Showing papers in "Chemical Engineering in 1959"

Liquid Phase Mass Transfer in Wetted-Wall Columns

Abstract: This work was undertaken with a view to obtaining a general correlation for liquid phase mass transfer in wetted-wall columns. Studies were made on the absorption of pure solute gases by various solvents in columns of varied dimensions. The column dimensions, the systems employed and the ranges of the variables covered are given in Table 1.It was observed that the gas rate had no effect on the values of HL when the ReG was below 7, 000 or so, as shown in Fig. 3, and the difference obscrved by Emmert and Pigford4) between the HL valucs for absorption and those for desorption could not be noticed.The plots of HL vs. Re on logarithmic coordinates showed two distinctly different regions, A and B, as seen in Figs. 4-10. In region A, the values of HL varied with Re1.0 Sc0.5 and (μ/ρ)2/3 but were independent of z and σ. In region B, the HL values were proportional to Re0.5 Sc0.38, (μ/ρ)0.59, z0.12and σ0.15The data we e correlated with Eqs. 12 and 14, for region A and region B. The agreements of the data with the equations were good, as seen in Figs. 13, 14 and 15.

Flow Patterns of Liquid in a Cylindrical Mixing Vessel without Baffles

Abstract: The velocity distribution of liquid in a cylindrical mixing vessel with flat-plate-baffles like those commonly used was measured by the method similar to the one adopted for the agitator without baffles.1)Some of the experimental results are shown in Figs. 3, 4, 5, 6, 7, 8 and 9.Variations of the liquid velocity distributions caused by the baffle-plates inserted in the agitated vessel are shown in Fig. 10. Obviously, the insertion of baffle-plates reduces the circulating flow round the impeller axis (the circumferential component υt of liquid velocity) and promotes the circulation flow in the vertical direction (caused by the discharge flow from the tip of the impeller).The discharging performance of various impellers is represented by the ratio NPB/Nq1, which is a dimensionless factor corresponding to the relative power required for a unit quantity discharge. The ratios for various impellers are listed in Table 3 together with those in the non-baffled condition. It is to be noted that, in spite of a considerable increase in Nq1, the circulation efficiency of agitators is lowered by the insertion of baffle-plates.Furthermore, the power consumption in the neighbourhood of the impeller (NPimp) was calculated and compared with that consumed in the outer region of the vessel (ΔNP) as shown in Table 4.It may be concluded from above that the improvement in the circulating capacity can be accomplished to a certain extent by a proper design of baffle-plates.

Heat transfer to moving fluids

Abstract: A review is presented on methods of calculating heat transfer to moving fluids. Correlations are given for heat transfer coefiicients for fluids undergoing no change of phase, both inside and outside a conduit. Various resistances encountered in convective heat transfer are given. The use of dimensional analysis to correlate data is discussed, with correlations for low Reynolds numbers. Film coefficients for phase changes are discussed. (C.J.G.)

The Rate Expression of High Pressure Ammonia Synthesis in Which Industrial Iron Catalyst is Employed.

Abstract: As one of the rate expressions of high pressure ammonia synthesis in which industrial iron catalyst is employed, Temkin's Eqs. (1) and (2) are well known, but neither of them satisfy the data published by other investigators. This has been pointed out by Emmett, Uchida, Comings and others.The authors propose here some rate expressions, Eqs. (10) and (11) which they have obtained after examining all the data available. Eq. (10) is correspondent to the case where the rate-determining step is the dissociated adsorption of nitrogen molecule and the active site of catalyst is partly covered with atomic nitrogen, viz., in the Langmuir type adsorption.Eq. (10) is for the data of doubly or triply promoted catalyst (Cf. Fig. 1), while Eqs. (14) and (15) are for the singly promoted (by Al2O3) catalyst. Eq. (10) is found to be of great practical use, because the constant Ka remains constant, regardless of the variety of temperature and the kinds of catalysts employed.

