An optimized L-CNG filling station tank pressurization system and pressurization method

Abstract

The present invention relates to the field of LNG technology, and in particular to an optimized L-CNG filling station tank boosting system and boosting method, the boosting system comprising a plunger pump, a storage tank and a supercharger connected by pipelines, the liquid inlet of the supercharger being connected to the first liquid outlet of the storage tank via pipeline one, and the gas outlet of the supercharger being connected to the gas phase port and the first liquid inlet of the storage tank via pipeline two, respectively. Compared with the prior art, the optimized L-CNG filling station tank boosting system and boosting method provided by the present invention fully utilizes existing interfaces and equipment, optimizes and adjusts the process flow, and realizes changes in the process flow only through pipeline modification, and can simultaneously realize the normal operation of boosting and plunger pump operation, with low modification cost, which not only does not reduce the system operation efficiency, but also makes the tank boosting process more stable and uniform, thereby improving the tank boosting efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of LNG, and in particular to an optimized L-CNG filling station tank pressurization system and a pressurization method. Background Art

[0002] In the existing LNG filling station refueling process, the LNG in the tank enters the tank booster through the pipeline from the tank booster liquid phase port, absorbs the heat of the air in the tank booster and becomes gaseous, and then enters the upper gas phase space of the tank from the gas phase port on the top of the tank, thus realizing the pressurization process of the tank; the LNG at the bottom of the tank enters the plunger pump from the liquid outlet, and under the pressure of the plunger pump, a high-pressure liquid is formed and flows into the next process equipment from the plunger pump outlet pipe. Before the LNG enters the plunger pump and is pressurized, part of the LNG absorbs heat and vaporizes to form BOG, which flows back to the gas phase port on the top of the tank through the return pipe, thus realizing the recycling of BOG. The plunger pump return pipe of the L-CNG filling station and the tank pressurized gas phase pipeline are combined into one pipeline and then connected to the gas phase port on the top of the tank. When the gas filling is at its peak, the tank pressurization process and the plunger pump return process run simultaneously, which will form an air blockage at the gas phase port on the top of the tank, resulting in slow pressurization and reduced operating efficiency of the plunger pump. If they do not run simultaneously, the operating efficiency and gas supply capacity of the entire system will be affected, and even insufficient supply may occur. If a gas phase pipe port is added to the tank to separate the tank pressurized gas phase port and the L-CNG plunger pump return pipe port, advance communication and confirmation between the process or operation department and the purchasing department is required, and the increase in interfaces will affect the structural design of the tank and the overall vacuum effect. Summary of the invention

[0003] In view of the deficiencies of the above-mentioned background technology, the present invention provides an optimized L-CNG filling station tank pressurization system and pressurization method.

[0004] The technical solution adopted by the present invention is as follows: an optimized L-CNG filling station tank boosting system, including a plunger pump, a tank and a booster connected by pipelines, the key being that the liquid inlet of the booster is connected to the first liquid outlet of the tank through pipeline 1, and the gas outlet of the booster is connected to the gas phase port and the first liquid inlet of the tank through pipeline 2. The effect of this solution is to provide multiple boosting gas inlets, change the flow direction of the boosting gas, and meet the requirements of the boosting process and the return gas process running simultaneously.

[0005] Preferably, the storage tank is provided with a second liquid inlet, and the first liquid inlet and the second liquid inlet are connected to the same liquid inlet pipeline. The effect of this solution is that the storage tank can be replenished with liquid through multiple liquid inlets.

[0006] Preferably, the pipeline 2 includes a first branch pipe and a second branch pipe, the first branch pipe is connected to the liquid inlet pipeline, and the second branch pipe is connected to the gas phase port of the storage tank.

[0007] Preferably, the liquid inlet of the plunger pump is connected to the second liquid outlet of the storage tank through pipeline three, and the air return port of the plunger pump is connected to the second branch pipe through pipeline four.

[0008] Preferably, the bottom of the storage tank is provided with the first liquid outlet, the second liquid outlet and the second liquid inlet, and the top of the storage tank is provided with the gas phase port and the first liquid inlet. The effect of this solution is that the flow efficiency of the liquid phase and the gas phase can be improved.

[0009] Preferably, the pipeline 1, the first branch pipe, the second branch pipe, the pipeline 3 and the pipeline 4 are respectively provided with a second emergency shut-off valve, a fifth cryogenic shut-off valve, a third cryogenic shut-off valve, a third emergency shut-off valve and a fourth cryogenic shut-off valve. The effect of this solution is to realize automatic control of the storage tank pressure.

