Steam turbine exhaust steam enthalpy calculation method and system

Abstract

The application provides a steam turbine exhaust enthalpy calculation method and system, and belongs to the technical field of steam turbines. The method comprises the following steps: calculating the actual low-pressure cylinder work amount according to the energy balance method; iteratively calculating the exhaust state parameters of the low-pressure cylinder of the steam turbine based on the operating parameters of the steam turbine; calculating the exhaust useful energy terminal enthalpy value of the low-pressure cylinder of the steam turbine and the assumed low-pressure cylinder work amount based on the exhaust state parameters of the low-pressure cylinder and the assumed low-pressure cylinder steam flow; comparing the actual low-pressure cylinder work amount with the assumed low-pressure cylinder work amount, and if the absolute value of the difference between the two is greater than a preset difference threshold, updating the assumed low-pressure cylinder steam flow and repeatedly performing the above steps until the preset difference threshold is met, and obtaining the latest assumed low-pressure cylinder steam flow; and outputting the exhaust useful energy terminal enthalpy value of the low-pressure cylinder of the steam turbine corresponding to the latest assumed low-pressure cylinder steam flow. The method has the characteristics of fewer required calculation parameters, fast iterative convergence and high precision, and ensures the calculation precision of the exhaust useful energy terminal enthalpy value of the low-pressure cylinder of the steam turbine.

Description

Technical Field

[0001] This invention relates to the field of steam turbine technology, and more specifically to a method for calculating the exhaust enthalpy of a steam turbine and a system for calculating the exhaust enthalpy of a steam turbine. Background Technology

[0002] With the global energy shortage and intensified market competition, energy conservation and consumption reduction have become the main objectives of thermal power plants. The low-pressure cylinder exhaust enthalpy of a steam turbine is a crucial parameter during turbine operation, significantly impacting the unit's economic performance. It is of great importance for performance monitoring and economic analysis of thermal power units.

[0003] The exhaust enthalpy of a steam turbine is divided into the useful energy endpoint enthalpy and the expansion line endpoint enthalpy. The useful energy endpoint enthalpy reflects the effective work done by steam within the low-pressure cylinder of the turbine, significantly impacting its performance and serving as a key parameter for economic analysis and determining optimal vacuum. The expansion line endpoint enthalpy, on the other hand, is the expansion endpoint enthalpy after deducting exhaust losses from the useful energy endpoint enthalpy, reflecting the theoretical efficiency determined by the expansion line of the flow path. Since the steam expands and performs work continuously within the low-pressure cylinder, its expansion line is smooth. Therefore, the expansion line endpoint enthalpy can be determined by extrapolating the expansion curve to the isobaric enthalpy-entropy line corresponding to the turbine exhaust pressure. However, determining the useful energy endpoint enthalpy requires determining the exhaust flow rate of the turbine's low-pressure cylinder. This necessitates measuring and calculating the flow rates of the entire inlet and outlet thermodynamic system. The required parameters are numerous, and measurement and calculation errors accumulate on the exhaust flow rate of the turbine's low-pressure cylinder, thus affecting the calculation of exhaust losses and consequently the accuracy of the calculation of the useful energy endpoint enthalpy of the turbine exhaust. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for calculating the exhaust enthalpy of a steam turbine, so as to at least solve the problem mentioned above that the large number of required parameters and the accumulation of measurement and calculation errors on the exhaust flow rate of the low-pressure cylinder of the steam turbine affect the calculation of exhaust loss, and thus affect the calculation accuracy of the useful energy endpoint enthalpy of the steam turbine exhaust.

[0005] To achieve the above objectives, a first aspect of the present invention provides a method for calculating the exhaust enthalpy of a steam turbine, comprising:

[0006] S110: Collect turbine operating parameters and calculate the actual work done by the low-pressure cylinder based on the energy balance method;

[0007] S120: Iterative calculation of exhaust state parameters of low-pressure cylinder of steam turbine based on turbine operating parameters;

[0008] S130: Calculate the useful energy endpoint enthalpy of the turbine's low-pressure cylinder exhaust based on the low-pressure cylinder exhaust state parameters and the assumed low-pressure cylinder inlet flow rate. Calculate the work done by the low-pressure cylinder based on the calculated useful energy endpoint enthalpy of the turbine's low-pressure cylinder exhaust and the assumed low-pressure cylinder inlet flow rate, and obtain the assumed work done by the low-pressure cylinder.

[0009] S140: Compare the actual low-pressure cylinder work with the assumed low-pressure cylinder work. If the absolute value of the difference between the two is greater than the preset difference threshold, update the assumed low-pressure cylinder steam flow rate and repeat S130 to S140 until the absolute value of the difference between the two is not greater than the preset difference threshold, and obtain the latest assumed low-pressure cylinder steam flow rate.

[0010] S150: Take the latest assumed low-pressure cylinder inlet steam flow rate corresponding to the turbine low-pressure cylinder exhaust useful energy endpoint enthalpy value as the actual useful energy endpoint enthalpy value, and output the actual useful energy endpoint enthalpy value.

[0011] Optionally, the above-mentioned exhaust state parameters of the turbine low-pressure cylinder include the enthalpy value at the end of the exhaust expansion line of the turbine low-pressure cylinder and the steam dryness at the end of the exhaust expansion line;

[0012] The aforementioned turbine operating parameters include at least the low-pressure cylinder exhaust pressure;

[0013] The above-mentioned calculation of the exhaust state parameters of the low-pressure cylinder of the steam turbine based on the iterative calculation of the steam turbine operating parameters includes:

[0014] A1: Pre-assuming the enthalpy H at the end of the exhaust expansion line of the low-pressure cylinder of the steam turbine. elep ;

[0015] A2: Based on the low-pressure cylinder exhaust pressure and the assumed H elep Calculate the entropy value S corresponding to the endpoint of the exhaust expansion line of the low-pressure cylinder of the steam turbine. elep ;

[0016] A3: The entropy value S elep Substituting into the expansion process line equation, the enthalpy H at the endpoint of the low-pressure cylinder exhaust expansion line of the steam turbine is calculated. i elep ;

[0017] A4: Calculate the hypothesis H elep With enthalpy H i elep If the error value does not meet the first preset error requirement, then H is re-assumed. elep And based on the re-hypothesized H elep Repeat steps A2 to A4 until the error value meets the first preset error requirement, and obtain the final enthalpy value H at the end of the exhaust expansion line of the low-pressure cylinder of the steam turbine. elep ;

[0018] A5: Based on the low-pressure cylinder exhaust pressure and the final enthalpy value H elep Calculate the steam dryness at the end of the exhaust expansion line.

[0019] Optionally, the steam extraction system of the above-mentioned steam turbine includes six-stage extraction, seven-stage extraction, and eight-stage extraction.

[0020] The above describes the entropy value S. elep Before substituting the expansion process line equation, the method also includes:

[0021] Based on the stage efficiency from the sixth stage extraction to the seventh stage extraction and the stage efficiency from the seventh stage extraction to the eighth stage extraction, calculate the enthalpy of the seventh stage extraction, the enthalpy of the eighth stage extraction, the entropy of the seventh stage extraction, and the entropy of the eighth stage extraction.

[0022] Based on the enthalpy values ​​of the seven-stage extraction steam, the enthalpy values ​​of the eight-stage extraction steam, the entropy values ​​of the seven-stage extraction steam, and the entropy values ​​of the eight-stage extraction steam, the expansion process line equation from the seventh stage extraction steam to the end point of the low-pressure cylinder exhaust steam of the turbine is fitted. Wherein, H8 is the enthalpy of the eight-stage extraction steam, H7 is the enthalpy of the seven-stage extraction steam, S8 is the entropy of the eight-stage extraction steam, and S7 is the entropy of the seven-stage extraction steam.

[0023] Optionally, the formula for calculating the enthalpy of the seven-stage extraction is H7 = H6 - η. 6-7 ×(H6-H s7 The formula for calculating the enthalpy of the eight-segment extraction steam is H8 = H7 - η / 100. 7-8 ×(H7-H s8 The formula for calculating the entropy of the seven-stage extraction steam is S7 = f / 100. S (P7,H7), the formula for calculating the entropy value of the eight-section steam extraction is S8=f S (P8,H8), where H6 is the enthalpy value of the six-stage extraction steam calculated based on the six-stage extraction steam pressure and temperature, H... s7 H is the isentropic enthalpy of the seven-stage extraction steam, calculated based on the entropy values ​​of the six-stage extraction steam and the pressure of the seven-stage extraction steam, and the entropy values ​​of the six-stage extraction steam are obtained based on the pressure and temperature of the six-stage extraction steam. s8 The isentropic enthalpy values ​​of the eight-stage extraction steam are calculated based on the entropy values ​​of the seven-stage extraction steam and the pressures of the eight-stage extraction steam. P7 represents the pressure of the seven-stage extraction steam, P8 represents the pressure of the eight-stage extraction steam, and η represents the isentropic enthalpy values ​​of the eight-stage extraction steam. 6-7 For the stage efficiency of six-stage extraction to seven-stage extraction, η 7-8 The efficiency ranges from seven-stage to eight-stage steam extraction.

[0024] Optionally, the actual work done by the low-pressure cylinder calculated using the energy balance method includes:

[0025] The first work quantity is calculated based on the steam flow rate and steam enthalpy of each stage from the main steam of the steam turbine to the high-pressure cylinder.

[0026] The second work quantity is calculated based on the steam flow rate and steam enthalpy of each stage of the reheat steam from the steam turbine to the intermediate pressure cylinder.

[0027] The actual low-pressure cylinder work is calculated based on the first and second work quantities.

[0028] Optionally, the steam extraction system of the above-mentioned steam turbine includes a first-stage steam extraction stage;

[0029] The above calculation of the first work quantity, based on the steam flow rate and steam enthalpy of each stage from the main steam of the steam turbine to the high-pressure cylinder, includes:

[0030] According to formula W z-t =M z-t ×(H z -H t ) / 3.6 Calculate the work done by the main steam from the turbine to the regulating stage of the turbine, where W z-t The work done by the main steam after it reaches the regulating stage, M z-t Steam flow rate after main steam reaches the regulating stage, H z The enthalpy of the main steam, H t The enthalpy of the steam after the regulating stage;

[0031] According to formula W t-1 =M t-1 ×(H t -H1) / 3.6 Calculate the work done by the turbine from the regulating stage to the first-stage extraction stage, where W t-1 To regulate the power output of the extraction stage, M t-1 To regulate the steam flow rate from the regulating stage to the first stage extraction steam, H t H1 is the steam enthalpy value after the regulating stage, and H1 is the steam enthalpy value of the first stage of steam extraction.

