Gas station gas discharging system and control method thereof

Abstract

The invention discloses a gas station gas discharging system and a control method thereof.The gas station gas discharging system comprises a multi-stage compression cylinder, a hydraulic driving system with the fixed displacement, a gas storage device, a gas dispenser, an electric control valve set, a gas pressure detection unit and a control module, and the hydraulic driving system, the gas dispenser, the electric control valve set and the gas pressure detection unit are in communication connection with the control module; the gas storage device comprises a plurality of gas storage bottles with different target gas storage pressures; the electric control valve group comprises second electric control valves arranged on the gas storage pipelines and fourth electric control valves arranged on at least one oil port of the final-stage compression cylinder; and during gas discharging, the control module can control the second electric control valves on the gas storage pipelines to work according to a preset gas charging control strategy, and the opening and closing states of the fourth electric control valves are controlled according to the gas inlet pressure of the last but one stage of compression cylinder and the real-time gas storage pressure of the currently filled gas storage bottle. The gas discharging rate and the gas discharging efficiency of the gas discharging system of the gas filling station can be effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of gas unloading control at a gas filling station, and in particular to a gas unloading system at a gas filling station and a control method thereof. Background Art

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

[0003] When a tube trailer unloads gas at a gas station, the gas in the tube trailer is compressed and pressurized by the gas compression system in the gas station and then transported to the gas storage device in the gas station for storage. During the unloading process of the tube trailer, the gas pressure in its gas storage tank continues to drop. The gas storage pressure of existing gas storage devices is generally fixed, and the compression ratio of the same compression system is also fixed. When the gas pressure of the tube trailer drops to a certain pressure, the compression of the compression system is lower than the gas pressure in the gas storage device, and further inflation cannot be achieved. At this time, the tube trailer can no longer be unloaded.

[0004] When the gas pressure in the gas storage device reaches a certain value and cannot be further inflated, there are usually two ways to deal with it: one is that the long tube leaves the gas filling station to continue to fill 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 that the long tube trailer stops at the gas filling station and waits for the gas storage device to fill gas to external gas-using equipment (such as gas fuel vehicles) through the gas filling machine to reduce the gas pressure in the gas storage device to a lower pressure value, and then the air pressure in the long tube trailer is compressed again through the compression system to inflate the gas storage device, thereby increasing the unloading rate of the long tube trailer. However, this will significantly increase the parking time of the long tube trailer and will occupy a large space, which will also cause a waste of transportation resources and space resources.

[0005] In addition, the compression system of the gas station generally uses a multi-stage compression cylinder for compression. Since the hydraulic drive system cost of the variable displacement compression system is relatively high, the gas station usually uses a fixed displacement compression system, and the output hydraulic oil displacement is fixed per unit time. Therefore, when all the compression cylinders of the multi-stage compression cylinder are working at the same time, the switching frequency is fixed and the compressed exhaust volume per unit time is fixed. When the long-tube trailer starts to unload gas, the gas pressure in its gas tank is relatively high, which makes the intake pressure of the multi-stage compression system relatively high. The compression cylinder before the last-stage compression cylinder can usually reach the charging pressure of the gas storage device after compression. When the existing gas station unloading system is unloading gas, each compression cylinder of the multi-stage compression cylinder is always in a working state. Therefore, in the initial stage of the long-tube trailer starting to unload gas, since the compression cylinder before the last-stage compression cylinder can usually reach the charging pressure of the gas storage device after compression, the last-stage compression cylinder does not actually compress the gas, that is, the last-stage compression cylinder does not do work. On the contrary, the reciprocating motion of its piston needs to overcome the friction between the piston and the cylinder body and consumes the energy transmitted by the hydraulic oil, thereby increasing useless energy loss of the hydraulic drive system and reducing the working efficiency of the compression cylinders before the last-stage compression cylinder, that is, reducing the overall compression efficiency of the compression system, and further reducing the unloading efficiency of the unloading system.

[0006] Therefore, how to improve the gas unloading rate and gas unloading efficiency of the gas unloading system of a gas filling station is a problem to be solved urgently in this field. Summary of the invention

[0007] In order to solve the above technical problems, the present application provides a gas station unloading system and a control method thereof, which can effectively improve the unloading rate and unloading efficiency of the gas station unloading system.

[0008] The first object of the present application is to provide a gas unloading system for a gas filling station.

