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Dual Mixed Refrigerant Cycle for Natural Gas Liquefaction

IP.com Disclosure Number: IPCOM000241299D
Publication Date: 2015-Apr-14
Document File: 3 page(s) / 202K

Publishing Venue

The IP.com Prior Art Database

Abstract

Dual Mixed Refrigerant (DMR) cycle where a natural gas feed is first precooled by precooling mixed refrigerant in a precooling heat exchanger. Precooled feed is then liquefied and subcooled in the main heat exchanger before being sent to storage.

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Dual Mixed Refrigerant Cycle for Natural Gas Liquefaction

Figure 1 shows a schematic of a Dual Mixed Refrigerant (DMR) cycle where a natural gas feed is first precooled by precooling mixed refrigerant in a precooling heat exchanger.  Precooled feed is then liquefied and subcooled in the main heat exchanger before being sent to storage. 

Liquefaction and subcooling refrigeration is provided by mixed refrigerant containing an optimal composition of Nitrogen, Methane, Ethane or Ethylene, Propane, iso-Butane, n-Butane, iso-Pentane and other hydrocarbons.  The MR is compressed to high pressure and is precooled by precooling mixed refrigerant in a precooling heat exchanger.  The precooled two phase MR stream is phase separated producing a liquid mixed refrigerant and vapor mixed refrigerant.  The liquid mixed refrigerant is subcooled in the main heat exchanger.  The liquid mixed refrigerant exits the main heat exchanger and is reduced in pressure across a Joule Thomson valve or any other suitable device and is returned to the main heat exchanger to provide refrigeration.  The vapor mixed refrigerant is liquefied and subcooled in the main heat exchanger.  The vapor mixed refrigerant exits the cold end of the main heat exchanger and is reduced in pressure across a Joule Thomson valve or any other suitable device and is returned to the main heat exchanger to provide refrigeration.  The vapor mixed refrigerant and liquid mixed refrigerant combine inside the main heat exchanger to provide refrigeration to the natural gas feed, vapor mixed refrigerant and liquid mixed refrigerant.

Precooling refrigeration is provided by mixed refrigerant containing an optimal composition of components such as Nitrogen, Methane, Ethane or Ethylene, Propane, iso-Butane, n-Butane, iso-Pentane and other hydrocarbons.  The precooling mixed refrigerant is compressed and cooled in an intercooler / partial condenser to produce a liquid and vapor.  The vapor is further compressed and is combined with high pressure liquid that was pumped from the inter-stage suction drum.  The combined liquid and vapor MR streams are partially condensed in the precooling compressor aftercooler / condenser.  The liquid may then be sent to a dedicated MR circuit in the precooling heat exchanger, while the vapor may be sent to a separate MR circuit in the precooling heat exchang...