A test system and test method for underground compressed gas energy storage cycle

Abstract

This invention discloses an underground compressed gas energy storage cycle testing system and its testing method. The system includes a triaxial geostress loading assembly, a model box, a heat exchanger assembly, a pressurization assembly, and a chamber. The model box is housed within the triaxial geostress loading assembly. The heat exchanger assembly includes an external heat exchanger unit and an internal heat exchanger unit, with the internal unit housed within the model box and connected to the chamber. The chamber, also housed within the model box, is connected to the pressurization assembly. The model box and chamber are filled with a surrounding rock material layer, and the volume of the cavity within the model box is adjustable. The chamber includes a cylindrical lining and first and second flanges positioned at both ends of the cylindrical lining. An air bladder is installed within the cylindrical lining, and the internal heat exchanger unit is placed within the air bladder. The internal heat exchanger unit and the air bladder are connected to their respective external heat exchanger unit and pressurization assembly via corresponding through channels in the second flange. This invention aims to improve testing accuracy.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to an underground compressed air energy storage cycle testing system and its testing method. Background Technology

[0002] Currently, compressed air energy storage technology uses air as a medium to store and release energy. Among these, underground lined chamber gas storage facilities largely eliminate the dependence of compressed air energy storage power plants on specific geological conditions and offer advantages such as long lifespan, large scale, low cost, environmental friendliness, and convenient maintenance. Unlike traditional underground engineering projects that bear static loads without internal pressure, gas storage chambers will endure the cyclic expansion load of high-pressure air throughout their service life, accompanied by repeated temperature fluctuations (10℃~80℃ or higher), i.e., they will be subjected to thermo-pressure cyclic loading. Thermo-pressure cyclic loading is the main cause of problems such as lining rupture, air leakage, and surrounding rock instability in underground compressed air energy storage chambers. Determining the mechanical response and failure characteristics of underground lined chamber gas storage facilities under thermo-pressure cyclic loading can provide a reference for the ultimate pressure assessment and structural safety design of gas storage facilities, which is of great significance for the large-scale construction of compressed air energy storage power plants.

[0003] The existing invention patent with publication number CN116519489A discloses a model test device and method for simulating the deformation and failure of the surrounding rock of a compressed air energy storage tank. It simulates the surrounding rock structure by filling a geophysical model box with similar materials and repeatedly filling and releasing gas into the gas receiving module through a gas supply module to realize the gas filling and releasing cycle simulation of compressed air energy storage. It also intuitively monitors the deformation of the surrounding rock (through camera video acquisition) and obtains the deformation law of the surrounding rock under the gas filling and releasing cycle. However, the physical model box only serves as a container for filling the surrounding rock simulation material and does not have a triaxial geostress loading function. It cannot realize the operation simulation of the compressed air energy storage chamber under different geostress (different burial depth) conditions, and therefore cannot obtain high-precision experimental data, thus failing to achieve effective application. Summary of the Invention

[0004] The main objective of this invention is to provide an underground compressed air energy storage cycle testing system and its testing method, aiming to solve the technical problem of low data accuracy obtained by existing simulation testing devices.

[0005] To achieve the above objectives, the present invention provides an underground compressed gas energy storage cycle testing system, the system comprising a triaxial geostress loading assembly, a model box, a heat exchanger assembly, a pressurization assembly, and a chamber;

[0006] The model box is set in the triaxial geostress loading assembly;

[0007] The heat exchanger assembly includes an outdoor heat exchanger unit and an indoor heat exchanger unit. The indoor heat exchanger unit is installed inside the model box, and the outdoor heat exchanger unit is connected to the chamber.

[0008] The chamber is located inside the model box and is also connected to a pressurization component, which is used to store compressed air energy into the chamber.

[0009] The model box and the cave are also filled with a layer of surrounding rock material, and the volume of the accommodating cavity inside the model box is adjustable;

[0010] The triaxial geostress loading component is used to apply a preset direction stress to the chamber through the model box to simulate the stress on the chamber;

[0011] The chamber includes a cylindrical lining and a first flange and a second flange arranged at both ends of the cylindrical lining. An air bladder is arranged inside the cylindrical lining, and the internal unit of the heat exchanger is placed inside the air bladder.

