short/tons year ture exchange Hg/NHg exchange or Fenchuganj, Pakistan 1.42 H2/NH3 dual tempera- CH4 distillation ture exchange H2/NH3 exchange Germany - Semi-industrial t 1.44 H2/H2C dual tempera- ture exchange * Deuterium of Canada proposes to increase the size of plant to 500 short tons year. ** Otero and Gispert (1964). t Walter and Schindewolf (1965). TABLE 7 Page TABLE 5 POTENTIAL PROCESSES EXAMINED (From Barr and Drews 1960) PROCESS NUMBER PROCESS NAME COMMENTS Chemical Exchange Processes (See also Processes Nos. 55-80, 95, 96, 98) Effect on Production Rate Variable Hydrogen/water dual-temperature Might have good potentiality if the 1% decrease A * l£* deviation from the optimum exchange exchange could be made to go fast liquid to gas flow ratio enough. No promising adaptations 1-|^ increase so far. 1°C decrease in cold tower temperature 1% increase 1°C increase in hot tower temperature Ammonia/hydrogen dual-temper- Independent study made of this system. Directly proportional ature exchange No advantage over the HgS/HgO process. Gas flow rats Directly proportional Phosphine/water dual-temper- Reaction rate probably too low, but Gas quality (#HgS) ature exchange separation efficiency higher than 1% increase An increase of 15 p.s.i. in gas that of the HgS/HgO process. pressure Diborane/hydrogen exchange Separation factors for this system not known. Unless it has unusual charac- teristics it will not be outstanding because of the high refrigeration load. TABLE 6 Hydrogen sulfide/water dual- Target for comparison. See also Process temperature exchange No. 98. Methane/hydrogen exchange Exchange data on all show low reaction Ethane/hydrogen exchange rate, extensive decomposition, or both. Propane/hydrogen exchange However, incentive for such a process Industry Butane/hydrogen exchange is great since methane in natural gas Isobutane/hydrogen exchange is the largest single source of hyd- Naturally available rogen next to water. Cyclohexane/benzene-hydrogen Involves isotope exchange equilibria in Blue water gas and water gas shift exchange a hydrogenation-dehydrogenation re- Gas industry action. Slow rates and high heat of NH, synthesis reaction probably make it not eco- CO>H synthesis nomical . o Petroleum industry 11A Cyclohexane or benzene-hydrogen Avoids the high heat of reaction, but Chlorine production exchange Electrolytic cleaning quick, easy equilibration not expected. 12 Glycol/water exchange Separation factor close to unity at all NH, synthesis temperatures. Ammonia o Fertilizer 13 Aromatics/ammonia ^exchange Separation factor probably low. Urea production HNO, production 14 Acetone/hydrogen exchange o Separation factor probably good, but ex- Explosives change rate low. 15 Mercaptan/water exchange Suggested during the 1941-45 development Methane Naturally available work. No new information obtained. HC1 production The process might still be attractive. NHV production v» (continued) Page 2 TABLE 7 (Continued) Page 3 TABLE 7 (Continued) PROCESS NUMBER PROCESS NAME COMMENTS COMMENTS PROCESS Processes Involving Electrolysis (See also Processes Nos. 85 and 84) NUMBER PROCESS NAME gUMBgL. sasssuSS* 98) (continue(J) ^^^gae_pESeSgSU8£e^^Pry^^. Nos. SS-SO.JS^^ 32 Lowering overvolwges in an Could improve electrolytic process which • Separatio. n factor„ _ x. s probabl^v.^V.o'Klyv goodcrOOd ,. buDUtT electrolytic process by the already looks good, but would not use of solutes make unattractive process economic. 16 Enols and ketones'/hydrogen exchange rates low. exchange Probability of success low. Expected to have about the same separ- 33 Reoxidizing hydrogen with Secures by-product credits for an elec- 17 Potassium amide/hydrogen and ation factor as the ammonia-hydrogen substituted amines/hydrogen system: Choice of the proper amine metallic oxides to make pure trolytic process, but limited by exchange metal by-products metals production rate. * substituent may avoid the high vapour pressure associated with ammonia, which makes high-pressure operation necessary, 34 Electrolysis through osmotic Considered in connection with Process diaphragm No. 83. See also Process No. 95. 35 Trail-type operation at elec- Separation factor likely to be poor. Somewhat less attractive than the Trail Ion-Exchange resin/water ex- trolytic chlorine plants operation, which, does not compete change "• with large scale HgS/EUO plants. 