Multifunctional refrigerant unloading and light hydrocarbon loading device

Abstract

The utility model relates to a multifunctional refrigerant unloading and light hydrocarbon loading device which 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 multifunctional refrigerant unloading and light hydrocarbon loading process and the multifunctional refrigerant unloading and light hydrocarbon loading device are developed according to the field environment and the use condition of a liquefaction factory, and are 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] This utility model relates to a multifunctional refrigerant (ethane, isopentane, and ethylene) unloading and light hydrocarbon loading device suitable for LNG liquefaction plants, which can realize the functions of automatic unloading of refrigerants (ethane, isopentane, and ethylene) and loading of light hydrocarbons. Background Technology

[0002] Currently, most LNG liquefaction terminals employ the MRC (Medium-Refrigerant Combination) liquefaction process, which is simple, energy-efficient, and widely used in LNG liquefaction. MRC typically uses methane, ethane, isopentane, ethylene, and nitrogen. Methane and nitrogen are usually obtained at the terminal, while ethane, isopentane, and ethylene require separate tank truck transport to the LNG liquefaction terminal for unloading. Conventional refrigerant unloading requires different unloading arms depending on the medium temperature. Furthermore, since natural gas typically contains light hydrocarbons (C3 and above), these need to be removed during the liquefaction process. The removed light hydrocarbons can be recovered, improving the utilization value of natural gas; therefore, a separate light hydrocarbon recovery and loading unit is needed to transport them to other utilization scenarios via tank truck. Utility Model Content

[0003] To solve the above-mentioned problems in the prior art, this utility model provides a multi-functional refrigerant unloading and light hydrocarbon loading device, which includes a refrigerant unloading arm, a light hydrocarbon loading arm, an ethylene booster, an ethane unloading pump, and an isopentane unloading pump.

[0004] The tank truck's vapor phase interface is connected to the vapor phase inlet of the refrigerant unloading arm, and the vapor phase outlet of the refrigerant unloading arm is connected to the first refrigerant unloading vapor phase pipeline. The first refrigerant unloading vapor phase pipeline branches into two branch pipes, namely the second refrigerant unloading vapor phase pipeline and the ethylene vapor phase pipeline. The second refrigerant unloading vapor phase pipeline branches into an ethane vapor phase return pipeline and an isopentane vapor phase return pipeline. The other end of the ethane vapor phase return pipeline is connected to the vapor phase interface of the ethane storage tank, the other end of the isopentane vapor phase return pipeline is connected to the vapor phase interface of the isopentane storage tank, and the other end of the ethylene vapor phase pipeline is connected to the vapor phase interface of the ethylene storage tank.

[0005] The tank truck's liquid phase interface connects to the liquid phase inlet of the refrigerant unloading arm, and the liquid phase outlet of the refrigerant unloading arm connects to the first refrigerant unloading liquid phase pipeline. The first refrigerant unloading liquid phase pipeline branches into three branches: 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 connects to the first refrigerant unloading liquid phase pipeline, and the other end connects to the ethylene booster (this pipeline branches off from the loading / unloading arm's liquid phase branch; ethylene exits from the loading / unloading arm's liquid phase arm and enters...). (The ethylene booster pressurizes the tank truck after vaporization.) The outlet pipe of the ethylene booster is connected to the ethylene gas phase pipeline. After the liquid ethylene is vaporized by the ethylene booster, it returns to the ethylene tank truck through the ethylene gas phase pipeline to pressurize the tank truck. A low-temperature vent gas pipeline is led out from the connection point between the outlet pipe of the ethylene booster and the ethylene gas phase pipeline. A first safety valve is installed on the low-temperature vent gas pipeline. When the ethylene gas phase pipeline is overpressurized, the overpressurized gas is released through the first safety valve of the low-temperature vent gas pipeline.

[0006] The second refrigeration unloading liquid phase pipeline branches into two lines: an ethane unloading liquid phase pipeline and an isopentane unloading liquid phase pipeline. These pipelines connect to the liquid phase interfaces of the ethane, isopentane, and ethylene storage tanks, respectively. An ethane unloading pump is installed on the ethane unloading liquid phase pipeline. The ethane unloading pump return pipeline (leading from the return port of the ethane unloading pump) connects to the ethane gas phase return pipeline. When the pump operates... During operation, pressure detection is used to release the gas inside the ethane pump into the ethane gas phase return pipeline through this pipeline. The isopentane unloading liquid phase pipeline is equipped with an isopentane unloading pump. After being turned on, isopentane is unloaded from the tank truck into the isopentane storage tank. The isopentane unloading pump return pipeline (leading out from the isopentane unloading pump return port) is connected to the isopentane gas phase return pipeline. When the pump is running, pressure detection is used to release the gas inside the isopentane unloading pump into the isopentane gas phase return pipeline through this pipeline.

[0007] One end of the refrigerant unloading boom purge return gas line is connected to the liquid phase and gas phase nitrogen interface of the refrigerant unloading boom, and the other end is connected to the station vent gas line to the flare.

[0008] One end of the nitrogen inlet pipeline of the refrigerant unloading arm is connected to the nitrogen inlet pipeline of the station, and the other end is connected to the liquid phase and gas phase nitrogen interface of the refrigerant unloading arm.

