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DEVELOPMENT OF A LABORATORY SCALE CONTINUOUS MULTISTAGE EXTRACTOR .\ small continuous multistage box-type mixer-settler extractor
has been designed, constructed, and opcratcd to study rhr frasibility of separdtiiig the indi\,idual rare earths from each ut1ir.r iisiiig 1.11 dic 2-ethylhexyI)phosphoric acid in .\nisco odorless mineral spirits as the activc solvent and a dilutc IiCl solution as the heavy phase or scrub solvent. Preliminary results indicate that the cxtractor operates satisfactorily for this purpose, although extensive studies on the influence of operating conditions on stagc eficicncics ha\-e not been carried out. T h e extractor uses the pump-mix principle in mixing chambers and individual interface control in settling chambers. Removable Plexiglas inserts reducr the capacitance of the system and enhance approach to steady state.
trials by varying initial conditions for checking that the result is the global minimum, rather than a local one, but this does not lessen its applicability to the optimal design of process systems.
Tomio Umeda, ChGoda Chemical Engineering 3 Construction Go., Ltd., Tokyo, Japan IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8 , 308-317 (1969)
SORPTION OF SULFUR DIOXIDE BY ION EXCHANGE RESINS
Rate and equilibrium data are presented for sorption of sulfur dioxide on a weak base, macroreticular ion exchange resin. Rates are limited by intraparticle diffusion. Equilibrium loadings at 25 OC compare favorably with other adsorbents.
Richard 11'. Rahn and .lforfcn Sniufz, Inrrirute fw .4ron;Zc Rr:t*arr/i and Deparfmrnt cf C'htnrical Etiginteritig, I0ti.a Sfore [.'?I~L e r j z ! ) , :h;, Lawrence Layton and G . R. Youngquist, Clarkson College of Technology, Potsdam, iV. Y. 73676 Iouja 50010 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8, 317-324 (1969) ISD. ESG. CIIEM. PROCESS DESIGSDEVELOP. 8, 289-293 (1969)
DESIGN PROCEDURE FOR LAMINAR, ISOTHERMAL, NON-NEWTONIAN FLOW IN PIPES AND ANNULI
TRANSIENT RESPONSE OF A PACKED COLUMN TO CHANGES IN LIQUID AND GAS FLOW RATES
Isothermal, viscometric flow data are numerically simulated for pipes and annuli by using the extended Williamson model. T h e design criteria are presented in terms of a design equation relating the process variables and a tube-apparent Reynolds number defining the laminar-turbulent transition. Plots of design variables for select values of extended Williamson model parameters, annuli radius ratio, and viscosity ratio describe the flow behavior of pseudoplastic and dilatant fluids.
T h e holdup of a film of liquid flowing down a plate was theoretically found to be a first-order system regarding the flow rate through the film. Based on this conclusion, the dynamic holdup of a packed column can be considered as a system of small firstorder elements in series, the response of which can be lumped into a time delay and a time constant. The pressure drop and holdup characteristics were determined for a column packed with Dixon rings and operated with countercurrent flow of air and water. T h e transient response of the liquid outflow rate to changes in liquid and gas flow rate was investigated. For small-step function disturbances the responses to positive and negative-step changes were symmetrical ; for larger disturbances they were asymmetrical. Time delays and time constants were correlated in terms of theoretical mean response time.
S. D . Cramer and J . M . Marchello, Universip of Maryland, College Park, M d . 20742 IND.END.CHEM.PROCESS DESIGN DEVELOP. 8, 293-298 (1969)
FUEL FOR THE SUPERSONIC TRANSPORT. EFFECTS OF DEPOSITS ON HEAT TRANSFER TO AVIATION KEROSINE
Chaim Gilath, L. M . Naphtali, and William Resnick, Israel Institute of Technology, Haifa, Israel
A single-tube heat exchanger rig, designed to reproduce the conditions to which aviation turbine fuel will be subjected in the fuelcooled oil coolers of the supersonic transport, was constructed to study the behavior of fuels exposed to elevated temperatures. The thermal stability of a fuel, deduced from heat transfer data, correlates with the breakpoint temperature measured with the AS'rMCRC fuel coker. T h e behaviors of smooth cylindrical bore tubes and tubes containing turbulence promoters have been compared and the effects of varying the mass flow rate evaluated. The factors involved are discussed.
