Hydraulic gas compressor

Abstract

A hydraulic compressor equipped with a liquid pump that moves an incompressible liquid in and out of a compression chamber, thereby pushing the gas and transferring it to a gas storage tank by mass transfer. The gas is compressed to a desired pressure in the gas storage tank. The system comprises multiple compression tanks, each containing interdependent volumes of liquid and gas. One or more pumps move the liquid to a first compression tank, thereby discharging the gas from the first compression tank, which is then guided to a gas storage tank where it is compressed. In each of these compression tanks, the liquid is held within an expandable bladder.

Description

Technical Field

[0001] The present invention relates to the field of gas compression using a liquid pump and a plurality of compression tanks.

Background Art

[0002] Gas compressors are used in a wide range of fields such as industry, medicine, and housing. Most gas compressors are air compressors, but there are also many other applications where gas compression is required, such as refrigerant compressors, natural gas compressors, oxygen compressors, and compressors for highly reactive gases. According to some studies, it has been revealed that the energy consumption due to the use of air compressors accounts for about 10% of the total global energy consumption. Therefore, energy savings in the compression of air and gas can potentially bring very large economic benefits. The most common types of positive displacement compressors include reciprocating (piston or diaphragm type) and rotary (screw, vane type) compressors, and the choice of which type of compressor to use depends on the nature of the fluid to be compressed and the required pressure and volume. All positive displacement compressors use solid elements to compress the fluid, and most of the energy consumed is converted into heat. Conventional air compression systems are inherently inefficient, remaining at about 5 - 15%, which means a large waste of energy. Certainly, improving the energy efficiency of air compression systems reduces the energy consumption for air compression in the industrial field and greatly contributes to global sustainable growth. Furthermore, conventional positive displacement compressors often use oil lubrication, and an expensive filtration device is required to prevent oil mist and hydrocarbon gas from mixing into the storage tank of the compressed gas.

[0003] Hydropneumatic gas compression, which uses a liquid piston and pump to compress gas, is a new concept developed by the inventors and offers many advantages over conventional compressors that use solid elements to compress fluids. Hydropneumatic gas compression allows for isothermal cycles during compression, resulting in higher energy efficiency compared to adiabatic cycles. However, the concept of hydropneumatic gas compression itself (compressing air using a liquid) is not new. In fact, the technique was first described in 1879 (Mekarski, Louis, 'Improvement in devices for using compressed air for motive power', 8683, April 22, 1879). Although they have received relatively little attention until now, the pursuit of energy efficiency has led to renewed interest in hydropneumatic air systems for energy storage (European Patent Publication No. 3789609, US Patent Publication No. 2021 / 0075296, International Publication No. 2021 / 250666, Chinese Patent No. 110985356) and general gas compression (US Patent No. 5073090, German Patent Publication No. 4430716, Chinese Patent No. 102840183). However, known prior art does not fully utilize the energy efficiency improvement potential of the principle of hydropneumatic gas compression, nor does it possess the robustness necessary to enable efficient and reliable commercial operation.

[0004] For example, U.S. Patent No. 5073090 teaches a system in which a compressor has two hollow chambers, which are interconnected by a piping system equipped with pumps. The compressor contains a sufficient amount of incompressible transfer fluid, which completely fills one of the cylinders and the piping system. A switching system pumps the transfer fluid into the first chamber and then transfers the transfer fluid from the first chamber to the second chamber. In such a system, the liquid is in direct contact with the gas, and there is a risk that the liquid may accidentally enter the storage tank when the cylinder is filled with liquid. Therefore, in practice, such a system must operate in a range considerably lower than the maximum compression ratio.

[0005] Similarly, Chinese Patent No. 102840183 discloses a system in which a liquid is in open contact with a gas, and a liquid level sensor is used to detect the maximum filling level of the compression tank. Therefore, there is a need for an energy-efficient system that enables operation close to the theoretical maximum efficiency, is robust enough to avoid the risk of liquid moving into the storage tank, and is simple and reliable to operate. The present invention aims to address many of these problems in the prior art. [Overview of the Initiative]

[0006] <Effects of the invention> Some of the advantages of this disclosure that at least one embodiment satisfies are as follows:

[0007] The first advantage of the present invention is that it improves efficiency and reliability by providing a method and system for compressing gas using the movement of a liquid.

[0008] Another advantage of the present invention is that it provides a method and system for enabling maintenance without loss of production time by compressing a gas using the movement of a liquid.

[0009] This invention utilizes a liquid pump to move an incompressible liquid in and out of a compression chamber, thereby pushing out the gas and transferring it to a gas storage tank by mass transfer. The gas is then compressed to a desired pressure within the gas storage tank. The system comprises multiple compression tanks, each containing interdependent volumes of liquid and gas. One or more pumps move the liquid through a first compression tank, thereby discharging the gas from the first compression tank, which is then guided to a gas storage tank where it is compressed. In each of these compression tanks, the liquid is held within an inflatable bladder (a bag-like container). Liquid can be supplied to the inflatable bladder in the compression tank through a dedicated passage, causing the bladder to expand volumetrically, which in turn discharges the gas from each compression tank and guides it to a gas storage tank connected to the compression tanks. The liquid circulates within a sealed system, with the first half of the cycle involving liquid moving from an inflatable bladder in one compression tank to an inflatable bladder in another compression tank. Then, when the bladder of the first compression tank reaches the end of its forward stroke, the operation is reversed. Gas is supplied to the compression tank via a low-pressure gas source. If the gas is atmospheric air, the low-pressure gas source is usually the atmosphere.