[0032] According to formula W 1-g =M 1-g ×(H1-H g ) / 3.6 Calculate the work done by the extraction of steam to the high-pressure cylinder exhaust, where W 1-g M represents the work done by the extraction of steam to the high-pressure cylinder for exhaust. 1-g H1 is the steam flow rate from the extraction stage to the high-pressure cylinder exhaust, and H1 is the steam enthalpy of the extraction stage. g This refers to the steam enthalpy value of the exhaust steam from the high-pressure cylinder.

[0033] According to formula W HP =W z-t +W t-1 +W 1-g The first work done is obtained, where W HP This represents the initial work done by steam in the high-pressure cylinder of the steam turbine.

[0034] Optionally, the steam extraction system of the above-mentioned steam turbine includes three-stage steam extraction;

[0035] The second work quantity is calculated based on the steam flow rate and enthalpy of the reheat steam from the turbine to each stage in the intermediate-pressure cylinder, including:

[0036] According to formula W zr-3 =M zr-3 ×(H zr -H3) / 3.6 yields the work done by the reheated steam to the third-stage extraction, where W zr-3 M represents the work done by the reheated steam to the third stage extraction steam. zr-3 H is the steam flow rate from reheat steam to the third stage extraction steam. zr H3 is the steam enthalpy of the reheat steam, and H4 is the steam enthalpy of the three-stage extraction steam.

[0037] According to formula W 3-ip =M 3-ip ×(H3-H ip The work done by the three-stage extraction of steam to the intermediate-pressure cylinder exhaust is obtained from W / 3.6. 3-ip M represents the work done by the three-stage extraction of steam to the intermediate-pressure cylinder exhaust. 3-ip H represents the steam flow rate from the three-stage extraction steam to the intermediate-pressure cylinder exhaust. ip This refers to the steam enthalpy value of the exhaust steam from the intermediate-pressure cylinder.

[0038] According to formula W IP =W zr-3 +W 3-ip The work done by the intermediate pressure cylinder is obtained, where W IP This is the second amount of work done by steam in the intermediate pressure cylinder of the steam turbine.

[0039] Optionally, the calculation formula for the actual low-pressure cylinder work based on the first and second work quantities is as follows:

[0040] W LP =W e / (η m ·η e ·10 -4 )-W HP -W IP Among them, W LP W represents the actual work done by the low-pressure cylinder. e η is the power of the steam turbine generator set. m For mechanical efficiency, η e For generator efficiency, W HP For the first amount of work done, W IP This is the second amount of work done.

[0041] Optionally, the above calculation of the useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust based on the low-pressure cylinder exhaust state parameters and the assumed low-pressure cylinder inlet steam flow includes:

[0042] Pre-assuming low-pressure cylinder inlet steam flow rate M LP ;

[0043] Based on the assumption that the low-pressure cylinder inlet steam flow rate M LP Calculate the useful energy endpoint enthalpy of the exhaust steam from the turbine's low-pressure cylinder by taking the steam dryness at the endpoint of the exhaust expansion line and the enthalpy at the endpoint of the exhaust expansion line.

[0044] Optionally, the above assumes a low-pressure cylinder inlet steam flow rate M. LP The calculation includes the steam dryness fraction at the end of the exhaust expansion line and the enthalpy value at the end of the exhaust expansion line of the turbine low-pressure cylinder, as well as the useful energy endpoint enthalpy value of the turbine low-pressure cylinder exhaust, including:

[0045] Based on the assumption that the low-pressure cylinder inlet steam flow rate M LP The exhaust loss EL of the last stage of the low-pressure cylinder is calculated.

[0046] According to formula H ueep =H elep -0.87×X×EL yields the endpoint enthalpy of useful energy from the exhaust steam of the low-pressure cylinder of the steam turbine, where H ueep H represents the useful energy endpoint enthalpy of exhaust steam from the low-pressure cylinder of the steam turbine. elep X represents the enthalpy value at the end of the exhaust expansion line of the low-pressure cylinder of the steam turbine, X represents the steam dryness at the end of the exhaust expansion line, and EL represents the exhaust loss of the last stage of the low-pressure cylinder.

[0047] Optionally, the steam extraction system of the above-mentioned steam turbine includes five-stage extraction, six-stage extraction, seven-stage extraction and eight-stage extraction;

[0048] The above is based on the assumption that the low-pressure cylinder inlet steam flow rate M LP The calculated exhaust loss EL of the last stage of the low-pressure cylinder includes:

[0049] Calculate the steam extraction flow rates for the fifth, sixth, seventh, and eighth stages respectively.

[0050] According to formula M e =M LP -M5-M6-M7-M8+M LPz Calculate the low-pressure cylinder exhaust flow rate, where M e M is the exhaust flow rate of the low-pressure cylinder of the steam turbine. LPz M5 is the steam inlet flow rate for the low-pressure cylinder shaft seal, M6 is the steam extraction flow rate for five stages, M7 is the steam extraction flow rate for six stages, M8 is the steam extraction flow rate for seven stages, and M8 is the steam extraction flow rate for eight stages.

[0051] Calculate the specific volume V of the low-pressure cylinder exhaust based on the low-pressure cylinder exhaust pressure and the enthalpy at the end of the low-pressure cylinder exhaust expansion line. e ;

[0052] According to formula Q e =M e / V e The volumetric flow rate Q of the low-pressure cylinder exhaust is obtained. e ;

[0053] The volumetric flow rate Q of the low-pressure cylinder exhaust e Inputting the data into a preset relationship table, the low-pressure cylinder final stage exhaust loss EL is obtained through matching. The preset relationship table includes Q. e The correspondence between EL and EL.

[0054] Optionally, the formulas for calculating the steam flow rates of the five-stage, six-stage, seven-stage, and eight-stage extraction stages are as follows: Among them, M n For condensate flow rate, H 5c The enthalpy of the outlet water at No. 5 is H. 5j H5 is the enthalpy of the inlet water at the No. 5 low-pressure heater, and H5 is the enthalpy of the extraction steam at the fifth stage. 5s The enthalpy of hydrophobicity is H, which is the value of the No. 5 low-pressure hydrophobic 6c The enthalpy of the outlet water at No. 6 low pressure, H 6j H6 is the enthalpy of the inlet water at the No. 6 low-pressure heater, and H6 is the enthalpy of the extraction steam at the sixth stage. 6s The enthalpy of hydrophobicity of No. 6 is H. 7c The enthalpy of the water discharged from the No. 7 low-pressure heater is H. 7j H7 is the enthalpy of the inlet water at the No. 7 low-pressure heater, and H7 is the enthalpy of the extraction steam at the seventh stage. 7s The enthalpy of hydrophobicity of No. 7 is H. 8c The enthalpy of the water discharged from the No. 8 low-pressure heater, H 8j H8 is the enthalpy of the inlet water at the No. 8 low-pressure heater, and H8 is the enthalpy of the steam extraction at the eighth stage. 8s The enthalpy value is the hydrophobic value of No. 8.

[0055] Optionally, the above calculation of the work done by the low-pressure cylinder based on the calculated useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust and the assumed low-pressure cylinder inlet steam flow rate, to obtain the assumed low-pressure cylinder work, includes:

[0056] According to formula W L-5 =M LP ×(H LP -H5) / 3.6 Calculate the work done from the low-pressure cylinder steam intake to the fifth stage steam extraction;

[0057] According to formula W 5-6 =(M LP -M5)×(H5-H6) / 3.6 Calculate the work done from the fifth stage extraction to the sixth stage extraction;

[0058] According to formula W 6-7 =(M LP -M5-M6)×(H6-H7) / 3.6 Calculate the work done from the sixth stage extraction to the seventh stage extraction;

[0059] According to formula W 7-8 =(M LP -M5-M6-M7)×(H7-H8) / 3.6 Calculate the work done from the seventh stage extraction to the eighth stage extraction;

[0060] According to formula W 8-ueep =(M LP -M5-M6-M7-M8)×(H8-H ueep ) / 3.6 Calculate the work done by the eight-stage extraction steam to the low-pressure cylinder exhaust;

[0061] According to formula W LP =W L-5 +W 5-6 +W 6-7 +W 7-8 +W 8-ueep Calculate the work done by the low-pressure cylinder to obtain the assumed work done by the low-pressure cylinder, where M LP Assuming the low-pressure cylinder inlet steam flow rate, M 5-6 M represents the steam flow rate from the fifth stage extraction to the sixth stage extraction. 6-7 M represents the steam flow rate from the sixth stage extraction to the seventh stage extraction. 7-8 M represents the steam flow rate from the seventh to the eighth stage of extraction. 8-ueep W represents the steam flow rate from the eight-stage extraction steam to the low-pressure cylinder exhaust. L-5 W is the work done from the low-pressure cylinder intake to the fifth stage extraction. 5-6 W represents the work done by steam extraction from stage five to stage six. 6-7 W represents the work done by steam extraction from stage six to stage seven. 7-8 W represents the work done from the seventh to the eighth stage of steam extraction. 8-ueep H represents the work done by the eight-stage extraction of steam to the low-pressure cylinder exhaust. LP H represents the enthalpy of steam entering the low-pressure cylinder. ueep W represents the useful energy endpoint enthalpy of the low-pressure cylinder exhaust. LP H5 represents the assumed work done by steam in the low-pressure cylinder of the turbine, H6 represents the enthalpy of the fifth extraction stage, H7 represents the enthalpy of the sixth extraction stage, and H8 represents the enthalpy of the seventh extraction stage.

[0062] A second aspect of the present invention provides a turbine exhaust enthalpy calculation system, comprising:

[0063] The actual low-pressure cylinder work calculation module is used to collect turbine operating parameters and calculate the actual low-pressure cylinder work based on the energy balance method.