[0012] The heat exchanger indoor unit and air bag are respectively connected to the corresponding heat exchanger outdoor unit and pressurization assembly through the corresponding through channels in the second flange;

[0013] The two ends of the cylindrical liner are respectively installed in the grooves of the corresponding first flange and second flange, and the thickness of the cylindrical liner is less than the groove gap of the first flange and second flange.

[0014] Optionally, the pressurization assembly includes an air compressor and a pressure control component. The air compressor is used to pressurize the air, and the pressure control component is used to regulate the pressure of the pressurized air to control the air pressure entering the chamber.

[0015] Optionally, the indoor unit of the heat exchanger is connected to the outdoor unit of the heat exchanger via a heat exchange pipe, which passes through the second flange.

[0016] Optionally, the heat exchanger assembly and the pressurization assembly are also connected to the control console.

[0017] Optionally, the first flange and the second flange are fixedly connected to the corresponding surfaces in the model box.

[0018] Optionally, a through channel in the second flange is fitted with a gas filling / draining port, which is used to connect to a corresponding pipeline of the pressurization component.

[0019] Alternatively, the cylindrical lining is cast using a lining casting mold.

[0020] Optionally, the outer surface of the cylindrical lining is provided with multiple temperature sensors and pressure sensing patches arranged in a circumferential and radial direction; the surrounding rock material layer is provided with multiple surrounding rock pressure sensors and temperature sensors buried along soil layers at different depths.

[0021] Furthermore, to achieve the above objectives, the present invention also provides an experimental method for a subsurface compressed air energy storage cycle testing system. This experimental method is applied to the subsurface compressed air energy storage cycle testing system described in any of the above claims. The method includes the following steps:

[0022] Step 1: Collect pressure and temperature data from the inner wall of the lining and transmit them to the control console. The control console will then adjust the inflation rate of the air compressor and adjust the internal temperature of the airbag to the preset value based on the difference between the preset value and the collected value. The air compressor and heat exchanger will be started based on the corresponding parameters until the real-time air pressure inside the airbag reaches the first preset pressure P1, at which point the inflation of the airbag will be stopped.

[0023] Step 2: After inflation is complete, close the inflation and deflation valves tightly. The air will remain inside the lining, and the air storage control will be activated.

[0024] Step 3: When the gas storage control reaches the first preset time t1, acquire the data of the gas pressure sensor inside the cylindrical lining, and open the exhaust valve until the gas pressure inside the cylindrical lining reaches the second preset pressure P2, then close the exhaust valve.

[0025] Step 4: After the exhaust valve closes for the second preset time t2, execute step 1 and record the number of cycles.

[0026] Optionally, in step 2, if the rate of decrease in gas pressure inside the lining is ≥ WMPa / s, a leakage warning is triggered and displayed on the control panel, and gas storage control continues to be executed, where W is the preset leakage warning value of the control panel.

[0027] Beneficial effects:

[0028] (1) The underground compressed air energy storage cycle test system of this invention has a reasonable gap between the flange slots for installing reinforced concrete lining, reserving space for lining expansion and deformation. This allows the flange and model box to bear excessive internal pressure load, avoiding the lining from being tightly locked to the model box. In other words, a non-tightly locked lining installation and fixing method is adopted, reserving reasonable space for lining expansion and deformation, reducing the error in the distribution of air internal pressure load, and improving the accuracy of the test. The highly visualized model box design facilitates direct observation of the surrounding rock deformation. Furthermore, the addition of a heat exchanger function allows for on-demand activation, enabling simulation of air compression heat recovery in actual compressed air energy storage power stations, while simultaneously restoring the true temperature inside the chamber, further increasing the reliability of the temperature and pressure cycle test results.

