Gas pressure-based storage and discharge equipment, and gas pressure-based storage and discharge method

Abstract

The system allows for the appropriate storage and release of gas pressure outside of underground bedrock layers, and also supplies the stored pressure energy appropriately in accordance with energy demand. [Solution] The system includes a control device S that controls the distribution state of the first switching valve K1 and the opening state of the first on-off valve V1. The control device S performs a storage / discharge switching control that switches between a pressure storage / non-power generation control, which sets the first switching valve K1 to a bypass distribution state and the first on-off valve V1 to a first closed opening state, thereby accumulating pressure in the first bypass pipe H2 and keeping the expansion turbine ET in a non-rotating state, and a pressure release power generation control, which releases the gas pressure accumulated in the first bypass pipe H2 and keeps the expansion turbine ET in a rotating state.

Description

Technical Field

[0001] The present invention relates to a gas pressure utilization energy storage and discharge facility including a main gas pipe through which gas supplied from an upstream side can flow, and a first bypass pipe through which gas can flow in a form of bypassing the main gas pipe when an abnormality occurs in the main gas pipe, and a gas pressure utilization energy storage and discharge method.

Background Art

[0002] Conventionally, as shown in Patent Documents 1 and 2, a compressor is operated by electric power supplied from a renewable energy supply facility such as a solar panel or a power supply source such as a commercial power system, and the compressed air is stored in a pressure accumulation container. At the same time, as a technology for discharging electric power in a form of driving a generator by rotating an expansion turbine with compressed air when the compressed air is released from the pressure accumulation container, a compressed air energy storage technology (CAES) is known. Incidentally, in the compressed air energy storage technology (CAES) in Patent Document 1, the electric power generated by wind power generation is used for leveling.

[0003] The above-described compressed air energy storage technology (CAES) has an advantage of being easy to lengthen the power storage time compared to secondary batteries such as lithium ion batteries, and can relatively easily increase the power storage capacity, so it is a technology that can be effectively applied to large-scale power storage facilities.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Now, regarding the compressed air energy storage (CAES) technology mentioned above, most of the commercially available technologies currently use underground bedrock as the pressure storage vessel. As a result, they are not widely used in areas where underground bedrock does not exist or where underground bedrock cannot be utilized. Therefore, there was a need to develop a technology that could store gas at large capacity and high pressure, even in areas where underground bedrock layers do not exist or where underground bedrock layers cannot be utilized. Furthermore, there was a need for the development of technology that could appropriately supply the stored pressure energy in a manner that matched energy demand.

[0006] The present invention has been made in view of the above-mentioned problems, and its objective is to provide a gas pressure-utilizing storage and discharge equipment and a gas pressure-utilizing storage and discharge method that can appropriately store and release gas pressure outside of underground bedrock layers, and that can appropriately supply the stored pressure energy in accordance with energy demands. [Means for solving the problem]

[0007] To achieve the above objectives, a gas pressure-based storage and discharge system is provided. A gas pressure-based storage and discharge system comprising a main gas pipe through which gas supplied from the upstream side can flow, and a first bypass pipe through which gas can flow in a manner that bypasses the main gas pipe in the event of an abnormality in the main gas pipe, the characteristic configuration of which is: A first switching valve capable of switching the distribution state of gas supplied from the upstream side between a main distribution state, in which the gas is distributed to the main gas pipe, and a bypass distribution state, in which the gas is distributed to the first bypass pipe. At the inlet of the downstream connection between the first bypass piping and the main gas piping, a first on-off valve is provided that can switch the opening state of the first bypass piping between a first closed opening state, which includes a fully closed state, and a first open opening state, which includes a fully open state. An expansion turbine that causes the pressurized gas stored in the first bypass pipe to flow through and expand, and a generator that generates electricity using the shaft output of the expansion turbine, The system includes a control device that controls the distribution state of the first switching valve and the opening state of the first on / off valve, The control device performs a storage / discharge switching control that switches between a pressure storage / discharge switching control, which sets the first switching valve to the bypass distribution state and the first on / off valve to the first closed opening state, thereby accumulating pressure in the first bypass piping and keeping the expansion turbine in a non-rotating state, and a pressure release power generation control, which releases the gas pressure accumulated in the first bypass piping and keeps the expansion turbine in a rotating state.

[0008] A gas pressure-based storage and discharge method to achieve the above objective is: The system includes a main gas pipe through which gas supplied from the upstream side can pass, and a first bypass pipe through which gas can pass in a manner that bypasses the main gas pipe in the event of an abnormality in the main gas pipe. A first switching valve capable of switching the distribution state of gas supplied from the upstream side between a main distribution state, in which the gas is distributed to the main gas pipe, and a bypass distribution state, in which the gas is distributed to the first bypass pipe. At the inlet of the downstream connection between the first bypass piping and the main gas piping, a first on-off valve is provided that can switch the opening state of the first bypass piping between a first closed opening state, which includes a fully closed state, and a first open opening state, which includes a fully open state. A gas pressure-based storage and discharge method in a gas pressure-based storage and discharge facility comprising an expansion turbine that expands the pressurized gas stored in the first bypass pipe, and a generator that generates electricity using the shaft output of the expansion turbine, wherein the characteristic configuration is: The key feature is the execution of a storage / discharge switching control that switches between a storage / discharge switching control, which sets the first switching valve to the bypass distribution state and the first on / off valve to the first closed opening state, thereby accumulating pressure in the first bypass piping and putting the expansion turbine into a non-power generation state, and a storage / discharge switching control, which releases the gas pressure accumulated in the first bypass piping and puts the expansion turbine into a power generation state.

