A method for matching design of salt cavern compressed air energy storage pressure installation

Abstract

The application provides a salt cavern compressed air energy storage pressure matching design method, which comprises the following steps: S1, collecting existing salt cavern data, carrying out existing salt cavern screening work, and selecting a salt cavity; S2, according to the brine extraction history and salt layer grade of the selected salt cavity, calculating the available space of the selected salt cavity; S3, according to the drilling and completion data, obtaining the burial depth of the salt cavity, and according to the salt cavern storage pressure design method, calculating the suitable pressure range of the burial depth of the salt cavity; S4, using the available space and pressure value of the salt cavity, calculating the available space corresponding to the cavern storage value of the salt cavity; S5, according to the expander efficiency, calculating the power generation capacity, and according to the ground conditions and power station application scene, determining the installed capacity and power generation time of the power station. The application has the beneficial effects that: the application takes the salt cavity as the design core, and carries out the ground equipment design work only under the premise of being feasible underground, which fully and reasonably utilizes the gas storage function of the salt cavity, and the power station operation pressure is also the optimal pressure of the stability of the salt cavity, and the matching of the power station unit equipment and the storage is improved.

Description

Technical Field

[0001] This invention relates to the field of salt cavern compressed air energy storage, and mainly to a design method for matching the pressure of existing salt cavern compressed air energy storage units. Background Technology

[0002] Large-scale compressed air energy storage power plants require enormous gas storage space. Salt caverns offer advantages such as good sealing, high storage pressure, and low construction costs, making them a viable solution to the large-capacity gas storage problem in large-scale compressed air energy storage power plants. my country is rich in salt cavern resources, with approximately 1.3 × 10⁻⁶ existing salt caverns. 8 m 3 Currently, only 0.2% of salt caverns nationwide are in use, leaving the vast majority of salt cavern resources idle and indicating a huge untapped potential. Modifying existing salt caverns can effectively save construction time for compressed air energy storage power stations and also realize the reuse of idle underground resources.

[0003] Newly built compressed air storage facilities are designed based on the ground-based installation requirements and operating pressure range, selecting suitable geological conditions and setting storage capacity accordingly. In contrast, the geological conditions and storage capacity of existing salt caverns are already limited. Constructing a compressed air energy storage power station requires designing suitable pressures and matching them with ground-based installations based on the existing salt caverns. This is particularly important in the design of compressed air energy storage power stations, directly affecting the efficiency and economy of the power station. Summary of the Invention

[0004] To improve the compatibility of existing salt caverns with the pressure and installed capacity of generating units, this invention proposes a design method for pressure and installed capacity matching of existing salt cavern compressed air energy storage. By comprehensively evaluating the geological conditions and storage capacity of existing salt caverns, a suitable pressure range is determined, and the corresponding installed capacity and power generation duration on the ground are established, thereby improving the compatibility of the entire power station system.

[0005] The objective of this invention is achieved through the following technical solution: A method for matching the pressure of existing salt cavern compressed air energy storage systems, comprising the following steps:

[0006] S1. Collect data on existing salt caverns, conduct screening of existing salt caverns, and select salt caverns;

[0007] S2. Based on the brine extraction history and salt layer grade of the selected salt cavity, calculate the usable space of the selected salt cavity;

[0008] S3. Based on the drilling and completion data, determine the burial depth of the salt cavity, and calculate the appropriate pressure range for the burial depth of the salt cavity according to the salt cavern storage pressure design method.

[0009] S4. Using the available space and pressure values ​​of the salt cavity, calculate the cavern storage corresponding to the available space of the salt cavity. value;

[0010] S5. Calculate the power generation capacity based on the expander efficiency, and determine the installed capacity and power generation duration of the power station based on the ground conditions and the application scenario of the power station.

[0011] Furthermore, in step S1, the collected regional geological data, distribution of salt cavity well locations, and history of salt cavity mining are analyzed. Based on the salt cavity screening principles, existing salt cavities with simple structures, stable and independent mining are selected.

[0012] Further, in step S2, the drilling and completion data of the selected salt cavity are analyzed to obtain the salt layer, interlayer thickness, and soluble content corresponding to the salt cavity; based on the brine extraction history of the salt cavity, the usable space of the selected salt cavity is calculated; the specific calculation method is as follows:

[0013]

[0014] Where V is the usable space of the salt cavity, V r Let m be the volume of dissolution in the salt cavity. r ρ is the mass of soluble matter, a is the density, a is the percentage of soluble matter obtained from the salt layer, and κ is the combined coefficient of fragmentation and expansion.

[0015] Furthermore, in step S3, the pressure is designed using a pressure gradient of 1.1MPa to 1.5MPa per 100m, and the burial depth is multiplied by the pressure gradient to obtain the appropriate pressure range for the salt cavity.

[0016] Furthermore, in step S4, storage is carried out using a cavern. The value calculation formula, by substituting the available space and pressure value of the salt chamber, yields the storage capacity of the salt chamber within the design pressure range. value;

[0017] Cavern storage The value calculation formula is:

[0018]

[0019] Where, m in C is the inflation rate. p R is the specific heat capacity at constant pressure of compressed air, T is the temperature of compressed air, T0 is the ambient temperature, R is the gas constant, P is the pressure of compressed air, and P0 is the ambient pressure.

