Electrolytic cell system with gas pressure balancing method and pressure balancing valve system

Abstract

In the gas pressure equilibrium method in an electrolytic cell system, a predefined pressure difference between the pressure in the oxygen gas separation tank and the pressure in the hydrogen gas separation tank is maintained by the controlled release of gas through the oxygen back pressure valve and the hydrogen back pressure valve. In the first step, a predefined, calibrated pilot gas pressure is generated for each of the oxygen back pressure valve and the hydrogen back pressure valve. In the second step, the predefined, calibrated pilot gas pressure is sent to the respective back pressure valves. In the third step, if the gas pressure in the hydrogen separation tank and the oxygen separation tank exceeds the predefined, calibrated pilot pressure in the respective pilot gas flow, the hydrogen gas and oxygen gas are released.

Description

Technical Field

[0001] The present invention relates to a gas pressure balancing method in an electrolytic cell system. The present invention further relates to an electrolytic cell system equipped with a pressure balancing valve system.

Background Art

[0002] In an electrolytic cell system such as a pressurized alkaline water electrolytic cell having a cell stack and a product separation tank for product depletion of the electrolyte drawn from the cell stack, it is a well-known problem that it is difficult to maintain the pressure balance in the separation tanks of hydrogen gas and oxygen gas. According to the present invention, an improved or at least alternative method and system are provided for ensuring a predefined pressure balance in two product tanks. In the following description, the gases released by the electrolysis of water, namely hydrogen and oxygen, are referred to as product gases. First, the gases are more or less incorporated into the caustic alkali solution stream collected from the electrolytic cell stack, but the gases are released from the caustic alkali solution in the gas / caustic alkali solution separation tank.

Summary of the Invention

[0003] According to a first aspect, the object of the present invention may be obtained by a gas pressure balancing method in an electrolytic cell system, whereby a predefined pressure difference between the pressures in an oxygen gas separation tank and a hydrogen gas separation tank connected to the output side of a water electrolytic cell stack or each of a plurality of stacks is maintained by a controlled release of gas through an oxygen backpressure valve and a hydrogen backpressure valve arranged in fluid connection with the respective separation tanks.

[0004] According to this aspect of the present invention, in the first step, a predefined, calibrated pilot gas pressure is generated for each of the oxygen back pressure valve and the hydrogen back pressure valve by a feed-and-bleed valve system in the pilot gas flow; in the second step, the predefined, calibrated pilot gas pressure is sent to the respective back pressure valves; and in the third step, if the gas pressure in the hydrogen separation tank exceeds the predefined, calibrated pilot pressure in the first pilot gas flow, hydrogen is released from the hydrogen gas separation tank via the hydrogen back pressure valve; and if the gas pressure in the oxygen gas separation tank exceeds the predefined, calibrated pilot pressure in the second pilot gas flow, oxygen is released from the oxygen gas separation tank via the oxygen back pressure valve.

[0005] This method and system allows for very rapid and precise adjustment of the pressure in two separation tanks, and a precise pressure difference, and in some cases zero pressure difference, can be maintained between the tanks. It also allows for rapid adaptation to the demands of changes in the pressure difference. This is mainly due to the fact that when the gas release valve is induced by pilot gas pressure, there is very little mass that needs to be moved or accelerated to change the setting of the gas release valve. This works particularly well when a dome-loaded valve is used as the gas release valve in this configuration, as only the pilot gas and the membrane need to be moved to change the setting of the valve, both of which operate with very little friction and have minimal mass.

[0006] In a further embodiment, the feed-and-bleed valve system includes a bleed valve that bleeds off pilot gas to ambient pressure or a similarly low pressure through a bleed orifice, and the feed-and-bleed valve system further feeds pilot gas to the bleed valve through an adjustable feed valve so that a pilot gas pressure of a desired pressure is achieved between the bleed valve and the feed valve by adjusting the feed valve opening.

[0007] This configuration ensures accurate pilot gas pressure and keeps reaction time very short, resulting in a very short time lag between the occurrence of new input values, such as pressure value signals from pressure or pressure difference measurements in one or both isolation tanks, and the pilot gas pressure correction being brought between the feed valve and the bleed valve.

[0008] In one embodiment, a first pilot gas flow and a second pilot gas flow are generated by supplying pressurized pilot gas to a gas pump, and a pressurized booster gas, such as pressurized air, is supplied to a motor, which in turn drives the gas pump, thereby increasing the pressure of the pressurized pilot gas flow. Furthermore, the pilot gas flow is split into a first pilot gas flow and a second pilot gas flow, both having a pressure sufficiently higher than the pressure required to close the back pressure valves for the hydrogen gas separation tank and the oxygen gas separation tank.