[0009] The above-mentioned application objective 1 of the present application is achieved through the following technical solutions:

[0010] A gas unloading system for a gas filling station includes a multi-stage compression cylinder, a fixed displacement hydraulic drive system, a gas storage device, a gas filling machine, an electric control valve group, an air pressure detection unit and a control module, wherein the hydraulic drive system, the gas filling machine, the electric control valve group and the air pressure detection unit are respectively connected to the control module for communication, wherein:

[0011] The gas storage device comprises a plurality of gas storage cylinders with different target gas storage pressures;

[0012] The multi-stage compression cylinder comprises a plurality of compression cylinders connected in series from the first stage to the last stage through an air transmission pipeline, the air inlet of the first stage compression cylinder in the multi-stage compression cylinder is connected to the long tube trailer through the air inlet pipeline, and the air outlet of the last stage compression cylinder in the multi-stage compression cylinder is connected to the air inlet of the air outlet pipeline;

[0013] The gas inlets of the multiple gas cylinders are connected to the gas outlets of the gas outlet pipelines through their corresponding gas storage pipelines, and the gas outlets of the multiple gas cylinders are connected to the gas inlet of the gas dispenser through their corresponding gas filling pipelines;

[0014] The hydraulic drive system is connected to the oil inlet / outlet and the oil outlet / inlet of each compression cylinder in the multi-stage compression cylinder through a hydraulic pipeline;

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

[0016] The air pressure detection unit includes a pressure sensor disposed at the air inlet of the penultimate compression cylinder for detecting the air inlet pressure P of the penultimate compression cylinder. 进 The intake pressure sensor and the real-time gas storage pressure P of each gas storage cylinder are arranged on each gas storage cylinder to detect the real-time gas storage pressure P of each gas storage cylinder. 瓶 Gas storage pressure sensor;

[0017] The control module is configured to control the operation of the second electric control valve on each gas storage pipeline according to a preset gas charging control strategy, so as to fill each gas storage cylinder of the gas storage device in order from high to low according to the target gas storage pressure, and according to the intake pressure P of the second-to-last compression cylinder. 进 and the real-time gas storage pressure P of the currently filled gas cylinder 瓶 To control the opening and closing state of the fourth electric control valve, so that the final stage compression cylinder is put into compression cylinder operation or exits compression operation.

[0018] Preferably, the intake pressure P of the penultimate compression cylinder 进 and the real-time gas storage 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 Whether the preset valve opening conditions are met,

[0020] If the conditions are met, the first control instruction is output to control the fourth electric control valve to open, connect the oil circuit of the final compression cylinder, and put the final compression cylinder into compression operation;

[0021] If it is not satisfied, the second control instruction is output to control the fourth electric control valve to close, disconnect the oil circuit of the final compression cylinder, and make the final compression cylinder quit compression work.

[0022] Wherein, the preset valve opening conditions are as follows:

[0023] P 瓶 -P 进 ≥P 开

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

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

[0026] Preferably, the gas outlets of the plurality of gas storage cylinders are respectively connected to the gas inlet of the first-stage compression cylinder through their corresponding low-pressure gas recovery pipelines;

[0027] Correspondingly, the electrically-controlled valve group further includes a fifth electrically-controlled valve arranged on each low-pressure gas recovery pipeline.

[0028] Preferably, one end of the air inlet pipeline close to its air outlet is also connected to the air inlet of the gas filling machine through a gas filling branch pipe.

[0029] Preferably, the gas filling branch pipes and the gas outlets of each of the gas filling pipelines are gathered into a gas filling main pipe, and the gas outlet of the gas filling main pipe is connected to the gas outlet of the gas filling machine.

[0030] Preferably, a gas cooler is provided on the pipeline of the gas outlet of each stage of the multi-stage compression cylinder, and the gas cooler is used to cool down the gas discharged from the corresponding compression cylinder.

[0031] Preferably, the hydraulic drive system includes a hydraulic oil tank, a quantitative booster pump, a fixed-frequency motor and a hydraulic reversing valve. The output shaft of the fixed-frequency motor is drivingly connected to the quantitative booster pump. The oil inlet of the quantitative booster pump is connected to the hydraulic oil tank through an oil inlet pipeline. The oil outlet of the quantitative booster pump is connected to the oil inlet of the hydraulic reversing valve through an oil filling pipeline. The oil outlet of the hydraulic reversing valve is connected to the hydraulic oil tank through an oil return pipeline. The two working oil ports of the hydraulic reversing valve are respectively connected to the oil inlet / outlet and oil outlet / inlet of each compression cylinder in the multi-stage compression cylinder through hydraulic pipelines.

[0032] Preferably, the gas storage device comprises a high-pressure gas storage cylinder and a medium-pressure gas storage cylinder, and 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 object of the present application is to provide a control method for a gas unloading system of a gas filling station.