[0010] In a first aspect of the present invention, a hydraulic compressor system for compressing a gas comprises at least one pump, a gas storage tank, a first compression tank, and a second compression tank. Each compression tank is An inflatable bladder, The bladder space formed inside it, Located outside the inflatable bladder, it contains a tank space with compressible gas, A liquid line configured to fluidly connect at least one of the one or more pumps to an inflatable bladder space, through which a liquid is pumped into or out of the inflatable bladder; A gas line configured to fluidly connect a tank space and a gas storage tank, wherein gas enters and leaves the tank space through the gas line, Includes. An expandable bladder holds liquid within its expandable bladder space, and is configured to expand when liquid is supplied to the expandable bladder space. The expansion of the expandable bladder pressurizes the gas, achieving mass transfer from the compression tank to the gas storage tank. As the mass transfer of gas (m) occurs in the gas storage tank, the pressure in the gas storage tank increases according to the ideal gas law PV=mRT, where P is the pressure, V is the volume of the gas storage tank, m is the mass of gas in the storage tank, T is the absolute temperature, and R is a constant. During system operation, one or more pumps pump liquid into the expandable bladder in the first compression tank, and gas is discharged from the tank space of the first compression tank and guided to the gas storage tank, where it is compressed.

[0011] Because the liquid flows into the internal space of the expandable bladder, there is no direct contact between the gas and liquid. Even at the end of the compression stroke, there is no risk of liquid moving into the transfer line connecting the compression tank and the gas storage tank. The expandable bladder expands to its maximum extent, allowing it to transfer almost all of the gas (mass) in the compression tank to the gas storage tank, resulting in high efficiency.

[0012] The first compression tank is configured to operate in a compression stroke and a return stroke. During the compression stroke, liquid is pumped through the liquid line into an inflatable bladder, which is configured to expand into the tank space to compress the gas. During the return stroke, liquid flows out of the inflatable bladder through the liquid line, which is configured to contract and expand the tank space.

[0013] The liquid line of the first compression tank is fluidly connected to the liquid line of the second compression tank, When the first compression tank is configured to operate in the return stroke and the second compression tank is configured to operate in the compression stroke, the liquid is configured to flow out of the inflatable bladder of the first compression tank and be supplied by the pump to the inflatable bladder of the second compression tank. When the second compression tank is configured to operate in the return stroke and the first compression tank is configured to operate in the compression stroke, the liquid is configured to flow out of the inflatable bladder of the second compression tank and be supplied by the pump to the inflatable bladder of the first compression tank.

[0014] In some embodiments, An inflow line extending between the low-pressure gas source and the tank space, A check valve that controls the gas flow between the tank space and the low-pressure gas source, In the aforementioned gas line, a check valve controls the flow of gas between the tank space and the gas storage tank, It is further equipped with [this feature].

[0015] In a preferred embodiment, during the operation of the system, the volume ratio (Vc / Vo) of the volume of the tank space at the end of the compression stroke to the volume of the tank space at the beginning of the compression stroke is 0.1 or less.

[0016] Each compression tank is equipped with a pressure sensor, which is positioned to measure the pressure of the liquid in the inflatable bladder.

[0017] The aforementioned pump is characterized by the pump stall pressure, The maximum pressure of the liquid in the expandable bladder is set to less than 10% of the pump stall pressure. The minimum pressure of the liquid in the expandable bladder is less than 5% of the pump stall pressure.

[0018] In one embodiment, The pump includes a variable speed pump, and the pump speed is adjusted to be decelerated toward the end of the compression stroke, whereby the liquid flow rate decreases, and smooth switching from one compression tank to another compression tank is possible when the automatically controlled shut-off valve is opened and closed.

[0019] In another embodiment, the system includes a pair of pumps consisting of two pumps, the two pumps are connected in parallel and are configured to operate as one unit, of the pair of pumps, the first pump has a high flow capacity but a low pressure upper limit, the second pump has a low flow capacity but a high pressure upper limit.

[0020] The system further includes a plurality of liquid lines, each liquid line is configured to connect a hydraulic compression tank to one or more of the one or more pumps, each liquid line includes at least two shut-off valves, each liquid line is configured to connect each compression tank to one or more of the one or more pumps within a closed circuit, each liquid line includes a forward shut-off valve and a return shut-off valve, when the hydraulic compression tank is configured to operate in the compression stroke, the forward shut-off valve is open and the return shut-off valve is closed, when the hydraulic compression tank is configured to operate in the return stroke, the forward shut-off valve is closed and the return shut-off valve is open.

[0021] The shut-off valve is controlled by a control system, and the control system is configured to open and close the shut-off valve based on data received from a sensor system. In a preferred embodiment, the sensor system A pressure sensor is positioned to measure the pressure of the liquid in the inflatable bladder within each hydraulic compression chamber, A pressure sensor is positioned to measure the pressure inside the gas storage tank, Includes.

[0022] In another embodiment, The aforementioned sensor system, A flow meter fluidly connected to the expandable bladder in each hydraulic compression chamber, A pressure sensor is positioned to measure the pressure inside the gas storage tank, Includes.

[0023] In yet another embodiment, The aforementioned sensor system, A flow meter fluidically connected to the pump discharge side, A pressure sensor is fluidly connected to the storage tank, Composed of, If the gas intake pressure is constant, no other sensors are needed.

[0024] In one embodiment, The control system is Before the compression stroke is initiated, data corresponding to the pressure of the liquid in the expandable bladder is received. After the compression stroke is initiated, data corresponding to the pressure of the liquid in the expandable bladder is received. Calculate the compression ratio (Vc / Vo). Determine whether the compression ratio has reached its maximum value. When the compression ratio reaches its maximum value, the shut-off valve is switched from open to closed or from closed to open. It is configured in this way.

[0025] In another embodiment, the control system is configured to switch the shut-off valve from open to closed or from closed to open when the pump reaches a stall condition defined by the pump current.

[0026] In yet another embodiment, The automatic switching of the system from the forward compression cycle of the first compression tank to the forward compression cycle of the second compression tank and the return stroke of the first compression tank occurs with a time difference between the opening operation of the second forward valve and the first reverse valve and the closing operation of the first forward valve and the second reverse valve. The aforementioned time difference is in the range of 1 / 10 to 1 / 2 of the time required for the shut-off valve to fully open.