Experimental Studies on the Pressure Drop Characteristics of Fiber Mats

Abstract: By using beds of glass fiber with adiameter of 4-270μ as shown in Table 1, we investigated the various pressure drop characteristics and obtained the following results.(1) Pressure drops of the fiber mats decrease with the reduction of the area ratio Ai/A0, i.c. area ratio of masked face area to initial face area of the fiber mat. And the pressure drop Δpf changes with filter thickness L or fiber diameter Df (Figs. 5, 6, 7 & 8). (2) From the definition of a drag coefficient of a fiber mat, the experimental drag coefficient CD, were obtained, and Correlated with Reynolds number NRe. (Fig. 9) The results are represented by the empirical Eq. (5) or (6).In case 10-3 NRe 1.5×1010-3CDe=0.6+4.7/√NRe+11NRe Eq. (5)(3) In Fig. 9, the curved line shows the vaLues calculated from Eq. (5), which are in agreement with the experimental data. Comparison was made between these values and those obtained from other investigators' equations, and the Iberalls' equation was found to be in agreement with ours in case NRe 1. When NRe 1, however, all the values obtained from other investigators' equations deviated from the experimental data.(4) The pressure drops of the fiber mats were proportional to (1-e)m in our experiments (Eq. 7). When this relation is introduced in to Eq. (4), in the place of (1-e), we may call it a modifid drag coefficient CDm. The correlations of CDm vs. NRe can be given by Fig. 12 in the same way as by Fig. 9, and the experimental data fall exactly on the straight line when NRe 1(CDm∝NRe-1), and they show tendencies similar to frictional factors of acircular pipe for the turbulent region when NRe 1 (Eq. 8).

Fused salt thermal conductivity

Abstract: Calculations, using either Rao's or Osida's equation, of the atomic portion of the total thermal conductivity for various fused salts are presented in tabular form. (C.J.G.)

Studies on the Pulsed Plate Column

Abstract: Variations of the concentration of the continuous phase in the pulsed plate column were measured in the experiments on the extraction of acetic acid from methylisobutyl ketone by means of water.In this column, the longitudinal mixing was very intensive. The variation of the concentration was approximated on the assumption that the backmixing diffusivity was constant throughout the column.Capacity coefficient eliminated from the effect of the longitudinal mixing and the backmixing diffusivity were calculated in the present work.It was concluded that the decrease of extraction efficiency in the lower range of operating condition was caused by the longitudinal mixing.

Influence of Particle Size of Powder on Mixing Degree and Mixing Speed in Several Types of Mixers

Abstract: In our previous paper we reported the influence of physical properties of powder on the mixingdegree and mixing speed in several types of mixers.The present paper deals with our continued studies on the influence of particle size of powder on the above-mentioned factors observed in several types of mixers.The experiments were made by mixing three kinds of dry powder system: Na2CO3-sand system, having the particle-size distributions shown in Table 1, such as (1) the kind in which both the sample powders have the same size range and comparatively narrow size distributions, (2) another kind in which both the powders have the same size range and wide size distributions, and (3) the other kind in which both the powders have different size range and comparatively narrow distributions.What we made clear by our researches were:1) The optimum rotational speed of each mixer Nop was increased as the particle diameter (mean) increased, as shown in Fig. 3 and Eq. (4). The optimum volumes of powder to be charged were almost independent of the particle size in all experiments as shown in Fig. 2-a.2) The influence of particle size might be divided into two kinds:a) The influence observed when both the components had the same size.b) The influence observed when both the components had different size.In a), when the particle size of the powder was comparatively larger, the values of σs became larger, due to the median diameter of the distribution size as shown in Fig. 4.But, in b), as the particle size-ratio of the two components was increased, it became more and more difficult to obtain an intimate mixture, as shown in Figs. 6 and 7.

Drying Process Analysis of the Decreasing Drying Rate Period of Granular and Powder Material

