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.

Electroconcentration by using countercurrent due to pressurized flow and electrophoretic mobility

Abstract: A pressurized flow and countermigration, due to electrophoretic mobility of a solute, are used for sample concentration. An apparatus composed of two rooms with electrodes, connecting tubes, and a pump for aspirating the sample solution is proposed. The sample solution is aspirated into small tubes (1.5-mm i.d. and 15 mm long), over which a voltage is applied (300-800 V/cm). A solute of high electrophoretic mobility is found to be drawn back from the small tube. Naphthalene-sulfonic acids, herring DNA, and magnesium ions are concentrated 10-47 times under pressurized flow (0.1-0.4 mL/min). We call this method «countercurrent electroconcentration»

Relation between oil–water flow and extraction performance in liquid–liquid countercurrent centrifugal extractors with Taylor vortices

Abstract: A countercurrent centrifugal extractor with an inner rotor and a stationary outer wall has been developed in which aqueous and organic phases flow countercurrently between two walls. The formation of stable Taylor vortices in the gap makes multistage extraction possible. Understanding the relation between flow state and percent extraction is important for achieving a greater number of theoretical stages in a single extractor. Hence, oil–water countercurrent flow is measured by ultrasonic velocity profiling, without disturbing the flow, under different feed rates of solutions and rotating speeds of the inner rotor. In continuous extraction tests, Zn2+ in nitric acid and di-(2-ethylhexyl)-phosphoric acid diluted by n-dodecane are used. Measurement results are verified by numerical simulation. Finally, a correlation chart of flow patterns and operating conditions is prepared.

Effects of mass transfer on the hydrodynamic behavior of a Karr reciprocating plate column

Abstract: A 5 cm internal diameter Karr reciprocating plate column has been operated in countercurrent liquid−liquid flow in the absence of mass transfer and with mass transfer of i-propanol from the dispersed phase (Isopar M) to the continuous phase (water). The effect of mass transfer is to increase the drop diameter, while the holdup is reduced and axial dispersion is increased. Although an unstable density gradient was created by the mass-transfer process, earlier models developed under non-mass-transfer conditions, based on Kolmogoroff's isotropic turbulence theory, were not applicable in describing the enhancement in axial mixing. It was concluded that the density gradient effect was masked by the effect of the larger drops which were formed because of mass-transfer-induced coalescence. Mass-transfer coefficients for the dispersed phase were found to show the same trends as the Handlos and Baron oscillating drop model.

Method for cooling normally gaseous material

Abstract: Normally gaseous feed materials, having a pressure significantly above ambient pressure, are cooled by passing the gaseous feed through an indirect heat exchange means, such as a plate-fin heat exchanger, passing a normally gaseous refrigerant, having a pressure substantially above ambient pressure, through the heat exchange means as a first stream in a concurrent direction with the feed stream, reducing the pressure of at least one second stream of refrigerant, preferably a plurality of second streams, as it exits the heat exchange means and passing the second stream of refrigerant, which has thus been reduced in pressure, through the heat exchange means in a countercurrent direction to the feed stream. This method can be employed for each cooling cycle of a method for cooling a natural gas stream to remove components therefrom and/or liquify the same.