[0009] One end of the nitrogen inlet pipeline is connected to the nitrogen supply pipeline of the station, and the other end is connected to the liquid and gas phase nitrogen interfaces of the light hydrocarbon loading arm.

[0010] The light hydrocarbon loading liquid phase pipeline and the light hydrocarbon gas phase return pipeline are respectively connected to the liquid phase interface and gas phase interface of the light hydrocarbon loading arm. 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 at the station, which is usually a C3+ hydrocarbon storage tank.

[0011] One end of the light hydrocarbon loading arm purge return gas pipeline is connected to the liquid phase and gas phase nitrogen interface of the light hydrocarbon loading arm, and the other end is connected to the station vent gas pipeline to the flare.

[0012] An ethylene unloading liquid phase overpressure venting pipeline is led out from the ethylene unloading liquid phase pipeline and connected to the cryogenic venting gas pipeline (the connection point is located downstream of the first safety valve, i.e., on the side away from the ethylene booster). A second safety valve is installed on the ethylene unloading liquid phase overpressure venting pipeline.

[0013] Furthermore, a normal temperature venting gas pipeline is led out from the liquid phase pipeline of the light hydrocarbon loading, and a third safety valve is installed on the normal temperature venting gas pipeline.

[0014] Preferably, a first temperature transmitter is provided on the ethane gas phase return pipeline, and a first valve and a second valve are respectively provided on both sides of the first temperature transmitter.

[0015] Preferably, a second temperature transmitter is installed upstream of the ethane unloading pump on the ethane unloading liquid phase pipeline, and a third valve and a fourth valve are installed on both sides of the second temperature transmitter. A first pressure transmitter is installed downstream of the ethane unloading pump on the ethane unloading liquid phase pipeline, and a first check valve and a fifth valve are installed on both sides of the first pressure transmitter.

[0016] Preferably, a third temperature transmitter is installed on the isopentane gas phase return pipeline, and a seventh valve and an eighth valve are installed on both sides of the third temperature transmitter, respectively. The eighth valve is located downstream of the connection point between the isopentane unloading pump return pipeline and the isopentane gas phase return pipeline (i.e., on the side away from the isopentane storage tank).

[0017] Preferably, a fourth temperature transmitter is installed upstream of the isopentane unloading pump on the isopentane unloading liquid phase pipeline, and a tenth valve and an eleventh valve are installed on both sides of the fourth temperature transmitter. A second pressure transmitter is installed downstream of the isopentane unloading pump on the isopentane unloading liquid phase pipeline, and a second check valve and a twelfth valve are installed on both sides of the second pressure transmitter.

[0018] Preferably, the 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 equipped with a first pipeline filter and a second pipeline filter, respectively, for the ethane unloading pump and the isopentane unloading pump, so as to prevent impurities in the pipeline from entering the pump body and damaging the pump.

[0019] Preferably, a third pressure transmitter is installed on the ethylene gas phase pipeline downstream of the connection point between the outlet pipe of the ethylene booster and the ethylene gas phase pipeline (on the side away from the ethylene storage tank). A thirteenth valve and a third check valve are respectively installed on both sides of the third pressure transmitter. A twenty-seventh valve is installed upstream of the connection point between the outlet pipe of the ethylene booster and the ethylene gas phase pipeline.

[0020] Preferably, a fourteenth valve is provided on the ethylene pressurization liquid phase pipeline.

[0021] Preferably, a sixteenth valve and a fourth check valve are provided on the ethylene unloading liquid phase pipeline (upstream of the ethylene unloading liquid phase overpressure venting pipeline).

[0022] Preferably, a seventeenth valve is provided on the light hydrocarbon gas phase return pipeline.

[0023] Preferably, the liquid phase pipeline for loading light hydrocarbons is provided with an eighteenth valve, a fourth pressure transmitter, and a flow meter in sequence along the flow direction.

[0024] Preferably, the nitrogen inlet pipeline is equipped with a nineteenth valve and a fifth check valve in sequence.

[0025] Preferably, the nitrogen inlet pipeline of the refrigerant unloading arm is equipped with a 25th valve and a 7th check valve in sequence.

[0026] Preferably, the second refrigerant unloading liquid phase pipeline is equipped with a twenty-fourth valve and a twenty-third valve in sequence. During unloading, the twenty-fourth valve is used to purge and vent residual media in the refrigerant unloading arm liquid phase arm and the first refrigerant unloading liquid phase pipeline with nitrogen. At this time, the twenty-third valve is closed to prevent ethylene from entering the ethane and isopentane pipelines.

[0027] Preferably, the refrigerant unloading arm purge return line is equipped with a 26th valve and an 8th check valve; the light hydrocarbon loading arm purge return line is equipped with a 20th valve and a 6th check valve.

[0028] There are two sets of loading arms: one for refrigerant unloading and one for light hydrocarbon loading. The refrigerant unloading arm consists of a liquid phase arm and a gas phase arm. One end of the liquid phase arm is connected to the ethane, isopentane, and ethylene inlet lines and the ethylene pressurization liquid phase line (the other end of the inlet lines connects to the storage tanks at the liquefaction plant), and the other end is connected to the tank truck's liquid phase outlet. The gas phase arm (BOG return arm) is connected to the tank truck's BOG outlet at one end and to the BOG return lines (ethane gas phase return line, isopentane gas phase return line, second refrigerant unloading gas phase line (further connected to the ethane and isopentane gas phase return lines), and ethylene gas phase line) at the other end.

