Method and device for measuring steam leakage amount of high and intermediate pressure combined cylinder of reheating steam turbine

Abstract

The invention discloses a method and device for measuring the steam leakage amount of a high-intermediate-pressure combined cylinder of a reheating steam turbine, and the method comprises the steps: setting the opening degree of a steam inlet control valve of an intermediate-pressure cylinder of the steam turbine to be 100%, keeping the opening degree unchanged, putting a sequence valve of a high-pressure cylinder into operation, keeping the last valve of the high-pressure steam inlet control valve to be closed, keeping the rest valves to be fully opened, and keeping a steam supplementing valve to be fully closed; the test result is kept unchanged during the test period; through two test working conditions with different steam parameters, two curves of change of the efficiency of the intermediate-pressure cylinder along with the cylinder closing steam leakage amount are obtained through calculation; the intersection point of the two curves of the medium-pressure cylinder efficiency changing along with the cylinder combination steam leakage amount is obtained, and the intersection point is the actual cylinder combination shaft seal steam leakage amount. The device comprises a valve setting unit, a calculation unit and an intersection point acquisition unit. The device has wide applicability and can be popularized and used in a large range.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation testing technology, specifically relating to a method and apparatus for determining the steam leakage of the high-pressure combined cylinder of a reheat steam turbine. Background Technology

[0002] For steam turbines with combined high- and intermediate-pressure cylinders, the shaft seals at the cylinder junction are prone to severe wear, leading to increased steam leakage at this junction and directly impacting the intermediate-pressure cylinder efficiency and the turbine's heat rate. However, due to the unique location of this area, direct measurement with orifice plates is not possible. Turbine testing units typically employ a "variable-temperature method": maintaining the main steam temperature near the design value, lowering the reheat steam temperature for test condition one; then restoring the reheat steam temperature to near the design value, lowering the main steam temperature for test condition two. After testing, the cylinder leakage rate (the ratio of leakage flow at the cylinder junction to reheat steam flow) is calculated using the linear intersection method. This method is widely used and is a relatively mature testing technique.

[0003] However, as the unit ages, adjusting its steam temperature parameters becomes increasingly difficult. In actual testing, there are situations where the turbine cannot meet the requirements of the "variable temperature method": when the main steam temperature (or reheat steam temperature) is reduced for testing, the main steam temperature (or reheat steam temperature) cannot be restored to the design temperature in a short period of time, and the reheat steam temperature (or main steam temperature) cannot be reduced in a short period of time, making the test difficult to conduct.

[0004] The invention patent with authorization announcement number CN 104535326 B discloses a method for measuring the leakage of the bridge steam seal in a reheat-type combined-cylinder steam turbine. The core of this invention involves using the emergency venting system's discharge channel in the middle section of the bridge steam seal connected to the high-pressure inner cylinder of the steam turbine. Temperature, pressure, and flow meters are added, and the venting valve is opened to measure steam parameters. The leakage flow rate of the bridge steam seal is accurately determined using the Martin formula. The main drawbacks of this design are: First, this method requires additional pressure, temperature, and flow measurement points and valves, significantly increasing testing costs. Second, the corresponding steam pipes in the shaft seal system typically have small diameters, making it difficult to install flow measurement points in practice when using emergency venting pipes. Third, the calculation in this invention uses the Martin formula, where the constant K is a constant for steam seals of the same type with the same gap and radius. However, changes in shaft seal leakage are caused by wear and increased gap in the shaft seal, meaning the actual seal gap and radius have changed and become unknown. Therefore, the constant K used in the calculation is not accurate. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the prior art by providing a method and apparatus for measuring steam leakage in the high- and intermediate-pressure combined cylinder of a reheat steam turbine.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for determining the steam leakage of the intermediate and high-pressure combined cylinder of a reheat steam turbine, comprising:

[0008] 1) Set the opening of the steam inlet regulating valve of the intermediate pressure cylinder of the steam turbine to 100% and keep it unchanged. Put the high pressure cylinder sequence valve into operation, keep the last valve of the high pressure steam inlet regulating valve closed, the remaining valves fully open, and the make-up steam valve fully closed, and keep it unchanged during the test.

[0009] 2) Through two test conditions with different steam parameters, two curves were obtained by calculation showing the change of intermediate pressure cylinder efficiency with cylinder leakage.

