Chemical Engineers at Chicago
N
ATIONAL defense and the
all-out effort of t h e chemical industries was the keynote of t h e 33rd annual / meeting of the American Institute of Chemical Engineers at / Chicago, M a y 19 t o 21. Focal point of the discussions on the war efforts was a symposium, presided over by Gustav Egloff, Universal Oil Products Co., in \ which experts from various fields \ told of t h e effort and status of \ . defense production in their in\ dustries. y T h o s e w h o spoke in addition to D r . Egloff were L. B . Grant, D o w Chemical C o . ; R. E . Wilson, P a n American Petroleum and Transport Co.; C. P. F . C . F r a r y , president, a n d S. L. Tyler, secretary D a v i s substituting for W. S. Landis, American Cyanamid per pound in 1941. As much improveCo.; R. J. Moore, Bakélite Corp.; ment is shown in mechanical and corroand Major J. F. Battley of the Selecsion characteristics of t h e many alloys. t i v e Service System. Preliminary magnesium castings were A n almost record attendance of 499 weak and unable t o withstand even as heard D r . Egloff s e t the tempo of t h e dislittle as six months' exposure t o sea water. cussion w h e n in his introductory remarks T o d a y alloys have been developed which he said, "Our national defense program is are used in supporting beams, and there rapidly turning into a n international deis no noticeable corrosion to samples fense", and "Whether the war lasts 5 which have been given sea water exposure years, 10, or 40 years, the end will be the tests of longer than six months. Wright, same—that is, t h e defeat of the totaliRanger, and Allison airplane motors and tarian ideology of government so t h a t we the wheels for army bombers are made m a y continue i n t h e democratic life which from magnesium alloy castings. A n averhas been so abundant t o all of us." Mr. age of 1000 pounds of magnesium is used Grant traced t h e development of magneon each plane. sium alloys a n d outlined their part in the defense efforts. From a price of $1.80 "When Hitler developed highly mechper pound i n 1918, he said, research has anized war h e developed something right lowered magnesium prices t o 22 1/2 cents up our alley," commented Bernard
Barauch, according t o R. E. Wilson, w h o spoke next on petroleum and t h e war. Dr. Wilson gave m a n y interesting figures which tended t o bear out Barauch's statement. Twentyfive of our 27 army divisions are motorized; one year ago the army had 14,000 vehicles of all kinds, today i t h a s 75,000, and by late fall will have 286,000. Today we are producing 1,400 / military planes a month, and this will increase to 2,000 by summer. I n mechanized warfare fuel is important, and the vast supplies and superior gasolines of t h e United States are bound to play an important part. Fuels used in airplanes are of the highest type and were undreamed of years ago. With synthetic 100-octane gasoline and high-compression engines, less dead weight per horsepower i s needed—all tending t o faster planes. Today a plane with a speed greater by only 25 miles per hour can wrest control of the air from the slower airplane. In t h e United States today, D r . Wilson continued, we have enough undeveloped oil t o enable us to increase production 30 per cent for two years without straining. T h e United States controls 63 per cent of t h e world's output of petroleum. T h e only stringency m a y come from tanker capacity, according to D r . Wilson, who said although American flag tanker tonnage is 20 times what it w a s in the last war, tanker transportation facilities t o the East coast are not adequate to take care of any sharp
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637
638 increase i n demand or loss of tankers, ex cept by curtailment of civilian supplies. "What is needed more than newer and fancier gadgets is production, production in great quantity", said C. P. Davis, speaking for W. S. Landis, "and a thou sand tons of bombs of the good old-fash ioned variety dropped on an enemy city tomorrow would probably have more effect toward a quick solution of this particular war than all the contributions of our re search laboratories for several years." Commenting on the ability of chemical industry in the United States t o meet de fense needs, Dr. Landis in his paper stated that it i s prepared t o meet any demand placed upon it, and that American indus try is as far advanced and as competent to cope with defense needs as any in the world. D r . Landis stated that the real problem however is economic, inasmuch as the plants now building are large and lo cated in a section of the country that has not attracted in any large way the com mercial chemical industry. Large produc ing