A pump relay mode output system and method for LNG peak regulation

Abstract

The invention discloses a pump relay mode output system and method for LNG peak regulation, which includes an LNG storage tank and a gasification device, a main line is arranged between the LNG storage tank and the gasification device, and a low-pressure pump, a high-pressure pump and a return flow pump device, the low-pressure pump is set inside the LNG storage tank, and the high-pressure pump is set outside the LNG storage tank; one end of the main line is connected to the low-pressure pump, and the other end of the main line is connected to the gasification device. The high-pressure pump is arranged on the main line and between the low-pressure pump and the gasification device; one end of the return device is communicated with the main line, and the other end of the return device is connected with the LNG storage tank. The invention can realize the output of the material in the LNG storage tank to the gasification device, regulate the LNG flow according to the downstream demand to match the user's demand, meet the on-site demand of frequent switching on and off, and effectively improve the working efficiency of the peak-shaving station. Save energy and reduce consumption, reduce operating costs.

Description

technical field [0001] The invention belongs to the technical field of liquefied natural gas, and in particular relates to a pump relay mode output system and method for LNG peak regulation. Background technique [0002] Liquefied natural gas (LNG) is one of the important sources of energy in my country's energy supply. As the main source of urban gas in my country, the consumption of natural gas is increasing, and frequent gas shortages have seriously affected residents' lives and industries. [0003] my country's LNG supply is usually carried out at LNG peak-shaving stations. According to the needs of downstream users, the materials stored in LNG storage tanks are gasified and then transported to industrial and civil users. At the same time, a small part of LNG needs to be transported to LNG The direct liquid transport by tank truck is affected by the peak shaving and seasonal fluctuations of downstream users. Before the liquefied natural gas in the LNG storage tank is gasi...

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Problems solved by technology

[0004] At present, the means to realize the output of the material in the LNG storage tank to the gasification device is usually the high-pressure method in the tank, that is, the high-pressure submersible pump is installed in the LNG storage tank, and the LNG stored in the LNG storage tank is directly pressurized to the required pressure. It is then input to the gasification device, but it has the following problems: 1. The high-pressure submersible pump can only realize the high-pressure gasification function, and cannot meet the direct liquid transportation to the LNG tanker; 2. The needs of downstream users are constantly changing, and LNG The operation of the peak shaving station is often in a state of frequent start-up and shutdown, which requires frequent pre-cooling of the pipeline after reheating. The high-flow low-temperature fluid output by the high-pressure submersible pump will cause a large cold impact on the pipeline, and the pipeline is subject to local cold stress. Excessive impact shrinkage will cause pipeline accidents; 3. The power of the high-pressure submersible pump is high, and it is necessary to install a matching high-pressure pump well and a high-voltage incoming motor in the LNG storage tank, and the demand for power distribution supporting input and professional and technical personnel is high

[0005] At present, it is difficult to achieve the expected goal by setting the buffer device to solve the LNG flow matching. As a low-temperature fluid, LNG will inevitably produce a certain amount of BOG (boil-off gas) during production and operation, which is different from water phase, so It is difficult to solve the problem with the solution similar to the water buffer device. At the same time, as the BOG content in the LNG storage tank increases, the temperature and pressure of the LNG storage tank increase. If the BOG in the storage tank is not treated in time, the Accumulated BOG can easily cause safety accidents

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