[0010] 3) Obtain the intersection of the two curves showing the change in efficiency of the intermediate-pressure cylinder with the leakage of steam during cylinder connection. This intersection is the actual leakage of steam from the shaft seal during cylinder connection.

[0011] A further improvement of the present invention is that, in step 1), for a unit with four high-pressure steam inlet valves, the test results of the turbine three-valve full-open test conducted concurrently are used as test condition one; or for a unit with six high-pressure steam inlet valves, the test results of the turbine five-valve full-open test conducted concurrently are used as test condition one.

[0012] A further improvement of the present invention is that, in step 1), the reheat steam temperature is reduced by 20°C to 30°C from the design temperature by the operator adjusting the flue gas parameters on the boiler side or by spraying water to cool it down, which is used as test condition two.

[0013] A further improvement of the present invention is that, in step 2), the main steam pressure, main steam temperature, regulating stage pressure, regulating stage temperature, reheat steam pressure, reheat steam temperature, intermediate pressure cylinder exhaust pressure, and intermediate pressure cylinder exhaust temperature are obtained by testing, and the corresponding enthalpy and entropy values ​​of the main steam, regulating stage steam, high pressure cylinder exhaust, reheat steam, and intermediate pressure cylinder exhaust are obtained by consulting the water and steam physical property parameter table.

[0014] A further improvement of the present invention is that, in step 2), it is assumed that the proportion of the combined cylinder leakage to the reheat steam flow is 0%, that is, there is no combined cylinder leakage. Then, the enthalpy of the intermediate pressure cylinder inlet steam is equal to the enthalpy of the reheat steam. The intermediate pressure cylinder efficiency is further calculated as follows: intermediate pressure cylinder efficiency = (actual enthalpy drop at the inlet and outlet of the intermediate pressure cylinder / isentropic enthalpy drop at the inlet and outlet of the intermediate pressure cylinder) * 100%.

[0015] A further improvement of the present invention is that, in step 2), assuming that the leakage of steam in the combined cylinder accounts for 8% of the reheat steam flow rate, the enthalpy of the intermediate pressure cylinder inlet steam is calculated as (enthalpy of reheat steam + enthalpy of steam after regulating stage * 8%) / 108%. The intermediate pressure cylinder efficiency is further calculated as follows: intermediate pressure cylinder efficiency = (actual enthalpy drop of intermediate pressure cylinder steam inlet and outlet / isentropic enthalpy drop of intermediate pressure cylinder steam inlet and outlet) * 100%.

[0016] A further improvement of this invention is that, for test condition one, after step 2), the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 0% of the reheat steam flow rate, and the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 8% of the reheat steam flow rate are obtained, thus obtaining a linear relationship between the intermediate-pressure cylinder efficiency and the combined cylinder leakage rate ratio for test condition one; for test condition two, after step 2), the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 0% of the reheat steam flow rate, and the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 8% of the reheat steam flow rate are obtained, thus obtaining a linear relationship between the intermediate-pressure cylinder efficiency and the combined cylinder leakage rate ratio for test condition two.

[0017] A further improvement of the present invention is that, in step 3), the linear relationship between the intermediate pressure cylinder efficiency and the proportion of combined cylinder leakage in test conditions one and test conditions two is plotted on the same XY coordinate system, resulting in two intersecting straight lines. The intersection point corresponds to the actual intermediate pressure cylinder efficiency and the actual proportion of combined cylinder leakage to the reheat steam flow.

[0018] A device for measuring steam leakage in the high-pressure and intermediate-pressure combined cylinder of a reheat steam turbine, comprising:

[0019] The valve setting unit is used to set the opening of the steam inlet regulating valve of the intermediate pressure cylinder of the steam turbine to 100% and keep it unchanged, put the high pressure cylinder sequence valve into operation, keep the last valve of the high pressure inlet regulating valve closed, the remaining valves fully open, and the make-up steam valve fully closed, and keep it unchanged during the test.

[0020] The calculation unit is used to calculate two curves of the efficiency of the intermediate pressure cylinder as a function of the combined cylinder leakage under two test conditions with different steam parameters.

[0021] The intersection point acquisition unit is used to acquire the intersection point of the two curves showing the change of intermediate pressure cylinder efficiency with cylinder leakage, which is the actual cylinder shaft seal leakage.

[0022] A further improvement of the present invention is that, in the valve setting unit, for a unit with four high-pressure steam inlet regulating valves, the test results of the turbine three-valve full-open test conducted simultaneously are used as test condition one; or for a unit with six high-pressure steam inlet regulating valves, the test results of the turbine five-valve full-open test conducted simultaneously are used as test condition one.

