BRIEFS Summary of papers published in this month's research quarterly, I&EC Process Design and Development Canada
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MECHANISM, KINETICS, AND EQUILIBRIUM OF THERMAL DECOMPOSITION OF AMMONIUM SULFATE
T h e thermal decomposition mech,anism of ammonium sulfate, the reaction rate and equilibrium of deammoniation from ammonium sulfate, and the reaction rate of the dehydration of ammonium bisulfate were investigated by DTA, TG.4, and x-ray diffraction. i\mmonium sulfate on heating decomposed into triammonium hydrogen sulfate or ammonium bisulfate, which subsequently decomposed into ammonium pyrosulfate or sulfamic acid, and finally into several gases. The activation energies for the deammoniation and dehydration were calculated, and the enthalpy change of the deammoniation was evaluated. T h e results of this work should be helpful i n many industrial processes dealing with a.mmonium sulfate or its thermal decomposition products a t elevated temperatures.
Raisaku KGoura and Kohei Urano, Tokyo Institute of Technology, O-okay ama , M e g u r o - ku , Toky 0, J a p a n IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 489-494 (1970)
CONSIDERATION OF SENSITIVITY AND PARAMETER UNCERTAINTY
Sensitivity analysis is applied to reveal important parameters in the optimal design of a tko-stage continuous-flow stirred-tank reactor system with recycle. The specific example of a two-tank biological waste treatment system is examined t o detect parameters to which the optimal total holding time is most sensitive. The total holding time is most sensitive with respect to the efficiency of the thickener, next the recycle ratio, and thirdly the maximum specific growth rate (in order of decreasing sensitivity). Several optimal design strategies which take into account parameter uncertainty are proposed. One of these, the expected value criterion, has been uscd to find new optimal results and quantitative safety factors for the two-tank biological waste treatment system. I n general, the optimal total holding time should be increased as the range of uncertainty increases. Results are presented for normal and uniform parameter distributions.
M . S. K . Chen, L . E. Erickson, and L.-T. Fan, Kansas State University, Manhattan, Kan. 66502
IND. ENG.CIIEM. PROCESS DESIGN DEVELOP. 9,514-521 (1970) MODEL PREDICTIVE TIME-OPTIMAL CONTROL OF SECOND-ORDER PROCESSES
Set point changes for second-order processes are implemented using a hybrid computer and a fast-time model of the controlled process to search out the time-optimal trajectory. Process outputs are used as initial conditions to monitor the process transition i n continuous, closed loop fashion. Model scan rates u p to 100 per second (with convergence to the optimal solution i n milliseconds) furnish a continuous updating of predicted switch times for the controlled process and make possible the multiplexing of a single hybrid controller to a large number of controlled processes. T h e controller has excellent characteristics for set point changes and also as a regulator with both analog simulated processes and an experimental two-tank liquid level system.
D . A. Mellichamp, UniversiQ of California, Santa Barbara, Calq. 93106 IND. ENG.CHEM.PROCESS DESIGN DEVELOP. 9,494-502 (1970) OPTIMAL THERMAL DESIGN OF A N AUTOTHERMAL AMMONIA SYNTHESIS
The following optimization problem is considered : T o maximize profit by optimal choice of heat transfer coefficient as a function of reactor length, feed gas temperature, and reactor length, subject to the physical laws governing the behavior of an autothermal ammonia synthesis reactor and upper and lower bounds on tkie heat transfcr coefficicnts. Assumptions are made about the economics that reduce the profit objective to a weighted sum of reactor length and ammonia yield. The results are presented graphically i n parametric form to permit application with little additional computation. 'The effect of a variable heat transfer coefficient is considerable. For a reactor 5.18 meters long increase in ammonia yield is 5.470; at constant yield the reactor can be shortened by 17%,. The assumptions about the economics are then relaxed. Economic groups are defined which characterize the profit objective. The optimal design is insensitive to some groups over the range of interest, so that valid simplifications of the objective function can be made.