[0027] Another aspect of the system concerns the number of compression tanks. In one embodiment, there are two compression tanks. In another embodiment, the plurality of compression tanks include three or more tanks, Each tank is connected to a dedicated passage through which liquid is supplied and gas is forced out. The aforementioned dedicated passageway is A pressure sensor for measuring liquid pressure or a flow meter for measuring liquid flow rate, A pair of shut-off valves that control the flow of liquid from the pump to the compression tank during the compression stroke and control the flow of liquid from the compression tank to the pump during the return stroke, Equipped with, The operating timing of the shut-off valves corresponding to each of the multiple tanks is adjusted so that one or more of the pumps do not reach a stall condition.

[0028] An expandable bladder within a compression tank is elastic and characterized by a spring constant that defines its resistance to expansion.

[0029] The inflatable bladder can be any size depending on the overall system capacity. The volume of the compression tank and the inflatable bladder contained within it is a function of the volume of the gas storage tank and the target pressure in that gas storage tank divided by the number of switch overcycles. Here, the number of switch overcycles refers to the number of cycles in which the liquid moves from one bladder to the other.

[0030] The system is operated to maximize energy efficiency for compressing the gas.

[0031] According to a preferred embodiment, the method for compressing a gas according to the present invention is: a. Step of providing a first compression tank. The first compression tank includes, i. An inflatable bladder defining a bladder space, wherein the inflatable bladder stores a liquid within the inflatable bladder space, ii. A tank space containing compressible gas, located outside the inflatable bladder, iii. Liquid input section and, iv. Gas port and, Equipped with, The aforementioned method further, v. The step of connecting the gas port of the first compression tank to a gas storage tank via a gas line, vi. The step of connecting the liquid input section of the first compression tank to the first liquid line, b. The step of operating the first compression tank in either a compression stroke or a return stroke, Includes, The step of operating the first compression tank with the compression stroke is: i. The step of pumping the liquid through the first liquid line into the expandable bladder space in the first compression tank to compress the gas in the tank space of the first compression tank, thereby causing the expandable bladder of the first compression tank to expand into the tank space, ii. The steps of discharging the gas from the tank space of the first compression tank through the gas port and recovering the gas in the gas storage tank, iii. The step of further compressing the gas in the gas storage tank, Includes, The step of operating the first compression tank in the return stroke is: i. The step of pumping the liquid out of the expandable bladder space in the first compression tank via the first liquid line so that the expandable bladder of the first compression tank contracts, thereby increasing the volume of the tank space in the first compression tank, ii. A step of filling the tank space of the first compression tank with gas from a low-pressure gas source via the gas port, Includes.

[0032] According to one embodiment, The aforementioned method further, a. Step of providing a second compression tank. The second compression tank includes, i. An inflatable bladder defining a bladder space, wherein the inflatable bladder stores a liquid within the inflatable bladder space, ii. A tank space containing compressible gas, located outside the inflatable bladder, iii. Liquid input section and, iv. Gas port and, Equipped with, The aforementioned method further, b. A step of connecting the gas port of the second compression tank to a gas storage tank via a gas line, wherein the first and second compression tanks may be connected to the same gas storage tank or to different gas storage tanks. c. A step of connecting the liquid input section of the second compression tank to a second liquid line, wherein the first liquid line and the second liquid line are in fluidic communication. d. The steps of operating the first compression tank in a compression stroke and the second compression tank in a return stroke, Includes, The aforementioned step is, e. Pumping liquid from the expandable bladder space of the second compression tank to the expandable bladder space of the first compression tank compresses the gas in the tank space of the first compression tank, thereby causing the expandable bladder of the second compression tank to contract and the expandable bladder of the first compression tank to expand; f. The steps of discharging the gas from the tank space of the first compression tank through the gas port of the first hydraulic chamber and recovering the gas in the gas storage tank, g. A step of filling the tank space of the second compression tank with gas from a low-pressure gas source through the gas port of the second hydraulic chamber, h. The step of further compressing the gas in the gas storage tank, Includes.

[0033] In another embodiment, The aforementioned method further, a. A step of determining that the compression stroke of the first compression tank has been completed and / or that the return stroke of the second compression tank has been completed, b. The steps of switching the operation of the first and second compression tanks, operating the second compression tank in a compression stroke, operating the first compression tank in a return stroke, and pumping liquid from the expandable bladder space of the first compression tank to the expandable bladder space of the second compression tank, thereby compressing the gas in the tank space of the second compression tank, thereby causing the expandable bladder of the first compression tank to contract and the expandable bladder of the second compression tank to expand, c. Discharging the gas from the tank space of the second compression tank through the gas port of the second hydraulic chamber and recovering the gas in the gas storage tank, d. A step of filling the tank space of the first compression tank with gas from a low-pressure gas source through the gas port of the second hydraulic chamber, e. The step of further compressing the gas in the gas storage tank, Includes.

[0034] Hereinafter, examples of preferred embodiments of the present invention will be described with reference to the attached drawings. [Brief explanation of the drawing]

[0035] [Figure 1] Figure 1 is a schematic diagram showing the basic configuration of a hydraulic gas compression system equipped with two compression tanks according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing the typical gas volume in a compression tank at the start and end of the compression stroke. [Figure 3] Figure 3 is a schematic diagram of the system showing the operation of the compression stroke in the first tank and the corresponding liquid flow. [Figure 4] Figure 4 is a schematic diagram of a system that demonstrates the use of a three-way valve. [Figure 5a] Figure 5a is a schematic diagram of a system showing alternative means for measuring pressure and flow rate. [Figure 5b] Figure 5b is a schematic diagram of a system showing alternative means for measuring pressure and flow rate. [Figure 5c] Figure 5c is a schematic diagram of a system showing alternative means for measuring pressure and flow rate. [Figure 6] Figure 6 is a schematic diagram of the system showing the configuration of the control system. [Figure 7] Figure 7 is an example of a flowchart illustrating a control operation. [Figure 8] Figure 8 shows an example of a typical curve of pressure over time. [Figure 9] Figure 9 is a schematic diagram of a system showing an embodiment in which multiple pumps are used in parallel. [Figure 10]Figure 10 is a schematic diagram showing the use of more than two compression tanks. [Figure 11] Figure 11 is a schematic diagram illustrating the use of more than two pumps and more than two compression tanks. [Figure 12] Figure 12 is a schematic diagram showing the use of valves at the pump's inlet and outlet. [Modes for carrying out the invention]