[0029] (2) In the experimental method of underground compressed gas energy storage cycle test system, more forms of gas filling and releasing can be realized through the gas filling and releasing mode controlled by flow rate and pressure, which can simulate the mechanical and temperature response of gas storage chamber under more working conditions; and a leakage warning function is added so that the operator can detect gas leakage faults in time, realizing intelligent and safe testing. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of an embodiment of the underground compressed gas energy storage cycle testing system of the present invention;

[0031] Figure 2 for Figure 1 A detailed structural diagram of the chamber in the middle;

[0032] Figure 3 A schematic diagram of the lining casting mold;

[0033] Figure 4 This is a schematic diagram of the cylindrical lining after casting.

[0034] Figure 5 This is a simplified flowchart of the temperature and pressure cycle test logic for an experimental method of an underground compressed gas energy storage cycle test system according to the present invention.

[0035] Explanation of icon numbers:

[0036] 1. Triaxial stress loading assembly; 2. Model box; 3. Heat exchanger outdoor unit; 4. Air compressor; 5. Pressure control components; 7. Control console; 8. Heat exchanger indoor unit; 21. Cylindrical lining; 22. Airbag; 23. First flange; 24. Inflation / deflation port; 25. Heat exchange pipes; 26. Second flange.

[0037] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0038] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0039] See Figures 1 to 4 This invention provides an underground compressed gas energy storage cycle testing system, the system comprising a triaxial geostress loading assembly 1, a model box 2, a heat exchanger assembly, a pressurization assembly, and a chamber; wherein, the model box 2 is disposed within the triaxial geostress loading assembly 1, the triaxial geostress loading assembly 1 being a hydraulic cylinder having three axes (x, y, and z), such as... Figure 1 As shown, the four sides (left side, right side, top, and rear) of the model box 2 are subjected to hydraulic cylinder stress in three directions. Each hydraulic cylinder is started and stopped by a controller. Preferably, each controller is integrated into the corresponding loading control component.

[0040] The heat exchanger assembly includes an outdoor heat exchanger unit 3 and an indoor heat exchanger unit 8. The indoor heat exchanger unit 8 is installed inside the model box 2, and the outdoor heat exchanger unit 3 is connected to the chamber. The chamber is installed inside the model box 2 and is connected to the outdoor heat exchanger unit 3 and the pressurization assembly. The pressurization assembly is used to store compressed air energy in the chamber. The model box 2 and the chamber are also filled with a layer of surrounding rock material. The volume of the cavity inside the model box 2 is adjustable, that is, the volume of the cavity inside the model box 2 can be changed by moving at least one of the left, right, upper, and rear surfaces of the model box 2. Specifically, the triaxial stress loading assembly 1 applies a preset direction stress to the chamber through the model box 2 and the surrounding rock material layer in sequence, thereby simulating the actual stress of the chamber.

[0041] Meanwhile, the chamber includes a cylindrical lining 21 and a first flange 23 and a second flange 26 arranged at both ends of the cylindrical lining 21. An air bladder 22 is arranged inside the cylindrical lining 21, and the heat exchanger internal unit 8 is placed inside the air bladder 22. The heat exchanger internal unit 8 and the air bladder 22 are respectively connected to the corresponding heat exchanger external unit 3 and pressurization assembly through the corresponding through channels in the second flange 26. Furthermore, by pre-installing the heat exchanger internal unit in the air bladder and combining it with the heat exchanger external unit outside the chamber, heat recovery of the gas inside the gas storage chamber is realized, as well as cooling. The connection with the pressurization assembly is also set up to simulate the mechanical properties of the gas storage chamber under more working conditions.

[0042] Furthermore, such as Figure 2 As shown, the two ends of the cylindrical lining 21 are respectively installed in the slots of the corresponding first flange 23 and second flange 26. That is, the cylindrical lining 21 and the flanges at both ends are connected by a snap-fit ​​connection, avoiding the combination of flanges and screws used in the prior art, which can cause the space of the screws to affect the force and force transmission between the surrounding rock layer and the lining during triaxial loading, and reduce the accuracy of the test. Preferably, the thickness of the cylindrical lining 21 is set to be less than the gap between the slots of the first flange 23 and the second flange 26. After installation, there is still a small gap between the lining and the outer slot, which ensures that the lining can be basically fixed in the flange slot, and there is still a small displacement space, so as not to lock with the front and rear plates of the model box. This structure allows the air internal pressure expansion force to be directly borne by the lining, and the model box plate will not share the air expansion load due to the tight constraint of the flange and the lining, thereby reducing the experimental error.

