A gas station unloading system and a control method thereof

Abstract

The application discloses a gas station unloading system and a control method thereof. The gas station unloading system comprises a multi-stage compression cylinder, a fixed-displacement hydraulic drive system, a gas storage device, a gas dispenser, an electric control valve group, a gas pressure detection unit and a control module. The hydraulic drive system, the gas dispenser, the electric control valve group and the gas pressure detection unit are respectively in communication connection with the control module. The gas storage device comprises a plurality of gas storage cylinders with different target gas storage pressures. The electric control valve group comprises a second electric control valve arranged on each gas storage pipeline and a fourth electric control valve arranged on at least one oil port of the last-stage compression cylinder. During unloading, the control module can control the second electric control valve on each gas storage pipeline to work according to a preset gas filling control strategy, and control the opening and closing state of the fourth electric control valve according to the intake pressure of the second-to-last-stage compression cylinder and the real-time gas storage pressure of the currently filled gas storage cylinder. The application can effectively improve the unloading rate and unloading efficiency of the gas station unloading system.

Description

Technical Field

[0001] This application relates to the field of gas station unloading control technology, and in particular to a gas station unloading system and its control method. Background Technology

[0002] Gas stations (such as hydrogen refueling stations and CNG (compressed natural gas) refueling stations) are important infrastructure for the application of gaseous fuels in the transportation sector. The high-pressure gas supply equipment outside the gas station usually uses long-tube trailers.

[0003] When a long-tube trailer unloads gas at a gas station, the gas in the trailer is compressed and pressurized by the gas compression system within the station before being transported to the gas storage unit for storage. During the unloading process, the gas pressure inside the storage tank of the long-tube trailer continuously decreases. The storage pressure of existing gas storage units is generally fixed, and the compression ratio of the same compression system is also fixed. When the gas pressure in the long-tube trailer drops to a certain level, the compressed gas produced by the compression system is lower than the pressure inside the storage unit, making further refilling impossible. At this point, unloading of gas from the long-tube trailer can no longer continue.

[0004] When the gas pressure in the storage unit reaches a certain value and cannot be further increased, there are usually two ways to handle it: one is for the long-tube trailer to leave the gas station to continue loading gas. In this case, the unloading rate of the long-tube trailer is low, resulting in a waste of transportation resources. The other way is for the long-tube trailer to stay at the gas station and wait for the gas storage unit to use the gas dispenser to refuel external gas-using equipment (such as gas-fueled vehicles) to reduce the gas pressure in the storage unit to a lower value. Then, the gas pressure in the long-tube trailer is compressed again by the compression system to refuel the gas storage unit, thereby increasing the unloading rate of the long-tube trailer. However, this will significantly increase the parking time of the long-tube trailer and occupy a lot of space, which will also result in a waste of transportation and space resources.

[0005] In addition, the compression system of a gas station generally uses a multi-stage compression cylinder. Because the hydraulic drive system of a variable displacement compression system is more expensive, gas stations usually use a fixed displacement compression system, whose output hydraulic oil displacement is fixed per unit time. Therefore, when all the compression cylinders of the multi-stage compression cylinder work simultaneously, the reversing frequency is fixed, and the compressed exhaust volume per unit time is fixed. In the initial stage of unloading gas from a long-tube trailer, the gas pressure in its storage tank is relatively high, resulting in a high intake pressure for the multi-stage compression system. The compression pressure of the first-stage compressor before the final-stage compressor usually reaches the charging pressure of the storage device. However, in existing gas station unloading systems, all the compressors in the multi-stage compression system are constantly working during unloading. Therefore, in the initial stage of unloading, because the compression pressure of the first-stage compressor before the final-stage compressor usually reaches the charging pressure of the storage device, the final-stage compressor does not actually compress the gas. In other words, the final-stage compressor does no work; instead, its piston reciprocating motion consumes energy transmitted by hydraulic oil by overcoming friction between the piston and the cylinder. This increases useless energy loss in the hydraulic drive system, reduces the working efficiency of each stage of compressor before the final-stage compressor, and thus reduces the overall compression efficiency of the compression system, consequently reducing the unloading efficiency of the unloading system.

[0006] Therefore, how to improve the unloading rate and efficiency of the gas station unloading system is an urgent problem to be solved in this field. Summary of the Invention

[0007] To address the aforementioned technical problems, this application provides a gas station unloading system and its control method, which can effectively improve the unloading rate and efficiency of the gas station unloading system.

[0008] The first objective of this application is to provide a gas unloading system for a gas station.

[0009] The aforementioned objective of this application is achieved through the following technical solution:

[0010] A gas unloading system for a gas station includes a multi-stage compression cylinder, a fixed-displacement hydraulic drive system, a gas storage device, a gas dispenser, an electrically controlled valve assembly, a gas pressure detection unit, and a control module. The hydraulic drive system, the gas dispenser, the electrically controlled valve assembly, and the gas pressure detection unit are all communicatively connected to the control module.

[0011] The gas storage device includes multiple gas storage cylinders with different target gas storage pressures.

[0012] The multi-stage compression cylinder includes multiple compression cylinders connected in series from the first stage to the last stage via an air supply pipeline. The air inlet of the first stage compression cylinder is connected to the long tube trailer via an air inlet pipeline, and the air outlet of the last stage compression cylinder is connected to the air inlet of the air outlet pipeline.

