September 1952
INDUSTRIAL AND ENGINEERING CHEMISTRY
It is hoped that within the next year it will be possible t o undertake pilot plant trials of this process. Meanwhile work on the fermentation method and also on some of the more fundamental aspects of the problem oi citric acid formation are being continued in the laboratory. Acknowledgment
The authors wish t o acknowledge the technical assistance of Joseph Langevin and James Slobodian. literature Cited (1) Can. Chem. Process I d s . , 35, 266 (1951). (2) Chem. Eng. News, 28, 3982 (Nov. 13, 1950). (3) Chem. Inds., 68, 20 (1951).
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(4) Kolmer, J. A,, and Boerner, E., “Approved Laboratory Technic,” New York,Appleton-Century Co., 1945. (5) Moyer, A. J., Proc. SOC. Am. Bact., 51st Gen. Meeting, 1951. (6) National Research Council, Can., Div. Applied Biology, Quart. Rept., 3, No. 2 (1951). (7) Perlman, D., Econ. Botany, 3, 369 (1949). (8) Perquin, L. H. C., thesis, Delft, 1938. (9) Saffran, M., and Denstedt, 0. F., J . Bhl. Chhem., 175, 849 (1948).
(IO) Schweiger, L. B., and Snell, R. L. (to Miles Laboratories, Inc.), U. S. Patent 2,476,159 (July 12, 1949). (11) Shu, P., and Johnson, M. J., IND.ENG.CHEM.,40, 1202 (1948). (12) Snell, R. L,and Schweiger, L. B. (to Miles Laboratories, Inc.), U.8. Patent 2,492,667 (Dee. 27, 1949). (13) Woodward, J. C,, Snell, R. L., and Nickols, R. S., Ibid., 2,492,673 (Dec. 27, 1949). RQCEIVEDfor review November 19, 1951. ACCEPTED April 24, 1952. Issued as Paper 139 on Usee of Plant Products and as N.R.C. 2774.
fngFnyring
Precision liquid Feeder
Ppocess development I
B. W. JONES, S. A. JONES, AND M. E. NEUWORTH Pittsburgh Consolidation Coal Co , Library, Pa.
F
E E D I N G of high melting organic compounds and viscous with a properly dimensioned cylinder and grooved piston, the 0 tarry fractions at low nonpulsating reproducible rates was an ring is squeezed, resulting in a hydraulic seal. 0 ring seals can essential requirement for quantitative investigation of specific be ueed for pressures up t o 3000 pounds per square inch. Howorganic reactions in this laboratory. In addition, continuous ever, operating pressures approaching this limit would require subfeeding of these materials was required in amounts up t o 500 stituting a steel cylinder. Steam jacketing of the cylinder permits grams against variable pressures and with a maximum error of the feeding of compounds which melt below 100’ C. Modi1%. A variety of liquid feeders has been fying the method of heating or substitutdescribed recently by Lundsted et al. (1) ing a different heating fluid would permit and Michaeli (9). Several are also availhandling - matorids having a much higher able commercially. However, none of the rqelting point. Feed rates from 0.8 to 13 PLUNGER a designs described would meet all these rem1. per minute can be obtained with the ’O-RING quirements. present design. The design of a feeder based on a motorDetails of the feeder are shown in Figdriven syringe was undertaken. A syringe ure 1. Feeding is effected by pushing the feeder is particularly well suited for the plunger through the cylinder a t a condelivery of a completely nonpulsating flow stant rate. The cylinder i? large enough to hold the entire charge t o be fed. of liquid independent of back pressure It is fabricated from precision-bore glass variations. Fabrication of a conventubing with an inside diameter tolertional syringe of the desired capacity from ance of *0.0002 inch. This tubing can be obtained from Fischer & Porter Co., either metal or glass was considered imHatboro, Pa. The connection between practical. Tolerances between the plunger the cylinder and a metal reaction sysCLUTCH and the syringe barrel cannot be made tem is made by means of a glass t o close enough t o assure a liquid seal where metal ball and socket joint or glass t o metal pipe connection. The plunger any appreciable back pressure is encounhas 8 groove in its periphery which tered. Development of a successful design carries an 0 ring gasket, assuring a liqwas accomplished by utilizing an “0” uid t,ight seal with the cylinder walls. It is equipped with a small drain cock ring-sealed metal piston in a precisionwhich permits drainage of the cylinder bore glass cylinder. An 0 ring is a round without disassembling the unit. This is cross section, perfectly circular rubber ring convenient for cleaning the feeder, particularlv when the cvlinder contains cormolded to extremelv close tolerances. It is rosive *chemicals. -b rings are availgenerally fitted into a rectangular, maFigure 1. Schematic Diagram able in a sufficient variety of matechined groove. When used in conjunction of Feeder rials t o handle most liquids. The authors
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
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have used neoprene, silicone, and Butyl rubber 0 rings. They can be supplied by Precision Rubber Products Corp., Dayton, Ohio. A constant speed motor oi' 1 r.p.m. turns the driving screw through suitable gears. In the present design, a flexo-actio11 motor manufactured by Merkle Korff Gear Co., Chicago, Ill., has been used. The clutch, supporting the plunger connecting rod, is equipped with threaded dogs to engage the driving screw. It is kept in proper alignment by two guide rods which are bolted
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600
GRAMS DEL I VERED
Figure 2.
