Gas pressure regulator

Abstract

To suppress the occurrence of pressure fluctuation over a permitted range on a suction side of a compressor through easy control.SOLUTION: A gas pressure regulator includes: a gas line that is connected to a gas outlet of a gas generator; a compressor that is provided at the gas line; a reflux line that is connected to a suction side and an exhaust side of the compressor in the gas line so as to bypass the compressor; a suction side buffer tank that is provided on the suction side of the compressor in the gas line; a detection part that detects a pressure on the suction side of the compressor; a control valve that is provided at the reflux line; and a control part that controls the opening of the control valve based on a pressure on the suction side of the compressor, which has been detected by the detection part, in such a manner that the pressure on the suction side falls within a predetermined pressure range.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This specification discloses a gas pressure regulating device. [Background technology]

[0002] Conventionally, a compressor has been proposed that includes a compressor main body, a motor that drives the compressor main body, a discharge bypass flow path that connects a suction flow path through which fluid flows into the compressor main body with a discharge flow path through which fluid flows out of the compressor main body, and a discharge bypass valve provided in the discharge bypass flow path (see, for example, Patent Document 1). The compressor sets an MV value that maintains the pressure of the fluid in the discharge flow path at a constant value, and adjusts the closure degree of the discharge bypass valve to a closure degree corresponding to the MV value. The compressor also derives a target rotation speed so that the MV value becomes a predetermined value, and controls the motor to drive the compressor main body in accordance with the target rotation speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-067028 Summary of the Invention [Problem to be solved by the invention]

[0004] In a gas pressure regulating device that uses a compressor to regulate the pressure of gas generated by a gas generator, it is usually difficult to match the amount of gas generated by the gas generator with the amount of gas processed (discharge rate) by the compressor, which can cause large pressure fluctuations on the suction side of the compressor and lead to problems with the upstream gas generator. While it is conceivable to suppress the pressure fluctuations on the suction side by controlling the compressor discharge rate, this would require a response from the compressor manufacturer, resulting in increased costs.

[0005] The main object of the present disclosure is to suppress, through simple control, pressure fluctuations exceeding an allowable range on the suction side of a compressor in a gas pressure regulating device that regulates the pressure of gas generated by a gas generating device using a compressor. [Means for solving the problem]

[0006] The present disclosure has adopted the following means to achieve the above-mentioned main object.

[0007] The gas pressure regulating device of the present disclosure is a gas pressure regulating device that regulates the pressure of gas generated by a gas generating device, and comprises: a gas line connected to a gas outlet of the gas generating device; a compressor provided in the gas line; a reflux line connected to the suction side and discharge side of the compressor in the gas line so as to bypass the compressor; a suction side buffer tank provided in the gas line on the suction side of the compressor; a detection unit that detects the pressure on the suction side of the compressor; a control valve provided in the reflux line; and a control unit that controls the opening degree of the control valve based on the pressure on the suction side of the compressor detected by the detection unit so that the pressure on the suction side is within a predetermined pressure range.

[0008] The gas pressure regulating device disclosed herein includes a return line connected to the suction side and discharge side of the compressor so as to bypass the compressor, and a control valve provided in the return line. The control valve controls the opening of the control valve based on the pressure on the suction side of the compressor detected by the detector so that the pressure on the suction side remains within a predetermined pressure range. This allows for simple control to prevent pressure fluctuations on the suction side of the compressor from exceeding the allowable range. As a result, adverse effects on the upstream gas generator can be avoided. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a gas pressure regulating device according to an embodiment of the present invention; [Figure 2] 4 is a flowchart illustrating an example of a pressure regulation control process. [Figure 3] 10 is an explanatory diagram showing the time-dependent changes in suction side pressure Pin, opening degree A of the reflux valve, and control signal. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Next, embodiments of the present disclosure will be described with reference to the drawings.

