Multifunctional refrigerant unloading and light hydrocarbon loading device and process

Abstract

The invention relates to a multifunctional refrigerant unloading and light hydrocarbon loading device and process. The device comprises a multifunctional loading and unloading arm, an ethane unloading pipeline, an isopentane unloading pipeline, an ethylene pressurizing pipeline, an ethylene unloading pipeline, a light hydrocarbon recovery pipeline, a nitrogen inlet pipeline, a nitrogen purging and emptying pipeline and the like. The invention develops a multifunctional refrigerant unloading and light hydrocarbon loading process and device according to the field environment and the use condition of a liquefaction factory, and is suitable for the working condition of a conventional liquefaction factory. The device is provided with two sets of loading and unloading vehicle arms, one set of low-temperature loading and unloading vehicle arms can be used for unloading ethane, isopentane and ethylene refrigerants, and one set of normal-temperature arm is used for loading light hydrocarbon. The whole device is automatically controlled according to temperature and pressure detection, and the occupied area is reduced by three fourths.

Description

TECHNICAL FIELD

[0001] The present application relates to a multifunctional refrigerant (ethane, isopentane and ethylene) unloading and light hydrocarbon loading device and process suitable for LNG liquefaction plants, which can realize automatic refrigerant (ethane, isopentane and ethylene) unloading and light hydrocarbon loading functions. BACKGROUND

[0002] At present, most of the LNG liquefaction stations use MRC liquefaction process, which has simple process flow and low energy consumption, and is used in various LNG liquefaction processes. In the MRC mixed refrigeration, methane, ethane, isopentane, ethylene and nitrogen are usually used. Methane and nitrogen are usually obtained in the station, while ethane, isopentane and ethylene need to be transported to the LNG liquefaction station by tank truck alone, because a separate refrigerant unloading device is needed for unloading. Conventional refrigerant unloading requires different unloading arms to be used according to the medium temperature. Moreover, in the natural gas medium component, there are usually C3 and above light hydrocarbon components, which need to be removed in the liquefaction process. The removed light hydrocarbon can be recycled to improve the utilization value of natural gas, so a separate light hydrocarbon recovery and loading device needs to be set up and transported to other use scenarios by tank truck. SUMMARY

[0003] To solve the above technical problems, the present application provides a multifunctional refrigerant unloading and light hydrocarbon loading device, which includes a set of refrigerant unloading arms, a set of light hydrocarbon loading arms, an ethylene booster, an ethane unloading pump and an isopentane unloading pump. The tank truck gas phase interface is connected to the gas phase inlet of the refrigerant unloading arm, the gas phase outlet of the refrigerant unloading arm is connected to the first refrigerant unloading gas phase pipeline, the first refrigerant unloading gas phase pipeline is branched into two branch pipes, i.e., the second refrigerant unloading gas phase pipeline and the ethylene gas phase pipeline, the second refrigerant unloading gas phase pipeline is branched into the ethane gas phase return pipeline and the isopentane gas phase return pipeline, the other end of the ethane gas phase return pipeline is connected to the ethane storage tank gas phase interface, the other end of the isopentane gas phase return pipeline is connected to the isopentane storage tank gas phase interface, and the other end of the ethylene gas phase pipeline is connected to the ethylene storage tank gas phase interface. The liquid phase interface of the tank car is connected with the liquid phase inlet of the refrigerant unloading arm, the liquid phase outlet of the refrigerant unloading arm is connected with the first refrigerant unloading liquid phase pipeline, the first refrigerant unloading liquid phase pipeline is branched into three branches, i.e., the second refrigerant unloading liquid phase pipeline, the ethylene unloading liquid phase pipeline and the ethylene booster liquid phase pipeline, one end of the ethylene booster liquid phase pipeline is connected with the first refrigerant unloading liquid phase pipeline, and the other end is connected with the ethylene booster; the pipeline is branched from the liquid phase of the loading and unloading arm, ethylene comes out of the liquid phase arm of the loading and unloading arm, enters the ethylene booster to be gasified, and then boosts the tank car; the outlet pipeline of the ethylene booster is connected with the ethylene gas phase pipeline, the liquid phase ethylene is gasified by the ethylene booster, and then returns to the ethylene tank car through the ethylene gas phase pipeline to boost the tank car; the connection point of the outlet pipeline of the ethylene booster and the ethylene gas phase pipeline is connected with the low-temperature emission gas pipeline, and the first safety valve is arranged on the low-temperature emission gas pipeline; when the ethylene gas phase pipeline is overpressure, the overpressure gas is discharged through the first safety valve of the low-temperature emission gas pipeline; The second refrigerant unloading liquid phase pipeline is branched into two branches, i.e., the ethane unloading liquid phase pipeline and the isopentane unloading liquid phase pipeline; the ethane unloading liquid phase pipeline and the isopentane unloading liquid phase pipeline are respectively connected with the liquid phase interface of the ethane storage tank and the isopentane storage tank; the ethane unloading liquid phase pipeline is provided with an ethane unloading pump; the ethane unloading pump return gas pipeline (branched from the return gas port of the ethane unloading pump) is connected with the ethane gas phase return gas pipeline; when the pump is running, the gas in the ethane pump is discharged into the ethane gas phase return gas pipeline through the pipeline by pressure detection; the isopentane unloading liquid phase pipeline is provided with an isopentane unloading pump; after being opened, the isopentane is unloaded from the tank car to the isopentane storage tank; the isopentane unloading pump return gas pipeline (branched from the return gas port of the isopentane unloading pump) is connected with the isopentane gas phase return gas pipeline; when the pump is running, the gas in the isopentane unloading pump is discharged into the isopentane gas phase return gas pipeline through the pipeline by pressure detection; One end of the refrigerant unloading arm purging return gas pipeline is connected with the liquid phase and gas phase nitrogen interfaces of the refrigerant unloading arm, and the other end is connected with the field station emission gas pipeline to the flare; One end of the refrigerant unloading arm nitrogen inlet pipeline is connected with the field station nitrogen inlet pipeline, and the other end is connected with the liquid phase and gas phase nitrogen interfaces of the refrigerant unloading arm; One end of the nitrogen inlet pipeline is connected with the field station nitrogen inlet pipeline, and the other end is connected with the liquid phase and gas phase nitrogen interfaces of the refrigerant unloading arm; The light hydrocarbon loading liquid phase pipeline and the light hydrocarbon gas phase return gas pipeline are respectively connected with the liquid phase interface and the gas phase interface of the light hydrocarbon loading arm; the other ends of the gas phase interface and the liquid phase interface of the light hydrocarbon loading arm are connected with the gas phase outlet and the liquid phase outlet of the light hydrocarbon storage tank; the light hydrocarbon storage tank is a field station light hydrocarbon recovery storage tank, and is usually a C3+ hydrocarbon storage tank; One end of the light hydrocarbon loading arm purging return gas pipeline is connected with the liquid phase and gas phase nitrogen interfaces of the light hydrocarbon unloading arm, and the other end is connected with the field station emission gas pipeline to the flare; The ethylene unloading liquid phase pipeline is connected with the low-temperature release gas pipeline through an ethylene unloading liquid phase overpressure release pipeline drawn from the ethylene unloading liquid phase pipeline (the connection is located downstream of the first safety valve, i.e. on the side far from the ethylene booster), and the ethylene unloading liquid phase overpressure release pipeline is provided with a second safety valve.

[0004] Further, a normal-temperature release gas pipeline is drawn from the light hydrocarbon loading liquid phase pipeline, and the normal-temperature release gas pipeline is provided with a third safety valve.

[0005] Preferably, the ethane gas phase return gas pipeline is provided with a first temperature transmitter, and the first temperature transmitter is provided with a first valve and a second valve on the two sides thereof.

[0006] Preferably, a second temperature transmitter is arranged upstream of the ethane unloading pump on the ethane unloading liquid phase pipeline, a third valve and a fourth valve are arranged on the two sides of the second temperature transmitter, a first pressure transmitter is arranged downstream of the ethane unloading pump on the ethane unloading liquid phase pipeline, and a first check valve and a fifth valve are arranged on the two sides of the first pressure transmitter.

[0007] Preferably, a third temperature transmitter is arranged on the isopentane gas phase return gas pipeline, a seventh valve and an eighth valve are arranged on the two sides of the third temperature transmitter, and the eighth valve is located downstream of the connection point of the isopentane unloading pump return gas pipeline and the isopentane gas phase return gas pipeline (i.e. on the side far from the isopentane storage tank).

[0008] Preferably, a fourth temperature transmitter is arranged upstream of the isopentane unloading pump on the isopentane unloading liquid phase pipeline, a tenth valve and an eleventh valve are arranged on the two sides of the fourth temperature transmitter, a second pressure transmitter is arranged downstream of the isopentane unloading pump on the isopentane unloading liquid phase pipeline, and a second check valve and a twelfth valve are arranged on the two sides of the second pressure transmitter.