[0036] List of reference numbers in the drawing The following is a list of reference numbers used in the drawings. 1a: First gas line from the first low-pressure gas source to the first compression tank 1b: First gas line from the second low-pressure gas source to the second compression tank 10: Liquid pump 10a: Additional pump 10n: nth additional pump 11: Low-pressure side inlet of the pump 12: High-pressure discharge port of the pump 2: Hydraulic Compression Tank 21: First Hydraulic Compression Tank 210: Tank space of the first hydraulic compression tank 22: Second Hydraulic Compression Tank 22n: nth additional hydraulic compression tank 220: Tank space of the second hydraulic compression tank 3: Inflatable bladder inside a hydraulic compression tank 30: Bladder Space 31: Inflatable bladder in the first hydraulic compression tank 310: Liquid in the first bladder 32: Inflatable bladder in the second hydraulic compression tank 320: Liquid in the second bladder 4: Gas storage tank 51: First shut-off valve of the first hydraulic compression tank 52: First shut-off valve of the second hydraulic compression tank 53: Second shut-off valve of the first hydraulic compression tank 54: Second shut-off valve of the second hydraulic compression tank 55: Three-way valve for the first hydraulic compression tank 56: Three-way valve for the second hydraulic compression tank 57: Shut-off valve for the pump intake 61: First check valve of the first compression tank 62: Second check valve of the first compression tank 63: First check valve of the second compression tank 63n: First check valve of the nth additional compression tank 64: Second check valve of the second compression tank 64n: Second check valve of the nth additional compression tank 65: Check valve used at the pump outlet when using multiple pumps 66: Check valve at the pump's outlet 70: Pressure sensor for gas storage tanks 700: Measurement of gas storage tanks 71: Pressure sensor for the bladder of the first compression tank 710: Measuring pressure of the bladder corresponding to the compression stroke of the first compression tank. 72: Pressure sensor for the bladder of the second compression tank 72n: Pressure sensor for the bladder of the nth additional compression tank 720: Measurement pressure corresponding to the bladder of the second compression tank during the compression stroke of the first compression tank and the return stroke of the second compression tank. 73: Pressure sensor at the pump outlet 73a: Pressure sensor at the pump outlet of the additional pump 73n: Pressure sensor at the pump outlet of the nth additional pump 730: Pump pressure measured at the pump outlet 731: Maximum liquid pressure at the pump outlet 732: Slope of the tank pressure curve 733: Near-zero pressure in the second compression tank 740: Pressure of the liquid at the pump outlet 74: Flow meter associated with the first compression tank 75: Flow meter associated with the second compression tank 76: Flow meter associated with the outlet of a liquid pump 80: Controller 81: Wireless Communication 82: Computing Devices 91: Liquid piping with low-pressure liquid 92: Liquid piping with high-pressure liquid 93a: Second gas line from the first hydraulic compression chamber to the gas storage tank 93b: Second gas line from the second hydraulic compression chamber to the gas storage tank

[0037] Detailed explanation This invention relates to a hydraulic gas compression system.

[0038] This system includes the following main components: one or more liquid pumps, two or more compression tanks with expandable bladders inside, one or more pressurized gas storage tanks, multiple shut-off valves, each corresponding to a compression tank, multiple check valves, each corresponding to a compression tank, dedicated flow paths, measuring instruments, and a control system.

[0039] The principles and structural details of the present invention will be described with reference to the following examples of alternative embodiments. These embodiments illustrate the principles of the present invention and do not impose any limitations on their structural arrangement.

[0040] Figure 1 is a schematic diagram showing the basic configuration of a hydraulic gas compression system comprising two compression tanks according to one embodiment of the present invention. The system includes a liquid pump 10, a first compression tank 21, a second compression tank 22, and a gas storage tank 4. Inside each compression tank are inflatable bladders 31 and 32, respectively. When the pump 10 pumps liquid into the first hydraulic compression tank 31, the liquid is supplied to the inflatable bladders within the first hydraulic compression tank 31, and the liquid in the first bladders 310 inflates the inflatable bladders, thereby pushing out the gas in the gas space of the first compression tank 210. The gas flows into the gas storage tank 4 through dedicated gas lines 93a and 93b, where it is compressed. Each hydraulic compression tank 21 and 22 is associated with a set of shut-off valves 51, 52, 53, and 54 and a set of check valves 61, 62, 63, and 64. Various measuring instruments are used to measure pressure and flow rate. Figure 1 shows a sensing arrangement of a preferred embodiment, comprising a pressure sensor 70 for the gas storage tank 4 and pressure sensors 71, 72 for measuring the pressure in the inflatable bladders of the first and second compression tanks 21 and 22, respectively. The gas storage tank 4 may include a bank of several individual tanks. The hydraulic compression tanks 21 and 22 have interdependent volumes, and the total volume of the tanks is equal to the sum of the gas volume 210 and the volume of the liquid-filled inflatable bladder 310. Using an inflatable bladder allows for effective use of compression over the entire stroke while avoiding the risk of liquid being carried into the gas storage tank. In contrast, without a bladder, the liquid and gas would be in direct contact within the hydraulic compression tank. Therefore, as the residual gas volume in the compression tank 210 decreases and approaches zero, the risk of liquid being carried over into the gas storage tank 4 increases.