[0009] According to the above-described configuration, the first bypass pipe, which is not used in normal conditions when there is no abnormality in the main gas piping, and which has a relatively large capacity and high pressure resistance, can be used as a pressure accumulator. Therefore, compressed gas energy storage (CAES) can be realized without incurring the cost of installing a new pressure accumulator. Furthermore, according to the above technology, the pressure energy of the gas, which was previously wasted, can be stored and released as needed. During storage, high-pressure gas (for example, relatively high-pressure primary gas supplied from a gas supply facility) is stored, and during release, high-pressure gas can be supplied to an expansion turbine and discharged. This makes it possible to realize a gas pressure-utilizing storage and discharge equipment and a gas pressure-utilizing storage and discharge control method that not only converts the pressure energy of the gas into electrical energy and supplies it, but also enables the supply of electrical energy in accordance with the electricity demand. Furthermore, the statement that it is possible to supply electrical energy in accordance with electricity demand means that electricity can be supplied in a form where the time of pressure accumulation (storage) and the time of pressure release (discharge) are different. This means that the technical concept is significantly different from the conventional method of generating electricity by simply installing an expansion turbine and generator in gas piping. This enables the realization of a gas pressure-based storage and discharge facility and a gas pressure-based storage and discharge method that can appropriately store and release gas pressure outside of underground bedrock layers, and appropriately supply the stored pressure energy in accordance with energy demand.

[0010] Further characteristic features of the gas pressure-based storage and discharge equipment are: A compressor is provided downstream of the first switching valve in the first bypass piping and upstream of the expansion turbine to increase the pressure of the gas led to the first bypass piping. The control device, when switched to the non-power generation accumulator control, executes a pressure boost control to increase the gas pressure in the first bypass pipe if the pressure upstream of the upstream connection between the main gas pipe and the first bypass pipe falls below a first pressure boost reference threshold which is less than the design allowable pressure of the first bypass pipe.

[0011] The first bypass piping, which serves as a pressure accumulator, is supplied with gas adjusted to a predetermined pressure from the gas supply equipment. However, depending on the gas usage upstream, the primary pressure at the inlet of the first bypass piping may be relatively low. According to the above characteristic configuration, when the control device is switched to non-power generation control for pressure accumulation, if the pressure upstream of the upstream connection point between the main gas piping and the first bypass piping falls below the first pressure boosting threshold, which is less than the design allowable pressure of the first bypass piping, the compressor is driven to perform pressure boosting control to increase the pressure of the gas in the first bypass piping. Therefore, when the gas pressure at the inlet of the first bypass piping is relatively low (below the first pressure boosting threshold), the gas introduced into the first bypass piping is boosted by the compressor, thereby maintaining the pressure of the gas accumulated in the first bypass piping at a relatively high level. This allows for a further improvement in the pressure accumulation capacity compared to when the gas on the upstream side (primary side) is accumulated in the first bypass piping without being boosted. Incidentally, in actual operation, the control device will control the compressor's operation so that the gas pressure in the first bypass pipe is below the design allowable pressure of the first bypass pipe. Furthermore, while the compressor is preferably located at the outlet of the first switching valve to ensure sufficient pressure accumulation capacity, it can be installed anywhere on the downstream side of the first switching valve in the first bypass piping and upstream side of the expansion turbine.

[0012] Further characteristic features of the gas pressure-based storage and discharge equipment are: The expansion turbine is provided between the outlet of the first on / off valve of the first bypass piping and the downstream connection portion. The control device, in the pressure discharge power generation control, sets the first on-off valve to a first open state to discharge the gas pressure accumulated in the first bypass piping and put the expansion turbine into a power generation state.

[0013] According to the above-described configuration, there is no need to install any new piping other than the conventionally provided main gas piping and first bypass piping. Therefore, pressure discharge power generation control can be achieved with a relatively simple configuration that does not require any additional components.

[0014] A further characteristic configuration of the gas pressure utilization energy storage and discharge equipment is A compressor for boosting the gas introduced into the first bypass pipe is provided on the upstream side of the expansion turbine and downstream of the first switching valve of the first bypass pipe. A connecting pipe for connecting the outlet of the compressor of the first bypass pipe and the main gas pipe is provided. The expansion turbine is provided in the connecting pipe. The connecting pipe is provided with a second on-off valve capable of switching the opening state between a second closing opening state including a fully closed state and an opening side opening state including a fully open state. In the charge-discharge switching control, the control device performs the pressure accumulation non-power generation control in which the first switching valve is in the bypass distribution state, the first on-off valve is in the first closing opening state, and the second on-off valve is in the second closing opening state to accumulate gas pressure in the first bypass pipe and set the expansion turbine in a non-power generation state, and the pressure release power generation control in which the second on-off valve is in the second opening opening state to release the gas pressure accumulated in the first bypass pipe and set the expansion turbine in a power generation state, and switches between them.

