Natural gas liquefaction system based on propane and iso-butane mixed pre-cooling

Abstract

The invention discloses a natural gas liquefaction system based on propane and iso-butane mixed pre-cooling. A mixed refrigerant compression skid and a mixed precoolant compression skid are adopted tobe matched with a three-stage heat exchanger; by using the mixed refrigerant compression skid, natural gas to be liquefied is pre-liquefied and separated so that the separating efficiency of the natural gas to be liquefied is enhanced and the separating speed of the natural gas to be liquefied is increased; and then through precoolant cooling circulation of the mixed precoolant compression skid,a first heat exchanger, a second heat exchanger, a third heat exchanger and the mixed refrigerant compression skid, gas phase natural gas which is separated in the first stage is liquefied; by using the mixed precoolant compression skid to perform pre-cooling, the power loss of the mixed precoolant compression skid is reduced; through first-stage separation of liquid phase natural gas and by usinga mixed precoolant and a mixed refrigerant to exchange energy in the first heat exchanger, the second heat exchanger and the third heat exchanger, the structure is simple, the energy loss of the mixed refrigerant is reduced, the liquefaction efficiency is enhanced, and meanwhile, the liquefaction cost is reduced.

Description

technical field [0001] The invention belongs to a natural gas liquefaction process, in particular to a natural gas liquefaction system based on propane and isobutane mixed precooling. Background technique [0002] With the global demand for low-carbon emission reduction, natural gas, as a clean fossil fuel, is used in more and more fields. For many small natural gas fields, associated gas in oil fields, and coalbed methane, these natural gas resources are often scattered in remote areas. Although the reserves of these natural gas resources are small, the recovery of these scattered natural gas still has certain economic value. Small skid-mounted liquefaction processes liquefy natural gas into liquefied natural gas (LNG), which is then transported to large natural gas distribution centers using trucks. Since the skid-mounted liquefaction equipment is assembled from multiple working components, the liquefaction equipment can be transported to other gas fields by truck after ...

AI Technical Summary

Problems solved by technology

However, the liquefaction refrigeration cost of the small skid-mounted liquefaction process accounts for 42% of the total cost of the LNG project. The existing liquefaction process has high cost, high energy consumption, and cumbersome process. Cost and return on investment are closely related, and there is an urgent need to improve the existing liquefaction process to further reduce the cost of liquefaction

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