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Natural Gas Liquefaction Method

IP.com Disclosure Number: IPCOM000245219D
Publication Date: 2016-Feb-18
Document File: 2 page(s) / 109K

Publishing Venue

The IP.com Prior Art Database

Abstract

This disclosure describes methods for liquefying a natural gas stream using at least one gas phase refrigerant. The refrigerant may be nitrogen, methane, a mixture thereof, or any other suitable refrigerant.

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Natural Gas Liquefaction Method

This disclosure describes methods for liquefying a natural gas stream using at least one gas phase refrigerant.  The refrigerant may be nitrogen, methane, or any other suitable refrigerant. Any type of heat exchangers may be utilized such as plate and fin, coil wound, shell and tube, etc.

Figure 1

Figure 1 shows a closed-loop refrigeration with at least one stage of nitrogen expansion to cool and liquefy the natural gas feed stream. The low pressure nitrogen stream 1 is first compressed and cooled to make a high pressure nitrogen stream 2. The compressed nitrogen stream 2 may be further cooled in heat exchanger 3 before expanding in expander 4.  The low pressure, cold nitrogen refrigerant from expander 4 enters the main exchanger 5 and 3 to provide refrigeration to cool and liquefy the natural gas feed stream 6. 

The natural gas feed stream is liquefied after heat exchangers 3 and 5, with a temperature around -100 to -130oC.  It goes through multiple flash steps in a series of flash drums 7 and 8 (any number of stages are possible) and multiple heat exchange steps with the flash gas streams it produces, becoming further cooled, to a temperature below -140oC.

The cold and low pressure flash gas streams are recycled back to the warm end of the heat exchanger by: (a) warming up against the LNG streams and high pressure recycled flash gas, (b) compressing to high pressure, and (c) cooled against the cold and low pressure flash gas recycle stre...