[0009] The pressure required for the pilot gas flow to stop the generated gas must be higher than the pressure in the respective separation tanks, due to the properties of the oxygen and hydrogen back pressure valves. This higher pressure can be generated in a local booster pump that receives the pilot gas at a predefined discharge pressure and further pressurizes it to the required pilot gas operating pressure. This can be beneficial when a pressure level not typically available for industrial gases is required to control the back pressure valve. It is preferable to have a booster pump that is readily available and driven by pressurized air. When an inert or partially inert gas, such as nitrogen gas, is used as the pilot gas, only one booster pump is required, which can branch off the well-pressurized pilot gas to each of two different feed-and-bleed valve configurations.

[0010] In a further embodiment of this method, a first pilot gas flow is drawn from an oxygen tube, a second pilot gas flow is drawn from a hydrogen tube, and both pilot gas flows are boosted by their respective generating gas pumps, which are driven by motors powered by a supply of pressurized air.

[0011] This embodiment is highly desirable because it allows each generated gas to be used as its respective pilot gas, ensuring that hydrogen is used as the pilot gas in a dome-loaded hydrogen back pressure valve and oxygen is used as the pilot gas in a dome-loaded oxygen back pressure valve. In this way, an improvement in safety for possible mixtures of oxygen and hydrogen gases is achieved, and the use of a third gas such as nitrogen is omitted. Two generated gas booster pumps are preferably driven by motors powered by pressurized atmosphere.

[0012] In a further embodiment of this method, the gas flow continuously leaking from the bleed valve of the feed-and-bleed valve system is sent to each of its gas quality control measuring devices, and an auxiliary generated gas supply valve is located in the auxiliary gas pipe between each of the generated gas pipes and each gas quality control measuring device, thereby being induced by a signal drawn from a fluid flow measuring device located between the bleed valve and each gas receiver.

[0013] This embodiment ensures that the gas leaking from the bleed valve is used for the gas quality meter. The gas quality meter is a safety requirement, and therefore, for this purpose, a gas flow must be provided, and if the generated gas is used as pilot gas, bleed-off from the bleed valve may also be used for this purpose. To ensure that the gas quality meter functions even when the gas flow is low or the pressure is low, additional generated gas is provided by bypassing the feed-and-bleed valve system.

[0014] In a second embodiment, the object of the present invention may also be obtained by an electrolytic cell system having a pressure balancing valve system, wherein the oxygen separation tank and the hydrogen separation tank are provided with their respective tubular connections to each side of the separation diaphragm in one or more electrolytic cell stacks, and oxygen back pressure valves and hydrogen back pressure valves coupled to the respective separation tanks via piping are provided, adapted to open for controlled release of oxygen-generated gases and hydrogen-generated gases at a predetermined product gas separation tank pressure.

[0015] According to this aspect of the present invention, a back pressure valve is adapted to open to a predetermined pilot gas pressure for the release of a generated gas, and further, a feed-and-bleed valve system is adapted to generate a predetermined pressure from a high-pressure gas in a pipe interconnecting a feed valve and a bleed valve, the bleed valve is adapted to deliver a bleed-off of pilot gas to a lower pressure, and the feed valve is adapted to adjust to deliver pilot gas to the pipe interconnecting the feed valve and the bleed valve such that a desired predetermined pressure is maintained in the pipe between the feed valve and the bleed valve.

[0016] The feed valve may preferably be regulated by a PLC setpoint generator, which, among other things, receives a signal indicating the pressure in the gas separation tank being regulated and / or a measured value of the pressure difference between the two separation tanks, as well as the actual pressure in the tubing between the bleed valve and the feed valve, and periodically calculates a corrected setting for the feed valve opening. In this way, the rapid and appropriate generation of a calibrated pilot gas pressure in the tubing between the feed valve and the bleed valve is ensured.

[0017] The electrolytic cell system further comprises a pilot gas supply source connected to a gas pump, the pump being adapted to act as a booster to further pressurize the pilot gas flow, thereby the pilot gas pump being adapted to be driven by a motor adapted to receive its driving energy from a pressurized atmospheric supply source.

[0018] When a local pilot gas source such as pressurized nitrogen is used, an increase in nitrogen pressure may be required. Due to the nature of electrolytic cell plants with oxygen and hydrogen gases under pressurization, it is preferable to use a compression method that relies on driving pressurized air, which is less hazardous, to eliminate the risks of electric sparks, electric heating, and similar problems. Furthermore, the flow of depressurized air that must inevitably be discharged from such a motor can be used to ensure air renewal in parts of the plant where the air exchange rate is essential. Preferably, the motor is supplied with a drive gas flow having a pressure lower than the pressure of the high-pressure pilot gas flow delivered by the pump.