[0015] With the above characteristic configuration, by providing a connecting pipe connecting the outlet of the compressor of the first bypass pipe and the main gas pipe and providing the expansion turbine in the connecting pipe, even when the laying length of the first bypass pipe is relatively long and the energy storage capacity is large, the input position for inputting power to the compressor for energy storage and the output position for outputting power from the expansion turbine and the generator driven by its shaft output due to pressure release can be brought closer, improving the usability as an energy storage and discharge equipment.

[0016] A further characteristic configuration of the gas pressure utilization energy storage and discharge equipment is A compressor for boosting the gas introduced into the first bypass pipe is provided on the upstream side of the expansion turbine and downstream of the first switching valve of the first bypass pipe. The first bypass pipe is provided with a second bypass pipe that bypasses the compressor, and a first flow state that guides gas to the compressor and does not allow gas to flow through the second bypass pipe, and a second flow state that does not guide gas to the compressor and allows gas to flow through the second bypass pipe, and a second switching valve that can be switched between them. The control device is configured to be able to execute a determination process for determining whether or not the main gas pipe on the downstream side of the upstream connection portion between the main gas pipe and the first bypass pipe is in an abnormal state. When the control device determines in the determination process that the main gas pipe is in the abnormal state, in both the accumulator non-power generation control and the pressure release power generation control, the first switching valve is switched to the bypass distribution state, the second switching valve is switched to the second flow state, and the first on-off valve is switched to the first open degree state.

[0017] According to the above characteristic configuration, for example, when an abnormality such as gas leakage occurs in the main gas pipe due to an earthquake or the like, the control device switches the first switching valve to the bypass distribution state, the second switching valve to the second flow state, and the first on-off valve to the first open degree state in both the accumulator non-power generation control and the pressure release power generation control. Therefore, stable gas supply can be continued to the gas consumers on the downstream side of the main gas pipe in a state where gas flows through the second bypass pipe without passing through the main gas pipe.

[0018] A further characteristic configuration of the gas pressure utilization energy storage and power generation facility is An equalizing device for equalizing the secondary side pressure of the main gas pipe to a set pressure is provided on the downstream side of the downstream connection portion in the main gas pipe. The control device is to execute the accumulator non-power generation control and the pressure release power generation control so as to maintain the primary side pressure of the equalizing device at or above the set pressure.

[0019] As explained above, when accumulating gas from the upstream side in the first bypass piping (non-power generation control) and releasing gas to rotate the expansion turbine (power generation control) are performed, the pressure on the upstream side (primary side) of the pressure regulating device may fall below the set pressure that should be set on the downstream side (secondary side). In this case, there is a risk that the supply pressure of gas supplied to the downstream (secondary side) consumers will be insufficient, and the appropriate gas supply may not be maintained. According to the above characteristic configuration, the control device performs accumulating non-power generation control and releasing power generation control to maintain the primary side pressure of the pressure regulating device at or above the set pressure. Therefore, while achieving storage and discharge by appropriately switching between the state in which accumulating non-power generation control and releasing power generation control are performed and the state in which they are stopped, a stable supply of gas to downstream (secondary) consumers can be appropriately achieved. For example, during late-night hours when gas usage downstream of the pressure regulating device is relatively low, the system actively implements accumulating pressure non-generation control and discharge pressure generation control. Conversely, during daytime hours when gas usage downstream of the pressure regulating device is relatively high, the system suppresses (stops) accumulating pressure non-generation control and discharge pressure generation control, thereby achieving both power transfer and a stable gas supply to the secondary side. Furthermore, even during periods when gas usage on the downstream (secondary) side is low, if the secondary pressure of the pressure regulating device is lower than the set pressure, the control device will stop the accumulator non-power generation control and the discharge power generation control, and will also execute control to increase the secondary pressure by allowing gas to flow through the main gas piping.

[0020] Further characteristic features of the gas pressure-based storage and discharge equipment are: The power load supplied with power from the generator is configured to also be able to receive power from the power grid in the area where the first bypass piping is laid. The control device is configured to receive whether the power demand in the power grid in the area where the first bypass piping is laid is below a predetermined lower limit threshold for power demand. The control device, upon receiving notification that the power demand in the power grid is below the lower limit threshold for power demand, at least stops the non-generation control of the accumulating pressure and supplies power from the power grid to the power load.

