INDUSTRIAL AND ENGINEERING CHEMISTRY
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eliminated by substituting inertia- and lag-free electronic methods. No elaborate mechanical construction is involved, as standard parts are used throughout. It should be of general utility in all investigations involving very slow or very rapid changes of weight or in the study of phenomena which can be followed indirectly by a change of weight. The complete instrument costs about $500, excluding labor.
VOL 10, NO. 8
Literature Cited (1) Binnington and Geddes, IND. ENG.CHEM.,Anal. Ed., 8 , 7 6 (1936) ( 2 ) Coutts, J. R. H., Crowther, E. M., Keen, B. A , , and Oden, Sven Proc. Roy. SOC.(London), A106, 33 (1924). (3) Muller, R. H., and Garman, R. L., Mikrochemie, 21, 302 (1937). (4) Oden, T ~FaradaU ~ Sot,, ~ 17, ~ 327.(1922). ( 5 ) Svedberg and Rlnde, J. Am. Chem. SOC.. 45. 943 (1923). RECEIVED March 12, 1938
Antifoaming Device for Use in Concentration of Noninflammable Liquors E. A. GASTROCK
ALIiD
J. DAVID R E I D , U. S. A g r i c u l t u r a l B y - p r o d u c t s Laboratory, I o w a S t a t e College, i m e s , Iowa
T
HE prevention of foaming is generally accomplished by
the addition of a n antifoaming agent such as kerosene, capryl alcohol, etc., or by the use of mechanical devices, among which are a n air jet ( 2 , 3, 4,6, 7 ) , a special still-head ( I ) , and a paddle Theel (6, 8). The investigation of some alkaline pulping liquors, in this laboratory, necessitated their concentration by distillation. These liquors foamed profusely. The commonly used antifoaming agents were unsatkfactory because they were inefficient, their presence interfered with subsequent chemical examination of the residue, and the volatile agents n-ere lost by distillation. Fanto ( 2 ) used a current of cool inert gas to break the bubbles b y condensation of the enclosed vapor, but stated t h a t sometimes the liquid was carried over mechanically, so that it was necessary to redistill. Certain evaporators of commercial size control foaming liy
n
h
RESISTANCE UNIT
H
continuing the heating surfaces above the liquor level, thus destroying the foam by contacting and vaporizing the liquid film ( 9 ) . An itnprovement on this action is niade use of in the apparat’us shown in Figure 1, whereby the heat from the coil, A , disrupts the foam bubbles without contact and allows the distillation to proceed a t a rapid rate without carry-over.
Apparatus and Operation embled apparatus is shown in Figure 1. The toanibreaking coil, A , consists of 88 em. of S o . 22 gage (0.64-mm.) Sichrome wire, in the form of a helix, fastened to No. l ( i gage (1.3-mm.) copper wire leads, B and B’. The leads pass through the stopper, D. Coil 9 must be placed low enough to avoid undue heating of the flask wall above it. The power is 110-volt alternating current, suitably controlled by a resistance unit or transformer, The resistance unit used is made by connecting two 500-watt heating coils, C and C‘, mounted in porcelain sockets, with witches, 3’ and S‘, so that one or both may be used. Switch S’ controls the unit. The temperature of coil A is higher when witch S is closed than when it is open. The binding posts, E and E‘, are convenient for connecting the copper leads, B and H’. Material for the unit costs about one dollar. Flask F should have a capacity of 2 liters or more, providing sufficient room to place the hot wire, A , at least 4 em. from the glass above it. The liquid should be heated t,o incipient boiling Before the current is turned on. Ordinarily, only coil C is used as the wire, A , need not be at red heat. However, the wire should be hot enough so that the bubbles burst at least 1 em. from the \Tire, in order to prevent the mire from becoming coated by material which would t,hen dry and burn. The temperature of wire A may be varied by changing its lengt,lior gage, or by changing the resistance of the coils, C and C’. Condensate from tube T should not drop on the hot \Tire. Once started, the distillation proceeds at a rapid rate without further attention.
Discussion and Conclusions The antifoaming device described is limited in use to the distillation of noninflammable substances. It has proved successful in the laboratory distillation and concentration of alkaline pulping liquors that foam excessively and should prove useful in the distillation of many aqueous foam-producing solutions. There appears to be no reason why it should not be applicable to large-scale apparatus.
Literature Cited (1) Eddy, C. W ,ISD. ENG.CHEY.,Anal. Ed., 4, 1YS-9 i l Y 3 2 ) . ( 2 ) Fanto, R. Z., Angew. Chem., 20, 1 2 3 3 4 (1907). (3) Friedrichs, F., J . SOC.Glass Tech., 12, 306 (1928) (4) Gerritz, H . IT., ISD. ENG.CHEY.,Anal. Ed., 8, 75 (1936). ( 5 ) Jantzen, E., and Schmalfuss, H., Chern. F n b r i k , 1934, 61-3. (6) Klanhardt, Chern.-Ztg., 46, 493 (1922).
(7) Kummer, R., Chern. tech. Rundschuu, 44, 14 (1929). (8) Miller, R. W.,Can. Chem. X e t . . 14, 19-21 (1930). (9) Walker, IT. H . , Lewis, IT. K., and hlcAdams, ’w. H., “Principles of Chemical Engineering,” 2nd ed., p. 400, Kew York, McGrawHill Book Co., 1927.
FIGURE 1.
DI.lGR.I\I
O F APPARATUS
R E C E I V E D>lay 26, 1938.