[0010] Preferably, the storage tank is provided with an annular liquid inlet pipe, which is arranged near the top of the storage tank, the liquid inlet end of the annular liquid inlet pipe is connected to the first liquid inlet port, and a plurality of nozzles are evenly distributed on the annular liquid inlet pipe. The effect of this solution is that the liquid inlet from the top of the storage tank can be evenly distributed in the entire gas phase space of the storage tank in a shower-like structure.

[0011] Preferably, the liquid inlet pipeline is provided with a first emergency shut-off valve, a first cryogenic shut-off valve, a second cryogenic shut-off valve and a sixth cryogenic shut-off valve, the first emergency shut-off valve is located in the main pipe section of the liquid inlet pipeline, the first cryogenic shut-off valve is located in the branch pipe section between the first emergency shut-off valve and the first liquid inlet, the second cryogenic shut-off valve is located in the branch pipe section between the first emergency shut-off valve and the second liquid inlet, and the sixth cryogenic shut-off valve is located in the branch pipe section between the first cryogenic shut-off valve and the second cryogenic shut-off valve. The effect of this solution is that it can prevent the BOG generated by the boosting from returning to the storage tank from the liquid inlet at the bottom of the storage tank, which can neither achieve the purpose of boosting nor form air blockage, which is not conducive to the discharge of LNG from the bottom of the storage tank.

[0012] An optimized L-CNG filling station tank pressurization system pressurization method includes the following steps:

[0013] S1. Determine the start-up status of the plunger pump air return process;

[0014] S2. When the plunger pump air return process is started, close the third cryogenic shut-off valve V03, open the fifth cryogenic shut-off valve V07, and start the tank pressurization process;

[0015] S3. When the plunger pump air return process stops, open the fifth cryogenic shut-off valve V07 or the third cryogenic shut-off valve V03 to start the tank pressurization process.

[0016] Preferably, S2 specifically comprises: starting the plunger pump, LNG enters the plunger pump from the bottom of the storage tank through pipeline three, and forms high-pressure liquid under the pressure-boosting action of the plunger pump, and flows into the next process equipment from the liquid outlet pipe of the plunger pump. Before the LNG enters the plunger pump and is pressurized, part of the LNG absorbs heat and vaporizes to form BOG, and the BOG flows back to the gas phase port at the top of the storage tank through pipeline four, closing the third low-temperature stop valve V03 and the sixth low-temperature stop valve, and opening the fifth low-temperature stop valve V07. The LNG in the storage tank enters the storage tank booster from the bottom of the storage tank through pipeline one, and after absorbing the heat of the air in the storage tank booster to become gaseous, enters the storage tank from the first liquid inlet at the top of the storage tank through the first branch pipe to pressurize the storage tank;

[0017] S3 is specifically as follows: open the third cryogenic stop valve V03, close the fifth cryogenic stop valve V07, the LNG in the storage tank enters the storage tank supercharger from the bottom of the storage tank through pipeline 1, absorbs the heat of the air in the storage tank supercharger and becomes gaseous, then enters the storage tank from the gas phase port at the top of the storage tank through the second branch pipe, and pressurizes the storage tank; close the third cryogenic stop valve V03 and the sixth cryogenic stop valve, open the fifth cryogenic stop valve V07, the LNG in the storage tank enters the storage tank supercharger from the bottom of the storage tank through pipeline 1, absorbs the heat of the air in the storage tank supercharger and becomes gaseous, then enters the storage tank from the first liquid inlet at the top of the storage tank through the first branch pipe, and pressurizes the storage tank.

[0018] Beneficial effect: Compared with the prior art, the optimized L-CNG filling station tank pressurization system and pressurization method provided by the present invention fully utilize the existing interfaces and equipment, optimize and adjust the process flow, and realize the change of the process flow only through pipeline modification. It can realize the normal operation of the pressurization and plunger pump at the same time, and the modification cost is low. It not only does not reduce the system operation efficiency, but also can make the tank pressurization process more stable and uniform, thereby improving the tank pressurization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] Example 1

[0022] An optimized L-CNG filling station tank boosting system includes a plunger pump 1, a storage tank 2 and a supercharger 3 connected by pipelines, wherein the liquid inlet of the supercharger 3 is connected to the first liquid outlet of the storage tank 2 through a pipeline 1 4, and the gas outlet of the supercharger 3 is connected to the gas phase port and the first liquid inlet of the storage tank 2 through a pipeline 2 5.