[0029] This utility model further provides a multifunctional refrigerant unloading and light hydrocarbon loading process using the above-mentioned device, including:

[0030] Ethylene unloading process: including pipeline replacement process, tanker pressurization process and ethylene unloading process.

[0031] Ethylene pipeline purging procedure: The unloading arm connects to the gas and liquid phases of the ethane tanker. To initiate the ethylene unloading process, open valve 25 on the nitrogen inlet line of the refrigerant unloading arm and valve 24 on the liquid phase line of the second refrigerant unloading arm. Opening valve 25 allows nitrogen to enter the refrigerant unloading arm. Opening valve 24 allows any remaining media in the pipeline to be purged. Simultaneously, ethane and isopentane concentrations are monitored at this valve. During unloading, valve 24 is used to purge residual media in the liquid phase arm and liquid phase pipeline with nitrogen. With the system in operation, valve 23 on the second refrigerant unloading liquid phase pipeline is closed to prevent ethylene from entering the ethane and isopentane pipelines. The first and second refrigerant unloading liquid phase pipelines are then purged and replaced (the purging gas comes from the gas station's nitrogen pipeline, enters the refrigerant unloading arm's liquid phase arm and the first refrigerant unloading liquid phase pipeline through the refrigerant unloading arm's nitrogen inlet pipeline; at this time, valves 23, 14, and 16 are all closed; valve 24 is opened for purging and replacement, while simultaneously monitoring the concentration). When the concentrations of ethane and isopentane are detected to be ≤0.1%, valves 24 and 25 are closed, the pipeline replacement is complete, and the tanker pressurization process is initiated.

[0032] Tanker pressurization and ethylene unloading processes: 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, allowing ethylene to enter the ethylene pressurizer. At this time, the liquid ethylene enters the ethylene pressurizer through the liquid phase arm, the first refrigerant unloading liquid phase pipeline, and the ethylene pressurization liquid phase pipeline, where it exchanges heat with air and vaporizes into gaseous ethylene. This gaseous ethylene then returns to the tanker via the ethylene gas phase pipeline and the refrigerant unloading arm, pressurizing the tanker. Meanwhile, the twenty-seventh valve on the ethylene gas phase pipeline is closed, initiating the tanker pressurization process. When the pressure detected by the third pressure transmitter on the ethylene gas phase pipeline is ≥0.5 MPa... The sixteenth valve on the ethylene unloading liquid phase pipeline automatically opens, while the thirteenth valve on the ethylene gas phase pipeline and the fourteenth valve on the ethylene pressurization liquid phase pipeline remain open. Ethylene enters the ethylene storage tank through the ethylene unloading liquid phase pipeline. At this time, pressurization and unloading occur simultaneously. During the unloading process, when the pressure detected by the third pressure transmitter of the ethylene gas phase pipeline is <0.3MPa, the sixteenth valve on the ethylene unloading liquid phase pipeline automatically closes, stopping the unloading and continuing to pressurize the tanker. When the pressure of the third pressure transmitter is ≥0.5MPa, the sixteenth valve automatically opens. This process repeats until the pressure of the third pressure transmitter is <0.25MPa, at which point the unloading ends.

[0033] During the pressurization process, when the pressure of the first safety valve on the low-temperature venting pipeline is ≥1.0MPa, the first safety valve will automatically open to vent and protect the unloading device.

[0034] During the unloading process, when the pressure of the second safety valve on the ethylene unloading liquid phase overpressure venting pipeline is ≥1.0MPa, the second safety valve will automatically open to vent and protect the unloading device.

[0035] Ethane unloading process: includes pipeline replacement process and ethane unloading process.

[0036] Ethane pipeline purging procedure: Connect the unloading arm to the ethane tanker's gas and liquid phases, and start the ethane unloading process. Open valve 25 on the nitrogen inlet line of the refrigerant unloading arm and valve 24 on the liquid phase line of the second refrigerant unloading line. Purge and purge the first and second liquid phase lines of the refrigerant unloading line with nitrogen. Open valve 25 to allow nitrogen to enter the refrigerant unloading arm. Open valve 24 to purge any other media that may remain in the lines. Simultaneously, monitor the concentrations of ethylene and isopentane at this valve. When the concentrations of ethylene, isopentane, etc., are ≤0.1%, close valves 24 and 25, and the pipeline purging is complete. During the purging process, if any of the temperatures on the first to fourth temperature transmitters on the ethane gas return line, ethane unloading liquid phase line, isopentane gas return line, or isopentane unloading liquid phase line are ≤-10℃, the unloading procedure will automatically stop. When the internal pipe temperature is ≤-10℃ during operation, it indicates internal leakage in valves 1, 3, 7, and 10. To protect the ethane gas return pipeline, ethane unloading liquid phase pipeline, isopentane gas return pipeline, isopentane unloading liquid phase pipeline, and other ambient temperature pipelines and equipment, the process will automatically stop. The process can only be restarted after the equipment is checked and found to be fault-free. After the fault is cleared, if the ethylene and isopentane concentrations are ≤0.1% and any one of the first to fourth temperature transmitters has a temperature >-10℃, the ethane unloading process will be restarted.