[0041] The gas can include, but is not limited to, any gas such as air, nitrogen, hydrogen, oxygen, and even refrigerant gases. Using a bladder allows for the efficient compression of gases that readily dissolve in liquids, eliminating concerns about tiny bubbles in the liquid. Bladder use is also important when compressing highly reactive or corrosive gases such as oxygen.

[0042] Figure 2 is a schematic diagram showing the typical gas volume in a compression tank at the start and end of a compression stroke. The total volume of the compression tank 2 is represented by V, which includes (e.g., consists of) the volume of gas and the volume occupied by the expandable bladder 3 filled with liquid 30. The volume of gas in the initial state, when the expandable bladder is not substantially filled with liquid, is represented by Vo. The volume of gas in the terminal state, when the expandable bladder is expanded to its maximum capacity (e.g., filled with liquid to its maximum capacity), is represented by Vc. To maximize the efficiency of the system, it is desirable that Vc be as small as possible. According to the present invention, the Vc / Vo ratio is 0.1 or less, meaning that the expandable bladder can expand to approximately 9 times its empty state.

[0043] Figure 3 is a schematic diagram of the system showing the operation of the compression stroke in the first tank and the corresponding liquid flow. The thick lines show the liquid flow during the compression stroke of the first compression tank and the accompanying return stroke of the second compression tank. The liquid circulates within a closed circuit. During the cycle, while the first compression tank 21 is in the compression stroke phase, the pump 10 pumps liquid from the pump outlet port 12 through the high-pressure liquid piping 92 to the inflatable bladder 31 of the first compression tank, inflating the inflatable bladder in addition to the liquid in the first bladder 310. The gas in the first compression tank 210 is pushed out and moved to the gas storage tank 4 through a dedicated gas passage 93. In this case, the first check valve 61 is open to allow the gas to pass through, but the second check valve 62 is closed, preventing the gas from escaping. On the liquid side, the first shut-off valve 51 on the low-pressure side 91 connected to the first compression tank is closed, and the second shut-off valve 52 connected to the high-pressure side 92 is open, so the liquid is sent to the expandable bladder 31, causing it to expand. The liquid flows through the closed liquid circuit, and the liquid supplied to the inlet of the pump 11 flows from the expandable bladder 32 of the second compression tank. At this time, the liquid 320 in the expandable bladder passes through the second shut-off valve 54 of the second compression tank, which is connected to the low-pressure side 91. As the liquid flows out of the expandable bladder 32 of the second compression tank, the volume of the liquid 320 in the expandable bladder decreases, and the expandable bladder contracts. This lowers the gas pressure in the second compression tank, causing gas to flow from the low-pressure supply source 1b into the second compression chamber 22, and increasing the volume of the tank space 220. The second check valve 64 of the second compression tank opens to allow gas to pass through, while the first check valve 63 of the second compression tank remains closed. The second compression tank 22 is in the return stroke operation, and the first compression tank 21 is in the compression stroke operation.

[0044] The gas flows through hydraulic compression tanks 21 and 22 to the gas storage tank 4. This flow is realized through gas lines, each consisting of first gas lines 93a and 93b and second gas lines 1a and 1b. The first gas lines 93a and 93b connect the tank spaces 210 and 220 of the hydraulic compression tanks 21 and 22 to the gas storage tank. The second gas lines 1a and 1b connect the low-pressure gas source to the tank spaces 210 and 220 of the hydraulic compression tanks 21 and 22. These gas lines include ports for all pairs of check valves 61, 62, 63, and 64 and for the pressure sensor 70.

[0045] Figure 4 is a schematic diagram of a system that utilizes three-way valves. In this embodiment, a pair of shut-off valves 51 and 52 associated with the first compression tank and a pair of shut-off valves 53 and 54 associated with the second compression tank are replaced with a first three-way valve 55 and a second three-way valve 56, respectively.

[0046] Figures 5a-5c are schematic diagrams of a system showing alternative means for measuring pressure and flow rate. Figure 5a shows an embodiment in which pressure is measured using pressure sensors and the operation of the system is controlled. In this embodiment, four pressure sensors are used: pressure sensor 70 for measuring the pressure in the gas storage tank, pressure sensor 71 for measuring the liquid pressure in the inflatable bladder of the first compression tank, pressure sensor 72 for measuring the liquid pressure in the inflatable bladder of the second compression tank, and pressure sensor 73 for measuring the liquid pressure at the outlet of the liquid pump. Pressure sensors 71 and 72 for measuring the liquid pressure in the inflatable bladder are fluidically connected to the inflatable bladder and are positioned to measure the liquid pressure. The fluidic connection may be provided at a port of the fluid line supplying the bladder. The pressure in the inflatable bladder is equal to the liquid pressure being measured. This pressure corresponds to the pressure of the gas present in the tank spaces 210, 220 plus the spring constant due to the expansion of the bladder 31, 32 itself. The inflatable bladder is generally made of a flexible material and behaves like a spring when expanded. Therefore, the sum of the liquid pressures is equal to the gas pressure and the equivalent bladder resistance, P L =P G +P S This is expressed as follows: P is the liquid pressure, PG is the gas pressure in the tank space 210, 220, P S This is the pressure due to the spring-like behavior of the expandable bladder 31 and 32.

[0047] In the inflatable bladders 31 and 32, the maximum pressure generated by the spring effect during full stroke is less than 10% of the pump's stall pressure, and the minimum pressure generated by the spring effect at the end of the return stroke when the inflatable bladder reaches its minimum volume is less than 5%.

[0048] In another embodiment, instead of pressure sensors that measure the liquid pressure in the inflatable bladders 31, 32, flow meters are used to measure the inflow and outflow of liquid into the inflatable bladders corresponding to each compression tank. A flow meter 74 corresponding to the first compression tank is installed just before the liquid piping is connected to the first compression tank, and a flow meter 75 corresponding to the second compression tank is installed just before the liquid piping is connected to the second compression tank.

