A storage tank recovery bog non-emission LNG gas filling device and method

Abstract

The invention relates to a storage tank recovery BOG discharge-free LNG gas-filling device and method. The device comprises an LNG storage tank (2), a gas-filling gun (34), a gas-returning gun (36), a high pressure gas-filling tank (3) and a compression device (50), wherein the LNG storage tank is provided with a gas phase connector (2a) and a liquid phase connector (2b), and the high pressure gas-filling tank is provided with a gas phase connector (3a) and a liquid phase connector (3b), respectively; the gas phase connector of the LNG storage tank is connected to the gas phase connector of the high pressure gas-filling tank through the compression device, the gas-returning gun is connected to the gas phase connector of the high pressure gas-filling tank through the compression device, and the gas-returning gun is connected to the liquid phase connector and the gas phase connector of the LNG storage tank through a pipeline. The device and method provided by the invention have the beneficial effects that in a gas-filling process, BOG in an LNG cylinder is mixed with low-temperature liquid LNG in the LNG storage tank to be re-liquefied, so that BOG discharge is avoided; BOG gas is compressed by a bidirectional low-temperature compression device during gas-filling, tank-pouring and unloading, and no BOG discharge is available in the whole course; liquefied recovery of BOG is realized, so that the device and method have remarkable environmental-friendly and energy-saving effects.

Description

technical field [0001] The invention belongs to the field of gas filling of liquefied natural gas, and in particular relates to a storage tank recovery BOG emission-free LNG gas filling device and method. Background technique [0002] At present, there are two types of LNG refueling devices. One is to use LNG pumps to extract LNG (liquefied natural gas) liquid from LNG storage tanks, and to refill LNG cylinders after the pump is pressurized; the other is to use boosters to increase LNG storage tank pressure, use the pressure difference between the LNG storage tank and the LNG cylinder to refuel. Both types of filling devices have only one LNG storage tank. [0003] The former method has a low-pressure LNG storage tank, and a cryogenic submersible pump and a pump pool are installed outside the storage tank. The LNG is pressurized by the cryogenic pump installed in the pump pool. However, the LNG liquid needs to flow into the pump before adding gas. Pool, which is to pre-coo...

AI Technical Summary

Problems solved by technology

[0003] The former method has a low-pressure LNG storage tank, and a cryogenic submersible pump and a pump pool are installed outside the storage tank. The LNG is pressurized by the cryogenic pump installed in the pump pool. However, the LNG liquid needs to flow into the pump before adding gas. Pool, which is to pre-cool the pump pool and enter the liquid, each pre-cooling will produce BOG (liquefied natural gas volatile gas), resulting in more BOG, and because of the low-pressure storage tank used, the pre-cooled BOG returns to the LNG storage tank Finally, the BOG gas is discharged in order to avoid the pressure increase of the storage tank

The discharge of BOG will cause safety hazards, and the overall system of this method is complicated and the cost is high

[0004] The latter method is to use a supercharger to pressurize the LNG storage tank. This method is often used in LNG refueling vehicles. Since a higher pressure is required to refill the tank, the stainless steel inner tank is designed to withstand higher pressure. Thicker materials are required, resulting in a bulky device; this method is common in small pumpless refueling vehicles, and it is uneconomical to apply to large refueling vehicles, and it cannot meet the needs of road transportation. The vehicle replenishes liquid to it. Due to the high pressure, there will be more discharge when the liquid is replenished, so it cannot be put into production and use in large quantities.

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