A hybrid refrigeration process applied in the field of natural gas cryogenic liquefaction

Abstract

The invention discloses a hybrid refrigeration process applied to a natural gas copious cooling liquidation field. Equipment of the process comprises a throttling valve, a precooling heat exchanger, an upper main cooling heat exchanger, a heavy hydrocarbon knockout drum, a lower main cooling heat exchanger, a gas-liquid separator, a refrigerant gas-liquid separation tank and a supercooling heat exchanger. The precooling heat exchanger is connected with the upper main cooling heat exchanger through a pipeline. The upper main cooling heat exchanger is connected with the heavy hydrocarbon knockout drum and the lower main cooling heat exchanger through pipelines. The heavy hydrocarbon knockout drum is connected with the lower main cooling heat exchanger through a pipeline. The lower main cooling heat exchanger is connected with the gas-liquid separator and the refrigerant gas-liquid separation tank through pipelines. The gas-liquid separator is connected with the supercooling heat exchanger through a pipeline. The hybrid refrigeration process has the beneficial effects that the structure is reasonable, the process is simple, energy consumption is low, equipment investment is low, and the refrigeration effect is good; and a hybrid refrigerant is cyclically utilized, multiple cooling links are scientifically combined and sequentially carried out, and the requirements in the practical production process are well met.

Description

[0001] Technical field: [0002] The invention relates to a refrigeration process, in particular to a mixed refrigeration process applied in the field of natural gas cryogenic liquefaction. [0003] Background technique: [0004] Natural gas is a high-quality and clean fossil energy. After liquefied, the volume of natural gas is only 1 / 625 of the original volume, so it is convenient for storage and transportation. It plays an irreplaceable role in the development and utilization of offshore natural gas and the introduction of overseas natural gas. [0005] At present, the main natural gas liquefaction methods include cascade refrigeration cycle process, mixed refrigeration cycle process and expansion refrigeration cycle process. The cascade refrigeration cycle is a three-stage refrigeration with refrigerants such as propane (or propylene), ethane (or ethylene), methane (or nitrogen) (evaporation temperatures are -38°C, -85°C, -160°C, respectively); Make natural gas exchange h...

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Problems solved by technology

[0006] Among them, the cascade refrigeration cycle process requires three large-scale cycle compressors and a considerable number of cold exchange equipment, which has a long process, many equipment, and complicated control; the mixed refrigeration cycle process needs to make the entire liquefaction process (from normal temperature to -162°C) It is difficult to completely match the required cooling capacity with the cooling capacity provided by the refrigerant. At best, it can only be partially or partially close to the cooling curve; while the expansion refrigeration cycle process often has complex processes, high energy consumption, high cost, and difficult operation. Waiting for deficiencies

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