BOG treatment tool assembly and treatment method

Abstract

The invention discloses a BOG treatment tool assembly and a treatment method.The BOG treatment tool assembly comprises a BOG gas phase pipeline, a high-pressure natural gas pipeline, a medium-pressure natural gas pipeline and an injection pipe set, the injection pipe set is provided with an adjustable ejector, the injection pipe set is provided with a gas inlet end, a gas outlet end and a drainage end, the gas inlet end of the injection pipe set communicates with the high-pressure natural gas pipeline, the gas outlet end of the injection pipe set communicates with the medium-pressure natural gas pipeline, and the drainage end of the injection pipe set communicates with the medium-pressure natural gas pipeline; the drainage end of the injection pipe set is communicated with a BOG gas phase pipeline, and the gas outlet end of the injection pipe set is communicated with a medium-pressure natural gas pipeline. Therefore, the BOG gas in the BOG gas phase pipeline and the high-pressure natural gas in the high-pressure natural gas pipeline can be mixed by the adjustable ejector of the ejector pipe group to obtain medium-pressure natural gas, the medium-pressure natural gas is sent out by the medium-pressure natural gas pipeline in a medium-pressure natural gas well, and the BOG gas is sucked into the adjustable ejector. Power is not needed (the power depends on negative pressure generated when high-pressure natural gas in the adjustable ejector is jetted), and the mixing effect of a BOG gas phase and the high-pressure natural gas is good.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas transportation, and in particular relates to a BOG processing tooling assembly and a processing method. Background Art

[0002] According to different BOG treatment methods, the receiving stations currently in operation or under construction in China usually use three BOG treatment processes: BOG direct compression process, BOG recondensation process and BOG reliquefaction process. The BOG direct compression process is to pressurize the BOG generated in the LNG receiving station to the pressure of the external transmission pipeline network through a BOG low-pressure compressor or a high-pressure compressor. BOG enters the external transmission pipeline network in the form of high- and low-pressure natural gas for users. Its process energy consumption is determined by the compressor outlet pressure, and the higher the pipeline pressure, the higher the energy consumption. The BOG recondensation process generates corresponding energy consumption in both the recondensation and gasification processes. Compared with the direct compression process, the system energy consumption is reduced, but it still has the characteristics of high energy consumption. The BOG reliquefaction process is mainly used in situations where downstream supporting facilities have not been completed or there is no downstream market demand, resulting in the inability to gasify and export. It can neither generate economic value nor generate high equipment energy consumption. During the production and operation period, LNG receiving stations will generate a large amount of BOG due to factors such as operating conditions and heat leakage from the external environment. If this part of BOG is not recovered and processed in time, it may cause overpressure in the storage tank, resulting in safety hazards such as fire and explosion, or flare emissions causing huge waste of energy, which often leads to serious consequences. The BOG treatment process of LNG receiving stations has always been a difficult point in the industry. In addition, the three BOG treatment processes of BOG direct compression process, BOG re-condensation process and BOG re-liquefaction process all produce high equipment energy consumption. Summary of the invention

[0003] In order to solve the above technical problems, the object of the present invention is to provide a BOG processing tooling assembly with low energy consumption, small equipment investment and good operation safety.

[0004] In order to achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a BOG processing tooling assembly, comprising a BOG gas phase pipeline, a high-pressure natural gas pipeline, a medium-pressure natural gas pipeline and an ejector pipe group, the ejector pipe group having an adjustable ejector, the ejector pipe group having an air inlet end, an air outlet end and a drainage end, the air inlet end of the ejector pipe group being connected to the high-pressure natural gas pipeline, the drainage end of the ejector pipe group being connected to the BOG gas phase pipeline, and the air outlet end of the ejector pipe group being connected to the medium-pressure natural gas pipeline.

[0005] The beneficial effect of the above technical solution is that the adjustable ejector of the ejector pipe group can mix the BOG gas in the BOG gas phase pipeline and the high-pressure natural gas in the high-pressure natural gas pipeline to obtain medium-pressure natural gas, and the medium-pressure natural gas well is sent out through the medium-pressure natural gas pipeline, and the BOG gas is sucked into the adjustable ejector, which does not require power (the power depends on the negative pressure generated by the high-pressure natural gas jet in the adjustable ejector), and it has a good mixing effect of the BOG gas phase and the high-pressure natural gas.