[0064] The low-pressure cylinder exhaust state parameter iterative calculation module is used to iteratively calculate the exhaust state parameters of the turbine's low-pressure cylinder based on the turbine's operating parameters.

[0065] The assumed low-pressure cylinder work calculation module is used to calculate the useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust based on the low-pressure cylinder exhaust state parameters and the assumed low-pressure cylinder inlet flow rate. Based on the calculated useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust and the assumed low-pressure cylinder inlet flow rate, the low-pressure cylinder work is calculated to obtain the assumed low-pressure cylinder work.

[0066] The repeated execution module is used to compare the actual low-pressure cylinder work and the assumed low-pressure cylinder work. If the absolute value of the difference between the two is greater than the preset difference threshold, the assumed low-pressure cylinder inlet steam flow rate is updated and the assumed low-pressure cylinder work calculation module is repeatedly executed until the absolute value of the difference between the two is no greater than the preset difference threshold, and the latest assumed low-pressure cylinder inlet steam flow rate is obtained.

[0067] The actual useful energy endpoint enthalpy output module is used to take the latest assumed low-pressure cylinder inlet steam flow rate corresponding to the turbine low-pressure cylinder exhaust useful energy endpoint enthalpy value as the actual useful energy endpoint enthalpy value and output the actual useful energy endpoint enthalpy value.

[0068] In a third aspect, the present invention provides a machine-readable storage medium storing instructions that, when executed by a processor, configure the processor to perform the aforementioned method for calculating the exhaust enthalpy of a steam turbine.

[0069] In a fourth aspect, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the aforementioned method for calculating the exhaust enthalpy of steam turbines.

[0070] Through the above technical solution, a method and system for calculating the exhaust enthalpy of a steam turbine calculates the actual work done by the low-pressure cylinder based on the energy balance method. After iteratively calculating the exhaust state parameters of the low-pressure cylinder according to the turbine operating parameters, the assumed low-pressure cylinder exhaust useful energy endpoint enthalpy and the work done by the steam in the low-pressure cylinder are calculated based on the assumed low-pressure cylinder inlet steam flow rate and the exhaust state parameters. The assumed low-pressure cylinder work is then obtained by comparing the actual low-pressure cylinder work with the assumed low-pressure cylinder work. If the absolute value of the difference between the two is greater than a preset difference threshold, the assumed low-pressure cylinder inlet steam flow rate is updated, and the useful energy endpoint enthalpy of the exhaust steam in the low-pressure cylinder is iteratively calculated. After the iterative calculation is completed, the actual useful energy endpoint enthalpy is obtained. Furthermore, by combining the energy balance method with the work done by the low-pressure cylinder of the steam turbine as the benchmark, the steam inlet flow rate of the low-pressure cylinder is calculated iteratively. This avoids the influence of measurement errors caused by measuring the steam inlet flow rate of the feedwater pump turbine, the flow rate of the auxiliary steam header, and the flow rate of the intermediate exhaust heating steam, thereby ensuring the accuracy of the calculation of the useful energy endpoint enthalpy value of the steam turbine low-pressure cylinder exhaust. This method and system have the characteristics of requiring few calculation parameters, fast iteration convergence, and high accuracy. They can be applied to online monitoring of the efficiency of the steam turbine low-pressure cylinder and online economic analysis. For field personnel, this method and system can also be used to quickly estimate the exhaust enthalpy of the low-pressure cylinder based on the work done by the low-pressure cylinder, demonstrating good application value.

[0071] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0072] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0073] Figure 1 This is a flowchart of a method for calculating the exhaust enthalpy of a steam turbine, provided by one embodiment of the present invention;

[0074] Figure 2 This is a schematic diagram of the iterative calculation process for the endpoint enthalpy of the exhaust expansion line of a steam turbine low-pressure cylinder provided in one embodiment of the present invention;

[0075] Figure 3 This is a schematic diagram of the iterative calculation process for the useful energy endpoint enthalpy of exhaust steam from a low-pressure cylinder of a steam turbine, provided by one embodiment of the present invention.

[0076] Figure 4 This is a schematic diagram of a thermal system provided in one embodiment of the present invention;

[0077] Figure 5 This is a block diagram of a steam turbine exhaust enthalpy calculation system provided in one embodiment of the present invention;

[0078] Figure 6 This is a schematic diagram of an electronic device structure provided by a preferred embodiment of the present invention.

[0079] Explanation of reference numerals in the attached figures

[0080] 1-Boiler, 2-Reheat steam pipe, 3-Main steam pipe, 4-Intermediate and low-pressure cylinder connecting pipe, 5-High-pressure cylinder, 6-Intermediate-pressure cylinder, 7-Low-pressure cylinder, 8-Generator, 9-High-pressure exhaust pipe, 10-Electronic equipment, 100-Processor, 101-Memory, 102-Computer program, 11-First stage extraction steam, 12-Fourth stage extraction steam, 13-Low-pressure cylinder exhaust pipe, 14-Feed water pump, 15-Deaerator, 16-Condenser, 17-Condenser Pump, 18-Water supply pipe, 19-Second stage steam extraction, 20-Third stage steam extraction, 21-Fifth stage steam extraction, 22-Sixth stage steam extraction, 23-Seventh stage steam extraction, 24-Eighth stage steam extraction, 25-No. 5 low-pressure heater, 26-No. 6 low-pressure heater, 27-No. 7 low-pressure heater, 28-No. 8 low-pressure heater, 29-No. 2 high-pressure heater, 30-No. 3 high-pressure heater, 31-Condensate pipe, 32-High-pressure heater drain pipe, 33-Low-pressure heater drain pipe, 34-Regulating stage, 35-No. 1 high-pressure heater. Detailed Implementation

[0081] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0082] Figure 4 This is a schematic diagram of a thermal system provided in one embodiment of the present invention. Figure 4 As shown, the thermal system of a thermal power plant includes a boiler 1, reheat steam pipeline 2, main steam pipeline 3, intermediate and low-pressure cylinder connecting pipe 4, high-pressure cylinder 5, intermediate-pressure cylinder 6, low-pressure cylinder 7, generator 8, high-pressure exhaust pipeline 9, regulating stage 34, first-stage extraction steam 11, fourth-stage extraction steam 12, low-pressure cylinder exhaust pipeline 13, feedwater pump 14, deaerator 15, condenser 16, condensate pump 17, feedwater pipeline 18, second-stage extraction steam 19, third-stage extraction steam 20, fifth-stage extraction steam 21, sixth-stage extraction steam 22, seventh-stage extraction steam 23, eighth-stage extraction steam 24, No. 5 low-pressure heater 25, No. 6 low-pressure heater 26, No. 7 low-pressure heater 27, No. 8 low-pressure heater 28, No. 1 high-pressure heater 35, No. 2 high-pressure heater 29, No. 3 high-pressure heater 30, condensate pipeline 31, high-pressure heater drain pipeline 32, and low-pressure heater drain pipeline 33. The main steam pipe 3 of the turbine's main steam is connected to the regulating stage 34, which is located on the high-pressure cylinder 5. The high-pressure cylinder 5 has a section of extraction steam 11. The reheat steam pipe 2 of the turbine's reheat steam is connected to the No. 3 high-pressure heater 30, which has three sections of extraction steam 20 and is connected to the intermediate-pressure cylinder 6.

[0083] Figure 1This is a flowchart illustrating a method for calculating the exhaust enthalpy of a steam turbine, provided by one embodiment of the present invention. Figure 1 As shown, an embodiment of the present invention provides a method for calculating the exhaust enthalpy of a steam turbine, comprising:

[0084] S110: Collect turbine operating parameters and calculate the actual work done by low-pressure cylinder 7 based on the energy balance method;

[0085] It should be noted that the above-mentioned energy balance method, also known as the enthalpy balance method or energy balance method, is an analytical method based on the first law of thermodynamics. It uses the principle of energy balance and thermodynamic efficiency as the criterion to calculate the total energy entering the system, determine the energy discharged by the system and the energy utilization rate, and thereby determine the system's heat loss, theoretical heat load, recoverable waste heat, and other results.

[0086] In some embodiments of this example, the calculation of the actual work done by the low-pressure cylinder 7 based on the energy balance method includes:

[0087] The first work is calculated based on the steam flow rate and enthalpy of each stage in the high-pressure cylinder 5 from the main steam of the turbine; the second work is calculated based on the steam flow rate and enthalpy of each stage in the intermediate-pressure cylinder 6 from the reheat steam of the turbine; and the actual work of the low-pressure cylinder 7 is calculated based on the first and second work. The stages in the high-pressure cylinder 5 from the main steam of the turbine include the main steam from the turbine to the regulating stage 34, the regulating stage 34 to the first extraction stage 11, and the first extraction stage 11 to the exhaust steam from the high-pressure cylinder 5. The stages in the intermediate-pressure cylinder 6 from the turbine include the reheat steam to the third extraction stage 20 and the third extraction stage 20 to the exhaust steam from the intermediate-pressure cylinder 6.

[0088] The steam extraction system of the aforementioned steam turbine includes a first extraction stage 11. The first work output is calculated based on the steam flow rate and enthalpy of each stage from the main steam of the steam turbine to the high-pressure cylinder 5, including:

[0089] According to formula W z-t =M z-t ×(H z -H t ) / 3.6 Calculate the work done by the main steam from the turbine to the regulating stage 34 of the turbine, where W z-t The work done by the main steam after reaching the regulating stage 34, M z-t Steam flow rate (H) after main steam reaches regulating stage 34 z The enthalpy of the main steam, H t The steam enthalpy value after regulating stage 34;

[0090] According to formula W t-1 =M t-1 ×(Ht -H1) / 3.6 Calculate the work done by the regulating stage 34 to the first extraction stage 11 of the steam turbine, where W t-1 For the power output of regulating stage 34 to first-stage extraction stage 11, M t-1 For the steam flow rate from regulating stage 34 to the first extraction stage 11, H t H1 is the steam enthalpy value after regulating stage 34, and H1 is the steam enthalpy value of extraction stage 11.

