BOG recovery system for LNG (Liquefied Natural Gas) gas station

Abstract

The invention relates to the field of liquefying equipment, and provides a BOG recovery system for an LNG (Liquefied Natural Gas) gas station. The BOG reclaiming system comprises a BOG introduction pipeline, a compressor, a cooler, an ejector and an LNG discharging pipeline, wherein the BOG introduction pipeline, the compressor, the cooler, the ejector and the LNG discharging pipeline are sequentially communicated with one another. The BOG in an LNG storage tank enters the compressor through the BOG introduction pipeline and is pressurized to about 20MPa, the pressurized BOG is cooled by the cooler and enters the ejector to perform ejection liquefaction, and finally, the obtained LNG is introduced into a storage device as products. Through the adoption of the BOG recovery system disclosed by the invention, the BOG generated in the LNG storage tank can be re-liquefied, and the re-liquefied BOG can be introduced into the LNG storage tank or other containers so as to be sufficiently utilized, and the air pollution and the waste of energy sources can be avoided. The BOG recovery system is suitable for LNG gas stations.

Description

technical field [0001] The invention relates to the field of liquefaction equipment, in particular to a BOG recovery system of an LNG filling station. Background technique [0002] Because the LNG (liquefied petroleum gas) storage tank is invaded by the heat of the external environment, or part of the mechanical energy is converted into heat energy when the submerged pump in the LNG storage tank is running, the LNG in the tank will be vaporized to produce flash gas, which is BOG gas. LNG filling stations will produce a large amount of BOG. ​​If these BOG are directly discharged into the atmosphere, it will not only waste precious resources, but also pollute the atmospheric environment and pose a safety hazard. At present, the traditional LNG liquefaction has the following two methods: one is to compress the gas first, and then pass it into the expander. The gas does work in the expander and releases energy to do mechanical work, so that the temperature is lowered and liquefi...

AI Technical Summary

Problems solved by technology

LNG filling stations will produce a large amount of BOG. ​​If these BOG are directly discharged into the atmosphere, it will not only waste precious resources, but also pollute the atmospheric environment and pose a safety hazard.

At present, the traditional LNG liquefaction has the following two methods: one is to compress the gas first, and then pass it into the expander. The gas does work in the expander and releases energy to do mechanical work, so that the temperature is lowered and liquefied. The rated flow rate of the existing expander is too high. However, the flow rate of the expander required by the LNG filling station recovery equipment is too small, so it is not suitable for the LNG filling station; the second is to use MR cycle refrigeration, that is, to use the mixed refrigerant to exchange heat with BOG, but the normal seepage of the refrigerant Leakage will cause difficulty in refrigerant filling and proportioning, making it difficult to achieve stable operation of the device

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