OCTOBER,1938
INDUSTRIAL AND ENGINEER1,JNG CHEMISTRY
B y means of the ultracentrifuge the above type of analysis could be carried out in much greater detail. Particularly important would be information on the nonuniformity, with respect t o molecular weight of cellulosic materials, on molecular weights of a given material i n a variety of solvents, a n d on sedimentation-velocity relations. However, t h e d a t a along these lines are not yet sufficient for public presentation. However, t h e present status of t h e subject seems t o justify the use of intrinsic viscosity measurements for characterizing t h e degree of degradation of cellulosic materials and estimating t h e average (weight-average) degree of polymerization by means of t h e constants relating it t o intrinsic viscosity, which have been determined with t h e ultracentrifuge.
Literature Cited (1) Carter, S. R . , and Record, B. R., Chemistry and Industry, 1936, 218. (2) Compton, J., paper presented before Div. of Cellulose Chemistry ab 94th Meeting of A. C. S., Rochester, K. Y . , Sept. 6 to 10, 1937. (3) Dobry, A,, Bull. SOC. chim., [5] 2, 1882 (1935). (4) Dobry, A., J. chim. phys., 31, 568 (1934). (5) Ibid., 32, 50 (1935).
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(6) Farr, W. K., paper presented before Div. of Cellulose Chemistry a t 92nd Meeting of A. C. S., Pittsburgh, Pa., Sept. 7 to 11, 1936. (7) Haworth, W. N., Monatsh., 69, 314 (1936). (8) Hess, Kurt, Angew. Chem., 49, 841 (1936). (9) Hess, Kurt, 25 Jahre Kaiser Wilhelm Gesellschaft zur Forderung der Wissenschaften,Band 11, p. 172, 1936. (10) Kraemer, E. O., papers presented before Philadelphia Section, A. C. S., Dec., 1934, and Johns Hopkins Univ. Summer Conferences, Gibson Island, Md., 1935. (11) Kraemer, E. O., and Lansing, W. D., J. Phys. Chem., 39, 153 (1935). (12) Lansing, W. D., and Kraemer, E. O., J . Am. Chem. SOC.,57, 1369 (193.5). (13) Ibid., 58,-1471 (1936). (14) McBain, J. W., and Laing-McBain, M. E., Ibid., 59, 342 (1937). (15) Staudinaer, H., Anaew. Chem.. 49, 574 (1936): Melliand Teztilber., 18, 53 (i937). (16) Tiselius, A., 2.physik. Chem., 124, 449 (1926). (17) Ulinann, Max, “Molekulegrossen-Bestimmungen hochpolymerer Naturstoffe,” Dresden, Theodor Steinkopff, 1936. RECEIYED March 12, 1938. Presented before the Division of Cellulose Chemistry a t the 93rd Meeting of the American Chemical Society, April 12 to 15, 1937. Contribution 179 from the Experimental Station of E. I. d u Pont de Nemours & Company, Inc.
CORRESPONDENCE Distillery By-Products That “they use less steam, and/or fuel, labor, and water” is AND ENGINEERING SIR: The June, 1938, issue of INDUSTRIAL open to question. Figure 1 is a diagram of an apparatus from a CHEMISTRY contains a description of “Distillery By-Products” by patent issued t o me in 1910 (2). This illustration gives a better Lloyd Cooley (3) and gives a flow sheet of the Hiram Walker & understanding of the processes than those published by Cooley. Sons plant a t Peoria, Ill. None of this equipment was in the disThe beer still, 1, is omitted in Cooley’s paper; the still shown here tillery on the day before its opening, July 4, 1934, except the conhas a superheater, 36, that receives part of the slop and evaporates veyor mixer and the rotary steam dryers, nor was it then conit by steam coils, 39. The tubes boil the slop, and the water contemplated. Stricter laws compelled the adoption of the process densed in the process returns to the steam boilers as pure distilled of saving the soluble solids. Cooley’s historical review (3) omits water. Practice shows that about 20 pounds of steam condense some of the earlier work because this author has been engaged in to water in distilling a hundred pounds of “beer.” Keeping this the work only since the repeal of prohibition. out of the slop by use of the superheater means a 20 per cent There is an idea among the newer generation that little chemisaving in evaporation and in fuel by this system. The screens cal work had been done before prohibition in the arts of distilling illustrated by Cooley and by 23 of my drawing have been imand utilizing the by-products ( 1 ) . Feeding slop t o cattle had proved by arranging them double and in tandem. The coarse been practiced for many generations and was stopped only after grain falls on the lower screen, and the filtrate from the upper legislation against it was passed in many states, for the waste screen passes again through the grains on the lower screen, thus from the cattle barns was more polluting than the hot slop. It producing a thin slop nearly equal to that from the centrifugals. became illegal t o feed milch cows with slop because of the resultAs described, this centrifugal process is not attractive on acing unsanitary condition of the barns. No objection t o using count of the expense of installation, the driving power required, dried solids as a feed stuff was ever made. and the labor, although it yields a product with only 20 per cent Screening and pressing the grains for slop were developed a t the solids and 80 per cent water. Perhaps