[0091] According to formula W 1-g =M 1-g ×(H1-H g ) / 3.6 Calculate the work done by the extraction steam from section 11 to the exhaust steam from section 5 of the high-pressure cylinder, where W 1-g M represents the work done by the extraction steam from cylinder 11 to the exhaust steam from cylinder 5 of high-pressure cylinder. 1-g H1 is the steam flow rate from extraction steam 11 to high-pressure cylinder 5, and H1 is the steam enthalpy of extraction steam 11. g This is the steam enthalpy value of the exhaust steam from the high-pressure cylinder 5;

[0092] According to formula W HP =W z-t +W t-1 +W 1-g The first work done is obtained, where W HP This represents the first amount of work done by steam in the high-pressure cylinder 5 of the steam turbine.

[0093] Furthermore, the aforementioned steam turbine extraction system includes a three-stage extraction system 20. The second work output is calculated based on the steam flow rate and enthalpy of each stage in the intermediate-pressure cylinder 6 from the reheat steam of the steam turbine, including:

[0094] According to formula W zr-3 =M zr-3 ×(H zr -H3) / 3.6 yields the work done by reheating steam to the third-stage extraction steam 20, where W zr-3 M is the work done by reheating steam to the third stage extraction steam 20. zr-3 For reheat steam to the steam flow rate of the third-stage extraction steam 20, H zr H3 is the steam enthalpy of reheat steam, and H3 is the steam enthalpy of three-stage extraction steam 20.

[0095] According to formula W 3-ip =M 3-ip ×(H3-H ip The work done by the three-stage extraction steam (20) to the exhaust steam of the intermediate-pressure cylinder (6) is obtained from W / 3.6. 3-ip M represents the power output of the exhaust steam from the third stage extraction cylinder (20 tons) to the intermediate pressure cylinder (6 tons). 3-ip H represents the steam flow rate from the third-stage extraction steam 20 to the exhaust steam from the intermediate-pressure cylinder 6. ip The steam enthalpy of the exhaust steam from the intermediate-pressure cylinder 6;

[0096] According to formula W IP =W zr-3 +W 3-ip The work done by the intermediate pressure cylinder 6 is obtained, of which W IP This is the second amount of work done by steam in the intermediate pressure cylinder 6 of the steam turbine.

[0097] It should be noted that the steam flow rate, steam enthalpy of each stage, steam enthalpy of exhaust from high-pressure cylinder 5, and steam enthalpy of exhaust from intermediate-pressure cylinder 6 used in the formulas for calculating the first and second work can all be obtained by collecting pressure, temperature, and flow rate data from the power plant's DCS system and calculating them using conventional thermodynamic performance calculation methods based on the collected pressure, temperature, and flow rate data. This is a conventional technique and will not be elaborated upon here.

[0098] The calculation formula for the actual work done by the low-pressure cylinder 7, based on the first and second work done, is as follows: W LP =W e / (η m ·η e ·10 -4 )-W HP -W IP Among them, W LP For the actual work done by low-pressure cylinder 7, W e For the power of 8 steam turbine generator sets, η m For mechanical efficiency, η e For generator efficiency 8, W HP For the first amount of work done, W IP This is the second amount of work done.

[0099] S120: Iterative calculation of exhaust state parameters of low-pressure cylinder 7 of steam turbine based on turbine operating parameters;

[0100] Please refer to Figure 2 , Figure 2 This is a schematic diagram of the iterative calculation process for the enthalpy at the endpoint of the exhaust expansion line of the low-pressure cylinder 7 of a steam turbine, provided in one embodiment of the present invention. In some embodiments of this invention, the exhaust state parameters of the low-pressure cylinder 7 of the steam turbine include the enthalpy value at the endpoint of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine and the steam dryness at the endpoint of the exhaust expansion line; the steam turbine operating parameters include at least the exhaust pressure of the low-pressure cylinder 7; the iterative calculation of the exhaust state parameters of the low-pressure cylinder 7 of the steam turbine based on the steam turbine operating parameters includes:

[0101] A1: Pre-assuming the enthalpy H at the end of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine. elep ;

[0102] A2: Based on the exhaust pressure of low-pressure cylinder 7 and the assumed H elepCalculate the entropy value S corresponding to the endpoint of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine. elep ;

[0103] Specifically, using water and steam property calculation software based on the exhaust pressure of low-pressure cylinder 7 and assumed H... elep Calculate the entropy value S corresponding to the endpoint of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine. elep .

[0104] A3: The entropy value S elep Substituting into the expansion process line equation, the enthalpy H at the endpoint of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine is calculated. i elep ;

[0105] In some embodiments of this example, the steam extraction system of the steam turbine includes a six-stage extraction 22, a seven-stage extraction 23, and an eight-stage extraction 24. The entropy value S is described above. elep Before substituting the expansion process line equation, the method also includes:

[0106] Based on the stage efficiency of extraction steam from stage 6 to stage 7 and extraction steam from stage 7 to stage 8, calculate the enthalpy of extraction steam from stage 7 to stage 8, the enthalpy of extraction steam from stage 7 to stage 8, the entropy of extraction steam from stage 7 to stage 8, and the entropy of extraction steam from stage 7 to stage 8.

[0107] The formula for calculating the enthalpy of the seven-stage extraction steam is H7 = H6 - η. 6-7 ×(H6-H s7 The formula for calculating the enthalpy of steam extraction in the eight sections is H8 = H7 - η / 100. 7-8 ×(H7-H s8 The formula for calculating the entropy value of the seventh stage steam extraction 23 is S7 = f / 100. S (P7,H7), the formula for calculating the entropy value of the eight-section steam extraction 24 is S8=f S (P8,H8), where H6 is the enthalpy value of the sixth-stage extraction steam 22 calculated based on the pressure and temperature of the sixth-stage extraction steam 22, and H... s7 The isentropic enthalpy of the seventh-stage extraction steam 23 is calculated based on the entropy value of the sixth-stage extraction steam 22 and the pressure of the seventh-stage extraction steam 23, and the entropy value of the sixth-stage extraction steam 22 is obtained based on the pressure and temperature of the sixth-stage extraction steam 22. s8 The isentropic enthalpy of the eighth-stage extraction steam 24 is calculated based on the entropy value of the seventh-stage extraction steam 23 and the pressure of the eighth-stage extraction steam 24. P7 represents the pressure of the seventh-stage extraction steam 23, P8 represents the pressure of the eighth-stage extraction steam 24, and η represents the pressure of the eighth-stage extraction steam 24. 6-7 For the stage efficiency of the sixth stage extraction steam 22 to the seventh stage extraction steam 23, η 7-8 The efficiency is calculated for stages 7-stage extraction steam 23 to 8-stage extraction steam 24. The enthalpy H6 of stage 6 extraction steam 22 is calculated using software based on the pressure and temperature of stage 6 extraction steam 22 and the properties of water and steam. The isentropic enthalpy H of stage 7 extraction steam 23 is...s7 The entropy (H) of the sixth-stage extraction steam 22 is calculated using software based on the properties of water and steam, taking into account the entropy of the sixth-stage extraction steam 22 and the pressure of the seventh-stage extraction steam 23. The entropy of the sixth-stage extraction steam 22 can be calculated using the same software based on its pressure and temperature, taking into account the properties of water and steam. The isentropic enthalpy (H) of the eighth-stage extraction steam 24 is... s8 It is calculated using software based on the entropy of the seventh-stage extraction steam 23 and the pressure of the eighth-stage extraction steam 24, taking into account the properties of water and steam. The entropy of the seventh-stage extraction steam 23 can be calculated using software based on the pressure and enthalpy of the seventh-stage extraction steam 23, taking into account the properties of water and steam.

[0108] Based on the enthalpy values ​​of the seventh-stage extraction steam 23, the eighth-stage extraction steam 24, the entropy values ​​of the seventh-stage extraction steam 23 and the eighth-stage extraction steam 24, the expansion process line equation from the seventh-stage extraction steam 23 to the exhaust endpoint of the low-pressure cylinder 7 of the steam turbine is fitted. Wherein, H8 is the enthalpy value of the eight-stage extraction steam at 24, H7 is the enthalpy value of the seven-stage extraction steam at 23, S8 is the entropy value of the eight-stage extraction steam at 24, and S7 is the entropy value of the seven-stage extraction steam at 23.

[0109] A4: Calculate the hypothesis H elep With enthalpy H i elep If the error value does not meet the first preset error requirement, then H is re-assumed. elep And based on the re-hypothesized H elep Repeat steps A2 to A4 until the error value meets the first preset error requirement, and obtain the final enthalpy value H at the end of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine. elep ;

[0110] Specifically, if we assume H elep With enthalpy H i elep Error value |H i elep -H elep If | is less than ε1, then output H elep Conversely, if |H i elep -H elep If the value is not less than ε1, then re-assume H. elep And repeat steps A2 through A4 until the error value |H is reached. i elep -H elep If the value is less than ε1, the iterative calculation stops. After the iterative calculation is completed, the final enthalpy value H at the end of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine is obtained. elep .

[0111] A5: Based on the exhaust pressure of low-pressure cylinder 7 and the final enthalpy value H elep Calculate the steam dryness at the end of the exhaust expansion line.

[0112] Specifically, the calculation software for the properties of water and water vapor is used based on the exhaust pressure of the low-pressure cylinder 7 and the final enthalpy value H. elep Calculate the steam dryness at the end of the exhaust expansion line.

[0113] S130: Calculate the useful energy endpoint enthalpy of the exhaust of the turbine's low-pressure cylinder 7 based on the exhaust state parameters of the low-pressure cylinder 7 and the assumed steam inlet flow rate of the low-pressure cylinder 7. Calculate the work done by the low-pressure cylinder 7 based on the calculated useful energy endpoint enthalpy of the turbine's low-pressure cylinder 7 and the assumed steam inlet flow rate of the low-pressure cylinder 7, and obtain the assumed work done by the low-pressure cylinder 7.

[0114] Please refer to Figure 3 , Figure 3 This is a schematic diagram of the iterative calculation process for the useful energy endpoint enthalpy of the exhaust steam from the low-pressure cylinder 7 of a steam turbine, provided in one embodiment of the present invention. In some embodiments of this invention, the above-mentioned calculation of the useful energy endpoint enthalpy of the exhaust steam from the low-pressure cylinder 7 of the steam turbine based on the exhaust state parameters of the low-pressure cylinder 7 and the assumed steam inlet flow rate of the low-pressure cylinder 7 includes: pre-assuming the steam inlet flow rate M of the low-pressure cylinder 7. LP Based on the assumption that the steam flow rate M in the low-pressure cylinder 7 is... LP Calculate the useful energy endpoint enthalpy of the exhaust steam at the endpoint of the exhaust expansion line and the enthalpy value at the endpoint of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine.