units will be set up, many of them in isolated districts, new communities will come into being and will exert political pressure when the emergency is over to keep these plants in operation. "This", he said, "is arbitrary and uneconomical competition to an industry that has proved its ability to take care of all ordinary re quirements of our country and which has been founded on t h e principle of free economy and free competition." R. J. Moore told of the role plastics are playing in our armament program with particular emphasis o n fields of applica tion, limitation, and physical properties. Citing examples of plastics in defense work, h e said shock-resistant compounds are finding outlets in instrument cases for aircraft, fuse timers, electrical fittings, and in making gun stocks, in which case plastic stocks have replaced walnut stocks in Smith and Wesson sub-machine guns. Laminated and plywood products are of vast importance t o present day construc tion methods both in airplanes and the new motor torpedo boats. D r . Moore showed a plastics comparator which points o u t various plastic properties. The numbers indicate relative value starting with num ber one as best. The higher the number the poorer, relatively, is t h e material i n that particular property. At t h e banquet M a y 20, Thomas K . Sherwood, professor of chemical engineer ing a t Massachusetts Institute of Tech nology, was awarded the 1941 William H. Walker Medal for outstanding contribu tions t o chemical engineering literature. T h e award was presented b y Francis C . Frary, president of the institute, and C. C . Furnas, of Yale University and chairman of the award committee, cited five of Dr. Sherwood's papers on mass transfer a s being of exceptional merit t o the engineer ing profession. Dr. Sherwood joined t h e chemical engineering faculty of M. I. Τ. in 1930, where in addition t o his teaching duties he has carried on extensive research
NEWS
E D I T I O N
on gas absorption, extraction, and drying operations. Since 1933 he has been in charge of graduate students in chemical engineering. I n addition to the defense symposium, there were four technical sessions and vis its to 16 plants. Student awards were made at the business meeting May 19 for the best solution o f the annual student problem.
Abstracts of Technical Papers GRANULAR
SEPARATION
METHODS.
A. J. Barnebl, Swenson Evaporator Co., presented a comprehensive history of granular separation methods. For this unit operation Mr. Barnebl listed six dif ferent machines commonly used—the batch centrifugal, timed cycle centrifugal, continuous centrifugal, Dorrco filter, ro tary vacuum salt t y p e filter, and t o p feed filter—and in addition discussed a new feed for th.e top feed filter which h e said makes it possible t o control the density of the magma. The new feed consists of a hopper in which t h e granular material settles to a, maximum density. T o cause the magma to flow through the hopper t o the distributor plate, a given amount of liquid is forced into the settled material by means of injectors. The hopper m a y have more than, one outlet nozzle depending on the size of the filter and the amount of feed required. This method was said t o be successful with t o p feed filters because i t produces a uniform cake of high porosity and the high density of the magma pre vents darn leakage to material already dried and being scraped from the drum. ORGANIC ION EXCHANGERS.
T h e indus
trial application o f organic ion exchangers and their advantageous characteristics were discussed by F . K. Lindsay, National Aluminate Corp., who compared them with the natural and artificial zeolites used in water softening and described many actual operating installations in which organic exchangers were used. Organic ion exchangers a r e usually resins or con densation, products of the phenols and formaldeliyde. Resins with a sulfonic group appear t o be t h e most active and have t h e highest ion exchange. In the commercial development of the resins for industrial applications, extreme care must be shown to have the product chemically stable a n d water insoluble. Both cationic and anionic exchange is possible with the synthetic resins types. Through use of a regenerant consisting of a mixture of so dium salt and a n acid, organic cation ex changers can b e used to reduce or elimi nate the bicarbonate content of water and substitute sodium for the calcium, magne sium, o r chlorides present; i n effect, a hydrogen and sodium exchanger in the same b e d . Application is not limited to water conditioning. I n the sugar beet industry, inorganic ash is eliminated from the juice by passing it through a cationanion exchange plant. COLUMN HOLDUP.