[0011] FIG. 1 is a schematic diagram of a gas pressure regulator 20 according to this embodiment. The gas pressure regulator 20 regulates (boosts) the pressure of hydrogen gas generated by an electrolysis device 10 serving as a gas generator, and stores the hydrogen gas in a hydrogen tank 12. Here, the electrolysis device 10 is, for example, a solid oxide electrolysis device (SOEC), which includes a cathode (hydrogen electrode), an anode (oxygen electrode), and a solid electrolyte interposed between the cathode and the anode. The electrolysis device 10 is equipped with a solid oxide electrolysis cell that electrolyzes water vapor to generate hydrogen gas by supplying water vapor to the cathode and applying a power supply voltage between the cathode and the anode. The hydrogen gas generated at the cathode of the electrolysis cell is output to a hydrogen gas line L1 connected to the cathode outlet. The hydrogen gas then passes through the hydrogen gas line L1, has its pressure regulated (boosted) to a required pressure by the gas pressure regulator 20, and is then stored in the hydrogen tank 12.

[0012] 1, the gas pressure regulating device 20 includes a hydrogen gas line L1, a compressor 22, a suction-side buffer tank 24, a discharge-side buffer tank 26, a reflux line L2, a reflux valve 28, and a control device 40. The compressor 22 is installed on the hydrogen gas line L1. The compressor 22 has a processing capacity (discharge rate) higher than the supply rate per unit time of hydrogen supplied from the electrolysis device 10 to the hydrogen gas line L1. The suction-side buffer tank 24 is installed on the suction side of the compressor 22 on the hydrogen gas line L1, and the discharge-side buffer tank 26 is installed on the discharge side of the compressor 22 on the hydrogen gas line L1. In addition, a pressure sensor 32 is installed in the suction-side buffer tank 24 to detect the pressure inside the tank (suction-side pressure Pin).

[0013] The reflux line L2 returns a portion of the hydrogen gas discharged from the compressor 22 to the suction side. In this embodiment, the reflux line L2 is connected to the discharge side buffer tank 26 and to the hydrogen gas line L1 upstream of the suction side buffer tank 24 so as to bypass the compressor 22. The reflux valve 28 is a control valve installed on the reflux line L2 and controls the reflux amount of hydrogen gas by adjusting its opening degree A.

[0014] The control device 40 is configured as a microprocessor centered around a CPU 42, and in addition to the CPU 42, includes a ROM 44 for storing processing programs, a RAM 46 for temporarily storing data, and input / output ports (not shown). The suction-side pressure Pin from the pressure sensor 32 is input to the control device 40 via an input port. On the other hand, the control device 40 outputs control signals to the compressor 22, the reflux valve 28, and the like via an output port.

[0015] Next, a description will be given of the operation of the gas pressure regulator 20 configured as described above. Figure 2 is a flowchart showing an example of a pressure regulation control process executed by the CPU 42 of the control device 40. This process is repeatedly executed at predetermined time intervals (for example, every several hundred milliseconds to several seconds).

[0016] When the pressure regulation control process is executed, the CPU 42 of the control device 40 first drives the motor of the compressor 22 to operate the compressor 22 at rated pressure (step S100). Next, the CPU 42 inputs the suction-side pressure Pin from the pressure sensor 32 (step S110). The CPU 42 then determines whether the input suction-side pressure Pin is equal to or greater than a threshold value HH (step S120), equal to or greater than a threshold value H (step S130), equal to or less than a threshold value LL (step S140), or equal to or less than a threshold value L (step S150). Here, the threshold values ​​HH and H are threshold values ​​for determining whether the suction-side pressure Pin has approached the upper limit pressure of the pressure range (allowable pressure range) permitted in the electrolysis device 10, which is the upstream device of the gas pressure regulator 20. The threshold value HH is set to a pressure value lower than the upper limit pressure, and the threshold value H is set to a pressure value lower than the threshold value HH and higher than the target value Ptag. The values ​​LL and L are thresholds for determining whether the suction pressure Pin approaches the lower limit of the allowable pressure range. The threshold LL is set to a pressure value higher than the lower limit pressure, and the threshold L is set to a pressure value higher than the threshold LL and lower than the target value Ptag.