[0009] Preferably, upstream pipelines of the ethane unloading pump and the isopentane unloading pump (i.e. the ethane unloading liquid phase pipeline between the fourth valve and the ethane unloading pump and the isopentane unloading liquid phase pipeline between the eleventh valve and the isopentane unloading pump) can be respectively provided with a first pipeline filter and a second pipeline filter, which are arranged for the ethane unloading pump and the isopentane unloading pump to avoid impurities in the pipelines from entering the pump body and damaging the pump.

[0010] Preferably, a third pressure transmitter is arranged downstream of the connection point of the outlet pipeline of the ethylene booster and the ethylene gas phase pipeline (on the side far from the ethylene storage tank) on the ethylene gas phase pipeline, the third pressure transmitter is provided with a thirteenth valve and a third check valve on the two sides thereof, and a twenty-seventh valve is arranged upstream of the connection point of the outlet pipeline of the ethylene booster and the ethylene gas phase pipeline on the ethylene gas phase pipeline.

[0011] Preferably, a fourteenth valve is arranged on the ethylene booster liquid phase pipeline.

[0012] Preferably, the sixteenth valve and the fourth check valve are arranged on the ethylene unloading liquid phase pipeline (upstream position of the ethylene unloading liquid phase overpressure release pipeline).

[0013] Preferably, the seventeenth valve is arranged on the hydrocarbon gas phase return pipeline.

[0014] Preferably, the eighteenth valve, the fourth pressure transmitter and the flow meter are arranged on the light hydrocarbon loading liquid phase pipeline in sequence along the flow direction.

[0015] Preferably, the nineteenth valve and the fifth check valve are arranged on the nitrogen inlet pipeline in sequence.

[0016] Preferably, the twenty-fifth valve and the seventh check valve are arranged on the refrigerant unloading arm nitrogen inlet pipeline in sequence.

[0017] Preferably, the twenty-fourth valve and the twenty-third valve are arranged on the second refrigerant unloading liquid phase pipeline in sequence, and the twenty-fourth valve is used for nitrogen replacement refrigerant unloading arm liquid phase arm and first refrigerant unloading liquid phase pipeline residual medium purge venting when unloading, and the twenty-third valve is closed at this time to prohibit ethylene from entering the ethane and isopentane pipelines.

[0018] Preferably, the twenty-sixth valve and the eighth check valve are arranged on the refrigerant unloading arm purge return pipeline, and the twentieth valve and the sixth check valve are arranged on the light hydrocarbon loading arm purge return pipeline.

[0019] There are two sets of loading and unloading arms, one set is used for refrigerant unloading, and the other set is used for light hydrocarbon loading. The refrigerant unloading arm includes a liquid phase arm and a gas phase arm. One end of the liquid phase arm is connected with the ethane, isopentane and ethylene liquid inlet pipeline and the ethylene booster liquid phase pipeline (the other end of the liquid inlet pipeline is connected with the storage tank of the liquefied factory station), and the other end is connected with the tank car liquid phase outlet. One end of the gas phase arm (BOG return gas arm) is connected with the tank car BOG outlet, and the other end is connected with the BOG return pipeline (the ethane gas phase return pipeline, the isopentane gas phase return pipeline, the second refrigerant unloading gas phase pipeline (further connected with the ethane gas phase return pipeline and the isopentane gas phase return pipeline), the ethylene gas phase pipeline).

[0020] The application further provides a multifunctional refrigerant unloading and light hydrocarbon loading process using the above device, which comprises the following steps: The ethylene unloading process includes the pipeline replacement process, the tank car booster process and the ethylene unloading process.

[0021] Ethylene pipeline replacement process: the unloading arm is connected with the ethane tank car gas phase and liquid phase, the ethylene unloading process is started, the twenty-fifth valve on the refrigerant unloading arm nitrogen inlet pipeline and the twenty-fourth valve on the second refrigerant unloading liquid phase pipeline are opened, the twenty-fifth valve is opened to allow nitrogen to enter the refrigerant unloading arm, and the twenty-fourth valve is opened to allow other media that may be left in the pipeline to be emptied, and the ethane and isopentane concentrations are detected from the valve, during unloading, the twenty-fourth valve is used for nitrogen replacement and liquid phase arm and liquid phase pipeline residual medium purging and emptying, the twenty-third valve on the second refrigerant unloading liquid phase pipeline is closed at this time, ethylene is prohibited from entering the ethane and isopentane pipeline, the first refrigerant unloading liquid phase pipeline and the second refrigerant unloading liquid phase pipeline are purged and replaced (purge gas comes from the gas station nitrogen pipeline, enters the refrigerant unloading arm liquid phase arm and the first refrigerant unloading liquid phase pipeline through the refrigerant unloading arm nitrogen inlet pipeline, at this time the twenty-third valve / fourteenth valve / sixteenth valve are all in the closed state, the twenty-fourth valve is opened for discharge and replacement, and the concentration is detected at the same time). When the ethane, isopentane and other concentrations are ≤0.1%, the valves twenty-fourth valve and twenty-fifth valve are closed, the pipeline replacement is completed, and the tank car pressurization process is started.

[0022] Tank car pressurization process and ethylene unloading process: after the pipeline replacement process is completed, the thirteenth valve on the ethylene gas phase pipeline and the fourteenth valve on the ethylene pressurization liquid phase pipeline are automatically opened, ethylene enters the ethylene pressurizer, at this time the liquid phase ethylene enters the ethylene pressurizer through the first refrigerant unloading liquid phase pipeline and the ethylene pressurization liquid phase pipeline, exchanges heat with air, and is gasified into gaseous ethylene, returns to the tank car through the ethylene gas phase pipeline and the refrigerant unloading arm gas phase arm, and pressurizes the tank car, at this time the twenty-seventh valve on the ethylene gas phase pipeline is in the closed state, the tank car pressurization process is started, when the third pressure transmitter pipeline pressure of the ethylene gas phase pipeline is ≥0.5MPa, the sixteenth valve on the ethylene unloading liquid phase pipeline is automatically opened, the thirteenth valve on the ethylene gas phase pipeline and the fourteenth valve on the ethylene pressurization liquid phase pipeline remain in the open state, ethylene enters the ethylene storage tank through the ethylene unloading liquid phase pipeline, at this time the pressurization and unloading are carried out simultaneously, during the unloading process, when the third pressure transmitter pressure of the ethylene gas phase pipeline is <0.3MPa, the sixteenth valve on the ethylene unloading liquid phase pipeline is automatically closed, the unloading is stopped, and the pressurization of the tank car is continued, when the third pressure transmitter pressure is ≥0.5MPa, the sixteenth valve is automatically opened, and this is repeated until the unloading is completed when the third pressure transmitter pressure is <0.25MPa.

[0023] In the pressurization process, when the first safety valve pressure on the low-temperature emission gas pipeline is ≥1.0MPa, the first safety valve is automatically opened to emit and protect the unloading device.

[0024] When the pressure of the second safety valve on the ethylene unloading liquid overpressure relief pipeline in the unloading process is ≥1.0 MPa, the second safety valve is automatically opened for relief, protecting the unloading device.

[0025] Ethane unloading process: including pipeline replacement process and ethane unloading process.

[0026] Ethane pipeline replacement process: the unloading arm connects the ethane tank car gas phase and liquid phase, and the ethane unloading process is started. The twenty-fifth valve on the nitrogen inlet pipeline of the refrigerant unloading arm and the twenty-fourth valve on the second refrigerant unloading liquid phase pipeline are opened, and the first refrigerant unloading liquid phase pipeline and the second refrigerant unloading liquid phase pipeline are purged and replaced with nitrogen. The twenty-fifth valve is opened to allow nitrogen to enter the refrigerant unloading arm, and the twenty-fourth valve is opened to allow other media that may be left in the pipeline to be emptied. At the same time, the ethylene and isopentane concentrations are detected from the valve. When the concentrations of ethylene, isopentane, etc. are ≤0.1%, the twenty-fourth valve and the twenty-fifth valve are closed, and the pipeline replacement is completed. During the replacement process, if the temperature of any one of the first to fourth temperature transmitters on the ethane gas phase return gas pipeline, the ethane unloading liquid phase pipeline, the isopentane gas phase return gas pipeline, and the isopentane unloading liquid phase pipeline is ≤-10℃, the unloading program is automatically stopped. When the temperature in the pipeline is ≤-10℃ during operation, it indicates that the first valve, the third valve, the seventh valve, and the tenth valve have internal leakage. To protect the ethane gas phase return gas pipeline, the ethane unloading liquid phase pipeline, the isopentane gas phase return gas pipeline, the isopentane unloading liquid phase pipeline, and other pipelines at room temperature, and the equipment on the pipelines, the device process is automatically stopped. After checking that the equipment is not faulty, the process can be restarted. After no fault, the ethylene and isopentane concentrations are ≤0.1%, and the temperature of any one of the first to fourth temperature transmitters is >-10℃, the ethane unloading process is started.