A. P . Colburn and
R. F. Stearns examined t h e effect of col
Vol. 19, No. II umn holdup on batch distillation from a theoretical viewpoint and from experi mental procedure designed to test the theory. Conclusions from the theoretical study were that one effect of column hold up—to increase the spread between prod uct and still compositions during distilla tion—tends toward a sharper separation. This effect was thought to depend upon the holdup, still-charge ratio, and the rate of change of plate composition with the per cent take-off. When only a small amount of given constituent is present in the still, holdup will tend to a poorer separation because of the accumulation of the more volatile component in the col umn. In the experimental work, ethylene dichloride and toluene were used to study effects of varied reflux ratios and holdup. At constant reflux and varied holdup there was less separation with increased holdup. With constant holdup and var ied reflux there was little change in the sharpness of separation. SIMPLE COLUMNS FRACTIONATING M U L TICOMPONENT M I X T U R E S . R. L. Smith,
Universal Oil Products Co., has developed a rapid over-all method for the design of simple columns fractionating multicomponent mixtures. For solution the new method does not require composition, temperature, an assumed feed plate, or the number of plates to be known. T h e method involves the assumption of a feedplate temperature and is based on the rela tion of mole fractions of a component in the products t o its mole fraction in the feed plate liquid and in the vapor rising t o the plate above the feed. An average y / x or Κ value, which is the mole fraction ratio at equilibrium, is used as a constant for a given number of plates, and from a series of material balances a fractionating ratio is obtained, y tt +i/xo, which is the mole frac tion in vapor phase over the mole fraction of a component in total mixed phase. A stripping ratio is calculated as Xm/Xw·: x m is the mole fraction in liquid phase in the feed plate and X w mole fraction in reboiler. With these three—the average mole frac tion ratio, the stripping ratio, and the frac tionating ratio—if a number of plates and effective average temperature are known, the mole fractions i n the feed plate liquid and in the vapors rising from the feed plate can be calculated. For a certain feed there is one particular combination a t which t h e total number of plates in the column is less than any other combination, and b y the use of the above ratios t h e column is calculated for the combination of plates, above and below the feed, which gives the minimum number of total plates. This result is considered the correct de sign. AMINE
G A S PURIFICATION
PROCESS.
R. M. Reed and W . R . Wood, Girdler Corp., produced data on the amine gas purification process and design of gas ab sorption systems. This paper was a re view of progress in the field, and special attention was given to the correlation of theoretical studies and their application to
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NEWS
640 practical design. Amine gas purification systems are being used t o adsorb hydrogen sulfide or carbon dioxide from a gas stream and, as certain amines are strongly basic, they absorb acid gases readily. Regenera tion b y heating only is possible because amines possess the property of becoming practically nonalkaline at elevated tem peratures with the result that t h e amine sulfides and carbonates dissociate and are volatilized from the solutions. Flooding velocities in bubble and packed towers were found t o be predicted quite accu rately with Sherwood's correlation 1 from data of Uchida and Fujita. In one case a 27-inch diameter tower packed with 0.75inch Raschig rings had an actual flooding when t h e gas velocity was 0.64 foot per second while the calculated value was pre determined as 0.65 foot per second. LIQUID-LIQUID
EXTRACTION.
S.
B.
Row, J. H . Koffolt, and J . R. Withrow added n e w experimental data t o t h e literature of liquid-liquid extraction. E x perimental work was done on a 9-inch glass extraction column, using the system toluene-benzoic acid—water and various packing materials. The investigation brought out that high rates of flow of the continuous phase, water in this case, have a profound influence o n the over-all height of t h e transfer unit. This effect was minimized b y increasing t h e rate of discontinuous phase and b y t h e use of packing. Smaller sized distributor holes for t h e discontinuous phase influenced the over-all coefficient of mass transfer and the transfer unit values; t h e smaller the size t h e greater the capacity and ef ficiency of t h e tower. A tower packed with Raschig rings w a s found t o have the greatest capacity a n d a slight edge over Berl saddles. Consideration of other factors such as flood point, pressure drop, and holdup indicated that Berl saddles are probably the better of the two. Knit cloth w a s also used a s a packing material and, in addition t o a packed tower, a bubble cap plate tower, a perforated plate tower, and a spray tower were used. Copper knit cloth had little if any advan tage over spray columns; perforated plates a n d bubble cap columns were about equally efficient. N o practical difference w a s observed between 1/16-, 1/8-, and 3/32-inch diameter holes in per forated plate towers. This arrangement was more efficient t h a n t h e spray column or a column packed w i t h copper knit cloth, b u t much less efficient than a tower packed w i t h Berl saddles or Raschig rings. Values of t h e height of t h e transfer unit in feet for the toluene film for the various packings are Raschig rings, 52; Berl saddles, 6 4 ; perforated plates, 3 / 32 -ineh holes, 106; bubble caps 3 / 32 -inch 109; knit cloth, 170-189; spray column 1 / 1 0 inch holes, 186; a n d spray column 3 / 3 2 inch holes, 320. ACETONE
AND ETHANOL
RECOVERY.