Akira Murase, H . L. Roberts, and A . 0. Conuersc, Dartmouth College, Hanooel-, h'. H . 03755 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 503-513 (1970) 74
INDUSTRIAL A N D ENGINEERING CHEMISTRY
KINETICS OF THERMAL DECOMPOSITION OF PULVERIZED COAL PARTICLES
.4n apparatus is described for measuring the extent of thermal decomposition of size-graded coal particles in the pulverized-fuel size range at temperatures up to 1000°C and times ranging from 30 t o 110 msec. The particles are heated to the decomposition temperatures a t high rates (25,000-50,000 "C/sec) comparable with those occurring in pulverized-fuel firing. The yield of volatile products under these rapid heating conditions was 1.3 to 1.8 times higher than the change in volatile matter found from the difference between the proximate volatile matter of coal and that of char. Analysis of dara obtained for 10 bituminous coals and one semianthracite yielded empirical equations suitable for calculating the progress of devolatilization of pulverized-fuel-particles when their temperatures history is known.
Stanley Badzioch and Peter G. W. Hawksley, B C U R A Industrial Laboratories, Leatherhead, Surrey, England
IND. END.CHEM.PROCESS DESIGN DEVELOP. 9,521-530 (19'70)
EFFECT OF PARTICLE DIAMETER AND APPARENT PARTICLE DENSITY O N INTERNAL SOLID CIRCULATION RATE IN AIR SPOUTED BEDS
Quantitative evaluation of the internal circulation rate of solids in a spouted bed system would be helpful to a study of fundamentals of the technique. In this study, unsteady-state mixing data obtained by bawh air spouting of two differently colored rrgion beds were utilized in a mathematical flow model to obtain the solid circulation rate. h 150-min.-diameter column fitted with a cone of 30' angle (half angle) and an inlet orifice of 9.52-mrn.diameter was used for spouting sand, coal, mustard, arid sago. The effect of fluid mass flow,rate on solid circulation rate is more dominating than other factors investigated in the work. Solid circulation rates were correlated with reduced fluid mass flow rate, particle diameter, and particle density.
W
=
870 Gr
(pp)-0,17
(D,)0.27
Mathur and Gishler (1955), estimated solid flow in the annulus from the particle velocity observed at the column wall. Thorley et al. (1959), followed the same principle of estimation taking into
account the radial movement of the particles in a semi-circular sectioned column. Particle velocity data at the wall does not reflect the solid flow pattern in the top section of the bed and also in the cone region.
Asok Chatterjee, Indian lnstitute of Technology, Bombay, India IND.END.CHEM.PROCESS DESIGN DEVELOP. 9,531-536 (1970) ACETYLENE HYDROGENATION IN A BUBBLE COLUMN SLURRY REACTOR
The hydrogenation of acetylene in a bubble column slurry reactor (BCSR), using Raney nickel catalyst with process water as the inert liquid medium, was studied a t several flow rates, temperatures, catalyst loadings, and hydrogen to acetylene feed ratios. The effect of these variables on selectivitiy, acetylene conversion, and product distribution was determined. The effect of process time on catalyst activity and selectivity was also investigated. Fractional conversion of acetylene to ethylene and ethane was strongly dependent on process time. This dependence was attributed to polymer formation on the most active sites of the catalyst. After long proces time it is believed that catalyst sites with sufficient activity to permit polymerization are essentially covered with polymer. However, many of the remaining catalyst sites have sufficient activity to allow the reaction, acetylene to ethylene to ethane, to proceed.
Ronald M. Heck and Theodore G. Smith, University of Maryland, College Park, M d . 20740 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 537-540 (1970) PHOTOCHEMICAL DECOMPOSITION RATES OF POTASSIUM FERRIOXALATE IN A CONE-SHAPED REACTOR
Decomposition rates of the photochemical reaction of 0.006M potassium ferrioxalate in 0.1N sulphuric acid were studied. A tungsten source was employed to emit radiation of sufficient intensity in the 300- to 600-mp wavelength region. The reaction was carried out in six cone-shaped reactors (about 20 to 2600 cc), and batchwise experiments were conducted with the light source located at the apex. Conversions were approximately 1.5% and the production rate increased by 23.5y0 from the smallest to the largest reactor. The concentration dependence of the rate expression was not determined. A unique feature is the use of a point light source in cone-shaped reactors to determine reaction rate. This eliminated the problem of skewed light resulting from linear sources. Literature values of quantum efficiencies as a function of wavelength were used to predict results of experiments, and comparison was made for quantum efficiency of one. Use of wavelength dependence gave better predictability.