[0019] In one embodiment of the present invention, the feed-and-bleed valve arrangement is configured such that the generated gases for the first and second pilot gas flows are supplied to the feed-and-bleed valve configuration. The first pilot gas flow originates from an oxygen tube and is connected to the feed-and-bleed valve system via a gas booster pump, and the second pilot gas flow originates from a hydrogen tube and is connected to the feed-and-bleed valve system via a further gas booster pump.

[0020] To directly use the generated gas stream as a pilot gas to control the opening and closing of the hydrogen and oxygen release valves, the generated gas pressure in the pilot gas stream must be increased, and therefore the pilot gas stream is pressurized in this case. Preferably, a compressed air-driven pump is used to pressurize the two pilot gas streams drawn from each of its generated gas streams. When using hydrogen to adjust the hydrogen back pressure valve and oxygen to adjust the oxygen back pressure valve, there is no risk of the hydrogen and oxygen gases mixing.

[0021] In one embodiment of the present invention, the back pressure valve is a dome-loaded valve, and pilot pressure is supplied to one side of the membrane, and the generated gas side of the membrane is adapted to abut two sets of orifices, namely, a first set of orifices that are in fluid communication with the aforementioned product separation tank, and a second set of orifices that are in communication with the receptors for each generated gas.

[0022] When the membrane contacts the two sets of orifices, the generated gas is prevented from moving through the valve, and when the membrane rises due to the higher pressure on its generated gas side, the valve opens and the gas passes from the first set of orifices to the second set of orifices. The valve can be adequately constructed from orifices arranged in concentric circles, with an inlet orifice located in the first semicircle and an outlet orifice in the second semicircle on the opposite side of the same circle. This arrangement allows for gradual opening and closing of the valve, which ensures that the regulating characteristics are the same regardless of the opening.

[0023] In one embodiment, a gas quality control measuring device is positioned in the gas outlet pipe between the bleed valve and the generated gas receiver, and an auxiliary generated gas supply valve is positioned in the auxiliary gas pipe between each of the generated gas pipes and each gas quality control measuring device, so that this auxiliary generated gas supply valve is guided by a signal drawn from a fluid flow rate measuring device positioned between the bleed valve and each gas receiver at the far end of the gas outlet pipe.

[0024] The auxiliary gas pipe ensures reliable data is obtained even when the flow rate through the bleed valve is too low to guarantee reliable gas quality measurements. During steady-state generation, the auxiliary generation gas supply valve is closed, and sufficient gas flows out through the bleed valve.

[0025] In the context of this invention, the gases released by the electrolysis of water, namely hydrogen and oxygen, are referred to as product gases.

[0026] When used herein, the terms “to be equipped / to be equipped / to be equipped” are to be interpreted as specifying the presence of the described feature, integer, step, or component, but it should be emphasized that this does not exclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0027] The present invention will be described in more detail below with reference to the embodiments shown in the accompanying drawings. It should be emphasized that the embodiments shown are for illustrative purposes only and should not be used to limit the scope of the present invention.

Brief Description of the Drawings

[0028] [Figure 1] It is a schematic diagram of a system according to the present invention. [Figure 2] It is a schematic diagram of a further system according to the present invention. [Figure 3] It is a schematic diagram of a system to which oxygen pressure is introduced. [Figure 4] It shows a gas backpressure valve. [Figure 5] It is a schematic diagram of a dome-loaded pilot gas pressure regulating valve with an accompanying feed-and-bleed valve system. [Figure 6] It is a schematic diagram of the reuse of excess gas from a bleed valve in a gas quality monitoring device. [Figure 7] It is a schematic diagram of a system comprising generated gas boosters 47A, 47B adapted to increase the pressure of the generated gas used as pilot gas.

Modes for Carrying Out the Invention

[0029] Various exemplary and non-limiting embodiments relating to both the structure and the method of operation, together with their additional objectives and advantages, will be best understood from the following description of specific exemplary and non-limiting embodiments when read in conjunction with the accompanying drawings.

[0030] The verbs "comprise" and "include" are used herein as open limitations that do not exclude or require the presence of features not recited. The features recited in the dependent claims can be freely combined with each other unless otherwise specified. Further, throughout this specification it should be understood that the use of "a" or "an", i.e., the singular, does not exclude the plural.

[0031] Electrolytic cell and gas release valve The system disclosed in Figure 1 includes supply sources such as gas separation tanks 1 and 2 for each product gas from the electrolytic cell stack. Each supply source, gas separation tank 1 or gas separation tank 2, is indicated by a circle in the figure and comprises gas / electrolyte separation tanks 1 and 2. The hydrogen gas separation tank 2 receives a mixture of cathodic acid and hydrogen (product) gas from the first side 19 of the separation diaphragm 17 of one or more stacks 3 via a cathodic acid and hydrogen gas line 37.