[0023] Example 2

[0024] An optimized L-CNG filling station tank boosting system comprises a plunger pump, a storage tank 2 and a supercharger 3 connected by pipelines, wherein the bottom of the storage tank 2 is provided with a first liquid outlet, a second liquid outlet and a second liquid inlet, the top of the storage tank 2 is provided with a gas phase port and a first liquid inlet, an annular liquid inlet pipe 9 is provided in the storage tank 2, the annular liquid inlet pipe 9 is arranged close to the top of the storage tank 2, the liquid inlet end of the annular liquid inlet pipe 9 is connected with the first liquid inlet, a plurality of nozzles are evenly distributed on the annular liquid inlet pipe 9, the liquid inlet of the plunger pump is connected with the second liquid outlet through a pipeline three 7, the liquid inlet of the supercharger 3 is connected with the first liquid outlet through a pipeline one 4, the gas outlet of the supercharger 3 is respectively connected with the gas phase port and the first liquid inlet through a pipeline two 5, and the first liquid inlet and the second liquid inlet are connected with the same liquid inlet pipeline 6;

[0025] The pipeline 2 5 includes a first branch pipe 51 and a second branch pipe 52, the first branch pipe 51 is connected to the liquid inlet pipeline 6, the second branch pipe is connected to the gas phase port, and the return port of the plunger pump 1 is connected to the second branch pipe 52 through a pipeline 4 8; the pipeline 1 4, the first branch pipe 51, the second branch pipe 52, the pipeline 3 7 and the pipeline 4 8 are respectively provided with a second emergency shut-off valve PV02, a fifth low-temperature shut-off valve V07, a third low-temperature shut-off valve V03, a third emergency shut-off valve PV03 and a fourth low-temperature shut-off valve V06; the liquid inlet pipeline 6 is provided with a An emergency shut-off valve PV01, a first low-temperature shut-off valve V01, a second low-temperature shut-off valve V02 and a sixth low-temperature shut-off valve, wherein the first emergency shut-off valve PV01 is located in the main pipe section of the liquid inlet pipeline 6, the first low-temperature shut-off valve V01 is located in the branch pipe section between the first emergency shut-off valve PV01 and the first liquid inlet, the second low-temperature shut-off valve V02 is located in the branch pipe section between the first emergency shut-off valve PV01 and the second liquid inlet, and the sixth low-temperature shut-off valve is located in the branch pipe section between the first low-temperature shut-off valve V01 and the first low-temperature shut-off valve V02.

[0026] Example 3: Method for pressurizing L-CNG gas station tank

[0027] Determine the start-up status of the plunger pump return process. When the plunger pump return process is started, LNG enters the plunger pump from the bottom of the storage tank through pipeline three. Under the pressure of the plunger pump, high-pressure liquid is formed and flows into the next process equipment from the plunger pump outlet pipe. Before entering the plunger pump for pressurization, part of the LNG absorbs heat and vaporizes to form BOG. ​​BOG flows back to the gas phase port at the top of the storage tank through pipeline four. Close the third low-temperature stop valve V03 and the sixth low-temperature stop valve, open the fifth low-temperature stop valve V07, and the LNG in the storage tank enters the storage tank booster from the bottom of the storage tank through pipeline one. After absorbing the heat of the air in the storage tank booster and becoming gaseous, it enters the storage tank from the first liquid inlet at the top of the storage tank through the first branch pipe. The storage tank is pressurized; when the plunger pump return air process stops, either the third cryogenic stop valve V03 is opened and the fifth cryogenic stop valve V07 is closed, and the LNG in the storage tank enters the storage tank supercharger from the bottom of the storage tank through pipeline 1, absorbs the heat of the air in the storage tank supercharger to become a gas, and then enters the storage tank from the gas phase port on the top of the storage tank through the second branch pipe, and the storage tank is pressurized; or the third cryogenic stop valve V03 and the sixth cryogenic stop valve are closed, and the fifth cryogenic stop valve V07 is opened, and the LNG in the storage tank enters the storage tank supercharger from the bottom of the storage tank through pipeline 1, absorbs the heat of the air in the storage tank supercharger to become a gas, and then enters the storage tank from the first liquid inlet on the top of the storage tank through the first branch pipe, and the storage tank is pressurized.

[0028] By adopting the pressurizing system of the present invention, even when the operating liquid level of the storage tank is relatively low, there is no need to stop the operation of the plunger pump to pressurize the storage tank. The pressurizing and the plunger pump can operate normally at the same time to meet the gas filling demand during the peak period of gas filling, and there is no need to modify the interface of the storage tank, which not only does not affect the structural design of the storage tank and the overall vacuum effect, but also has low modification costs.

[0029] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, those skilled in the art can make a variety of similar expressions without violating the purpose and claims of the present invention, and such changes all fall within the protection scope of the present invention.