[0013] The inlet of each of the plurality of gas storage cylinders is connected to the outlet of the outlet pipeline through its respective gas storage pipeline, and the outlet of each of the plurality of gas storage cylinders is connected to the inlet of the gas dispenser through its respective gas filling pipeline.

[0014] The hydraulic drive system is connected to the inlet / outlet and outlet / inlet of each compression cylinder in the multi-stage compression cylinder via hydraulic pipelines.

[0015] The electronically controlled valve group includes a first electronically controlled valve disposed at one end of the air inlet of the air inlet pipeline, a second electronically controlled valve disposed on each air storage pipeline, a third electronically controlled valve disposed on each air filling pipeline, and a fourth electronically controlled valve disposed on at least one oil port of the final stage compression cylinder.

[0016] The air pressure detection unit includes an air inlet for detecting the inlet pressure P of the penultimate compression cylinder. 进 The intake pressure sensor is installed on each gas cylinder to detect the real-time gas pressure P of each gas cylinder. 瓶 The gas storage pressure sensor;

[0017] The control module is configured to control the second electrically controlled valves on each gas storage pipeline according to a preset inflation control strategy, so as to sequentially fill each gas cylinder of the gas storage device in descending order of the target gas storage pressure, and according to the inlet pressure P of the penultimate compression cylinder. 进 and the real-time gas pressure P of the currently filled gas cylinder 瓶 This controls the opening and closing state of the fourth electrically controlled valve, so that the final stage compression cylinder can be engaged or disengaged from compression operation.

[0018] Preferably, the step is based on the intake pressure P of the penultimate stage compression cylinder. 进 and the real-time gas pressure P of the currently filled gas cylinder 瓶 Controlling the opening and closing state of the fourth electrically controlled valve includes:

[0019] Determine the intake pressure P 进 and real-time gas storage pressure P 瓶 Does the preset valve opening condition meet?

[0020] If the conditions are met, the first control command is output to control the fourth electronically controlled valve to open, connect the oil circuit of the final stage compression cylinder, and enable the final stage compression cylinder to engage in compression work.

[0021] If the conditions are not met, a second control command is output to close the fourth electrically controlled valve, disconnecting the oil circuit of the final stage compression cylinder and causing the final stage compression cylinder to cease compression operation.

[0022] The preset valve opening conditions are as follows:

[0023] P 瓶 -P 进 ≥P 开

[0024] Among them, P 开 This indicates the preset opening pressure of the fourth electrically controlled valve.

[0025] Preferably, there are two fourth solenoid valves, which are respectively installed on the oil inlet / outlet and the oil outlet / inlet of the final stage compression cylinder, and the two fourth solenoid valves are communicatively connected to the same signal output terminal of the control module.

[0026] Preferably, the outlet of each of the plurality of gas storage cylinders is also connected to the inlet of the primary compression cylinder through their respective low-pressure gas recovery pipelines;

[0027] Accordingly, the electrically controlled valve assembly also includes a fifth electrically controlled valve installed on each low-pressure gas recovery pipeline.

[0028] Preferably, one end of the air inlet pipe near its air outlet is also connected to the air inlet of the gas dispenser via a gas supply branch pipe.

[0029] Preferably, the gas outlets of the gas supply branch pipes and each of the gas supply pipelines converge into a gas supply main pipe, and the gas outlet of the gas supply main pipe is connected to the gas outlet of the gas dispenser.

[0030] Preferably, a gas cooler is provided on the outlet pipe of each stage of the multi-stage compression cylinder, and the gas cooler is used to cool and reduce the temperature of the gas discharged from the respective compression cylinder.

[0031] Preferably, the hydraulic drive system includes a hydraulic oil tank, a fixed-displacement booster pump, a fixed-frequency motor, and a hydraulic directional valve. The output shaft of the fixed-frequency motor is driven and connected to the fixed-displacement booster pump. The oil inlet of the fixed-displacement booster pump is connected to the hydraulic oil tank through an oil inlet pipe. The oil outlet of the fixed-displacement booster pump is connected to the oil inlet of the hydraulic directional valve through an oil injection pipe. The oil outlet of the hydraulic directional valve is connected to the hydraulic oil tank through a return oil pipe. The two working oil ports of the hydraulic directional valve are respectively connected to the oil inlet / outlet and the oil outlet / inlet of each compression cylinder in the multi-stage compression cylinder through hydraulic pipes.

[0032] Preferably, the gas storage device includes a high-pressure gas storage cylinder and a medium-pressure gas storage cylinder, wherein the target gas storage pressure of the high-pressure gas storage cylinder is lower than the target gas storage pressure of the medium-pressure gas storage cylinder.

[0033] The second objective of this application is to provide a control method for a gas station unloading system.

[0034] The second objective of this application is achieved through the following technical solution:

[0035] A control method for a gas station unloading system as described in any one of the above claims includes the following steps:

[0036] S1, with the system power already turned on, control the gas station unloading system to enter standby mode;

[0037] S2, obtain the real-time gas storage pressure P of each gas storage cylinder of the gas storage device. 瓶 ;

[0038] S3, based on the real-time gas storage pressure P of each gas storage cylinder of the gas storage device. 瓶 Determine whether the preset unloading conditions are met. If yes, execute S4; otherwise, jump to S1.