[0032] Oxygen separation tank 1 receives the anolyte and oxygen gas (product) mixture from the second side 20 of one or more separation diaphragms 17 of the same stack 3 or multiple stacks via the anolyte and oxygen gas line 36. Each of oxygen and hydrogen separation tanks 1 and 2 can receive the gas / electrolyte mixture from one or more electrolytic cell stacks 3. Typically, stack 3 comprises multiple pairs of electrolytic chambers, each such pair separated by a diaphragm 17, but for simplicity, only one such pair of chambers is shown in Figure 1.

[0033] In the example shown in Figure 1, the depleted anolyte in the anolyte pump backline 34 and the depleted cathodeite in the cathodeite pump backline 35 reach each side of one or more diaphragms 17, completely separating the anolyte and cathodeite flow circuits.

[0034] In other electrolytic cell systems for producing hydrogen from water, the anosolite and cathode liquid flows are mixed in the cathode and anosol chambers of the stack before the electrolyte is introduced.

[0035] Pumps and heat exchangers in the return pipe to the stack, although not shown in Figure 1, may be adequately provided to increase fluid flow and ensure temperature control of the fluid introduced into the stack.

[0036] The pressures in the two tanks 1 and 2 should be maintained in equilibrium to ensure that the pressures on each side of the diaphragm 17 in the stack 3 are similar and do not deviate from each other beyond predetermined limits. This is achieved by the controlled release of the generated gases, namely oxygen and hydrogen, through controlled back pressure valves 4 and 5 located in gas tubes adapted to deliver the generated gases to their receivers 45 and 46. The hydrogen tube 38 ensures passage from the hydrogen gas separation tank 2 and the hydrogen back pressure valve 4, and the oxygen tube 39 ensures passage from the oxygen gas separation tank 1 and the oxygen back pressure valve 5.

[0037] Each of the back pressure valves 4 and 5 is controlled by a dedicated pilot gas having its own pilot gas pressure.

[0038] Dome-loaded valve In one embodiment, the back pressure valves 4, 5 are dome-loaded valves 22, and pilot pressure is supplied to the closing pressure side 16 of the membrane 23, and the generated gas side 18 of the membrane 23 is adapted to abut two sets of orifices, namely, a first set of orifices 24 that are in fluid communication with the product separation tank described above, and a second set of orifices 25 that are in communication with receivers (not shown) for each generated gas.

[0039] When the pressure on the membrane's closing pressure side 16 is higher than the pressure on the generated gas side 18, the membrane 23 is pressurized toward the orifices 24 and 25, so that the two sets of orifices are closed, and vice versa. When the pilot pressure is lower than the generated pressure, the membrane 23 separates from the two sets of orifices 24 and 25, as shown in Figure 5, and the gas passes through valve 22 from the connected gas separation tanks 1 and 2 to the receiving containers (not shown).

[0040] The dome-loaded valve 22 is extremely fast because both internal friction and moving mass are minimal during opening and closing. Furthermore, this type of valve tends to maintain consistent dynamic characteristics throughout its entire opening range.

[0041] Area-exchangeable piston valve In a further embodiment, the back pressure valves 4 and 5 schematically shown in Figure 4 are piston valve members 21. The valve member 21 has a piston 26 having a first gas pressure impact region A1 at a first end 27 for moving the piston 26 in a first direction, and another (second) gas pressure impact region A2 at a second end 28 for moving the piston in a second opposite direction.

[0042] In the valve design disclosed in Figure 4, the first gas pressure shock region A1 is adapted to fluidly communicate with the pilot gas, and the second gas shock region A2 is adapted to fill the generated gas with its generated gas pressure.

[0043] When the generated gas pressure rises to a level that allows the piston to move in a second direction (upward in Figure 4), the opening 29 is positioned so that the generated gas leaks out through it to the outlet. The outlet is to be connected to a generated gas receiver (not shown). The pressure in the pilot gas maintains the valve in the closed position if the quotient of generated gas pressure / pilot gas pressure is greater than the quotient of A1 / A2.

[0044] The difference between the A1 and A2 areas allows the valve to close even when the pilot gas pressure is lower than the generated gas pressure.

[0045] In one embodiment, as shown in Figure 4, the piston 26 is fitted to move within the cylinder 30 and includes a piston ring or O-ring 31, etc., which forms a gasket between the piston 26 and the cylinder 30 at both A1 and A2 ends of the piston 26.

[0046] Other types of pistons, such as bellows-sealed pistons and cylinder pairs, can be used to reduce friction and inertia, and may increase the agility of the valve 21.