[0043] Furthermore, the pressurization assembly includes an air compressor 4 and a pressure control component 5. The air compressor 4 is used to pressurize the air, and the pressure control component 5 is used to regulate the pressure of the pressurized air to control the air pressure entering the chamber. Preferably, the air compressor 4 is also electrically connected to a control console 7, which can display and control the pressure range output by the air compressor 4; more preferably, the air pressure range is 0.101–30 MPa, and the control accuracy is less than 5‰.

[0044] Furthermore, the indoor unit 8 and the outdoor unit 3 of the heat exchanger are connected via a heat exchange pipe 25, which passes through the second flange 26. Preferably, the temperature range regulated by the heat exchanger assembly is 20–100°C, with a regulation accuracy of less than 1%. More preferably, the heat exchanger assembly is also electrically connected to the control console 7, thereby enabling temperature control of the heat exchanger assembly through the control console 7, thus increasing the amount of experimental data under the specified temperature conditions.

[0045] Furthermore, the first flange 23 and the second flange 26 are respectively fixedly connected to the corresponding surfaces in the model box 2.

[0046] Furthermore, a through channel in the second flange 26 is fitted with a gas filling / draining port 24, which is used to connect to the pressure pipeline of the pressurization component. An exhaust valve 6 is also connected in the pressure pipeline, which is used to perform a pressure relief operation after the test.

[0047] Furthermore, in practical applications, the cylindrical lining 21 is cast using a lining casting mold. Specifically, the chamber lining model is cast according to the experimental requirements. For example, if the chamber is designed with an outer diameter of 400mm and an inner diameter of 350mm, the casting mold is as follows: Figure 3 As shown, its metal outer and inner walls are vertically installed on the base slots, forming a hollow cylindrical cavity. A pre-woven steel mesh is placed inside the cavity, positioned centrally between the inner and outer walls. Concrete is then poured into the mesh cavity, followed by curing and demolding. The completed reinforced concrete lining is shown in the image. Figure 4 As shown, before the experiment, an uninflated airbag was placed inside the lining cavity, and then the lining was installed into the triaxial geostress model box using the corresponding flanges. The flanges were fixed to the front and rear plates of the model box using four bolt holes, resulting in the final product shown below. Figure 2 The chamber structure shown.

[0048] Furthermore, multiple temperature sensors and circumferential and radial pressure sensing patches are arranged on the outer surface of the cylindrical lining 21, and multiple surrounding rock pressure sensors and temperature sensors are buried along different depths of the surrounding rock material layer. The temperature sensors and pressure sensing patches are used to monitor the temperature and pressure changes on the outer surface of the cylindrical lining 21 and within the surrounding rock material layer in real time during the test. Preferably, corresponding temperature and pressure sensors are also provided on the inner wall of the cylindrical lining 21 to detect the temperature and pressure within the cylindrical lining 21 in real time. More preferably, the aforementioned temperature and pressure sensors are electrically connected to the control console 7, enabling the control console 7 to record temperature and pressure changes throughout the entire test process for further control.

[0049] Furthermore, the side of the model box 2 closest to the operator is made visible, thereby enabling a more intuitive observation of the deformation of the surrounding rock material layer during the experiment.

[0050] Furthermore, the surrounding rock material layer is made of sand, gypsum and fly ash in a certain proportion, and the surrounding rock material layer is filled into the model box after the sensor detection equipment is deployed before the specific test, and several surrounding rock pressure and temperature sensors are buried along different soil layers during the filling process.

[0051] Furthermore, the system is also equipped with a video acquisition component, which is used to capture changes in the surrounding rock during the experiment to improve the visualization of surrounding rock deformation.