[0039] S4, control the fourth solenoid valve to open, and control the second solenoid valves on each gas storage pipeline to work according to the preset gas filling control strategy, so as to fill each gas storage cylinder of the gas storage device in the order of the target gas storage pressure from high to low.

[0040] S5, obtain the intake pressure P of the penultimate stage compression cylinder. 进 ;

[0041] S6, based on the intake pressure P of the penultimate stage compression cylinder 进 and the real-time gas pressure P of the currently filled gas cylinder 瓶 To control the opening and closing state of the fourth solenoid valve, so that the final stage compression cylinder can be engaged or disengaged from compression operation, and S7 and S8 are executed in parallel during the operation of the multi-stage compression cylinder;

[0042] S7, determine whether the preset standby conditions are met. If yes, jump to S1; otherwise, jump to S5.

[0043] S8. Determine whether the long-tube trailer has been deflated. If yes, replace the long-tube trailer and proceed to S1. If no, proceed to S5.

[0044] In summary, this application discloses a gas station unloading system and its control method. The gas storage device of this gas station unloading system comprises multiple gas storage cylinders with different target storage pressures. The inlet of the first-stage compression cylinder in a multi-stage compression system is connected to a long-tube trailer via an inlet pipe. The outlet of the last-stage compression cylinder in the multi-stage compression system is connected to the inlet of the outlet pipe. The inlets of each of the multiple gas storage cylinders are connected to the outlets of the outlet pipes via their respective corresponding gas storage pipes. The outlets of each of the multiple gas storage cylinders are connected to their respective corresponding outlets via their respective gas storage pipes. The gas filling pipeline is connected to the gas dispenser's inlet. Each gas storage pipeline is equipped with a second electrically controlled valve, and at least one oil port of the final stage compressor cylinder is equipped with a fourth electrically controlled valve. The inlet pressure of the penultimate stage compressor cylinder is detected by an inlet pressure sensor, and the real-time gas storage pressure of each gas storage cylinder is detected by a storage pressure sensor on each cylinder. The control module then controls the second electrically controlled valves on each gas storage pipeline according to a preset filling control strategy, adjusting the gas storage pressure from high to low according to the target gas storage pressure. The gas cylinders of the gas storage device are filled sequentially. When the gas pressure in the long-tube trailer drops to a certain value, gas can be stored in a cylinder with a lower target storage pressure to further unload the low-pressure gas in the long-tube trailer, thereby increasing the unloading rate. The control module controls the opening and closing of the fourth electronic control valve based on the inlet pressure of the penultimate compression cylinder and the real-time storage pressure of the currently filled gas cylinder. This allows the final compression cylinder to engage or disengage. When the gas pressure in the long-tube trailer is low and the compression of the cylinders before the final compression cylinder cannot reach the filling pressure of the gas storage device, the final compression cylinder engages. Conversely, when the gas pressure in the long-tube trailer is high and the compression of the cylinders before the final compression cylinder can reach the filling pressure of the gas storage device, the final compression cylinder disengages. This increases the discharge volume per unit time of the compression system without increasing the hydraulic oil displacement or maintaining the same power consumption, improving the overall compression efficiency and thus enhancing the unloading efficiency of the unloading system. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the structure of a gas station unloading system in one embodiment of this application;

[0047] Figure 2 This is a circuit block diagram of a gas station unloading system according to one embodiment of this application;

[0048] Figure 3 This is a flowchart of a control method for a gas station unloading system in one embodiment of this application. Detailed Implementation

[0049] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] In the embodiments provided in this application, it should be understood that the disclosed methods and systems can be implemented in other ways. The system embodiments described below are merely illustrative. For example, the division of units and modules is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or modules can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, and can be electrical, mechanical, or other forms.

[0051] In addition, each functional unit in the various embodiments of this application can be integrated into a single processor, or each unit can be a separate device, or two or more units can be integrated into a single device; each functional unit in the various embodiments of this application can be implemented in hardware or in the form of hardware plus software functional units.

[0052] Those skilled in the art will understand that all or part of the steps of the following method embodiments can be implemented by program instructions and related hardware. The aforementioned program instructions can be stored in a computer-readable storage medium. When the program instructions are executed, they perform the steps of the following method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0054] like Figure 1 , Figure 2 As shown in the figure, this application provides a gas station unloading system. The system may include a multi-stage compression cylinder 1, a fixed-displacement hydraulic drive system 2, a gas storage device 3, a gas dispenser 4, an electrically controlled valve assembly 5, a gas pressure detection unit 6, and a control module 7. The hydraulic drive system 2, the gas dispenser 4, the electrically controlled valve assembly 5, and the gas pressure detection unit 6 are all communicatively connected to the control module 7.

[0055] The gas storage device 3 includes multiple gas storage cylinders 31 with different target gas storage pressures;

[0056] The multi-stage compression cylinder 1 includes multiple compression cylinders connected in series from the first stage to the last stage via an air supply pipeline. The air inlet of the first stage compression cylinder 11 in the multi-stage compression cylinder 1 is connected to the long tube trailer 8 via an air inlet pipeline, and the air outlet of the last stage compression cylinder 12 in the multi-stage compression cylinder 1 is connected to the air inlet of the air outlet pipeline.

[0057] The inlets of the multiple gas cylinders 31 are connected to the outlets of the gas outlets through their respective gas storage pipelines, and the outlets of the multiple gas cylinders 31 are connected to the inlets of the gas dispenser 4 through their respective gas filling pipelines.