[0047] The piston 26 may be made from a lightweight material such as a polymer and / or may be hollow so as to ensure that the movable mass remains as small as possible to ensure good opening and closing characteristics of the valve.

[0048] Gas pressure equilibrium method As shown in Figures 1, 2, and 3, the feed-and-bleed valve system 12 is configured to supply a predefined pilot gas pressure to control the opening pressure of either the dome-loaded valve 22 or the piston valve member 21.

[0049] When a dome-loaded valve 22 is used, the pilot gas pressure must be higher than the pressure in the generated gas in order to move the membrane 23 toward the two sets of orifices 24, 25. To generate the required pressure in the first and second pilot gas flows, the pilot gas flows are generated by increasing the pressure of a pre-pressurized nitrogen gas flow 9.

[0050] As shown in Figure 1, this is done by feeding a pre-pressurized nitrogen gas stream 9 through a gas pump 8 driven by a motor 11, such that the nitrogen gas stream 9 exits the pump at a pressure higher than its inlet pressure.

[0051] In the embodiment shown in Figure 1, the motor 11 is driven by the flow of compressed air 10. A gear system or other mechanical replacement between the compressed air-driven motor 11 and the gas pump enables the pump 8 to deliver pilot nitrogen gas at a pressure far exceeding the maximum pressure of any of the generated gases.

[0052] Any inert gas or gas composition other than nitrogen may be used as the pilot gas.

[0053] As shown in Figure 1, the pressurized nitrogen gas is divided into a first pilot gas flow 6 and a second pilot gas flow 7.

[0054] PLC set point generation The feed-and-bleed valve system 12 is positioned to reduce the pressure of the pilot gas flows 6, 7 according to the PLC generation setpoint for the controlled release of the generated gases 38, 39.

[0055] The setpoints for the hydrogen and oxygen back pressure valves 4 and 5 are derived from pressure or pressure difference signals 40 and 41 resulting from pressure measurements of the generated gas flows 38 and 39, as shown in Figures 1 and 2. The setpoints are determined under the guidance of PLC discharge pressure setpoint generators 32 and 33.

[0056] The PLC setpoint generators 32 and 33 are programmable devices that can take into account a range of parameters, particularly differential and integral signals, such as the system's time constant, the power supplied to the electrolytic cell, and signals derived from the time-dependent pressure change of the measured input pressure signal.

[0057] In Figure 5, the setpoint generators 32 and 33 control the opening of the pilot gas feed valve 14 based on the calculated setpoint and the pressure P between the feed valve 14 and the bleed valve 13. The setpoint may also be calculated from the pressure in the gas separation tank from which the generated gas is released, in which case the pressure in the other gas separation tank is induced by the differential pressure between the two tanks. This is shown in Figures 1 and 2. In addition to Figure 1, in Figure 2 as well, the gas pressure signal 40 from the pressure in the hydrogen tube 38, which is also the magnitude of the pressure in the hydrogen release tank 2, is supplied by the PLC hydrogen release pressure setpoint generator, which then calculates the setpoint for the feed valve 14. Furthermore, the pressure difference signal 41 is supplied by the PLC oxygen release pressure setpoint generator 33 so that the setpoint generator 33 calculates the setpoint for the feed valve 14 to control the release of oxygen through the oxygen back pressure valve 5. In this way, the pressure in the oxygen tube 39, which is also the magnitude of the pressure in the oxygen gas separation tank 1, can be induced to follow the pressure in the hydrogen gas separation tank or to deviate from the pressure in the hydrogen gas separation tank in a predetermined manner.

[0058] In Figure 3, a similar system is shown, where the pressure in the oxygen tank 1 via the pressure signal 40.1 from tube 39 is used to induce the release of oxygen, while the differential pressure signal 41 between the pressure in the hydrogen separation tank and the pressure in the oxygen separation tank induces the release of hydrogen.

[0059] Feed and bleed valve system The settings from the PLC device are used in the feed-and-bleed valve system 12 to adjust the settings of the feed valve 14, as shown in Figures 1, 2, 3, and 6.

[0060] As a result, the increase in pilot gas fed into pipe 48 through feed valve 14 causes an increase in calibrated pressures 6.1 and 7.1 sent from feed-and-bleed valve system 12 to back pressure valves 4 and 5.

[0061] The pressure monitor P monitors the pressure in the pipe 48 between the feed valve 14 and the bleed valve, as shown in Figure 5. This allows the difference between the setpoint calculated in PLC 32 or 33 and the calibrated pressure calculated here to be determined, and a corresponding adjustment operation signal is transmitted to the adjusted feed valve 14.

