Laboratory and Plant I
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Nov., 1gr3 THE JOURNAL OF I-VDUSTRIAL A N D ENGINE E RI .VG C H E MIS T R Y 935 Acknowledgments are due Assistant Professor 111. The results of our fertilizer inspection analysis G. F. Lipscomb for his careful oversight of the work this past season point to the same fact; i. e., that of the students; to the students themselves and to there is danger of falling off in the available phos- Mr. E. L. Hutchins for furnishing us with materials phoric acid when calcium cyanamid and acid phos- and for the use of his experiments and results. phate are used together as ingredients of a mixed CONCLUSIOXS fertilizer. I. From experiments conducted in this laboratory, IT-. The results of all these experiments indicate it has been shown that when cyanamid is mixed with that the time element has an important influence in de- acid phosphate in the ratio of one part of the former termining the increase of insoluble phosphoric acid, to 6.2j or 8.33 or even 9.8 of the latter, there is, on and must be considered in addition to the elements standing, a gradual increase of the insoluble and con- of temperature and the alkalinity of the cyanamid. sequent decrease of the available phosphoric acid in the mixture, and that this is true whether the mix- T-. It appears from the facts given in this paper, ture consists simply of the acid phosphate and cyan- that, though it may be said that the effect of mixing amid, or whether ammoniates and potash salts are cyanamid with acid phosphate will not injure the fer- also present. tilizer from the farmer’s standpoint, the manufacturer 11. The experience of at least three manufacturers must exercise some care as to the amount of the cyan- working on a factory scale has shown that there is a amid used in a mixture, else his mixture may, upon decrease of the available phosphoric acid when cal- inspection and analysis, be found deficient in available cium cyanamid and acid phosphate are used in mixed phosphoric acid. fertilizers in the ratio of one part of the former to 6. 25 CHBMICALDEPARTYENT or 8.33 of the latter, thus confirming our own work CLEMSONAGRICULTURAL COLLEGE done on a small scale. SOUTH CAROLINA I LABORATORY AND PLANT I THE DESIGN OF AN EXPERIMENTAL WOOD DISTILLA- United States by both of us, we selected the type of TION PLANT plant described in this article as most nearly applicable By H. K. EBNBON AND MARCDARRIN to economical operation in the distillation of mill waste. Received August 18, 1913 The plant thus designed has been erected cooperatively The utilization of waste wood in the Pacific Sorth- by the United States Forest Service and the University west has recently attracted much attention. The of Washington and is now in operation. In this article interest lies partly in the necessity of clearing the only the design of the plant will be described since logged off or “cut over” lands which now number the results obtained will be the subject of later publica- over three million acres in the State of Washington tions by the Forest Service. alone. In a more popular sense, the interest, however, The general layout of the plant is indicated by the centers about the waste wood of the sawmills. In legend descriptive of Plate I. The wood for distillation the latter it has been the practice to install wood burn- is measured (4), weighed (3), placed in retort buggies ers or incinerators to dispose of the mill waste, and (7), and distilled in the retort (21). The products hundreds of cords of wood are thus destroyed daily. of distillation are conducted from the retort through In the popular mind this waste is regarded as an eco- a bottom vapor outlet (2j), into the tar separator (26), nomic crime, and several efforts have been made to thence into the condenser (29), and finally the gases establish a wood distillation industry in the Northwest, are stored in the gas holder (14)~where they are sampled all of which have been commercial failures. and measured and finally pass to the furnace (18) for With a view to giving some assistance in solving combustion. For the estimation of the liquid products, this problem the University of Washington cooperated the distillate is pumped (39) from the pyroligneous for some time with the Bureau of Plant Industry of the acid tank (30) into a feed tank (38), from whence it United States Department of Agriculture in land clear - flows by gravity into a copper still (36) heated by ing studies and at the present time is in cooperation steam coils. The resulting distillate is separated (40) with the United States Forest Service