[0006] In the above technical solution, there are multiple ejector tube groups.

[0007] The beneficial effect of the above technical solution is that the ejector tube group can be designed redundantly to ensure that at least one ejector tube group can operate normally.

[0008] In the above technical solution, a first valve is provided at the connection point between the medium-pressure natural gas pipeline and the gas outlet ends of the plurality of ejector tube groups.

[0009] The beneficial effect of the above technical solution is that the first valve can be used as the main air inlet valve of the medium-pressure natural gas pipeline.

[0010] The ejector pipe group in the above technical solution also includes an air bleed pipe, an air inlet pipe, an air outlet pipe and an air-temperature gasifier. The adjustable ejector has an air inlet, a flow outlet and an air outlet. The air inlet of the adjustable ejector is connected to the high-pressure natural gas pipeline through the air inlet pipe, the flow outlet of the adjustable ejector is connected to the BOG gas phase pipeline through the air bleed pipe, and the air outlet of the adjustable ejector is connected to the medium-pressure natural gas pipeline through the air outlet pipe. The air-temperature gasifier is connected to the air bleed pipe, and a second valve is provided at the inlet of the air-temperature gasifier, a third valve is provided at the outlet of the air-temperature gasifier, a fourth valve is provided on the air inlet pipe, and a fifth valve is provided on the air outlet pipe.

[0011] The beneficial effect of the above technical solution is that the fourth valve is used as the main inlet valve of the inlet pipe, and the fifth valve is used as the main outlet valve of the outlet pipe. Specifically, the BOG gas in the BOG gas phase pipeline in this embodiment can be heated by the air-temperature vaporizer and gasified into low-pressure gas at room temperature before being transported to the adjustable ejector, so that it can form medium-pressure natural gas after mixing with high-pressure natural gas.

[0012] In the above technical solution, a flow monitoring element, a temperature monitoring element, a safety valve, an emergency shut-off valve, a pressure monitoring element and a check valve are sequentially arranged on the air bleed pipe between the air-temperature gasifier and the adjustable ejector.

[0013] The beneficial effect of the above technical solution is that the flow, temperature and pressure values ​​on the air bleed pipe can be monitored in real time to ensure its safe operation. At the same time, the provision of a safety valve and an emergency shut-off valve can further ensure the safety of the operation of the air bleed pipe, and the provision of a check valve on the air bleed pipe can prevent high-pressure natural gas from overflowing into the BOG gas phase pipeline through the air bleed pipe.

[0014] In the above technical solution, the flow monitoring element is a flow sensor, the temperature monitoring element is a temperature sensor, the pressure monitoring element is a pressure sensor, and the fourth valve and the fifth valve are both electric valves.

[0015] The beneficial effect of the above technical solution is that it has a high degree of intelligence.

[0016] The above technical solution also includes a controller, and the flow monitoring element, temperature monitoring element, pressure monitoring element, fourth valve and fifth valve are all electrically connected to the controller.

[0017] The beneficial effect of the above technical solution is that it can further improve its automation and intelligence level.

[0018] In the above technical solution, two check valves are provided on the air duct.

[0019] The beneficial effect of the above technical solution is that: by arranging two check valves on the air duct, a redundant design can be realized, thereby preventing a single check valve from being damaged and causing high-pressure natural gas to overflow into the air duct.

[0020] The injection coefficient of the adjustable ejector described in the above technical solution is 0.065.

[0021] The beneficial effect of the above technical solution is that the injection coefficient enables the adjustable ejector to completely absorb the BOG gas vaporized by the air-temperature gasifier, thus making its processing efficiency high.

[0022] A second object of the present invention is to provide a method for treating BOG with low operating cost and based on the above BOG treatment tooling assembly.