Abstract: I. On the stational drying conditions:The drying rate curves for various materials and methods from which Eq. 1 is derived are shown in Figs. 1-4. It is clear from these that the decreasing drying rate of granular material is proportional to the water content of the material. The heat transfer between air and material is shown by Eq. (2). When the temp. gradient of the material is negligibly small, Eq. (3) is obtained. As shown in Figs. 5 and 6, the temp. gradient can be neglected for the granular material whose diameter is below 2-3mm. Eq. (4) derived from Eqs. (1) and (3) may be solved numerially, e.g., by Runge-Kutta's method. When the sensible heat of water (wc·cw) contained in the material is small as compared with the specific heat of the dried material and rm≅rw, Eq. (5) can be solved analytically:(6)In case (wc·cw) has a value comparable to the specific heat of the material, Fcrw/(c+cww )(t-tw)>>1 and rm≅rw, the following approximate equation, Eq. (8), can be obtained.(8)Eqs. (6) and (8) give the relation between tm and w.II. On the unsteady drying conditions:The unsteady drying which takes place in a continuous (parallel or counter current) dryer, such as a rotary, pneumatic conveying, spary or fluidized-bed dryer, can be presented by Eqs. (9)-(12). From these are derived Eqs. (13) and (14), whose solutions show the relations among t, tm and w in the dryer.These equations could be solved numerially. The calculated examples are shown in Table 1 and Figs. 9 and 10.The drying rate and the drying time in the continuous adiabatic dryer which can be easily calculated by using these relations may help to decide the dryer volume.The application of this calculation method to the dryer design would be expatiated upon in our report.

On the Non-Newtonian Laminar Flow in the Region near the Entrance of a Circular Pipe

Abstract: According to Prandtl's suggestion, the author calculated the velocity distribution and the pressure gradient of the non-Newtonian laminar flow in the region near the entrance of a circular pipe. The results are summarized as follows:1) Though the inlet length for the Newtonian flow, when n=1, was not in agreement with the results of the author's calculation, the change in the inlet length for the non-Newtonian flow, when the values of n were varied, could be roughly estimated as shown in Fig. 3.2) The pressure loss in the Newtonian flow, when n=1, was in good agreement with the results of the author's calculation. Therefore, on the assumption that the pressure loss in the non-Newtonian flow with different values of n would be in good agreement with the experimental results, too, the correction of the pressure loss Δq for different values of n was made as shown in Fig. 5

Fast, convenient approach to sizing heat exchangers

Abstract: BS>A quick technique for heat transfer calculations, known as the E-NTU methods is presented. Basically the method involves expressing heat transfer effectiveness or efficiency E in terms of thermal capacity of the two fluids and a dimensionless term called Number of Transfer Units NTU. (W. L. H.)

On the Mechanism of Ball Mill Grinding

Abstract: In the previous report4), we suggested that the grindability or the rate of grinding of particles was closely connected with the size distribution pattern of the ground material, which ranged from the bulk crushing to the surface grinding. We assumed, also, that the size distribution of the ground material was affected by the strength of grinding force.This paper is intended to verify the above-mentioned assumption by means of the ball-mill grinding, which is the most general operation pattern comprizing factors we can easily vary.Silica balls with four different diameters (and naturally of different weights) and sintercorund balls with one diameter were respectively employed at various rotational speeds of the mill. To investigate the results of the experiment, we assumed the characteristic number of β, which indicates a characteristic of the size distribution relative to the ratio of cumulative weight percent of the coarse part (Y(r)to that of the fine part (Y(f)). (Cf. Fig. 4).When the ball weight or the speed of rotation increased, (or the grinding force increased), β also increased as shown in Eq. 4-2 and Figs. 8 and 9. The values of kβ and kx were closely related to the particle diameters, viz., when the fed particles were small, the effect of grinding force was small.From this we may conclude that in fine grinding, the weight of a ball does not count much.It was observed that in general the grinding rate of particle (X) was determined by the grindability of particle (Γ) and the mechanical efficiency of grinding (ηm), which is the probability of ball impact or that of other grinding forces. Therefore, in fine grinding, Γ becomes negligible, and ηm essential.Upon this, we assumed that ηm (or impact number per one rotation of the mill) was constant irrespective of the speed of rotation of the mill, and obtained by experiment the relative values of ηm as shown in Fig. 10.Furthermore, according to H.E. Rose's suggestion9), from the supposed contact area of a couple of balls and probability of impact of balls in the mill., we derived relative efficiency of ball impact, as shown in Eq. 5-13, and ascertained the experimental results and Eq. 5-13, as shown in Fig. 17.