[0037] Ethane unloading process: After the replacement is completed, the ethane unloading process will automatically start. The 23rd valve on the second refrigeration unloading liquid phase pipeline, the first and second valves on the ethane gas phase return pipeline, and the third, fourth, and fifth valves on the ethane unloading liquid phase pipeline will open for a few seconds, for example, 5 seconds. After the ethane unloading pump starts, the ethane will be pressurized by the ethane unloading pump and enter the ethane storage tank through the ethane unloading liquid phase pipeline. The ethane unloading pump return pipeline is the ethane unloading pump return gas pipeline. When the pump is running, the gas in the ethane pump will be released into the ethane gas phase return pipeline through this pipeline by pressure detection. The ethane unloading liquid phase pipeline will start unloading ethane and unload it into the ethane storage tank. When the first pressure sensor on the ethane unloading liquid phase pipeline detects a pressure ≥7 barg, the sixth valve on the ethane unloading pump return gas pipeline opens (ethane enters the ethane gas phase return gas pipeline, releasing gas from the pump); when the first pressure sensor detects a pressure <5 barg, the sixth valve closes. When the first pressure sensor detects a pressure <3 barg, unloading ends, the ethane unloading pump shuts down, and the sixth valve opens (opening the sixth valve is to release the load, facilitating a no-load start for the next pump startup. If the sixth valve is closed, the pump will detect pressure and fail to start next time). After several minutes, for example, 5 minutes, all valves except the fifth valve on the ethane unloading liquid phase pipeline (the fifth valve is a normally open valve) close, and ethane unloading ends.

[0038] The unloading process for isopentane is the same as that for ethane.

[0039] Isopentane unloading process: including pipeline replacement process and ethylene isopentane unloading process.

[0040] Isopentane pipeline purging procedure: Connect the unloading arm to the gas and liquid phases of the ethane tanker, and initiate the isopentane unloading process. Open valve 25 on the nitrogen inlet line of the refrigerant unloading arm and valve 24 on the liquid phase line of the second refrigerant unloading arm. Purge and purge the first and second refrigerant unloading liquid phase lines with nitrogen. When the concentration of ethylene, ethane, etc., is ≤0.1%, close valves 24 and 25, and the pipeline purging is complete. During the replacement process, if any of the first to fourth temperature transmitters has a temperature ≤ -10℃, the unloading procedure will automatically stop (when the pipe temperature is ≤ -10℃ during operation, it indicates that there is internal leakage in valves 1, 3, 7, and 10. To protect the ethane gas phase return pipeline, ethane unloading liquid phase pipeline, isopentane gas phase return pipeline, isopentane unloading liquid phase pipeline, and other ambient temperature pipelines and equipment on the pipelines, the process will automatically stop. The process can only be restarted after checking that the equipment is fault-free). If any of the first to fourth temperature transmitters has a temperature > -10℃, the isopentane unloading process will be started.

[0041] Isopentane unloading process: After the replacement is completed, the isopening process automatically begins. The 23rd valve on the second refrigeration unloading liquid phase pipeline, the 7th and 8th valves on the isopening gas phase return pipeline, and the 10th, 11th, and 12th valves on the isopening liquid phase pipeline open for several seconds (e.g., 5 seconds). After the isopening pump starts, it automatically unloads the isopening pump from the tanker truck into the isopening storage tank. This pump is installed on the isopening liquid phase pipeline. The isopentane unloading pump return gas line is connected to the isopentane gas phase return gas line. During unloading, if the pressure of the second pressure sensor on the isopentane unloading liquid phase line is normal, the ninth valve on the isopentane unloading pump return gas line will automatically close, while the tenth, eleventh, and twelfth valves will automatically open. The isopentane unloading pump will begin pressurizing, transporting isopentane through the isopentane unloading liquid phase line to the isopentane storage tank. The isopentane unloading liquid phase line will then begin unloading isopentane into the isopentane storage tank. When the second pressure sensor detects a pressure ≥7 barg, the ninth valve will open (isopentane enters the isopentane gas phase return gas line, releasing gas from the pump); when the second pressure sensor detects a pressure <5 barg, the ninth valve will close. When the second pressure sensor detects a pressure < 3 barg, unloading is complete, the isopentane unloading pump is shut down, and the ninth valve is opened (to release the load and facilitate no-load startup of the pump next time). After a few minutes, for example 5 minutes, all valves except the twelfth valve of the isopentane unloading liquid phase pipeline (the twelfth valve is a normally open valve) are closed, and isopentane unloading is complete.

[0042] Light hydrocarbon loading process: including pipeline replacement process and light hydrocarbon loading process.

[0043] Light hydrocarbon pipeline replacement process: Connect the loading arm to the gas and liquid phases of the light hydrocarbon tanker and start the light hydrocarbon loading process. Open the nineteenth valve on the nitrogen inlet line and the twentieth valve on the light hydrocarbon loading arm purging return line. Nitrogen enters the gas and liquid phase arms of the light hydrocarbon loading arm through the nitrogen inlet line. After about 15 seconds, the nineteenth and twentieth valves automatically close, and the replacement is complete.