IND.END.CHEM.PROCESS DESIGN DEVELOP. 8 , 324-333 (1969)
J . D . Smith, Shell Research, Ltd., Thornton Research Centre, Chester, EngIand IND.END.CHEM.PROCESS DESIGN DEVELOPMENT 8,299-308 (1969)
OPTIMAL DESIGN OF AN ABSORBER-STRIPPER SYSTEM. APPLICATION OF THE COMPLEX METHOD
T h e absorber-stripper system, which has a complicated structure with recycle of absorbent as well as recovery of heat, has been successfully optimized by the Complex method developed by Box. The system contains five independent design variables which have to be decided so as to minimize some objective function, like production cost, under various constraints. Like other optimal seeking methods, the Complex method requires several 42
INDUSTRIAL A N D ENGINEERING CHEMISTRY
CLASSICAL APPROACH TO BANG-BANG CONTROL OF LINEAR PROCESSES
Time-optimal control of a general class of nth-order linear processes with nonpositive real poles, processes commonly encountered in chemical industries, is treated systcmatically by a classical approach based on a simple property that the Laplace transforms of truncated functions are entire functions. A set of n nonlinear equations is derived, which, when solved, yields switching times, minimum time, and switching boundaries (curve, surface, or hypersurface). Hence, time-optimal computations are reduced to solving these equations for roots. -4nalytical expressions are possible for simple low-order processes, while some iteration or approximation techniques are necessary for high-order processes. The advantages of this approach are its ability to handle, in general form, processes with real poles, distinct or repeated, zero or negative, and computational short cuts. For illustration, examples of second-order processes, a third-order process, and an nth-order process with distinct negative real poles, the only process treated in general form by time-domain analysis, are given.
H. C. Lim, Purdue UniuersiQ, West Lafayette, Ind. 47907 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8 , 334-342 (1969)
SHELL-SIDE HEAT TRANSFER COEFFICIENTS IN HELICAL COIL HEAT EXCHANGERS
Geometric construction parameters-winding angle, radial pitch, and axial pitchsignificantly influence the shell-side heat transfer of helical coil heat exchangers. Shell-side heat transfer coefficients have been calculated from experimental measurements of over-all coefficients for both water and air as the shell-side fluid. Water was used in the tubes for all measurements. Tube-side heat transfer coefficients were determined from the Dittus-Boelter equation, which was checked for several cases by the Wilson plot technique. The shell-side heat transfer coefficients of six heat exchangers have been correlated by the relationship: NN" = c N R ~ ~ N PEquations ,~. relate parameters a, 6, and c to the construction variables.
C. J . Messa, A . S. Ioust, and G. W. Poehlein, Lehigh Universig Bethlehem, Pa. 18075 IND.ENG.CHEM.PROCESS DESIGNDEVELOP. 8, 343-347 (1969) EXPERIMENTAL STUDY OF THE ICE-MAKING OPERATION I N THE INVERSION DESALINATION FREEZING PROCESS
Experimental equipment was designed and built to test the ice making of the inversion desalination freezing process at atmospheric pressure. A back-mixed type contactor was used to produce ice from salt water by direct contact freezing, using a mixture of n-tridecane and n-tetradecane as a working medium. The thermal driving force, degree of mixing, and nominal residence time were studied as controlling variables for the ice production rate, using 47 experimental runs and four working media. The agitation speed ranged from 300 to 900 rpm, and the nominal residence time from 86 to 238 seconds. Pictures obtained under different operating conditions showed that ice crystals were fairly large, well-shaped, and smooth. The results of the production rate study can be used to design a larger scale plant. Very reasonably sized equipment may be used. The quality of ice indicates that the ice-washing operation should present no problems.
An important Spraying Systems advantage is greater nozzle selection to meet your specifications. For example, Whirllet nozzles are available in over 500 types and sizes . 0.07 t o 1055 GPM, capacities . 50" to 165" spray angles. Material selection includes brass, steel, stainless steel, Nylon PVC and other materials.
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Shen-yann Chiu, Liang-tseng Fan, and R. G. Akins, Kansas State Univer-
sip, Manhattan, Kan. 66502 IND.END.CHEWPROCESS DESIGN DEVELOP. 8, 347-356 (1969) ELECTROSTATIC PRECIPITATOR ANALYSIS
Relations are developed to compare space charge with conventional electrostatic precipitators. Space charge precipitators have wall area requirements similar to conventional units, if the drops added to the gas are of the same general size as the particles to be precipitated. Space charge precipitators are considerably simpler in construction than conventional units and would be highly desirable if large quantities of small drops could be produced. Present designs of atomizing nozzles are not satisfactory for this purpose, but condensation of steam to form droplets appears feasible.