[0062] The indicated bleed valve 13 may be an adjustable or non-adjustable valve. If valve 13 is an adjustable valve, the bleed flow may be increased or decreased as needed. If the need to adjust the settings of the back pressure valves 4, 5 is very limited, such as in a hot standby state, then very little gas bleed is required to maintain the settings of the back pressure valves 4, 5, and thereafter the bleed rate can be kept very low. In other types of settings where rapid opening and closing of the back pressure valves is required, a higher bleed rate is beneficial as it allows for a faster pressure drop in the pipe segments 7.1, 6.1 between the feed and bleed valves.

[0063] Pilot gas regulating back pressure piston valve In the embodiments of FIGS. 2, 3, 6, and 7, the pilot gas of the hydrogen release valve 4 is hydrogen drawn from the hydrogen separation tank, and the pilot gas of the oxygen release valve 5 is oxygen drawn from the oxygen separation tank. In these cases, the pilot gas is fed through the feed-and-bleed valve system 12 to raise the pilot gas pressure so as to cause a calibrated output pilot gas pressure sufficient to close the dome-loaded valve 22, or alternatively, backpressure valves 4, 5 that close at a pilot gas pressure less than the backpressure in pipes 38, 39 need to be used respectively.

[0064] When the rise of the pilot gas, which is also the product gas here, is used, pressurized air may be used in the motor set, and each of the hydrogen product gas booster pump 47A and the oxygen product gas booster pump 47B, which operate in the gas supplied from the gas separation tank to control each of the dome-loaded valves, is driven. This is shown in FIG. 7. In this way, the valve controlling the outflow of hydrogen is filled with hydrogen for the control of the membrane 23, and subsequently, the valve controlling the outflow of oxygen is filled with oxygen for the control of the membrane 23. Improved safety is achieved in that the risk of mixing of oxygen and hydrogen is minimized.

[0065] It is also possible to introduce a pressure drop into the oxygen pipe and the hydrogen pipes 38, 39 between the pilot gas branches 6, 7 and the backpressure regulators 4, 5, thereby ensuring that there is always a higher pressure at the branches 6, 7 than at the backpressure regulators 4, 5. However, this may lead to a smaller output pressure at the receiver 45, which is not desirable.

[0066] Alternatively, as shown in FIG. 4, a backpressure regulating piston valve 21 may be used. The closing operation region A1 of the first end 27 of the backpressure valve piston 26 is filled with the pilot gas pressure and is somewhat larger than the opening operation region A2 of the second end 28 of the backpressure valve piston 26 filled with the pressure in each separation tank. The release valve piston 26 is in accordance with the following formula A2 × product gas pressure < A1 × pilot gas pressure If this condition is met, the opening 29 that blocks the generated gas flow is adjusted to accommodate the condition.

[0067] Thus, A1 is somewhat larger than A2, and therefore, even when the calculated pressure loss through the feed-and-bleed valve system 12 for generating the correct pilot gas pressure is adjusted, it can always provide the pressure necessary to close the valve 21 using the generated gas as pilot gas and pilot pressure, and the generated gas pressure that has not been boosted. This is shown in Figure 6, where there is no boosting of the pilot gas flows 6, 7. Preferably, 1.1 × A2 ≤ A1 ≤ 2 × A2 That is the case.

[0068] By ensuring that A1 is between 1.1 and 2 times A2, it becomes possible to always close the valve, resulting in good accuracy.

[0069] If better accuracy and dynamic performance are desired, 1.05 × A2 ≤ A1 ≤ 1.2 × A2 It is preferable.

[0070] By making A1 1.05 times larger than A2 and less than 1.2 times larger than A2, and bringing it even closer to the area of ​​A2, even better dynamic performance can be ensured.

[0071] In Figures 2 and 3, either a valve with a pilot gas booster or a valve with a specific back pressure valve piston 26 is used.

[0072] Reuse of gas leaked through the bleed valve The gas flow continuously leaks from the bleed valve 13 of the feed-and-bleed valve system 12 described above when the back pressure valve is adjusted. However, if the generated gas is used as a pilot gas, this leaked gas flow may be used in a gas quality control measuring device 15 for each of the two leaked gas flows. This is disclosed in Figure 6. This ensures that the leaked gas is used to generate necessary information regarding the quality of the generated gas or to generate safety data such as the percentage of H2 in the O2 gas and the percentage of O2 in the generated H2 gas.

[0073] The minimum flow rate through the gas quality control measuring device 15 is required to obtain reliable gas quality monitoring data; therefore, the auxiliary generated gas supply valve 42 is located in the auxiliary gas pipe 44 between the generated gas pipes 38, 39 and the gas quality control measuring device 15. This valve is induced by a signal drawn from the fluid flow rate measuring device 43 so that the generated gas supply valve 42 opens when the flow rate measuring device 43 records that the flow rate through the gas quality control measuring device 15 is too low.