[0044] Light hydrocarbon loading process: After the purging is completed, the eighteenth valve on the light hydrocarbon loading liquid phase pipeline automatically opens, and light hydrocarbons begin to be metered through the flow meter. When the loading flow reaches the set value, the eighteenth valve automatically closes. After repeating the light hydrocarbon pipeline purging process, the loading is complete. During the loading process, when the pressure of the third safety valve on the ambient temperature vent gas pipeline is ≥1.4MPa, the third safety valve automatically opens to release gas and protect the loading device. During the light hydrocarbon loading process, the light hydrocarbon gas phase return gas pipeline is the return gas pipeline. When the tank truck is connected to this device, the seventeenth valve on the light hydrocarbon gas phase return gas pipeline automatically opens to release BOG gas from the tank truck, reducing the tank truck pressure and ensuring that liquid phase light hydrocarbons enter the tank truck.

[0045] Advantages of this utility model:

[0046] (1) A single unloading arm is used to complete the unloading functions of ethane, isopentane, and ethylene. Automatic switching is achieved through process pipeline connections and valve control. Nitrogen purging is performed before each unloading to ensure that there are no other media in the pipeline, ensuring the purity and safety of the refrigerant, and avoiding the freezing of pipelines due to residual ethane and isopentane during ethylene unloading;

[0047] (2) The integrated design of isopentane unloading and light hydrocarbon loading is designed with two loading arms on the left and right sides, sharing a loading and unloading island, which reduces the footprint by three-quarters;

[0048] (3) The pressurization principle for refrigerant unloading is the same as that for LNG unloading, but the operating conditions are different. LNG unloading involves multiple tank trucks unloading continuously, requiring rapid pressurization. Therefore, a separate pressurization arm is needed to ensure that pressurization and unloading occur simultaneously. Ethylene unloading is usually the initial unloading of ethylene before the station's use or a subsequent replenishment of ethylene. The required quantity is small, and the unloading time is not critical. To reduce equipment investment, this invention designs a single arm and pipeline for pressurization and unloading. During pressurization, ethylene enters both the pressurization pipeline and the unloading pipeline simultaneously through the liquid phase arm pipeline. Through pressure detection, when the pressure is below 0.3 barg, only the pressurization pipeline valve is opened, and the unloading pipeline valve is closed. When the pressure increases to 0.5 barg, the unloading pipeline valve is opened again to begin the ethylene unloading process. During operation, when the pressure drops below 0.3 barg again, close the unloading pipeline valve, start pressurizing to 0.5 barg, and then open the unloading pipeline valve again. Repeat this process until unloading is completed. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the multifunctional refrigerant unloading and light hydrocarbon recovery device of this utility model.

[0050] Figure label:

[0051] L1: Refrigerant unloading arm purging return line; L2: Ethane gas phase return line; L3: Ethane unloading liquid phase line; L4: Isopentane gas phase return line; L5: Isopentane unloading liquid phase line; L6: Cryogenic vent line; L7: Ethylene gas phase line; L8: Ethylene unloading liquid phase line; L9: Ambient temperature vent line; L10: Light hydrocarbon loading arm purging return line; L11: Nitrogen inlet line; L12: Light hydrocarbon loading liquid phase line; L13: Light hydrocarbon gas phase return line; L14: Nitrogen inlet line for refrigerant unloading arm; 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 during ethane unloading); L21: Isopentane unloading return gas line (pump gas phase recovery during isopentane unloading); L22: Ethylene unloading liquid phase overpressure venting line;

[0052] 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;

[0053] G1: First pipeline filter; G2: Second pipeline filter;

[0054] P1~P3: First to third pressure transmitters; T1~T4: First to fourth temperature transmitters. Detailed Implementation

[0055] This invention provides a device and process for unloading refrigerants (ethane, isopentane, and ethylene) and loading light hydrocarbons in LNG liquefaction plants. The device features automatic process control and adjustment to meet the needs of refrigerant unloading and light hydrocarbon loading at LNG plant terminals. During tank truck unloading and loading, automatic shut-off valves automatically switch between various process pipelines to initiate the unloading or loading process.

[0056] According to the first embodiment of the present invention, the present invention provides a multi-functional refrigerant unloading and light hydrocarbon loading device, which includes a refrigerant unloading arm ZXB1, a light hydrocarbon loading arm ZXB2, an ethylene booster A1, an ethane unloading pump PB1, and an isopentane unloading pump PB2.

[0057] 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.

[0058] The tank truck's liquid phase interface is connected to the liquid phase inlet of the refrigerant unloading arm ZXB1. The liquid phase outlet of the refrigerant unloading arm ZXB1 is connected 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. (This pipeline branches off from the loading / unloading arm's liquid phase branch; ethylene exits from the loading / unloading arm's liquid phase arm and enters the ethylene booster gas.) (After vaporization, the ethylene is pressurized to pressurize the tank truck). The outlet pipe of the ethylene booster A1 is connected to the ethylene gas phase pipeline L7. The ethylene gas phase pipeline L7 is further connected to the ethylene tank truck. 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 the low-temperature vent gas pipeline L6. The low-temperature vent gas pipeline L6 is equipped with a first safety valve SV1. When the ethylene gas phase pipeline L7 is overpressurized, the overpressurized gas is released through the first safety valve SV1 of the low-temperature vent gas pipeline L6.