P. R. Harris, M . C. H a w l g , and M . H. Chetrick, Michigan State UniversiQ, East Lansing, M i c h . 48823
IND.ENG.CHEM.PROCESS DESIGNDEVELOP. 9, 540-545 (1970) SEPARATION OF TWO IMMISCIBLE LIQUIDS IN A HYDROCYCLONE
JACKET-SIDE NUSSELT NUMBER
Experimentally derived values of the over-all heat transfer coefficient and published data for the vessel side were used to derive a jacket-sidte Nusselt number. This was compared with the Prandtl analogy relation Nu = f R e P r / 2 ( l f 4[Pr - 11) in which f and 4 have enipirically determined values. Published data were used for f and the equivalent diameter. Three velocities that follow from apparatus dimensions, flow rate, and temperature rise were combined to yield a characteristic velocity for Re. Water was injected radially or tangentially into a vertical cylindrical jacket with height/diameter 'v 1. Flow rates varied from 0.12 to 0.57 lb,/sec-sq ft of heat transfer area. Experimentally derived and calculated results were in reasonable agreement. The friction factor and equivalent diameter modifications, together with the characteristic velocity, can be used also in other appropriate heat transfer equations, with similar agreement.
I . H. Lehrsr, Monash University, Victoria, Australia IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 553-558 (1970)
GAS FLOW AND PRESSURE DROP THROUGH MOVING BEDS
Characteristics of air flow through moving beds were observed using two kinds of tubes, 4.1 and 7.0 cm in i.d., and four kinds of glass beads, &I = 133, 261, 430, and 1130 microns. Longitudinal pressure gradient was determined by slip velocity of gas relative to the descending solids; the gas flowing into the moving bed from the feed hopper played an important role in determining the mass balance at the gas outlet.
Sok Mooii Yoon and Daizo Kunii, University of Tokyo, Tokyo, J a p a n IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 559-565 (1970)
HYPERFILTRATION. APPLICATION OF WOVEN FIBER HOSES TO HYPERFILTRATION OF SALTS AND CROSSFLOW FILTRATION OF SUSPENDED SOLIDS
Hyperfiltration tests showed that it is possible to form salt-rejecting membranes from a variety of additives on woven hoses coated with filter aid. Intrinsic salt rejections as high as 85y0with production rates of 95 gpd/ft2 were observed a t pressures of 275 psig, even though no attempt was made to optimize fiber weave, filter aid, and additive. I t is possible to remove clear water at high production rates from a suspension of micron-sized particles by pumping through fiber hoses under moderate pressures. Production rates were proportional to circulation (crossflow) velocity (2 to 40 feet per second) and temperature (18' to 55OC) and showed little dependence on solid concentration in the range of 3 to 80 grams per liter.
J . A . Dahlheimer, D. G. Thomas, and K . A. Kraus, Oak Ridge hrational Laboratory, Oak Ridge, Tenn. 37830 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 566-569 (1970)
The separation of a mixture of carbon tetrachloride in water was studied in a 2-inch diam glass hydrocyclone. The work first considered the effect of oil/water ratio and pressure drop across a mixing valve on the volume/surface diameter of the oil/water mixture. A linear relation between valve pressure drop and the volume/surface diameter was found. Oil/water ratio had no statistically significant effect. Secondly, the effect of feed drop size distribution, feed oil/water ratio, and volume split on the separation efficiency of the cyclone was studied. Ranges of the variables were: Feed drop size, 150p < ( D P ) u < 3 0 0 p ; Volumetric oil/water ratio, 0.135 to 0.210; volume split, 4/1 5 overflow/ underflow 5 8/1. For the range of variables studied, the variables in decreasing order of importance are: volume split, oil/water ratio, feed drop size distribution. Results of the separation work could be explained by assuming no drop-drop coalescence and no short circuiting. The overflow drop size distribution could also be predicted using the above assumptions.
