Flow adjusting method for diaphragm compressor

Abstract

The invention relates to the technical field of diaphragm compressors, in particular to a diaphragm compressor flow adjusting method. The method specifically comprises the steps that an oil side film cavity is connected with liquid storage device oil cavities of a plurality of liquid storage devices through pipelines; delta qv is calculated; the required regulation and control flow of the diaphragm compressor is calculated; the flow needing to be regulated and controlled is compared with delta qv of the liquid storage device, and a control valve, matched with the flow needing to be regulated and controlled of the diaphragm compressor, of the liquid storage device is opened; after the diaphragm compressor is adjusted to work stably, the actual flow of the diaphragm compressor is obtained; and when the actual flow of the diaphragm compressor meets the condition that q is larger than or equal to (1-lambda) qg and smaller than or equal to (1 + lambda) qg, the adjusting procedure is terminated. By adjusting the flow of a certain stage of the diaphragm compressor for the hydrogen refueling station, the problems of insufficient pressurizing capacity, unbalanced pressure ratio distribution and poor working condition adaptability caused by pressure ratio change of the diaphragm compressor in an application scene of an existing hydrogen refueling station are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of diaphragm compressors, and particularly to a flow regulation method for a diaphragm compressor. Background Art

[0002] Hydrogen energy is a secondary energy source with great potential, which can provide power for hydrogen fuel cell vehicles and is an important part of clean energy. Hydrogen refueling stations are key infrastructure in the application of hydrogen energy, which can supply hydrogen efficiently and cleanly, support the rapid hydrogen refueling of fuel cell vehicles, and promote the utilization of renewable energy and environmental protection. Diaphragm compressors are crucial in hydrogen refueling stations. Due to their excellent sealing performance and high gas cleanliness, they effectively improve the compression efficiency of hydrogen. In the high-pressure environment of hydrogen refueling stations, diaphragm compressors boost hydrogen from low pressure to the required high pressure, ensuring a stable and safe hydrogen supply for fuel cell vehicles. Especially during the filling process of hydrogen in a 70 MPa hydrogen refueling station, diaphragm compressors are widely popular due to their durability, high efficiency, and safety, supporting the efficient operation of hydrogen refueling stations. Considering safety, the application of externally supplied hydrogen refueling stations is becoming increasingly common, and it has also become a common method for long tube trailers to supply gas to the hydrogen storage tanks in hydrogen refueling stations. Since the pressure of the long tube trailer is relatively low after filling, a two-stage diaphragm compressor is required for pressurization during the filling process.

[0003] The existing application scenarios of hydrogen refueling stations are typical variable-condition operations. During the hydrogen filling process, the hydrogen pressure in the long tube trailer continuously decreases, while the pressure in the hydrogen storage tank continuously increases, resulting in continuous changes in the total pressure ratio of the two-stage diaphragm compressor. During the pressurization stage, the first-stage pressure ratio of the diaphragm compressor is limited by the effective suction volume ratio of the two-stage compressors, and the change range is very small, while the second-stage pressure ratio is affected by the working conditions and changes greatly. Since the first-stage pressure ratio is not adjustable, this limits its pressurization ability, causing the hydrogen in the long tube trailer to not be able to drop to the required pressure, reducing economic benefits. At the same time, due to the fact that the first-stage pressure ratio is much smaller than the second-stage pressure ratio under the condition of high-pressure ratio operation of the diaphragm compressor, the distribution of the first and second-stage pressure ratios during the actual operation of the compressor is unbalanced, deviating far from the design point, reducing the efficiency and stability of the compressor. Summary of the Invention

[0004] In order to solve the problems of insufficient pressurization ability, unbalanced pressure ratio distribution, and poor working condition adaptability existing in diaphragm compressors in the existing application scenarios of hydrogen refueling stations, the present invention provides a flow regulation method for a diaphragm compressor.

[0005] The present invention realizes the re-distribution of the first and second-stage pressure ratios by adjusting the flow rate of a certain stage of the diaphragm compressor, thereby ensuring that the diaphragm compressor is always in a stable, efficient, and safe operating state under typical variable conditions in hydrogen refueling stations.

[0006] To achieve the above object, the technical solution of the present invention is as follows.

[0007] The present invention provides a diaphragm compressor flow regulation method, which is applied to a diaphragm compressor. The diaphragm compressor includes a diaphragm head structure, and the diaphragm head structure has an oil-side diaphragm cavity. The specific method includes the following steps:

[0008] The oil-side diaphragm cavity is connected to a plurality of liquid reservoirs through pipelines; each of the liquid reservoirs has a liquid reservoir oil cavity, and the outlet of each liquid reservoir oil cavity is provided with a control valve; the volume of the hydraulic oil entering the oil-side diaphragm cavity in each liquid reservoir oil cavity when the diaphragm compressor ends suction and the volume of the hydraulic oil expanded in the oil-side diaphragm cavity are obtained to calculate the adjustable flow rate of each liquid reservoir in the working cycle of the diaphragm compressor.

[0009] Obtain the required control flow of the diaphragm compressor; compare the required control flow of the diaphragm compressor with the available control flow of each liquid reservoir in the working cycle of the diaphragm compressor, and open the control valve of the liquid reservoir that matches the required control flow of the diaphragm compressor.

[0010] After the diaphragm compressor is adjusted to work stably, the actual flow of the diaphragm compressor is obtained; when the actual flow of the diaphragm compressor meets the following conditions, the adjustment program is terminated:

[0011] (1-λ)q g ≤q≤(1+λ)q g ; where λ is the control margin factor, q g is the target flow rate of the diaphragm compressor, and q is the actual flow rate of the diaphragm compressor.