[0058] The hydraulic drive system 2 is connected to the inlet / outlet and outlet / inlet of each compression cylinder in the multi-stage compression cylinder 1 via hydraulic pipelines.

[0059] The electronically controlled valve assembly 5 includes a first electronically controlled valve 51 located at one end of the air inlet of the air inlet pipeline, a second electronically controlled valve 52 located on each air storage pipeline, a third electronically controlled valve 53 located on each air filling pipeline, and a fourth electronically controlled valve 54 located on at least one oil port of the final stage compression cylinder 12.

[0060] The air pressure detection unit 6 includes a sensor installed at the air inlet of the penultimate compression cylinder to detect the air inlet pressure P of the penultimate compression cylinder. 进 The intake pressure sensor 61 and the gas cylinders 31 are used to detect the real-time gas storage pressure P of each gas cylinder 31. 瓶 Gas storage pressure sensor 62;

[0061] The control module 7 is configured to control the second electrically controlled valve 52 on each gas storage pipeline according to a preset gas filling control strategy, so as to fill each gas storage cylinder 31 of the gas storage device 3 in descending order of target gas storage pressure, and according to the inlet pressure P of the penultimate compression cylinder. 进 The real-time gas storage pressure P of the currently filled gas cylinder 31 瓶 This controls the opening and closing state of the fourth solenoid valve 54, so that the final stage compression cylinder 12 can be engaged in compression or disengaged from compression.

[0062] The working principle of the gas station unloading system in this embodiment is as follows:

[0063] During unloading, the control module 7 controls the first solenoid valve 51 to open and controls the second solenoid valve 52 on each gas storage pipeline to work according to the preset gas filling control strategy, so that each gas storage cylinder 31 of the gas storage device 3 is filled in order from high to low target gas storage pressure. If the gas pressure of the long tube trailer 8 still cannot reach the filling pressure of the gas storage cylinder 31 with the highest target gas storage pressure after being compressed by the multi-stage compression system, then the gas storage cylinder 31 with the second highest target gas storage pressure is filled, and so on. In this way, when the gas pressure of the long tube trailer 8 drops to a certain value, the gas storage cylinder 31 with the lower target gas storage pressure can continue to store gas to further unload the low-pressure gas in the long tube trailer 8, thereby improving the unloading rate of the long tube trailer 8.

[0064] During unloading, the intake pressure of the penultimate compression cylinder is detected by the intake pressure sensor 61 located at the intake port of the penultimate compression cylinder, and the real-time storage pressure of each storage cylinder 31 is detected by the storage pressure sensor 62 located on each storage cylinder 31. The control module 7 controls the opening and closing state of the fourth electronic control valve 54 based on the intake pressure of the penultimate compression cylinder and the real-time storage pressure of the currently filled storage cylinder 31, so that the final compression cylinder 12 is engaged or disengaged from compression. When the air pressure in the long tube trailer 8 is low and the compression of each stage of the compression cylinders before the final compression cylinder 12 cannot reach the filling pressure of the storage device 3, the final compression cylinder 12 is engaged in compression. Conversely, when the air pressure in the long tube trailer 8 is high and the compression of each stage of the compression cylinders before the final compression cylinder 12 can reach the filling pressure of the storage device 3, the final compression cylinder 12 is disengaged from compression. This allows the oil originally injected into the final stage compression cylinder 12 by the hydraulic drive system 2 to be injected into each stage of compression cylinders before the final stage compression cylinder 12. With the oil volume of each compression cylinder fixed, since the hydraulic oil displacement per unit time of the hydraulic drive system 2 is constant, increasing the oil injection volume per unit time of the compression cylinder will inevitably increase its reversing frequency, thereby increasing the overall discharge volume of the compressor. Since the hydraulic drive system 2 has not made any changes to the existing fixed displacement hydraulic drive scheme, the power consumption of the hydraulic drive system 2 per unit time will definitely be the same as before. However, since the overall discharge volume of the compression system per unit time increases while the power consumption remains unchanged, the discharge volume of the compression system per unit time increases without increasing the hydraulic oil displacement and keeping the power consumption constant. This improves the overall compression efficiency and discharge volume, thereby improving the unloading efficiency of the unloading system, that is, shortening the unloading time without increasing power consumption.

[0065] In summary, the embodiments of this application can effectively improve the unloading rate and efficiency of the gas station unloading system.

[0066] It should be noted that when the gas dispenser 4 refuels an external gas-using device, the control module 7 can control the third solenoid valve 53 on each gas refueling pipeline to work according to the preset gas refueling control strategy, so that the gas dispenser 4 can be supplied with gas through each gas cylinder 31 of the gas storage device 3 in the order of target gas storage pressure from high to low.

[0067] Specifically, in this embodiment, the control module 7 can be an industrial computer, a PLC controller, or an MCU controller.

[0068] In one embodiment, based on the intake pressure P of the penultimate compression cylinder 进 The real-time gas storage pressure P of the currently filled gas cylinder 31 瓶 Controlling the opening and closing state of the fourth solenoid valve 54 includes:

[0069] Determine the intake pressure P 进 and real-time gas storage pressure P 瓶 Does the preset valve opening condition meet?

[0070] If the conditions are met, the first control command is output to control the fourth electronic control valve 54 to open, connect the oil circuit of the final stage compression cylinder 12, and put the final stage compression cylinder 12 into compression work.

