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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01 Apr 1973TL;DR: In this paper, the optimum solvent ratio in countercurrent distribution and chromatography may be expressed as V = VU/VL = (KD1 KDπ ) −½.
Abstract: It is commonly believed that the optimum solvent ratio in countercurrent distribution and chromatography may be expressed as V = VU/VL = (KD1 KDπ ) −½. Here VU and VL are the volumes of mobile and stationary phases. This expression, proposed by Bush and Densen and widely accepted, leads to optimum separations only under special conditions. Under most commonly-encountered situations in chromatographic and countercurrent systems, better separations may be achieved by reducing V to the lowest practicable level. Measures of separation effectiveness include resolution, extent of separation, total percent impurity, and quantity factor, the latter two of which are herein developed. Computer simulation is used for testing existing separation parameters and developing new ones on a rational and scientific basis.
3 citations
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TL;DR: In this article, a comparison of cocurrent and countercurrent modes of operation for an industrial wastewater treatment loop of an industrial urea plant has been carried out, where a thermal hydrolyzer is used for urea decomposition, and two desorbers are used for the removal of ammonia and carbon dioxide.
Abstract: In this work, a comparison of cocurrent and countercurrent modes of operation for an industrial wastewater treatment loop of an industrial urea plant has been carried out. In both modes of operation, a loop with a thermal hydrolyzer is used for urea decomposition, and two desorbers are used for the removal of ammonia and carbon dioxide. In the proposed model, the extended electrolytic UNIQUAC equation is used to describe the nonideality of the liquid phase of the NH3−CO2−H2O−urea system, and the perturbed-hard-sphere (PHS) equation of state is applied to predict the vapor fugacity coefficients. Also, the urea hydrolysis reactors are divided into several continuously stirred tank reactors (CSTRs) and the equilibrium-stage model is applied for modeling of both kinds of reactors and of the desorbers. The simulation results show that countercurrent mode of operation is necessary to achieve new environmental standards and complete treatment. The data predicted using the model were consistent with available pla...
3 citations
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TL;DR: In this article, a countercurrent flow limitation model incorporated into the RELAP5/MOD3 system transient analysis code is presented, which is implemented in a manner similar to the relAP5 chocking model.
Abstract: This paper reports on a countercurrent flow limitation model incorporated into the RELAP5/MOD3 system transient analysis code. The model is implemented in a manner similar to the RELAP5 chocking model. Simulations using air/water flooding test problem demonstrate the ability of the code to significantly improve its comparison to data when a flooding correlation is used.
3 citations
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19 Oct 1978
TL;DR: In this paper, the authors propose to separate butanediol from an aqueous solution thereof, efficiently with a small amount of heat by combining countercurrent extraction with recycling using a specific extractant and distillation.
Abstract: PURPOSE:To separate butanediol from an aqueous solution thereof, efficiently with a small amount of heat by combining countercurrent extraction with recycling using a specific extractant and distillation.
3 citations
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24 Oct 1974
TL;DR: In this article, a circular oil or gas fired kiln has inlets for hot gases and unburnt gases with excess air at the top of the shaft and a cooling air inlet at the bottom.
Abstract: Annular oil or gas fired kiln has inlets for hot gases and unburnt gases with excess air at the top of the shaft and a cooling air inlet at the bottom. The gases exit through a central column after meeting in the hot zone. The gases burn before entering the charge so avoiding inadequate burning of charge around the perimeter of the shaft as experienced in fully countercurrent kilns.
3 citations