[0049] The operation of this system can also be controlled solely by measuring the gas pressure in the storage tank and the flow rate from the liquid pump. In this embodiment, one pressure sensor 70 is used to measure the gas pressure in the storage tank, and one flow meter 76 is used to measure the flow rate at the pump outlet. Since the liquid is in a sealed system, one flow meter alone is sufficient to indicate the amount of liquid that has moved to the first or second compression tank.

[0050] In any of the embodiments shown in Figures 5a to 5c, this system can be controlled using values ​​obtained from sensors. Furthermore, it is possible to use the current flowing through the liquid pump to indicate that the pump is approaching its maximum pressure and is nearing the stall condition.

[0051] Figure 6 is a schematic diagram of the system showing the microcontroller and system control. The shut-off valves 51, 52, 53, and 54 and sensors 70, 71, 72, 73, 74, 75, and 76 are all connected to the inputs and outputs of the control system 80. The control system includes a processor, memory, and an electronic controller. The electronic controller is connected to the pump and shut-off valves via control lines and controls their operation. The control system also has wireless communication capabilities, enabling communication with a remote computer. The remote computer may be a handheld device, a smartphone, or a remote server.

[0052] The logic for managing the system's operation is illustrated in the flowchart example showing the control operation in Figure 7. According to this example, the compression operation of each compression tank is performed via a loop process. First, the liquid pressure in the expandable bladder 31 of the first compression tank 21 is checked. If the pressure is below the maximum pressure threshold, the pump operates to continue supplying liquid to the expandable bladder 31 of the first compression tank 21, continuing compression until the maximum pressure is reached. Once the maximum pressure is reached, the "compress tank 1" operation ends, and the "compress tank 2" operation begins. In the "compress tank 2" operation, the control system uses pressure sensors 71 and 72 as the main control inputs. Based on the decision to perform either the "compress tank 1" or "compress tank 2" operation, the corresponding shut-off valves are opened and closed to ensure the flow of liquid to the expandable bladder 31 of the first compression tank. This liquid is supplied from the expandable bladder 32 of the second compression tank, if available. Conversely, when supplying to the second compression tank, liquid flows from the first compression tank.

[0053] In one embodiment, a decision is made to perform the operation of "compressing tank 1" or "compressing tank 2," and when switching from the compression stroke of the first tank to the compression stroke of the second tank, a time difference may be provided between the opening operation of the second forward valve and the first reverse valve and the closing operation of the first forward valve and the second reverse valve, and this time difference is within the range of 1 / 10 to 1 / 2 of the time required for the shut-off valve to fully open.

[0054] Figure 8 shows an example of a typical pressure curve over time. Four curves are shown on the same timeline. The four curves represent the pressure in the gas storage tank (700), the measured pressure corresponding to the bladder in the first compressor tank (710) during the compression stroke of the first compressor tank, the measured pressure corresponding to the bladder in the second compressor tank (720) during the compression stroke of the first compressor tank and the return stroke of the second compressor tank, and the measured liquid pressure at the pump outlet (740). The pump pressure reaches a peak (701) at the end of the compression stroke. This peak indicates the timing when the system switches from compressing the first tank to compressing the second tank. When the controller detects a rapid increase in pressure and the reaching of a preset reference maximum pressure threshold, it instructs the electronically controlled valve to switch operation from "compressing tank 1" to "compressing tank 2".

[0055] The system can determine that the maximum compression ratio Vc / Vo has been reached by calculating a combination of the rate of pressure increase in the expandable bladder and the time delay, regardless of the gas pressure 70 in the gas storage tank. This rate of pressure increase corresponds to the slope 732 of the tank pressure curve, which is shown as a specific example in Figure 8. At the end of the compression stroke, the rate of pressure increase of the liquid in the expandable bladder rises sharply, reaches its maximum value, and then falls to a value close to zero 733.

[0056] As mentioned above, the controller can use pressure measurement to terminate the "compress tank 1" operation and switch to the "compress tank 2" operation. It can also use pump current measurement to determine whether the pump has reached a stall condition. This stall condition is indicated by a sudden increase in current. A stall occurs either because the expandable bladder can no longer expand and the pressure has reached its maximum, or because the pump itself has reached its maximum hydraulic head and can no longer pump in any more liquid to expand the expandable bladder.

[0057] Figure 9 is a schematic diagram of a system showing an embodiment in which multiple pumps are used in parallel. Additional pumps 10a to 10n can be used together with corresponding pressure sensors 73a to 73n. In this configuration, a set of check valves 65 is used at the discharge port of each pump. By using multiple pumps, it is possible to improve efficiency and compression speed. For example, at low pressure, a pump with high flow capacity but a low pressure limit can be operated. Then, after a certain pressure threshold is exceeded, a second pump with a lower flow capacity but a higher pressure limit can be operated. In this way, the processing speed of the system can be improved, energy efficiency can be improved, and the durability of the pumps can be improved. In one embodiment, the multiple pumps are configured in a pair of two pumps that operate as a unit. This pair of pumps is connected in parallel and operates as a single unit. In this pair of pumps, the first pump has a high flow capacity but a low pressure limit, and the second pump has a low flow capacity but a high pressure limit.

[0058] Efficiency improvements can also be achieved by using more than two compression tanks. Figure 10 is a schematic diagram illustrating the use of more than two compression tanks. Figure 10 shows additional compression tanks 22n and corresponding shut-off valves 53n, 54n and check valves 63n, 64n, which are fluidically connected via fluid lines indicated by dotted lines. Each compression tank is configured with a shut-off valve, check valve and pressure sensor, and the overall system has a modular structure, making it easy to add more than two compression tanks and expandable after initial installation.

[0059] In some embodiments, efficiency improvements may be achieved by using a variable-speed pump 10. In this case, the pump speed is adjusted to decrease towards the end of the compression stroke, thereby reducing the liquid flow rate and enabling a smooth switch from one compression tank to another when an automatically controlled shut-off valve opens and closes. The operating timing of the shut-off valves corresponding to multiple tanks is set so that the pump 10 or the multiple pumps do not reach a stall condition.