[0027] Ethane unloading process: after the displacement is completed, the ethane unloading process is automatically started, the twenty-third valve on the second refrigerant unloading liquid phase pipeline, the first valve, the second valve on the ethane gas phase return gas pipeline, the third valve, the fourth valve and the fifth valve on the ethane unloading liquid phase pipeline are opened for a few seconds, for example, 5 seconds, and then the ethane unloading pump is automatically started. After the ethane unloading pump is started, the ethane is pressurized by the ethane unloading pump and then enters the ethane storage tank through the ethane unloading liquid phase pipeline. The ethane unloading pump return gas pipeline is the ethane unloading pump return gas pipeline. When the pump is running, the gas in the ethane pump is discharged into the ethane gas phase return gas pipeline through the pipeline. The ethane unloading liquid phase pipeline starts to unload ethane to the ethane storage tank. When the first pressure sensor on the ethane unloading liquid phase pipeline detects that the pressure is greater than or equal to 7 barg, the sixth valve on the ethane unloading pump return gas pipeline is opened (the ethane enters the ethane gas phase return gas pipeline to discharge the gas in the pump). When the first pressure sensor detects that the pressure is less than 5 barg, the sixth valve is closed. When the first pressure sensor detects that the pressure is less than 3 barg, the unloading is completed, the ethane unloading pump is closed, and the sixth valve is opened (the sixth valve is opened to release the load, which facilitates the next time the pump starts. If the sixth valve is closed, the next time the pump starts, the pressure will be detected and the pump cannot be started). After a few minutes, for example, 5 minutes, all the valves except the fifth valve (the fifth valve is a normally open valve) on the ethane unloading liquid phase pipeline are closed, and the ethane unloading is completed.

[0028] The isopentane unloading process is the same as the ethane unloading process.

[0029] Isopentane unloading process: including pipeline displacement process and ethane-isopentane unloading process.

[0030] Isopentane pipeline displacement process: the unloading arm is connected to the ethane tank car gas phase and liquid phase, and the isopentane unloading process is started. The twenty-fifth valve on the refrigerant unloading arm nitrogen inlet pipeline and the twenty-fourth valve on the second refrigerant unloading liquid phase pipeline are opened, and the first refrigerant unloading liquid phase pipeline and the second refrigerant unloading liquid phase pipeline are purged and displaced with nitrogen. When the concentration of ethylene, ethane, etc. is less than or equal to 0.1%, the twenty-fourth valve and the twenty-fifth valve are closed, and the pipeline displacement is completed. During the displacement process, if any one of the first to fourth temperature transmitters is less than or equal to -10℃, the unloading program is automatically stopped (when the pipeline temperature is less than or equal to -10℃ during operation, it indicates that the first valve, the third valve, the seventh valve and the tenth valve have internal leakage, in order to protect the ethane gas phase return gas pipeline, the ethane unloading liquid phase pipeline, the isopentane gas phase return gas pipeline and the isopentane unloading liquid phase pipeline at room temperature, and the equipment on the pipeline, the device process is automatically stopped. After checking that the equipment is not faulty, the process can be restarted), and if any one of the first to fourth temperature transmitters is greater than -10℃, the isopentane unloading process is started.

[0031] Isopentane unloading process: after the displacement is completed, the isopentane unloading process is automatically started, the twenty-third valve on the second refrigeration refrigerant unloading liquid phase pipeline, the seventh valve, the eighth valve on the isopentane gas phase return gas pipeline, the tenth valve, the eleventh valve, the twelfth valve on the isopentane unloading liquid phase pipeline are opened for a few seconds, for example, 5 seconds, and then the isopentane unloading pump is automatically started (after the isopentane unloading pump is started, isopentane is unloaded from the tank truck to the isopentane storage tank. The pump is installed on the isopentane unloading liquid phase pipeline, and the isopentane unloading pump return gas pipeline is connected with the isopentane gas phase return gas pipeline. During unloading, the second pressure sensor pressure of the isopentane unloading liquid phase pipeline is detected to be normal, the ninth valve on the isopentane unloading pump return gas pipeline is automatically closed, the tenth valve, the eleventh valve, and the twelfth valve are automatically opened, and the isopentane unloading pump starts to pressurize to transport isopentane to the isopentane storage tank through the isopentane unloading liquid phase pipeline), and the isopentane unloading liquid phase pipeline starts to unload isopentane to the isopentane storage tank. When the second pressure sensor detects that the pressure is greater than or equal to 7 barg, the ninth valve is opened (isopentane enters the isopentane gas phase return gas pipeline, and the gas in the pump is discharged); when the second pressure sensor detects that the pressure is less than 5 barg, the ninth valve is closed. When the second pressure sensor detects that the pressure is less than 3 barg, the unloading is completed, the isopentane unloading pump is closed, and the ninth valve is opened (in order to unload, the pump is started in an empty state next time). After a few minutes, for example, 5 minutes, all the valves are closed except the twelfth valve (the twelfth valve is a normally open valve) on the isopentane unloading liquid phase pipeline, and the isopentane unloading is completed.

[0032] Light hydrocarbon loading process: the pipeline displacement process and the light hydrocarbon loading process are included.

[0033] Light hydrocarbon pipeline displacement process: the light hydrocarbon tank truck gas phase and liquid phase are connected through the loading arm, and the light hydrocarbon loading process is started. The nineteenth valve on the nitrogen inlet pipeline and the twentieth valve on the light hydrocarbon loading arm purge return gas pipeline are opened, nitrogen enters the light hydrocarbon loading arm gas phase arm and liquid phase arm through the nitrogen inlet pipeline, the nineteenth valve and the twentieth valve are automatically closed after ten seconds, for example, 15 seconds, and the displacement is completed.

[0034] Light hydrocarbon loading process: after the displacement is completed, the eighteenth valve on the light hydrocarbon loading liquid phase pipeline is automatically opened, and the light hydrocarbon starts to be measured through the flowmeter. When the loading flow reaches the set value, the eighteenth valve is automatically closed, and the loading is completed after the light hydrocarbon pipeline displacement process is repeatedly started. During the loading process, when the third safety valve on the normal temperature diffused gas pipeline is greater than or equal to 1.4 MPa, the third safety valve is automatically opened to diffuse and protect the loading device. During the light hydrocarbon loading process, the hydrocarbon gas phase return gas pipeline is a return gas pipeline. When the tank truck is connected with the device, the seventeenth valve on the hydrocarbon gas phase return gas pipeline is automatically opened to discharge the BOG gas of the tank truck, so as to reduce the pressure of the tank truck and ensure that the liquid phase light hydrocarbon enters the tank truck.

[0035] Advantages of the present application: (1) A set of unloading arms is used to complete the unloading functions of ethane, isopentane and ethylene. Automatic switching is performed through process pipeline connection and valve control. Nitrogen is purged before each unloading to ensure that there is no other medium in the pipeline, to ensure the purity and safety of the refrigerant, and to avoid the freezing of the pipeline caused by the residual ethane and isopentane when ethylene is unloaded.

[0036] (2) The integrated isopentane unloading and light hydrocarbon loading design is integrated on the left and right sides of two loading and unloading arms, and a loading and unloading island is shared, so that the land area is reduced by three quarters.

[0037] (3) The refrigerant unloading booster has the same principle as the LNG unloading booster, but the working conditions are different. When unloading LNG, continuous unloading of multiple tank cars is required, and the rapidity of the booster needs to be ensured, so a separate booster arm is designed for boosting during unloading to ensure that unloading and boosting are performed simultaneously. Ethylene unloading is usually the first unloading of ethylene before use or the replenishment of ethylene at a later stage, and the required amount is small, so there is no great requirement for unloading time. In order to reduce equipment investment, the invention designs a booster and unloading arm and pipeline. When boosting, ethylene enters the booster pipeline and the unloading pipeline through the liquid phase arm pipeline at the same time, and when the pressure is lower than 0.3 barg, only the booster pipeline valve is opened and the unloading pipeline valve is closed. When the pressure is boosted to 0.5 barg, the unloading pipeline valve is opened and the ethylene unloading process is performed. During operation, when the pressure is again lower than 0.3 barg, the unloading pipeline valve is closed and boosting to 0.5 barg is started, and then the unloading pipeline valve is opened. This is repeated until unloading is completed. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The figure is a schematic diagram of the multifunctional refrigerant unloading and light hydrocarbon recovery device of the invention.

[0039] Reference signs: L1: refrigerant unloading arm purge return gas line; L2: ethane gas phase return gas line; L3: ethane unloading liquid phase line; L4: isopentane gas phase return gas line; L5 isopentane unloading liquid phase line; L6: low temperature release gas line; L7: ethylene gas phase line; L8: ethylene unloading liquid phase line; L9: normal temperature release gas line; L10: light hydrocarbon loading arm purge return gas line; L11: nitrogen inlet gas line; L12: light hydrocarbon loading liquid phase line; L13: light hydrocarbon gas phase return gas line; L14: refrigerant unloading arm nitrogen inlet gas line; L15: first refrigerant unloading liquid phase line; L16: first refrigerant unloading gas phase line; L17: second refrigerant unloading liquid phase line; L18: second refrigerant unloading gas phase line; L19: ethylene booster liquid phase line; L20: ethane unloading pump return gas line (pump gas phase recovery when ethane is unloaded); L21: isopentane unloading return gas line (pump gas phase recovery when isopentane is unloaded); L22: ethylene unloading liquid phase overpressure release line; ZXB1: refrigerant unloading arm; ZXB1-1: refrigerant unloading arm gas phase interface; ZXB1-2: refrigerant unloading arm liquid phase interface; ZXB2: light hydrocarbon loading arm; ZXB2-1: light hydrocarbon loading arm gas phase interface; ZXB2-2: light hydrocarbon loading arm liquid phase interface; F1: flow meter; SV1-SV3: first to third safety valves; V1-V26: first to twenty-sixth valves; ZH1-ZH8: first to eighth check valves; G1: first pipe filter; G2: second pipe filter; P1-P3: first to third pressure transmitters; T1-T4: first to fourth temperature transmitters. DETAILED DESCRIPTION

[0040] The present application provides a refrigerant (ethane, isopentane and ethylene) unloading and light hydrocarbon loading device and process suitable for LNG liquefaction plant, which is automatically controlled and adjusted according to the process, and meets the refrigerant unloading and light hydrocarbon loading of the liquefaction plant station. When the tank car is unloaded and loaded, the automatic cut-off valve automatically switches the process pipeline to start the unloading or loading process.

