Nov., 1gr3
T H E J O U R N A L O F I - V D U S T R I A L A N D E N G I N E E RI .VG C H E M I S T R Y
Acknowledgments
are
due
Assistant
Professor
G. F. Lipscomb for his careful oversight of the work of the students; to the students themselves a n d t o Mr. E. L. Hutchins for furnishing us with materials a n d for t h e use of his experiments a n d results. CONCLUSIOXS
I. From experiments conducted in this laboratory, it has been shown t h a t when cyanamid is mixed with acid phosphate in the ratio of one part of the former t o 6.2j or 8.33 or even 9.8 of t h e latter, there is, on standing, a gradual increase of the insoluble a n d consequent decrease of t h e available phosphoric acid in the mixture, a n d t h a t this is true whether the mixture consists simply of the acid phosphate and cyanamid, or whether ammoniates a n d potash salts are also present. 11. T h e experience of a t least three manufacturers working on a factory scale has shown t h a t there is a decrease of t h e available phosphoric acid when calcium cyanamid a n d acid phosphate are used in mixed fertilizers in the ratio of one part of t h e former t o 6 . 2 5 or 8.33 of the latter, thus confirming our own work done on a small scale.
I
935
111. The results of our fertilizer inspection analysis this past season point t o the same fact; i. e., t h a t there is danger of falling off in the available phosphoric acid when calcium cyanamid a n d acid phosphate are used together as ingredients of a mixed fertilizer. IT-. T h e results of all these experiments indicate t h a t the time element has a n important influence in determining the increase of insoluble phosphoric acid, a n d must be considered in addition t o the elements of temperature a n d the alkalinity of the cyanamid. T-. I t appears from the facts given in this paper, t h a t , though it may be said t h a t the effect of mixing cyanamid with acid phosphate will not injure t h e fertilizer from the farmer’s standpoint, the manufacturer must exercise some care as t o the amount of the cyanamid used in a mixture, else his mixture may, upon inspection a n d analysis, be found deficient in available phosphoric acid. CHBMICAL DEPARTYENT CLEMSON AGRICULTURAL COLLEGE SOUTH CAROLINA
LABORATORY AND PLANT
I
United States by both of us, we selected the type of plant described in this article as most nearly applicable B y H. K. EBNBON AND MARCDARRIN t o 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 S o r t h - by the United States Forest Service and the University west has recently attracted much attention. The of Washington a n d is now in operation. In this article interest lies partly in the necessity of clearing the only t h e design of the plant will be described since logged off or “cut over” lands which now number the results obtained will be t h e subject of later publicaover three million acres in the State of Washington tions by the Forest Service. alone. I n a more popular sense, t h e interest, however, The general layout of the plant is indicated b y the centers about the waste wood of t h e sawmills. In legend descriptive of Plate I. The wood for distillation t h e latter it has been t h e practice t o install wood burn- is measured ( 4 ) , weighed ( 3 ) , placed in retort buggies ers or incinerators t o dispose of t h e mill waste, a n d ( 7 ) , and distilled in t h e retort (21). The products hundreds of cords of wood are t h u s destroyed daily. of distillation are conducted from the retort through I n t h e popular mind this waste is regarded as a n eco- a bottom vapor outlet ( 2 j ) , into the tar separator (26), nomic crime, a n d several efforts have been made to thence into t h e condenser ( 2 9 ) , a n d finally the gases establish a wood distillation industry in t h e Northwest, are stored in t h e gas holder ( 1 4 )where ~ they are sampled all of which have been commercial failures. a n d measured a n d finally pass t o the furnace (18) for With a view t o 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 t a n k (30) into a feed t a n k (38), from whence i t United States Department of Agriculture in land clear - flows by gravity into a copper still (36) heated b y ing studies a n d a t 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 a n d crude wood vinegar (containing studies of distillation products from Eoth Douglas acetic acid, methyl alcohol, acetone, etc.) and stored fir s t u m p s a n d 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 t h e design some years of experience with this problem, both from of the retort. For experimental purposes a capacity a theoretical standpoint a n d from practical participa- of one-half cord was determined upon, which required tion in t h e industry, it appeared t o t h e senior author dimensions approximately 18 feet I inch long. T h e of this paper t h a t t h e failure of the commercial plants shell of the retort is 4 feet I inch wide a n d 3 feet 2 could, in each case, be traced t o inferior a n d unusual inches high, made of one-fourth‘ inch steel and is methods of operation rather t h a n to inferior products covered on the outside t o a thickness of two inches with a n d lack of market as usually asserted. After personal standard heat insulation material. At one end a visitation of t h e principal distillation plants in t h e furnace is provided, the heat from which is conducted THE DESIGN OF AN EXPERIMENTAL WOOD DISTILLATION PLANT
T H E J O U R N A L O F IiliDL'STRIAL A N D E N G I N E E R I N G C H E M I S T R Y
93 6
through - four iron flues of five inches diameter. These flues extend lengthwise within the retort as shown in //
5
1 . Railway switch. 2. Charcoal yard. 3. Platform scales. 4. Cord measure. 5 . Wood yard. 6. Retort buggy track. 7 . Retort buggies. 8. Charcoal chute. 9. Wood chute. 10. Retort buggy platform. 11. Retort door platform. 12. Retort running board. 13. Steps. 14. Gas storage tank. 15. Firing platform. 16. Gas pipe t o furnace. 17. Gas pipe to tank.