[0012] In view of the shortcomings of the existing diaphragm compressor flow regulation technology, the present invention provides a new solution for regulating the flow of diaphragm compressors based on the unique oil overflow and oil replenishment mechanism of diaphragm compressors and the compressibility of hydraulic oil. By adjusting the flow of a certain level of diaphragm compressors, the redistribution of the primary and secondary pressure ratios is achieved, thereby ensuring that the diaphragm compressor is always in a stable, efficient and safe operating state under the typical variable working conditions of hydrogen stations. The present invention mainly realizes stepless regulation of the flow of diaphragm compressors by increasing the number of liquid storage devices with different volumes in parallel, and the energy loss is small during flow regulation, which will not affect the stability of the system and will not have a negative impact on the life of the compressor.

[0013] Preferably, 0.1<λ<0.15.

[0014] Preferably, when the actual flow rate of the diaphragm compressor does not satisfy (1-λ)q g ≤q≤(1+λ)q g If the condition is met, the following steps are performed:

[0015] When q<(1-λ)q gWhen the flow rate of the diaphragm compressor is regulated, the control valve of the liquid storage device that matches the required regulated flow rate of the diaphragm compressor is closed, and the control valve of the liquid storage device that is close to the required regulated flow rate of the diaphragm compressor is opened;

[0016] Return to the step of obtaining the actual flow rate of the diaphragm compressor after the diaphragm compressor is adjusted to work stably, until the actual flow rate of the diaphragm compressor satisfies (1-λ)q g ≤q≤(1+λ)q g After the condition is met, the adjustment procedure is terminated.

[0017] Preferably, when the actual flow rate of the diaphragm compressor does not satisfy (1-λ)q g ≤q≤(1+λ)q g If the condition is met, the following steps are performed:

[0018] When q>(1+λ)q g , return to the step of calculating the required control flow of the diaphragm compressor, and at the same time, compare the calculated required control flow of the diaphragm compressor with the available control flow of each liquid reservoir in the working cycle of the diaphragm compressor until the actual flow of the diaphragm compressor satisfies (1-λ)q g ≤q≤(1+λ)q g After the conditions are met, the control valve of the liquid reservoir matching the required regulating flow of the diaphragm compressor is opened and the regulating procedure is terminated.

[0019] Preferably, the calculation formula for the adjustable flow rate of a liquid reservoir in the working cycle of the diaphragm compressor is as follows:

[0020] Δq v =(Δv oil +Δv oil-e ) T λ p λ v-e n;

[0021] Among them, Δq v Indicates the adjustable flow rate of a liquid reservoir in the working cycle of the diaphragm compressor; Δv oil Indicates the volume of hydraulic oil in a reservoir oil chamber entering the oil side diaphragm chamber when the diaphragm compressor ends suction; Δv oil-e Indicates the volume of the hydraulic oil expanded in the oil-side diaphragm chamber when the diaphragm compressor is finished sucking air; T Indicates the temperature coefficient caused by the intake air heating of the diaphragm compressor; λ p is the pressure coefficient caused by the resistance loss of the diaphragm compressor; v-e is the gas expansion coefficient caused by the clearance volume of the diaphragm compressor; n is the rotation speed of the diaphragm compressor.

[0022] Preferably, each of the liquid reservoirs has a liquid reservoir air cavity; the method for obtaining the volume of hydraulic oil in a liquid reservoir oil cavity entering the oil-side diaphragm cavity when the diaphragm compressor ends suction is as follows:

[0023] Obtain the volume of the reservoir cavity, the overflow oil pressure of the diaphragm compressor, and the oil pressure at the end of the diaphragm compressor suction to calculate the volume of the hydraulic oil in a reservoir oil cavity entering the oil side diaphragm cavity at the end of the diaphragm compressor suction, recorded as Δv oil . Δv oil The calculation formula is as follows:

[0024] Where Δv oil It indicates the volume of hydraulic oil in a reservoir oil chamber entering the oil side diaphragm chamber when the diaphragm compressor ends suction; v o Indicates the volume of the air chamber of the liquid reservoir; p 0 Indicates the overflow oil pressure of the diaphragm compressor; p 1 Indicates the oil pressure at the end of suction of the diaphragm compressor; m represents the process index.

[0025] Preferably, the method for obtaining the expanded volume of the hydraulic oil in the oil-side diaphragm chamber when the diaphragm compressor ends suction is as follows:

[0026] Obtain the overflow oil pressure of the diaphragm compressor, the oil pressure at the end of the diaphragm compressor suction, and the total volume of all hydraulic oil in the oil-side diaphragm chamber and the reservoir oil chamber connected to the oil-side diaphragm chamber at the end of the diaphragm compressor exhaust. Calculate the volume of the hydraulic oil expansion in the oil-side diaphragm chamber at the end of the diaphragm compressor suction, recorded as Δv oil-e ; Δv oil-e The calculation formula is as follows:

[0027] Where Δv oil-e It indicates the volume of the hydraulic oil expanded in the oil-side diaphragm chamber when the diaphragm compressor is finished sucking air; p 0 Indicates the overflow oil pressure of the diaphragm compressor; p 1 Indicates the oil pressure at the end of the diaphragm compressor suction; β indicates the bulk elastic modulus of the hydraulic oil; v oil-tdc It indicates the total volume of all hydraulic oil in the oil-side diaphragm chamber and the reservoir oil chamber connected to the oil-side diaphragm chamber when the diaphragm compressor is exhausted.

[0028] Preferably, the liquid reservoir includes a liquid reservoir shell, a floating piston and a liquid reservoir end cover; the liquid reservoir end cover is fixedly connected to the liquid reservoir shell and is used to seal the liquid reservoir shell; the floating piston is slidably configured in the liquid reservoir shell and is configured to separate the internal space of the liquid reservoir shell and the liquid reservoir end cover to form a liquid reservoir oil chamber and a liquid reservoir air chamber.

[0029] Preferably, the oil chamber of the liquid reservoir has an oil circuit, and the control valve of the liquid reservoir is arranged on the corresponding oil circuit; the air chamber of the liquid reservoir is arranged with an end cover air suction pipeline, and the end cover air suction pipeline is arranged with an end cover air suction valve.

[0030] Preferably, the liquid reservoir end cover is fixed to the liquid reservoir shell via a second connecting piece; and the end cover air intake pipeline is fixed to the liquid reservoir end cover via a third connecting piece.

