Low-temperature BOG (Boil off Gas) gas cold energy recovering device and process

Abstract

The invention discloses a low-temperature BOG (Boil off Gas) gas cold energy recovering device. A low-temperature BOG gas inlet pipe (1) is sequentially connected with a heater (2), a heat exchanger (3) and a buffering tank (4) in one path, and is connected with a pipeline through a branched pipe A (7) in another path, wherein the pipeline connects the heater (2) with the heat exchanger (3); a buffering tank (4) is connected with a compressor (5); and the compressor (5) is sequentially connected with a booster BOG gas flowing channel and a booster BOG gas outlet pipe (6) of the heat exchanger (3) in one path, and is connected with the booster BOG gas outlet pipe (6) through a branched pipe B (8) in another path. The invention also discloses a cold energy recovering process. The cold energy recovering process has the beneficial effects that the gas obtained by cooling and compressing under the cold energy of the low-temperature BOG gas and the regeneration/cold blowing air before entering a heavy hydrocarbon separator are utilized, the cold and heat process mediums are fully utilized for exchanging heat, so that the energy is saved, and the consumption is reduced; and the pipeline is reasonable and simple in design; the applicable scope is wide; and the convenience is provided for conditioning.

Description

technical field [0001] The invention relates to the technical field of complete sets of natural gas liquefaction devices, in particular to a low-temperature BOG gas cooling recovery device and a process. Background technique [0002] LNG is the abbreviation of liquefied natural gas. It is obtained by liquefying natural gas at low temperature after purification processes such as deacidification, dehydration, desulfurization, and deheavy hydrocarbons. The main component is methane. The use of LNG can greatly reduce the transportation and storage costs of natural gas. [0003] Existing natural gas liquefaction complete sets and LNG storage devices usually use air-temperature heaters to reheat low-temperature BOG gas, and then the reheated BOG gas goes to the compressor, which pressurizes the BOG gas. The temperature of the low-temperature BOG gas before entering the compressor is affected by the low temperature of the environment in autumn and winter, resulting in insufficient...

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Problems solved by technology

[0004] In addition, due to the high temperature of the medium in the existing method for removing heavy hydrocarbons at room temperature, the recovery rate of heavy hydrocarbons in the heavy hydrocarbon separator is low, especially in summer. The regeneration / cold gas blowing temperature of hydrocarbon units is usually above 30°C, and the recovery rate of heavy hydrocarbons is low

[0005] In the existing process, the low-temperature BOG gas is heated by an air-to-air heat exchanger, and the cooling capacity is completely lost, and the cooling capacity of the low-temperature BOG gas is not recycled; at the same time, the BOG gas needs to be further cooled after being pressurized by the compressor, and the degassing The regeneration\cold gas blowing of heavy hydrocarbon units also requires further cooling

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