D . F . Othmer.and E . Trueger, Polytechnic » Sherwood, T. K. f Shipley, G. H., and Halloway, F. Α., Ind. Bng. Chem., 3 0 , 765 (1938).
EDITION
Institute of Brooklyn, presented a paper on recovery of acetone and ethanol by solvent extraction. I n t h e past liquidliquid extraction w a s resorted to only when i t was impossible t o rectify. T h e authors stated that even with liquids commonly separated b y distillation, countercurrent extraction followed by dis tillation is a more economical method of separation. Chief savings were said t o be in the amount of heat required for the rectification of the relatively concentrated liquid extract as compared t o the dilute solution before extraction. Another ad vantage, they said, is the smaller distilla tion equipment required. PREDICTING M A X I M U M T E M P E R A T U R E S .
A method for predicting maximum tem peratures obtained in long-tube vertical evaporators was given b y O. C. Cessna and W . L. Badger, Swenson Evaporator Co. T h e data were obtained o n a 3 /4-iuch tube, 18 feet 6 inches long, and are a corre lation obtained w i t h water and sucrose solutions. I n normal operation, the longtube vertical, natural circulation evapora tor usually performs t w o functions— raising the temperature of t h e liquor fed to the tubes and evaporation of a por tion of the water in t h e liquid. Each tube, therefore, m a y be divided into a nonboiling and a boiling section. Heat transfer coefficients are different in each portion of the tube and consequently performance of t h e evaporator is depend ent o n the relative portion of the tube occupied b y the different sections and on the different coefficients of transfer. T h e mathematical prediction of maximum liquid temperature is necessary for correct design. HEAT TRANSFER.
M . J a k o b and K . A.
Rees, Armour Research Foundation, were authors of a paper o n heat transfer t o a fluid in laminar flow. T h e y told of ex periments i n which ethylene, hydrogen, and air in laminar flow through a long narrow annulus were heated and a vari able, depending o n t h e radius of t h e an nulus, heat conductivity of t h e gas, and heat transfer coefficient of the heated sur face, was calculated and found t o b e fairly constant for all conditions. HEAT
TRANSMISSION.
C.
F.
Bonilla
and C. W. Perry investigated heat trans mission to boiling binary liquids. T h e y concluded that t h e Insinger and Bliss correlation fitted the data accurately. FILM
AND H E A T
TRANSFER
COEF
FICIENTS. Individual film and heat trans fer coefficients for formic acid, phosphoric acid, and nickel sulfate-sulfuric acid solu tions obtained o n a Karbate tube were given a place in ; the literature b y R i E . Zinn, H . G. Thoemihg, a n d C. G. D u n can-Clark, Victor Chemical Works. T h e authors described t h e apparatus and test procedures used a n d reported that t h e y required n o special apparatus for obtain ing t h e temperature of t h e tube wall. All necessary temperature data were found from the liquids flowing in or out of t h e unit by the use of ordinary thermometers.
Vol. 19, No. 11 Even with thick walls, high over-all heat transfer coefficients were found t o be practical. T h e over-all U values ranged from 60 t o 1100. HYDROCHLORIC A C I D A B S O R P T I O N .
F.
L. Hunter, Fansteel Metallurgical Corp., gave a paper on hydrochloric acid absorp tion. Efficiency of absorption and cost of equipment were said t o depend on the method of liquid cooling. F o r liquids up t o 30 per cent hydrochloric acid con tent, t h e liquid cooling m a y b e accom plished b y evaporation of water from t h e acid, condensing t h e vapors, and re turning them t o t h e absorption zone. For acid strengths above 3 0 per cent this method is not successful, and t h e liquid must be cooled below equilibrium temperature if a concentration above 30 per cent is t o be obtained. CELLULOSIC R E A C T I O N S .