[0041] According to the first embodiment of the present application, the present application provides a multifunctional refrigerant unloading and light hydrocarbon loading device, which comprises a set of refrigerant unloading arm ZXB1, a set of light hydrocarbon loading arm ZXB2, ethylene booster A1, ethane unloading pump PB1, isopentane unloading pump PB2; The gaseous phase inlet of the tank car refrigerant unloading arm ZXB1 is connected with the gaseous phase interface of the tank car, and the gaseous phase outlet of the refrigerant unloading arm ZXB1 is connected with the first refrigerant unloading gaseous phase pipeline L16, the first refrigerant unloading gaseous phase pipeline L16 is branched into two branch pipelines, i.e., the second refrigerant unloading gaseous phase pipeline L18 and the ethylene gaseous phase pipeline L7, the second refrigerant unloading gaseous phase pipeline L18 is branched into the ethane gaseous phase return pipeline L2 and the isopentane gaseous phase return pipeline L4, the other end of the ethane gaseous phase return pipeline L2 is connected with the gaseous phase interface of the ethane storage tank, the other end of the isopentane gaseous phase return pipeline L4 is connected with the gaseous phase interface of the isopentane storage tank, and the other end of the ethylene gaseous phase pipeline L7 is connected with the gaseous phase interface of the ethylene storage tank; The liquid phase inlet of the tank car refrigerant unloading arm ZXB1 is connected with the liquid phase interface of the tank car, and the liquid phase outlet of the refrigerant unloading arm ZXB1 is connected with the first refrigerant unloading liquid phase pipeline L15, the first refrigerant unloading liquid phase pipeline L15 is branched into three branch pipelines, i.e., the second refrigerant unloading liquid phase pipeline L17, the ethylene unloading liquid phase pipeline L8 and the ethylene booster liquid phase pipeline L19, one end of the ethylene booster liquid phase pipeline L19 is connected with the first refrigerant unloading liquid phase pipeline L15, the other end of the ethylene booster liquid phase pipeline L19 is connected with the ethylene booster A1 (the pipeline is branched from the liquid phase of the loading and unloading arm, ethylene is discharged from the liquid phase of the loading and unloading arm, enters the ethylene booster to be gasified, and then pressurizes the tank car), the outlet pipeline of the ethylene booster A1 is connected with the ethylene gaseous phase pipeline L7, the ethylene gaseous phase pipeline L7 is further connected with the ethylene tank car, the liquid phase ethylene is gasified by the ethylene booster, and then returns to the ethylene tank car through the ethylene gaseous phase pipeline L7 to pressurize the tank car, the connection point, at which the outlet pipeline of the ethylene booster A1 is connected with the ethylene gaseous phase pipeline L7, leads to the low-temperature emission gas pipeline L6, the first safety valve SV1 is arranged on the low-temperature emission gas pipeline L6, and when the ethylene gaseous phase pipeline L7 is overpressure, the overpressure gas is discharged through the first safety valve SV1 of the low-temperature emission gas pipeline L6; The second refrigerant unloading liquid phase pipeline L17 is branched into two branch pipelines, i.e., the ethane unloading liquid phase pipeline L3 and the isopentane unloading liquid phase pipeline L5, the ethane unloading liquid phase pipeline L3 and the isopentane unloading liquid phase pipeline L5 are respectively connected with the liquid phase interface of the ethane storage tank and the isopentane storage tank, the ethane unloading liquid phase pipeline L3 is provided with the ethane unloading pump PB1, the ethane unloading pump return gas pipeline L20 is connected to the ethane gaseous phase return pipeline L2, and when the pump is operated, the gas in the ethane pump is discharged into the ethane gaseous phase return pipeline L2 through the pipeline by pressure detection, the isopentane unloading liquid phase pipeline L5 is provided with the isopentane unloading pump PB2, and after being opened, the isopentane is unloaded from the tank car to the isopentane storage tank, the isopentane unloading pump return gas pipeline L21 is connected to the isopentane gaseous phase return pipeline L4, and when the pump is operated, the gas in the isopentane unloading pump is discharged into the isopentane gaseous phase return pipeline L4 through the pipeline by pressure detection; One end of the refrigerant unloading arm purge return gas pipeline L1 is connected with the liquid phase and gaseous phase nitrogen interface of the refrigerant unloading arm ZXB1, and the other end of the refrigerant unloading arm purge return gas pipeline L1 is connected with the field station emission gas pipeline to the flare. The nitrogen gas inlet pipeline L14 is connected at one end to the nitrogen gas inlet pipeline of the site and at the other end to the liquid phase and gas phase nitrogen gas interface of the refrigerant unloading arm ZXB1. The nitrogen gas inlet pipeline L11 is connected at one end to the nitrogen gas inlet pipeline of the site and at the other end to the liquid phase and gas phase nitrogen gas interface of the refrigerant unloading arm ZXB2. The light hydrocarbon loading liquid phase pipeline L12 and the light hydrocarbon gas phase return pipeline L13 are respectively connected to the liquid phase interface and the gas phase interface of the light hydrocarbon loading arm ZXB2, and the other ends of the gas phase interface and the liquid phase interface of the light hydrocarbon loading arm are connected to the gas phase outlet and the liquid phase outlet of the light hydrocarbon storage tank, which is a light hydrocarbon recovery storage tank of the site, usually a C3+ hydrocarbon storage tank. The light hydrocarbon loading arm purge return pipeline L10 is connected at one end to the liquid phase and gas phase nitrogen gas interface of the light hydrocarbon unloading arm ZXB2 and at the other end to the site vent gas pipeline to the flare. The ethylene unloading liquid phase overpressure vent pipeline L22 is connected to the low-temperature vent gas pipeline L6 from the ethylene unloading liquid phase pipeline L8 (the connection is located downstream of the first safety valve, i.e., on the side away from the ethylene booster), and a second safety valve SV2 is provided on the ethylene unloading liquid phase overpressure vent pipeline L22.

[0042] Further, the normal-temperature vent gas pipeline L9 is branched from the light hydrocarbon loading liquid phase pipeline L12, and a third safety valve SV3 is provided on the normal-temperature vent gas pipeline L9.

[0043] The first temperature transmitter T1 is provided on the ethane gas phase return pipeline L2, and a first valve V1 and a second valve V2 are respectively provided on the two sides of the first temperature transmitter T1, and the first temperature transmitter T1, the first valve V1 and the second valve V2 are arranged on the side close to the refrigerant unloading arm ZXB1 at the connection between the ethane unloading pump return pipeline L20 and the ethane gas phase return pipeline L2.

[0044] The second temperature transmitter T2 is provided upstream of the ethane unloading pump PB1 on the ethane unloading liquid phase pipeline L3, and a third valve V3 and a fourth valve V4 are provided on the two sides of the second temperature transmitter T2, and the first pressure transmitter P1 is provided downstream of the ethane unloading pump PB1 on the ethane unloading liquid phase pipeline L3, and a first check valve ZH1 and a fifth valve V5 are provided on the two sides of the first pressure transmitter P1.

[0045] The third temperature transmitter T3 is provided on the isopentane gas phase return pipeline L4, and a seventh valve V7 and an eighth valve V8 are respectively provided on the two sides of the third temperature transmitter T3, and the eighth valve is located downstream of the connection point between the isopentane unloading pump return pipeline L21 and the isopentane gas phase return pipeline L4 (i.e., on the side away from the isopentane storage tank).

[0046] A fourth temperature transmitter T4 is arranged upstream of the isopentane unloading pump PB2 on the isopentane unloading liquid phase pipeline L5, a tenth valve V10 and an eleventh valve V11 are arranged on both sides of the fourth temperature transmitter T4, and a second pressure transmitter P2 is arranged downstream of the isopentane unloading pump PB2 on the isopentane unloading liquid phase pipeline L5, with a second check valve ZH2 and a twelfth valve V12 arranged on both sides of the second pressure transmitter P2.

[0047] A first pipeline filter G1 and a second pipeline filter G2 can be arranged upstream of the ethane unloading pump PB1 and the isopentane unloading pump PB2, respectively, on the ethane unloading liquid phase pipeline L3 between the fourth valve V4 and the ethane unloading pump PB1 and on the isopentane unloading liquid phase pipeline L5 between the eleventh valve V11 and the isopentane unloading pump PB2, to prevent impurities in the pipelines from entering the pump body and damaging the pump.