[0031] Preferably, the diaphragm compressor also includes a control system, which includes a PLC control module, an oil pressure sensor and a flow meter; the flow meter is connected to the exhaust pipeline of the diaphragm compressor; the oil pressure sensor is connected to the oil side diaphragm chamber of the diaphragm compressor; the PLC control module is respectively connected to the oil pressure sensor and the flow meter as well as the control valve signal of the liquid storage device.

[0032] Beneficial effects of the present invention:

[0033] 1. The present invention provides a new solution for regulating the flow rate of a diaphragm compressor based on the unique oil overflow and oil replenishment mechanism of the diaphragm compressor and the compressibility of the hydraulic oil. The present invention can effectively regulate the flow rate of the diaphragm compressor, and by adjusting the flow rate of a certain level of the diaphragm compressor, the primary and secondary pressure ratios can be redistributed, thereby ensuring that the diaphragm compressor is always in a stable, efficient and safe operating state under the typical variable working conditions of the hydrogenation station. The method of the present invention can improve the compressor's boosting capacity, efficiency and stability, thereby improving the economic benefits and operational reliability of the hydrogenation station.

[0034] 2. The present invention realizes stepless regulation of the flow rate of the diaphragm compressor by increasing the number of liquid storage devices with different volumes in parallel, and the energy loss is small during the flow rate regulation, which will not affect the stability of the system and will not have a negative impact on the life of the compressor.

[0035] 3. The present invention has a simple structure, convenient installation and low cost, and can show good performance and high operability during the flow regulation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the diaphragm compressor diaphragm head structure.

[0037] Figure 2 It is a structural schematic diagram of the liquid storage device.

[0038] Figure 3 This is a state diagram of the flow control system when the air intake is completed when the control valve is not opened in one embodiment of the present invention.

[0039] Figure 4 This is a state diagram of the flow control system when the control valve is opened and the air intake is completed in one embodiment of the present invention.

[0040] Figure 5 It is a schematic diagram of a flow regulation system with three liquid reservoirs connected in parallel in one embodiment of the present invention.

[0041] Description of reference numerals:

[0042] 10. Die head structure; 101. Air side membrane head; 102. Diaphragm head exhaust valve; 103. Diaphragm head suction valve; 104. Air distribution plate; 105. Diaphragm; 106. Oil distribution plate; 107. Oil side membrane head; 108. Diaphragm head piston; 109. First connecting piece; 110. Air side membrane cavity; 111. Oil side membrane cavity; 112. Oil overflow hole; 113. Oil replenishing hole.

[0043] 20. Liquid reservoir; 201. Liquid reservoir housing; 202. Floating piston; 203. Liquid reservoir end cover; 204. End cover air suction valve; 205. End cover air suction pipeline; 206. Second connecting piece; 207. Third connecting piece; 208. Liquid reservoir air cavity; 209. Liquid reservoir oil cavity; 210. Sealing piece; 211. Oil circuit.

[0044] 30. Control system; 301. PLC control module; 302. Oil pressure sensor; 303. Flow meter. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0047] The diaphragm compressor is a specially designed volumetric compression device that compresses and transports gas mainly through the reciprocating deformation of the diaphragm in the cylinder. Due to its unique structure and working principle, including high compression ratio and excellent sealing performance, it can effectively prevent hydraulic oil and solid impurities from contaminating the compressed gas, making it widely used in hydrogen refueling stations.

[0048] like Figure 1 The diaphragm head structure of the diaphragm compressor includes an air side diaphragm head 101, a diaphragm head exhaust valve 102, a diaphragm head suction valve 103, an air distribution plate 104, a diaphragm 105, an oil distribution plate 106, an oil side diaphragm head 107, a diaphragm head piston 108 and a first connecting piece 109.

[0049] The air side diaphragm head 101 and the oil side diaphragm head 107 are fixedly connected by a first connecting member 109; the air side diaphragm head 101 and the oil side diaphragm head 107 are combined to form a mounting cavity; the gas distribution plate 104, the diaphragm 105 and the oil distribution plate 106 are arranged in the mounting cavity, and the diaphragm 105 is arranged between the gas distribution plate 104 and the oil distribution plate 106. Specifically, the first connecting member 109 is a cylinder head connecting stud.

[0050] As the first connecting member 109 gradually presses the air-side diaphragm head 101 and the oil-side diaphragm head 107, the two ends of the air distribution plate 104 and the oil distribution plate 106 are tightly matched to press and fix the diaphragm 105, so that the diaphragm 105 is fixed between the air distribution plate 104 and the oil distribution plate 106; at this time, the diaphragm 105 separates the inner cavity enclosed by the air distribution plate 104 and the oil distribution plate 106 to form an air-side diaphragm cavity 110 and an oil-side diaphragm cavity 111; the air-side diaphragm cavity 110 is arranged on the side close to the air distribution plate 104; the oil-side diaphragm cavity 111 is arranged on the side close to the oil distribution plate 106. Specifically, the space enclosed by the diaphragm 105 and the air distribution plate 104 is the air-side diaphragm cavity 110, and the space enclosed by the diaphragm 105 and the oil distribution plate 106 is the oil-side diaphragm cavity 111.

[0051] Specifically, one side of the air-side membrane head 101 has a first trough body, and the gas distribution disk 104 is arranged on one side of the first trough body; one side of the oil-side membrane head 107 has a second trough body, and the oil distribution disk 106 is arranged on one side of the second trough body. The air-side membrane head 101 and the gas distribution disk 104 are provided with connected exhaust holes and air intake holes, and one end of the exhaust hole and the air intake hole are both connected to the air-side membrane cavity 110; the exhaust hole is provided with a membrane head exhaust valve 102 at one end of the gas distribution disk 104; the air intake hole is provided with a membrane head air intake valve 103 at one end of the gas distribution disk 104. The membrane head exhaust valve 102 is a one-way exhaust valve; the membrane head air intake valve 103 is a one-way air intake valve. The membrane head exhaust valve 102 and the membrane head air intake valve 103 are used to control the one-way exhaust and one-way air intake of the air-side membrane cavity 110. Among them, the exhaust hole is externally connected to the membrane head exhaust pipeline; the air intake hole is externally connected to the membrane head air intake pipeline.