36 Simple reversible electrolysis Little promise for the originally pro- 19 Thorium hydride/hydrogen ex- change Exchange rate probably too slow to be posed process using two liquid phases. 20 Potassium hydride/hydrogen ex- of interest. See process No. 83. change Adsorption Processes (See also Processes Nos. 85-88) 21 Sodium -hydride/hydrogen ex- change 37 Hydrogen on palladium 38 Hydrogen on platinum ^ Inventory costs too high. 22 Cesium hydride/hydrogen ex- Slow exchange rate; inventory costly change and limited. 39 -Hydrogen on platinum re- 23 Rubidium hydride/hydrogen ex- Detailed study of the char system change forming catalyst (Process No. 44) made. General con- 40 Hydrogen on hydro forming clusion was that H adsorption systems Exchange apparently rapid, and counter- catalyst 2 24 Uranium hydride/hydrogen ex- current fluid solids tower could be might be attractive if good separation change used. However, large inventory would 41 „ Hydrogen on aromatizing factor obtained without going too low be expensive, and the separation catalyst in temperature but that reaching this 42 Hydrogen on alumina goal is unlikely. Char system would factor probably not exceptionally 43 Hydrogen on silica gel good. See also Process No. 96. require separation factor of at least 44 Hydrogen on char 100 at -400°F, or 50 at -260°F. Gadolinium hydride/hydrogen 45 Liquid-liquid extraction of Triethylaraine was attractive solvent but 25 G£ water exchange ^ Separation factor probably low. Supply separation factor and mass transfer rate were low. 26 Lithium hydride, lv«l*osen ex- of 0'! and Ce limited. change 27 Cerium hydride/hydrogen ex- 46 Liquid nitrogen absorption Other work was to be done in this field, change of hydrogen so no evaluation made. Diffusion Processes * 47 H« diffusion through porous Decomposition of water by Generally unsuited to tower or cascade , barrier alkali metals operation. Some might be useful for Decomposition of water by 48 Hp diffusion through vapor- No evidence that any of these processes (47-52 concentration of feed to existing barrier calcium carbide operation. See Process No. 88. would be attractive. Successful ap- Decomposition of water in 49 Thermal diffusion (Clusius- lication of diffusion separations has methane-steam reforming Dickel) been to more valuable materials, with high- er starting concentration (e.g. U-235). Bacteriological decomposition (continued) and utilisation (continued) •• TABLE 7 (Continued) Page 5 TABLE 7 (Continued) Page 4 PROCESS NUMBER PROCESS NAME COMMENTS PROCESS COMMENTS NUMBER PROCESS NAME Additional Exchange Processes (continued) Diffusion Processes (continued) /• 67 Amyl. alcohol/water exchange -^ Separation factor close to unity. No evidence that any of these processes woaM 68 Methyl aleohoI/water exchange r 50 Ion diffusion tf 'ough exchange be attractive. Successful application of resin diffusion separations has been to more 69 Ethanethiol/water exchange Separation factor about same as for 51 Liquid thermal diffusion valuable materials, with higher starting H«S/H,,0 system. 52 Hydrogen diffusion through concentration (e.g. U235). 70 Nitrophenol/water exchange palladium 71 Phenol/water exchange Nos. 90-94, 97] 72 Resoreinol/water exchange , Separation factors expected to be low. Distillation Processes (See also Processes 73 Sugars water/exchange Water distillation excluded from this 74 Vinyl acetic/acid water 53 Rotating-cone column for low study, but idea might be useful for exchange pressure drop in water distil- maintaining good separation factor by lation low pressure. 75 Acetylene/water exchange Separation factors for these base- 76 Chloroform/water exchange catalyzed reactions expected to be low. To control fouling of exchangers by CO 54 Falling-drop condensation in ice, but technique not necessary if 77 Complex cobalt and copper- Between water vapor and a water solution hydrogen distillation reversing exchangers perform satis- ammonia salts/water ex- of the salt. Separation factors factorily. change probably low.. 78 Aniline hydrochloride/water exchange Exchange rate and separation factor low. V Low separation factor expected. 'Benzene/hydrogen chloride ex- 79 Mono- and dimethylamine hyd- 55 rochloride/water exchange change I Separation factor probably close to Enols and ketones/water ex- 80 Halogen acid/water exchange Not economical unless solubilities and 56 unity. humidities obtainable can be demon- change strated to be much lower than assumed Separation factors about same as in am- Alizarin/hydrogen exchange in this 'study. 