[0034] The second application objective of the present application is achieved through the following technical solutions:

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

[0036] S1, when the system power supply is started, controlling the gas station unloading system to enter a standby state;

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

[0038] S3, according to the real-time gas storage pressure P of each gas storage cylinder of the gas storage device 瓶 Determine whether the preset gas unloading condition is currently met. If so, execute S4; if not, jump to S1;

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

[0040] S5, obtaining the intake pressure P of the penultimate compression cylinder 进 ;

[0041] S6, according to the intake pressure P of the second-to-last compression cylinder 进 and the real-time gas storage pressure P of the currently filled gas cylinder 瓶 to control the opening and closing state of the fourth electric control valve, so that the last stage compression cylinder starts compression cylinder operation or quits compression operation, and in the operation process of the multi-stage compression cylinder, S7 and S8 are executed in parallel;

[0042] S7, judging whether the preset standby condition is met, if yes, jumping to S1, if no, jumping to S5;

[0043] S8, judging whether the long tube trailer has been completely unloaded, if so, replacing the long tube trailer and jumping to S1, if not, jumping to S5.

[0044] In summary, the present application discloses a gas unloading system for a gas filling station and a control method thereof. The gas storage device of the gas unloading system for a gas filling station is provided with a plurality of gas storage cylinders with different target gas storage pressures. The gas inlet of a first-stage compression cylinder in a multi-stage compression cylinder is connected to a long tube trailer through an air inlet pipeline, the gas outlet of a last-stage compression cylinder in the multi-stage compression cylinder is connected to the gas inlet of the gas outlet pipeline, the gas inlets of the plurality of gas storage cylinders are respectively connected to the gas outlet of the gas outlet pipeline through their respective corresponding gas storage pipelines, and the gas outlets of the plurality of gas storage cylinders are respectively connected to the gas outlets of the gas outlet pipeline through their respective corresponding gas storage pipelines. The gas filling pipeline is connected to the gas inlet of the gas filling machine, a second electrically controlled valve is arranged on each gas storage pipeline, a fourth electrically controlled valve is arranged on at least one oil port of the final compression cylinder, and the gas inlet pressure sensor arranged at the gas inlet of the penultimate compression cylinder is used to detect the gas inlet pressure of the penultimate compression cylinder, and the gas storage pressure sensor arranged on each gas storage cylinder is used to detect the real-time gas storage pressure of each gas storage cylinder, and the control module controls the second electrically controlled valve on each gas storage pipeline to work according to the preset inflation control strategy, so as to adjust 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 in sequence, so that when the gas pressure of the long tube trailer drops to a certain value, the gas cylinder with a lower target gas storage pressure can be used to continue to store gas to further discharge the low-pressure gas in the long tube trailer, thereby improving the gas discharge rate of the long tube trailer, and the control module controls the opening and closing state of the fourth electric control valve according to the intake pressure of the second-to-last compression cylinder and the real-time gas storage pressure of the gas cylinder currently filled, so that the last-stage compression cylinder is put into compression cylinder operation or exits compression operation, so that when the gas pressure in the long tube trailer is low and the gas charging pressure of the gas storage device cannot be reached by compression of the various compression cylinders before the final compression cylinder, the final-stage compression cylinder is put into compression operation, and when the gas pressure in the long tube trailer is high and the gas charging pressure of the gas storage device can be reached by compression of the various compression cylinders before the final compression cylinder, the final-stage compression cylinder is exited from compression operation, so that the exhaust volume per unit time of the compression system is increased without increasing the hydraulic oil displacement and the power consumption remains unchanged, the overall compression efficiency is improved, the exhaust volume is increased, and the gas discharge efficiency of the gas discharge system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0047] Figure 2 This is a circuit principle block diagram of a gas filling station gas unloading system in one embodiment of the present application;

[0048] Figure 3 This is a flow chart of a control method for a gas unloading system at a gas filling station in one embodiment of the present application. DETAILED DESCRIPTION

[0049] In order 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 part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

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

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

[0052] A person skilled in the art can understand that all or part of the steps of the following method embodiments can be completed 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, the steps of the following method embodiments are executed; and the aforementioned storage medium includes: a mobile storage device, a read-only memory (ROM), a magnetic disk or an optical disk, and other media that can store program codes.

[0053] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "multiple" and "several" mean two or more, unless otherwise clearly and specifically defined.

[0054] like Figure 1 , Figure 2 As shown, the embodiment of the present application provides a gas station unloading system, which 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 electric control valve group 5, an air pressure detection unit 6 and a control module 7. The hydraulic drive system 2, the gas dispenser 4, the electric control valve group 5 and the air pressure detection unit 6 are respectively connected to the control module 7 for communication, wherein:

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

[0056] The multi-stage compression cylinder 1 includes a plurality of compression cylinders connected in series from the first stage to the last stage through a gas transmission 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 through the 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 gas inlets of the multiple gas cylinders 31 are connected to the gas outlets of the gas outlet pipelines through their corresponding gas storage pipelines, and the gas outlets of the multiple gas cylinders 31 are connected to the gas inlets of the gas dispenser 4 through their corresponding gas filling pipelines.