[0052] Specifically, the space enclosed by the oil distribution plate 106 and the oil side diaphragm head 107 is a buffer chamber, which can be regarded as a part of the oil side diaphragm chamber; the oil distribution plate 106 has a plurality of channels, and the buffer chamber is connected to the oil side diaphragm chamber 111 through the plurality of channels; the oil side diaphragm head 107 has a piston hole, and a diaphragm head piston 108 is arranged in the piston hole; the side edge of the oil side diaphragm head 107 has an oil overflow hole 112, and the oil overflow hole 112 is arranged with an oil overflow valve; the oil pressure in the oil side diaphragm chamber 111 is controlled by the oil overflow valve. Specifically, the side edge of the oil side diaphragm head 107 away from the oil overflow hole 112 has an oil replenishment hole 113, and the oil replenishment is carried out through the oil replenishment hole 113 and an external oil replenishment pipeline. Specifically, the diaphragm head piston 108 is externally connected to a crank connecting rod mechanism, and the crank connecting rod mechanism is connected to an external motor, and the crank connecting rod mechanism is driven by the external motor to drive the diaphragm head piston 108 to move. The crank-connecting rod mechanism is a prior art, which is mainly driven by an external motor to drive the membrane head piston 108 to move. The specific structure will not be described in detail here.

[0053] The working principle of the diaphragm compressor's diaphragm head structure is as follows:

[0054] The diaphragm compressor drives the crank-connecting rod mechanism through an external motor, thereby pushing the diaphragm head piston 108 to move. When the diaphragm head piston 108 reaches the top dead center, the diaphragm 105 is deformed toward the gas side diaphragm cavity 110 due to the extrusion of the hydraulic oil, so that the space of the gas side diaphragm cavity 110 is reduced, and the gas is compressed and discharged. During the entire gas compression process, the hydraulic oil pressure increases synchronously with the gas pressure. When the diaphragm 105 is close to the surface of the gas distribution disk 104 on one side of the gas side diaphragm head 101, the gas discharge ends, and the diaphragm head piston 108 reaches the top dead center. At this time, the hydraulic oil pressure reaches the set maximum oil overflow pressure, and the excess hydraulic oil is discharged through the oil overflow valve.

[0055] Subsequently, the diaphragm piston 108 starts to move toward the bottom dead center, the diaphragm 105 gradually returns to the equilibrium position, the space of the gas side diaphragm cavity 110 increases, and the residual gas begins to expand. When the gas pressure in the gas side diaphragm cavity 110 is lower than the gas pressure in the air inlet pipe, the diaphragm head suction valve 103 opens and the suction process begins.

[0056] During the gas expansion and suction process of the entire diaphragm compressor, the hydraulic oil pressure and the gas pressure change in coordination. When the diaphragm head piston 108 reaches the lower dead center, the suction process ends. The diaphragm compressor has leakage during operation, and excess hydraulic oil is discharged from the overflow valve during exhaust. The amount of hydraulic oil discharged from the overflow valve is basically equal to the amount of oil replenishment.

[0057] At present, diaphragm compressors in existing hydrogen refueling station application scenarios have problems such as insufficient boosting capacity due to pressure ratio changes, unbalanced pressure ratio distribution, and poor adaptability to working conditions.

[0058] Regarding the problem of insufficient boosting capacity due to pressure ratio changes: During the hydrogen filling process, the total pressure ratio of the two-stage diaphragm compressor keeps changing due to the continuous decrease in the hydrogen pressure in the long-tube trailer and the continuous increase in the pressure in the hydrogen storage tank. The first-stage pressure ratio is limited by the effective suction volume ratio of the two-stage compressor, and the change range is small and cannot be adjusted, resulting in limited boosting capacity during the boosting stage, and the hydrogen in the long-tube trailer cannot be reduced to the required pressure, thereby reducing economic benefits.

[0059] Regarding the problem of imbalanced pressure ratio distribution: At present, when the diaphragm compressor is operating at a high pressure ratio, the first-stage pressure ratio is much smaller than the second-stage pressure ratio, resulting in an imbalanced pressure ratio distribution between the first and second stages. This imbalance causes the actual operating conditions of the compressor to deviate far from the design point, thereby reducing the efficiency and stability of the compressor.

[0060] Regarding the problem of poor adaptability to working conditions: Since the application scenario of hydrogen refueling stations is a typical variable working condition operation, the secondary pressure ratio is greatly affected by the working conditions, and the primary pressure ratio is not adjustable, resulting in the diaphragm compressor being unable to adapt well to the changes in working conditions. This not only affects the compressor's boosting effect and economic benefits, but may also have an adverse impact on the long-term stable operation of the compressor.

[0061] Since diaphragm compressors are widely used in hydrogenation stations, petrochemical and other industries, it is very important for diaphragm compressors to be able to cope with changes in flow, in order to adapt to changes in gas demand, ensure that the output of the diaphragm compressor matches the load, improve energy efficiency, and reduce energy waste. At the same time, flow regulation can extend the service life of the machine and keep the system pressure stable. Through flow regulation, diaphragm compressors can operate efficiently and stably under various working conditions.

[0062] At present, the main flow regulation methods of diaphragm compressors are bypass regulation and variable speed regulation. Bypass regulation is to set a bypass valve to connect the exhaust pipeline and the intake pipeline, and lead part of the compressed gas from the exhaust side of the diaphragm compressor back to the intake side, thereby reducing the effective flow of the diaphragm compressor and regulating the flow. Variable speed regulation is to control the speed of the diaphragm compressor drive motor to control the flow and achieve continuous regulation of the flow.

[0063] However, the main disadvantage of diaphragm compressor bypass flow regulation is the large energy loss. Due to the cyclic compression of bypass gas, the actual energy efficiency is reduced, which increases energy waste. In addition, bypass regulation may cause system pressure instability, especially in the case of large load changes, which may cause fluctuations in compressor operating efficiency, thereby affecting the stability of the entire system.