[0017] If the CPU 42 determines in step S120 that the suction-side pressure Pin is equal to or greater than the threshold HH, it sets an opening adjustment amount ΔA to decrease the opening A of the reflux valve 28 by a first rate (e.g., 10%) (step S160). If the CPU 42 determines in step S120 that the suction-side pressure Pin is not equal to or greater than the threshold HH and determines in step S130 that the suction-side pressure Pin is equal to or greater than the threshold H, it determines that the suction-side pressure Pin is equal to or greater than the threshold HH and is less than the threshold HH, and sets an opening adjustment amount ΔA to decrease the opening A of the reflux valve 28 by a second rate (e.g., 5%) that is less than the first rate (step S170). If the CPU 42 determines in step S140 that the suction-side pressure Pin is equal to or less than the threshold LL, it sets an opening adjustment amount ΔA to increase the opening A of the reflux valve 28 by a third rate (e.g., 10%) (step S180). If the CPU 42 determines in step S140 that the suction-side pressure Pin is not equal to or less than the threshold value LL and determines in step S150 that the suction-side pressure Pin is equal to or less than the threshold value L, it determines that the suction-side pressure Pin is greater than the threshold value LL and equal to or less than the threshold value L, and sets an opening adjustment amount ΔA to increase the opening A of the reflux valve 28 by a fourth rate (e.g., 5%) that is less than the third rate (step S190). If the CPU 42 determines in steps S120, S130, S140, and S150 that the suction-side pressure Pin is not equal to or greater than the threshold value HH, nor equal to or greater than the threshold value H, nor equal to or less than the threshold value LL, or equal to or less than the threshold value L, it determines that the suction-side pressure Pin is within an appropriate range that is greater than the threshold value L and less than the threshold value H, and sets the opening adjustment amount ΔA to 0 so as to maintain the current opening A of the reflux valve 28 (step S200).

[0018] After setting the opening adjustment amount ΔA of the recirculation valve 28 in this way, the CPU 42 outputs a control signal according to the set opening adjustment amount ΔA to the recirculation valve 28 (step S210), and ends the pressure regulation control process.

[0019] 3 is an explanatory diagram showing the suction-side pressure P in relation to the opening degree A of the reflux valve 28 and the change over time in the control signal to the reflux valve 28. In the gas pressure regulating device 20 of this embodiment, as shown in the figure, when the suction-side pressure P is equal to or greater than a threshold HH, the opening degree A of the reflux valve 28 is decreased by a first rate (10%) every predetermined time until the suction-side pressure P falls below the threshold HH. When the suction-side pressure P is equal to or greater than the threshold HH, the opening degree A of the reflux valve 28 is decreased by a second rate (5%) every predetermined time until the suction-side pressure P falls below the threshold H or reaches or exceeds the threshold HH. When the suction-side pressure P is equal to or greater than a threshold LL, the opening degree A of the reflux valve 28 is increased by a third rate (10%) every predetermined time until the suction-side pressure P exceeds the threshold LL. When the suction-side pressure P is greater than the threshold LL but less than the threshold L, the opening degree A of the reflux valve 28 is increased by a fourth rate (5%) every predetermined time until the suction-side pressure P exceeds the threshold L or falls below the threshold LL. In this way, the suction-side pressure Pin can be controlled within the allowable pressure range by simple control of simply comparing the suction-side pressure Pin with the threshold values ​​HH, H, LL, and L and increasing or decreasing the opening A of the reflux valve 28. As a result, it is possible to avoid a situation in which adverse effects are exerted on the electrolysis device 10, which is an upstream device.

[0020] Furthermore, since the compressor 22 is operated at a rated speed and is not used to control the suction side pressure Pin, there is no need to change the specifications of the compressor 22, which would require the compressor manufacturer to respond, and costs can be reduced.

[0021] Furthermore, since a suction-side buffer tank 24 is installed on the suction side of the compressor 22 in the hydrogen gas line L1, excessive pressure fluctuations in the suction-side pressure Pin can be suppressed, and the suction-side pressure Pin can be well controlled within the allowable pressure range by controlling the reflux valve 28. Furthermore, since a discharge-side buffer tank 26 is installed on the discharge side of the compressor 22 in the hydrogen gas line L1, pressure fluctuations on the discharge side of the compressor 22 can be suppressed, and the reflux amount of hydrogen gas refluxed by the reflux valve 28 can be stabilized.

[0022] It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present disclosure.