[0074] Hydrogen control signal derived from hydrogen tube pressure In Figure 1, the pressure in the separation tank 2 is used via a pressure signal 40 to adjust the hydrogen back pressure valve 4, so the pressure in the hydrogen tube 38 is the same as the pressure inside the hydrogen. In this embodiment, a differential pressure signal 41 (which is the pressure difference between the pressures in the two separation tanks 2, 1) is used to induce the release of oxygen via the oxygen back pressure valve. In this embodiment, the feed-and-bleed valve system 12 receives pilot gas flows 6, 7 in the form of nitrogen gas pressurized to a pressure far exceeding the maximum allowable pressure for the generated gas flow.

[0075] This nitrogen gas flow may be adequately replaced by a pressurized generated gas flow, or it may be replaced by a generated gas flow at the pressure in the respective separation tanks 1 and 2, in combination with a back pressure valve member 21 having two different gas operating regions A1 and A2 as disclosed in Figure 4 and described above.

[0076] It should be noted that the drawings and the above description provide a simple and schematic representation of exemplary embodiments. Those skilled in the art should be familiar with these details, and many specific mechanical details are omitted as they would only unnecessarily complicate this description. [Explanation of Symbols]

[0077] 1. Oxygen gas separation tank 2. Hydrogen gas separation tank 3. Water electrolytic cell stack 4. Hydrogen back pressure valve 5. Oxygen back pressure valve 6. First pilot gas flow (O2) 6.1 First Calibrated Pilot Pressure 7. Second pilot gas flow (H2) 7.1 Second Calibrated Pilot Pressure 8. Gas Booster Pump 9. Pressurized nitrogen 10 Pressurized atmosphere 11 Motor 12 Feed and Bleed Valve Systems 13 Bleed valve 14 Feed valve 15. Gas quality control and measurement device 16. Membrane closure pressure side 17 Diaphragm 18. The generated gas side of the membrane 19 The first side of one or more diaphragms 20 The second side of one or more diaphragms 21 Piston valve member 22 Dome-loaded valve 23 membrane 24. Orifice of the first set 25. Orifice of the second set 26 Back pressure valve piston 27 First end 28 Second end 29 Opening 30 cylinders 31 Piston Rings 32 PLC Hydrogen Release Pressure Setpoint Generator 33 PLC Oxygen Release Pressure Setpoint Generator 34. Anode liquid pump back line 35 Cathode Liquid Pump Backline 36. Anode liquid and oxygen gas lines 37. Cathodeliquid and hydrogen gas lines 38 Hydrogen tubes 39. Oxygen tube 40 Pressure signal, hydrogen 40.1 Pressure signal, oxygen 41 Pressure difference signal 42. Gas supply valve 43 Fluid flow measurement device 44. Supply of auxiliary product gases 45. Gas Receptor 46 Atmospheric receptors 47A Hydrogen-generating gas booster pump 47B Oxygen Generating Gas Booster Pump 48. Pipes connecting the feed valve and the bleed valve. A1 First gas pressure shock area / closing operation area A2 Second gas pressure impact area / opening operation area

Claims

1. A gas pressure equilibrium method in an electrolytic cell system, wherein an oxygen gas separation tank (1) and a hydrogen gas separation tank (2) are connected to the output sides of a water electrolytic cell stack (3) or a plurality of water electrolytic cell stacks (3), and by this method, a predetermined pressure difference between the pressure in the oxygen gas separation tank (1) and the pressure in the hydrogen gas separation tank (2) is maintained by the controlled release of gas through oxygen back pressure valves (5) and hydrogen back pressure valves (4) which are fluidly connected to the respective separation tanks (1, 2). - For each of the oxygen back pressure valve (5) and the hydrogen back pressure valve (4), a predefined, calibrated pilot gas pressure (6.1, 7.1) is generated by the feed-and-bleed valve system (12) in the pilot gas flow (6, 7). - The pilot gas at the predefined, calibrated pilot gas pressure (6.1, 7.1) is sent to the respective back pressure valves (4, 5). A gas pressure balancing method comprising: - If the gas pressure in the hydrogen separation tank (2) exceeds the predefined calibrated pilot gas pressure (7.1), hydrogen is released from the hydrogen gas separation tank (2) via the hydrogen back pressure valve (4); and if the gas pressure in the oxygen gas separation tank (1) exceeds the predefined calibrated pilot gas pressure (6.1), oxygen is released from the oxygen gas separation tank (1) via the oxygen back pressure valve (5).

2. The gas pressure balancing method according to claim 1, wherein the feed-and-bleed valve system (12) comprises a bleed valve (13) at ambient pressure or a similarly low pressure, thereby the feed-and-bleed valve system (12) further feeds pilot gas to the bleed valve (13) via an adjustable feed valve (14), thereby achieving the desired calibrated pressure (7.1, 6.1) of pilot gas in the pipe (48) between the bleed valve (13) and the feed valve (14) by adjusting the opening of the feed valve (14).