[0064] The main disadvantage of the diaphragm compressor's variable speed flow rate regulation is that the adjustable range is very narrow. Generally, the minimum frequency conversion is 30Hz, which means that the flow rate regulation range can only be between 60% and 100%. At the same time, the low speed operation of the diaphragm compressor will lead to insufficient lubrication of the moving parts, which will accelerate the wear of the moving parts and reduce the service life of the compressor. In addition, the continuous adjustment of the frequency converter has a great impact on the power grid, which is easy to cause vibration of the diaphragm compressor system.

[0065] In summary, diaphragm compressors face technical problems in flow regulation, such as energy loss, unstable system pressure, narrow adjustable range, insufficient lubrication of moving parts, and grid shock and vibration. These problems limit the performance and efficiency of diaphragm compressors and have an adverse impact on the stable operation and economic benefits of hydrogen refueling stations.

[0066] In view of the shortcomings of the existing diaphragm compressor flow regulation technology, the present invention provides a new solution for regulating the flow of diaphragm compressors based on the unique oil overflow and oil replenishment mechanism of the diaphragm compressor and the compressibility of hydraulic oil. The present invention can effectively regulate the flow of the diaphragm compressor. By adjusting the flow of a certain level of diaphragm compressor, the primary and secondary pressure ratios can be redistributed, thereby ensuring that the diaphragm compressor is always in a stable, efficient and safe operating state under the typical variable operating conditions of the hydrogen refueling station.

[0067] The method of the present invention can improve the boosting capacity, efficiency and stability of the compressor, thereby improving the economic benefits and operational reliability of the hydrogen refueling station.

[0068] The technical solution of the present invention is further described below through specific embodiments.

[0069] In the following examples, the methods described are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0070] The structure of the liquid storage device 20 is as follows: Figure 2 The reservoir 20 has a reservoir oil chamber 209, and the outlets of the reservoir oil chamber 209 are all equipped with control valves; the oil-side membrane chamber 111 is connected to a plurality of reservoir oil chambers 209 through pipelines.

[0071] In a preferred embodiment, Figure 2 The liquid reservoir 20 includes a liquid reservoir shell 201, a floating piston 202 and a liquid reservoir end cover 203; the liquid reservoir end cover 203 is fixedly connected to the liquid reservoir shell 201 for sealing the liquid reservoir shell 201; the floating piston 202 is slidably disposed in the liquid reservoir shell 201, and is configured to separate the internal space of the liquid reservoir shell 201 and the liquid reservoir end cover 203 into a liquid reservoir oil chamber 209 and a liquid reservoir air chamber 208.

[0072] Specifically, before the diaphragm compressor adjusts the flow rate, several reservoirs of different volumes can be connected in parallel. The different volumes of these reservoirs are designed to meet various flow requirements for flexible adjustment. When the compressor needs flow adjustment, the operator can selectively open the control valve to connect several reservoir oil chambers 209 with the diaphragm compressor oil side membrane chamber 111 for flow adjustment according to the calculated required control flow.

[0073] In a preferred embodiment, the reservoir oil chamber 209 has an oil circuit 211 , and the control valve is arranged on the corresponding oil circuit 211 ; the reservoir air chamber 208 is arranged with an end cover air suction pipeline 205 , and the end cover air suction pipeline 205 is arranged with an end cover air suction valve 204 .

[0074] Specifically, before the reservoir oil chamber 209 is connected to the diaphragm compressor oil side membrane chamber 111 through the control valve, the reservoir needs to store high pressure gas and hydraulic oil at a certain pressure through the end cover suction pipeline 205 and the oil circuit 211. Then, the reservoir oil chamber 209 is connected to the diaphragm compressor oil side membrane chamber 111 through the control valve to adjust the flow of the diaphragm compressor.

[0075] In a preferred embodiment, the reservoir end cover 203 is fixed to the reservoir housing 201 via a second connector 206 ; the end cover air intake pipeline 205 is fixed to the reservoir end cover 203 via a third connector 207 .

[0076] Specifically, the liquid reservoir shell 201 is connected to the liquid reservoir end cover 203 through the second connecting piece 206, and the connection between the liquid reservoir end cover 203 and the end cover air suction pipeline 205 is achieved by connecting the flange on the end cover air suction pipeline 205 and the third connecting piece 207 between the liquid reservoir end cover 203, and the end cover air suction valve 204 is installed by pressing the end cover air suction pipeline 205. The liquid reservoir end cover 203, the end cover air suction valve 204, the end cover air suction pipeline 205, the second connecting piece 206 and the third connecting piece 207 together constitute an end cover assembly.

[0077] Specifically, the reservoir housing 201 and the lower surface of the floating piston 202 form a reservoir oil chamber 209, and the reservoir housing 201 and the upper surface of the floating piston 202 and the reservoir end cover 203 form a reservoir air chamber 208. The floating piston 202 and the reservoir housing 201, and the reservoir end cover 203 and the reservoir housing 201 are sealed by sealing members 210, respectively.

[0078] Before the liquid reservoir 20 is connected to the oil side membrane chamber 111 of the diaphragm compressor, high pressure gas and hydraulic oil of a certain pressure are stored through the end cover suction pipeline 205 and the oil circuit 211. The oil chamber 209 of the liquid reservoir is connected to the oil side membrane chamber 111 of the diaphragm compressor through a control valve. Figure 3The diagram shows a state in which the control valve is not opened and the diaphragm compressor is at the end of suction, at which time the diaphragm 105 is in a balanced position.

[0079] During the expansion of gas, the oil pressure of the diaphragm compressor decreases synchronously with the gas pressure, and the diaphragm compressor overflows oil during the exhaust stage and replenishes oil during the intake stage. If the hydraulic oil leakage is not considered, the amount of oil replenished is equal to the amount of oil overflowed.