Mass Transfer into a Liquid Film Flowing over a Packing Piece

Abstract: The main objectives of this work were, first to see whether an unsteady-state diffusion theory was applicable to mass transfer into a liquid film flowing over the surface of a packing piece such as a Raschig ring or a Berl saddle, and, second, to obtain a general correlation for liquid phase mass transfer coefficients of these packings.Absorption of pure carbon dioxide by three solvents, water, methanol and n-butanol, were carried out in a column, where single pieces of Raschig rings or Berl saddles were located as shown in Fig. 1. Figs. 2 and 3 show the values of HL for a Raschig ring in case θ is 45°. When the values of (HL/z)·(Ga1/6/Sc1/2) are calculated from these data and plotted against Re as shown in Figs. 4 and 5, the data points for all runs come on a single line as represented by Eq. (5). These results indicate that mass transfer into a liquid film flowing over the packing pieces closely follows predictions based on the unsteady-state diffusion theory. Figs. 6, 7 and 8, similar to Figs. 4 and 5, show the results given with a Raschig ring (θ=90°), with a short wetted-wall column corresponding to a Raschig ring (θ=0°) and with a Berl saddle (θ=45°), respectively. The best lines through the data in these figures are expressed by Eqs. (6), (7) and (8), respectively. Taking the variation of HL with θ into account, Eqs. (19) and (20), giving the average values of HL for single pieces of Raschig rings and Berl saddles, have been obtained.In order to determine the effect of Schmidt number on HL for packed columns, additional experiments on the absorption of pure solute gases, hydrogen, oxygen and carbon dioxide, by water were carried out in a 7.0cm column packed with 15mm Raschig rings. Experimental results indicate that the values of HL vary as the 1/2 power of the Schmidt number, in agreement with the unsteadystate diffusion theory.

New alloy n joins hastelloy family

Abstract: The development and properties of a new nickelmolybdenum alloy for use as a container material for fused fluorides containing uranium are discussed. Tests prove that the alloy is resistant to corrosion from fluoride salts, oxidation in air, and elevated temperatures. (J.H.M.)

Capryl pyrophosphate ester extracts uranium from wet-process phosphoric acid

Abstract: Techniques using a capryl-pyrophosphate ester solvent for recovering uranium from impurity-laden wetprocess phosphoric acid are discussed. A flowsheet for the complete process is given. (J.H.M.)

Behaviours of Slurry Mixtures at Constant-Pressure Fiitration

Abstract: The filtration behaviours of the slurry mixtures consisting of two components with known filtration charactcristics, i.e., Hongkong Kaolins "Pink" and "Dark-Yellow, " were investigated. The equilibrium porosities eX, mass ratios of wet cake to dry cake mX', average specific resistances of cakes α'f·s·X, average effective specific surface areas Ss·X and Ruth's coefficients K'20·f·X of the slurry mixtures were studied in order to correlate them with those of the pure components. The characteristics of the two constituents are shown in Table 1 as well as in our former report3) Brief summaries of the results are as follows:(i) Average effective specific surface areas calculated from Eq. (6) were found to be not additive, on the volume basis, as shown in Fig. 7. In this case, (√k·S2s·X)P was always larger than (√k·S2s·X)l·P by about 11.8-0.1%, when the range for s=0.1-0.3 and P=500-9000[gr/cmcm2].(ii) The same tendency as in (i) was noticed of the results of permeability experiments as revealed in Fig. 3.(iii) Average specific resistance, α'f·s·X and K'20·f·X vs. X were rather complicated as shown in Figs. 8 and 9, respectively.(iv) (√k·S2s·X)P was nearly equal to (√k·S2s·X)l'P when the range of s≥0.2 and P=1000-9000 [gr/cmcm2]. The difference between them was less than 7.4%.(v) Due to the fact that the equilibrium porosities and mass ratios of wet cake to dry cake of each component were approximately equal, as shown in Table 1, the equilibrium porosity eX showed a linear relation against X' as represented by Eq. (1) and Fig. 2. Also mX vs. X was linear as represented by Eq. (2).