Claims

1. An optimized L-CNG filling station tank boosting system, comprising a plunger pump (1), a tank (2) and a booster (3) connected by pipelines, characterized in that: The liquid inlet of the supercharger (3) is connected to the first liquid outlet of the storage tank (2) through the first pipeline (4), and the gas outlet of the supercharger (3) is connected to the gas phase port and the first liquid inlet of the storage tank (2) through the second pipeline (5); The storage tank (2) is provided with a second liquid inlet, and the first liquid inlet and the second liquid inlet are connected to the same liquid inlet pipeline (6); The second pipeline (5) comprises a first branch pipe (51) and a second branch pipe (52), wherein the first branch pipe (51) is connected to the liquid inlet pipeline (6), and the second branch pipe is connected to the gas phase port of the storage tank (2); The liquid inlet of the plunger pump (1) is connected to the second liquid outlet of the storage tank (2) through the pipeline three (7), and the air return port of the plunger pump (1) is connected to the second branch pipe (52) through the pipeline four (8); The pipeline one (4), the first branch pipe (51), the second branch pipe (52), the pipeline three (7) and the pipeline four (8) are respectively provided with a second emergency shut-off valve (PV02), a fifth low-temperature shut-off valve (V07), a third low-temperature shut-off valve (V03), a third emergency shut-off valve (PV03) and a fourth low-temperature shut-off valve (V06); The liquid inlet pipeline (6) is provided with a first emergency shut-off valve (PV01), a first low-temperature shut-off valve (V01), a second low-temperature shut-off valve (V02) and a sixth low-temperature shut-off valve, wherein the first emergency shut-off valve (PV01) is located in the main pipe section of the liquid inlet pipeline (6), the first low-temperature shut-off valve (V01) is located in the branch pipe section between the first emergency shut-off valve (PV01) and the first liquid inlet, the second low-temperature shut-off valve (V02) is located in the branch pipe section between the first emergency shut-off valve (PV01) and the second liquid inlet, and the sixth low-temperature shut-off valve is located in the branch pipe section between the first low-temperature shut-off valve (V01) and the second low-temperature shut-off valve (V02); A method for optimizing the L-CNG filling station tank pressurization system comprises the following steps: S1. Determine the start-up status of the plunger pump air return process; S2. When the plunger pump air return process is started, close the third cryogenic shut-off valve (V03), open the fifth cryogenic shut-off valve (V07), and start the tank pressurization process; S3. When the plunger pump air return process stops, open the fifth cryogenic shut-off valve (V07) or the third cryogenic shut-off valve (V03) to start the tank pressurization process; S2 specifically includes: starting the plunger pump, LNG enters the plunger pump from the bottom of the storage tank through pipeline 3, and forms high-pressure liquid under the pressure of the plunger pump, and flows into the next process equipment from the liquid outlet pipe of the plunger pump. Before the LNG enters the plunger pump for pressure boosting, part of the LNG absorbs heat and gasifies to form BOG, and the BOG flows back to the gas phase port at the top of the storage tank through pipeline 4, closes the third low-temperature stop valve (V03) and the sixth low-temperature stop valve, and opens the fifth low-temperature stop valve (V07). The LNG in the storage tank enters the storage tank booster from the bottom of the storage tank through pipeline 1, absorbs air heat in the storage tank booster and becomes gaseous, and then enters the storage tank from the first liquid inlet at the top of the storage tank through the first branch pipe to pressurize the storage tank; S3 is specifically as follows: opening the third cryogenic stop valve (V03), closing the fifth cryogenic stop valve (V07), the LNG in the storage tank enters the storage tank supercharger from the bottom of the storage tank through pipeline 1, absorbs the heat of the air in the storage tank supercharger to become a gas, and then enters the storage tank from the gas phase port at the top of the storage tank through the second branch pipe to pressurize the storage tank; closing the third cryogenic stop valve (V03) and the sixth cryogenic stop valve, opening the fifth cryogenic stop valve (V07), the LNG in the storage tank enters the storage tank supercharger from the bottom of the storage tank through pipeline 1, absorbs the heat of the air in the storage tank supercharger to become a gas, and then enters the storage tank from the first liquid inlet at the top of the storage tank through the first branch pipe to pressurize the storage tank.

2. The optimized L-CNG filling station tank pressurization system according to claim 1, characterized in that: The bottom of the storage tank (2) is provided with the first liquid outlet, the second liquid outlet and the second liquid inlet, and the top of the storage tank (2) is provided with the gas phase port and the first liquid inlet.

3. The optimized L-CNG filling station tank pressurization system according to claim 1, characterized in that: An annular liquid inlet pipe (9) is provided in the storage tank (2). The annular liquid inlet pipe (9) is arranged close to the top of the storage tank (2). The liquid inlet end of the annular liquid inlet pipe (9) is connected to the first liquid inlet port. A plurality of nozzles are evenly distributed on the annular liquid inlet pipe (9).

Images