[0071] If the conditions are not met, a second control command is output to close the fourth electronically controlled valve 54, disconnecting the oil circuit of the final stage compression cylinder 12, thus causing the final stage compression cylinder 12 to cease compression operation.

[0072] The preset valve opening conditions are as follows:

[0073] P 瓶 -P 进 ≥P 开

[0074] Among them, P 开 This indicates the preset opening pressure of the fourth solenoid valve 54.

[0075] It should be noted that the preset opening pressure P of the fourth solenoid valve 54 开 The preset valve opening pressure can be calculated based on experimental measurements and corresponding calculation models, and set in advance in the control module 7. Different multi-stage compression cylinders 1 constitute different compression systems with different preset valve opening pressures.

[0076] Specifically, in this embodiment, P 开 =P 瓶max -P 进low +Pressure margin, among which

[0077] P 瓶max P represents the maximum operating pressure of the gas cylinder 31 currently being filled in the gas storage device 3 (i.e., the target gas storage pressure of the gas cylinder 31, which is a set value).进low This indicates the lower limit of the intake pressure of the long-tube trailer 8, which is just about not requiring the final compression cylinder 12 to be engaged in compression work (an empirical value obtained through experimental measurement, which is related to the maximum oil supply pressure of the hydraulic drive system 2, the friction between the piston and the inner wall of the cylinder of all compression cylinders in the multi-stage compression cylinder 1 during the reciprocating motion of the compression cylinder, the hydraulic oil pressure loss pressure caused by the friction loss generated by the self-weight of the compression cylinder rod, the surface area of ​​the piston oil side working surface of the penultimate compression cylinder, and the surface area of ​​the piston air side working surface of the penultimate compression cylinder). The pressure margin is a set value set according to the specific situation and / or experience when debugging the equipment, generally around 1 MPa.

[0078] The opening and closing of the fourth electronically controlled valve 54 is controlled according to the preset valve opening conditions of this embodiment, so as to more accurately control the timing of the final stage compression cylinder 12 to engage in compression and disengage from compression, thereby further improving the unloading efficiency of the unloading system.

[0079] In one embodiment, two fourth solenoid valves 54 are provided. The two fourth solenoid valves 54 are respectively installed on the oil inlet / outlet and oil outlet / inlet of the final stage compression cylinder 12, and the two fourth solenoid valves 54 are communicatively connected to the same signal output terminal of the control module 7.

[0080] It should be noted that since the final stage compression cylinder 12 has two oil ports on the oil side, and the oil inlet and outlet states of the two oil ports are constantly switching to control the compression cylinder to reverse compression, when the first oil port is the oil inlet, the second oil port is the oil outlet, and when the first oil port is the oil outlet, the second oil port is the oil inlet. Therefore, as long as one of the oil ports is closed by the fourth solenoid valve 54, the oil circuit of the final stage compression cylinder 12 is cut off. Therefore, the fourth solenoid valve 54 can be installed at any oil port of the final stage compression cylinder 12. However, when only one oil port is equipped with the fourth solenoid valve 54, and the oil port where the fourth solenoid valve 54 is installed is the oil outlet when the fourth solenoid valve 54 is closed, a small amount of oil will still enter the final stage compression cylinder 12 under the action of hydraulic oil pressure. Therefore, in order to ensure a better cut-off effect, in this embodiment, two fourth solenoid valves 54 are preferably used, that is, two fourth solenoid valves 54 control the opening and closing of the two oil ports of the final stage compression cylinder 12 respectively. In order to ensure the synchronization of the cut-off signals of the two fourth solenoid valves 54, the two fourth solenoid valves 54 are connected to the same signal output terminal of the control module 7. In this way, the two fourth solenoid valves 54 can be controlled to open and close synchronously by the same control signal output from the same signal output terminal of the control module 7, which also reduces the waste of the control port of the control module 7.

[0081] In one embodiment, the outlets of the multiple gas storage cylinders 31 are also connected to the inlet of the primary compression cylinder 11 through their respective low-pressure gas recovery pipelines.

[0082] Accordingly, the electrically controlled valve assembly 5 also includes a fifth electrically controlled valve 55 installed on each low-pressure gas recovery pipeline.

[0083] By connecting the outlet of the gas storage cylinder 31 to the inlet of the first-stage compression cylinder 11 through a low-pressure gas recovery pipeline, and installing a fifth electrically controlled valve 55 on the low-pressure gas recovery pipeline, when the gas pressure in the gas storage cylinder 31 in the gas storage device 3 is too low to meet the gas dispenser 4's holiday needs, the fifth electrically controlled valve 55 on the corresponding gas storage cylinder 31 is opened. The gas in the gas storage cylinder 31 is then compressed and pressurized by the same multi-stage compression cylinder 1 used for unloading and stored in other gas storage cylinders 31 in the gas storage device 3. This completes the transfer and compression of the gas in the low-pressure gas storage cylinder 31, improving gas utilization. Furthermore, when the gas pressure in each gas storage cylinder 31 in the gas storage device 3 is insufficient to supply gas to the gas dispenser 4, and there is no long-tube trailer 8 to supply gas to the gas dispenser 4, the low-pressure gas recovery and pressurization structure can be used to achieve emergency gas supply to the gas dispenser 4.