[0052] Furthermore, to achieve the above objectives, the present invention also provides an experimental method for a subsurface compressed gas energy storage cycle testing system. This experimental method is applied to any of the subsurface compressed gas energy storage cycle testing systems described above, and the method includes the following steps:

[0053] Step 1: Collect pressure and temperature data from the inner wall of the lining and transmit them to the control console. The control console will then adjust the inflation rate of the air compressor and the temperature inside the airbag to the preset value based on the difference between the preset value and the collected value. The air compressor and the heat exchanger will be started based on the corresponding parameters until the real-time air pressure inside the airbag reaches the first preset pressure P1, at which point the inflation of the airbag will be stopped.

[0054] Specifically, before collecting data from the inner wall of the lining, the applied ground stress value needs to be set according to the experimental requirements. This is achieved by loading the lining with a triaxial ground stress loading component. For example, the vertical ground stress value σ0 and the horizontal lateral pressure coefficient α are set, where the horizontal ground stress σ = α * σ0. The vertical ground stress value σ0 = γgh is taken, where γ is the unit weight of common soil, g is taken as 9.8 N / g, and h is the burial depth of the gas storage tank. Simultaneously, the horizontal lateral pressure coefficient α is taken as 1. Once the value collected by the pressure sensor on the lining surface reaches the preset ground stress value, it indicates that the ground stress condition has been successfully applied, and the loading cylinder will continue to apply force to maintain the preset ground stress. The corresponding parameters in the pressurization component and heat exchanger component are also preset according to requirements: including inflation mode parameters, deflation mode parameters, gas storage time, cycle interval time, number of cycles, gas storage pressure P1, deflation pressure P2, and leakage warning value W. After setting, the temperature and pressure cycle test begins, such as... Figure 5 The diagram illustrates the temperature and pressure cycling test logic. Preferably, all monitoring devices are turned on and the camera is activated for video capture before the test begins.

[0055] The inflation control system involves the control console inflating the airbag according to a set gas flow rate. It then collects real-time data from pressure and temperature sensors installed on the inner wall of the lining. After receiving the data, the control console's processing module, based on the difference between the preset and collected values, commands the air compressor to adjust the inflation rate. If the temperature inside the chamber is higher than the preset storage temperature, the control console commands the heat exchanger to adjust the temperature to the preset value. If the air pressure injected into the simulated chamber has reached the preset storage pressure P1, the air compressor and heat exchanger stop operating; otherwise, inflation continues.

[0056] Step 2: After inflation is complete, close the inflation and deflation valves tightly, and the air will be retained in the lining. This will activate the air storage control. If the rate of decrease in air pressure inside the lining is ≥ WMPa / s, a leakage warning will be triggered on the control panel and displayed. The air storage control will continue to be executed, where W is the preset leakage warning value of the control panel.

[0057] Step 3: When the gas storage control reaches the first preset time t1, acquire the data of the gas pressure sensor inside the cylindrical lining, and open the exhaust valve until the gas pressure inside the cylindrical lining reaches the second preset pressure P2, then close the exhaust valve.

[0058] Step 4: After the exhaust valve closes for the second preset time t2, execute Step 1 and record the number of cycles, thus starting the cycle control. If a leakage warning is triggered, mark the current cycle number and continue the original cycle; if the operator manually ends the current cycle, the control panel records the current cycle number, sequentially commands the heat exchanger and air compressor to shut down, commands the exhaust device to release air at the default (safe) exhaust rate to standard atmospheric pressure, and then stops.

[0059] Furthermore, after the experimental loading scheme was completed, the air pressure was unloaded to atmospheric pressure, the equipment was returned to its original position, and the model was removed. The collected data was exported and processed.