57 monia/hydrogen system. The lower o-Anisidine/hydrogen exchange vapour pressures might help if ex- 58 o-Toluidine/hydrogen exchange 81 Sodium sulfate decahydrate/ Negligible separation effect. 59 change rates were good. water exchange Separation factor no better than for •Dimethylglyoxitne/nydrogen ex- Partially Concentrated Sources (See also Process No. 83) 60 water/hydrogen system. change 82 Hydrogen residues from hyd- No great possibilities seen for this system Poor separation factor. rogenation Hydrogen throughput unlikely to be Hydrogen chloride/hydrogen 61 large enough to give a considerable pro- exchange duction of deuterium. Separation factors about same as for am- Additional Electrolysis Processes Indole/water exchange monia/water exchange, which is close 62 Methyl indole/water exchange 83 -Diaphragm-separated reversible Little hope for making an economical 63 to unity. electrolysis process of this system. However, the idea is of considerable technical Separation factors for these systems also interest. 64 Pyrrole/water exchange probably small. Indene/wat«r exchange 65 84 Direct electrolytic release Could be attractive if a separation factor Avoids hydrate formation problems in H«S/ of deuterium of 10 or better were demonstrated for 66 Hydrogen sulfide/methyl HpO system, 'but these apparently- not alcohol exchange the preferential release of deuterium. serious. No improvement in exchange Might be achieved by using pulsating . efficiency. direct current at a deuterium ion resonance fre-juency. (continued) (continued) •N, TABLE 7 (Continued) Page 6 FKGCBSS APPENDIX I PROCESS HAMS COMMENTS Additional Adsorption and Absorption Processes Adsorption of hydrogen on Conclusions of the study on Process No. 44 are pertinent. However, re- nicXei Component d ions are shovm Adsorption of hydrogen on frigeration would not be required. eflnlt la the following calcium ^1 Adsorption of water on Water adsorption on char may have Heads silica gel favorable application as feed water 68 Adsorption of water on char concentrating process. V 3J Hydrogen absorption in water Separation factor ejcpeeted to be low. Ajdit j.)naI Pi JT i nation. Processes ;O Dual-temperature water dis- Vapor recompression is more economical Stage 1 tillation method of heat conservation. Jl Methane distillation Less attractive than ammonia distil- Feed lation (Process No. 94). L 92 Silanec distillation Not attractive without unusually good i Tails yS Hydrogen fluoride distil- separation factors. Feed would have x i T " lation to be by equilibration with water, L satisfactory form of which is not l readily apparent. X " Xl 94 Ammonia distillation Could be distinctly superior to water where L = stream flow rate distillation, but this depends on confirmation of anomalous vapor pres- ure of NHJ). * . atom fraction of recoverable isotope Abundance Ratio * § - x A.jdi* ional Exchange Processes ,»rtc 1 - x 35 Kydrazi ne-water/hydrogen Has promise. Separation factor of the Separation Factor = a = -LL exchange order of the HgO/Hg and the NH^Hg systems. Presence of hydrazine or substituted hydrazine might give JLL fc-x1') useful exchange rates. See also U-x') Process 17. Titanium hydride/hydrogen, Reported to have reasonably good sepa- exchange ration factor. Fluid solids exchange tower could be used S^e also Processes Nos. 19-27. 37 Zone-melting of water Zone melting is the solid/liquid analog \of batch distillation. No possibility Y>f economical application seen. 98 Liquid-liquid hydrogen sul- Study indicated that liquid/liquid hyd- fide/water exchange rogen sulfid*/ water exchange could not compete with the present vapor/ liquid process. 1-4 LEGEND: 1 DOUGLAS POINT 2 EL4 (France) 3 BAVARIA 1-2 4 MARVKEN AVERAGE Q-4 SHORT TDNS/MWc CURVE 2 POSSIBLE MINIMUM 02 IOO 2OO 3OO 4OO SCO 6OO TOO SCO 9OO IOOO IIOO COO UNIT RATING (MWc) FIGURE 1. HEAVY WATER INVENTORY v. UNIT RATING IN MEGAWATTS (ELECTRICAL) (After Cochran, 1966) /•toff FEED i1 NH, A SYNTHESIS i Jl___^._ { CATALYST 1 1 W || 'Vf^ 1 •• i COLD STRIP TOWER 1 * I FEED 1 •--Jrj SYNTHESIS GAS i "*" } i ii COLD TOWER $ •s* CATALYST i : I IN NH3 i HEAT EXCHANGER 1 \ 1 ^ *i M t FINISHING STEPS COLD TOWER 2 -3ft aITALYST t\/APORATOR ! * *» ' I f A j CRACKING •MM WASTE FINISHING STRIPPER STEPS MAZfNGARBE, NH,Al2 PLANT MONOTHERMAL SAVANNAH RIVER, GS PLANT BtTHERMAL FIGURE 2. CHEMICAL EXCHANGE PROCESSES