Pressure Exchanger

A pressure exchanger transfers pressure energy from a high pressure fluid stream to a low pressure fluid stream. Many industrial processes operate at elevated pressures and have high pressure waste streams. One way of providing a high pressure fluid to such a process is to transfer the waste pressure to a low pressure stream using a pressure exchanger.

One particularly efficient type of pressure exchanger is a rotary pressure exchanger. This device uses a cylindrical rotor with longitudinal ducts parallel to its rotational axis. The rotor spins inside a sleeve between two end covers. Pressure energy is transferred directly from the high pressure stream to the low pressure stream in the ducts of the rotor. Some fluid that remains in the ducts serves as a barrier that inhibits mixing between the streams. This rotational action is similar to that of an old fashioned machine gun firing high pressure bullets and it is continuously refilled with new fluid cartridges. The ducts of the rotor charge and discharge as the pressure transfer process repeats itself.

The performance of a pressure exchanger is measured by the efficiency of the energy transfer process and by the degree of mixing between the streams. The energy of the streams is the product of their flow rates and pressures. Efficiency is a function of the pressure differentials and the volumetric losses (leakage) through the device computed with the following equation:

where Q is flow, P is pressure, L is leakage flow, HDP is high pressure differential, LDP is low pressure differential, the subscript B refers to the low pressure feed to the device and the subscript G refers to the high pressure feed to the device. Mixing is a function of the concentrations of the species in the inlet streams and the ratio of flow rates to the device.

Read more about Pressure Exchanger:  Reverse Osmosis With Pressure Exchangers, Energy Recovery and Pressure Exchange Systems

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... The compressor pumps the refrigerant gas up to a high pressure and temperature ... From there it enters a heat exchanger (sometimes called a "condensing coil" or condenser) where it loses energy (heat) to the outside ... The liquid refrigerant is returned indoors to another heat exchanger ("evaporating coil" or evaporator) ...
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... which made potable water from seawater by forcing it under high pressure through a tight membrane thus filtering out salts and impurities ... as a concentrated brine solution in a continuous stream, which contains a large amount of high-pressure energy. 6.0 kWh per cubic meter of potable water produced, due to low membrane performance, pressure drop limitations and the absence of energy recovery devices ...

Famous quotes containing the words exchanger and/or pressure:

    I want to know whether you are a person devoted to creating or to exchanging in some respect or other: as a creator you belong to the free, as an exchanger you are their slave and instrument.
    Friedrich Nietzsche (1844–1900)

    Destiny is an absolutely definite and inexorable ruler. Physical ability and moral determination count for nothing. It is impossible to perform the simplest act when the gods say “no.” I have no idea how they bring pressure to bear on such occasions; I only know that it is irresistible.
    Aleister Crowley (1875–1947)