[0059] The second refrigeration unloading liquid phase pipeline L17 branches into two lines: ethane unloading liquid phase pipeline L3 and isopentane unloading liquid phase pipeline L5. Ethane unloading liquid phase pipeline L3, isopentane unloading liquid phase pipeline L5, and ethylene unloading liquid phase pipeline L8 are connected to the liquid phase interfaces of the ethane storage tank, isopentane storage tank, and ethylene storage tank, respectively. 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 L... 2. When the pump is running, the gas inside the ethane pump is released through this pipeline into the ethane gas phase return pipeline L2 by pressure detection. The isopentane unloading liquid phase pipeline L5 is equipped with an isopentane unloading pump PB2. After opening, isopentane is unloaded from the tank truck to the isopentane storage tank. The isopentane unloading pump return pipeline L21 is connected to the isopentane gas phase return pipeline L4. When the pump is running, the gas inside the isopentane unloading pump is released through this pipeline into the isopentane gas phase return pipeline L4 by pressure detection.

[0060] 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.

[0061] One end of the nitrogen inlet pipeline L14 of the refrigerant unloading arm is connected to the nitrogen inlet pipeline of the station, and the other end is connected to the liquid and gas phase nitrogen interface of the refrigerant unloading arm ZXB1.

[0062] 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 phase nitrogen interface of the light hydrocarbon loading arm ZXB2.

[0063] 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 at the station, which is usually a C3+ hydrocarbon storage tank.

[0064] 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 loading arm ZXB2, and the other end is connected to the station vent gas pipeline to the flare.

[0065] An ethylene unloading liquid phase overpressure venting pipeline L22 is led out from the ethylene unloading liquid phase pipeline L8 and connected to the cryogenic venting gas pipeline L6 (the connection is located downstream of the first safety valve, i.e., on the side away from the ethylene booster). A second safety valve SV2 is installed on the ethylene unloading liquid phase overpressure venting pipeline L22.

[0066] Furthermore, a normal temperature venting gas pipeline L9 is led out from the light hydrocarbon loading liquid phase pipeline L12, and a third safety valve SV3 is installed on the normal temperature venting gas pipeline L9.

[0067] A first temperature transmitter T1 is installed on the ethane gas phase return line L2. A first valve V1 and a second valve V2 are respectively installed on both sides of the first temperature transmitter T1. The first temperature transmitter T1, the first valve V1 and the second valve V2 are located on the side near the refrigerant unloading arm ZXB1 at the connection between the ethane unloading pump return line L20 and the ethane gas phase return line L2.

[0068] 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.

[0069] 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 (i.e., on the side away from the isopentane storage tank).

[0070] 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.

[0071] The upstream pipelines of ethane unloading pump PB1 and isopentane unloading pump PB2 (i.e., the ethane unloading liquid phase pipeline L3 between the fourth valve V4 and ethane unloading pump PB1, and the isopentane unloading liquid phase pipeline L5 between the eleventh valve V11 and isopentane unloading pump PB2) can be equipped with a first pipeline filter G1 and a second pipeline filter G2 respectively, for PB1 and PB2, to prevent impurities in the pipeline from entering the pump body and damaging the pump.

[0072] A third pressure transmitter P3 is installed on the ethylene gas phase pipeline L7 downstream of the connection point between the outlet pipe of the ethylene booster A1 and the ethylene gas phase pipeline L7 (on the side away from the ethylene storage tank). A thirteenth valve V13 and a third check valve ZH3 are respectively installed on both sides of the third pressure transmitter. A twenty-seventh valve V27 is installed on the ethylene gas phase pipeline L7 upstream of the connection point between the outlet pipe of the ethylene booster A1 and the ethylene gas phase pipeline L7 (on the side closer to the ethylene storage tank).

[0073] The fourteenth valve, V14, is installed on the ethylene pressurization liquid phase pipeline L19.

[0074] The sixteenth valve V16 and the fourth check valve ZH4 are installed on the ethylene unloading liquid phase pipeline L8 (upstream of the ethylene unloading liquid phase overpressure venting pipeline L22).

[0075] The seventeenth valve, V17, is installed on the light hydrocarbon gas phase return pipeline L13.

[0076] Along the flow direction, the liquid phase pipeline L12 for loading light hydrocarbons is equipped with the eighteenth valve V18, the fourth pressure transmitter P4, and the flow meter F1.

[0077] The nitrogen inlet pipeline L11 is equipped with the nineteenth valve V19 and the fifth check valve ZH5 in sequence.

[0078] The nitrogen inlet line L14 of the refrigerant unloading arm is equipped with the 25th valve V25 and the 7th check valve ZH7 in sequence.

[0079] 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 refrigerant unloading arm ZXB1 liquid phase arm 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.

[0080] The refrigerant unloading arm purge return line L1 is equipped with the 26th valve V26 and the 8th check valve ZH8; the light hydrocarbon loading arm purge return line L10 is equipped with the 20th valve V20 and the 6th check valve ZH6.

[0081] There are two sets of loading arms: one for refrigerant unloading and one for light hydrocarbon loading. The refrigerant unloading arm consists of a liquid phase arm and a gas phase arm. One end of the liquid phase arm is connected to the ethane, isopentane, and ethylene inlet lines and the ethylene pressurization liquid phase line (the other end of the inlet lines connects to the storage tanks at the liquefaction plant), and the other end is connected to the tank truck's liquid phase outlet. The gas phase arm (BOG return arm) is connected to the tank truck's BOG outlet at one end and to the BOG return lines (ethane gas phase return line L2, isopentane gas phase return line L4, second refrigerant unloading gas phase line L18 (further connected to L2 and L4), and ethylene gas phase line L7).