[0080] When the control valve connecting the oil side membrane chamber 111 of the diaphragm compressor and the reservoir oil chamber 209 is opened, the high pressure gas in the reservoir gas chamber 208 will push the floating piston 202 downward so that the volume of the reservoir oil chamber 209 is Δv oil The hydraulic oil flows into the oil side membrane chamber 111 of the diaphragm compressor through the connecting pipeline during the expansion and suction stages of the diaphragm compressor. At the same time, considering the compressibility of the hydraulic oil, the volume increment of the hydraulic oil in the oil side membrane chamber 111 of the diaphragm compressor after expansion is Δv oil-e .

[0081] like Figure 4 As shown, the increment of the volume of the hydraulic oil in the oil side diaphragm chamber 111 of the diaphragm compressor is Δv oil +Δv oil-e , so that the diaphragm 105 deforms upward at the end of suction, resulting in a decrease in the volume of the gas-side diaphragm chamber 110 and a decrease in the suction volume. During the compression phase of the diaphragm compressor, the hydraulic oil pressure in the oil-side diaphragm chamber 111 of the diaphragm compressor increases synchronously with the air pressure. At this time, the hydraulic oil that flows into the oil-side diaphragm chamber 111 of the diaphragm compressor through the connecting pipeline during the expansion phase will all flow into the reservoir oil chamber 209. In this way, the total flow rate that can be reduced by the diaphragm compressor in the working cycle is Δq v .

[0082] Before the diaphragm compressor is adjusted in flow rate, several liquid reservoirs 20 with different volumes can be connected in parallel. The different volumes of these liquid reservoirs 20 are designed to meet various flow rate requirements, so as to facilitate flexible adjustment. Figure 5 As shown, three liquid reservoirs 20 are connected in parallel.

[0083] like Figure 5 The embodiment of the present invention further includes a control system 30, which includes a PLC control module 301, an oil pressure sensor 302, and a flow meter 303. The flow meter 303 is connected to the exhaust pipeline of the diaphragm compressor; the oil pressure sensor 302 is connected to the oil side membrane chamber 111 of the diaphragm compressor; the PLC control module 301 is respectively connected to the oil pressure sensor 302, the flow meter 303, and the control valve signal of the liquid storage device 20.

[0084] Specifically, the control valve of the liquid storage device is controlled by the PLC control module 301. The diaphragm compressor is provided with an oil pressure sensor 302 and a flow meter 303. The signals of the flow meter 303 and the oil pressure sensor 302 are transmitted to the PLC control module 301. The PLC control module 301 receives the signals of the oil pressure sensor 302 and the flow meter 303, and analyzes the oil overflow pressure and the oil pressure at the end of suction through data processing. The PLC control module 301 selects to open the switches of several parallel liquid storage devices according to the target flow rate.

[0085] The flow rate regulation method of the diaphragm compressor of the present invention is further described below through specific embodiments.

[0086] See also Figures 2 to 5 A diaphragm compressor flow control method is applied to a diaphragm compressor, wherein the diaphragm compressor comprises a diaphragm head structure 10, wherein the diaphragm head structure 10 has an oil side diaphragm cavity 111; the structure of the diaphragm head structure 10 is as follows Figure 1 The diaphragm compressor flow regulation method includes the following steps:

[0087] Step 1, connecting the oil-side membrane cavity 111 to the plurality of reservoir oil cavities 209 through pipelines; each reservoir 20 has a reservoir oil cavity 209, and the outlet of each reservoir oil cavity 209 is provided with a control valve.

[0088] In the embodiment of the present invention, the number of the liquid reservoir 20 is at least one, and the specific number of the liquid reservoir 20 can be selected according to actual needs. When the number of the liquid reservoirs 20 is ≥ 2, multiple liquid reservoirs 20 are connected in parallel. In the embodiment of the present invention, before the diaphragm compressor adjusts the flow rate, a plurality of liquid reservoirs 20 with different volumes can be connected in parallel. The different volume designs of these liquid reservoirs 20 are intended to meet various flow rate adjustment requirements. The structure of the liquid reservoir 20 is as follows: Figure 2 shown.

[0089] Step 2, obtain the volume of hydraulic oil in each reservoir oil chamber 209 entering the oil side membrane chamber 111 and the volume of hydraulic oil expansion in the oil side membrane chamber 111 when the diaphragm compressor ends suction, so as to calculate the adjustable flow rate of each reservoir 20 in the working cycle of the diaphragm compressor.

[0090] The embodiment of the present invention can calculate the adjustable flow rates of the liquid reservoirs 20 of different capacities in sequence according to the method of step 2. The calculation formula of the adjustable flow rate of each liquid reservoir 20 in the working cycle of the diaphragm compressor is as follows:

[0091] Δq v =(Δv oil +Δv oil-e ) T λ p λv-e n;

[0092] Wherein, Δq v represents the adjustable flow rate of a liquid reservoir in the working cycle of the diaphragm compressor; Δv oil represents the volume of hydraulic oil entering the oil-side membrane cavity from the oil cavity of a liquid reservoir at the end of the suction of the diaphragm compressor; Δv oil-e represents the volume of expansion of the hydraulic oil in the oil-side membrane cavity at the end of the suction of the diaphragm compressor; λ T represents the temperature coefficient caused by the intake heating of the diaphragm compressor; λ p is the pressure coefficient caused by the resistance loss of the diaphragm compressor; λ v-e is the gas expansion coefficient caused by the clearance volume of the diaphragm compressor; n represents the rotational speed of the diaphragm compressor.

