turboexpander
Cryogenic chilling in the PETROGAS Model TE System utilizes a TURBOEXPANDER which replaces the Joule-Thompson expansion valve in a conventional refrigeration system. The expansion valve is adiabatic, while a turbine, taking work out of the expansion makes it isentropic.
Isentropic expansion allows for a lower temperature of the expanded refrigerant at the same pressure reduction. The more efficient turboexpansion cycle allows the use of aliphatic hydrocarbons, such as ethane, as a refrigerant.
In the Model TE series, a gas turbine with a shaft connecting it to a single stage gas compressor is known as a TURBOEXPANDER, in which a high pressure refrigerant gas flows into the gas turbine, expanding across the turbine blades, rotating a shaft and cooling through the isentropic gas expansion to a cryogenic temperature of less than -100°F. The existing low pressure, cryogenic temperature gas is used to cool the air/vapor mixture to a temperature of -100°F, condensing the contained vapors.
The transfer of heat from the air/vapor mixture, raises the temperature of the refrigerant gas, which then enters the compressor side of the TURBOEXPANDER, partially recompressing the refrigerant gas to the inlet design pressure of the gas turbine, completing the cycle. The TURBOEXPANDER is able to cool a gas to cryogenic temperatures using 30%-60% less compressor horsepower than is required for conventional cascade type refrigeration systems.
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