[0082] Ethylene unloading process: including pipeline replacement process, tanker pressurization process and ethylene unloading process.

[0083] Ethylene pipeline purging procedure: Connect the unloading arm to the ethane tanker's gas and liquid phases, and initiate the ethylene 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 second refrigerant unloading liquid phase line L17. Open the 25th valve V25 to allow nitrogen to enter the refrigerant unloading arm ZXB1. Open the 24th valve V24 to purge any remaining media in the pipeline. Simultaneously, monitor the ethane and isopentane concentrations at this valve. During unloading, the 24th valve V24 is used for nitrogen purging of residual media in the ZXB1 liquid phase arm and the first refrigerant unloading liquid phase line L15. The 23rd valve V23 on the second refrigerant unloading liquid phase line L17 is closed at this time to prevent ethylene from entering. The ethane and isopentane pipelines are purged, and the first refrigerant unloading liquid phase pipeline L15 and the second refrigerant unloading liquid phase pipeline L17 are purged and replaced (the purging gas comes from the nitrogen pipeline at the gas field station, enters the refrigerant unloading arm ZXB1 liquid phase arm and the first refrigerant unloading liquid phase pipeline L15 through the nitrogen inlet pipeline L14). At this time, the twenty-third valve V23 on the second refrigerant unloading liquid phase pipeline L17, the fourteenth valve V14 on the ethylene booster liquid phase pipeline L19, and the sixteenth valve V16 on the ethylene unloading liquid phase pipeline L8 are all closed. The twenty-fourth valve V24 is opened for emission replacement, and the concentration is monitored simultaneously. 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 tanker pressurization process is started.

[0084] Tanker pressurization and ethylene unloading processes: 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 enters the ethylene pressurizer through the liquid phase arm, the first refrigerant unloading liquid phase pipeline L15, and the ethylene pressurization liquid phase pipeline L19, where it exchanges heat with 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 ≥0.5 MPa... At time a, the sixteenth valve V16 on the ethylene unloading 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 P3 of 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 tank truck continues. When the pressure P3 of the third pressure transmitter is ≥0.5MPa, the sixteenth valve V16 automatically opens. This process repeats until the pressure P3 of the third pressure transmitter is <0.25MPa, at which point unloading ends.

[0085] During the pressurization process, when the pressure of the first safety valve SV1 on the low-temperature venting gas pipeline L6 is ≥1.0MPa, the first safety valve SV1 will automatically open to release the gas and protect the unloading device.

[0086] 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 will automatically open to vent and protect the unloading device.

[0087] Ethane unloading process: includes pipeline replacement process and ethane unloading process.

[0088] Ethane pipeline purging procedure: Connect the unloading arm to the gas and liquid phases of the ethane tanker truck and initiate the ethane unloading process. Open valve 25 (V25) on the nitrogen inlet line L14 of the refrigerant unloading arm and valve 24 (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 second refrigerant unloading arm with nitrogen. Open valve 25 (V25) to allow nitrogen to enter the refrigerant unloading arm ZXB1. Open valve 24 (V24) to purge any remaining media in the pipeline. Simultaneously, monitor the concentrations of ethylene and isopentane at this valve. When the concentrations of ethylene, isopentane, etc., are ≤0.1%, close valves 24 (V24) and 25 (V25). The pipeline purging is complete. During the replacement process, if any of the temperatures on the first to fourth temperature transmitters T1 to T4 of the ethane gas phase return line L2, ethane unloading liquid phase line L3, isopentane gas phase return line L4, and isopentane unloading liquid phase line L5 are ≤-10℃, the unloading procedure will automatically stop. If the pipe temperature is ≤-10℃ during operation, it indicates internal leakage in valves V1, V3, V7, and V10. To protect the ethane gas phase return line L2, ethane unloading liquid phase line L3, isopentane gas phase return line L4, isopentane unloading liquid phase line L5, and the equipment on these lines, the process will automatically stop. The process can only be restarted after the equipment is checked and found to be fault-free. After the fault is cleared, if the ethylene and isopentane concentrations are ≤0.1% and any temperature on T1 to T4 is >-10℃, the ethane unloading process will be restarted.

[0089] Ethane unloading process: After the replacement is completed, the ethane unloading process will automatically start. The 23rd valve V23 on the second refrigeration unloading liquid phase pipeline L17, the first valve V1 and the second valve V2 on the ethane gas phase return pipeline L2, and the third valve V3, the fourth valve V4, and the fifth valve V5 on the ethane unloading liquid phase pipeline L3 will open for a few seconds, for example, 5 seconds. After the ethane unloading pump PB1 opens, ethane will be pressurized by the ethane unloading pump PB1 and 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, the gas in the ethane pump will be released into the ethane gas phase return pipeline L2 through this pipeline by pressure detection. The ethane unloading liquid phase pipeline L3 will start unloading ethane and unload it into 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 (ethane enters the ethane gas phase return gas pipeline L2, 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 (opening the sixth valve V6 is to release the load, facilitating no-load startup of the pump next time. If the sixth valve V6 is closed, the pump will detect pressure and cannot start next time). After several minutes, for example, 5 minutes, all valves except the fifth valve V5 on the ethane unloading liquid phase pipeline L3 (the fifth valve V5 is a normally open valve) close, and ethane unloading ends.