[0093] Each of the said liquid reservoirs 20 is provided with a liquid reservoir gas cavity 208; The method for obtaining the volume of hydraulic oil entering the oil-side membrane cavity 111 from the oil cavity of a liquid reservoir at the end of the suction of the diaphragm compressor is as follows:

[0094] Obtain the volume of the liquid reservoir gas cavity, the oil spill pressure of the diaphragm compressor, and the oil pressure at the end of the suction of the diaphragm compressor, so as to calculate the volume of hydraulic oil entering the oil-side membrane cavity 111 from the oil cavity of a liquid reservoir at the end of the suction of the diaphragm compressor, denoted as Δv oil . Δv oil The calculation formula of is as follows:

[0095]

[0096] Wherein, Δv oil represents the volume of hydraulic oil entering the oil-side membrane cavity from the oil cavity of a liquid reservoir at the end of the suction of the diaphragm compressor; v o represents the volume of the liquid reservoir gas cavity; p 0 represents the oil spill pressure of the diaphragm compressor; p 1 represents the oil pressure at the end of the suction of the diaphragm compressor; m represents the process index.

[0097] The method for obtaining the volume of expansion of the hydraulic oil in the oil-side membrane cavity 111 at the end of the suction of the diaphragm compressor is as follows:

[0098] Obtain the oil spill pressure of the diaphragm compressor, the oil pressure at the end of the suction of the diaphragm compressor, and the total volume of all the hydraulic oil in the oil-side membrane cavity and the liquid reservoir oil cavity communicating with the oil-side membrane cavity at the end of the exhaust of the diaphragm compressor, and calculate the volume of expansion of the hydraulic oil in the oil-side membrane cavity 111 at the end of the suction of the diaphragm compressor, denoted as Δv oil-e . Δv oil-e The calculation formula of is as follows:

[0099] Wherein, Δvoil-e It indicates the volume of the hydraulic oil expanded in the oil-side diaphragm chamber when the diaphragm compressor is finished sucking air; p 0 Indicates the overflow oil pressure of the diaphragm compressor; p 1 Indicates the oil pressure at the end of the diaphragm compressor suction; β indicates the bulk elastic modulus of the hydraulic oil; v oil-tdc It indicates the total volume of all hydraulic oil in the oil-side diaphragm chamber and the reservoir oil chamber connected to the oil-side diaphragm chamber when the diaphragm compressor is exhausted.

[0100] Step 3, obtaining the required control flow of the diaphragm compressor.

[0101] The embodiment of the present invention calculates the required control flow of the diaphragm compressor according to the target flow of the diaphragm compressor and the actual flow of the diaphragm compressor. Specifically, the required control flow of the diaphragm compressor is calculated by using the difference between the target flow of the diaphragm compressor and the actual flow of the diaphragm compressor. The actual flow of the diaphragm compressor is obtained by reading the flow meter 303 connected to the exhaust pipe of the diaphragm compressor.

[0102] Step 4, compare the required control flow of the diaphragm compressor with the control flow available for each liquid reservoir 20 in the working cycle of the diaphragm compressor, and open the control valve of the liquid reservoir 20 that matches the required control flow of the diaphragm compressor.

[0103] Step 5, after executing step 4 and the diaphragm compressor is adjusted to work stably, the actual flow of the diaphragm compressor is obtained; when the actual flow of the diaphragm compressor meets the following conditions, the adjustment program is terminated:

[0104] (1-λ)q g ≤q≤(1+λ)q g ; where λ is the control margin factor, q g is the target flow rate of the diaphragm compressor, and q is the actual flow rate of the compressor.

[0105] Step 6, after executing step 4, the diaphragm compressor is adjusted to work stably, the actual flow of the diaphragm compressor is obtained; when the actual flow of the diaphragm compressor does not satisfy (1-λ)q g ≤q≤(1+λ)q g If the condition is met, the following steps are performed:

[0106] When q<(1-λ)q g When the flow rate of the diaphragm compressor is less than 100%, the control valve of the liquid storage device 20 that matches the required control flow rate of the diaphragm compressor is closed, and the control valve of the liquid storage device 20 that is close to the required control flow rate of the diaphragm compressor is opened; step 5 is executed until the actual flow rate of the diaphragm compressor satisfies (1-λ)q g ≤q≤(1+λ)q g After the condition is met, the adjustment procedure is terminated.

[0107] Step 7, when q>(1+λ)q g , execute steps 3 to 5 until the actual flow rate of the diaphragm compressor satisfies (1-λ)q g ≤q≤(1+λ)q g After the condition is met, the adjustment procedure is terminated.

[0108] In the embodiment of the present invention, the liquid reservoirs 20 of different capacities are sorted according to the size of the adjustable flow rate, and the liquid reservoir 20 that is close to the required adjustable flow rate of the diaphragm compressor is the next liquid reservoir 20 in this sorting.

[0109] In summary, the embodiment of the present invention realizes stepless regulation of the flow rate of the diaphragm compressor by increasing the number of liquid storage devices with different volumes in parallel, and the energy loss is small during the flow regulation, and will not affect the stability of the system or have a negative impact on the life of the compressor. It has a simple structure, convenient installation and low cost, and can demonstrate good performance and high operability during the flow regulation process.

[0110] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A diaphragm compressor flow regulation method, applied to a diaphragm compressor, wherein the diaphragm compressor comprises a diaphragm head structure, wherein the diaphragm head structure has an oil-side diaphragm cavity; characterized in that: The following steps are involved: The oil-side membrane cavity is connected to a plurality of liquid reservoirs through pipelines; each of the liquid reservoirs has a liquid reservoir oil cavity, and the outlet of each liquid reservoir oil cavity is provided with a control valve; The volume of hydraulic oil in each reservoir oil chamber entering the oil side diaphragm chamber and the volume of hydraulic oil expansion in the oil side diaphragm chamber are obtained at the end of suction of the diaphragm compressor, so as to calculate the adjustable flow rate of each reservoir in the working cycle of the diaphragm compressor; Obtain the required regulated flow of the diaphragm compressor; Compare the required control flow of the diaphragm compressor with the available control flow of each liquid reservoir in the working cycle of the diaphragm compressor, and open the control valve of the liquid reservoir matching the required control flow of the diaphragm compressor; After the diaphragm compressor is adjusted to work stably, obtain the actual flow rate of the diaphragm compressor; The regulation process is terminated when the actual flow of the diaphragm compressor meets the following conditions: (1-λ)q g ≤q≤(1+λ)q g ; where λ is the regulation margin factor, q g is the target flow rate of the diaphragm compressor, and q is the actual flow rate of the diaphragm compressor.