Mass Transfer into Liquid Film Flowing over Spheres

Abstract: This work was undertaken to clarify the mechanism of mass transfer into a liquid film flowing over the surface of a sphere and to see whether liquid is mixed completely or not at the points of juncture between the spheres connected in a vertical row. Experiments were performed on the absorption of pure carbon dioxide by water with and without a wetting agent, in columns containing 1, 3 and 5 spheres, respectively.Experimental data for single sphere are shown in Figs. 3 and 4, and those for multiple sphere in Fig. 6, as the plot of the HL values against the Reynolds number on logarithmic coordinates. Results with single sphere were in good agreement with the theoretical equation based on the assumptions of unsteady-state diffusion and parabolic velocity distribution in the liquid film, as shown in Fig. 5. The addition of a wetting agent caused no change in the absorption rate in the case of single sphere, and the HL values for both the runs with and without agent were the same.Fig. 7 shows the correlation among the results obtained with multiple sphere, when pure water was used as a solvent. Good agreement was obtained between the data and the theoretical equation, derived from the assumption that the mixing of the liquid was complete at the points of juncture between the spheres. Fig. 8 shows a similar plot of the data obtained by Yoshida and Koyanagi.7)When a wetting agent was added to water, the values of HL were higher than those for pure water and increased with the number of spheres, as shown in Fig. 9. The data obtained by authors and those by Lynn, Straatemeier and Kramers5) were in fairly good agreement with the theoretical equation based on the assumption that there was no mixing of the liquid as it flew from one sphere to the next.

A Method for Analyzing the Vertical Flow of Liquid-Solid Systems

Abstract: A graphical method for analyzing liquid-solid systems and an experimental process for obtaining basic data for said analysis to be applicable to one dimensional vertical flow are presented.1) The graphical method proposed by Kynch (1952) and Lighthill Whitham (1955) for kinematic waves have been modified, taking into account the influence which the liquid flow rate and the mean space-velocity of solid particles have on each other. There are given also several examples as are of use in the practical solution of this kind of problems.2) As a new experimental process for obtaining a flow-concentration curve on which the graphical analysis is based, the liquid-fluidized-bed method is investigated. Experimental examinations in batch and continuous settling have proved that the method holds good.

Effect of Rippling on Liquid Phase Mass Transfer in Wetted-Wall Columns

Abstract: In wetted wall columns, pure carbon dioxide was absorbed in water containing surface active agent.With the increase in the concentration of the agent, rippling on the surface of the liquid film decreased. When the concentration of the agent exceeded a certain value, rippling almost disappeared. The effect of this change in rippling on the rate of mass transfer from gas to liquid across the interface was studied, and the results obtained are shown in Fig. 2 and 3, in which HL is plotted versus Re on logarithmic coordinates.From these results, it appears that with the decrease in rippling, the disturbance caused by the mixing action of ripples decreases and the flow pattern of the liquid film in the pseudo-stream line flow approaches that of the liquid film in the true viscous flow.The results obtained by the present author and the previous investigators3, 6) for the case when there was no rippling, are shown in Figs. 5 and 6, respectively, as the plots of HL/z versus l/p on logarithmic coordinates. The best line through the data can be expressed by Eq. (8). This experimental line lies above the theoretical line based on the unsteady-state diffusion theory derived by Pigford9. The discrepancy between the theory and the experiment is probably due to the difference between the assumed and actual flow conditions for the liquid film.

Process Optimum Condition for Gas-Solid Catalytic Reaction Process in Fixed-Bed

Abstract: For the fixed-bed reactors such as adiabatic multistage reactors, autothermic reactors and externally cooled reactors, the authors studied on the process optimum condition. which means the condition where the necessary amount of catalyst in VR/F is minimized when the conversion is specified.Considering the reaction whose rate at a given composition of the reaction mixture have maximum at a temperature, as in the ammonia synthesis and the catalytic oxidation in sulphur dioxide, the authors extended Konoki's treatment for the adiabatic multistage reactor3, 4) in whose operation maximum temperature is fixed, into the more general form, Eq. (18) through Eq. (21). These results were sucessfully applied to the sulphur dioxide convertor of adiabatic 3-stage.For the autothermic process with two flow paths (Fig. 5), the authors using the simpler design equation (30) instead of Eq.(24), proposed a graphical method of solution based on Picard's method.10) By this method we can easily determine optimum Γ and T10 As an example the authors showed the result of trial and error for the determination of T and T10 for the autothermic ammonia synthesis process. The basic equations (32) for the externally cooled reactor can be also reduced to the simpler form, Eq. (35), and so the same method above described will be employed.