PLATE1 Furnace. Flue bypass. Stack. Retort. Heat insulation. Retort door. Door clamps. Bottom vapor outlet. Tar separator. Separator tar tank. Pipe to condenser. Condenser. Pyroligneous acid tank. 31. Gas booster. 32. Electric motor. 33. Gas vent to air.
18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.
34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49.
Plates 2 a n d 3, terminating in return bends a t t h e back end of the retort. From thence they extend t o t h e front end of t h e retort where they enter a smoke chamber, which in t u r n opens into t h e stack. T h e course of the heated gases of combustion is shown by t h e arrows in Plate 2 . T h e wood for distillation is piled vertically in three retort buggies with sides made of steel screening. The buggies operate on steel rails which contain a removable 0 . . L-^ Cdl
1'01. 5 , NO. I I
a tight - fit. T h e door is shut tightly b y means of four cast iron eccentric clamps which act on two steel bars extending across the outer surface of the door. The outlet for t h e products of distillation is a t the bottom of the retort, Plate 4, which is sloped so t h a t t h e opening constitutes t h e 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 t a r separator, which is air-cooled. The portions not condensing continue t o the top of the separator into the water-cooled condenser, Plate j. The distillates are collected in a storage t a n k a n d the combustible gases are stored in a gas holder. The noticeable features Back-fire traps. in the design of the retort Gas tar tank. Refining still. above described are: ( I ) the Condenser. method of internal heating Distillate feed tank. by means of flues located Pump. Oil separator. entirely within the m a i n Oil receiver. shell; a n d ( 2 ) the drawing off Crude alcohol tank. of vapors from the bottom Work table. Transformer and switch. of the retort. Sewage basin. T h e advantages of inStill tar tank. I Tar tanks. ternal firing over the customCrude wood vinegar tanks ary method of external heatBuilding. ing are considered to consist largely in economy of fuel a n d control of temperature. By thorough insulation of the retort shell, radiation losses from the shell are minimized, t h e temperature of t h e stack gases is more nearly t h a t of the retort interior, the uniform distribution of heat prevents local overheating, a n d the retort suffers less depreciation due to unequal strains from high temperatures t h a n in t h e case of retorts exposed t o the direct scaling and buckling action of heat. A number of considerations determined the selection
c
r-a 1
i
-4
PLATE2
section a t the retort door, thus forming a continuous railway from the fore end of t h e retort to the wood yard a n d charcoal pile. T h e retort door a n d door seat are made of cast steel a n d are carefully planed a n d milled so as t o insure
of a bottom vapor outlet. I n the distillation of t h e coniferous woods i t has been the writers' experience t h a t coke deposits usually exist on charcoal drawn from t h e bottom of the retorts, It is generally assumed t h a t such coke is the product of secondary distillation
yr0 V . , I 9 I 3
T H E J O P R S A L O F I N D C S T R I A L A iVD E ,I'GINE E RI N G C H E M I S T R Y
of t a r . I n other words, when t a r is in t h e process of formation from wood, i t forms a high boiling volatile
93 7
planation has been verified b y actual operation, coke being found on t h e charcoal only where oleoresin or "pitch" had previously existed in t h e n*ood. For t h e purpose of determining t h e size of flues t h e t h e following assumptions were made: (1) (2) (3) (4)
,