As a study of the hydrocarbon fermentor, variation of the volumetric coefficient kLa for oxygen absorption into water with the addition of kerosine, liquid paraffin, toluene, and oleic acid as the dispersed phase, as well as a surface active agent, was investigated by use of a continuously operated gas bubble column and a gasliquid contactor with a turbine-type agitator. I n the kerosine-inwater and paraffin-in-water systems, both with negative spreading coefficients, kLa decreases linearly with increasing oil fraction. I n the toluene-in-water and oleic acid-in-water systems, both with positive spreading coefficients, k L a initially decreases and then increases with increasing oil fraction. Effects of addition of a surface active agent to water are similar to those with the toluenein-water and oleic acid-in-water systems.
K. A. Burrill and D . R. Woods, McMaster UniversitJv, Hamilton, Ont., Canada
Fumitake Yoshida, Tsuneo Yamane, and Yoshio MGamoto, Chemical Engineering Department, Kyoto University, Kioto, J a p a n
IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 545-552 (1970)
IND.END.CHEM.PROCXSS DESIGN DEVELOP. 9, 570-577 (1970)
OXYGEN ABSORPTION INTO OIL-IN-WATER EMULSIONS. A STUDY ON HYDROCARBON FERMENTORS
VOL. 6 2
NO.
10
OCTOBER
1970
75
The Pump That Never Gets Wet
OPTIMIZATION OF LINEAR FIXED-BED SEPARATIONS
Optimization of the separation of solutes by fixed beds is considered. .+plication of a general optimization principle to the purificarion of uremic lymph by gel filtration is discussed in detail. This example illustrates that, in some cases, optimization of the resolution index with respect to displacement velocity may be less preferable than simply minimizing the time required for separation, subject to limitations such as pressure drop.
D . 0 . Gooney, Clarkson College of Technology, Potsdam, N . Y . 13676 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 578-580 (1970) CHEMICAL PROCESS OPTIMIZATION USING PENALTY FUNCTIONS
MA
RANDOLPH PUMP F L U I D S FLOW THROUGH A FLEXIBLE TUBE WITHOUT CONTACTING THE PUMP
....................................................
C A P A C I T I E S U P T O 200 G A L L O N S PER H O U R
FOR FREE CATALOG CONTACT THE RANDOLPH CO 3054-A ROSINE ST. HOUSTON, TEXAS 77019 P h o n e (713) 526-2091 E x t e n s i o n 506
INTERACTION OF LIQUIDS AT SOLID SUBSTRATES ADVANCES IN CHEMISTRY SERIES NO. 87 Papers from two symposia by the Division of Organic Coatings and Plastics Chemistry of the American Chemical Society. This volume includes twelve papers comprising t h e symposium on “The Interaction of Liquids at Solid Substrates,” chaired by Allen L. Alexander. These papers include work on “coupling agents,” adhesion of polymers, organic/inorganic interfaces, and ultrasonic impedometry. Also included are four papers concerned with heparinized surfaces at the blood/material interface which were part of t h e symposium on “The Medical Applications of Plastics,” chaired by R. I. Leininger.
212 pages with index
Clothbound
(1968)
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76
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
A penalty function technique can be used to optimize continuous, nonlinear, chemical process problems of moderate dimensionality. The method is applied to the optimal separation of four isomers of a gasoline blending stock. Optimal solutions are presented, and the characteristics of the method are discussed. The method is efficient and trouble-free for this example. I t has t w o generally favorable characteristics compared w-ith other nonlinear programming techniques: The constraints need not be satisfied until the end of the computation, which implies that recycle loops need not be closed, product specifications need not be satisfied, etc.; and the algorithm is noniterative i n the sense that a trial-and-error procedure, which may or may not converge, is not utilized.
