Showing papers on "Countercurrent exchange published in 1979"

Simulated countercurrent sorption process employing ion exchange resins with backflushing

Abstract: A process for separating a selected component from a fluid mixture of components by employment of an ion exchange resin. Fluid flow is maintained through a column containing the adsorbent in at least three separation zones, an adsorption zone in which the selected component is adsorbed by the adsorbent, a purification zone and a desorption zone from which the selected component is displaced by a desorbent material. There is also a backflushing zone, upstream of either the feed or desorbent stream inlets, in which the direction of fluid flow is opposite the direction of flow through the three separation zones. The zones are periodically shifted through the column by advancing the input and output streams. The backflushing serves to decrease the density of the resin bed thereby controlling the pressure drop developed through that bed when it is in service as part of a separation zone. The ion exchange resin particularly suitable for the invention is an alkali metal salt of a nuclearly sulfonated styrene-cation exchange resin containing a cross-linking agent. The process of the invention is particularly suitable for the separation of a saccharide from an aqueous solution of saccharides.

Mass transfer in regular arrays of hollow fibers in countercurrent dialysis

Abstract: The concentration profiles in a countercurrent hollow fiber bundle mass exchanger dialyzer is derived, assuming a uniform distribution of fibers in the dialyzer shell. Mass transfer coefficients are obtained as a function of fiber packing density, membrane thickness, membrane material, and solute type.

The simulation of binary adsorption in continuous countercurrent operation and a comparison with other operating modes

Abstract: Simulation studies are presented of three different modes of operating a two-component adsorption system. The efficiency with which an activated carbon adsorbent is utilized is compared for a single fixed bed, a periodic countercurrent system in which the adsorbent is equally distributed over two, four, and six beds and a continuous countercurrent system. The carbon utilization in the single fixed bed was shown to be one third to one half of that in a continuous countercurrent adsorber of the same length, whereas the periodic countercurrent system achieved a utilization of 79 to 98% of that in the continuous system. The mathematical models used to describe the three different modes of column operation include the effects of axial diffusion in the columns, mass transfer resistance in the boundary layer surrounding each particle, and fluid diffusion within the porous particles.

Staged turbulent bed retorting process

Abstract: A continuous process is disclosed for the retorting of shale and other similar hydrocarbon-containing solids of a broad particle size distribution in which the solids to be retorted are introduced into an upper portion of an elongated vessel with a solid heat transfer material at an elevated temperature. The hydrocarbon-containing solids and heat transfer material, a portion of each being fluidized, pass downwardly through the retort under substantially plug-flow conditions, countercurrent to an upwardly flowing stripping gas. Retorted solids and heat transfer material are withdrawn from the bottom of the retort vessel and a product stream of hydrocarbon vapors mixed with stripping gas is recovered overhead.

Continuous countercurrent fluid-solids contacting process stabilized by a magnetic field

Abstract: The present invention relates to a process for continuous countercurrent contacting with magnetically stabilized fluidized beds. More particularly, the invention relates to the operation of a magnetically stabilized bed with continuous solid addition and removal. The bed particles which include a magnetizable component are stabilized against gas by-passing and solids back-mixing (except possibly for the flow or movement of the solids near entrance or exit ports or near fluid injection zones) during countercurrent contacting by the use of an applied magnetic field. The process of the invention is particularly suited for carrying out separation processes. The use of the applied magnetic field in such processes enables one to use small size fluidizable, adsorbent particles without encountering high pressure drops. The small adsorbent particles having a magnetic component give faster transfer of the sorbed species from the contacting fluid than with larger adsorbent particles which allows for a closer approach to equilibrium.

Cascade multicomponent cooling method for liquefying natural gas

Abstract: A cooling arrangement to be used in liquefying natural gas and in similar applications and having an incorporated cascade circuit with a fractional condensation of a cooling medium and with separation of the phases of the cooling medium, has such a lay-out and is so operated that the warming-up of the expanded cooling medium in a countercurrent evaporative heat exchange and the warming-up of the expanded cooling medium in a countercurrent supercooling heat exchange are in parallel to one another. The separated gaseous phase of the cooling medium is cooled in the countercurrent evaporative heat exchange to be at least partially condensed. The countercurrent supercooling heat exchange and the countercurrent evaporative heat exchange are thermally segregated from one another.

Flooding in two-phase countercurrent flows. [PWR; BWR]

Abstract: An important problem in the safety analysis of light water nuclear reactors (LWRs) is the flooding phenomenon or the countercurrent flow limit, which may be encountered during the reflood process of the reactor, following a hypothetical loss-of-coolant accident (LOCA). The present work consists of an experimental and analytical study of an air-liquid/countercurrent flooding limits in a vertical tube. The analysis is based on interfacial instability and kinematic wave theory. The experiments include effects of fluid properties and entry geometry. The theoretical results can be adjusted to fit the data as well as available correlations (e.g., Wallis) by an appropriate choice of constants.