[0020] Furthermore, considering the temperature changes during compressed air storage in the salt chamber, the usable space and pressure range of the salt chamber under isothermal conditions are calculated. The value is:

[0021]

[0022] Where P1 is the minimum operating pressure of the power plant, and P2 is the maximum operating pressure of the power plant.

[0023] The beneficial effects of this invention are as follows: This invention uses a salt cavity as the core design element, and only proceeds with the design of surface equipment when underground feasibility is guaranteed. This fully and rationally utilizes the gas storage function of the salt cavity, and the power station's operating pressure is also the optimal pressure for salt cavity stability, improving the compatibility between the power station's generating units and the storage facility. This method can be extended to the construction of compressed air energy storage in existing storage facilities, including abandoned mine shafts, aquifers, and hydroelectric caverns, with only slight differences in the estimation of cavern capacity and the design of operating pressure. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art or ordinary skills, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the process of the present invention.

[0026] Figure 2 This is a schematic diagram of the usable space of the salt cavity in this invention.

[0027] Explanation of reference numerals in the attached diagram: 1-Useable space in the salt chamber (capacity), 2-Sediment, 3-Salt layer, 4-Interlayer. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0029] like Figure 1 As shown, this invention provides a design method for matching the pressure of existing salt cavern compressed air energy storage systems, comprising the following steps:

[0030] S1. Collect data on existing salt caverns, conduct screening of existing salt caverns, and select salt caverns;

[0031] The existing salt caverns of a certain salt enterprise in a certain region were screened: the collected regional geological data, distribution of salt cavern well locations, and history of salt cavern mining were analyzed. Based on the salt cavern screening principles, existing salt caverns with simple structures, stable mining operations, and independent operation were selected.

[0032] S2. Based on the brine extraction history and salt layer grade of the selected salt cavity, calculate the usable space (capacity) of the selected salt cavity; such as Figure 2 As shown, a salt cavity is selected, comprising usable space 1, sediment 2, salt layer 3, and interlayer 4. Drilling and completion data for the selected salt cavity are analyzed to obtain the corresponding salt layer, interlayer thickness, and soluble content. Based on the brine extraction history of this salt cavity, the cavity volume is estimated. The specific calculation method is as follows:

[0033] Using the mass conservation method, the content of soluble matter extracted from the total brine volume is converted and then recalculated into the dissolution volume of the cavity:

[0034]

[0035] Where m r The volume calculated based on the mass of soluble matter extracted from brine is typically 300g NaCl and 47.6g Na₂SO₄ per cubic meter of brine. This volume represents the dissolution volume, not the truly usable volume. Due to the presence of mud layers and other insoluble substances during deposition, these layers remain in the cavity during dissolution, occupying space. The truly usable space V of the salt cavity is:

[0036]

[0037] 'a' is the percentage of soluble matter obtained from the salt layer; κ is the combined coefficient of fragmentation and expansion, around 1.5-3 (obtained experimentally). Based on the above process, the usable space of the solution cavity, i.e., the reservoir capacity, can be calculated.

[0038] S3. Based on the drilling and completion data, determine the burial depth of the salt cavity, and calculate the appropriate pressure range for the burial depth of the salt cavity according to the salt cavern storage pressure design method.

[0039] As a preferred implementation scheme, the pressure is designed using a pressure gradient of 1.1 to 1.5 MPa per 100 m, and the appropriate pressure range for the salt cavern is obtained by multiplying the burial depth by the pressure gradient.

[0040] S4. Using the available space (capacity) and pressure value of the salt cavity, calculate the cavern storage corresponding to the available space of the salt cavity. value;

[0041] Storage in caverns The formula for calculating the value is used, by substituting the storage capacity and pressure values, to calculate the storage capacity of the salt chamber within the design pressure range. value.

[0042] Cavern storage Value calculation formula:

[0043]

[0044] In the formula m in C is the inflation rate. p ρ is the specific heat capacity of compressed air at constant pressure, J / (kg·K); T is the temperature of compressed air, K; T0 is the ambient temperature, 298K; R is the gas constant, J / (kg·K); P is the pressure of compressed air, Pa; P0 is the ambient pressure, 0.1MPa.

[0045] When considering the temperature changes of compressed air stored in a salt cavity, the cavern thermodynamic equations need to be introduced. Here, we can simplify the consideration of cavern storage under isothermal conditions. value;

[0046]

[0047] m=ρV

[0048]

[0049] This leads to the storage conditions under isothermal conditions within a specific storage capacity and pressure range. The value is:

[0050]

[0051] Here, P1 is the minimum operating pressure of the power plant (Pa); P2 is the maximum operating pressure of the power plant (Pa).

[0052] S5. Calculate the power generation capacity based on the expander efficiency. Determine the installed capacity and power generation duration based on ground conditions, such as the status of the transmission substation and site conditions.