[0058] The hydraulic drive system 2 is connected to the oil inlet / outlet and the oil outlet / inlet of each compression cylinder in the multi-stage compression cylinder 1 through a hydraulic pipeline;

[0059] The electric control valve group 5 includes a first electric control valve 51 arranged at one end of the air inlet of the air inlet pipeline, a second electric control valve 52 arranged on each air storage pipeline, a third electric control valve 53 arranged on each air filling pipeline, and a fourth electric control valve 54 arranged on at least one oil port of the final compression cylinder 12;

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

[0061] The control module 7 is configured to control the operation of the second electric control valve 52 on each gas storage pipeline according to a preset gas charging control strategy, so as to charge each gas storage cylinder 31 of the gas storage device 3 in order from high to low according to the target gas storage pressure, and according to the intake pressure P of the second-to-last compression cylinder. 进 and the real-time gas storage pressure P of the currently filled gas storage cylinder 31 瓶 To control the opening and closing state of the fourth electrically controlled valve 54, so that the final stage compression cylinder 12 can be put into compression cylinder operation or exit compression operation.

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

[0063] When unloading gas, the control module 7 controls the first electrically controlled valve 51 to open, and controls the second electrically controlled valve 52 on each gas storage pipeline to work according to a preset gas filling control strategy, so as to fill each gas cylinder 31 of the gas storage device 3 in order from high to low according to the target gas storage pressure. When the gas pressure of the long tube trailer 8 still cannot reach the filling pressure of the gas cylinder 31 with the highest target gas storage pressure after being compressed by the multi-stage compression system, the gas 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 cylinder 31 with a lower target gas storage pressure can be used to 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] When unloading gas, the intake pressure of the penultimate compression cylinder is detected by the intake pressure sensor 61 arranged at the air inlet of the penultimate compression cylinder, and the real-time gas storage pressure of each gas cylinder 31 is detected by the gas storage pressure sensor 62 arranged on each gas cylinder 31. The control module 7 controls the opening and closing state of the fourth electric control valve 54 according to the intake pressure of the penultimate compression cylinder and the real-time gas storage pressure of the currently filled gas cylinder 31, so as to put the final compression cylinder 12 into compression cylinder operation or exit compression operation. Therefore, when the air pressure in the long tube trailer 8 is low and the inflation pressure of the gas storage device 3 cannot be reached by compression of the various compression cylinders before the final compression cylinder 12, the final compression cylinder 12 is put into compression operation. When the air pressure in the long tube trailer 8 is high and the inflation pressure of the gas storage device 3 can be reached by compression of the various compression cylinders before the final compression cylinder 12, the final compression cylinder 12 is exited from compression operation. , thereby injecting the oil originally injected into the final compression cylinder 12 of the hydraulic drive system 2 into the compression cylinders of each stage before the final compression cylinder 12. When the volume on the oil side of each compression cylinder is fixed, since the hydraulic oil displacement per unit time of the hydraulic drive system 2 is constant, increasing the oil injection per unit time on the oil side of the compression cylinder is bound to increase its switching frequency, thereby increasing the overall exhaust volume of the compressor. Since the hydraulic drive system 2 is equivalent to the existing fixed-displacement hydraulic drive scheme, the power consumption per unit time of the hydraulic drive system 2 must be the same as before. However, since the overall exhaust volume per unit time of the compression system increases and the power consumption remains unchanged, the exhaust volume per unit time of the compression system increases without increasing the hydraulic oil displacement and the power consumption remains unchanged, the overall compression efficiency is improved, the exhaust volume increases, and the unloading efficiency of the unloading system is improved, that is, the unloading time is shortened without increasing the power consumption.

[0065] In summary, it can be seen that the embodiments of the present application can effectively improve the gas unloading rate and gas unloading efficiency of the gas unloading system of the gas filling station.

[0066] It should be noted that when the gas filling machine 4 fills the external gas-using equipment with gas, the control module 7 can control the third electrically controlled valve 53 on each gas filling pipeline to operate according to the preset gas filling control strategy, so as to supply gas to the gas filling machine 4 through each gas cylinder 31 of the gas storage device 3 in sequence according to the target gas storage pressure from high to low.