[0023] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0024] This invention provides a method and apparatus for determining the leakage of the intermediate and high-pressure cylinders in a reheat steam turbine. Based on the premise that the opening of the inlet regulating valves and the steam flow rate remain essentially constant, the efficiency of the high and intermediate pressure cylinders remains unchanged. The conventional "variable temperature method" is replaced with a "single variable method," directly using the test results of a steam turbine operating under the conditions of three valves fully open (for units with four inlet regulating valves) or five valves fully open (for units with six inlet regulating valves) conducted concurrently, as test condition one. Test condition two is completed by adjusting the boiler-side flue gas parameters or spraying water to lower the reheat steam temperature by 20℃ to 30℃ compared to the design temperature. Calculations are performed using the two test conditions to obtain the linear relationship between the efficiency of the intermediate pressure cylinder and the proportion of leakage in the cylinder. Plotting the linear relationship between the efficiency of the intermediate pressure cylinder and the proportion of leakage in the cylinder under test conditions one and two on the same XY coordinate system yields two intersecting straight lines; the intersection point of these two lines represents the actual leakage of the cylinder shaft seal.

[0025] In summary, this invention replaces the conventional "variable temperature method" with a "single variable method," which is simple; requires no additional instruments or equipment, resulting in low cost; obtains calculation results through the linear intersection method, a widely used method that ensures accuracy; can also be used with high- and medium-pressure combined-cylinder steam turbines that cannot meet the requirements of the "variable temperature method"; and only requires one steam temperature reduction test, mitigating the impact of special operating conditions on equipment lifespan. Therefore, this invention has broad applicability and can be widely promoted and used. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a rendering of an embodiment of the present invention.

[0028] Figure 2 This is a structural block diagram of a device for measuring steam leakage in the high-pressure and intermediate-pressure cylinders of a reheat steam turbine according to the present invention. Detailed Implementation

[0029] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0030] In the description of this invention, it should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0031] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0033] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0034] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] Example 1

[0036] This invention provides a method for determining the steam leakage of the intermediate and high-pressure combined cylinder of a reheat steam turbine, comprising:

[0037] 1) Set the opening of the steam inlet regulating valve of the intermediate pressure cylinder of the steam turbine to 100% and keep it unchanged. Put the high pressure cylinder sequence valve into operation, keep the last valve of the high pressure steam inlet regulating valve closed, the remaining valves fully open, and the make-up steam valve fully closed, and keep it unchanged during the test.

[0038] 2) Through two test conditions with different steam parameters, two curves were obtained by calculation showing the change of intermediate pressure cylinder efficiency with cylinder leakage.

[0039] 3) Obtain the intersection of the two curves showing the change in efficiency of the intermediate-pressure cylinder with the leakage of steam during cylinder connection. This intersection is the actual leakage of steam from the shaft seal during cylinder connection.

[0040] In step 1) of this embodiment, for a unit with 4 high-pressure steam inlet valves, the test result of the turbine three-valve full-open test conducted at the same time is used as test condition one; or for a unit with 6 high-pressure steam inlet valves, the test result of the turbine five-valve full-open test conducted at the same time is used as test condition one.

[0041] In step 1) of this embodiment, the reheat steam temperature is reduced by 20°C to 30°C from the design temperature by the operator adjusting the boiler side flue gas parameters or spraying water to cool it down, which is the second test condition.

[0042] In step 2) of this embodiment, the main steam pressure, main steam temperature, regulating stage pressure, regulating stage temperature, reheat steam pressure, reheat steam temperature, intermediate pressure cylinder exhaust pressure, and intermediate pressure cylinder exhaust temperature are obtained by testing. The enthalpy and entropy values ​​of the corresponding main steam, regulating stage steam, high pressure cylinder exhaust, reheat steam, and intermediate pressure cylinder exhaust are obtained by consulting the water and steam property parameter table.

[0043] In step 2) of this embodiment, it is assumed that the proportion of the combined cylinder leakage to the reheat steam flow is 0%, that is, there is no combined cylinder leakage. Then the enthalpy of the intermediate pressure cylinder inlet steam is equal to the enthalpy of the reheat steam. The intermediate pressure cylinder efficiency is further calculated as follows: intermediate pressure cylinder efficiency = (actual enthalpy drop at the inlet and outlet of the intermediate pressure cylinder / isentropic enthalpy drop at the inlet and outlet of the intermediate pressure cylinder) * 100%.