Reverse osmosis system

Abstract: The relative concentrations of solvent and solute in a solution are altered by a system which includes a cell having chambers separated by a membrane and a means for creating a pressure differential across the membrane A solution moves through an inlet means around the system and countercurrent and reflux flow and outlet means The cell may be formed of modular units in such a way as to effect a tapered configuration so that the flow rate is homogeneous around the system

Design Procedures for Solid-Liquid Extractors and the Effect of Hydrodynamic Instabilities on Extractor Performance

Abstract: A design method is proposed for countercurrent mass transfer cascades with crossflow stages, and unsteady operated fixed beds in a countercurrent arrangement. The separation performance of these cascades is calculated from mathematical models and compared with a purely countercurrent extractor. The models are based on simple equations describing mass transfer in a single stage fixed bed. The results are presented as concise correlations between the number of true and exterior apparent transfer units. Asymptotic values of the mass transfer coefficient for transient diffusion processes in cocurrent and countercurrent extractors are calculated for particles with simple geometry. Comparing the extraction efficiency calculated from the exact solutions of the diffusion equations and the values obtained from the asymptotic mass transfer coefficient shows that differences are small under normal operating conditions for countercurrent extraction. The use of the asymptotic values in design calculations is discussed. Due to the commonly observed viscosity and density gradients in the solvent phase, non-uniform flow of liquid through the layer of solids subjected to extraction can occur. Then some fraction of the solids is not efficiently contacted with the solvent. Experiments show that a concentration gradient rather than a concentration jump in the liquid flowing through an inert packing material reduces the effect of channelling. The effect of mass transfer between the packing and the surrounding liquid on flow stability is studied. The results indicate that channelling can reduce the extraction efficiency in solid-liquid extractors.

Simultaneous heat and mass transfer in turbulent gas streams in wetted-wall columns

Abstract: The effect of the gas and liquid flow rates on the gas-phase mass and heat transfer rates in turbulent gas streams in wetted-wall columns with cocurrent and countercurrent gas-liquid flow was studied. The experiments were carried out on the adiabatic vaporization of water into a turbulent air stream under both conditions of rippling and no rippling on the surface of the falling liquid film. The experimental results showed that the effect of the gas and liquid flow rates on the mass and heat transfer rates are in good agreement with the theoretical predictions and that the effect of the rippling on the mass and heat transfer rates can be neglected.

Process for the production of suspension or solution of cyanuric chloride in organic solvents (II)

Abstract: Suspension or solutions of cyanuric chloride in water containing organic solvents are prepared at high mixing velocities and low temperatures with resulting low degree of hydrolysis by introducing liquid cyanuric chloride through a nozzle in the upper portion of the mixing apparatus in countercurrent flow to upwardly flowing solvent introduced from at least one lower nozzle above a breast shaped constriction in the lower, open portion of the apparatus. In this way the chamber walls are always covered with an unbroken layer of liquid. The process can be carried out at normal, reduced or elevated pressure. At reduced pressure by evaporation of the solvent there is simultaneously a cooling of the system.

Column type countercurrent extraction method

Abstract: PURPOSE:To accomplish a stable operation for a long period of time with addition of gas from the bottom or a proper point of the column in a column type countercurrent extraction CONSTITUTION:In extraction of given components from material comprising a mixture of more than two kind of liquids through a counter-current of the material and a liquid solvent by means of a column, for example, methacrylic acid from a methacrylic acid solution obtained by a vapor phase contact oxidation reaction, using a mixed solvent of toluen and methyl methacrylate, operation is made as given below: A solution of methacrylic acid is fed through a pipe 4 while the afore-mentioned mixed solvent is fed through a pipe 5 At the same time, air is fed through a pipe 6 at a rate of 25 1 per hour An extraction liquid isdrained through a pipe 7 and a residual liquid through a pipe 8 Air is exhausted through a pipe 9 If necessary, nitrogen can be fed in place of air With such an arrangment, stable operation can be containued for a long period of time without accumulation of solid matter in the compartment

Dynamic modelling of countercurrent mass transfer processes

Abstract: By a mass transfer process is meant the movement of material components between two phases in contact under the influence of a composition difference. The simultaneous transfer of heat may also be involved, in some cases as a consequence of the mass transfer, but pure heat transfer processes will not be dealt with in this paper. Countercurrent transfer processes occur in two forms, the models for which are fundamentally different. Either the phases