Kinetic Studies on the Preparation of Maleic Anhydride by Catalytic Air Oxidation of Cyclopentadiene

Abstract: Experimental rate equations for reactor design have been studied. Rates of the reactions were measured over a range of concentration of cyclopentadiene, 0.2-0.4 mole%, reaction temperature, 380-435°C, flow rate of gas, 1-2m3/hr, and volume of V2O5MoO3 catalyst, 10-30cc, by means of the reactor shown in Fig. 1.Experimental results can be expressed by the equations (2), (3) and (4).From the experimental results, it is concluded that cyclopentadiene is oxidized by two simultaneous reactions taking place at the temperatures between 380 and 435°C, the first one giving maleic anhydride and the second one causing complete combustion, the ratio k1/k2 depending only on the reaction temperatures.Calculated and observed mole fractions of the cyclopentadiene used as against 2/N are plotted in Figs. 9 and 10.The longitudinal temperature profile of the catalyst bed in the tubular reactor as calculated by means of the rate equations and the heat balance equation agrees well with the observed one as shown in Fig. 11.A three-stage adiabatic converter with intercooler between catalyst beds is designed by applying the rate equations. The influence of the catalyst-bed length on the calculated reaction temperature and yield of maleic anhydride is shown in Fig. 12.

Theoretical Temperature Distribution in Packed Bed

Abstract: In a cylindrical packed tube heated under the uniform wall temperature, the partial differential equation for the temperature in the steady state is given by Eq. (1).However, when no chemical reaction takes place, Eq. (1)reduces to Eq. (1') with the assumption thatCp G is uniform over the cross section and ke, r and ke, z are uniform within the bed.The solutions can be obtained by applying the finite Hankel transform with respect to. In case of semi-infinite cylinder, Eq. (2) representing the boundary condition at the bed inlet and Eq. (3) representing the boundary condition at the inside wall surface, are applied to Eq. (1'). The solution is given by Eqs. (6) and (7), where ξi is the root of Eq. (4). On the other hand, in case of finite cylinder, Eq. (10) which stands for the bed outlet condition should be employed together with Eqs. (2) and (3), in solving Eq. (1'). The solution is shown by Eqs. (6) and (11).The temperature at the center axis of the packed tube tc and the mixed-mean temperature over the cross section tm are represented by Eqs. (8) and (9), respectively, which are modified forms of Eq. (6).However the solution for the temperature distribution in the finite cylinder will be valid for any value of δ, Eq. (11) is nearly equal to Eq. (7) when δ is less than 30 or so.The value of δ is smaller than 10 for the usual packed beds14), consequently, it may be concluded that Eqs. (6) and (7) are applicable enough, regarding the packed bed as the semi-infinite cylinder.In case the flow-rate is relatively high, k becomes small, and then Eqs. (6) and (7) are nearly equal to Eq. (13) obtained by Maeda et al4) and Marshall et al1), in which equation the axial heat conduction is neglected. But it should be pointed that Eqs. (6) and (7) serve as a good solution for the low flow-rate range, because k is not so small in this range.When chemical reaction approximated by q=q0·exp[-αl] takes place, the temperature distribution is reprerented by Eq. (14), assuming the packed bed as the semi-infinite cylinder.

On the Over-all Effective Reaction Rate of Gas-Solid Catalytic Reaction Process

Abstract: It is well known that, in the high temperature region, the diffusional resistances within the boundary film and that within the pores of catalyst pellet have an important effect on the overall effective reaction rate. In reactor design, it is essential to analyze the experimental data and to distinguish the effect of diffusion from the chemical reaction rate so as to predict the over-all effective reaction rate for the given industrial conditions.Previously, Kubota and Shindo5) presented a method for calculating effectiveness factor of the porous catalyst, which is applicable to any reaction but which involves considerable complicated computations.In this paper, the authors present a new method for calculating effectiveness factor, based on the approximation of reaction rate to a kind of first-order reaction as expressed by Eq. (6) or (7). When this method was applied to ammonia synthesis, whose rate was expressed by Eq. (13) and which was far from the first-order reaction, the value of Ef' obtained was found to be a very good approximation to the value of Ef obtained by the previous method (Fig. 2).Other proposals the authors make in this paper are (i) a general analytical procedure for predicting the effective reaction rate by taking into account the diffusional resistances within the boundary film and that within pores of catalyst pellet, and (ii) two other methods for estimating the chemical reaction rate from the experimental data, by taking into account the above-mentioned diffusional resistances. Of these two methods, the first one is applicable when veA (pAG) can be obtained from the reaction, viz. when the reaction is carried on in a differential reactor, and the second one is applicable when veA (pAG) cannot be obtained directly from the experiment, viz., when the reaction is carried on in an integral reactor. When the latter was applied to the ammonia synthesis data, obtained by one of the authors4), great difference was found in the range of above 475°C or so, between the apparent values of reaction rate constant and their corrected values given according to this procedure.