[0044] In step 2) of this embodiment, assuming that the combined cylinder leakage accounts for 8% of the reheat steam flow rate, the enthalpy of the intermediate pressure cylinder inlet steam is calculated as (enthalpy of reheat steam + enthalpy of steam after regulating stage * 8%) / 108%. The intermediate pressure cylinder efficiency is further calculated as follows: intermediate pressure cylinder efficiency = (actual enthalpy drop at intermediate pressure cylinder steam inlet and outlet / isentropic enthalpy drop at intermediate pressure cylinder steam inlet and outlet) * 100%.

[0045] In this embodiment, for test condition one, after step 2), the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 0% of the reheat steam flow rate, and the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 8% of the reheat steam flow rate are obtained, thus obtaining a linear relationship between the intermediate-pressure cylinder efficiency and the combined cylinder leakage rate in test condition one; for test condition two, after step 2), the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 0% of the reheat steam flow rate, and the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 8% of the reheat steam flow rate are obtained, thus obtaining a linear relationship between the intermediate-pressure cylinder efficiency and the combined cylinder leakage rate in test condition two.

[0046] In step 3) of this embodiment, the linear relationship between the intermediate pressure cylinder efficiency and the proportion of combined cylinder leakage in test conditions one and test conditions two is plotted on the same XY coordinate system, resulting in two intersecting straight lines. The intersection point corresponds to the actual intermediate pressure cylinder efficiency and the actual proportion of combined cylinder leakage to the reheat steam flow.

[0047] Example 2

[0048] This invention provides a method for determining the leakage of the intermediate and high-pressure cylinders in a reheat steam turbine. This method assumes that the inlet valve opening and steam flow rate remain essentially constant, while the efficiency of the high and intermediate pressure cylinders remains unchanged. During the test, the inlet valve opening of the intermediate pressure cylinder is set to 100% and remains constant. The high-pressure cylinder sequence valves are engaged, maintaining three valves fully open (for units with four inlet valves) or five valves fully open (for units with six inlet valves), while the make-up steam valve is fully closed. Through two test conditions with different steam parameters, the linear relationship between the intermediate pressure cylinder efficiency and the leakage of the cylinders is obtained for two sets of tests. Plotting the linear relationship between the intermediate pressure cylinder efficiency and the proportion of leakage in the cylinders under test conditions one and two on the same XY coordinate system, the two straight lines will intersect at a point, which corresponds to the actual leakage of the cylinder shaft seal.

[0049] In this embodiment, the conventional "variable temperature method" is replaced by the "single variable method". The turbine test results of the three valves fully open (for units with 4 steam inlet valves) or five valves fully open (for units with 6 steam inlet valves) conditions are directly used as test condition one.

[0050] In this embodiment, the test of variable steam temperature can be completed by lowering the reheat steam temperature once (test condition two), which significantly reduces the difficulty of temperature adjustment during the test compared with the conventional "variable temperature method".

[0051] Example 3

[0052] The present invention provides a method for determining the steam leakage of the high- and intermediate-pressure combined cylinder of a reheat steam turbine, the specific implementation steps of which are as follows:

[0053] First, the operators adjust the unit's status to ensure that the opening of the intermediate-pressure cylinder inlet regulating valve remains constant at 100% during the test. The high-pressure cylinder sequence valve is engaged, maintaining three valves fully open (for units with four inlet regulating valves) or five valves fully open (for units with six inlet regulating valves), while the make-up steam valve is fully closed. During the test, the main parameters of the unit are kept stable, and fluctuations in steam pressure and temperature are minimized.

[0054] The turbine test results under the three-valve fully open (for units with four inlet steam control valves) or five-valve fully open (for units with six inlet steam control valves) conditions conducted concurrently are directly used as test condition one. The main steam pressure, main steam temperature, regulating stage pressure, regulating stage temperature, reheat steam pressure, reheat steam temperature, intermediate pressure cylinder exhaust pressure, and intermediate pressure cylinder exhaust temperature measured by the operating instruments (or test instruments) are used for calculation.

[0055] The operating parameters of the unit are adjusted by the operators. By adjusting the flue gas parameters on the boiler side or spraying water to cool down, the reheat steam temperature is reduced by 20℃ to 30℃ compared with the design temperature. After the unit is kept running stably, it is tested for one hour as the second test condition. The main steam pressure, main steam temperature, regulating stage pressure, regulating stage temperature, reheat steam pressure, reheat steam temperature, intermediate pressure cylinder exhaust pressure, and intermediate pressure cylinder exhaust temperature are measured by the operating instruments (or test instruments) and then used for calculation.