[0115] Among them, the above is based on the assumption that the steam flow rate M of the low-pressure cylinder 7 is... LP The steam dryness fraction at the end of the exhaust expansion line and the enthalpy value at the end of the exhaust expansion line of the turbine low-pressure cylinder 7 are used to calculate the useful energy enthalpy value at the end of the exhaust of the turbine low-pressure cylinder 7, including:

[0116] Based on the assumption that the steam inlet flow rate M of the low-pressure cylinder 7 LP The exhaust loss EL of the last stage of the low-pressure cylinder 7 was calculated.

[0117] The steam extraction system of the aforementioned steam turbine includes five-stage extraction (21), six-stage extraction (22), seven-stage extraction (23), and eight-stage extraction (24). The above is based on the assumption that the steam inlet flow rate M of the low-pressure cylinder 7 is... LP The final stage exhaust loss EL of the low-pressure cylinder 7 was calculated, including: calculating the flow rates of the fifth-stage extraction steam 21, the sixth-stage extraction steam 22, the seventh-stage extraction steam 23, and the eighth-stage extraction steam 24 respectively; according to formula M e =M LP -M5-M6-M7-M8+M LPz Calculate the exhaust steam flow rate of low-pressure cylinder 7, where M e M is the exhaust steam flow rate of the low-pressure cylinder 7 of the steam turbine. LPzM5 represents the steam inlet flow rate for the shaft seal of low-pressure cylinder 7; M6 represents the flow rate for the fifth-stage extraction steam (21); M7 represents the flow rate for the sixth-stage extraction steam (22); M8 represents the flow rate for the seventh-stage extraction steam (23); and M9 represents the flow rate for the eighth-stage extraction steam (24). Based on the exhaust pressure of low-pressure cylinder 7 and the enthalpy value at the endpoint of the exhaust expansion line of low-pressure cylinder 7, calculate the specific volume V of the exhaust steam of low-pressure cylinder 7. e According to formula Q e =M e / V e The volumetric flow rate Q of the exhaust steam from low-pressure cylinder 7 is obtained. e The volumetric flow rate Q of the exhaust steam from low-pressure cylinder 7 e Inputting the data into the preset relationship table, the final stage exhaust loss EL of the low-pressure cylinder 7 is obtained. The preset relationship table includes Q. e The correspondence between EL and EL. Specifically, when calculating the exhaust loss EL, firstly, based on the assumed inlet steam flow rate of low-pressure cylinder 7, the exhaust steam flow rate of low-pressure cylinder 7 is calculated. Then, based on the exhaust pressure of low-pressure cylinder 7 and the enthalpy at the end of the expansion line, the specific volume V of the exhaust steam of low-pressure cylinder 7 is calculated using water and steam property calculation software. e The volumetric flow rate Q of the exhaust steam from low-pressure cylinder 7 was calculated. e =M e / V e Finally, the exhaust loss EL is obtained by referring to the relationship curve between exhaust loss and exhaust volumetric flow rate of low-pressure cylinder 7 provided by the turbine manufacturer, or by fitting the exhaust loss curve relationship formula and directly calculating the exhaust loss EL based on the exhaust volumetric flow rate of low-pressure cylinder 7. Both the relationship curve lookup and the exhaust loss curve relationship formula belong to the aforementioned preset relationship table.

[0118] In some embodiments of this example, the formulas for calculating the flow rates of the fifth-stage extraction steam 21, the sixth-stage extraction steam 22, the seventh-stage extraction steam 23, and the eighth-stage extraction steam 24 are as follows: Among them, M n For condensate flow rate, H 5c The enthalpy value of the outlet water at No. 5 low heater 25, H 5j H5 is the enthalpy of the No. 5 low-pressure heater with a feed water enthalpy of 25, and H5 is the enthalpy of the fifth-stage extraction steam with a feed water enthalpy of 21. 5s The enthalpy of hydrophobicity is 25°C for No. 5 low-pressure heater, H. 6c The enthalpy of the outlet water from heater #6 is H. 6j H6 is the enthalpy of the 26-point inlet water for the No. 6 low-pressure heater, and H6 is the enthalpy of the 22-point extraction steam for the sixth stage. 6s The enthalpy of hydrophobicity of the No. 6 low-pressure heater is H. 7c The enthalpy of the water outlet at No. 7 low heater 27, H 7j H7 is the enthalpy of the 27-point inlet water for the No. 7 low-pressure heater, and H7 is the enthalpy of the 23-point extraction steam for the seventh stage. 7s The hydrophobic enthalpy of the No. 7 low-pressure heater is 27, H. 8c The enthalpy of the water outlet from heater #8 is 28, H. 8jH8 is the enthalpy of the 28-point inlet water for the No. 8 low-pressure heater, and H8 is the enthalpy of the 24-point extraction steam for the eighth stage. 8s H5 is the enthalpy of the hydrophobic material at the No. 8 low-pressure heater 28. Furthermore, H5 is the enthalpy of the steam extraction at the fifth stage 21, calculated based on the pressure and temperature.

[0119] It should be noted that the inlet enthalpy, outlet enthalpy, condensate enthalpy, steam inlet enthalpy, and condensate flow rate of each low-pressure heater required for calculating the steam extraction flow rate of each section can all be obtained by collecting the pressure, temperature, and flow rate of the power plant's DCS system and calculating them using water and steam property calculation software. This is a conventional technique and will not be elaborated upon here.

[0120] According to formula H ueep =H elep -0.87×X×EL yields the useful energy endpoint enthalpy of the exhaust steam from the low-pressure cylinder 7 of the steam turbine, where H ueep H represents the useful energy endpoint enthalpy of the exhaust steam from the low-pressure cylinder 7 of the steam turbine. elep X is the enthalpy value at the end of the exhaust expansion line of the low-pressure cylinder 7 of the steam turbine, X is the steam dryness at the end of the exhaust expansion line, and EL is the exhaust loss of the last stage of the low-pressure cylinder 7.

[0121] In some embodiments of this example, the above-mentioned calculation of the work done by the low-pressure cylinder 7 based on the calculated useful energy endpoint enthalpy of the exhaust steam of the low-pressure cylinder 7 and the assumed steam inlet flow rate of the low-pressure cylinder 7, to obtain the assumed work done by the low-pressure cylinder 7, includes:

[0122] According to formula W L-5 =M LP ×(H LP -H5) / 3.6 Calculate the work done by the steam intake of the low-pressure cylinder 7 to the fifth stage extraction steam 21;

[0123] According to formula W 5-6 =(M LP Calculate the work done by the fifth-stage extraction steam 21 to the sixth-stage extraction steam 22 using the formula -M5)×(H5-H6) / 3.6.

[0124] According to formula W 6-7 =(M LP Calculate the work done by extracting steam from stage 6 (M5-M6)×(H6-H7) / 3.6 to extract steam from stage 7 (M6-M6)×(H6-H7) / 3.6.

[0125] According to formula W 7-8 =(M LP -M5-M6-M7)×(H7-H8) / 3.6 Calculate the work done by the extraction steam from the seventh stage 23 to the eighth stage 24;

[0126] According to formula W 8-ueep =(M LP -M5-M6-M7-M8)×(H8-H ueep) / 3.6 Calculate the work done by the exhaust steam from the eighth-stage extraction steam 24 to the low-pressure cylinder 7;

[0127] According to formula W LP =W L-5 +W 5-6 +W 6-7 +W 7-8 +W 8-ueep Calculate the work done by low-pressure cylinder 7 to obtain the assumed work done by low-pressure cylinder 7, where M LP Assuming the steam inlet flow rate of low-pressure cylinder 7, M 5-6 M represents the steam flow rate from stage 5 extraction steam 21 to stage 6 extraction steam 22. 6-7 M represents the steam flow rate from stage 6 extraction steam 22 to stage 7 extraction steam 23. 7-8 M represents the steam flow rate from stage 7 extraction 23 to stage 8 extraction 24. 8-ueep W is the steam flow rate from the eighth-stage extraction steam 24 to the low-pressure cylinder 7 exhaust steam. L-5 W is the power output of the steam intake from low-pressure cylinder 7 to the fifth-stage extraction steam 21. 5-6 For the work done by the fifth stage extraction steam 21 to the sixth stage extraction steam 22, W 6-7 For the work done by the sixth stage extraction steam 22 to the seventh stage extraction steam 23, W 7-8 For the work done by the seventh stage extraction steam 23 to the eighth stage extraction steam 24, W 8-ueep H represents the power output of the exhaust steam from the 24th stage of the eight-stage extraction steam to the 7th stage of the low-pressure cylinder. LP H represents the steam enthalpy of the steam entering the low-pressure cylinder 7. ueep W represents the useful energy endpoint enthalpy of the exhaust steam from low-pressure cylinder 7. LP Assuming the work done by steam in the low-pressure cylinder 7 of the turbine, H5 represents the enthalpy of the fifth-stage extraction steam (21), H6 represents the enthalpy of the sixth-stage extraction steam (22), H7 represents the enthalpy of the seventh-stage extraction steam (23), and H8 represents the enthalpy of the eighth-stage extraction steam (24). Furthermore, the enthalpy of the steam entering the low-pressure cylinder 7 is H... LP It is calculated using water and steam property calculation software based on the pressure and temperature of the steam entering the low-pressure cylinder 7.

[0128] S140: Compare the actual work done by low-pressure cylinder 7 with the assumed work done by low-pressure cylinder 7. If the absolute value of the difference between the two is greater than the preset difference threshold, update the assumed steam inlet flow rate of low-pressure cylinder 7 and repeat S130 to S140 until the absolute value of the difference between the two is not greater than the preset difference threshold, and obtain the latest assumed steam inlet flow rate of low-pressure cylinder 7.

[0129] The preset difference threshold is ε2.