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

[0068] In one embodiment, according to the intake pressure P of the second-to-last compression cylinder 进 and the real-time gas storage pressure P of the currently filled gas storage cylinder 31 瓶 To control the opening and closing state of the fourth electrically controlled valve 54 includes:

[0069] Determine the intake pressure P 进 and real-time gas storage pressure P 瓶 Whether the preset valve opening conditions are met,

[0070] If the conditions are met, the first control instruction is output to control the fourth electric control valve 54 to open, connect the oil circuit of the final compression cylinder 12, and put the final compression cylinder 12 into compression operation;

[0071] If it is not satisfied, the second control instruction is output to control the fourth electric control valve 54 to close, disconnect the oil circuit of the final compression cylinder 12, and make the final compression cylinder 12 quit compression work.

[0072] Among them, the preset valve opening conditions are as follows:

[0073] P 瓶 -P 进 ≥P 开

[0074] Among them, P 开 represents the preset valve opening pressure of the fourth electrically controlled valve 54 .

[0075] It should be noted that the preset valve opening pressure P of the fourth electronically controlled valve 54 is 开 It can be calculated based on experimental measurements and corresponding calculation models and set in advance in the control module 7. The preset valve opening pressure of the compression system composed of different multi-stage compression cylinders 1 is different.

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

[0077] P 瓶max represents the maximum use pressure of the gas cylinder 31 currently filled in the gas storage device 3 (i.e., the target gas storage pressure of the gas cylinder 31, which is the set value), P进low It represents the lower limit of the intake pressure of the long tube trailer 8 which just does not need the final compression cylinder 12 to be put into 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 pistons of all compression cylinders in the multi-stage compression cylinder 1 and the inner wall of the cylinder barrel during the reciprocating motion of the compression cylinder, the hydraulic oil pressure loss pressure caused by the friction loss caused by overcoming the deadweight of the compression cylinder rod, the surface area of ​​the oil side working surface of the piston of the penultimate compression cylinder, and the surface area of ​​the gas side working surface of the piston 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 about 1 MPa.

[0078] The opening and closing of the fourth electrically controlled valve 54 is controlled according to the preset valve opening conditions of this embodiment, so that the timing of the final compression cylinder 12 entering and exiting the compression operation can be more accurately controlled, further improving the unloading efficiency of the gas unloading system.

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

[0080] It should be noted that, since there are two oil ports on the oil side of the final-stage compression cylinder 12, and the oil inlet and oil outlet states of the two oil ports are constantly switched to control the reversing compression of the compression cylinder, 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 electric control valve 54, the oil circuit of the final-stage compression cylinder 12 is cut off. Therefore, the fourth electric control valve 54 can be installed at any oil port of the final-stage compression cylinder 12. However, when the fourth electric control valve 54 is installed at only one oil port, and when the fourth electric control valve 54 is closed, the oil port where the fourth electric control valve 54 is installed is the oil outlet, a small amount of oil will enter the final-stage compression cylinder 12 under the action of the hydraulic oil pressure. Therefore, in order to ensure a better cutting effect, in this embodiment, two fourth electric control valves 54 are preferably used, that is, two fourth electric control valves 54 respectively control the on-off of the two oil ports of the final-stage compression cylinder 12. In order to ensure the synchronization of the cut-off signals of the two fourth electrically-controlled valves 54, the two fourth electrically-controlled valves 54 are communicatively connected to the same signal output terminal of the control module 7. In this way, the two fourth electrically-controlled valves 54 can be simultaneously controlled to open and close synchronously by the same control signal output from the same signal output terminal of the control module 7, thereby reducing the waste of the control port of the control module 7.

[0081] In one embodiment, the gas outlets of the plurality of gas storage bottles 31 are also connected to the gas inlet of the first-stage compression cylinder 11 through their respective corresponding low-pressure gas recovery pipelines;

[0082] Correspondingly, the electrically controlled valve group 5 further includes a fifth electrically controlled valve 55 arranged on each low-pressure gas recovery pipeline.

[0083] By setting a low-pressure gas recovery pipeline to connect the gas outlet of the gas cylinder 31 with the gas inlet of the first-stage compression cylinder 11, and setting a fifth electrically-controlled valve 55 on the low-pressure gas recovery pipeline, when the gas pressure in the gas cylinder 31 in the gas storage device 3 is low and cannot meet the holiday demand of the gas filling machine 4, the fifth electrically-controlled valve 55 on the corresponding gas cylinder 31 is controlled to open, and the gas in the gas cylinder 31 is compressed and pressurized by the same set of multi-stage compression cylinders 1 used for unloading gas and then stored in other gas cylinders 31 of the gas storage device 3, thereby completing the transfer and compression of the gas in the low-pressure gas cylinder 31, improving the gas utilization rate, and when the gas pressure of each gas cylinder 31 in the gas storage device 3 is insufficient and cannot supply gas to the gas filling machine 4 and there is no long tube trailer 8 to supply gas to the gas filling machine 4, the low-pressure gas recovery and pressurization are realized by adopting this structure, so that emergency gas supply to the gas filling machine 4 can be realized.