[0060] Figure 11 is a schematic diagram showing the use of more than two pumps 10, 10a, and 10n, and more than two compression tanks 21, 22, and 22n. Depending on the system requirements, such as the pressure and the amount of compressed gas needed, the system configuration can be determined to achieve the optimal speed and energy efficiency.

[0061] To increase the system's tolerance to the time delay caused by the opening and closing of shut-off valves, valves can be provided at the fluid inlet and fluid outlet of the pump.

[0062] Figure 12 is a schematic diagram showing the use of valves at the pump's inlet and outlet. The check valve 66 is located on the high-pressure side (i.e., the pump's outlet side). The shut-off valve 57 is optionally installed on the low-pressure side (i.e., the pump's inlet side).

Claims

1. A hydraulic compressor system for compressing gas, At least one pump for pumping liquid, a. A gas storage tank for storing compressed gas, b. At least two compression tanks, Equipped with, Each of the aforementioned compression tanks is An inflatable bladder defining a bladder space, wherein the inflatable bladder is configured to store a liquid within the inflatable bladder space and to expand when the liquid flows into the inflatable bladder space, A tank space containing compressible gas is provided on the outside of the inflatable bladder, Includes, The inflatable bladder and the tank space outside the inflatable bladder form mutually dependent volumes of liquid and gas. The hydraulic compressor system further includes, c. A liquid line configured to fluidly connect at least one of the one or more pumps to the inflatable bladder space, wherein the liquid is pumped through the liquid line into or out of the inflatable bladder, d. A gas line configured to fluidly connect the tank space and the gas storage tank, wherein the gas enters and leaves the tank space through the gas line, Equipped with, A hydraulic compressor system in which, during operation of the system, the liquid is sent by one or more pumps to the expandable bladder in the first compression tank, and gas is discharged from the tank space of the first compression tank and led to the gas storage tank, where it is compressed.

2. The first compression tank is configured to operate in a compression stroke and a return stroke, During the compression stroke, the liquid is pumped through the liquid line to the expandable bladder, which is configured to expand into the tank space to compress the gas. During the return stroke, the liquid flows out of the inflatable bladder through the liquid line, causing the inflatable bladder to contract and the tank space to expand. The hydraulic compressor system according to claim 1.

3. The liquid line of the first compression tank is fluidly connected to the liquid line of the second compression tank. When the first compression tank is configured to operate in the return stroke and the second compression tank is configured to operate in the compression stroke, the liquid is configured to flow out of the inflatable bladder of the first compression tank and be supplied by the pump to the inflatable bladder of the second compression tank. When the second compression tank is configured to operate in the return stroke and the first compression tank is configured to operate in the compression stroke, the liquid is configured to flow out of the inflatable bladder of the second compression tank and be supplied by the pump to the inflatable bladder of the first compression tank. The hydraulic compressor system according to claim 1 or 2.

4. An inflow line extending between the low-pressure gas source and the tank space, A check valve that controls the gas flow between the tank space and the low-pressure gas source, In the aforementioned gas line, a check valve controls the flow of gas between the tank space and the gas storage tank, A hydraulic compressor system according to any one of claims 1 to 3, further comprising:

5. The volume ratio (Vc / Vo) of the volume of the tank space at the end of the compression stroke to the volume of the tank space at the beginning of the compression stroke is 0.1 or less. A hydraulic compressor system according to any one of claims 1 to 4.

6. Each compression tank is equipped with a pressure sensor, which is configured to measure the pressure of the liquid in the expandable bladder. A hydraulic compressor system according to any one of claims 1 to 5.

7. The inflatable bladder is characterized by a spring constant that defines the resistance to expansion. A hydraulic compressor system according to any one of claims 1 to 6.

8. The aforementioned pump is characterized by the pump stall pressure, The maximum pressure of the liquid in the expandable bladder is set to less than 10% of the pump stall pressure. The minimum pressure of the liquid in the expandable bladder is less than 5% of the pump stall pressure. A hydraulic compressor system according to any one of claims 1 to 7.

9. It also features multiple liquid lines, Each liquid line is configured to connect a hydraulic compression tank to one or more of the one or more pumps, Each liquid line includes at least two shut-off valves. Each liquid line is configured to connect each compression tank to one or more of the one or more pumps in a closed circuit. Each liquid line includes a forward shut-off valve and a return shut-off valve. When the hydraulic compression tank is configured to operate in the compression stroke, the forward shutoff valve is open and the return shutoff valve is closed. When the hydraulic compression tank is configured to operate in the return stroke, the forward shutoff valve is closed and the return shutoff valve is open. A hydraulic compressor system according to any one of claims 1 to 8.

10. The server system is further equipped with The shut-off valve is controlled by a control system. The control system is configured to open and close the shut-off valve based on data received from the sensor. The hydraulic compressor system according to claim 9.

11. The aforementioned sensor system, A pressure sensor is positioned to measure the pressure of the liquid in the inflatable bladder within each hydraulic compression chamber, A pressure sensor is positioned to measure the pressure inside the gas storage tank, A hydraulic compressor system according to claim 10, comprising:

12. The aforementioned sensor system, A flow meter fluidly connected to the expandable bladder in each hydraulic compression chamber, A pressure sensor is positioned to measure the pressure inside the gas storage tank, A hydraulic compressor system according to claim 10 or 11, comprising:

13. The aforementioned sensor is A flow meter fluidically connected to the pump discharge side, A pressure sensor is fluidly connected to the storage tank, Composed of, If the gas intake pressure is constant, no other sensors are needed. A hydraulic compressor system according to any one of claims 10 to 12.