[0130] Specifically, if the absolute value of the difference between the assumed work done by low-pressure cylinder 7 and the actual work done by low-pressure cylinder 7, i.e., the error value, is less than ε2, then the corresponding useful energy endpoint enthalpy value of the exhaust steam of the turbine low-pressure cylinder 7 is output as the final result. If the absolute value of the difference between the assumed work done by low-pressure cylinder 7 and the actual work done by low-pressure cylinder 7 is not less than ε2, then the steam inlet flow rate of low-pressure cylinder 7 is re-assumed, and the useful energy endpoint enthalpy value of the exhaust steam of the turbine low-pressure cylinder 7 and the assumed work done by low-pressure cylinder 7 are iteratively calculated until the absolute value of the difference between the assumed work done by low-pressure cylinder 7 and the actual work done by low-pressure cylinder 7, i.e., the error value, is less than ε2, and the corresponding useful energy endpoint enthalpy value of the exhaust steam of the turbine low-pressure cylinder 7 is output as the final result.

[0131] S150: Take the latest assumed steam inlet flow rate of low-pressure cylinder 7 and the exhaust useful energy endpoint enthalpy value of the turbine low-pressure cylinder 7 as the actual useful energy endpoint enthalpy value, and output the actual useful energy endpoint enthalpy value.

[0132] Specifically, after the iterative calculation is completed, the actual useful energy endpoint enthalpy value can be obtained.

[0133] It should be noted that the main difficulty in performing thermodynamic calculations on the low-pressure cylinder 7 of the steam turbine lies in the fact that the last two sections of extraction and exhaust steam in the low-pressure cylinder 7 are located in the wet steam region, making it impossible to directly calculate their enthalpy using pressure and temperature. Furthermore, an effective method for measuring steam humidity is currently lacking. Currently, online calculation of the turbine exhaust enthalpy mainly employs the energy balance method. This method requires detailed calculations of the energy entering and leaving the turbine, and the measurement errors of all parameters involved in the calculation are accumulated in the results, potentially causing significant errors. The largest source of measurement error lies in the measurement error of steam flow rate in the turbine's thermodynamic system. However, current technology can already accurately measure pressure, temperature, water flow rate, and generator power, and the measurement error is sufficient to meet on-site requirements. Secondly, when a steam turbine operates under varying conditions, it is generally assumed that the relative internal efficiency of the regulating stage and the final stage changes significantly, while the efficiency of other pressure stages remains essentially constant under varying conditions. Therefore, when performing thermodynamic calculations for the low-pressure cylinder 7 of the steam turbine, it is entirely possible to assume that the internal efficiency of all stages except the final stage of the low-pressure cylinder 7 remains essentially constant, thereby deriving the enthalpy values ​​of the steam extracted from the last two sections of the low-pressure cylinder 7. This method is based on the above two points of analysis, using the work done by the low-pressure cylinder 7 of the steam turbine as a benchmark, and iteratively calculating the steam inlet flow rate of the low-pressure cylinder 7. This avoids the measurement errors caused by measuring the steam inlet flow rate of the feedwater pump turbine, the flow rate of the auxiliary steam header, and the flow rate of the intermediate exhaust heating steam. Secondly, when calculating under varying operating conditions, the principle that the efficiency within each stage from the sixth extraction stage 22 to the seventh extraction stage 23 and from the seventh extraction stage 23 to the eighth extraction stage 24 remains basically unchanged is used to determine the enthalpy and entropy values ​​of the seventh extraction stage 23 and the eighth extraction stage 24. Then, the expansion process line is fitted within a small range, and the endpoint enthalpy value of the exhaust expansion line of the low-pressure cylinder 7 of the turbine is iteratively calculated. Finally, the useful energy endpoint enthalpy of the exhaust of the low-pressure cylinder 7 of the turbine is derived.

[0134] In the above implementation process, this method calculates the actual work done by the low-pressure cylinder 7 based on the energy balance method. After iteratively calculating the exhaust state parameters of the low-pressure cylinder 7 according to the turbine operating parameters, the method calculates the useful energy endpoint enthalpy of the exhaust steam and the work done by the steam in the low-pressure cylinder 7 based on the assumed inlet steam flow rate and exhaust state parameters. Then, by comparing the actual work done by the low-pressure cylinder 7 with the assumed work done by the low-pressure cylinder 7, if the absolute value of the difference is greater than a preset difference threshold, the assumed inlet steam flow rate of the low-pressure cylinder 7 is updated, and the useful energy endpoint enthalpy of the exhaust steam is iteratively calculated. After the iterative calculation is completed, the actual useful energy endpoint enthalpy is obtained. Furthermore, by combining the energy balance method with the work done by the low-pressure cylinder 7 of the steam turbine as the benchmark, the steam inlet flow rate of the low-pressure cylinder 7 is calculated iteratively. This avoids the influence of measurement errors caused by the measurement of the steam inlet flow rate of the feedwater pump turbine, the flow rate of the auxiliary steam header, and the flow rate of the intermediate exhaust heating steam, thereby ensuring the accuracy of the calculation of the useful energy endpoint enthalpy value of the exhaust steam of the low-pressure cylinder 7. This method and system have the characteristics of requiring few calculation parameters, fast iteration convergence, and high accuracy. They can be applied to online monitoring of the efficiency of the low-pressure cylinder 7 of the steam turbine and online economic analysis. For field personnel, this method and system can also be used to quickly estimate the exhaust steam enthalpy of the low-pressure cylinder 7 based on the work done by the low-pressure cylinder 7, demonstrating good application value.

[0135] Figure 5 This is a block diagram of a steam turbine exhaust enthalpy calculation system provided in one embodiment of the present invention. Figure 5 As shown, an embodiment of the present invention provides a turbine exhaust enthalpy calculation system, comprising:

[0136] The actual low-pressure cylinder work calculation module is used to collect turbine operating parameters and calculate the actual low-pressure cylinder 7 work based on the energy balance method.

[0137] The low-pressure cylinder exhaust state parameter iterative calculation module is used to iteratively calculate the exhaust state parameters of the low-pressure cylinder 7 of the steam turbine based on the turbine operating parameters;

[0138] The assumed low-pressure cylinder work calculation module is used to calculate the useful energy endpoint enthalpy of the turbine low-pressure cylinder 7 exhaust based on the exhaust state parameters of the low-pressure cylinder 7 and the assumed steam flow rate of the low-pressure cylinder 7. Based on the calculated useful energy endpoint enthalpy of the turbine low-pressure cylinder 7 exhaust and the assumed steam flow rate of the low-pressure cylinder 7, the work of the low-pressure cylinder 7 is calculated to obtain the assumed work of the low-pressure cylinder 7.

[0139] The repeated execution module is used to compare the actual work done by the low-pressure cylinder 7 with the assumed work done by the low-pressure cylinder 7. If the absolute value of the difference between the two is greater than the preset difference threshold, the assumed steam flow rate of the low-pressure cylinder 7 is updated and the assumed work done by the low-pressure cylinder is repeatedly executed until the absolute value of the difference between the two is no greater than the preset difference threshold, and the latest assumed steam flow rate of the low-pressure cylinder 7 is obtained.

[0140] The actual useful energy endpoint enthalpy output module is used to take the latest assumed steam inlet flow rate of low-pressure cylinder 7 and corresponding exhaust steam useful energy endpoint enthalpy value of turbine low-pressure cylinder 7 as the actual useful energy endpoint enthalpy value, and output the actual useful energy endpoint enthalpy value.

[0141] Specifically, the system calculates the actual work done by the low-pressure cylinder 7 using the energy balance method. Based on the turbine operating parameters, the system iteratively calculates the exhaust state parameters of the low-pressure cylinder 7. Then, based on the assumed inlet steam flow rate and exhaust state parameters of the low-pressure cylinder 7, it calculates the useful energy endpoint enthalpy of the exhaust steam and the work done by the steam in the low-pressure cylinder 7 to obtain the assumed work done by the low-pressure cylinder 7. By comparing the actual work done by the low-pressure cylinder 7 with the assumed work done by the low-pressure cylinder 7, if the absolute value of the difference is greater than a preset difference threshold, the assumed inlet steam flow rate of the low-pressure cylinder 7 is updated, and the useful energy endpoint enthalpy of the exhaust steam is iteratively calculated. After the iterative calculation is completed, the actual useful energy endpoint enthalpy is obtained. Furthermore, by combining the energy balance method with the work done by the low-pressure cylinder 7 of the steam turbine as the benchmark, the steam inlet flow rate of the low-pressure cylinder 7 is calculated iteratively. This avoids the influence of measurement errors caused by the measurement of the steam inlet flow rate of the feedwater pump turbine, the flow rate of the auxiliary steam header, and the flow rate of the intermediate exhaust heating steam, thereby ensuring the accuracy of the calculation of the useful energy endpoint enthalpy value of the exhaust steam of the low-pressure cylinder 7. This method and system have the characteristics of requiring few calculation parameters, fast iteration convergence, and high accuracy. They can be applied to online monitoring of the efficiency of the low-pressure cylinder 7 of the steam turbine and online economic analysis. For field personnel, this method and system can also be used to quickly estimate the exhaust steam enthalpy of the low-pressure cylinder 7 based on the work done by the low-pressure cylinder 7, demonstrating good application value.

[0142] As one implementation scenario of this embodiment, a 660MW supercritical unit in a domestic thermal power plant has a regenerative system layout of 3 high-pressure turbines + 4 low-pressure turbines + deaerator 15. The turbine exhaust enthalpy calculation method and the system-proposed calculation method were used to verify the 100% THA, 75% THA, and 50% THA heat balance diagrams of this unit. During the calculation, the stage efficiencies from stage 6 extraction 22 to stage 7 extraction 23 and from stage 7 extraction 23 to stage 8 extraction 24 were based on the stage efficiency values ​​under the 100% THA condition. The calculation results are shown in Table 1. The relative errors between the useful energy endpoint enthalpy of the turbine low-pressure cylinder 7 exhaust calculated by this method and system and the design value are -0.18%, 0.06%, and 0.13%, respectively, which are basically consistent with the design value.

[0143] Table 1. Calculation results of low-pressure cylinder exhaust enthalpy for a 660MW unit in China

[0144]

[0145]

[0146] The present invention also provides a machine-readable storage medium storing instructions that, when executed by a processor, configure the processor to perform the above-described method for calculating the exhaust enthalpy of steam turbines.