[0084] In one embodiment, the end of the intake pipe near its outlet is also connected to the intake port of the gas dispenser 4 via a gas supply branch pipe. In this way, the gas output from the long-tube trailer 8 can be directly supplied to the gas dispenser 4 through the intake pipe and the gas supply branch pipe. Thus, when the gas storage device 3 in the gas station is full but the gas in the long-tube trailer 8 has not been completely unloaded, the long-tube trailer 8 can directly supply gas to the gas dispenser 4 to further unload the gas in the long-tube trailer 8.

[0085] In one embodiment, the outlets of the refueling branch pipes and various refueling pipelines are converged into a main refueling pipe, and the outlet of the main refueling pipe is connected to the outlet of the refueling machine 4. Since the refueling machine 4 has only one inlet, by converging the outlets of the refueling branch pipes and various refueling pipelines into a main refueling pipe and connecting the outlet of the main refueling pipe to the outlet of the refueling machine 4, the internal piping arrangement of the refueling machine 4 can be reduced.

[0086] In one embodiment, a gas cooler 9 is installed on the outlet pipe of each stage of the multi-stage compression cylinder 1. The gas cooler 9 is used to cool and reduce the temperature of the gas discharged from each corresponding compression cylinder. By installing gas coolers 9 on the outlet pipe of each stage of the multi-stage compression cylinder 1, the compressed gas output from the corresponding compression cylinder is cooled by each gas cooler 9 during the unloading process of the long-tube trailer 8, thereby increasing the gas density. This allows the gas storage cylinder 31 to store more gas under the same gas pressure, further improving the unloading rate of the long-tube trailer 8.

[0087] In one embodiment, the hydraulic drive system 2 includes a hydraulic oil tank 21, a fixed-displacement booster pump 22, a fixed-frequency motor 23, and a hydraulic directional valve 24. The output shaft of the fixed-frequency motor 23 is driven and connected to the fixed-displacement booster pump 22. The oil inlet of the fixed-displacement booster pump 22 is connected to the hydraulic oil tank 21 through an oil inlet pipe. The oil outlet of the fixed-displacement booster pump 22 is connected to the oil inlet of the hydraulic directional valve 24 through an oil injection pipe. The oil outlet of the hydraulic directional valve 24 is connected to the hydraulic oil tank 21 through a return oil pipe. The two working oil ports of the hydraulic directional valve 24 are respectively connected to the oil inlet / outlet and the oil outlet / inlet of each compression cylinder in the multi-stage compression cylinder 1 through hydraulic pipes.

[0088] When the long-tube trailer 8 is unloading air, the control module 7 controls the fixed-frequency electric start, the fixed-frequency motor 23 drives the fixed-frequency booster pump to work, and supplies oil to the hydraulic reversing valve 24 through the oil inlet pipe. The hydraulic reversing valve 24 supplies oil to the multi-stage compression cylinder 1 through the hydraulic pipeline, so that each stage of the multi-stage compression cylinder 1 compresses synchronously and reverses synchronously. The return oil of the multi-stage compression cylinder 1 flows to the hydraulic reversing valve 24 through the hydraulic pipeline and then flows back to the hydraulic oil tank 21 through the return oil pipeline.

[0089] In one embodiment, the gas storage device 3 includes a high-pressure gas cylinder 31 and a medium-pressure gas cylinder 31, with the target gas storage pressure of the high-pressure gas cylinder 31 being lower than that of the medium-pressure gas cylinder 31. When the long-tube trailer 8 is unloading, the high-pressure gas cylinder 31 is filled first. If the gas pressure of the long-tube trailer 8 is insufficient to fill the high-pressure gas cylinder 31, the medium-pressure gas cylinder 31 is filled. Thus, by adding a medium-pressure gas cylinder 31 and changing the corresponding unloading control logic based on the existing technology, the unloading rate of the long-tube trailer 8 is improved.

[0090] This application also provides a control method for a gas station unloading system. This method is implemented based on the gas station unloading system in any of the above embodiments, and the method may include the following steps:

[0091] S1, when the system power is on, control the gas station unloading system to enter standby mode;

[0092] S2, obtain the real-time gas storage pressure P of each gas storage cylinder in the gas storage device. 瓶 ;

[0093] S3, based on the real-time gas storage pressure P of each gas storage cylinder in the gas storage device. 瓶 Determine whether the preset unloading conditions are met. If yes, execute S4; otherwise, jump to S1.

[0094] Specifically, in this embodiment, meeting the preset unloading condition means that the pressure of the gas storage cylinder with the highest target gas storage pressure in the gas storage device is lower than the start-up pressure setting value of the unloading system. For CNG, this start-up pressure setting value is typically 21 MPa, and for hydrogen, it is typically 38 MPa.

[0095] S4 controls the fourth solenoid valve to open and controls the second solenoid valves on each gas storage pipeline to work according to the preset gas filling control strategy, so as to fill each gas storage cylinder of the gas storage device in the order of target gas storage pressure from high to low.

[0096] Specifically, if the air pressure in the long-tube trailer still cannot reach the filling pressure of the gas cylinder with the highest target gas storage pressure after being compressed by the multi-stage compression system, then the gas cylinder with the second highest target gas storage pressure is filled, and so on. In this way, when the air pressure in the long-tube trailer drops to a certain value, the gas cylinder with the lower target gas storage pressure can continue to store gas to further unload the low-pressure gas in the long-tube trailer, thereby improving the unloading rate of the long-tube trailer.