[0090] The unloading process for isopentane is the same as that for ethane.

[0091] Isopentane unloading process: including pipeline replacement process and ethylene isopentane unloading process.

[0092] Isopentane pipeline purging procedure: Connect the unloading arm to the gas and liquid phases of the ethane tanker, and initiate the isopentane unloading process. Open valve 25 (V25) on the nitrogen inlet line L14 of the refrigerant unloading arm and valve 24 (V24) on the liquid phase line L17 of the second refrigerant unloading arm. Purge and purge the liquid phase lines L15 and L17 of the first refrigerant unloading arm with nitrogen. When the concentration of ethylene, ethane, etc., is ≤0.1%, close valves 24 (V24) and 25 (V25). The pipeline purging is now complete. During the replacement process, if any of the four temperature transmitters T1 to T4 has a temperature ≤ -10℃, the unloading procedure will automatically stop. (When the pipe temperature is ≤ -10℃ during operation, it indicates that there is internal leakage in valves V1, V3, V7, and V10. To protect the ethane gas phase return pipeline L2, the ethane unloading liquid phase pipeline L3, the isopentane gas phase return pipeline L4, the isopentane unloading liquid phase pipeline L5, and the equipment on the pipelines, the process will automatically stop. The process can only be restarted after the equipment is checked and found to be fault-free.) If any of the four temperature transmitters T1 to T4 has a temperature > -10℃, the isopentane unloading process will be started.

[0093] Isopentane unloading process: After the replacement is completed, the isopening process automatically begins. The 23rd valve V23 on the second refrigeration unloading liquid phase pipeline L17, the 7th valve V7 and 8th valve V8 on the isopening gas phase return pipeline L4, and the 10th valve V10, 11th valve V11, and 12th valve V12 on the isopening liquid phase pipeline L5 automatically open after a few seconds, for example, 5 seconds. (After the isopening of the isopening isopening pump PB2, isopening ... The isopentane unloading pump return gas line L21 is connected to the isopentane gas phase return gas line L4. During unloading, if the pressure of the second pressure sensor P2 on the isopentane unloading liquid phase line L5 is normal, the ninth valve V9 on the isopentane unloading pump return gas line L21 will automatically close, and the tenth, eleventh, and twelfth valves V10, V11, and V12 will automatically open. The isopentane unloading pump PB2 will begin pressurization, transporting isopentane through the isopentane unloading liquid phase line L5 to the isopentane storage tank. The isopentane unloading liquid phase line L5 will begin unloading isopentane into the isopentane storage tank. When the second pressure sensor P2 detects a pressure ≥7 barg, the ninth valve V9 will open (isopentane enters the isopentane gas phase return gas line L4, releasing gas from the pump); when the second pressure sensor P2 detects a pressure <5 barg, the ninth valve V9 will close. When the second pressure sensor P2 detects a pressure < 3 barg, unloading is complete, isopentane unloading pump PB2 is shut off, and the ninth valve V9 is opened (to relieve the load and facilitate no-load start-up of the pump next time). After a few minutes, for example 5 minutes, all valves except the twelfth valve V12 of the isopentane unloading liquid phase pipeline L5 (the twelfth valve V12 is a normally open valve) are closed, and isopentane unloading is complete.

[0094] Light hydrocarbon loading process: including pipeline replacement process and light hydrocarbon loading process.

[0095] Light hydrocarbon pipeline replacement process: Connect the loading arm to the gas and liquid phases of the light hydrocarbon tanker and start the light hydrocarbon loading process. Open 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. Nitrogen enters the gas and liquid phase arms of the light hydrocarbon loading arm through the nitrogen inlet line L11. After about 15 seconds, valves V19 and V20 will automatically close, and the replacement is complete.

[0096] Light hydrocarbon loading process: After the purging is completed, valve V18 on the light hydrocarbon loading liquid phase pipeline L12 automatically opens, and light hydrocarbons begin to be metered through flow meter F1. When the loading flow reaches the set value, valve V18 automatically closes. After repeating the light hydrocarbon pipeline purging process, the loading is complete. During the loading process, when the pressure of the third safety valve SV3 on the ambient temperature vent gas pipeline L9 is ≥1.4MPa, the third safety valve SV3 automatically opens to release gas and protect the loading device. During the light hydrocarbon loading process, the light hydrocarbon gas phase return pipeline L13 is the return gas pipeline. When the tank truck is connected to this device, valve V17 on the light hydrocarbon gas phase return pipeline L13 automatically opens to release BOG gas from the tank truck, reducing the tank truck pressure and ensuring that liquid phase light hydrocarbons enter the tank truck.

[0097] The preferred embodiments of this utility model have been described above; however, the above description is not intended to be limiting. Those skilled in the art can make many changes or modifications to this utility model without departing from its spirit and scope. Such changes or modifications should be included within 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 phase nitrogen interfaces of the light hydrocarbon loading 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 line (L10) is connected to the liquid phase and gas phase nitrogen interface of the light hydrocarbon loading arm (ZXB2), and the other end is connected to the station vent gas line 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 light hydrocarbon gas phase return line (L13) is equipped with the seventeenth valve (V17); 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.

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