[0084] In one embodiment, one end of the air inlet pipeline close to the air outlet is further connected to the air inlet of the gas filling machine 4 through a gas filling branch pipe. In this way, the gas output by the long tube trailer 8 can directly supply gas to the gas filling machine 4 through the air inlet pipeline and the gas filling branch pipe, so that when the gas storage device 3 in the gas filling station is full but the gas of the long tube trailer 8 has not been unloaded, the long tube trailer 8 can directly supply gas to the gas filling machine 4 to further unload the gas from the long tube trailer 8.

[0085] In one embodiment, the gas-filling branch pipes and the gas outlets of each gas-filling pipeline are integrated into a gas-filling main pipe, and the gas outlet of the gas-filling main pipe is connected to the gas outlet of the gas-filling machine 4. Since the gas-filling machine 4 has only one gas inlet, the gas-filling branch pipes and the gas outlets of each gas-filling pipeline are integrated into a gas-filling main pipe, and the gas outlet of the gas-filling main pipe is connected to the gas outlet of the gas-filling machine 4, so that the pipeline arrangement inside the gas-filling machine 4 can be reduced.

[0086] In one embodiment, a gas cooler 9 is provided on the pipeline of the gas outlet of each compression cylinder in the multi-stage compression cylinder 1, and the gas cooler 9 is used to cool down the gas discharged from the corresponding compression cylinder. By providing the gas cooler 9 on the pipeline of the gas outlet of each compression cylinder in the multi-stage compression cylinder 1, during the gas unloading process of the long tube trailer 8, the compressed gas output by the corresponding compression cylinder is cooled by each gas cooler 9, thereby increasing the gas density, so that the gas storage cylinder 31 can store more gas under the same gas pressure, and further improve the gas unloading rate of the long tube trailer 8.

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

[0088] When the long tube trailer 8 is unloading gas, the control module 7 controls the fixed frequency electrical start-up, 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 is compressed and reversed 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, and the target gas storage pressure of the high-pressure gas cylinder 31 is lower than the target gas storage pressure of the medium-pressure gas cylinder 31. When the tube trailer 8 is unloaded, the high-pressure gas cylinder 31 is first filled, and when the gas pressure of the tube trailer 8 does not reach the gas pressure for filling the high-pressure gas cylinder 31, the medium-pressure gas cylinder 31 is filled, so that the gas unloading rate of the tube trailer 8 is improved by adding the medium-pressure gas cylinder 31 and changing the corresponding gas unloading control logic on the basis of the existing technology.

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

[0091] S1, when the system power supply is started, control the gas station unloading system to enter the standby state;

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

[0093] S3, according to the real-time gas storage pressure P of each gas storage cylinder of the gas storage device 瓶 Determine whether the preset gas unloading condition is currently met. If so, execute S4; if not, jump to S1;

[0094] Specifically, in this embodiment, satisfying the preset gas unloading condition means that the pressure of the gas cylinder with the highest target gas storage pressure among the gas cylinders in the gas storage device is lower than the starting pressure setting value of the gas unloading system. For CNG, the starting pressure setting value is usually 21MPa, and for hydrogen, the starting pressure setting value is usually 38MPa.

[0095] S4, controlling the fourth electronically controlled valve to open, and controlling the second electronically controlled valves on each gas storage pipeline to operate according to a preset gas filling control strategy, so as to fill each gas storage cylinder of the gas storage device in order from high to low according to the target gas storage pressure;

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

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

[0098] S6, according to the intake pressure P of the second-to-last compression cylinder 进 and the real-time gas storage pressure P of the currently filled gas cylinder 瓶 To control the opening and closing state of the fourth electric control valve, so that the last stage compression cylinder starts compression cylinder operation or quits compression operation, and in the multi-stage compression cylinder operation process, S7 and S8 are executed in parallel;

[0099] Specifically, according to the intake pressure P of the penultimate compression cylinder 进 and the real-time gas storage pressure P of the currently filled gas cylinder 瓶 The specific process of controlling the opening and closing state of the fourth electric control valve is as follows:

[0100] Determine the intake pressure P 进 and real-time gas storage pressure P 瓶 Whether the preset valve opening conditions are met,

[0101] If the conditions are met, the first control instruction is output to control the fourth electronically controlled valve to open, connect the oil circuit of the final compression cylinder, and put the final compression cylinder into compression operation;

[0102] If it is not satisfied, the second control instruction is output to control the fourth electric control valve to close, disconnect the oil circuit of the final compression cylinder, and make the final compression cylinder quit compression work.