these centrifugals might be end of the last century. Patents issued t o Hinken (4) for a filter of the milk type and produce a sludge cream that would conpress specially adapted for slop filtration and t o Turney (6) for a tain about the same percentage of solids. The presses menrotary dryer heated by inside steam tubes gave practical means tioned are quite old and have been successful in breweries for for saving the insoluble solids in the slop. Saving the soluble solids began in 1905, following the work of squeezing the brewers’ grains fairly dry. The roller press, 24, is the most popular a t present. Cooley mentions returning the the great pioneer, Otto Behr, who experimented with cornstarch “screen eauent.” This is the old process of “slopping back.” and glucose and made “gluten meal,” etc. This was done mostly to prevent pollution of the Mississippi tributaries, as a result of It has the advantage of furnishing the yeast with nitrogen, laws on the subject. During prohibition the industry died and organic acids, and potash. Since yeast is a vegetable, it needs fertilizers (as Pasteur found out) ; Cooley showed that it is also was revived with repeal. As Cooley states, the prewar slop saving was “in principle much like the methods used today” except advantageous when the slop is slopped back, since that means a that the later units “have greater capacity.” saving in evaporation. This is most important when all solids
INDUSTRIAL AND ENGXNEERING CHEMISTRY
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It is hoped that this more detailed description of what is possible with this process of by-product recovery and elimination of nuisances will be profitable to manufacturers in other lines who have problems that can be solved in the same way.
Literature Cited (1) (2) (3) (4)
Chute, H. O., Trans. Am. Inst. Chem. Engrs., 33,93 (1937). Chute, H. O . , U. S. Patent 963,275 (July 5, 1910). Cooley, Lloyd, IND.ENQ.CHEM.,30, 615 (1938). Hinken, J. H., U. S. Patent 607,929 (July 26, 1898), reissue 11,772
(Sept. 19, 1899). (6) Turney, J. E., U. 5. Patent 581,794 (May, 4, 1897). 50 EAST41ST STREET N s w Y O R XN. , Y. June 6, 1938
FIGURE 1
are to be saved. The multiple-effect evaporators sketched in Cooley’s paper compare with the A , B, C effects here illustrated, but it is probably preferable t o have 2 third effects with valves so that either one may be taken off alternately and used as the “cast-iron finishing pan,” while the other evaporates the slop to a point where it is ready for the finishing under higher steam pressure. It is stated that if the (screened) liquid could be dumped into the sewer, it would hold half the solids and save most evaporation costs. In prewar days the grains gave 9 pounds of cattle feed, and the complete saving was 18 pounds from Bourbon mashes. Cooley claims only 15 pounds. The “ten panels with buttons” reveal the modern tendency to operate plants with buttons; in prewar days they were operated with brains.
H. 0. CHUTE
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SIR: H. 0. Chute has furnished a welcome and informative elaboration of my recent article on “Distillery By-Products.” However, his second sentence, “except the conveyor mixer and the rotary steam dryers,” should have had added t o it, “and screens and rotary presses.” Installation of evaporators had been seriously contemplated prior to the building of the distillery, but the cost of installing and operating them had appeared to outweigh probable profits. Permission was requested of the authorities to delay the installation of the evaporators until a t least a year’s investigation could be made of better methods. This permission was denied. Because the recovery units are larger than former units, the labor cost is lower. The over-all cost for steam per ton of product is lower than formerly, because of the fact that sirup is sent to the dryers a t double the customary concentration. Fair comparisons of yield are difficultto make because of variations in the fermentable contents of the grain. A yield of 15 pounds of dried feed per bushel of grain mashed would be very satisfactory if the yield of alcohol were also good. A yield of 19 pounds per bushel might imply a low starch content or a poor yield of alcohol, leaving more solid matter t o be recovered in the feed. A closed heater for the beer still would save steam in the evaporating process. The subject was considered seriously b y the engineers a t the time the distillery was built, but in view of the projected supply of low-cost exhaust steam, the large heaters needed for the size of the beer stills, and the probable operating troubles, it was deemed wise to omit closed beer heaters or vaporizers a t that time. In regard to Chute’s remarks about operating plants “with buttons. .brains,” it is of interest to note that only graduate chemical engineers were employed to operate the cookers, stills, and evaporators. The brains had to see beyond the buttons.
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15 ENOSPLACE JERSEYCITY, N. J.
July 27, 1938
LLOYDC. COOLBY