[0048] A third pressure transmitter P3 is arranged downstream of the outlet pipeline of the ethylene booster A1 and the connection point of the ethylene gas phase pipeline L7 (on the side away from the ethylene storage tank), with a thirteenth valve V13 and a third check valve ZH3 arranged on both sides of the third pressure transmitter, and a twenty-seventh valve V27 is arranged upstream of the outlet pipeline of the ethylene booster A1 and the connection point of the ethylene gas phase pipeline L7 (on the side close to the ethylene storage tank).

[0049] A fourteenth valve V14 is arranged on the ethylene booster liquid phase pipeline L19.

[0050] A sixteenth valve V16 and a fourth check valve ZH4 are arranged on the ethylene unloading liquid phase pipeline L8 (upstream of the position at which the ethylene unloading liquid phase overpressure relief pipeline L22 is branched off).

[0051] A seventeenth valve V17 is arranged on the hydrocarbon gas phase return pipeline L13.

[0052] An eighteenth valve V18, a fourth pressure transmitter P4, and a flow meter F1 are arranged in sequence on the light hydrocarbon loading liquid phase pipeline L12 in the flow direction.

[0053] A nineteenth valve V19 and a fifth check valve ZH5 are arranged in sequence on the nitrogen gas inlet pipeline L11.

[0054] A twenty-fifth valve V25 and a seventh check valve ZH7 are arranged in sequence on the refrigerant unloading arm nitrogen gas inlet pipeline L14.

[0055] The second twenty-fourth valve V24 and the second twenty-third valve V23 are arranged on the second refrigerant unloading liquid phase pipeline L17 in sequence. When unloading, the second twenty-fourth valve V24 is used for nitrogen replacement refrigerant unloading arm ZXB1 liquid phase arm and the first refrigerant unloading liquid phase pipeline L15 residual medium blowing and emptying, the second twenty-third valve V23 is closed at this time, and ethylene is prohibited to enter the ethane and isopentane pipeline.

[0056] The second twenty-sixth valve V26 and the eighth check valve ZH8 are arranged on the refrigerant unloading arm blowing and emptying gas pipeline L1; the twentieth valve V20 and the sixth check valve ZH6 are arranged on the light hydrocarbon loading arm blowing and emptying gas pipeline L10.

[0057] There are two sets of loading and unloading arms, one set is used for refrigerant unloading, and the other set is used for light hydrocarbon loading. The refrigerant unloading arm includes a liquid phase arm and a gas phase arm. One end of the liquid phase arm is connected with the ethane, isopentane and ethylene liquid inlet pipeline and the ethylene booster liquid phase pipeline (the other end of the liquid inlet pipeline is connected with the storage tank of the liquefied factory station), and the other end is connected with the tank truck liquid phase outlet. One end of the gas phase arm (BOG gas return arm) is connected with the tank truck BOG outlet, and the other end is connected with the BOG gas return pipeline (the ethane gas phase return pipeline L2, the isopentane gas phase return pipeline L4, the second refrigerant unloading gas phase pipeline L18 (further connected with L2 and L4), and the ethylene gas phase pipeline L7).

[0058] The ethylene unloading process includes the pipeline replacement process, the tank truck booster process and the ethylene unloading process.

[0059] Ethylene pipeline replacement process: unload arm connected ethane tank car gas phase and liquid phase, start ethylene unloading process. Open the second twenty-fifth valve V25 on the refrigerant unloading arm nitrogen inlet pipeline L14 and the twenty-fourth valve V24 on the second refrigerant unloading liquid pipeline L17, open the second twenty-fifth valve V25 to let nitrogen into the refrigerant unloading arm ZXB1, open the twenty-fourth valve V24 to let the other medium possibly remaining in the pipe be emptied, and detect the ethane and isopentane concentrations from the valve. During unloading, the twenty-fourth valve V24 is used for nitrogen replacement of the ZXB1 liquid phase arm and the first refrigerant unloading liquid pipeline L15 to blow off and empty the remaining medium, the twenty-third valve V23 on the second refrigerant unloading liquid pipeline L17 is closed at this time, and ethylene is prohibited from entering the ethane and isopentane pipeline. The first refrigerant unloading liquid pipeline L15 and the second refrigerant unloading liquid pipeline L17 are blown and replaced (the blowing gas comes from the gas station nitrogen pipeline, enters the refrigerant unloading arm ZXB1 liquid phase arm and the first refrigerant unloading liquid pipeline L15 through the refrigerant unloading arm nitrogen inlet pipeline L14, and the twenty-third valve V23 on the second refrigerant unloading liquid pipeline L17, the fourteenth valve V14 on the ethylene booster liquid pipeline L19, and the sixteenth valve V16 on the ethylene unloading liquid pipeline L8 are all in the closed state at this time. The twenty-fourth valve V24 is opened for discharge and replacement, and the concentration is detected at the same time. When the concentrations of ethane, isopentane, etc. are ≤0.1%, the twenty-fourth valve V24 and the twenty-fifth valve V25 are closed, the pipeline replacement is completed, and the tank car booster process is started.

[0060] Tanker pressurization process and ethylene unloading process: after the pipeline replacement process is completed, the thirteenth valve V13 on the ethylene gas phase pipeline L7 and the fourteenth valve V14 on the ethylene pressurization liquid phase pipeline L19 are automatically opened, ethylene enters the ethylene pressurizer, at this time, the liquid phase ethylene passes through the liquid phase arm through the first refrigerant unloading liquid phase pipeline L15 and the ethylene pressurization liquid phase pipeline L19 to enter the ethylene pressurizer to exchange heat with air and then gasify into gaseous ethylene, which returns to the tanker through the ethylene gas phase pipeline L7 and the refrigerant unloading arm ZXB1 gas phase arm to pressurize the tanker, at this time, the twenty-seventh valve V27 on the ethylene gas phase pipeline L7 is in a closed state, and the tanker pressurization process is started, when it is detected that the third pressure transmitter P3 pipeline pressure of the ethylene gas phase pipeline L7 is ≥0.5 MPa, the sixteenth valve V16 on the ethylene unloading liquid phase pipeline L8 is automatically opened, the thirteenth valve V13 on the ethylene gas phase pipeline L7 and the fourteenth valve V14 on the ethylene pressurization liquid phase pipeline L19 remain in an open state, and ethylene enters the ethylene storage tank through the ethylene unloading liquid phase pipeline L8, at this time, pressurization and unloading are simultaneously performed, during the unloading process, when it is detected that the pipeline pressure P3 of the ethylene gas phase pipeline L7 is <0.3 MPa, the sixteenth valve V16 on the ethylene unloading liquid phase pipeline L8 is automatically closed to stop unloading, and pressurization of the tanker continues, when the third pressure transmitter P3 pressure is ≥0.5 MPa, the sixteenth valve V16 is automatically opened, and the process is repeated until the third pressure transmitter P3 pressure is <0.25 MPa, and the unloading process is completed.

[0061] In the pressurization process, when the first safety valve SV1 pressure on the low-temperature emission gas pipeline L6 is ≥1.0 MPa, the first safety valve SV1 is automatically opened to emit and protect the unloading device.

[0062] In the unloading process, when the second safety valve SV2 pressure on the ethylene unloading liquid phase overpressure emission pipeline L22 is ≥1.0 MPa, the second safety valve SV2 is automatically opened to emit and protect the unloading device.

[0063] Ethane unloading process: including pipeline replacement process and ethane unloading process.

[0064] Ethane pipeline replacement process: unload arm connected ethane tank car gas phase and liquid phase, start ethane unloading process. Open the second twenty-fifth valve V25 on the refrigerant unloading arm nitrogen inlet pipeline L14 and the second twenty-fourth valve V24 on the second refrigerant unloading liquid phase pipeline L17, and use nitrogen to purge and replace the first refrigerant unloading liquid phase pipeline L15 and the second refrigerant unloading liquid phase pipeline L17. Open the second twenty-fifth valve V25 to allow nitrogen to enter the refrigerant unloading arm ZXB1, and open the second twenty-fourth valve V24 to allow other media that may remain in the pipeline to be emptied. At the same time, detect the concentration of ethylene and isopentane from the valve. When the concentration of ethylene, isopentane, etc. is ≤0.1%, close the second twenty-fourth valve V24 and the second twenty-fifth valve V25, and the pipeline replacement is complete. During the replacement process, if the temperature of any one of the first to fourth temperature transmitters T1 to T4 on the ethane gas phase return gas pipeline L2, the ethane unloading liquid phase pipeline L3, the isopentane gas phase return gas pipeline L4, and the isopentane unloading liquid phase pipeline L5 is ≤-10℃, the unloading program automatically stops. When the temperature in the pipeline is ≤-10℃ during operation, it indicates that the first valve V1, the third valve V3, the seventh valve V7, and the tenth valve V10 have internal leakage. To protect the ethane gas phase return gas pipeline L2, the ethane unloading liquid phase pipeline L3, the isopentane gas phase return gas pipeline L4, and the isopentane unloading liquid phase pipeline L5 normal temperature pipeline and the equipment on the pipeline, the device process is automatically stopped. After checking that the equipment is not faulty, the process can be restarted. After no fault, the concentration of ethylene and isopentane is ≤0.1%, and the temperature of any one of T1 to T4 is >-10℃, start the ethane unloading process.