[0023] For example, in the above-described embodiment, the CPU 42 is configured to significantly increase the aperture A of the reflux valve 28 as the suction-side pressure Pin increases using two thresholds HH and H set on the higher pressure side of the target value Ptag. However, the CPU 42 may also be configured to significantly increase the aperture A of the reflux valve 28 as the suction-side pressure Pin increases using three or more thresholds set on the higher pressure side of the target value Ptag, or to use one threshold set on the higher pressure side of the target value Ptag and increase the aperture A of the reflux valve 28 by a predetermined percentage when the suction-side pressure Pin reaches or exceeds that threshold. Furthermore, the CPU 42 is configured to significantly decrease the aperture A of the reflux valve 28 as the suction-side pressure Pin decreases using two thresholds LL and L set on the lower pressure side of the target value Ptag. However, the CPU 42 may use three or more thresholds set on the low-pressure side of the target value Ptag to significantly reduce the opening degree A of the reflux valve 28 as the suction side pressure Pin decreases, or may use one threshold set on the low-pressure side of the target value Ptag to reduce the opening degree A of the reflux valve 28 by a predetermined percentage when the suction side pressure Pin falls below that threshold.

[0024] Furthermore, instead of controlling the reflux valve 28 using the threshold values ​​HH, H, LL, and L, the CPU 42 may control the reflux valve 28 by setting the target opening Atag of the reflux valve 28 using proportional (P) control, proportional-integral (PI) control, or proportional-integral-derivative (PID) control based on the deviation ΔP (=Pin-Ptag) between the suction-side pressure Pin and the target value Ptag so that the suction-side pressure Pin approaches the target value Ptag. The calculation formula for PID control is shown in the following formula (1). In formula (1), "kp" represents the proportional gain, "ki" represents the integral gain, and "kd" represents the differential gain.

[0025] Atag=kp(Ptag-Pin)+ki·∫(Ptag-Pin)dt+kd·d(Ptag-Pin) / dt …(1)

[0026] In the above-described embodiment, the gas pressure regulating device 20 includes the discharge-side buffer tank 26, but the discharge-side buffer tank 26 may be omitted.

[0027] In the above-described embodiment, the pressure sensor 32 is provided in the suction-side buffer tank 24, but it may also be provided in the hydrogen gas line L1 on the suction side of the compressor 22. [Industrial Applicability]

[0028] The present disclosure is applicable to the gas pressure regulating device manufacturing industry and the like. [Explanation of symbols]

[0029] 10 electrolysis device (gas generation device), 20 gas pressure regulator, 22 compressor, 24 suction side buffer tank, 26 discharge side buffer tank, 28 reflux valve (control valve), 32 pressure sensor (detection unit), L1 hydrogen gas line (gas line), L2 reflux line.

Claims

1. A gas pressure regulating device that regulates the pressure of gas generated by a gas generating device, a gas line connected to a gas outlet of the gas generator; a compressor provided in the gas line; a return line connected to the suction side and the discharge side of the compressor in the gas line so as to bypass the compressor; a suction-side buffer tank provided on the suction side of the compressor in the gas line; a detection unit that detects the pressure on the suction side of the compressor; a control valve provided in the reflux line; a control unit that controls an opening degree of the control valve based on the pressure on the suction side of the compressor detected by the detection unit so that the pressure on the suction side is within a predetermined pressure range; A gas pressure regulating device comprising:

2. 2. The gas pressure regulating device according to claim 1, the control unit controls the opening degree of the control valve based on the pressure on the suction side of the compressor detected by the detection unit while operating the compressor at a rated speed. Gas pressure regulator.

3. 3. The gas pressure regulating device according to claim 1 or 2, The control unit increases the opening of the control valve when the pressure on the suction side of the compressor detected by the detection unit is equal to or lower than a low-pressure side threshold that is higher than the lower-limit pressure of the predetermined pressure range, decreases the opening of the control valve when the pressure on the suction side of the compressor detected by the detection unit is lower than the upper-limit pressure of the predetermined pressure range and equal to or higher than a high-pressure side threshold that is higher than the low-pressure side threshold, and maintains the current opening of the control valve when the pressure on the suction side of the compressor detected by the detection unit is higher than the low-pressure side threshold and lower than the high-pressure side threshold. Gas pressure regulator.

4. 3. The gas pressure regulating device according to claim 1 or 2, a discharge-side buffer tank provided on the gas line on the discharge side of the compressor, the reflux line is connected to the upstream side of the suction-side buffer tank in the gas line and to the discharge-side buffer tank; Gas pressure regulator.

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