Calibration of Feeder
to the lower and upper plates of the driving mechanism. The plates also serve t o hold the bearings for the driving screw. The clutch can be disengaged from the driving screw by simply turning the knurled engaging knob. A small pointer attached t o the clutch passes over an accurately graduated metric scale fastened to the mounting board holding the feeder. It is particularly handy for calculating the rate of travel of the plunger during feeding. Four sets of gears with common centers have becn used with the present design. These will allow seven feed rates, from 0.8 to 12.8 ml. per minute. A wider range of feed rates can be attained by substituting a motor of different revolutions per minute or a oylirider of altered internal diameter. The accuracy of the feeder is well demonstrated by the rcsults
Engk;
rin g
Vol. 44, No. 9
of the following experiments shown graphically in Figure 2. One calibrat,ion was made with a low melting organic compound held at 100" C. by supplying steam t o the remrvoir jacket. Gear ratios were selected t o give a rate of 1.5 r.p.1~1.t o the driving screw. The amount delivered over each 10-minute period was weighed on a beam balance. Over 490 grams were deliverod at an average rate of 4.81 grams per minute. The maximum devitttion from this average was 0.7'3,. In a sccond experiment, a. second calibration was madc with a liquid organic compound at room t,emperature. Gear ratios were used to give a rate of 0 . 5 r.p.m. to Lhe driving screw. Weighings were made L ~ Rin the first case. Total delivery was 536.7 grams with an average feed rate of 1.73 grams per minut,c. The maximum deviation from this average was 1.1%. If 20 mm. from each end of the cylinder arc not included in the calibration, the maximum deviation from the average is 0.60/,. Slight distortion near the ling seals between the cylinder and jacket i s responsible for this variation in rate. A stainless steel cylinder was substituted for the glass cyliutlcr for pumping high melting point coal t,ar pitch requiring temperatures of from 150" to 200' C. The sanie accuracy in pumping rate was attained by machining and polishing the steel cylinder to comparable tolerances. The cylinder was heated electrically with an air space between the heat,er and cylindeT to prevent localized overheating.
Acknowledgment The author8 wish to acknowledge the help of George Driesen of the machine shop in building the feeder and designing the driving clutch.
literature Cited (1) Lundsted, L. G . , Ash, A. B., and Koslin, ti.L., Anal. Chem., 22, 626 (1950). (2) Miohaeli, I., Chembtiu and Industry, 1951, No. 8 , 123. RECBIVW for review September 27, 1951.
ACCBPTEDApril 18, 1932.
Improving the Density and Strength I Briquets
Process development I
T H E O D O R E BREITMAYER'
AND
F R A N K B. W E S T 2
University of Washington, Seuftle, Wash.
ANY investigators have attempted t o briquet charcoal t o produce a satisfactory substitute for domestic or industrial fuel, metallurgical coke, or carbon electrodes. Such studies have been of particular interest t o regions having abundant wood wastes but little coal, gas, or petroleum. The principal advantages of charcoal over coal are its low ash, sulfur, and phow phoivs contents. Its principal disadvantages are its low density a s d crushing strength which make it difficult to store, t o transport, to handle, and to use. To be suitable for mctallurgicitl coke or carbon electrodes, charcoal moldings require high strength and density and low volatile matter content. The density and strength can be improved by briquetting with binders such as 1 Present
* 1'1 esont
addrese, Crown Zellerbaoh Corp., Camas, Wash. address, Shell Development Co., Emeryville, Calif.
starch, and some such briquets have been uscd in this country &E( domestic fuel (8). The use of by-product wood tar from the production of the charcoal as the binder for briquetting the charcoal haR been reported by numerous investigators (W, 5-7, 9, IO). The tar htm often been diluted with a solvent for better application. The resulting briquets have generally been baked a t temperatures above 300' C . to produce strong briquets. Beuschlein and coworlcers in this laboratory (2, 6) have also investigated the a h r p t i o n of the heavier tar components directly from the retort gtm onto the partially cooled charcoal, thus eliminating the steps of tar recovery, preparation, and mixing with the charcoal. They have also studied the manufacture of briquets by extrusion. The purpose of the present study was t o investigate two methods for further increasing the strength and density of char-