[0021] According to the above-described configuration, when the demand for power in the area where the first bypass piping is laid decreases significantly, and the supply of renewable energy to the power grid far exceeds the demand, the non-generation control of the accumulating pressure is stopped, and the power generated by the non-generation control of the accumulating pressure is used to prioritize the consumption of power from the power grid by the power load that is normally supplied, thereby effectively suppressing the strain on the power grid. [Brief explanation of the drawing]

[0022] [Figure 1] This diagram shows the gas flow state when the gas pressure-based storage and discharge equipment according to the first embodiment is in a normal gas supply state. [Figure 2] This figure shows the gas flow state when the gas pressure-based storage and discharge equipment according to the first embodiment is performing storage and non-power generation control. [Figure 3] This figure shows the gas flow state when the gas pressure-based storage and discharge equipment according to the first embodiment is performing pressure-releasing power generation control. [Figure 4] This diagram shows the gas flow state when the main gas piping is determined to be in an abnormal state in the gas pressure-based storage and discharge equipment according to the first embodiment. [Figure 5] This figure shows the gas flow state when the gas pressure-based storage and discharge equipment according to the second embodiment is in a non-power generation state. [Figure 6] This figure shows the gas flow state when the gas pressure-based storage and discharge equipment according to the second embodiment is in a pressure-releasing power generation state. [Modes for carrying out the invention]

[0023] The gas pressure-based storage and discharge equipment 100 and gas pressure-based storage and discharge method according to embodiments of the present invention are capable of appropriately storing and releasing gas pressure outside of underground bedrock layers, and of appropriately supplying the stored pressure energy in accordance with energy demand. Hereinafter, embodiments of the gas pressure-based storage and discharge equipment 100 and the gas pressure-based storage and discharge method according to the embodiment will be described based on Figures 1 to 6.

[0024] [First Embodiment] As shown in Figure 1, the gas pressure-utilizing storage and discharge equipment 100 according to the first embodiment includes a main gas pipe H1 through which gas (for example, city gas 13A) supplied from an upstream side such as a gas supply equipment (not shown) can pass, and a first bypass pipe H2 through which gas can pass in a manner that bypasses the main gas pipe H1 in the event of an abnormality in the main gas pipe H1. Furthermore, the gas pressure-utilizing storage and discharge equipment 100 includes a first switching valve K1 that can switch the distribution state between a main distribution state (distribution state shown in Figure 1) in which the gas supplied from the upstream side is distributed to the main gas pipe H1 and a bypass distribution state (distribution state shown in Figures 2, 3, and 4) in which the gas is distributed to the first bypass pipe H2, and a first closing valve at the inlet of the downstream connection part G2 between the first bypass pipe H2 and the main gas pipe H1 that opens the first bypass pipe H2 to a closed state including a fully closed state. The system includes a first on-off valve V1 that can switch between an open state and a first open state which includes an open state and a fully open state; an expansion turbine ET that causes pressurized gas to flow through and expand in a first bypass pipe H2; a generator E that generates electricity using the shaft output of the expansion turbine ET; a compressor C located downstream of the first switching valve K1 in the first bypass pipe H2 and upstream of the expansion turbine ET that pressurizes the gas led to the first bypass pipe H2; and a control device S that controls the distribution state of the first switching valve K1, the opening state of the first on-off valve V1, and the drive state of the compressor C.

[0025] The control device S is constructed from hardware including a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory), as well as software implemented therein. The control device S may be installed near the first bypass pipe H2 where the gas is stored and directly connected to various devices by wire or wireless connection, or it may be installed at a location away from the first bypass pipe H2 and configured to be electrically able to communicate with the aforementioned devices via a network line N such as the Internet.

[0026] In this first embodiment, the main gas piping H1 is provided with a pressure regulating device RV downstream of the downstream connection G2 described above, which regulates the secondary pressure of the main gas piping H1 to a set pressure. The pressure regulating device RV can suitably utilize a commonly known pilot governor type pressure regulating device.

[0027] Furthermore, a second pressure gauge P2 for measuring gas pressure is provided at the inlet of the upstream connection section G1, which is the upstream connection point between the main gas pipe H1 and the first bypass pipe H2, where the first switching valve K1 is installed. In addition, a first pressure gauge P1 for measuring gas pressure is provided downstream of the downstream connection section G2 and upstream of the pressure regulating device RV. The control device S is configured to receive the pressure measured by the first pressure gauge P1 and the second pressure gauge P2 via wired or wireless connection. Incidentally, the gas piping such as the main gas piping H1 and the first bypass piping H2 described herein is made of steel, and for example, those designed to have a design allowable pressure of about 7.0 MPa are preferably used. Incidentally, gas at a primary pressure (for example, a pressure of about 2 MPa to 4 MPa) below the above design allowable pressure (for example, a pressure of about 7 MPa or less) usually flows through the main gas piping H1 and the first bypass piping H2.

[0028] The compressor C is located downstream of the first switching valve K1 in the first bypass piping H2 and upstream of the expansion turbine ET, and is configured to be rotationally driven by a motor M powered by a commercial power grid (not shown). The control device S controls the drive of the motor M, and can raise the pressure of the gas after compression by the compressor C to, for example, the design allowable pressure of the first bypass piping H2. From the viewpoint of improving the amount of accumulated pressure, which will be described later, it is preferable to install the compressor C at the outlet of the first switching valve K1 in the first bypass piping H2. In this specification, the outlet of a device means the vicinity of the connection point between the device and the piping downstream of it, and the inlet of a device means the vicinity of the connection point between the device and the piping upstream of it.