Recovery of energy from geothermal brine and other hot water sources

Abstract: Process and system for recovery of energy from geothermal brines and other hot water sources, by direct contact heat exchange between the brine or hot water, and an immiscible working fluid, e.g. a hydrocarbon such as isobutane, in a heat exchange column, the brine or hot water therein flowing countercurrent to the flow of the working fluid. The column can be operated at subcritical, critical or above the critical pressure of the working fluid. Preferably, the column is provided with a plurality of sieve plates, and the heat exchange process and column, e.g. with respect to the design of such plates, number of plates employed, spacing between plates, area thereof, column diameter, and the like, are designed to achieve maximum throughput of brine or hot water and reduction in temperature differential at the respective stages or plates between the brine or hot water and the working fluid, and so minimize lost work and maximize efficiency, and minimize scale deposition from hot water containing fluid including salts, such as brine. Maximum throughput approximates minimum cost of electricity which can be produced by conversion of the recovered thermal energy to electrical energy.

Process for the production of suspensions or solutions of cyanuric chloride in water

Abstract: Suspension or solutions of cyanuric chloride in water are prepared at high mixing velocities and low temperatures with resulting low degree of hydrolysis by introducing liquid cyanuric chloride through a nozzle in the upper portion of the mixing apparatus in countercurrent flow to upwardly flowing water introduced from at least one lower nozzle above a breast shaped constriction in the lower, open portion of the apparatus. In this way the chamber walls are always covered with an unbroken layer of liquid. The process can be carried out at normal, reduced or elevated pressure. At reduced pressure by evaporation of the water there is simultaneously a cooling of the system.

Optimum axial flow taper in a countercurrent gas centrifuge

Abstract: The effect of an axially varying countercurrent circulation rate in a gas centrifuge on the efficiency factors, e/sub I/, the ideality efficiency, and e/sub C/, the circulation efficiency, is investigated and compared with the case in which the countercurrent circulation rate is constant throughout the centrifuge. The optimum variation of the centrifuge parameter m, which is a measure of the countercurrent circulation rate, as a function of axial position in the centrifuge is determined. It is shown that when the countercurrent circulation rate has its optimum value at every axial position in the centrifuge, the product of the efficiency factors, e/sub I/ x e/sub C/, can exceed 81 per cent, the nominal upper limit of the value of the product of the efficiency factors for a constant countercurrent circulation rate, and can be quite close to unity. This is illustrated by numerical examples based on a centrifuge previously described in the literature.

Gas separating and refining apparatus

Abstract: PURPOSE:To eliminate the adsorbent inactive part and to simplyfy the apparatus and also, to enable to reduce separating cost and refining cost, by flowing all sorts of gas countercurrent in relative moving direction of the adsorbent, at the rotary type mixed gas separating apparatus CONSTITUTION:The fluid F for desorption regeration (heating by the heater 12, if necessary), is sent to the desorption regereation zone of the rotor 2' relatively rotating against the stator 3' countercurrent moving direction of the rotor 2' and the exhaust fluid g is discharged with desorped component, at the rotary type mixed gas separating apparatus 1' having plural rooms packed adsorbent Next, a part of the cooling circulating gas C is sent in countercurrent direction as the sweeping gas D in the same way as the above mentioned process and the remaining fluid F is discharged and then, the circulation gas C is sent in countercurrent direction through the cooler 5 in cooling regulation zone Fully cooled adsorbent is prossessed a high adsorption power and easy adsorptive component in the raw material gas A sent in countercurrent direction, is adsorbed by the above adsorbent and the product gas B is made by difficult adsorptive component Thus, publicly known defect such as transferring the adsorption band for outlet side, is eliminated and one room of the adsorbent packing room is able to decrease and also, the apparatus is able to simplify

Shaftlike counterflow heat exchanger

Abstract: not available for EP0005469Abstract of corresponding document: US4245981The invention relates to a shaft-type countercurrent heat exchanger in which the uppermost part of the shaft is formed by a turbulence chamber which communicates with the underlying countercurrent chamber of the shaft through a central material outlet and several gas pipes opening tangentially into the turbulence chamber, thereby improving the thermal efficiency of the heat exchanger.

Yield and Purification in Multistage Countercurrent Separation Systems

Abstract: The approaches of Klinkenberg and Rony offer a route to a complete analytical solution of the problem of multistage countercurrent separation systems, but some revisions of their equations are required to express the true maximal separative power of multistage systems.

Shaft type countercurrent heat exchanger

Abstract: The invention relates to a shaft-type countercurrent heat exchanger in which the uppermost part of the shaft is formed by a turbulence chamber which communicates with the underlying countercurrent chamber of the shaft through a central material outlet and several gas pipes opening tangentially into the turbulence chamber, thereby improving the thermal efficiency of the heat exchanger.