in certain yield into light oil and crude wood vinegar (containing studies of distillation products from Eoth Douglas acetic acid, methyl alcohol, acetone, etc.) and stored fir stumps and the waste wood of sawmills operating in tanks for sampling. in the western part of the State of Washington. After The main interest centers, however, in the design some years of experience with this problem, both from of the retort. For experimental purposes a capacity a theoretical standpoint and from practical participa- of one-half cord was determined upon, which required tion in the industry, it appeared to the senior author dimensions approximately 18 feet I inch long. The of this paper that the failure of the commercial plants shell of the retort is 4 feet I inch wide and 3 feet 2 could, in each case, be traced to inferior and unusual inches high, made of one-fourth‘ inch steel and is methods of operation rather than to inferior products covered on the outside to a thickness of two inches with and lack of market as usually asserted. After personal standard heat insulation material. At one end a visitation of the principal distillation plants in the furnace is provided, the heat from which is conducted 93 6 THE JOURNAL OF IiliDL'STRIAL AND ENGINEERING CHEMISTRY 1'01. 5, NO. II through- four iron flues of five inches diameter. These a tight- fit. The door is shut tightly by means of four flues extend lengthwise within the retort as shown in cast iron eccentric clamps which act on two steel bars extending across the outer // surface of the door. The outlet for the prod- ucts of distillation is at the 5 bottom of the retort, Plate 4, which is sloped so that the opening constitutes the lowest portion'of the inner surface of the retort. The liquid and gaseous products are thus conducted from the retort through the outlet into the tar separator, which is air-cooled. The por- tions not condensing con- tinue to the top of the sepa- rator into the water-cooled condenser, Plate j. The dis- tillates are collected in a storage tank and the com- bustible gases are stored in a gas holder. PLATE1 The noticeable features 1. Railway switch. 18. Furnace. 34. Back-fire traps. 2. Charcoal yard. 19. Flue bypass. 35. Gas tar tank. in the design of the retort 3. Platform scales. 20. Stack. 36. Refining still. above described are: (I) the 4. Cord measure. 21. Retort. 37. Condenser. method of internal heating 5. Wood yard. 22. Heat insulation. 38. Distillate feed tank. 6. Retort buggy track. 23. Retort door. 39. Pump. by means of flues located 7. Retort buggies. 24. Door clamps. 40. Oil separator. entirely within the main 8. Charcoal chute. 25. Bottom vapor outlet. 41. Oil receiver. 9. Wood chute. 26. Tar separator. 42. Crude alcohol tank. shell; and (2) the drawing off 10. Retort buggy platform. 27. Separator tar tank. 43. Work table. of vapors from the bottom 11. Retort door platform. 28. Pipe to condenser. 44. Transformer and switch. of the retort. 12. Retort running board. 29. Condenser. 45. Sewage basin. 13. Steps. 30. Pyroligneous acid tank. 46. Still tar tank. The advantages of in- 14. Gas storage tank. 31. Gas booster. 47. Tar tanks. I ternal firing over the custom- 15. Firing platform. 32. Electric motor. 48. Crude wood vinegar tanks ary method of external heat- 16. Gas pipe to furnace. 33. Gas vent to air. 49. Building. 17. Gas pipe to tank. ing are considered to consist largely in economy of fuel Plates 2 and 3, terminating in return bends at the and control of temperature. By thorough insulation back end of the retort. From thence they extend of the retort shell, radiation losses from the shell are to the front end of the retort where they enter a smoke minimized, the temperature of the stack gases is more chamber, which in turn opens into the stack. The nearly that of the retort interior, the uniform distri- course of the heated gases of combustion is shown by bution of heat prevents local overheating, and the re- the arrows in Plate 2. tort suffers less depreciation due to unequal strains The wood for distillation is piled vertically in three from high temperatures than in the case of retorts retort buggies with sides made of steel screening. The exposed to the direct scaling and buckling action of heat. buggies operate on steel rails which contain a removable A number of considerations determined the selection 0.. L-^ Cdl c r- a 1 i -4 PLATE2 section at the retort door, thus forming a continuous of a bottom vapor outlet. In the distillation of the railway from the fore end of the retort to the wood coniferous woods it has been the writers' experience yard and charcoal pile.