[0029] The expansion turbine ET is installed between the first on-off valve V1 and the downstream connection G2 of the first bypass piping H2. Although cold heat is generated when the gas is expanded in the expansion turbine ET, the expansion turbine ET according to the first embodiment employs a shaft levitation type in which the rotating shaft is levitated by magnetic force, so that it can be used for gas expansion even when the temperature drops to, for example, several tens of degrees Celsius. Incidentally, a cold energy recovery heat exchanger EX1 is provided at the outlet of the expansion turbine ET, which is capable of recovering the cold energy contained in the gas expanded by the expansion turbine ET.

[0030] The generator E, which is rotationally driven by the shaft output of the expansion turbine ET, is configured to include an inverter that can adjust the generated power to a desired frequency and voltage. The power generated by the generator E can be supplied via the first power line D1 to a computer CS, such as a supercomputer capable of performing predetermined calculations (an example of a power load that generates heat by using the supplied power). Here, the computer CS is also supplied with power from the commercial power grid via the second power line D2. Furthermore, the electricity generated by generator E can be suitably used not only for supplying to computer CS, but also for charging commercial EVs, etc.

[0031] Now, the computer system CS, which consists of the supercomputers mentioned above, generates heat as it performs many calculations. Therefore, in this first embodiment, the cooling energy of the gas recovered by the cooling energy recovery heat exchanger EX1 is guided to a cooler EX2 provided on the computer CS, which is a power load, and the heating energy of the computer CS is guided to the cooling energy recovery heat exchanger EX1, and a heat medium circulation path H5 is provided, and the heat medium is circulated in the heat medium circulation path H5 by a pump (not shown). This makes it possible to appropriately process the cooling energy generated by the expansion of the gas by the expansion turbine ET without incurring additional costs.

[0032] Now, in the gas pressure utilization storage and discharge equipment 100 according to this embodiment, the gas pressure can be appropriately stored and released outside of underground bedrock layers, and the following control is performed in order to appropriately supply the stored pressure energy in accordance with the energy demand. Specifically, the control device S performs a storage / discharge switching control that switches between a pressure storage / discharge switching control, which sets the first switching valve K1 to a bypass distribution state and the first on / off valve V1 to a first closed open state, thereby accumulating pressure in the first bypass pipe H2 and keeping the expansion turbine ET in a non-rotating state, and a pressure release / discharge power generation control, which releases the gas pressure accumulated in the first bypass pipe H2 and keeps the expansion turbine ET in a rotating state.

[0033] Furthermore, while the first closed-open state basically means the fully closed state, from the perspective of maintaining rotation at the lowest rotational speed without stopping the rotation of the expansion turbine ET even in the first closed-open state, it also includes maintaining a predetermined closed-side opening (for example, an opening of a few percent). The first open position basically means the fully open position, but from the perspective of the processing capacity of the expansion turbine ET, it also includes maintaining an open position that is closer to the closed position than the fully open position. Here, it is preferable that the accumulator non-power generation control and the release pressure power generation control be performed, for example, during nighttime hours when the amount of gas used on the secondary side of the pressure regulating device RV is relatively low.

[0034] When the control device S performs non-power generation control for pressure accumulation, for example, the gas flow state shown in Figure 2 is achieved, and the gas pressurized by the compressor C is pumped between the compressor C and the first on-off valve V1 in the first bypass piping H2, thereby accumulating pressure. In other words, the piping between the compressor C and the first on-off valve V1 in the first bypass piping H2 functions as a pressure accumulation piping H2a (piping within the range of L1 in the drawing) where pressure is accumulated. On the other hand, when the control device S performs pressure release power generation control, for example, the gas flow state shown in Figure 3 is reached, and the gas stored in the pressure accumulator pipe H2a is released in a manner in which it expands via the expansion turbine ET, and electricity is generated by the generator E. In this first embodiment, since the expansion turbine ET is located at the outlet of the first on-off valve V1 of the first bypass piping H2, in the pressure release power generation control, the control device S sets the first on-off valve V1 to a first open state to release the gas pressure accumulated in the first bypass piping H2 and put the expansion turbine ET into a power generation state.

[0035] Incidentally, in the gas flow state shown in Figure 3, gas is guided to compressor C and compressor C is driven, and gas is stored in the accumulating pipe H2a. However, in the discharge power generation control, compressor C does not need to be driven. Furthermore, in the discharge power generation control, when an abnormality is detected in the main gas pipe H1, the pressure in the accumulating pipe H2a is controlled to reach the lower limit pressure value for discharge power generation (for example, a pressure of 3.0 MPa or higher) in order to quickly supply gas to the downstream side (secondary side) using the first bypass pipe H2. With the above control, the first bypass pipe H2 (pressure accumulating pipe H2a) will function as a battery, and it is assumed that it can achieve a storage capacity of 10 MWh or more, for example, based on the capacity of the first bypass pipe H2 currently in operation in Japan. The gas pressure-based storage and discharge equipment 100 also functions well as a backup battery during disasters.