[0053] Example:

[0054] A plan is underway to construct a compressed air energy storage power station using existing salt caverns in a mining area. Relevant data on salt wells has been collected from a local salt company. Based on the requirements and the results of salt cavern selection, the design of the ground-based installed capacity and power generation duration is now being developed.

[0055] 1. By analyzing multiple salt chambers of the salt enterprise, one salt chamber was selected that was relatively independent, had no abnormalities in mining, had a stable geological structure, and was far away from faults.

[0056] 2. Analysis of drilling and completion geological data for the selected salt cavity confirmed that the total thickness of the salt layer at the burial depth is 90m, the total thickness of the interlayer is 20m, and the overall soluble content (a) is approximately 64%. A total of 1.9 million tons of NaCl and Na₂SO₄ were extracted from the salt cavity. This was determined by dividing the extracted mass by the density of the salt (2.16 g / cm³). 3 The dissolution volume V was obtained. r It is 879,630 m³ 3 .

[0057] The interlayer fragmentation-expansion coefficient κ is 1.7, through... The calculated net space of the salt cavity is 533,200 m². 3 .

[0058] 3. The salt cavity is buried at a depth of 1460m to 1550m underground. Based on the pressure gradient of 1.1 to 1.5MPa per 100m, the average depth of 1500m is used for calculation, and the pressure range is obtained as 16.5MPa to 22.5MPa.

[0059] 4. Round the pressure value close to the average value to 17-22 MPa, input the storage capacity value, and calculate the cavern storage. The value is 4086.25 WMh.

[0060] 5. Considering the expander's efficiency of 0.88, the actual power generation capacity is 3596 MWh. The surrounding substation is 220 kV, which can meet the grid connection requirements for large-scale installations. There are various combinations of installed capacity and power generation time. Depending on the application requirements of the energy storage power source, such as for peak shaving, generating power for 6 hours, the installed capacity could be determined to be 600 MW.

[0061] This method can also be used in steps 4 and 5 to adjust and optimize the pressure and installed capacity. For example, the pressure can be moved closer to the middle value, reducing the pressure variation range, and set to 18-21 MPa, which can be calculated. The value is then used to determine the combination of installed capacity and power generation time.

[0062] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for matching the pressure of existing salt cavern compressed air energy storage units, characterized in that: The steps include the following: S1. Collect data on existing salt caverns, conduct screening of existing salt caverns, and select salt caverns; S2. Based on the brine extraction history and salt layer grade of the selected salt cavity, calculate the usable space of the selected salt cavity; In step S2, the drilling and completion data of the selected salt cavity are analyzed to obtain the corresponding salt layer, interlayer thickness, and soluble content; based on the brine extraction history of the salt cavity, the usable space of the selected salt cavity is calculated; the specific calculation method is as follows: ， ， in, This provides usable space for the salt cavity. This represents the dissolution volume of the salt cavity. For the mass of soluble matter, For density, Based on the percentage of soluble matter obtained from the salt layer It is a combined coefficient of fragmentation and expansion; S3. Based on the drilling and completion data, determine the burial depth of the salt cavity, and calculate the appropriate pressure range for the burial depth of the salt cavity according to the salt cavern storage pressure design method. S4. Using the available space and pressure value of the salt cavity, calculate the cavern storage value corresponding to the available space of the salt cavity. S5. Calculate the power generation capacity based on the expander efficiency, and determine the installed capacity and power generation duration of the power station based on the ground conditions and the application scenario of the power station.

2. The design method for matching the pressure of existing salt cavern compressed air energy storage units according to claim 1, characterized in that: In step S1, the collected regional geological data, distribution of salt cavity well locations, and history of salt cavity mining are analyzed. Based on the salt cavity screening principle, existing salt cavities with simple structures, stable and independent mining are selected.

3. The design method for matching the pressure of existing salt cavern compressed air energy storage units according to claim 1, characterized in that: In step S3, the pressure is designed using a pressure gradient of 1.1MPa to 1.5MPa per 100m. The burial depth is multiplied by the pressure gradient to obtain the appropriate pressure range for the salt cavity.

4. The design method for matching the pressure of existing salt cavern compressed air energy storage units according to claim 1, characterized in that: In step S4, the storage capacity of the salt chamber within the design pressure range is calculated by substituting the available space and pressure value of the salt chamber into the formula for calculating the storage capacity of the salt chamber using the formula for calculating the storage capacity of the salt chamber within the design pressure range. The formula for calculating the storage value of a cavern is: ； in, Inflation rate, Let T be the specific heat capacity at constant pressure of compressed air, T be the temperature of compressed air, T0 be the ambient temperature, R be the gas constant, and P be the pressure of compressed air. Due to environmental pressures.

5. The design method for matching the pressure of existing salt cavern compressed air energy storage units according to claim 4, characterized in that: When considering the temperature change of compressed air stored in the salt chamber, the storage capacity of the salt chamber under isothermal conditions is calculated as follows: ； Where P1 is the minimum operating pressure of the power plant, and P2 is the maximum operating pressure of the power plant.

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