Topic
Countercurrent exchange
About: Countercurrent exchange is a research topic. Over the lifetime, 2255 publications have been published within this topic receiving 28687 citations. The topic is also known as: Countercurrent exchange.
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TL;DR: In this paper, the separation power of ultrapurification of gases in cascades of the continuous membrane column type was calculated and the equation for the degree of separation of the extraction and enrichment section was obtained.
17 citations
Patent•
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02 Mar 1976
TL;DR: In this article, an ion exchange treating system where two or more exchanger or absorber vessels are connected in series, each vessel being filled with ion exchange resin leaving sufficient freeboard to allow for expansion of the medium.
Abstract: The invention is concerned with an ion exchange treating system wherein two or more exchanger or absorber vessels are connected in series, each vessel being filled with ion exchange resin leaving sufficient freeboard to allow for expansion of the medium. Each vessel is provided with an expansion chamber positioned above it and includes a conventional distribution system. The flow of liquids passing through the system is countercurrent with respect to the medium to be treated and the medium which regenerates the ion exchanger or absorber. Generally, the liquid to be treated enters the first vessel at the bottom, exiting from the top, entering the second vessel at the top and exiting therefrom at the bottom.
17 citations
TL;DR: In this article, the problem of multiphase nuclear reaction is addressed to achieve effective mass and heat transfer as well as a mixing pattern favorable to the particular process, and the various design and modeling aspects of these reactors have bee studied.
Abstract: Multiphase reactors involving gas, liquid, and solid phases have several important applications in the chemical industry, particularly in catalytic processes. Some of the well-known examples are: hydrogenation and oxidation of organic compounds, hydro-processing coal-derived and petroleum oils, Fischer-Tropsch synthesis, and methanation reactions. Due to the presence of three phases, the problem of reactor design is often important to achieve effective mass and heat transfer as well as a mixing pattern favorable to the particular process. The reactors are mainly of two types: (a) solid catalyst is suspended either by mechanical agitation or gas-induced agitation and (b) solid catalyst is in a fixed bed with concurrent or countercurrent feed of gas and liquid re-actants. The reactor types conventionally used in industry are: (a) mechanically agitated or bubble column slurry reactors and (b) trickle-bed or packed-bed bubble reactor. The various design and modeling aspects of these reactors have bee...
17 citations
TL;DR: In this article, a numerical model of a three-phase, direct-contact, spray-column heat exchanger has been developed, which is used to calculate performance information about this type of device and to compare, where possible, to experiments.
Abstract: A numerical model of a three-phase, direct-contact, spray-column heat exchanger has been developed. This model has been used to calculate performance information about this type of device and to compare, where possible, to experiments. General equations are defined for distance up the column using a physically based model for the local heat transfer. This model has been used to investigate a number of characteristics of these devices, such as temperature and holdup distributions through the column. A new formulation is given for a mixed, time-averaged temperature that may be representative of measurements taken with temperature transducers in direct-contact heat exchangers. Little has been given in the literature about quantitative variations of performance as a function of the key independent variables, and information on these aspects is presented here. Although the results presented are for a specific geometry (0.61 m diameter, 3 m active column height, evaporating pentane in 85/sup 0/ C water), the variations shown can give insights generally into the factors affecting performance in these devices. In virtually all cases examined here, extremely good comparisons are shown between predictions and measurements. Conclusions are drawn about the applicability of the model and the important effects demonstrated.
17 citations
TL;DR: In this paper, two different hydrogen redistribution strategies along a bubbling fluidized-bed hydrogen permselective membrane reactor have been compared, and a dynamic two-phase theory in the bubbling regime of fluidization was developed to model and compare two strategies from different points of view.
Abstract: In this work, two different hydrogen redistribution strategies along a bubbling fluidized-bed hydrogen permselective membrane reactor have been compared In the first strategy, fresh synthesis gas flows in the tube side of the fluidized-bed membrane reactor in cocurrent mode with reacting material in the shell side, so that more hydrogen is provided in the first segments of the reactor In the second strategy, fresh synthesis gas flows in the tube side of the fluidized-bed membrane reactor in countercurrent mode with reacting material in the shell side, so that more hydrogen is provided in the last segments of the reactor A dynamic two-phase theory in the bubbling regime of fluidization was developed to model and compare two strategies from different points of view Comparison between cocurrent and countercurrent modes of operation shows that the reactor in the countercurrent configuration operates with higher conversion of methanol, longer catalyst life, and higher carbon dioxide removal, whereas the re
17 citations