[0097] S5, obtain the intake pressure P of the penultimate compression cylinder. 进 ;

[0098] S6, based on the intake pressure P of the penultimate compression cylinder 进 and the real-time gas pressure P of the currently filled gas cylinder 瓶 To control the opening and closing state of the fourth solenoid valve, so as to engage or disengage the final stage compression cylinder, and to execute S7 and S8 in parallel during the operation of the multi-stage compression cylinder;

[0099] Specifically, based on the intake pressure P of the penultimate compression cylinder 进 and the real-time gas pressure P of the currently filled gas cylinder 瓶 The specific process for controlling the opening and closing state of the fourth electrically controlled valve is as follows:

[0100] Determine the intake pressure P 进 and real-time gas storage pressure P 瓶 Does the preset valve opening condition meet?

[0101] If the conditions are met, the first control command is output to control the fourth electronic control valve to open, connect the oil circuit of the final stage compression cylinder, and enable the final stage compression cylinder to engage in compression work.

[0102] If the conditions are not met, a second control command is output to close the fourth electronically controlled valve, disconnecting the oil circuit of the final stage compression cylinder and causing the final stage compression cylinder to cease compression operation.

[0103] The preset valve opening conditions are as follows:

[0104] P 瓶 -P进 ≥P 开

[0105] Among them, P 开 This indicates the preset opening pressure of the fourth electrically controlled valve.

[0106] It should be noted that the preset opening pressure P of the fourth electrically controlled valve 开 The preset valve opening pressure can be obtained based on experimental measurements and corresponding calculation models, and set in advance in the control module. Different multi-stage compression cylinders have different preset valve opening pressures.

[0107] Specifically, in this embodiment, P 开 =P 瓶max -P 进low +Pressure margin, among which

[0108] P 瓶max P represents the maximum operating pressure of the gas cylinder currently filled in the gas storage device (i.e., the target gas storage pressure of the gas cylinder, which is a set value). 进low This indicates the lower limit of the intake pressure for a long-tube trailer that does not require the final compression cylinder to engage in compression (an empirical value obtained through experimental measurement, which is related to the maximum oil supply pressure of the hydraulic drive system, the friction between the piston and the inner wall of the cylinder in all compression cylinders during the reciprocating motion of the compression cylinder, the hydraulic oil pressure loss caused by the friction loss generated by the weight of the compression cylinder rod, the surface area of ​​the piston oil side working surface of the penultimate compression cylinder, and the surface area of ​​the piston air side working surface of the penultimate compression cylinder). The pressure margin is a set value set according to the specific conditions and / or experience during equipment commissioning, generally around 1 MPa.

[0109] The opening and closing of the fourth electrically controlled valve is controlled according to the preset valve opening conditions of this embodiment, so as to more accurately control the timing of the final stage compression cylinder to engage and disengage from compression, thereby further improving the unloading efficiency of the unloading system.

[0110] S7, determine whether the preset standby conditions are met. If yes, jump to S1; otherwise, jump to S5.

[0111] Specifically, meeting the preset standby conditions means that the pressure of the gas cylinder with the lowest target gas storage pressure in the gas storage device is greater than the standby pressure setting value of the unloading system. For CNG, the standby pressure setting value is usually 23 MPa, and for hydrogen, the standby pressure setting value is usually 43 MPa.

[0112] S8 determines whether the long-tube trailer has been deflated. If so, replace the long-tube trailer and proceed to S1. If not, proceed to S5.

[0113] The control method in this embodiment can effectively improve the unloading rate and efficiency of the gas station's unloading system.

[0114] It should be noted that the parts of the control method for the gas station unloading system not mentioned in the embodiments are the same as those in the embodiments of the gas station unloading system described above, and will not be repeated here.

[0115] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0116] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0117] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly using hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0118] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas unloading system for a gas station, characterized in that, The system includes a multi-stage compression cylinder, a fixed-displacement hydraulic drive system, an air storage device, a gas dispenser, an electrically controlled valve assembly, a gas pressure detection unit, and a control module. The hydraulic drive system, gas dispenser, electrically controlled valve assembly, and gas pressure detection unit are all communicatively connected to the control module. The gas storage device includes multiple gas storage cylinders with different target gas storage pressures. The multi-stage compression cylinder includes multiple compression cylinders connected in series from the first stage to the last stage via an air supply pipeline. The air inlet of the first stage compression cylinder is connected to the long tube trailer via an air inlet pipeline, and the air outlet of the last stage compression cylinder is connected to the air inlet of the air outlet pipeline. The inlet of each of the plurality of gas storage cylinders is connected to the outlet of the outlet pipeline through its respective gas storage pipeline, and the outlet of each of the plurality of gas storage cylinders is connected to the inlet of the gas dispenser through its respective gas filling pipeline. The hydraulic drive system is connected to the inlet / outlet and outlet / inlet of each compression cylinder in the multi-stage compression cylinder via hydraulic pipelines. The electronically controlled valve group includes a first electronically controlled valve disposed at one end of the air inlet of the air inlet pipeline, a second electronically controlled valve disposed on each air storage pipeline, a third electronically controlled valve disposed on each air filling pipeline, and a fourth electronically controlled valve disposed on at least one oil port of the final stage compression cylinder. The air pressure detection unit includes an air inlet for detecting the inlet pressure P of the penultimate compression cylinder. 进 The intake pressure sensor is installed on each gas cylinder to detect the real-time gas pressure P of each gas cylinder. 瓶 The gas storage pressure sensor; The control module is configured to control the second electrically controlled valves on each gas storage pipeline according to a preset inflation control strategy, so as to sequentially fill each gas cylinder of the gas storage device in descending order of the target gas storage pressure, and according to the inlet pressure P of the penultimate compression cylinder. 进 and the real-time gas pressure P of the currently filled gas cylinder 瓶 This controls the opening and closing state of the fourth electrically controlled valve, so that the final stage compression cylinder can be engaged or disengaged from compression operation. Wherein, according to the intake pressure P of the penultimate stage compression cylinder 进 and the real-time gas pressure P of the currently filled gas cylinder 瓶 Controlling the opening and closing state of the fourth electrically controlled valve includes: Determine the intake pressure P 进 and real-time gas storage pressure P 瓶 Does the preset valve opening condition meet? If the conditions are met, the first control command is output to control the fourth electronically controlled valve to open, connect the oil circuit of the final stage compression cylinder, and enable the final stage compression cylinder to engage in compression work. If the conditions are not met, a second control command is output to close the fourth electrically controlled valve, disconnecting the oil circuit of the final stage compression cylinder and causing the final stage compression cylinder to cease compression operation. The preset valve opening conditions are as follows: P 瓶 -P 进 ≥P 开 Among them, P 开 This indicates the preset opening pressure of the fourth electrically controlled valve.