D. A'. Hanson and C. R. Wilke, University of Cali'fornaa, Berkeley,
Gal$ 94720 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8, 357-364 (1969)
One great advantage-of CHEMICAL ENGINEERHYDROGENOLYSIS OF ETHANE AND OF PROPANE OVER A COMMERCIAL RUTHENIUM CATALYST. KINETIC STUDY
The kinetics of ethane and propane hydrogenolysis were studied over a a commercial 0.5% ruthenium on yalumina catalyst. The ethane hydrogenolysis rate was first-order-dependent on ethane partial pressure and - 2-order-dependent on hydrogen partial pressure over a temperature range of 160' to 22OoC at 1to 2-atm total pressure. The propane hydrogenolysis rate was first-order-dependent on propane partial pressure and - 3/2order-dependent on hydrogen partial pressure over a temperature range of 140" to 17OoC a t 1-atm total pressure. The apparent activation energies were 42 kcal. for ethane hydrogenolysis and 35.8 kcal for propane hydrogenolysis obtained in a well-mixed gas-solid reactor operating over a wide range of conversions. Possible interpretations of the kinetic results are given.
D. G. Tajbl, Institute of Gas Technology, Chicago, Ill. 60676 IND.END.CHEM.PROCESS DESIGN DEVELOP. 8, 364-370 (1969)
ING CATALOG lies in the fact that you can secretly assemble virtually all the factual data you need without alerting vendors' salesmen or tipping your hand t o a competitor. C E C works hard for you, and for you alone -until you are ready to get down to cases with the suppliers you select. It's a great time-saver as well as a work-saver. Take your process problem into the 5-way index. Surround your problem with the needed facts about equipment, materials of construction or specialized services. Then work out your solution. CEC tells all, but keeps your secret!
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NO. 7 J U L Y 1 9 6 9
43
HOLDUP AND AXIAL DISTRIBUTION OF HOLDUP IN A PULSED SIEVE-PLATE SOLVENT EXTRACTION COLUMN
BRIEFS REACTIONS OF TITANIUM TETRACHLORIDE IN A RADIO-FREQUENCY PLASMA TORCH
Thermodynamic equilibrium yields, experimental coupling efficiencies, and experimental conversions for reduction of titanium tetrachloride were studied in a radio-frequency plasma torch operated with argon a t 1 atm pressure. Calculated equilibrium results are presented for systems Ar-TiC14, Ar-TiClp-Mg and Ar-TiCla-Hn with temperatures to 14,000'K a t 1 atm pressure. Experimental coupling efficiencies obtained for a 4-MHz radiofrequency torch operated with argon indicated that about 6091, of the generator plate power was transferred to the plasma. Efficiency appeared to be nearly independent of the power level and whether the stabilizing flow was vortex or coaxial. Hydrogen addition showed little effect on coupling efficiency, while Tic14 produced a decrease. Tic14 was reduced to Tic13 by Hz with 61 to 87y0 yields. Power input and Tic14 feed rate had little effect on the per cent conversion. Without Hz no appreciable reduction of Tic14 could be obtained with the quenching methods employed.
R. C. Miller and R . J . Ayen, University of California, Berkeley, Calif,
IND.END.CHEM.PROCESS DESIGN DEVELOP. 8, 370-377 (1969)
REGENERATION OF COKED CATALYST IN ADIABATIC FIXED BEDS AT LOWER TEMPERATURES
Simulation of the adiabatic regeneration process in fixed beds a t lower temperatures was studied. At lower temperatures, the burning rate is controlled by the intrinsic chemical kinetics, which has a much higher activation energy than the mass transfercontrolled regime. The higher temperature dependence of the rate constant causes a significant difference in the temperature and concentration profiles compared to the conventional regeneration process, such as the existence of minimum in the coke concentration profile. An implicit semianalytical solution for the quasisteady-state burning regime was obtained and shown to approach the unsteady-state solution asymptotically for larger times. This semianalytical solution greatly reduces the numerical solution time required for simulating the entire burning period.
Yuichi Orawa, Mobil Research
&? Development
Cor&., Paulsboro, N . J .
08066
IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8, 378-383 (1969)
ACTIVE SPECIES O N COKED SILICA-ALUMINA CATALYST
The rapid, initial temperature rise attending oxidation of coked silica-alumina catalysts is due to a highly reactive material residing on the coke surface. The active species is formed in the coking process and is present even after a mild prevolatilization treatment in nitrogen; but it may be removed or rendered inactive by pretreatment under vacuum or in nitrogen a t high temperature. A hydrogen-rich coke layer on the exterior of the basic coke particle is believed to be responsible for the effect observed.