[0036] Now, when the control device S is switched to accumulator non-power generation control, it can operate the compressor C and control it so that it is driven only when the pressure on its primary side (the pressure upstream of the upstream connection G1 between the main gas pipe H1 and the first bypass pipe H2) falls below a predetermined pressure. For example, when the control device S is switched to non-power generation control for accumulating gas, if the pressure upstream of the upstream connection G1 between the main gas pipe H1 and the first bypass pipe H2 falls below the first pressure boosting threshold (for example, a pressure of about 1 MPa to 4 MPa) which is less than the above-mentioned design allowable pressure of the first bypass pipe H2, the control device S drives the compressor C to boost the gas in the first bypass pipe H2 and performs pressure boosting control. This allows for energy storage when the primary pressure is relatively low, by boosting it to a pressure suitable for storage above the first boost threshold and storing it in the first bypass pipe H2 (storage pipe H2a). On the other hand, when the primary pressure is high, above the first boost threshold, the gas at the primary pressure is stored directly in the first bypass pipe H2 (storage pipe H2a) without driving the compressor C, thus achieving energy-efficient storage that does not require external power supply.

[0037] Furthermore, the gas pressure-utilizing storage and discharge equipment 100 according to the first embodiment is equipped with a pressure regulating device RV to maintain the secondary pressure at a set pressure. However, the pressure regulating device RV cannot control the secondary pressure to the desired pressure (set pressure) unless the secondary pressure is equal to or greater than the set pressure. Therefore, the control device S performs accumulator non-power generation control and discharge power generation control so that the pressure regulating device RV maintains the primary side pressure at or above the set pressure. To elaborate, when the control device S is performing non-power generation control for accumulating pressure, in other words, when the first switching valve K1 is in the bypass distribution state and the first on-off valve V1 is in the first closed-open state, and gas is not supplied to the upstream side (primary side) of the pressure regulating device RV, and the pressure measured by the first pressure gauge P1 is less than the set pressure, the control device S performs either a first switching control to switch the first switching valve K1 from the bypass distribution state to the main distribution state, or a second switching control to switch the first on-off valve V1 from the first closed-open state to the first open-open state. In this case, the control device S may perform both the first and second switching controls.

[0038] Furthermore, in the gas pressure-utilizing storage and discharge equipment 100 according to the first embodiment, as described above, the computer CS (an example of a power load) to which power is supplied from the generator E is configured to also be able to receive power from the power grid (not shown) in the area where the first bypass pipe H2 is laid. However, in the gas pressure-utilizing storage and discharge equipment 100, the following control is performed in order to prevent the power grid from becoming congested when the supply from the power grid exceeds the demand. In other words, the control device S is configured to receive whether the power demand in the power grid in the area where the first bypass pipe H2 is laid is below a predetermined lower limit threshold for power demand. When the control device S receives that the power demand in the power grid is below the lower limit threshold for power demand, it stops the pressure relief power generation control and supplies power from the power grid to the computer CS. Thus, the gas pressure-based storage and discharge equipment 100 according to the first embodiment functions well as a storage and discharge equipment that can flexibly respond to power grid congestion.

[0039] Now, the first bypass pipe H2 is provided to ensure a smooth supply of gas to the downstream (secondary) side even if damage or other abnormalities occur in the main gas pipe H1. In order to perform this function, the gas pressure utilization storage and discharge equipment 100 according to the first embodiment may be configured as follows. That is, as shown in Figure 4, the first bypass piping H2 may be equipped with a second bypass piping H3 that bypasses the compressor C, and a second switching valve K2 that can switch between a first flow state (not shown) in which gas is guided to the compressor C but gas is not allowed to flow through the second bypass piping H3, and a second flow state (shown in Figure 4) in which gas is allowed to flow through the second bypass piping H3 without guiding gas to the compressor C. The control device S is configured to perform a determination process that can determine whether the main gas piping H1 downstream of the upstream connection G1 is in an abnormal state. If the determination process determines that the main gas piping H1 is in an abnormal state, the control device S will perform the following controls in both the accumulator non-power generation control and the discharge power generation control: switch the first switching valve K1 to the bypass distribution state, switch the second switching valve K2 to the second flow state, and switch the first on / off valve V1 to the first open state. This allows for the continued and reliable supply of gas to downstream (secondary) consumers by diverting gas through the first bypass pipe H2, even if an abnormality occurs in the main gas pipeline H1.

[0040] Furthermore, in the above determination process, the control device S determines that the main gas piping H1 is in an abnormal state if, for example, the pressure of the first pressure gauge P1 decreases over time while the pressure regulating device RV is seismically shut off.

[0041] [Second Embodiment] The gas pressure-based energy storage and discharge equipment 100 according to the second embodiment differs from the gas pressure-based energy storage and discharge equipment 100 according to the first embodiment in that the installation locations of the expansion turbine ET, the generator E, and a series of related components are different. The gas pressure-based storage and discharge equipment 100 according to the second embodiment will be described below with reference to Figures 5 and 6. In the following description, only the characteristic configuration of the gas pressure-based storage and discharge equipment 100 according to the second embodiment will be described, and the same configuration as in the first embodiment will not be described.

