BOG re-liquefaction process and re-liquefaction recovery system thereof

Abstract

The invention provides a BOG re-liquefaction process capable of reducing energy consumption and reducing cost and a re-liquefaction recovery system thereof. The BOG re-liquefaction process comprises the steps of 1 conducting pressure reduction on BOG from an LNG storage tank and then reheating the BOG to be at normal temperature through a heat exchanger, 2 performing supercharging through a compressor, 3 cooling the BOG to be at normal temperature and then cooling the BOG to be at the temperature ranging from -150 DEG C to -130 DEG C through the heat exchanger, 4 conducting throttling and pressure reduction to enable the liquid-state BOG to be at normal pressure, performing gas-liquid separation, returning obtained gas to the heat exchanger and then feeding the gas into the compressor, wherein a part of obtained LNG is returned to the heat exchanger and then is fed into the compressor, and the other part of obtained LNG is fed into the LNG storage tank. The BOG re-liquefaction recovery system comprises the LNG storage tank, a first throttling device, the heat exchanger, the compressor, a cooler, a second throttling device and a gas-liquid separator. By the adoption of the BOG re-liquefaction process and the BOG re-liquefaction recovery system, the energy consumption can be effectively reduced, device input can be reduced, and cost can be reduced.

Description

Technical field [0001] The invention relates to the technical field of LNG (liquefied natural gas) storage and transportation, in particular to a BOG reliquefaction process and a reliquefaction recovery system. Background technique [0002] It is well known that at present, LNG refueling stations and LNG transfer stations produce a large amount of BOG (naturally evaporated natural gas) gas, which cannot be recovered, resulting in a large amount of natural gas venting and waste. In response to this situation, the BOG reliquefaction process and its device appeared. For example, Chinese Patent Publication No. CN 103343881 A, the patent name is a process and device for recovering BOG; the application discloses a process and device for recovering BOG; the nitrogen from a nitrogen storage tank is compressed to obtain high-pressure nitrogen, Enter the BOG recovery device; in the BOG recovery device, the nitrogen is water-cooled, and then heat exchanges to obtain low-temperature and hig...

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Problems solved by technology

[0003] However, the above process of recovering BOG uses nitrogen to refrigerate BOG. ​​In the process of refrigerating nitrogen, the first choice is to compress the nitrogen and then expand and refrigerate, which requires high energy consumption; at the same time, a nitrogen compressor combination and nitrogen expansion are required. The unit refrigerates nitrogen, and there are a lot of equipment, and the structure of the nitrogen expansion unit is complex; therefore, the above-mentioned process and device for recovering BOG require high energy consumption in the process of recovering BOG, require more equipment, and have higher production costs

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