[0023] In order to achieve the above-mentioned purpose, another technical solution of the present invention is as follows: a BOG treatment method based on the BOG treatment tooling assembly as described above, wherein the air-temperature gasifier gasifies the BOG gas with a temperature of -110°C in the BOG gas phase pipeline into a normal temperature low-pressure gas above 0°C, and transports it to the adjustable ejector to mix with the natural gas transported by the high-pressure natural gas pipeline and inject it into the medium-pressure natural gas pipeline.

[0024] The beneficial effect of the above technical solution is that the treatment method can only use the pressure energy of high-pressure natural gas as a power to suck the BOG gas into the adjustable ejector for mixing, and at the same time eject the mixed gas. The process flow is simple, the application is convenient, and it is safe and reliable. It can achieve the purpose of treating BOG in the receiving station, meet the needs of BOG treatment volume under different working conditions, and achieve BOG treatment effect; it also does not generate equipment energy consumption, saves costs, and generates greater economic benefits while being environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a result schematic diagram of the BOG treatment tooling assembly described in Example 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of the electrical connections of the controller described in Example 1 of the present invention.

[0027] In the figure: 1. BOG gas phase pipeline; 2. High-pressure natural gas pipeline; 3. Medium-pressure natural gas pipeline; 4. Ejector pipe group; 41. Adjustable ejector; 42. Air bleed pipe; 421. Flow monitoring element; 422. Temperature monitoring element; 423. Safety valve; 424. Emergency shut-off valve; 425. Pressure monitoring element; 426. Check valve; 43. Inlet pipe; 431. Fourth valve; 44. Outlet pipe; 441. Fifth valve; 45. Air-temperature vaporizer; 451. Second valve; 452. Third valve; 5. First valve; 6. Controller. DETAILED DESCRIPTION

[0028] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail by way of example with reference to the accompanying drawings in the following paragraphs. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0029] Example 1

[0030] like Figure 1As shown, this embodiment provides a BOG processing tool assembly, including a BOG gas phase pipeline 1, a high-pressure natural gas pipeline 2, a medium-pressure natural gas pipeline 3 and an ejector pipe group 4, wherein the ejector pipe group 4 has an adjustable ejector 41, and the ejector pipe group 4 has an air inlet end, an air outlet end and a drainage end. The air inlet end of the ejector pipe group 4 is connected to the high-pressure natural gas pipeline 2, the drainage end of the ejector pipe group 4 is connected to the BOG gas phase pipeline 1, and the air outlet end of the ejector pipe group 4 is connected to the medium-pressure natural gas pipeline 3. In this way, the adjustable ejector of the ejector pipe group can mix the BOG gas in the BOG gas phase pipeline with the high-pressure natural gas in the high-pressure natural gas pipeline to obtain medium-pressure natural gas, and the medium-pressure natural gas well is sent out through the medium-pressure natural gas pipeline, and the BOG gas is sucked into the adjustable ejector, which does not require power (the power depends on the negative pressure generated when the high-pressure natural gas in the adjustable ejector is jetted), and the mixing effect of the BOG gas phase and the high-pressure natural gas is good.

[0031] In the above technical solution, the ejector tube group 4 is provided with a plurality of ejector tube groups, so that the ejector tube group can be designed redundantly to ensure that at least one ejector tube group can operate normally. In this embodiment, two ejector tube groups can be provided.

[0032] In the above technical solution, a first valve 5 is provided at the connection point between the medium-pressure natural gas pipeline 3 and the gas outlet ends of the plurality of ejector tube groups 4, so that the first valve can be used as the main air inlet valve of the medium-pressure natural gas pipeline.