[0103] Among them, the preset valve opening conditions are as follows:

[0104] P 瓶 -P进 ≥P 开

[0105] Among them, P 开 Indicates the preset valve opening pressure of the fourth electronically controlled valve.

[0106] It should be noted that the preset valve opening pressure P of the fourth electronically controlled valve is 开 It can be calculated based on experimental measurements and corresponding calculation models and set in advance in the control module. The preset valve opening pressure of the compression system composed of different multi-stage compression cylinders is different.

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

[0108] P 瓶max Indicates 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 the set value), P 进low It indicates the lower limit of the intake pressure of the long tube trailer that just does not need the final compression cylinder to be put into compression work (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 pistons of all compression cylinders in the multi-stage compression cylinder and the inner wall of the cylinder barrel during the reciprocating motion of the compression cylinder, the hydraulic oil pressure loss pressure caused by the friction loss caused by overcoming the deadweight of the compression cylinder rod, the surface area of ​​the oil-side working surface of the piston of the second-to-last compression cylinder, and the surface area of ​​the gas-side working surface of the piston of the second-to-last compression cylinder). The pressure margin is a set value set according to the specific situation and / or experience when debugging the equipment, generally around 1MPa.

[0109] The opening and closing of the fourth electrically controlled valve is controlled according to the preset valve opening conditions of this embodiment, so that the timing of the final stage compression cylinder entering compression work and exiting compression work can be controlled more accurately, further improving the gas unloading efficiency of the gas unloading system.

[0110] S7, judging whether the preset standby condition is met, if yes, jumping to S1, if no, jumping to S5;

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

[0112] S8, judging whether the long tube trailer has been completely unloaded, if so, replacing the long tube trailer and jumping to S1, if not, jumping to S5.

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

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

[0115] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0116] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0117] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, software modules executed by a processor, or a combination of the two. The software modules may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a 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 implement or use the present application. Various modifications to these embodiments will be 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 the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gas unloading system for a gas filling station, characterized in that: It includes a multi-stage compression cylinder, a fixed displacement hydraulic drive system, a gas storage device, a gas dispenser, an electric control valve group, an air pressure detection unit and a control module, wherein the hydraulic drive system, the gas dispenser, the electric control valve group and the air pressure detection unit are respectively connected to the control module in communication, wherein: The gas storage device comprises a plurality of gas storage cylinders with different target gas storage pressures; The multi-stage compression cylinder comprises a plurality of compression cylinders connected in series from the first stage to the last stage through an air transmission pipeline, the air inlet of the first stage compression cylinder in the multi-stage compression cylinder is connected to the long tube trailer through the air inlet pipeline, and the air outlet of the last stage compression cylinder in the multi-stage compression cylinder is connected to the air inlet of the air outlet pipeline; The gas inlets of the multiple gas cylinders are connected to the gas outlets of the gas outlet pipelines through their corresponding gas storage pipelines, and the gas outlets of the multiple gas cylinders are connected to the gas inlet of the gas dispenser through their corresponding gas filling pipelines; The hydraulic drive system is connected to the oil inlet / outlet and the oil outlet / inlet of each compression cylinder in the multi-stage compression cylinder through a hydraulic pipeline; The electrically controlled valve group includes a first electrically controlled valve arranged at one end of the air inlet of the air inlet pipeline, a second electrically controlled valve arranged on each air storage pipeline, a third electrically controlled valve arranged on each air filling pipeline, and a fourth electrically controlled valve arranged on at least one oil port of the final stage compression cylinder; The air pressure detection unit includes a pressure sensor disposed at the air inlet of the penultimate compression cylinder for detecting the air inlet pressure P of the penultimate compression cylinder. 进 The intake pressure sensor and the real-time gas storage pressure P of each gas storage cylinder are arranged on each gas storage cylinder to detect the real-time gas storage pressure P of each gas storage cylinder. 瓶 Gas storage pressure sensor; The control module is configured to control the operation of the second electric control valve on each gas storage pipeline according to a preset gas charging control strategy, so as to fill each gas storage cylinder of the gas storage device in order from high to low according to the target gas storage pressure, and according to the intake pressure P of the second-to-last compression cylinder. 进 and the real-time gas storage pressure P of the currently filled gas cylinder 瓶 To control the opening and closing state of the fourth electric control valve, so that the final stage compression cylinder is put into compression cylinder operation or exits compression operation.