[0056] Example 4

[0057] like Figure 2 As shown, the present invention provides a device for measuring steam leakage in the high- and intermediate-pressure combined cylinder of a reheat steam turbine, comprising:

[0058] The valve setting unit is used to set the opening of the steam inlet regulating valve of the intermediate pressure cylinder of the steam turbine to 100% and keep it unchanged, put the high pressure cylinder sequence valve into operation, keep the last valve of the high pressure inlet regulating valve closed, the remaining valves fully open, and the make-up steam valve fully closed, and keep it unchanged during the test.

[0059] The calculation unit is used to calculate two curves of the efficiency of the intermediate pressure cylinder as a function of the combined cylinder leakage under two test conditions with different steam parameters.

[0060] The intersection point acquisition unit is used to acquire the intersection point of the two curves showing the change of intermediate pressure cylinder efficiency with cylinder leakage, which is the actual cylinder shaft seal leakage.

[0061] In the valve setting unit of this embodiment, for a unit with four high-pressure steam inlet regulating valves, the test results of the turbine three-valve full-open test conducted simultaneously are used as test condition one; or for a unit with six high-pressure steam inlet regulating valves, the test results of the turbine five-valve full-open test conducted simultaneously are used as test condition one.

[0062] Calculation Example 1

[0063] This invention provides a method for determining the steam leakage of the high- and intermediate-pressure combined cylinder of a reheat steam turbine. Taking field test data from a power plant as an example, the calculation process is shown in the table below. The enthalpy of water vapor can be directly obtained from the property table using pressure and temperature, and the entropy can also be directly obtained from the property table using pressure and enthalpy.

[0064]

[0065]

[0066] Plot a straight line between the intermediate-pressure cylinder efficiency assuming 0% leakage at the intermediate-pressure cylinder junction and the intermediate-pressure cylinder efficiency assuming 8% leakage at the intermediate-pressure cylinder junction. Two straight lines can be obtained for the two test conditions. Plot these two lines on the same XY coordinate system, as shown below. Figure 1As shown. Since the efficiency of the intermediate-pressure cylinder remains constant in practice, the intersection of the two straight lines represents the actual efficiency of the intermediate-pressure cylinder, and the corresponding steam leakage at the intermediate-high pressure cylinder junction is the actual steam leakage.

[0067] This invention replaces the conventional "variable temperature method" with a "single variable method," which is simple; requires no additional instruments or equipment, resulting in low cost; obtains calculation results through the linear intersection method, a widely used method that ensures accuracy; can also be used with high- and medium-pressure combined-cylinder steam turbines that cannot meet the requirements of the "variable temperature method"; and only requires one steam temperature reduction test, mitigating the impact of special operating conditions on equipment lifespan. In summary, this invention has broad applicability and can be widely promoted and used.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0069] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for determining the steam leakage of the intermediate and high-pressure combined cylinder of a reheat steam turbine, characterized in that, include: 1) Set the opening of the steam inlet regulating valve of the intermediate pressure cylinder of the steam turbine to 100% and keep it unchanged. Put the high pressure cylinder sequence valve into operation, keep the last valve of the high pressure steam inlet regulating valve closed, the remaining valves fully open, and the make-up steam valve fully closed, and keep it unchanged during the test. 2) Through two test conditions with different steam parameters, two curves were obtained by calculation showing the change of intermediate pressure cylinder efficiency with cylinder leakage. 3) Obtain the intersection of the two curves showing the change in efficiency of the intermediate-pressure cylinder with the leakage of steam during cylinder connection. This intersection is the actual leakage of steam from the shaft seal during cylinder connection.

2. The method for determining the steam leakage of the intermediate and high-pressure combined cylinder of a reheat steam turbine according to claim 1, characterized in that, In step 1), for units with four high-pressure steam inlet valves, the test results of the turbine three-valve full-open test conducted concurrently are used as test condition one; or for units with six high-pressure steam inlet valves, the test results of the turbine five-valve full-open test conducted concurrently are used as test condition one.