[0042] In the gas pressure-utilizing storage and discharge equipment 100 according to the second embodiment, as shown in Figures 5 and 6, a connecting pipe H4 is provided that connects the outlet of the compressor C of the first bypass pipe H2 to the main gas pipe H1. The connecting pipe H4 is provided such that the fourth connection point G4, which is the connection point with the main gas pipe H1, is located between the first switching valve K1 and the pressure regulating device RV. Furthermore, the expansion turbine ET and the cold energy recovery heat exchanger EX1 are installed between the third connection point G3 and the fourth connection point G4, which are the connection points between the connecting pipe H4 and the first bypass pipe H2, in the order described above, starting from the upstream side. Furthermore, a second on-off valve V2 is provided between the third connection point G3 of the connecting pipe H4 and the expansion turbine ET, which can switch the opening state of the connecting pipe H4 between a second closed opening state, which includes a fully closed state, and a second open opening state, which includes a fully open state. The control device S performs a control that switches between two modes in the storage and discharge switching control: storage and discharge switching control, which involves setting the first switching valve K1 to the bypass distribution state, the first on-off valve V1 to the first closed open state, and the second on-off valve V2 to the second closed open state to store gas pressure in the first bypass pipe H2 and put the expansion turbine ET into a non-power generation state (control in the state shown in Figure 5); and discharge power generation switching control, which involves setting the second on-off valve V2 to the second open state to release the gas pressure stored in the first bypass pipe H2 and put the expansion turbine ET into a power generation state (control in the state shown in Figure 6).

[0043] [Another embodiment] (1) In the above embodiment, a compressor C for pressurizing the gas supplied to the first bypass pipe H2 is provided on the upstream side of the first bypass pipe H2, but the compressor C does not necessarily have to be provided. In this case, the primary pressure gas is directly guided to the first bypass pipe H2 from the upstream side of the main gas pipe H1, thereby accumulating pressure in the first bypass pipe H2. In addition, when accumulating pressure in the first bypass pipe H2, the control device S may be configured to pre-increase the gas pressure supplied to the main gas pipe H1 in the gas supply equipment (not shown) that supplies gas upstream of the main gas pipe H1. Incidentally, in the configuration according to the other embodiment (1), it is possible to achieve this without pre-increasing the pressure on the upstream side of the main gas piping H1 (the primary side of the first switching valve K1).

[0044] (2) In the above embodiment, the first switching valve K1 is exemplified as being composed of one three-way switching valve. The first switching valve K1 may be composed of, for example, an on-off valve for opening and closing the main gas pipe H1 and an on-off valve for opening and closing the first bypass pipe H2. The same applies to the second switching valve K2; it may be composed of two switching valves instead of a single three-way switching valve.

[0045] (3) The equipment for energy storage consisting of a compressor C and a drive motor M, and the equipment for discharge consisting of an expansion turbine ET and a generator E, may each be configured to consist of multiple units.

[0046] (4) In the above embodiment, the first pressure gauge P1 and the second pressure gauge P2 do not necessarily have to be provided. In this case, the control device S does not perform control based on the pressure measured by the first pressure gauge P1 and the second pressure gauge P2.

[0047] (5) In the above embodiment, the pressure regulating device RV is not necessarily required in the gas pressure utilization storage and discharge equipment 100.

[0048] (6) In the above embodiment, a configuration may be adopted in which a heating device for heating gas is provided at the inlet of the expansion turbine ET. In this configuration, if the temperature of the gas input to the expansion turbine ET can be raised to a sufficiently high temperature, it is not necessary to use a shaft-levitation type expansion turbine ET.

[0049] (7) In the above embodiment, the computer CS as a power load does not necessarily have to be provided.

[0050] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, provided that no inconsistencies arise. Moreover, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the object of the present invention. [Industrial applicability]

[0051] The gas pressure-based energy storage and discharge equipment and gas pressure-based energy storage and discharge method can be effectively utilized as a device that can appropriately store and release gas pressure outside of underground bedrock layers, and can appropriately supply the stored pressure energy in accordance with energy demand. [Explanation of Symbols]

[0052] 100: Gas pressure-based storage and discharge equipment C: Compressor CS: Calculator (power load) E: Generator ET: Expansion Turbine EX1:Cold heat recovery heat exchanger G1: Upstream connection G2: Downstream connection G3: Third connection point G4: Fourth connection point H1: Main gas piping H2: First bypass piping H2a: Pressure accumulating piping H3: Second bypass piping H4: Connection piping H5: Heat medium circulation path K1: First switching valve K2: Second switching valve RV:Pressure regulator S: Control device V1: First on / off valve V2: Second on / off valve

Claims

1. A gas pressure-based storage and discharge system comprising a main gas pipe through which gas supplied from the upstream side can flow, and a first bypass pipe through which gas can flow in a manner that bypasses the main gas pipe in the event of an abnormality in the main gas pipe, A first switching valve capable of switching the distribution state of gas supplied from the upstream side between a main distribution state, in which the gas is distributed to the main gas pipe, and a bypass distribution state, in which the gas is distributed to the first bypass pipe. At the inlet of the downstream connection between the first bypass piping and the main gas piping, a first on-off valve is provided that can switch the opening state of the first bypass piping between a first closed opening state, which includes a fully closed state, and a first open opening state, which includes a fully open state. An expansion turbine that causes the pressurized gas to flow through the first bypass pipe and expand, and a generator that generates electricity using the shaft output of the expansion turbine, The system includes a control device that controls the distribution state of the first switching valve and the opening state of the first on / off valve, The control device performs a gas pressure-utilizing storage and discharge equipment that switches between a pressure accumulation non-power generation control, which sets the first switching valve to the bypass distribution state and the first on-off valve to the first closed-open state, thereby accumulating pressure in the first bypass piping and keeping the expansion turbine in a non-rotating state, and a pressure release power generation control, which releases the gas pressure accumulated in the first bypass piping and keeps the expansion turbine in a rotating state.