[0147] Machine-readable storage media include both permanent and non-permanent, removable and non-removable media, which can store information by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0148] The present invention also provides an electronic device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the above-described method for calculating the exhaust enthalpy of steam turbines.

[0149] like Figure 6 The diagram shown is a schematic representation of an electronic device according to an embodiment of the present invention. Figure 6 As shown, the electronic device 10 of this embodiment includes a processor 100, a memory 101, and a computer program 102 stored in the memory 101 and executable on the processor 100. When the processor 100 executes the computer program 102, it implements the steps in the method embodiment described above. Alternatively, when the processor 100 executes the computer program 102, it implements the functions of each module / unit in the device embodiment described above.

[0150] For example, computer program 102 can be divided into one or more modules / units, one or more of which are stored in memory 101 and executed by processor 100 to complete the present invention. One or more modules / units can be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of computer program 102 in electronic device 10. For example, computer program 102 can be divided into a module for calculating the actual low-pressure cylinder work, a module for iteratively calculating the low-pressure cylinder exhaust state parameters, a module for calculating the assumed low-pressure cylinder work, a repetitive execution module, and a module for outputting the actual useful energy endpoint enthalpy value.

[0151] Electronic device 10 can be a desktop computer, laptop, handheld computer, cloud server, or other computing device. Electronic device 10 may include, but is not limited to, processor 100 and memory 101. Those skilled in the art will understand that... Figure 6 This is merely an example of electronic device 10 and does not constitute a limitation on electronic device 10. It may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device may also include input / output devices, network access devices, buses, etc.

[0152] The processor 100 can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0153] The memory 101 can be an internal storage unit of the electronic device 10, such as a hard disk or RAM of the electronic device 10. The memory 101 can also be an external storage device of the electronic device 10, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the electronic device 10. Furthermore, the memory 101 can include both internal and external storage units of the electronic device 10. The memory 101 is used to store computer programs and other programs and data required by the electronic device 10. The memory 101 can also be used to temporarily store data that has been output or will be output.

[0154] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0155] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0156] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0157] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0158] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0159] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. 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 apparatus that includes that element.

[0160] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for calculating the exhaust enthalpy of a steam turbine, characterized in that, include: S110: Collect turbine operating parameters and calculate the actual work done by the low-pressure cylinder based on the energy balance method; S120: Iteratively calculate the exhaust state parameters of the low-pressure cylinder of the steam turbine based on the aforementioned steam turbine operating parameters; S130: Calculate the useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust based on the low-pressure cylinder exhaust state parameters and the assumed low-pressure cylinder inlet flow rate; calculate the low-pressure cylinder work based on the calculated useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust and the assumed low-pressure cylinder inlet flow rate; and obtain the assumed low-pressure cylinder work. S140: Compare the actual low-pressure cylinder work and the assumed low-pressure cylinder work. If the absolute value of the difference between the two is greater than the preset difference threshold, update the assumed low-pressure cylinder steam flow rate and repeat S130 to S140 until the absolute value of the difference between the two is not greater than the preset difference threshold, and obtain the latest assumed low-pressure cylinder steam flow rate. S150: Take the latest assumed low-pressure cylinder inlet steam flow rate corresponding to the turbine low-pressure cylinder exhaust useful energy endpoint enthalpy value as the actual useful energy endpoint enthalpy value, and output the actual useful energy endpoint enthalpy value.

2. The method for calculating the exhaust enthalpy of a steam turbine according to claim 1, characterized in that, The exhaust state parameters of the turbine low-pressure cylinder include the enthalpy value at the end of the exhaust expansion line and the steam dryness at the end of the exhaust expansion line. The turbine operating parameters include at least the low-pressure cylinder exhaust pressure; The iterative calculation of the turbine low-pressure cylinder exhaust state parameters based on the turbine operating parameters includes: A1: Pre-assuming the enthalpy H at the end of the exhaust expansion line of the low-pressure cylinder of the steam turbine. elep ; A2: Based on the low-pressure cylinder exhaust pressure and the assumed H elep Calculate the entropy value S corresponding to the endpoint of the exhaust expansion line of the low-pressure cylinder of the steam turbine. elep ; A3: The entropy value S elep Substituting into the expansion process line equation, the enthalpy H at the endpoint of the low-pressure cylinder exhaust expansion line of the steam turbine is calculated. i elep ; A4: Calculate the hypothesis H elep With enthalpy H i elep If the error value does not meet the first preset error requirement, then H is re-assumed. elep And based on the re-hypothesized H elep Repeat steps A2 to A4 until the error value meets the first preset error requirement, and obtain the final enthalpy value H at the end of the exhaust expansion line of the low-pressure cylinder of the steam turbine. elep ; A5: Based on the low-pressure cylinder exhaust pressure and the final enthalpy value H elep Calculate the steam dryness at the end of the exhaust expansion line.

3. The method for calculating the exhaust enthalpy of a steam turbine according to claim 2, characterized in that, The steam turbine's extraction system includes six-stage extraction, seven-stage extraction, and eight-stage extraction. The entropy value S elep Before substituting into the expansion process line equation, the following is also included: Based on the stage efficiency from the sixth stage extraction to the seventh stage extraction and the stage efficiency from the seventh stage extraction to the eighth stage extraction, calculate the enthalpy of the seventh stage extraction, the enthalpy of the eighth stage extraction, the entropy of the seventh stage extraction, and the entropy of the eighth stage extraction. Based on the enthalpy values ​​of the seven-stage extraction steam, the enthalpy values ​​of the eight-stage extraction steam, the entropy values ​​of the seven-stage extraction steam, and the entropy values ​​of the eight-stage extraction steam, the expansion process line equation from the seventh stage extraction steam to the end point of the low-pressure cylinder exhaust steam of the turbine is fitted. Wherein, H8 is the enthalpy of the eight-stage extraction steam, H7 is the enthalpy of the seven-stage extraction steam, S8 is the entropy of the eight-stage extraction steam, and S7 is the entropy of the seven-stage extraction steam.

4. The method for calculating the exhaust enthalpy of a steam turbine according to claim 3, characterized in that, The formula for calculating the enthalpy of the seven-stage extraction is H7 = H6 - η. 6-7 ×(H6-H s7 The formula for calculating the enthalpy of the eight-segment extraction steam is H8 = H7 - η / 100. 7-8 ×(H7-H s8 The formula for calculating the entropy of the seven-stage extraction steam is S7 = f / 100. S (P7,H7), the formula for calculating the entropy value of the eight-section steam extraction is S8=f S (P8,H8), where H6 is the enthalpy value of the six-stage extraction steam calculated based on the six-stage extraction steam pressure and temperature, H... s7 H is the isentropic enthalpy of the seven-stage extraction steam, calculated based on the entropy values ​​of the six-stage extraction steam and the pressure of the seven-stage extraction steam, and the entropy values ​​of the six-stage extraction steam are obtained based on the pressure and temperature of the six-stage extraction steam. s8 The isentropic enthalpy values ​​of the eight-stage extraction steam are calculated based on the entropy values ​​of the seven-stage extraction steam and the pressures of the eight-stage extraction steam. P7 represents the pressure of the seven-stage extraction steam, P8 represents the pressure of the eight-stage extraction steam, and η represents the isentropic enthalpy values ​​of the eight-stage extraction steam. 6-7 For the stage efficiency of six-stage extraction to seven-stage extraction, η 7-8 The efficiency ranges from seven-stage to eight-stage steam extraction.

5. The method for calculating the exhaust enthalpy of a steam turbine according to claim 1, characterized in that, The calculation of the actual work done by the low-pressure cylinder based on the energy balance method includes: The first work quantity is calculated based on the steam flow rate and steam enthalpy of each stage from the main steam of the steam turbine to the high-pressure cylinder. The second work quantity is calculated based on the steam flow rate and steam enthalpy of each stage of the reheat steam from the steam turbine to the intermediate pressure cylinder. The actual low-pressure cylinder work is calculated based on the first work amount and the second work amount.

6. The method for calculating the exhaust enthalpy of a steam turbine according to claim 5, characterized in that, The steam turbine's extraction system includes a steam extraction section; The calculation of the first work quantity based on the steam flow rate and steam enthalpy of each stage from the main steam of the steam turbine to the high-pressure cylinder includes: According to formula W z-t =M z-t ×(H z -H t ) / 3.6 Calculate the work done by the main steam from the turbine to the regulating stage of the turbine, where W z-t The work done by the main steam after it reaches the regulating stage, M z-t Steam flow rate after main steam reaches the regulating stage, H z The enthalpy of the main steam, H t The enthalpy of the steam after the regulating stage; According to formula W t-1 =M t-1 ×(H t -H1) / 3.6 Calculate the work done by the turbine from the regulating stage to the first-stage extraction, where W t-1 To regulate the power output of the extraction stage, M t-1 To regulate the steam flow rate from the regulating stage to the first stage extraction steam, H t H1 is the steam enthalpy after the regulating stage, and H1 is the steam enthalpy of the first stage of steam extraction. According to formula W 1-g =M 1-g ×(H1-H g ) / 3.6 Calculate the work done by the extraction of steam to the high-pressure cylinder exhaust, where W 1-g M represents the work done by the extraction of steam to the high-pressure cylinder for exhaust. 1-g H1 is the steam flow rate from the extraction stage to the high-pressure cylinder exhaust steam, and H1 is the steam enthalpy of the extraction stage. g This refers to the steam enthalpy value of the exhaust steam from the high-pressure cylinder. According to formula W HP =W z-t +W t-1 +W 1-g The first work done is obtained, where W HP This represents the initial work done by steam in the high-pressure cylinder of the steam turbine.

7. The method for calculating the exhaust enthalpy of a steam turbine according to claim 5, characterized in that, The steam turbine's extraction system includes three extraction stages; The calculation of the second work quantity based on the steam flow rate and steam enthalpy of each stage of the reheat steam from the turbine to the intermediate-pressure cylinder includes: According to formula W zr-3 =M zr-3 ×(H zr -H3) / 3.6 yields the work done by the reheated steam to the third-stage extraction, where W zr-3 M represents the work done by the reheated steam to the third stage extraction steam. zr-3 H is the steam flow rate from reheat steam to the third stage extraction steam. zr H3 is the steam enthalpy of the reheat steam, and H4 is the steam enthalpy of the three-stage extraction steam. According to formula W 3-ip =M 3-ip ×(H3-H ip The work done by the three-stage extraction of steam to the intermediate-pressure cylinder exhaust is obtained from W / 3.