F. E. Massoth and P. G. Menon, Gulf Research @ Development Co., Pittsburgh, Pa. 15230
A shutter plate system for measuring both over-all holdup and axial distribution of holdup in a pulsed sieve-plate solvent extraction column is discussed. In a 2-inch-diameter column the axial holdup profile went through a maximum approximately midway along the column axis for columns containing less than 23 cells, with a 2.2-inch plate spacing. For columns of 23 cells or more the holdup was uniform throughout. A large number of over-all holdup data are reported for a 26-cell column using the n-hexane-water and MIBK-water liquid systems. A correlation for over-all holdup good to 15% is presented, covering a wide range of operating variables for both systems.
R. L. Bell and A . L. Babb, University of California, Davis, Cahy. 95616 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8, 392-400 (1969) REACTION OF A PHOSPHATE ROCK WITH AN SOD-CONTAINING GAS MIXTURE TO MAKE SUPERPHOSPHATE
Experimental research was conducted to investigate the reaction of SO8 in the presence of water vapor, obtained from a synthetic flue gas mixture, and phosphate rock, to obtain a high conversion of tricalcium phosphate into available P2Oj form, as well as efficient removal of so3 from flue gas. The investigation was carried out in a fixed-bed reactor, employing Florida pebble rock. Investigations of effects of bed temperature, gas flow, SO3 concentration, and reaction time on SO3 pickup and conversion of P ~ 0 3 to available form showed that SO3 in flue gases can be removed by and react with phosphate rock to produce a product suggestive of fertilizer-grade normal superphosphate. About 87y0 conversion of total P z O present ~ in the starting material to available form was achieved, yielding a product which contained 18.6% by weight of available PzOS. The experimental data were correlated empirically and presented graphically. Application of the data to reactor sizing is illustrated, using a moving-bed reactor as an example.
B . C. Kim and ,I.E. Flinn, Battelle Memorial Institute, Columbus, Ohio 43201 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8, 400-407 (1969) INTERACTION PARAMETERS FOR KAY'S PSEUDOCRITICAL TEMPERATURE
Empirical binary interaction parameters for Kay's pseudocritical temperature are presented for a wide variety of pairs of substances. The interaction terms lead to more reliable pseudocritical temperatures, which, in turn, may be used to define pseudocritical pressures according to the scheme recommended by Prausnitz and Gunn. The success of the proposed pseudocritical rule is illustrated for the calculation of density and enthalpy in several binary systems. The method may be readily extended to multicomponent systems.
H . E. Barner aad C. W . Quinlan, M . W . Kellogg Co., Piscataway, N . J . 08854 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8, 407-412 (1969) ESTIMATION OF PARAMETERS FOR THE NRTL EQUATION FOR EXCESS GIBBS ENERGIES OF STRONGLY NONIDEAL LIQUID MIXTURES
IND.END.CHEM.PROCESS DESIGN DEVELOP. 8, 383-385 (1969)
Charts are given for estimating NRTL (nonrandom, two-liquid) parameters from limiting activity coefficient data or from mutual solubilities. Calculated and experimental results are given for binary and ternary systems.
KINETICS AND DYNAMICS OF CATALYTIC CRACKING SELECTIVITY IN FIXED-BED REACTORS
Henri Renon and J . M . Prausnitr, University of California, Berkeley, Cahy. 94720 IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8, 413-419 (1969)
The effect of time-averaging the product from a fixed-bed catalytic cracking reactor has been compared to a kinetic-catalyst aging model of the conversion and gasoline selectivity. Time-averaging has a profound smoothing effect on the selectivity behavior of rapidly decaying catalysts. Selectivity behavior of catalysts in fixed beds may rank differently compared to fluid- or moving-bed reactors, depending on the rate of decay,
HIGH-TEMPERATURE PYROLYSIS OF ISOBUTENE
The product distribution of the high-temperature pyrolysis of isobutene was experimentally determined. The decomposition can be represented as a system of simultaneous and/or consecutive reactions.
V . W . Weekman, Jr., Mobil Research and Development Corp., Paulsboro, N . J . 08066
Karl Schiigerl, J . Hafpel, and S. Levinson, New York University, Bronx, N . Y .
IND.ENG.CHEM.PROCESS DEVELOP. 8, 385-391 (1969)
IND.ENG.CHEM.PROCESS DESIGN DEVELOP. 8, 419-431 (1969)
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INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