B. S.Gottfried, P. R. Bruggink, and E. R. Harwood, Guy Research @ Development Go., Pittsburgh, P a . 15230 IND.
ENG.CHEM. PROCESS DESIGN DEVELOP. 9, 581-588 (1970)
INFLUENCES OF CATALYST FORMULATION AND POISONING O N THE ACTIVITY AND DIE-OFF OF LOW TEMPERATURE SHIFT CATALYSTS
The use of copper catalysts for the low temperature shift reaction has become much more widespread in the last decade in hydrogen and ammonia synthesis gas production. This has led to a general awareness among plant operators of the problem of catalyst dieoff, Die-off is shown to be the consequence of two factors: thermal sintering, which can be reduced, and in some cases eliminated, by correct catalyst formulation methods, and poisoning by small concentrations of impurities such as sulfur and chlorine, carried in the gas stream. T h e importance of the method of catalyst manufacture on subsequent activity and stability is outlinrd; with a wellformulated catalyst, not maltreated, poisoning is the major cause of loss of activity on the commercial scale. The reaction kinetics, using a commercially available catalyst, have been examined and a d e s i p equation is proposed. The acLivity of the catalyst, in the absence of a diffusion limitation, is directly proportional to the copper area and initial activity increases with increasing copper content. The use of hydrogen in steam for reduction of the catalyst is discussed.
J o h n S. Camfibell, Imperial Chemical Industries Ltd., Billingham, l’eesside, England IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 588-595 (1970) IMPROVEMENT OF IRON LEACHING I N CLAYS. OPTIMIZING PROCESSING PARAMETERS IN SODIUM DlTHlONlTE REDUCTION
Many parameters influence the brightness improvement of kaolin clays by dithionite leaching. Control cannot be exercised over all -e.g., crystallinity, impurities, and particle size-others, controllable, influence the chemical reaction profoundly. The ultimate purpose of improving the leaching reaction is to attain enhanced brightness at reduced economy; brightness itself is a poor criterion for efficiency measurements because of relatively high analytical error. Potentiometric measurements are sensitive to parameter variation and correlate well with optical properties and have been employed to study reaction parameters. Poorly crystallized
and very fine particle size clays retard decomposition of dithionite. Temperature increases the rate of decomposition, reduction potential, and iron solubilization, and improves the leach reaction. At 60°C. an optimum leaching temperature is reached. Ionic contamination is significant. Acidity is of great importance. Slurry solids exert a minor influence on the leach reaction. Controlled incremental dithionite addition improves the process.
R. F. Conley and M . K . Lloyd, Georgia Kaolin Co., Elizabeth, N . J . 07207
IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9,595-601 (1970) INDIVIDUAL FILM RESISTANCES IN LIQUID EXTRACTION IN A 1-INCH ID YORK-SCHEIBEL
Mass transfer in a York-Scheibel column was studied using a binary system. Film resistance in one phase was eliminated by presaturation with the second phase. I n the system isobutanolwater, the height of a transfer unit, dispersed phase, was independent of continuous and dispersed flow rates. The height of a transfer unit, continuous phase, was dependent on both flow rates and could be represented as (HTU)c = Ka ( L c ' ) m ( L ~ ' )Inn this work, m = 0.95 and n = -0.80. A simultaneous study of the effect of agitator speed on each of the HTU's showed (HTU)Dto be inversely proportional to agitator speed, and ( H T U ) c to be a complex function( which was not determined) of agitator speed.
J . W. Miller, Jr. and F. J . Eastburn, University of Louisville, Louisville, Ky. 40208
Projects extremely wide hollow cone spray in choice of 1 2 0 " , 150" and 180" spray angles. Capacities from 1.2 to 15.8 GPM at 100 psi. Write for Bulletin 146.
Jet-Wbr
ADAPTERs
To eliminate effects of turbulence in ClOSe-COUDkd manifold. tee and elbow nozzle mount'ings. Steadies spray pattern, increases impact of flat spray nozzles. 1/8" to 11/4'' NPT sizes. See Bulletin 148.
WALL MOUNTEDFU&?tB
NOZZLES
Permits wall mounting where nozzle sprays in enclosed vessel or tank. Full cone spray in choice of capacities from 0.30 to 3 4 9 GPM at 100 psi. Write for Catalog 25A.
TO AIR ATOMIZE HIGH VISCOSITY FLUIDS Mixes air and liquid externall
. . . for spraying higher
viscosity fluids or abrasive suspensions. Choice of capacities from 0 . 8 to 72.0 GPH. Write for Bulletin 153.