2. The diaphragm compressor flow rate regulation method according to claim 1, characterized in that: 0.1<λ<0.

15.

3. The diaphragm compressor flow rate regulation method according to claim 1, characterized in that: When the actual flow rate of the diaphragm compressor does not satisfy (1-λ)q g ≤q≤(1+λ)q g If the condition is met, the following steps are performed: When q<(1-λ)q g When the flow rate of the diaphragm compressor is regulated, the control valve of the liquid storage device that matches the required regulated flow rate of the diaphragm compressor is closed, and the control valve of the liquid storage device that is close to the required regulated flow rate of the diaphragm compressor is opened; Return to the step of obtaining the actual flow rate of the diaphragm compressor after the diaphragm compressor is adjusted to work stably, until the actual flow rate of the diaphragm compressor satisfies (1-λ)q g ≤q≤(1+λ)q g After the condition is met, the adjustment procedure is terminated.

4. The diaphragm compressor flow rate regulation method according to claim 1, characterized in that: When the actual flow rate of the diaphragm compressor does not satisfy (1-λ)q g ≤q≤(1+λ)q g If the condition is met, the following steps are performed: When q>(1+λ)q g , return to the step of calculating the required control flow of the diaphragm compressor, and at the same time, compare the calculated required control flow of the diaphragm compressor with the available control flow of each liquid reservoir in the working cycle of the diaphragm compressor until the actual flow of the diaphragm compressor satisfies (1-λ)q g ≤q≤(1+λ)q g After the conditions are met, the control valve of the liquid reservoir matching the required regulating flow of the diaphragm compressor is opened and the regulating procedure is terminated.

5. The diaphragm compressor flow rate regulation method according to claim 1, characterized in that: The calculation formula for the adjustable flow rate of each liquid reservoir in the working cycle of the diaphragm compressor is as follows: Δq v =(Δv oil +Δv oil-e )l T l p l v-e n; Among them, Δq v Indicates the adjustable flow rate of a liquid reservoir in the working cycle of the diaphragm compressor; Δv oil Indicates the volume of hydraulic oil in a reservoir oil chamber entering the oil side diaphragm chamber when the diaphragm compressor ends suction; Δv oil-e Indicates the volume of the hydraulic oil expanded in the oil-side diaphragm chamber when the diaphragm compressor is finished sucking air; T Indicates the temperature coefficient caused by the intake air heating of the diaphragm compressor; λ p is the pressure coefficient caused by the resistance loss of the diaphragm compressor; v-e is the gas expansion coefficient caused by the clearance volume of the diaphragm compressor; n is the rotation speed of the diaphragm compressor.

6. The diaphragm compressor flow rate regulation method according to claim 5, characterized in that: Each of the liquid reservoirs has a liquid reservoir air cavity; the method for obtaining the volume of hydraulic oil in a liquid reservoir oil cavity entering the oil side diaphragm cavity when the diaphragm compressor ends suction is as follows: Obtain the volume of the reservoir cavity, the overflow oil pressure of the diaphragm compressor, and the oil pressure at the end of the diaphragm compressor suction to calculate the volume of the hydraulic oil in a reservoir oil cavity entering the oil side diaphragm cavity at the end of the diaphragm compressor suction, recorded as Δv oil ; Δv oil The calculation formula is as follows: Among them, v o It represents the volume of the air cavity of the liquid storage device; p0 represents the oil overflow pressure of the diaphragm compressor; p1 represents the oil pressure at the end of the diaphragm compressor suction; m represents the process index.

7. The diaphragm compressor flow rate regulation method according to claim 5, characterized in that: The method for obtaining the volume of the hydraulic oil expansion in the oil-side diaphragm chamber at the end of the diaphragm compressor suction is as follows: Obtain the overflow oil pressure of the diaphragm compressor, the oil pressure at the end of the diaphragm compressor suction, and the total volume of all hydraulic oil in the oil-side diaphragm chamber and the reservoir oil chamber connected to the oil-side diaphragm chamber at the end of the diaphragm compressor exhaust. Calculate the volume of the hydraulic oil expansion in the oil-side diaphragm chamber at the end of the diaphragm compressor suction, recorded as Δv oil-e ; Δv oil-e The calculation formula is as follows: Among them, p0 represents the overflow oil pressure of the diaphragm compressor; p1 represents the oil pressure at the end of the diaphragm compressor suction; β represents the bulk elastic modulus of the hydraulic oil; v oil-tdc It indicates the total volume of all hydraulic oil in the oil-side diaphragm chamber and the reservoir oil chamber connected to the oil-side diaphragm chamber when the diaphragm compressor is exhausted.

8. The diaphragm compressor flow rate regulation method according to claim 1, characterized in that: The liquid reservoir includes a liquid reservoir shell, a floating piston and a liquid reservoir end cover; the liquid reservoir end cover is fixedly connected to the liquid reservoir shell and is used to seal the liquid reservoir shell; the floating piston is slidably configured in the liquid reservoir shell so that the internal spaces of the liquid reservoir shell and the liquid reservoir end cover are separated to form a liquid reservoir oil chamber and a liquid reservoir air chamber.

9. The diaphragm compressor flow rate regulation method according to claim 8, characterized in that: The oil cavity of the liquid reservoir has an oil circuit, and the control valve of the liquid reservoir is arranged on the corresponding oil circuit; the air cavity of the liquid reservoir is arranged with an end cover air suction pipeline, and the end cover air suction pipeline is arranged with an end cover air suction valve.

10. The diaphragm compressor flow rate regulation method according to claim 1, characterized in that: The diaphragm compressor also includes a control system, which includes a PLC control module, an oil pressure sensor and a flow meter; the flow meter is connected to the exhaust pipeline of the diaphragm compressor; the oil pressure sensor is connected to the oil side diaphragm cavity of the diaphragm compressor; the PLC control module is respectively connected to the oil pressure sensor and the flow meter as well as the control valve signal of the liquid storage device.

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