2. A compressor is provided downstream of the first switching valve in the first bypass piping and upstream of the expansion turbine to increase the pressure of the gas led to the first bypass piping. The gas pressure utilization storage and discharge equipment according to claim 1, wherein when the control device is switched to the pressure storage non-power generation control, if the pressure upstream of the upstream connection between the main gas piping and the first bypass piping falls below a first pressure boosting reference threshold which is less than the design allowable pressure of the first bypass piping, the compressor is driven to perform a pressure boosting control to increase the gas pressure in the first bypass piping.

3. The expansion turbine is provided between the outlet of the first on / off valve of the first bypass piping and the downstream connection portion. The gas pressure utilization storage and discharge equipment according to claim 1 or 2, wherein the control device, in the pressure discharge power generation control, sets the first on-off valve to a first open state to discharge the gas pressure stored in the first bypass piping and puts the expansion turbine into a power generation state.

4. A compressor is provided downstream of the first switching valve in the first bypass piping and upstream of the expansion turbine to increase the pressure of the gas led to the first bypass piping. The first bypass piping includes a connecting pipe that connects the compressor outlet to the main gas piping, The expansion turbine is provided in the connecting pipe, The aforementioned connecting pipe is equipped with a second on-off valve that can switch between a second closed-off state, which includes a fully closed state, and a second open-off state, which includes a fully open state. The gas pressure utilization storage and discharge equipment according to claim 1 or 2, wherein the control device switches between, in the storage and discharge switching control, the first switching valve is set to the bypass distribution state, the first on-off valve is set to the first closed open state, and the second on-off valve is set to the second closed open state to store gas pressure in the first bypass piping and put the expansion turbine into a non-power generation state, and the second on-off valve is set to the second open state to release the gas pressure stored in the first bypass piping and put the expansion turbine into a power generation state.

5. A compressor is provided downstream of the first switching valve in the first bypass piping and upstream of the expansion turbine to increase the pressure of the gas led to the first bypass piping. The first bypass piping is provided with a second bypass piping that bypasses the compressor, and a second switching valve that can switch between a first flow state in which gas is guided to the compressor but no gas is allowed to flow through the second bypass piping, and a second flow state in which gas is allowed to flow through the second bypass piping but no gas is guided to the compressor. The control device is configured to perform a determination process capable of determining whether the main gas piping downstream of the upstream connection point between the main gas piping and the first bypass piping is in an abnormal state. The gas pressure-utilizing storage and discharge equipment according to claim 1 or 2, wherein, in the determination process, the control device determines that the main gas piping is in the abnormal state, in both the storage pressure non-power generation control and the discharge pressure power generation control, switches the first switching valve to the bypass distribution state, switches the second switching valve to the second flow state, and switches the first on-off valve to the first open state.

6. The main gas piping is provided with a pressure regulating device downstream of the downstream connection portion for regulating the secondary pressure of the main gas piping to a set pressure. The gas pressure utilization storage and discharge equipment according to claim 1 or 2, wherein the control device performs the storage pressure non-power generation control and the discharge pressure power generation control so as to maintain the primary side pressure of the pressure regulating device at or above the set pressure.

7. The power load supplied with power from the generator is configured to also be able to receive power from the power grid in the area where the first bypass piping is laid. The control device is configured to receive whether the power demand in the power grid in the area where the first bypass piping is laid is below a predetermined lower limit threshold for power demand. The gas pressure-based storage and discharge equipment according to claim 1 or 2, wherein when the control device receives that the power demand in the power grid is below the lower limit threshold for power demand, it stops at least the storage and non-generation control and supplies power from the power grid to the power load.

8. The system includes a main gas pipe through which gas supplied from the upstream side can pass, and a first bypass pipe through which gas can pass in a manner that bypasses the main gas pipe in the event of an abnormality in the main gas pipe. A first switching valve capable of switching the distribution state of gas supplied from the upstream side between a main distribution state, in which the gas is distributed to the main gas pipe, and a bypass distribution state, in which the gas is distributed to the first bypass pipe. At the inlet of the downstream connection between the first bypass piping and the main gas piping, a first on-off valve is provided that can switch the opening state of the first bypass piping between a first closed opening state, which includes a fully closed state, and a first open opening state, which includes a fully open state. A gas pressure-based storage and discharge method in a gas pressure-based storage and discharge facility comprising an expansion turbine that causes pressurized gas to flow through and expand the first bypass pipe, and a generator that generates electricity using the shaft output of the expansion turbine, A gas pressure utilization storage and discharge method that performs storage and discharge switching control, which involves setting the first switching valve to the bypass distribution state and the first on / off valve to the first closed opening state to store pressure in the first bypass piping and put the expansion turbine into a non-power generation state, and releasing the gas pressure stored in the first bypass piping to put the expansion turbine into a power generation state.

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