SPRAYING SYSTEMS CO. 3255 Randolph Slnet, Bellwood, llllnolr 80104
IND. END.CHEM.PROCESS DESIGN DEVELOP. 9,601-604 (1970) HIGH VOLUME SUBMILLISECOND PRESSURE RELIEF EMERGENCY SYSTEM
A new design is described for a fast opening emergency relief system for high pressure vessels such as refinery blow down systems or nuclear reactor boiler rooms. By a simple electronic triggering circuit for timing, in conjunction with a double diaphragm arrangement and the exploding wire technique, very large pressure ranges can be covered. Experiments show that by choosing the proper influence parameters a submillisecond opening system of high reproducibility is obtained. T h e simplicity of the design allows many modifications and finds wide fields of application in safety systems of industrial facilities as well as in experimental equipment.
Sigmar L. K . W i t t i g , Instztut Jur Allgemeine Mechanzk, Aachen, Germany IND.ENG.CHEM. PROCESS DESIGN DEVELOP. 9,605-608 (1970) A STUDY OF THE INTERACTION OF SOLVENT AND CATALYST IN COAL HYDROGENATION
A study has been made of the interaction between catalyst and solvents on the extent of the liquid phase coal hydrogenation reaction. Samples of a subbituminous Wyoming coal were impregnated with varying amounts of ferrous ion catalyst and hydroThree different solvents were used. Differgenated a t 440'C. ences in the conversion levels attained that were attributable to the solvents first decreased as the concentration of the catalyst on the coal increased to 1.0 wt. yo. Further increase in the catalyst concentration had little effect on conversion. The results indicate that even when ferrous ion catalyst is used, the solubility characteristics of the solvent, as measured by the non-polar solubility parameter, are important in obtaining maximum yields of benzene soluble products. An additional experiment in which coal size was varied indicated that coal size is not an important variable.
G. R. Pastor, J . M . Angelovich, and H. F. Szlver, University of Wyoming, Laramie, Wyo.
ASSISTANT TECHNICAL DIRECTOR Leading international milling company seeks man to conduct cereal research, supervise quality control and work in the field with Company customers on product problems. Will report directly to Vice President and Technical Director. Must have minimum of five years' experience and MS degree in organic chemistry with some training in physical chemistry and in microbiology. Mid-west location. Some travel required. Excellent opportunity to advance. Send resume to Martin Hegarty, 645 North Michigan Avenue, Chicago, Ill. 60611.
IND.END.CHEM.PROCESS DESIGN DEVELOP. 9, 609-611 (1970) VOL. 6 2
NO.
10
OCTOBER
1970
77
BRIEFS CONTINUOUS LIQUID PARTITION FOR SEPARATION OF BIOLOGICALS
CARBON DISTRIBUTION FUNCTIONS IN A FLUID CATALYTIC CRACKER
Continuous liquid partition was developed and applied to separation of bacteria from atmospheric particulates. Two-phase aqueous solutions of dextran and polyvinyl alcohol were efTective media, in which bacteria (17 species) concentrated in the dextranrich phase, and natural background and particulates concentrated in the PVA-rich phase. ?, continuous centrifuge was developed for separating the liquid phases, which gave recovery of 95 to 100yc bacteria and elimination of 95 to 1 0 0 ~ background G in steady-state operation. Retention times were typically Ill2 to 3 minutes.