[0033] The ejector pipe group 4 in the above technical solution also includes an air bleed pipe 42, an air inlet pipe 43, an air outlet pipe 44 and an air-temperature gasifier 45. The adjustable ejector 41 has an air inlet, a flow outlet and an air outlet. The air inlet of the adjustable ejector 41 is connected to the high-pressure natural gas pipeline 2 through the air inlet pipe 43, the flow outlet of the adjustable ejector 41 is connected to the BOG gas phase pipeline 1 through the air bleed pipe 42, the air outlet of the adjustable ejector 41 is connected to the medium-pressure natural gas pipeline 3 through the air outlet pipe 44, the air-temperature gasifier 45 is connected to the air bleed pipe 42, and the air A second valve 451 is provided at the inlet of the temperature-type vaporizer 45, a third valve 452 is provided at the outlet of the air-temperature-type vaporizer 45, a fourth valve 431 is provided on the air inlet pipe 43, and a fifth valve 441 is provided on the air outlet pipe 44, so that the fourth valve serves as the main air inlet valve of the air inlet pipe, and the fifth valve serves as the main air outlet valve of the air outlet pipe. Specifically, in this embodiment, the BOG gas in the BOG gas phase pipeline can be heated and gasified into normal temperature and low pressure gas by the air-temperature-type vaporizer before being transported to the adjustable ejector, so that it can form medium pressure natural gas after mixing with high pressure natural gas.

[0034] In the above technical solution, the air bleed pipe 42 is provided with a flow monitoring element 421, a temperature monitoring element 422, a safety valve 423, an emergency shut-off valve 424, a pressure monitoring element 425 and a check valve 426 in sequence between the air-temperature gasifier 45 and the adjustable ejector 41, so that the flow, temperature and pressure values ​​on the air bleed pipe can be monitored in real time to ensure its safe operation. At the same time, the safety valve and the emergency shut-off valve can further ensure the safety of the operation of the air bleed pipe, and the check valve on the air bleed pipe can prevent the high-pressure natural gas from overflowing into the BOG gas phase pipeline through the air bleed pipe.

[0035] In the above technical solution, the flow monitoring element 421 is a flow sensor, the temperature monitoring element 422 is a temperature sensor, the pressure monitoring element 425 is a pressure sensor, and the fourth valve 431 and the fifth valve 441 are both electric valves, which makes it highly intelligent.

[0036] like Figure 2 As shown, the above technical solution also includes a controller 6, and the flow monitoring element 421, the temperature monitoring element 422, the pressure monitoring element 425, the fourth valve 431 and the fifth valve 441 are all electrically connected to the controller 6, so that its automation and intelligence level can be further improved. In this embodiment, the two ejector tube groups can share one controller 6, and the controller in this embodiment can adopt an ARM series single-chip microcomputer.

[0037] In the above technical solution, two check valves 426 are provided on the air bleed pipe 42. By providing two check valves on the air bleed pipe, a redundant design can be achieved to avoid the leakage of high-pressure natural gas into the air bleed pipe due to damage of a single check valve.

[0038] The injection coefficient of the adjustable ejector 41 in the above technical solution is 0.065, which enables the adjustable ejector to completely absorb the BOG gas vaporized by the air-temperature vaporizer, thereby increasing its processing efficiency (under this injection coefficient, the daily evaporated gas during the production and operation of the LNG receiving station can be effectively recovered, and the design daily evaporation rate of a 160,000 cubic meter LNG storage tank is usually 0.05%).

[0039] In this embodiment, the gas delivery pressure in the high-pressure natural gas pipeline 2 is about 8 MPa, while the gas delivery pressure in the medium-pressure gas pipeline is about 5 MPa.

[0040] For a single air bleed pipe group, when its corresponding flow monitoring element 421, temperature monitoring element 422 and pressure monitoring element 425 detect abnormal flow, temperature and pressure therein, the controller can control the corresponding fourth valve and fifth valve to adjust their opening and closing degrees. When the flow of high-pressure natural gas entering the adjustable ejector decreases, the flow of BOG gas delivered from the BOG gas phase pipeline will also decrease accordingly.

[0041] Example 2

[0042] This embodiment provides a BOG treatment method based on the BOG treatment tooling assembly as described in Example 1, wherein the air-temperature gasifier 45 gasifies the BOG gas at a temperature of -110°C in the BOG gas phase pipeline 1 into a normal temperature low-pressure gas above 0°C, and transports it to the adjustable ejector 41 to mix with the natural gas transported by the high-pressure natural gas pipeline 2 and eject it into the medium-pressure natural gas pipeline 3. This treatment method can only use the pressure energy of the high-pressure natural gas as a power to suck the BOG gas into the adjustable ejector for mixing, and at the same time eject the mixed gas. The process flow is simple, the application is convenient, and the mixed gas is safe and reliable. It not only achieves the purpose of treating the BOG in the receiving station, but also meets the requirements of the BOG treatment volume under different working conditions and achieves the BOG treatment effect; it also does not generate equipment energy consumption, saves costs, and generates greater economic benefits while being environmentally friendly.

