BOG (boil off gas) recovery processing method and system for LNG (liquid natural gas) receiving terminal

Abstract

The invention relates to a BOG (boil off gas) recovery processing method and system for an LNG (liquid natural gas) receiving terminal, and the BOG recovery processing method comprises the following steps: 1) setting a BOG recovery processing system under the working condition of no output operation of the LNG receiving terminal; 2) feeding BOG produced in an LNG full containment storage tank to the lower end of a BOG re-condenser after BOG is pressurized by a BOG compressor; 3) conveying overcooled LNG from the LNG full containment storage tank to the upper end of the BOG re-condenser by virtue of a pump in the LNG tank, and coming into contact with the BOG at the lower end of the BOG re-condenser to perform heat transfer so as to condense the BOG into LNG; 4) feeding LNG from the BOG re-condenser into an LNG main-sub tank, and then feeding the LNG from the LNG main-sub tank into an output loading system; and 5) feeding the BOG produced in the BOG re-condenser, the LNG main-sub tank and the output loading system into the BOG compressor for pressurizing together with the BOG in the LNG full containment storage tank through throttle control, feeding the pressurized BOG to the lower end of the BOG re-condenser, and going back to the step 3). The invention provides a BOG recovery processing method and system, which are capable of ensuring effective recovery utilization of BOG and can be widely applied to recovery utilization of BOG in the LNG receiving terminal.

Description

technical field [0001] The invention relates to a method and system for comprehensive processing of BOG at an LNG (liquefied natural gas) receiving terminal, in particular to a method and system for recovering and processing BOG at an LNG receiving terminal under the operating condition of no external transportation. Background technique [0002] In recent years, global LNG production and trade have become increasingly active. As a clean and efficient strategic energy source, LNG is becoming a new hotspot in the world's oil and gas industry. At present, my country is vigorously building LNG receiving terminals along the coast, which is conducive to stabilizing energy supply, ensuring energy security, diversifying the supply structure, and protecting the environment. [0003] The daily evaporation rate of LNG in cryogenic storage tanks and cryogenic tankers is about 0.3%. This part of evaporated gas (lower temperature) is referred to as BOG (flash steam, Boil Off Gas). The LN...

AI Technical Summary

Problems solved by technology

[0004] At present, the downstream market of many LNG receiving terminals has not been opened, the downstream demand is insufficient, and there is a situation that it cannot be exported. The existing LNG receiving terminal BOG processing technology mainly includes direct compression process and reliquefaction process, both of which have their own shortcomings. The power consumption of direct compression process The LNG cooling capacity cannot be recovered during the external transportation at the receiving station; the reliquefaction process is difficult to operate when the load of the natural gas transmission network fluctuates, and when there is no external transportation at the receiving station, BOG can only be disposed of by venting or torching, which wastes Resources are not conducive to environmental protection

At present, the downstream market of many LNG receiving terminals has not been opened, the downstream demand is insufficient, and there is a situation that it cannot be exported. It is necessary to seek a new BOG treatment process to save investment and reduce production costs.

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