An energy-saving treatment system for evaporated gas in lng receiving station

Abstract

The invention relates to an energy-saving processing system for vapor of an LNG receiving station. A high pressure LNG transmission branch is separated from a high pressure LNG outer transmission line of an existing natural gas transmission system of the LNG receiving station; the output end of the high pressure LNG transmission branch is connected with the input end of a gas-gas ejector mixer; the output end of the gas-gas ejector mixer is connected with the input end of a short distance direct sending pipe of a natural gas user; the gas-gas ejector mixer is also provided with a low pressure suction inlet; the low pressure suction inlet is connected with the output end of a vapor-discharging total pipe of an LNG storage tank; and the vapor-discharging total pipe is provided with a vapor flow control valve that can be adjusted according to pressure conditions of the LNG storage tank. Low pressure boil-off gas discharged by cooling the LNG storage tank is absorbed by using the pressure energy of the output high temperature LNG; full mix and energy exchange between the high pressure LNG and the low pressure boil-off gas are completed in the gas-gas ejector mixer; the mixed gas is output to meet requirements of users of medium-high pressure natural gas. The energy-saving processing system is suitable for vapor treatment of large and medium LNG receiving stations with different gas state outer transportation pressure requirements.

Description

technical field [0001] The invention relates to an LNG receiving station boil-off gas processing system, in particular to an LNG receiving station boil-off gas energy-saving processing system capable of absorbing low-pressure boil-off gas by using the self-pressure of the high-pressure natural gas exported from abroad. Background technique [0002] LNG receiving stations generally undertake the functions of receiving, storing and gasifying LNG for export. Since LNG (Liquefied Natural Gas, liquefied natural gas) is a cryogenic fluid, although LNG equipment has good insulation measures, it will inevitably produce a certain amount of BOG (Boiled Off Gas, boil-off gas) during production and operation. With BOG As the quantity continues to increase, the temperature and pressure in the LNG storage system will gradually increase. If the internal pressure of the LNG storage tank is higher than the safety relief pressure set by the system, the safety valve on the top of the storage ...

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Problems solved by technology

This leads to the need to install equipment such as medium-pressure compressors, high-pressure compressors, recondensers, and pressure regulating valves, resulting in many problems such as high investment, high energy consumption, cumbersome operations, and complicated processes, and there are still applications that require working conditions. limit

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