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Power recovery cycle for Nitrogen from an Elevated Pressure Air Separation plant or other another pressurised stream

IP.com Disclosure Number: IPCOM000032043D
Publication Date: 2004-Oct-20
Document File: 2 page(s) / 25K

Publishing Venue

The IP.com Prior Art Database

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Power recovery cycle for Nitrogen from an Elevated Pressure Air Separation plant or other another pressurised stream

A pressurised gas stream is humidified, expanded with the performance of external work, cooled to recover most of the water and then either vented or used as feed to another process.

In example 1, a cool, pressurised stream 100 (for example waste nitrogen from an elevated pressure air separation plant) is humidified in a saturation tower 10 with hot water stream 150 to produce stream 105.  A cooled water stream 155 is withdrawn from the bottom of the tower for introduction to direct contact cooler 20.  Stream 105 is expanded in expander 15 to generate power and the expanded stream 110 is cooled in a direct contact cooler 20 to recover some of the water.  The cooled stream 115 is vented to atmosphere.  A warmed water stream 160 from the bottom of the direct contact cooler is pumped in pump 25 through a heater 30 to form the warm water stream 150 that is fed to the top of the saturation tower 10.  A makeup water stream 170 is added at some point in the system, for example at the top of cooler 20 to balance the water loss in stream 115.  An alternative to the direct contact cooler 20 is an indirect contact cooler to condense water from stream 155.  Addition of moisture to the pressurised stream 100 boosts the power recovery compared to heating the gas to the same temperature without humidification prior to expansion.  It allows more power to be recovered...