2. The gas unloading system of a gas filling station according to claim 1, characterized in that: The inlet pressure P of the second-to-last compression cylinder 进 and the real-time gas storage 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 Whether the preset valve opening conditions are met, If the conditions are met, the first control instruction is output to control the fourth electric control valve to open, connect the oil circuit of the final compression cylinder, and put the final compression cylinder into compression operation; If it is not satisfied, the second control instruction is output to control the fourth electric control valve to close, disconnect the oil circuit of the final compression cylinder, and make the final compression cylinder quit compression work. Wherein, the preset valve opening conditions are as follows: P 瓶 -P 进 ≥P 开 Among them, P 开 Indicates the preset valve opening pressure of the fourth electrically controlled valve.

3. The gas unloading system of a gas filling station according to claim 1 or 2, characterized in that: There are two fourth electrically controlled valves, which are respectively mounted on the oil inlet / outlet and the oil outlet / inlet of the final compression cylinder, and the two fourth electrically controlled valves are communicatively connected to the same signal output terminal of the control module.

4. The gas unloading system of a gas filling station according to claim 1, characterized in that: The gas outlets of the plurality of gas storage cylinders are also connected to the gas inlet of the first-stage compression cylinder through their corresponding low-pressure gas recovery pipelines; Correspondingly, the electrically-controlled valve group further includes a fifth electrically-controlled valve arranged on each low-pressure gas recovery pipeline.

5. The gas unloading system of a gas filling station according to claim 1, 2 or 4, characterized in that: One end of the air inlet pipeline close to its air outlet is also connected to the air inlet of the gas filling machine through a gas filling branch pipe.

6. The gas unloading system of a gas filling station according to claim 5, characterized in that: The gas filling branch pipes and the gas outlets of each gas filling pipeline are collected into a gas filling main pipe, and the gas outlet of the gas filling main pipe is connected to the gas outlet of the gas filling machine.

7. The gas unloading system of a gas filling station according to claim 1, 2, 4 or 6, characterized in that: A gas cooler is provided on the pipeline of the gas outlet of each stage of the multi-stage compression cylinder, and the gas cooler is used to cool down the gas discharged from the corresponding compression cylinder.

8. The gas unloading system of a gas filling station according to claim 1, 2, 4 or 6, characterized in that: The hydraulic drive system includes a hydraulic oil tank, a quantitative booster pump, a fixed-frequency motor and a hydraulic reversing valve. The output shaft of the fixed-frequency motor is drivingly connected to the quantitative booster pump. The oil inlet of the quantitative booster pump is connected to the hydraulic oil tank through an oil inlet pipeline. The oil outlet of the quantitative booster pump is connected to the oil inlet of the hydraulic reversing valve through an oil injection pipeline. The oil outlet of the hydraulic reversing valve is connected to the hydraulic oil tank through an oil return pipeline. The two working oil ports of the hydraulic reversing valve are respectively connected to the oil inlet / outlet and oil outlet / inlet of each compression cylinder in the multi-stage compression cylinder through hydraulic pipelines.

9. The gas unloading system of a gas filling station according to claim 1, 2, 4 or 6, characterized in that: The gas storage device comprises a high-pressure gas storage cylinder and a medium-pressure gas storage cylinder, and a target gas storage pressure of the high-pressure gas storage cylinder is lower than a target gas storage pressure of the medium-pressure gas storage cylinder.

10. A control method for a gas filling station gas unloading system according to any one of claims 1 to 9, characterized in that: The steps include: S1, when the system power supply is started, controlling the gas station unloading system to enter a standby state; S2, obtaining the real-time gas storage pressure P of each gas storage cylinder of the gas storage device 瓶 ; S3, according to the real-time gas storage pressure P of each gas storage cylinder of the gas storage device 瓶 Determine whether the preset gas unloading condition is currently met. If so, execute S4; if not, jump to S1; S4, controlling the fourth electronically controlled valve to open, and controlling the second electronically controlled valves on each gas storage pipeline to operate according to a preset gas filling control strategy, so as to fill each gas storage cylinder of the gas storage device in order from high to low according to the target gas storage pressure; S5, obtaining the intake pressure P of the penultimate compression cylinder 进 ; S6, according to the intake pressure P of the second-to-last compression cylinder 进 and the real-time gas storage pressure P of the currently filled gas cylinder 瓶 to control the opening and closing state of the fourth electric control valve, so that the last stage compression cylinder starts compression cylinder operation or quits compression operation, and in the operation process of the multi-stage compression cylinder, S7 and S8 are executed in parallel; S7, judging whether the preset standby condition is met, if yes, jumping to S1, if no, jumping to S5; S8, judging whether the long tube trailer has been completely unloaded, if so, replacing the long tube trailer and jumping to S1, if not, jumping to S5.

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