6. 3-ip M represents the work done by the three-stage extraction of steam to the intermediate-pressure cylinder exhaust. 3-ip H represents the steam flow rate from the three-stage extraction steam to the intermediate-pressure cylinder exhaust. ip This refers to the steam enthalpy value of the exhaust steam from the intermediate-pressure cylinder. According to formula W IP =W zr-3 +W 3-ip The work done by the intermediate pressure cylinder is obtained, where W IP This is the second amount of work done by steam in the intermediate pressure cylinder of the steam turbine.

8. The method for calculating the exhaust enthalpy of a steam turbine according to claim 5, characterized in that, The calculation formula for calculating the actual low-pressure cylinder work based on the first work and the second work is as follows: W LP =W e / (η m ·η e ·10 -4 )-W HP -W IP Among them, W LP W represents the actual work done by the low-pressure cylinder. e η is the power of the steam turbine generator set. m For mechanical efficiency, η e For generator efficiency, W HP For the first amount of work done, W IP This is the second amount of work done.

9. The method for calculating the exhaust enthalpy of a steam turbine according to claim 2, characterized in that, The calculation of the useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust based on the low-pressure cylinder exhaust state parameters and the assumed low-pressure cylinder inlet steam flow rate includes: Pre-assuming low-pressure cylinder inlet steam flow rate M LP ; Based on the assumption that the low-pressure cylinder inlet steam flow rate M LP The useful energy endpoint enthalpy of the exhaust steam at the end of the exhaust expansion line and the enthalpy value at the end of the exhaust steam expansion line of the turbine low-pressure cylinder are used to calculate the useful energy endpoint enthalpy value of the exhaust steam of the turbine low-pressure cylinder.

10. The method for calculating the exhaust enthalpy of a steam turbine according to claim 9, characterized in that, The assumption is that the low-pressure cylinder inlet steam flow rate M LP The calculation of the useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust steam, based on the steam dryness fraction at the endpoint of the exhaust expansion line and the enthalpy value at the endpoint of the exhaust expansion line, includes: Based on the assumption that the low-pressure cylinder inlet steam flow rate M LP The exhaust loss EL of the last stage of the low-pressure cylinder is calculated. According to formula H ueep =H elep -0.87×X×EL yields the endpoint enthalpy of useful energy from the exhaust steam of the low-pressure cylinder of the steam turbine, where H ueep H represents the useful energy endpoint enthalpy of exhaust steam from the low-pressure cylinder of the steam turbine. elep X represents the enthalpy value at the end of the exhaust expansion line of the low-pressure cylinder of the steam turbine, X represents the steam dryness at the end of the exhaust expansion line, and EL represents the exhaust loss of the last stage of the low-pressure cylinder.

11. The method for calculating the exhaust enthalpy of a steam turbine according to claim 10, characterized in that, The steam turbine's extraction system includes five-stage extraction, six-stage extraction, seven-stage extraction, and eight-stage extraction. The assumption is that the low-pressure cylinder inlet steam flow rate M LP The calculated exhaust loss EL of the last stage of the low-pressure cylinder includes: Calculate the steam extraction flow rates for the fifth, sixth, seventh, and eighth stages respectively. According to formula M e =M LP -M5-M6-M7-M8+M LPz Calculate the low-pressure cylinder exhaust flow rate, where M e M is the exhaust flow rate of the low-pressure cylinder of the steam turbine. LPz M5 is the steam inlet flow rate for the low-pressure cylinder shaft seal, M6 is the steam extraction flow rate for five stages, M7 is the steam extraction flow rate for six stages, M8 is the steam extraction flow rate for seven stages, and M8 is the steam extraction flow rate for eight stages. Calculate the specific volume V of the low-pressure cylinder exhaust based on the low-pressure cylinder exhaust pressure and the enthalpy at the end of the low-pressure cylinder exhaust expansion line. e ; According to formula Q e =M e / V e The volumetric flow rate Q of the low-pressure cylinder exhaust is obtained. e ; The volumetric flow rate Q of the exhaust gas from the low-pressure cylinder e Inputting into a preset relationship table, the low-pressure cylinder final stage exhaust loss EL is obtained through matching, wherein the preset relationship table includes Q. e The correspondence between EL and EL.

12. The method for calculating the exhaust enthalpy of a steam turbine according to claim 11, characterized in that, The formulas for calculating the steam flow rates of the five-stage, six-stage, seven-stage, and eight-stage extraction stages are as follows: Among them, M n For condensate flow rate, H 5c The enthalpy of the outlet water at No. 5 is H. 5j H5 is the enthalpy of the inlet water at the No. 5 low-pressure heater, and H5 is the enthalpy of the extraction steam at the fifth stage. 5s The enthalpy of hydrophobicity is H, which is the value of the No. 5 low-pressure hydrophobic 6c The enthalpy of the outlet water at No. 6 low pressure, H 6j H6 is the enthalpy of the inlet water at the No. 6 low-pressure heater, and H6 is the enthalpy of the extraction steam at the sixth stage. 6s The enthalpy of hydrophobicity of No. 6 is H. 7c The enthalpy of the water discharged from the No. 7 low-pressure heater is H. 7j H7 is the enthalpy of the inlet water at the No. 7 low-pressure heater, and H7 is the enthalpy of the extraction steam at the seventh stage. 7s The enthalpy of hydrophobicity of No. 7 is H. 8c The enthalpy of the water discharged from the No. 8 low-pressure heater, H 8j H8 is the enthalpy of the inlet water at the No. 8 low-pressure heater, and H8 is the enthalpy of the steam extraction at the eighth stage. 8s The enthalpy value is the hydrophobic value of No.

8.

13. The method for calculating the exhaust enthalpy of a steam turbine according to claim 11, characterized in that, The calculation of the work done by the low-pressure cylinder based on the calculated useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust and the assumed low-pressure cylinder inlet steam flow rate, to obtain the assumed low-pressure cylinder work, includes: According to formula W L-5 =M LP ×(H LP -H5) / 3.6 Calculate the work done from the low-pressure cylinder steam intake to the fifth stage steam extraction; According to formula W 5-6 =(M LP -M5)×(H5-H6) / 3.6 Calculate the work done from the fifth stage extraction to the sixth stage extraction; According to formula W 6-7 =(M LP -M5-M6)×(H6-H7) / 3.6 Calculate the work done from the sixth stage extraction to the seventh stage extraction; According to formula W 7-8 =(M LP -M5-M6-M7)×(H7-H8) / 3.6 Calculate the work done from the seventh stage extraction to the eighth stage extraction; According to formula W 8-ueep =(M LP -M5-M6-M7-M8)×(H8-H ueep ) / 3.6 Calculate the work done by the eight-stage extraction steam to the low-pressure cylinder exhaust; According to formula W LP =W L-5 +W 5-6 +W 6-7 +W 7-8 +W 8-ueep Calculate the work done by the low-pressure cylinder to obtain the assumed work done by the low-pressure cylinder, where M LP Assuming the low-pressure cylinder inlet steam flow rate, M 5-6 M represents the steam flow rate from the fifth stage extraction to the sixth stage extraction. 6-7 M represents the steam flow rate from the sixth to the seventh stage of extraction. 7-8 M represents the steam flow rate from the seventh to the eighth stage of extraction. 8-ueep W represents the steam flow rate from the eight-stage extraction steam to the low-pressure cylinder exhaust. L-5 W is the work done from the low-pressure cylinder intake to the fifth stage extraction. 5-6 W represents the work done by steam extraction from stage five to stage six. 6-7 W represents the work done by steam extraction from stage six to stage seven. 7-8 W represents the work done by steam extraction from stage seven to stage eight. 8-ueep H represents the work done by the eight-stage extraction steam to the low-pressure cylinder exhaust. LP H represents the steam enthalpy of the steam entering the low-pressure cylinder. ueep W represents the useful energy endpoint enthalpy of the low-pressure cylinder exhaust. LP H5 represents the assumed work done by steam in the low-pressure cylinder of the turbine, H6 represents the enthalpy of the fifth extraction stage, H7 represents the enthalpy of the sixth extraction stage, and H8 represents the enthalpy of the seventh extraction stage.

14. A steam turbine exhaust enthalpy calculation system, characterized in that, include: The actual low-pressure cylinder work calculation module is used to collect turbine operating parameters and calculate the actual low-pressure cylinder work based on the energy balance method. The low-pressure cylinder exhaust state parameter iterative calculation module is used to iteratively calculate the turbine low-pressure cylinder exhaust state parameters based on the turbine operating parameters. The assumed low-pressure cylinder work calculation module is used to calculate the useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust based on the exhaust state parameters of the low-pressure cylinder and the assumed low-pressure cylinder inlet flow rate, and to calculate the work of the low-pressure cylinder based on the calculated useful energy endpoint enthalpy of the turbine low-pressure cylinder exhaust and the assumed low-pressure cylinder inlet flow rate, thereby obtaining the assumed low-pressure cylinder work. The repeated execution module is used to compare the actual low-pressure cylinder work and the assumed low-pressure cylinder work. If the absolute value of the difference between the two is greater than a preset difference threshold, the assumed low-pressure cylinder steam flow rate is updated and the assumed low-pressure cylinder work calculation module is repeatedly executed until the absolute value of the difference between the two is not greater than the preset difference threshold, and the latest assumed low-pressure cylinder steam flow rate is obtained. The actual useful energy endpoint enthalpy output module is used to take the latest assumed low-pressure cylinder inlet steam flow rate corresponding to the turbine low-pressure cylinder exhaust useful energy endpoint enthalpy value as the actual useful energy endpoint enthalpy value, and output the actual useful energy endpoint enthalpy value.

15. A machine-readable storage medium storing instructions thereon, characterized in that, When executed by a processor, this instruction causes the processor to be configured to perform the turbine exhaust enthalpy calculation method according to any one of claims 1 to 13.

16. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the turbine exhaust enthalpy calculation method according to any one of claims 1 to 13.

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