[0060] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0061] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0062] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. An underground compressed gas energy storage cycle testing system, characterized in that, The system includes a triaxial geostress loading assembly (1), a model box (2), a heat exchanger assembly, a pressurization assembly, and a chamber; The model box (2) is set in the triaxial geostress loading assembly (1); The heat exchanger assembly includes an external heat exchanger unit (3) and an internal heat exchanger unit (8). The internal heat exchanger unit (8) is installed inside the model box (2), and the external heat exchanger unit (3) is connected to the chamber. The chamber is located inside the model box (2) and is also connected to the pressurization component, which is used to store compressed air energy into the chamber; The model box (2) and the chamber are also filled with a layer of surrounding rock material, and the volume of the accommodating cavity inside the model box (2) is adjustable; The triaxial geostress loading component (1) is used to apply a preset direction stress to the chamber through the model box (2) and the surrounding rock material layer to simulate the actual stress on the chamber; The chamber includes a cylindrical lining (21) and a first flange (23) and a second flange (26) arranged at both ends of the cylindrical lining (21). An air bladder (22) is arranged inside the cylindrical lining (21), and the heat exchanger internal unit (8) is placed inside the air bladder (22). The heat exchanger indoor unit (8) and airbag (22) are respectively connected to the corresponding heat exchanger outdoor unit (3) and pressurization assembly through the corresponding through channels in the second flange (26); The two ends of the cylindrical liner (21) are respectively installed in the slots of the corresponding first flange (23) and second flange (26), and the thickness of the cylindrical liner (21) is less than the gap between the slots of the first flange (23) and the second flange (26).

2. The underground compressed gas energy storage cycle testing system as described in claim 1, characterized in that, The pressurization assembly includes an air compressor (4) and a pressure control component (5). The air compressor (4) is used to pressurize the air, and the pressure control component (5) is used to regulate the pressure of the pressurized air to control the air pressure entering the chamber.

3. The underground compressed gas energy storage cycle testing system as described in claim 1, characterized in that, The heat exchanger indoor unit (8) and the heat exchanger outdoor unit (3) are connected by a heat exchange pipe (25), which passes through the second flange (26).

4. The underground compressed gas energy storage cycle testing system as described in claim 1, characterized in that, The heat exchanger assembly and the pressurization assembly are also connected to the control console (7).

5. The underground compressed gas energy storage cycle testing system as described in claim 1, characterized in that, The first flange (23) and the second flange (26) are fixedly connected to the corresponding surfaces in the model box (2).

6. The underground compressed gas energy storage cycle testing system as described in claim 1, characterized in that, A through channel in the second flange (26) is fitted with a gas filling / draining port (24), which is used to connect to the corresponding pipeline of the pressurization assembly.

7. The underground compressed gas energy storage cycle testing system as described in any one of claims 1 to 6, characterized in that, The cylindrical lining (21) is cast using a lining casting mold.

8. The underground compressed gas energy storage cycle testing system as described in claim 7, characterized in that, Multiple temperature sensors and circumferential and radial pressure sensor patches are arranged on the outer surface of the cylindrical lining (21); multiple surrounding rock pressure sensors and temperature sensors are buried along soil layers at different depths in the surrounding rock material layer.

9. An experimental method for a subsurface compressed air energy storage cycle testing system, wherein the experimental method for the subsurface compressed air energy storage cycle testing system is applied to the aforementioned subsurface compressed air energy storage cycle testing system, characterized in that, The method Includes the following steps, Step 1: Collect pressure and temperature data from the inner wall of the lining and transmit them to the control console. The control console will then adjust the inflation rate of the air compressor and adjust the internal temperature of the airbag to the preset value based on the difference between the preset value and the collected value. The air compressor and heat exchanger will be started based on the corresponding parameters until the real-time air pressure inside the airbag reaches the first preset pressure P1, at which point the inflation of the airbag will be stopped. Step 2: After inflation is complete, close the inflation and deflation valves tightly. The air will remain inside the lining, and the air storage control will be activated. Step 3: When the gas storage control reaches the first preset time t1, acquire the data of the gas pressure sensor inside the cylindrical lining, and open the exhaust valve until the gas pressure inside the cylindrical lining reaches the second preset pressure P2, then close the exhaust valve. Step 4: After the exhaust valve closes for the second preset time t2, execute step 1 and record the number of cycles.

10. The experimental method for the underground compressed gas energy storage cycle testing system as described in claim 9, characterized in that, In step 2, if the rate of decrease in air pressure inside the lining is ≥ WMPa / s, a leakage warning is triggered and displayed on the control console, and the gas storage control continues to be executed, where W is the preset leakage warning value of the control console.

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