2. The gas station unloading system according to claim 1, characterized in that, There are two fourth solenoid valves, which are respectively installed on the oil inlet / outlet and the oil outlet / inlet of the final stage compression cylinder, and the two fourth solenoid valves are communicatively connected to the same signal output terminal of the control module.

3. The gas station unloading system according to claim 1, characterized in that, The outlets of each of the multiple gas storage cylinders are also connected to the inlet of the primary compression cylinder through their respective low-pressure gas recovery pipelines. Accordingly, the electrically controlled valve assembly also includes a fifth electrically controlled valve installed on each low-pressure gas recovery pipeline.

4. The gas station unloading system according to claim 1 or 3, characterized in that, The end of the air inlet pipe near its outlet is also connected to the air inlet of the gas dispenser via a gas dispensing branch pipe.

5. The gas station unloading system according to claim 4, characterized in that, The gas outlets of the gas supply branch pipes and each of the gas supply lines converge into a main gas supply pipe, and the outlet of the main gas supply pipe is connected to the outlet of the gas dispenser.

6. The gas station unloading system according to claim 1, 3, or 5, characterized in that, Gas coolers are installed on the outlet pipes of each stage of the multi-stage compression cylinder, and the gas coolers are used to cool and reduce the temperature of the gas discharged from the respective compression cylinder.

7. The gas station unloading system according to claim 1, 3, or 5, characterized in that, The hydraulic drive system includes a hydraulic oil tank, a fixed-displacement booster pump, a fixed-frequency motor, and a hydraulic directional valve. The output shaft of the fixed-frequency motor is driven and connected to the fixed-displacement booster pump. The oil inlet of the fixed-displacement booster pump is connected to the hydraulic oil tank through an oil inlet pipe. The oil outlet of the fixed-displacement booster pump is connected to the oil inlet of the hydraulic directional valve through an oil injection pipe. The oil outlet of the hydraulic directional valve is connected to the hydraulic oil tank through a return oil pipe. The two working oil ports of the hydraulic directional valve are respectively connected to the oil inlet / outlet and the oil outlet / inlet of each compression cylinder in the multi-stage compression cylinder through hydraulic pipes.

8. The gas station unloading system according to claim 1, 3, or 5, characterized in that, The gas storage device includes a high-pressure gas storage cylinder and a medium-pressure gas storage cylinder, wherein the target gas storage pressure of the high-pressure gas storage cylinder is lower than the target gas storage pressure of the medium-pressure gas storage cylinder.

9. A control method for a gas station unloading system according to any one of claims 1-8, characterized in that, Includes the following steps: S1, with the system power already turned on, control the gas station unloading system to enter standby mode; S2, obtain the real-time gas storage pressure P of each gas storage cylinder of the gas storage device. 瓶 ; S3, based on the real-time gas storage pressure P of each gas storage cylinder of the gas storage device. 瓶 Determine whether the preset unloading conditions are met. If yes, execute S4; otherwise, jump to S1. S4, control the fourth solenoid valve to open, and control the second solenoid valves on each gas storage pipeline to work according to the preset gas filling control strategy, so as to fill each gas storage cylinder of the gas storage device in the order of the target gas storage pressure from high to low. S5, obtain the intake pressure P of the penultimate stage compression cylinder. 进 ; S6, based on the intake pressure P of the penultimate stage compression cylinder 进 and the real-time gas pressure P of the currently filled gas cylinder 瓶 To control the opening and closing state of the fourth solenoid valve, so that the final stage compression cylinder can be engaged or disengaged from compression operation, and S7 and S8 are executed in parallel during the operation of the multi-stage compression cylinder; S7, determine whether the preset standby conditions are met. If yes, jump to S1; otherwise, jump to S5. S8. Determine whether the long-tube trailer has been deflated. If yes, replace the long-tube trailer and proceed to S1. If no, proceed to S5.

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