[0043] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in the industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with the profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A BOG treatment tooling assembly, characterized in that: The invention comprises a BOG gas phase pipeline (1), a high-pressure natural gas pipeline (2), a medium-pressure natural gas pipeline (3) and an ejector pipe group (4), wherein the ejector pipe group (4) has an adjustable ejector (41), the ejector pipe group (4) has an air inlet end, an air outlet end and a drainage end, the air inlet end of the ejector pipe group (4) is connected to the high-pressure natural gas pipeline (2), the drainage end of the ejector pipe group (4) is connected to the BOG gas phase pipeline (1), and the air outlet end of the ejector pipe group (4) is connected to the medium-pressure natural gas pipeline (3).

2. The BOG treatment tooling assembly according to claim 1, characterized in that: A plurality of ejector tube groups (4) are provided.

3. The BOG treatment tooling assembly according to claim 2, characterized in that: A first valve (5) is provided at the connection point between the medium-pressure natural gas pipeline (3) and the gas outlet ends of the plurality of ejector tube groups (4).

4. The BOG treatment tooling assembly according to any one of claims 1 to 3, characterized in that: The ejector pipe group (4) further comprises an air bleed pipe (42), an air inlet pipe (43), an air outlet pipe (44) and an air temperature type gasifier (45); the adjustable ejector (41) comprises an air inlet, a flow outlet and an air outlet; the air inlet of the adjustable ejector (41) is connected to the high-pressure natural gas pipeline (2) through the air inlet pipe (43); the flow outlet of the adjustable ejector (41) is connected to the BOG gas phase pipeline (1) through the air bleed pipe (42); The gas outlet of the gasifier (41) is connected to the medium-pressure natural gas pipeline (3) through the gas outlet pipe (44), the air-temperature gasifier (45) is connected to the air bleed pipe (42), and a second valve (451) is provided at the inlet of the air-temperature gasifier (45), a third valve (452) is provided at the outlet of the air-temperature gasifier (45), a fourth valve (431) is provided on the gas inlet pipe (43), and a fifth valve (441) is provided on the gas outlet pipe (44).

5. The BOG treatment tooling assembly according to claim 4, characterized in that: A flow monitoring element (421), a temperature monitoring element (422), a safety valve (423), an emergency shut-off valve (424), a pressure monitoring element (425) and a check valve (426) are sequentially arranged on the air bleed pipe (42) between the air-temperature vaporizer (45) and the adjustable ejector (41).

6. The BOG treatment tooling assembly according to claim 5, characterized in that: The flow monitoring element (421) is a flow sensor, the temperature monitoring element (422) is a temperature sensor, the pressure monitoring element (425) is a pressure sensor, and the fourth valve (431) and the fifth valve (441) are both electric valves.

7. The BOG treatment tooling assembly according to claim 5, characterized in that: It also includes a controller (6), and the flow monitoring element (421), the temperature monitoring element (422), the pressure monitoring element (425), the fourth valve (431) and the fifth valve (441) are all electrically connected to the controller (6).

8. The BOG treatment tooling assembly according to claim 4, characterized in that: Two check valves (426) are provided on the air bleed pipe (42).

9. The BOG treatment tooling assembly according to claim 4, characterized in that: The injection coefficient of the adjustable ejector (41) is 0.

065.

10. A BOG treatment method based on the BOG treatment tooling assembly according to any one of claims 4 to 9, characterized in that: The air-temperature gasifier (45) gasifies the BOG gas at a temperature of -110°C in the BOG gas phase pipeline (1) into a low-pressure gas at a normal temperature above 0°C, and transports the gas to the adjustable ejector (41) to mix with the natural gas transported by the high-pressure natural gas pipeline (2) and then eject the gas into the medium-pressure natural gas pipeline (3).

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