14. The control system is a. Before the compression stroke is initiated, data corresponding to the pressure of the liquid in the expandable bladder is received, b. After the compression stroke has started, receive data corresponding to the pressure of the liquid in the expandable bladder, c. Calculate the compression ratio (Vc / Vo), d. Determine whether the compression ratio has reached its maximum value. e. When the compression ratio reaches its maximum value, the shut-off valve is switched from open to closed or from closed to open. It is configured to A hydraulic compressor system according to any one of claims 10 to 13.

15. The control system is configured to switch the shut-off valve from open to closed or from closed to open when the pump reaches a stall condition defined by the pump current. A hydraulic compressor system according to any one of claims 11 to 15.

16. The automatic switching of the system from the forward compression cycle of the first compression tank to the forward compression cycle of the second compression tank and the return stroke of the first compression tank occurs with a time difference between the opening operation of the second forward valve and the first reverse valve and the closing operation of the first forward valve and the second reverse valve. The aforementioned time difference is in the range of 1 / 10 to 1 / 2 of the time required for the shut-off valve to fully open. A hydraulic compressor system according to any one of claims 11 to 16.

17. The system includes a pair of pumps, each consisting of two pumps, which are connected in parallel and configured to operate as a single unit. Of the pair of pumps mentioned above, The first pump has a high flow rate capacity but a low pressure limit. The second pump has a low flow rate capacity but a high pressure limit. The hydraulic compressor system according to claim 1.

18. The pump includes a variable speed pump, The pump speed is adjusted to decrease towards the end of the compression stroke, thereby reducing the liquid flow rate and enabling a smooth switch from one compression tank to another when an automatically controlled shut-off valve opens and closes. The hydraulic compressor system according to claim 1.

19. The aforementioned plurality of compression tanks include three or more tanks, Each tank is connected to a dedicated passage through which liquid is supplied and gas is forced out. The aforementioned dedicated passageway is A pressure sensor for measuring liquid pressure or a flow meter for measuring liquid flow rate, A pair of shut-off valves that control the flow of liquid from the pump to the compression tank during the compression stroke and control the flow of liquid from the compression tank to the pump during the return stroke, Equipped with, The operating timing of the shut-off valves corresponding to each of the multiple tanks is adjusted so that one or more of the pumps do not reach a stall condition. The hydraulic compressor system according to claim 1.

20. A method for compressing a gas, wherein the method is a. Step of providing a first compression tank. The first compression tank includes, i. An inflatable bladder defining a bladder space, the inflatable bladder storing a liquid within the inflatable bladder space, ii. A tank space containing compressible gas, located outside the inflatable bladder, iii. Liquid input section and, iv. Gas port and, Equipped with, The aforementioned method further, v. The step of connecting the gas port of the first compression tank to a gas storage tank via a gas line, vi. The step of connecting the liquid input section of the first compression tank to the first liquid line, b. The step of operating the first compression tank in either a compression stroke or a return stroke, Includes, The step of operating the first compression tank with the compression stroke is: i. A step of pumping the liquid through the first liquid line into the expandable bladder space in the first compression tank to compress the gas in the tank space of the first compression tank, thereby causing the expandable bladder of the first compression tank to expand into the tank space, ii. The steps of discharging the gas from the tank space of the first compression tank through the gas port and recovering the gas in the gas storage tank, iii. The step of further compressing the gas in the gas storage tank, Includes, c. The step of operating the first compression tank in the return stroke is: i. The step of pumping liquid out of the expandable bladder space in the first compression tank via the first liquid line so that the expandable bladder of the first compression tank contracts, thereby increasing the volume of the tank space in the first compression tank, ii. A step of filling the tank space of the first compression tank with gas from a low-pressure gas source via the gas port, A method that includes this.

21. The aforementioned method, a. Step of providing a second compression tank. The second compression tank includes, i. An inflatable bladder defining a bladder space, the inflatable bladder storing a liquid within the inflatable bladder space, ii. A tank space containing compressible gas, located outside the inflatable bladder, iii. Liquid input section and, iv. Gas port and, Equipped with, The aforementioned method further, b. A step of connecting the gas port of the second compression tank to a gas storage tank via a gas line, wherein the first compression tank and the second compression tank may be connected to the same gas storage tank or to different gas storage tanks. c. A step of connecting the liquid input section of the second compression tank to the second liquid line, wherein the first liquid line and the second liquid line are in fluidic communication. d. The steps of operating the first compression tank in a compression stroke and the second compression tank in a return stroke, Includes, The aforementioned step is, e. A step in which liquid is pumped from the expandable bladder space of the second compression tank to the expandable bladder space of the first compression tank, thereby compressing the gas in the tank space of the first compression tank, causing the expandable bladder of the second compression tank to contract and the expandable bladder of the first compression tank to expand, f. The steps of discharging the gas from the tank space of the first compression tank through the gas port of the first hydraulic chamber and recovering the gas in the gas storage tank, g. A step of filling the tank space of the second compression tank with gas from a low-pressure gas source through the gas port of the second hydraulic chamber, h. A step of further compressing the gas in the gas storage tank, The method according to claim 20, including the method described in claim 20.

22. The aforementioned method further, a. A step of determining that the compression stroke of the first compression tank has been completed and / or that the return stroke of the second compression tank has been completed, b. A step of switching the operation of the first and second compression tanks, operating the second compression tank in a compression stroke, and operating the first compression tank in a return stroke, Includes, The aforementioned step is, The process involves pumping liquid from the expandable bladder space of the first compression tank to the expandable bladder space of the second compression tank, thereby compressing the gas in the tank space of the second compression tank, causing the expandable bladder of the first compression tank to contract and the expandable bladder of the second compression tank to expand. c. The steps of discharging the gas from the tank space of the second compression tank through the gas port of the second hydraulic chamber and recovering the gas in the gas storage tank, d. A step of filling the tank space of the first compression tank with gas from a low-pressure gas source through the gas port of the second hydraulic chamber, e. A step of further compressing the gas in the gas storage tank, The method according to claim 21, including the method described in claim 21.

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