[0065] Ethane unloading process: after the displacement is completed, the ethane unloading process is automatically started, the twenty-third valve V23 on the second refrigeration unloading liquid phase pipeline L17, the first valve V1, the second valve V2 on the ethane gas phase return pipeline L2, the third valve V3, the fourth valve V4, the fifth valve V5 on the ethane unloading liquid phase pipeline L3 are opened for a few seconds, for example, 5 seconds, and then the ethane unloading pump PB1 is automatically started (after the ethane unloading pump PB1 is started, the ethane is pressurized by the ethane unloading pump PB1 and then enters the ethane storage tank through the ethane unloading liquid phase pipeline L3, the ethane unloading pump return pipeline L20 is the return pipeline of the ethane unloading pump PB1, and when the pump is running, the gas in the pump is discharged into the ethane gas phase return pipeline L2 through the pipeline by pressure detection), and the ethane unloading liquid phase pipeline L3 starts to unload the ethane into the ethane storage tank. When the first pressure sensor P1 on the ethane unloading liquid phase pipeline L3 detects that the pressure is ≥7 barg, the sixth valve V6 on the ethane unloading pump return pipeline L20 is opened (the ethane enters the ethane gas phase return pipeline L2 to discharge the gas in the pump); when the first pressure sensor P1 detects that the pressure is <5 barg, the sixth valve V6 is closed. When the first pressure sensor P1 detects that the pressure is <3 barg, the unloading is completed, the ethane unloading pump PB1 is closed, and the sixth valve V6 is opened (the sixth valve V6 is opened to relieve the load, which facilitates the next pump start in the empty state. If the sixth valve V6 is closed, the next pump start will detect the pressure and cannot be started), and after a few minutes, for example, 5 minutes, all valves except the fifth valve V5 (the fifth valve V5 is a normally open valve) on the ethane unloading liquid phase pipeline L3 are closed, and the ethane unloading is completed.

[0066] The isopentane unloading process is the same as the ethane unloading process.

[0067] Isopentane unloading process: including pipeline displacement process and ethane-isopentane unloading process.

[0068] Isopentane pipeline replacement process: the unloading arm is connected with the ethane tank car gas phase and liquid phase, and the isopentane unloading process is started. The twenty-fifth valve V25 on the refrigerant unloading arm nitrogen inlet pipeline L14 and the twenty-fourth valve V24 on the second refrigerant unloading liquid phase pipeline L17 are opened, and the first refrigerant unloading liquid phase pipeline L15 and the second refrigerant unloading liquid phase pipeline L17 are purged and replaced with nitrogen. When the concentration of ethylene, ethane, etc. is ≤0.1%, the twenty-fourth valve V24 and the twenty-fifth valve V25 are closed, and the pipeline replacement is completed. During the replacement process, if any one of the first to fourth temperature transmitters T1 to T4 is ≤-10℃, the unloading program is automatically stopped (when the pipeline temperature is ≤-10℃ during operation, it indicates that the first valve V1, the third valve V3, the seventh valve V7, and the tenth valve V10 have internal leakage, and the ethane gas phase return pipeline L2, the ethane unloading liquid phase pipeline L3, the isopentane gas phase return pipeline L4, and the isopentane unloading liquid phase pipeline L5 normal temperature pipeline and the pipeline equipment are protected. The process is automatically stopped, and after checking that the equipment is not faulty, the process can be restarted), if any one of T1 to T4 is >-10℃, the isopentane unloading process is started.

[0069] Isopentane unloading process: after the displacement is completed, the isopentane unloading process is automatically started, the twenty-third valve V23 on the second refrigeration refrigerant unloading liquid phase pipeline L17, the seventh valve V7 and the eighth valve V8 on the isopentane gas phase return gas pipeline L4, the tenth valve V10, the eleventh valve V11 and the twelfth valve V12 on the isopentane unloading liquid phase pipeline L5 are opened for a few seconds, for example, 5 seconds, and then the isopentane unloading pump PB2 is automatically started (after the isopentane unloading pump PB2 is started, isopentane is unloaded from the tank truck to the isopentane storage tank. The pump is installed on the isopentane unloading liquid phase pipeline L5, and the isopentane unloading pump return gas pipeline L21 is connected with the isopentane gas phase return gas pipeline L4. During unloading, the second pressure sensor P2 of the isopentane unloading liquid phase pipeline L5 is detected to be normal, the ninth valve V9 on the isopentane unloading pump return gas pipeline L21 is automatically closed, the tenth valve, the eleventh valve and the twelfth valve V10\V11\V12 are automatically opened, and the isopentane unloading pump PB2 starts to pressurize to transport isopentane to the isopentane storage tank through the isopentane unloading liquid phase pipeline L5), and the isopentane unloading liquid phase pipeline L5 starts to unload isopentane to the isopentane storage tank. When the second pressure sensor P2 detects that the pressure is greater than or equal to 7 barg, the ninth valve V9 is opened (isopentane enters the isopentane gas phase return gas pipeline L4, and the gas in the pump is discharged); when the second pressure sensor P2 detects that the pressure is less than 5 barg, the ninth valve V9 is closed. When the second pressure sensor P2 detects that the pressure is less than 3 barg, the unloading is completed, the isopentane unloading pump PB2 is closed, and the ninth valve V9 is opened (in order to be unloaded, it is convenient to start the pump next time). After a few minutes, for example, 5 minutes, all the valves are closed except the twelfth valve V12 (the twelfth valve V12 is a normally open valve) of the isopentane unloading liquid phase pipeline L5, and the isopentane unloading is completed.

[0070] Light hydrocarbon loading process: including pipeline displacement process and light hydrocarbon loading process.

[0071] Light hydrocarbon pipeline displacement process: the loading arm is connected with the light hydrocarbon tank truck gas phase and liquid phase, and the light hydrocarbon loading process is started. The nineteenth valve V19 on the nitrogen inlet pipeline L11 and the twentieth valve V20 on the light hydrocarbon loading arm purge return gas pipeline L10 are opened, nitrogen enters the light hydrocarbon loading arm gas phase arm and liquid phase arm through the nitrogen inlet pipeline L11, the nineteenth valve V19 and the twentieth valve V20 are automatically closed after ten seconds, for example, 15 seconds, and the displacement is completed.

[0072] The light hydrocarbon loading process: after the displacement is finished, the eighteenth valve V18 on the light hydrocarbon loading liquid phase pipeline L12 is automatically opened, the light hydrocarbon starts to be metered through the flowmeter F1, when the loading flow reaches the set value, the eighteenth valve V18 is automatically closed, after the light hydrocarbon pipeline displacement process is repeated, the loading is finished. In the loading process, when the third safety valve SV3 on the normal temperature blow-off gas pipeline L9 is greater than or equal to 1.4 MPa, the third safety valve SV3 is automatically opened to blow off, and the loading device is protected. In the light hydrocarbon loading process, the hydrocarbon gas phase return gas pipeline L13 is a return gas pipeline, when the tank car is connected with the device, the seventeenth valve V17 on the hydrocarbon gas phase return gas pipeline L13 is automatically opened to release the tank car BOG gas, so that the pressure of the tank car is reduced, and the light hydrocarbon liquid phase is ensured to enter the tank car.

[0073] The preferred embodiments of the present application are described above, however, the above description is not used for the purpose of limitation. Those skilled in the art can make many changes or modifications to the present application without departing from the spirit and scope of the present application. The changes or modifications should be included in the scope of the appended claims.