3. The gas pressure balancing method according to claim 1 or 2, wherein the two pilot gas flows (6, 7) are generated by supplying pressurized pilot gas to a gas pump (8), supplying pressurized booster gas such as pressurized air (10) to a motor (11), the motor (11) drives the gas pump (8), thereby increasing the pressure of the pressurized pilot gas flows, thereby branching the pressurized pilot gas into a first pilot gas flow (6) and a second pilot gas flow (7) having a pressure together that is sufficiently higher than the pressure required to close the back pressure valves (4, 5) of the hydrogen gas separation tank and the oxygen gas separation tank (1, 2).

4. The gas pressure balancing method according to claim 1 or 2, wherein the first pilot gas flow (6) is drawn from an oxygen tube (39), the second pilot gas flow (7) is drawn from a hydrogen tube (38), the two pilot gas flows are boosted by their respective generated gas booster pumps (47A, 47B), and the pumps (47A, 47B) are driven by motors (11) powered by a supply source of pressurized air (10).

5. The gas pressure balancing method according to claim 4, wherein the gas flow leaking from the bleed valve (13) of the feed-and-bleed valve system (12) is sent to each of its gas quality control measuring devices (15), and further, an adjustable auxiliary generating gas supply valve (42) is located in an auxiliary gas pipe (44) between each of the generating gas pipes (38, 39) and each of the gas quality control measuring devices (15), thereby the adjustable auxiliary generating gas supply valve (42) is induced by a signal drawn from a fluid flow measuring device (43) located between the bleed valve (13) and each of the gas receivers (46).

6. An electrolytic cell system having a pressure balancing valve system, The oxygen separation tank (1) and the hydrogen separation tank (2) are provided with pipe connections to each side of the separation diaphragm (17) in one or more electrolytic cell stacks (3). The oxygen back pressure valve (4) is coupled to the oxygen separation tank (1) and is configured to open for the controlled release of oxygen-generating gas at a predetermined oxygen-generating gas separation tank pressure. The hydrogen back pressure valve (5) is coupled to the hydrogen separation tank (2) and is configured to open for the controlled release of hydrogen-producing gas at a predetermined hydrogen-producing gas separation tank pressure. The back pressure valves (4, 5) are configured to open to release the generated gas to a predetermined, calibrated pilot gas pressure (6.1, 7.1), The feed-and-bleed valve system (12) generates a predefined, calibrated pilot gas pressure in the pilot gas within the pipe (48) that interconnects the feed valve (14) and the bleed valve (13). The bleed valve (13) is configured to deliver a bleed-off of pilot gas from the pipe (48), An electrolytic cell system in which the feed valve (14) is configured to adjust to deliver the desired predefined calibrated pressure (6.1, 7.1) of the pilot gas in the pipe (48).

7. The electrolytic cell system according to claim 6, wherein the first pilot gas flow (6) originates from an oxygen-producing gas pipe (39) and is connected to the feed-and-bleed valve system (12) via a product gas booster pump (47B) so that product gases for the first and second pilot gas flows (6, 7) are supplied to the feed-and-bleed valve arrangement (12), and the second pilot gas flow (7) originates from a hydrogen-producing gas pipe (38) and is connected to the feed-and-bleed valve system (12) via a further product gas booster pump (47A).

8. The electrolytic cell system according to claim 6, wherein the pilot gas supply source is connected to a gas pump (8) configured to act as a booster and further pressurize the pilot gas flow, and the pilot gas pump (8) is adapted to be driven by a motor (11) configured to receive its driving energy from a supply source of pressurized air (10).

9. The electrolytic cell system according to claim 7 or 8, wherein the back pressure valves (4, 5) are dome-loaded valves (22), the pilot pressure is supplied to the far side (16) of the dome membrane (23), and the near side (18) of the dome membrane (23) is fitted to contact two sets of orifices, namely, a first set of orifices (24) that are in fluid communication with the product separation tank described above, and a second set of orifices (25) that are in communication with the receivers for the respective product gases.

10. A gas quality control measuring device (15) is positioned in the gas outlet pipe (45) between the bleed valve (13) and the receiving container. The electrolytic cell system according to claim 7 or 9, wherein an auxiliary generating gas supply valve (42) is located in an auxiliary gas pipe (44) between each of the generating gas pipes (38, 39) and each of the gas quality control measuring devices (15), so that the auxiliary generating gas supply valve (42) is guided by a signal drawn from a fluid flow rate measuring device (43) located between the bleed valve (13) and each of the gas receivers (45).

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