Physieochemi-
cal aspects in treating cellulosic m a terials were covered in a n extensive study b y R . M. Levy and H . McCormack, Illinois Institute of Technology. An attempt t o correlate cellulosic reactions with a general theory was m a d e and based on the reaction, observed b y t h e authors, between various types of cellulosic mate rials and many cooking liquids. Every solid when in contact with a liquid assumes an electrical charge as a result of selective adsorption of ions with respect t o t h e liquid; t h e oppositely charged ions are immobilized in t h e bulk of the solution t o maintain electrical neutrality. T h e electrokinetic potential set u p between t h e adsorbed ions and the bulk of t h e solution is k n o w n as t h e zeta potential, and t h e authors have worked o n several correlations between this charge and cellulose reactions and properties. I t was found t h a t the greater the zeta potential, for instance, t h e greater amount of pectin removed from cellulosic materials b y certain salts in the cooking liquors. With salts of high negative zeta potential, sodium hydroxide as one, both lignin and pectin are re moved from t h e raw cellulose. Salt solutions, having low zeta potentials at the cellulose-liquid interface, remove pectin and n o t lignin and a high value of zeta corresponds t o high lignin and pectin removal. As zeta decreases, t h e lignin removal property also decreases and only pectin compounds are removed. U p o n further decrease of zeta, t h e pectin removal characteristic becomes small. From these and other results t h e authors concluded t h a t pectic compounds and lignin are not combined w i t h the cellulose molecule as i s sometimes stated, b u t are merely present as adsorbed or encrusting constituents. T h e y also definitely estab lished t h e conclusion that t h e reaction be tween t h é various lignins a n d organic amines was one of adsorption followed b y a condensation with t h e aldehydic groups in the lignocellulose materials. SOYBEAN O I L E X T R A C T I O N .
H o w soy-
bean oil is extracted w i t h furfural was told t o t h e institute in a paper b y R. F .
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641
NEWS
642 Ruthruff and D . F. Wilcox, 3berwin Williams Co. As a premise for this paper the authors claimed that use of soybean oil in applications where drying properties are necessary, such as paint, varnish, linoleum, and ink manufacture, is very limited. Only 7.5 per cent of the total soybean production was so employed in 1939. B y far the greater application they said was in uses where unsaturation is unnecessary or even undesirable. If a cheap and effective solvent extraction process were available for the removal of the more highly unsaturated fraction from raw soybean oil, such a fraction would be more useful than the raw oil in the paint industries and the remainder would be as suitable a s the raw oil where unsaturation is u n d e s i r a b l e . Consequently the authors studied solvent e x traction of soybean oil and found that furfural possessed t h e most desirable
Vol. 19, No. 11
EDITION
qualifications as a solvent for this use. The furfural settles with the high iodine number extract, while the low iodine raffinate plus a small amount of furfural stays on top. Natural antioxidants are formed in the furfural extract by the fur fural itself, and as a second step to prevent this the natural oil in the furfural ex tract is removed by paraffinic hydro carbon solvents, such as petroleum ether or naphtha—a treatment which effec tively removes the furfural antioxidants. RESIN-TREATED
PLYWOODS.
Use
of
an alkaline, catalyzed, practically unpolymerized phenol-formaldehyde resin mixture was found by A. J. Stamm and R. M. Seborg, Forest Products Labora tory, to be one of the most suitable com pounds for impregnating plywood with a view to permanently reducing shrinking and swelling. Plywood made in this manner showed a marked decrease in
moisture transfer under a relative hu midity gradient. The decay resistance and the compressive strength of the wood was appreciably increased. Compressed resin-treated spruce in parallel plies was made with a specific gravity of 1.3, a tensile strength parallel to the grain of over 40,000 pounds per square inch, modulus of rupture 40,000 pounds per square inch, and crushing strength with compression parallel to the grain of over 20,000 pounds per square inch. Possible uses of the resin-treated plywoods are in airplane construction for fuselage and wing coverings, spar plates, and pro pellers. Laminated wooden propellers are being made with half-inch thicknesses of resin wood scarfed to normal spruce. It is thought that a propeller may be made with a varying specific gravity at right angles to the blade direction as well as in the blade direction.