3. The method for determining the steam leakage of the intermediate and high-pressure combined cylinder of a reheat steam turbine according to claim 2, characterized in that, In step 1), the boiler side flue gas parameters are adjusted by the operators or water is sprayed to reduce the reheat steam temperature by 20℃ to 30℃ compared with the design temperature, which is the second test condition.

4. A compressed air energy storage system for primary frequency regulation in a power plant according to claim 3, characterized in that, In step 2), the main steam pressure, main steam temperature, regulating stage pressure, regulating stage temperature, reheat steam pressure, reheat steam temperature, intermediate pressure cylinder exhaust pressure, and intermediate pressure cylinder exhaust temperature are obtained by testing. The enthalpy and entropy values ​​of the corresponding main steam, regulating stage steam, high pressure cylinder exhaust, reheat steam, and intermediate pressure cylinder exhaust are obtained by consulting the water and steam physical property parameter table.

5. A compressed air energy storage system for primary frequency regulation in a power plant according to claim 4, characterized in that, In step 2), assuming that the combined cylinder leakage rate accounts for 0% of the reheat steam flow rate, i.e. there is no combined cylinder leakage rate, the enthalpy of the intermediate pressure cylinder inlet steam is equal to the enthalpy of the reheat steam. Further calculate the intermediate pressure cylinder efficiency: intermediate pressure cylinder efficiency = (actual enthalpy drop at intermediate pressure cylinder inlet and outlet / isentropic enthalpy drop at intermediate pressure cylinder inlet and outlet) * 100%.

6. A compressed air energy storage system for primary frequency regulation in a power plant according to claim 5, characterized in that, In step 2), assuming that the leakage of steam in the combined cylinder accounts for 8% of the reheat steam flow, the enthalpy of the steam entering the intermediate pressure cylinder is calculated as (enthalpy of reheat steam + enthalpy of steam after regulating stage * 8%) / 108%. The efficiency of the intermediate pressure cylinder is then calculated as follows: intermediate pressure cylinder efficiency = (actual enthalpy drop at the inlet and outlet of intermediate pressure cylinder steam / isentropic enthalpy drop at the inlet and outlet of intermediate pressure cylinder steam) * 100%.

7. A compressed air energy storage system for primary frequency regulation in a power plant according to claim 6, characterized in that, For test condition one, after step 2), the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 0% of the reheat steam flow rate, and the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 8% of the reheat steam flow rate are obtained, thus obtaining a linear relationship between the intermediate-pressure cylinder efficiency and the combined cylinder leakage rate in test condition one; for test condition two, after step 2), the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 0% of the reheat steam flow rate, and the intermediate-pressure cylinder efficiency when the combined cylinder leakage rate accounts for 8% of the reheat steam flow rate are obtained, thus obtaining a linear relationship between the intermediate-pressure cylinder efficiency and the combined cylinder leakage rate in test condition two.

8. A compressed air energy storage system for primary frequency regulation in a power plant according to claim 7, characterized in that, In step 3), the linear relationship between the intermediate-pressure cylinder efficiency and the proportion of combined cylinder leakage in test conditions 1 and 2 is plotted on the same XY coordinate system, resulting in two intersecting straight lines. The intersection point corresponds to the actual intermediate-pressure cylinder efficiency and the actual proportion of combined cylinder leakage to the reheat steam flow.

9. A device for measuring steam leakage in the intermediate and high-pressure combined cylinder of a reheat steam turbine, characterized in that, include: The valve setting unit is used to set the opening of the steam inlet regulating valve of the intermediate pressure cylinder of the steam turbine to 100% and keep it unchanged, put the high pressure cylinder sequence valve into operation, keep the last valve of the high pressure inlet regulating valve closed, the remaining valves fully open, and the make-up steam valve fully closed, and keep it unchanged during the test. The calculation unit is used to calculate two curves of the efficiency of the intermediate pressure cylinder as a function of the combined cylinder leakage under two test conditions with different steam parameters. The intersection point acquisition unit is used to acquire the intersection point of the two curves showing the change of intermediate pressure cylinder efficiency with cylinder leakage, which is the actual cylinder shaft seal leakage.

10. The device for measuring steam leakage in the intermediate and high-pressure combined cylinder of a reheat steam turbine according to claim 9, characterized in that, In the valve setting unit, for units with four high-pressure steam inlet regulating valves, the test results of the turbine three-valve full-open test conducted simultaneously are used as test condition one; or for units with six high-pressure steam inlet regulating valves, the test results of the turbine five-valve full-open test conducted simultaneously are used as test condition one.

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