Claims

1. A multifunctional refrigerant unloading and light hydrocarbon loading device, characterized in that, It includes a refrigerant unloading boom (ZXB1), a light hydrocarbon loading boom (ZXB2), an ethylene booster (A1), an ethane unloading pump (PB1), and an isopentane unloading pump (PB2). The tank truck's vapor phase interface is connected to the vapor phase inlet of the refrigerant unloading arm (ZXB1). The vapor phase outlet of the refrigerant unloading arm (ZXB1) is connected to the first refrigerant unloading vapor phase pipeline (L16). The first refrigerant unloading vapor phase pipeline (L16) branches into two branch pipes: the second refrigerant unloading vapor phase pipeline (L18) and the ethylene vapor phase pipeline (L7). The second refrigerant unloading vapor phase pipeline (L18) branches into the ethane vapor phase return pipeline (L2) and the isopentane vapor phase return pipeline (L4). The other end of the ethane vapor phase return pipeline (L2) is connected to the vapor phase interface of the ethane storage tank. The other end of the isopentane vapor phase return pipeline (L4) is connected to the vapor phase interface of the isopentane storage tank. The other end of the ethylene vapor phase pipeline (L7) is connected to the vapor phase interface of the ethylene storage tank. The tank truck's liquid phase interface connects to the liquid phase inlet of the refrigerant unloading arm (ZXB1), and the liquid phase outlet of the refrigerant unloading arm (ZXB1) connects to the first refrigerant unloading liquid phase pipeline (L15). The first refrigerant unloading liquid phase pipeline (L15) branches into three branches: the second refrigerant unloading liquid phase pipeline (L17), the ethylene unloading liquid phase pipeline (L8), and the ethylene booster liquid phase pipeline (L19). One end of the ethylene booster liquid phase pipeline (L19) is connected to the first refrigerant unloading liquid phase pipeline (L15), and the other end is connected to the ethylene booster (A1). The outlet pipe of the ethylene booster (A1) is connected to the ethylene gas phase pipeline (L7). After the liquid ethylene is vaporized by the ethylene booster, it returns to the ethylene tank truck through the ethylene gas phase pipeline (L7) to pressurize the tank truck. The connection point between the outlet pipe of the ethylene booster (A1) and the ethylene gas phase pipeline (L7) leads to a cryogenic vent gas pipeline (L6). A first safety valve (SV1) is installed on the cryogenic vent gas pipeline (L6). When the ethylene gas phase pipeline (L7) is overpressurized, the overpressurized gas is released through the first safety valve of the cryogenic vent gas pipeline (L6). The second refrigeration unloading liquid phase pipeline (L17) branches into two lines: the ethane unloading liquid phase pipeline (L3) and the isopentane unloading liquid phase pipeline (L5). The ethane unloading liquid phase pipeline (L3), the isopentane unloading liquid phase pipeline (L5), and the ethylene unloading liquid phase pipeline (L8) are respectively connected to the liquid phase interfaces of the ethane storage tank, the isopentane storage tank, and the ethylene storage tank. The ethane unloading liquid phase pipeline (L3) is equipped with an ethane unloading pump (PB1), and the ethane unloading pump return gas pipeline (L20) is connected to the ethane gas phase return gas pipeline. Line (L2) is used to release gas from the ethane pump into the ethane gas phase return line (L2) through pressure detection when the pump is running. The isopentane unloading liquid phase line (L5) is equipped with an isopentane unloading pump (PB2), which unloads isopentane from the tanker to the isopentane storage tank after being opened. The isopentane unloading pump return line (L21) is connected to the isopentane gas phase return line (L4). When the pump is running, the gas from the isopentane unloading pump is released into the isopentane gas phase return line (L4) through pressure detection. One end of the refrigerant unloading arm purge return gas line (L1) is connected to the liquid phase and gas phase nitrogen interface of the refrigerant unloading arm (ZXB1), and the other end is connected to the station vent gas line to the flare. One end of the nitrogen inlet line (L14) of the refrigerant unloading arm is connected to the nitrogen inlet line of the station, and the other end is connected to the liquid phase and gas phase nitrogen interface of the refrigerant unloading arm (ZXB1). One end of the nitrogen inlet pipeline (L11) is connected to the nitrogen inlet pipeline of the station, and the other end is connected to the liquid and gas nitrogen interfaces of the refrigerant unloading arm (ZXB2). The light hydrocarbon loading liquid phase pipeline (L12) and the light hydrocarbon gas phase return pipeline (L13) are respectively connected to the liquid phase interface and gas phase interface of the light hydrocarbon loading arm (ZXB2). The other end of the gas phase interface and liquid phase interface of the light hydrocarbon loading arm are connected to the gas phase outlet and liquid phase outlet of the light hydrocarbon storage tank. The light hydrocarbon storage tank is a light hydrocarbon recovery storage tank for the station. One end of the light hydrocarbon loading arm purge return gas pipeline (L10) is connected to the liquid phase and gas phase nitrogen interface of the light hydrocarbon unloading arm (ZXB2), and the other end is connected to the station vent gas pipeline to the flare. An ethylene unloading liquid phase overpressure venting line (L22) is led out from the ethylene unloading liquid phase line (L8) and connected to the cryogenic venting line (L6). A second safety valve (SV2) is installed on the ethylene unloading liquid phase overpressure venting line (L22).

2. The multifunctional refrigerant unloading and light hydrocarbon loading device according to claim 1, characterized in that, A normal temperature venting gas line (L9) is led out from the light hydrocarbon loading liquid phase line (L12), and a third safety valve (SV3) is installed on the normal temperature venting gas line (L9).

3. The multifunctional refrigerant unloading and light hydrocarbon loading device according to claim 1 or 2, characterized in that, A first temperature transmitter (T1) is installed on the ethane gas phase return pipeline (L2), and a first valve (V1) and a second valve (V2) are respectively installed on both sides of the first temperature transmitter (T1).

4. The multifunctional refrigerant unloading and light hydrocarbon loading device according to claim 3, characterized in that, A second temperature transmitter (T2) is installed upstream of the ethane unloading pump (PB1) on the ethane unloading liquid phase pipeline (L3). A third valve (V3) and a fourth valve (V4) are installed on both sides of the second temperature transmitter (T2). A first pressure transmitter (P1) is installed downstream of the ethane unloading pump (PB1) on the ethane unloading liquid phase pipeline (L3). A first check valve (ZH1) and a fifth valve (V5) are installed on both sides of the first pressure transmitter (P1).

5. The multifunctional refrigerant unloading and light hydrocarbon loading device according to claim 4, characterized in that, A third temperature transmitter (T3) is installed on the isopentane gas phase return line (L4). A seventh valve (V7) and an eighth valve (V8) are installed on both sides of the third temperature transmitter (T3). The eighth valve is located downstream of the connection point between the isopentane unloading pump return line (L21) and the isopentane gas phase return line (L4).

6. The multifunctional refrigerant unloading and light hydrocarbon loading device according to claim 5, characterized in that, A fourth temperature transmitter (T4) is installed upstream of the isopentane unloading pump (PB2) on the isopentane unloading liquid phase pipeline (L5). A tenth valve (V10) and an eleventh valve (V11) are installed on both sides of the fourth temperature transmitter (T4). A second pressure transmitter (P2) is installed downstream of the isopentane unloading pump (PB2) on the isopentane unloading liquid phase pipeline (L5). A second check valve (ZH2) and a twelfth valve (V12) are installed on both sides of the second pressure transmitter (P2).

7. The multifunctional refrigerant unloading and light hydrocarbon loading device according to claim 6, characterized in that, A third pressure transmitter (P3) is installed downstream of the connection point between the outlet pipe of the ethylene booster (A1) and the ethylene gas phase pipeline (L7). A thirteenth valve (V13) and a third check valve (ZH3) are installed on both sides of the third pressure transmitter. A twenty-seventh valve (V27) is installed upstream of the connection point between the outlet pipe of the ethylene booster (A1) and the ethylene gas phase pipeline (L7). The fourteenth valve (V14) is installed on the ethylene pressurized liquid phase pipeline (L19). The ethylene unloading liquid phase pipeline (L8) is equipped with a sixteenth valve (V16) and a fourth check valve (ZH4). The seventeenth valve (V17) is installed on the hydrocarbon gas phase return line (L13); Along the flow direction, the light hydrocarbon loading liquid phase pipeline (L12) is equipped with the eighteenth valve (V18), the fourth pressure transmitter (P4), and the flow meter (F1). The nitrogen inlet line (L11) is equipped with the nineteenth valve (V19) and the fifth check valve (ZH5) in sequence. The nitrogen inlet line (L14) of the refrigerant unloading arm is equipped with the twenty-fifth valve (V25) and the seventh check valve (ZH7) in sequence. The refrigerant unloading arm purge return line (L1) is equipped with the twenty-sixth valve (V26) and the eighth check valve (ZH8); the light hydrocarbon loading arm purge return line (L10) is equipped with the twentieth valve (V20) and the sixth check valve (ZH6).

8. The multifunctional refrigerant unloading and light hydrocarbon loading device according to claim 7, characterized in that, The second refrigerant unloading liquid phase pipeline (L17) is equipped with the twenty-fourth valve (V24) and the twenty-third valve (V23) in sequence. During unloading, the twenty-fourth valve (V24) is used to purge and vent the residual medium in the liquid phase arm of the refrigerant unloading arm (ZXB1) and the first refrigerant unloading liquid phase pipeline (L15) with nitrogen. At this time, the twenty-third valve (V23) is closed to prevent ethylene from entering the ethane and isopentane pipelines.