Effective Thermal Conductivities of Wetted Packed Beds

Abstract: Mesurements of effective thermal conductivities of wetted packed beds were made by using an unsteady heating cell.Packings used were of sand, lead shots or crushed glass. Either castor oil or water was used as a wetting liquid.As the result, an experimental formula, Eq. (5), for effective thermal conductivities, was obtained.

Chemical engineering unit operations help solve atomic power plant problems

Abstract: Problems encountered by chemical engineers in design of the Indian Point nuclear power plant are choice of materials of construction to resist corrosion and radioactivity, handling and disposing of hydrogen and oxygen (cooling-water- decomposition products due to radioactivity), preparation of ultra-pure feed water for the reactor coolant cycle, and handling of solid, liquid, and gaseous radioactive wastes. (C.J.G.)

Absorption of Carbon-Dioxide by Various Solvents in Packed Towers

Abstract: In order to study the dependence of liquid phase capacity coefficient in a packed tower on the physical properties of the absorption system, experiments were conducted on the purely physical absorption of carbon-dioxide by various solvents. As the solvents, ethyl-alcohol, methyl-alcohol, water, benzene, decalin and carbon-tetrachloride were used.With all the solvents, the kLa vs. L curves had a critical point where the dependence of kLa on L showed a sudden change. The critical values of (L/μ) were correlated by Eq. (4') for all the solvents except water, for which the critical value (L/μ) was found to be equal to 1300. Experimental results ranging below these critical points are expressed by Eq. (5) while those above them are expressed by Eqs. (6) and (7).From Eqs. (5) and (6), the exponent of Schmidt number relating to (kLa/DL) was found to be approximately 1/2. This value agrees quite well with the results obtained by Sherwood and Holloway as well as those of our previous investigation6) and the prediction by Higbie.

Adsorption Equilibrium of Liquid Hydrocarbon Mixtures by Silica Gel or Activated Almina

Abstract: This article refers to the adsorption equilibrium of binary liquid hydrocarbon mixture, i.e. toluenen-hexane by silica gel or activated alumina, studied by means of the direct liquid contacting method. From the experimental data on the adsorption equilibrium were calculated the separation factor, α, in Eq. (1') and the volume of the liquid adsorbed by a gram of adsorbent or the volume of adsorbed phase, z, in Eq. (5).The results obtained were as follows:(1) z which was constant over the wide range of liquid concentration for each adsorbent was affected considerably by the preparation temperature.(2) α, a characteristic constant for each adsorbent, i.e., 14 for silica gel and 7.3 for activated alumina, was not affected by the preparation temperature.(3) x-y Diagrams calculated by using α in Eq. (1') was in good agreement with that calculated by using z in Eq. (4'), as shown in Fig. (6).

On the Law of Similarity of the Heat Transfer in Non-Newtonian Flow

Abstract: Although the studies on the heat transfer in non-Newtonian flow are increasing in recent years, the law of similarity of the heat transfer is not yet established. It is true that the previous investigators tried to find correlation between the experimental data on the heat transfer and various dimensionless numbers, but there is observed no consistency between them.In this paper, the author describes the law of similarity of the heat transfer in non-Newtonian flow which he has derived, using the fundamental equation. The results may be summarized as follows:(1) Pseudoplastic and dilatant fluid:(a) Natural ConvectionNu=f1(Gr, Pr2)(b) Forced convectionNu=f2(Re, Pr1):(2) Bingham fluid:(a) Natural convectionNu=f3(Gr, cGr, Pr, cPr)(b) Forced convectionNu=f4(Re, cRe, Pr, cPr)

Treating and disposing of radioactive wastes

Abstract: S>The problem of handling and storage of radioactive waste is discussed. The treatment of wastes by evaporation, fixation in solids precipitation ion exchange, and calcination is described. Ultimate disposal methods such as salt cavities deep wells and ocean burial are described. (W.L.H.)