An iterative computational method was developed to obtain the carbon distribution functions for a fluid catalytic cracker. T h e F C C unit was idealized as a three-vessel system consisting of a backmixed regenerator, a plug flow riser reactor, and a backmixed reactor. S. M . Jacob, M o b i l Research and Develofiment Corfi., Paulsboro, X . J . 08066 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9,636-640 (1970)
L . T . Carleton and Theodore Crutchjeld, Aerojet General Carp. El Monte, C a l q . 9 I734 IND.ENG.CHEM.PROCESS DESIGNDEVELOP. 9, 611-618 (1970)
OPTIMIZATION OF A VINYL CHLORIDE MONOMER REACTOR
A model for the hydrochlorination of acetylene and catalyst decay reactions is used as a basis for a n optimization study. Feed rate, molar ratio of reactants, cooling jacket temperature, and inlet temperatures and pressures are found which maximize a functional containing both product values and catalyst costs. T h e optimal policies show that the controls should be adjusted to maintain the conversion nearly constant as the catalyst decays. The optimal catalyst loading resembles a sine wave in the spatial dimension for one example. The computational effort required to find the optimum for this distributed parameter problem was about 5 minutes on a 360/75. A . F. Ogunye and W. H . R a y , Uniuersity of Waterloo, Waterloo, Ontario, Canada IND.ENG.CHEM.PROCESS DESIGX DEVELOP. 9, 619-624 (1970)
MINIMIZATION OF CAPITAL INVESTMENT FOR BATCH PROCESSES
A procedure is described for calculating the sizes of interdependent pieces of equipment which minimize the capital investment of a batch processing plant. Power-law-type cost expressions are presented for both true batch and semicontinuous units and combined to form a n over-all objective function. Ordinary calculus is used to establish necessary conditions for optimum equipment sizes. These conditions lead to a set of one-dimensional algebraic equations, solvable by simple iterative techniques. A sample calculation illustrates the procedure and demonstrates the savings realizable in equipment costs.
Yashwant R. Loonkar and Jerome D . Robinson, American Cjanamid Go., W a j n e : >\-. J . 07470 I N D ENG. . CHEM.PROCESS DESIGN DEVELOP. 9,625-629 (1970)
REVERSE OSMOSIS SEPARATION OF SOME ORGANIC SOLUTES IN AQUEOUS SOLUTION USING POROUS CELLULOSE ACETATE MEMBRANES
Reverse osmosis experiments were carried out for the systems glucose-water (0.1 to 1.5M), maltose-water (0.03 to O.llM), lactose-water (0.04 to 0.221M), ethylene glycol-water (0.2 to 1.5iM), propylene glycol-water (0.2 to 0.8M),and ethylene glycolpropylene glycol-water (total molality 1. O M ) in the concentration ranges indicatcd. The correlations of data for the single solute systems were similar to those reported for the system sodium chloride-water. A relative scale of membrane selectivity is given for the organic solutes in terms of solute transport parameters. The results obtained wirh the mixed solute system show that the prediction technique already developed for aqueous solution systems containing mixed inorganic solutes with a common ion is applicable for systems containing nonionic mixed organic solutes. T h e performance of a typical film for the concentration of aqueous glucose solution is illustrated.
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Takeshi Matsuura and S. Sourirajan, ATatational Research Council of Canada, Ottawa, Canada IND.ENG.CHLM. PROCESS DESIGN DEVELOP. 9, 640-646 (1970)
CORRESPONDENCE
Comments o n an article on batch heat transfer coefficients for pseudoplastic fluids in agitated vessels.
V . S. V . Rajan, UniuersiQ of .Vew Brunswtck, Fredericton, S.B., Canada IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9,647 (1970)
FLOW PULSATION GENERATOR FOR PILOT-SCALE STUDIES
;\n air-pulsing technique involving no mcchanical moving parts was applied to water flows in 3:/4- and 2-inch pipes at time-average Reynolds numbers from 3000 to 66,000. T h e frequency (0.35 to 1.1 cycles per second) and displacement (up to 2.5 feet) are sufficient to cause flow reversal. A numerical technique for predicting the pulsator performance has been developed, bur its accuracy is limited by uncertainties about two-phase flow. I n its present form, the technique gives a conservative estimate of pulsation intensity.
CORRESPONDENCE
Comments on a n article on rate of ball milling and vibration milling on the basis of the comminution law. Probability theorem.
C. R. Milburn and 14.4. H. I . Baird, n/fc:Master Lrniversib, Hamilton, Ontario, Canada
M . Balasubramanian, Unioersity o j Waterloo, Waterloo, Ontario, Canada Tatsuo Tanaka, Hokkaido UniuersiQ, Sapporo, Jajan
IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 9, 629-635 (1970)
I N D .ENG.CHEM. PROCESS DESIGN DEVELOP. 9,647 (1970)
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INDUSTRIAL AND
ENGINEERING CHEMISTRY