9. A multifunctional refrigerant unloading and light hydrocarbon loading process, the method using the multifunctional refrigerant unloading and light hydrocarbon loading device according to any one of claims 1-8, comprising the following steps: Ethylene unloading process: including pipeline replacement process, tanker pressurization process, and ethylene unloading process; Ethylene pipeline purging process: The unloading arm connects to the gas and liquid phases of the ethane tanker. The ethylene unloading process is initiated. The 25th valve (V25) on the nitrogen inlet line (L14) of the refrigerant unloading arm and the 24th valve (V24) on the second refrigerant unloading liquid phase line (L17) are opened. The 25th valve (V25) is opened to allow nitrogen to enter the refrigerant unloading arm (ZXB1). The 24th valve (V24) is opened to purge any remaining media in the pipes. The first refrigerant unloading liquid phase line (L15) and the second refrigerant unloading liquid phase line (L17) are purged and replaced. The purging gas comes from the nitrogen line at the gas station and passes through the refrigerant unloading arm. Nitrogen inlet line (L14) enters the liquid phase arm of refrigerant unloading arm (ZXB1) and line L15. At this time, the twenty-third valve (V23) on the second refrigerant unloading liquid phase line (L17), the fourteenth valve (V14) on the ethylene pressurization liquid phase line (L19), and the sixteenth valve (V16) on the ethylene unloading liquid phase line (L8) are all closed. The twenty-fourth valve (V24) is opened for emission replacement, and the concentration is detected at the same time. When the concentration of ethane and isopentane is ≤0.1%, the twenty-fourth valve (V24) and the twenty-fifth valve (V25) are closed. The pipeline replacement is completed, and the tank truck pressurization process is started. Tanker pressurization process and ethylene unloading process: After the pipeline replacement process is completed, the thirteenth valve (V13) on the ethylene gas phase pipeline (L7) and the fourteenth valve (V14) on the ethylene pressurization liquid phase pipeline (L19) are automatically opened, allowing ethylene to enter the ethylene pressurizer. At this time, the liquid ethylene passes through the liquid phase arm, the first refrigerant unloading liquid phase pipeline (L15), and the ethylene pressurization liquid phase pipeline (L19) into the ethylene pressurizer, where it exchanges heat with the air and vaporizes into gaseous ethylene. This gaseous ethylene then returns to the tanker via the ethylene gas phase pipeline (L7) and the refrigerant unloading arm (ZXB1), pressurizing the tanker. At this time, the twenty-seventh valve (V27) on the ethylene gas phase pipeline (L7) is closed, initiating the tanker pressurization process. When the pressure of the third pressure transmitter (P3) on the ethylene gas phase pipeline (L7) is detected to be ≥0.5MPa, the ethylene unloading begins. The sixteenth valve (V16) on the ethylene liquid phase pipeline (L8) automatically opens, while the thirteenth valve (V13) on the ethylene gas phase pipeline (L7) and the fourteenth valve (V14) on the ethylene pressurization liquid phase pipeline (L19) remain open. Ethylene enters the ethylene storage tank through the ethylene unloading liquid phase pipeline (L8). At this time, pressurization and unloading occur simultaneously. During the unloading process, when the pressure of the third pressure transmitter (P3) on the ethylene gas phase pipeline (L7) is detected to be <0.3MPa, the sixteenth valve (V16) on the ethylene unloading liquid phase pipeline (L8) is automatically closed, unloading stops, and pressurization of the tanker continues. When the pressure of the third pressure transmitter (P3) is ≥0.5MPa, the sixteenth valve (V16) automatically opens. This process is repeated until the pressure of the third pressure transmitter (P3) is <0.25MPa, at which point unloading ends. Ethane unloading process: including pipeline replacement process and ethane unloading process Ethane pipeline purging procedure: Connect the unloading arm to the gas and liquid phases of the ethane tanker. Start the ethane unloading process. Open the 25th valve (V25) on the nitrogen inlet line (L14) of the refrigerant unloading arm and the 24th valve (V24) on the liquid phase line (L17) of the second refrigerant unloading arm. Purge and replace the first liquid phase line (L15) and the second liquid phase line (L17) of the refrigerant unloading arm with nitrogen. Open the 25th valve (V25) to allow nitrogen to enter the refrigerant unloading arm (ZXB1). Open the 24th valve (V24) to purge any other media that may remain in the pipes. When the concentration of ethylene and isopentane is ≤0.1%, close the 24th valve (V24) and the 25th valve (V25). The pipeline purging is now complete. Ethane unloading process: After the purging is completed, the ethane unloading process will automatically begin. A few seconds after the opening of the 23rd valve (V23) on the second refrigeration unloading liquid phase pipeline (L17), the first valve (V1), the second valve (V2) on the ethane gas phase return pipeline (L2), and the third valve (V3), fourth valve (V4), and fifth valve (V5) on the ethane unloading liquid phase pipeline (L3), the ethane unloading pump (PB1) will automatically open. Ethane, after being pressurized by the ethane unloading pump (PB1), will enter the ethane storage tank through the ethane unloading liquid phase pipeline (L3). The ethane unloading pump return pipeline (L20) is the return pipeline for the ethane unloading pump (PB1). When the pump is running, pressure detection will release the gas inside the ethane pump through this pipeline into the ethane gas phase return pipeline (L2). Ethane unloading begins on the ethane unloading liquid phase pipeline (L3), transferring ethane to the ethane storage tank. When the first pressure sensor (P1) on the ethane unloading liquid phase pipeline (L3) detects a pressure ≥7 barg, the sixth valve (V6) on the ethane unloading pump return gas pipeline (L20) opens, allowing ethane to enter the ethane gas phase return gas pipeline (L2) and releasing gas from the pump. When the first pressure sensor (P1) detects a pressure <5 barg, the sixth valve (V6) closes. When the first pressure sensor (P1) detects a pressure <3 barg, unloading ends, the ethane unloading pump (PB1) closes, and the sixth valve (V6) opens. Several minutes later, all valves except the fifth valve (V5) on the ethane unloading liquid phase pipeline (L3) close, and ethane unloading ends. Isopentane unloading process: including pipeline replacement process and ethylene isopentane unloading process. Isopentane pipeline purging procedure: Connect the unloading arm to the gas and liquid phases of the ethane tanker. Start the isopening process. Open the 25th valve (V25) on the nitrogen inlet line (L14) of the refrigerant unloading arm and the 24th valve (V24) on the liquid phase line (L17) of the second refrigerant unloading arm. Purge and purge the first liquid phase line (L15) and the second liquid phase line (L17) of the refrigerant unloading arm with nitrogen. When the concentration of ethylene and ethane is ≤0.1%, close the 24th valve (V24) and the 25th valve (V25). The pipeline purging is now complete. Isopentane unloading process: After the replacement is completed, the isopening process is automatically initiated. A few seconds after the opening of the twenty-third valve (V23) on the second refrigeration unloading liquid phase line (L17), the seventh valve (V7) and eighth valve (V8) on the isopening gas phase return line (L4), and the tenth valve (V10), eleventh valve (V11), and twelfth valve (V12) on the isopening liquid phase line (L5), the isopening pump (PB2) automatically starts, initiating the isopening process and unloading the isopening into the isopening storage tank. When the second pressure sensor (P2) detects a pressure ≥7 barg, The ninth valve (V9) opens, and isopentane enters the isopentane gas phase return line (L4), releasing the gas in the pump. When the second pressure sensor P2 on the isopentane unloading liquid phase line (L5) detects a pressure < 5 barg, the ninth valve (V9) on the isopentane unloading pump return line L21 closes. When the second pressure sensor (P2) detects a pressure < 3 barg, unloading ends, the isopentane unloading pump (PB2) closes, and the ninth valve (V9) opens. After a few minutes, all valves except the twelfth valve (V12) on the isopentane unloading liquid phase line (L5) close, and the isopentane unloading ends. Light hydrocarbon loading process: including pipeline replacement process and light hydrocarbon loading process Light hydrocarbon pipeline replacement process: The loading arm connects to the gas phase and liquid phase of the light hydrocarbon tanker. The light hydrocarbon loading process is started. The nineteenth valve (V19) on the nitrogen inlet line (L11) and the twentieth valve (V20) on the light hydrocarbon loading arm purge return line (L10) are opened. Nitrogen enters the gas phase arm and liquid phase arm of the light hydrocarbon loading arm through the nitrogen inlet line (L11). After a few seconds, the nineteenth valve (V19) and the twentieth valve (V20) automatically close, and the replacement is completed. Light hydrocarbon loading process: After the replacement is completed, the eighteenth valve (V18) on the light hydrocarbon loading liquid phase pipeline (L12) will open automatically, and the light hydrocarbon will start to be measured through the flow meter (F1). When the loading flow reaches the set value, the eighteenth valve (V18) will close automatically. After the light hydrocarbon pipeline replacement process is repeated, the loading is completed.

10. The multifunctional refrigerant unloading and light hydrocarbon loading process according to claim 9, characterized in that, In the pressurization process of ethylene unloading, when the pressure of the first safety valve (SV1) on the cryogenic venting pipeline (L6) is ≥1.0MPa, the first safety valve (SV1) automatically opens to vent and protect the unloading device; during the unloading process, when the pressure of the second safety valve (SV2) on the ethylene unloading liquid phase overpressure venting pipeline (L22) is ≥1.0MPa, the second safety valve (SV2) automatically opens to vent and protect the unloading device; and / or During the light hydrocarbon loading process, when the pressure of the third safety valve (SV3) on the ambient temperature venting gas pipeline (L9) is ≥1.4MPa, the third safety valve (SV3) will automatically open to vent and protect the loading device. During the loading of light hydrocarbons, the hydrocarbon gas phase return line (L13) is a return line. When the tank truck is connected to this device, the seventeenth valve (V17) on the hydrocarbon gas phase return line (L13) is automatically opened to release the BOG gas from the tank truck, reduce the pressure of the tank truck, and ensure that the liquid phase light hydrocarbons enter the tank truck.

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