A method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units

Abstract

This invention relates to the fields of energy management systems and cogeneration optimization technology, and particularly to a method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units. The method includes: mathematically expressing the extraction steam volume of each section of the unit's regenerative system; sequentially acquiring the outlet flow data of each section; establishing a pressure calculation model for the flow path using a simplified variable-condition thermodynamic calculation method for the steam turbine and the work process of energy conversion within each stage; obtaining the heat exchange process characteristics of each stage heater unit by combining the heater heat balance equation and the mathematical model of the heat transfer process, and establishing a thermodynamic calculation model for the regenerative system; correcting the pressure of the flow path of the heating unit using the returned data from the thermodynamic calculation model of the regenerative system, forming a complete iterative algorithm for the heating unit, and finally obtaining the real-time power generation load of the heating unit. This invention can be used for real-time power generation load calculation and performance analysis of heating units, comprehensively ensuring the power generation output and heating / steam supply safety of the heating unit, and improving energy utilization efficiency.

Description

Technical Field

[0001] This invention relates to the fields of energy management systems and cogeneration optimization technology, and in particular to a method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units. Background Technology

[0002] Real-time calculation of the power generation load of heating units involves real-time monitoring of the unit's operating status, data collection and analysis, and precise calculation and adjustment of the unit's power generation load based on this data. Real-time calculation ensures that the unit optimizes power output while meeting the needs of heat users, improves the unit's thermodynamic cycle, and significantly increases energy efficiency. This is crucial for coordinating the power generation output guarantee of heating units with the safety of heating and steam supply. However, most existing algorithms for real-time calculation of the power generation load of heating units are time-consuming and labor-intensive, making them difficult to implement in engineering projects. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a real-time calculation method for the power generation load of multi-stage heating extraction steam turbine units. This method can accurately calculate the real-time power generation load of heating units under different operating conditions, coordinate the power generation output guarantee and heating and steam supply safety of heating units, and improve energy utilization efficiency.

[0004] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0005] This invention provides a method for real-time calculation of power generation load of a multi-stage heating extraction steam turbine unit, comprising the following steps:

[0006] S1. Based on the heat balance diagram of the heating unit under different operating conditions, the steam extraction data of each section of the heating unit is fitted with a formula to obtain the outlet flow data of each section and to obtain the mathematical expression of the regenerative system.

[0007] S2. Based on the structural characteristics of the steam extraction port distribution of the heating unit, the unit is divided into sections. The pressure of the turbine flow passage is calibrated based on the mathematical expression of the steam extraction port flow data, and the steam extraction pressure data of each section is obtained.

[0008] S3. Using the isentropic enthalpy drop theory in the simplified variable operating condition thermodynamic calculation method, obtain the enthalpy data of each section of extraction steam, call the steam property function to obtain the temperature data of each section of extraction steam, and establish a pressure calculation model for the flow path of the heating unit.

[0009] S4. Based on the pressure calculation model of the flow path of the heating unit, the extraction steam pressure data of each section and the upper and lower end difference data of each level of heater in the heat balance diagram of the heating unit are obtained. The enthalpy data of condensate and condensate at the outlet of each level of heater are obtained through the steam property function.

[0010] S5. By using the mass conservation equation, energy conservation equation and heat transfer process model of the heater in the regenerative system, obtain the heat balance equation and heat exchange process characteristics of each heater unit.

[0011] S6. Based on the heat balance equations of each heater unit, obtain the steam extraction data of each section on the turbine side and establish a thermodynamic calculation model of the regenerative system.

[0012] S7. Based on the highly coupled mechanism of the pressure calculation model of the flow path and the thermodynamic calculation model of the regenerating system, the return data of the thermodynamic calculation model of the regenerating system is used to correct the pressure of the flow path of the heating unit, and the thermodynamic calculation data of the regenerating system is used to replace the steam extraction data of each section on the turbine side to form a cyclic iterative algorithm for the heating unit.

[0013] S8. The real-time power generation load of the heating unit is obtained by iterative calculation of the pressure calculation model of the steam turbine flow path and the thermodynamic calculation model of the regenerating system, as well as the calculation of the unit efficiency.

[0014] Furthermore, step S1 is detailed as follows:

[0015] The design condition is set as 100% THA (Total Heat Amount) without steam extraction for heating. Combining the heat balance diagrams of the heating unit under different operating conditions, the mathematical relationships are obtained as follows: (The ratio of main steam flow rate data to the main steam flow rate data under the design condition, the extraction steam rate data for each segment in the heat balance diagram of the heating unit, and the outlet flow rate data for each segment.)

[0016] G i，1 =G i-1，1 -G e，i =G i-1，1 -(ax 6 +bx 5 +cx 4 +dx 3 +ex 2 +fx+g);

[0017] The formula for calculating the steam extraction volume of each section of the heating unit is as follows:

[0018] G e，i =ax 6 +bx 5 +cx 4 +dx 3 +ex 2 +fx+g;

[0019] The ratio of the main steam flow rate data to the main steam flow rate data under design conditions is:

[0020]

[0021] In the formula, G i，1 G i-1，1These represent the current and previous export flow rates, respectively, in kg / s; G e，i This represents the extraction steam flow rate data for each section of the unit, in kg / s, where a, b, c, d, e, f, and g are determined by the heat balance diagram of the heating unit under different operating conditions; x represents the ratio of the main steam flow rate to the main steam flow rate data under design operating conditions; G 0，1 G0 and G0 represent the main steam flow rate data under variable operating conditions and design operating conditions, respectively, in kg / s, i = 1, 2, 3, 4, 5, 6, 7, 8.

[0022] Furthermore, step S2 is detailed as follows:

[0023] The steam turbine is divided into high-pressure, intermediate-pressure, and low-pressure cylinders according to its operating pressure. The power-generating section of the turbine is further segmented by incorporating the extraction ports of each regenerative system. A variable-condition thermodynamic calculation mathematical model is established to calibrate the pressure of the turbine's flow path. Based on the approximate proportional relationship between flow rate and pressure in the flow path, the calculation formula for the extraction pressure data of each section during variable-condition operation of the steam turbine is as follows:

[0024]

[0025] In the formula, P e，i P i These represent the extraction steam pressure data for each section under varying operating conditions and design operating conditions, in bar; G i，1 G i The values ​​represent the steam extraction port flow rates for each section under varying operating conditions and design operating conditions, respectively, in kg / s, i = 1, 2, 3, 4, 5, 6, 7, 8.

[0026] Furthermore, step S3 is as follows:

[0027] Given the main steam pressure and temperature data, the main steam enthalpy data H is obtained through the steam property function. 0，1 With the main steam entropy data S 0，1 For a section of extraction steam pressure data P e，1 By combining the theory of isentropic enthalpy drop, a range of isentropic outlet specific enthalpy data h is obtained. j，1 Calculate a segment of extraction steam enthalpy data; the formula for obtaining a segment of extraction steam enthalpy data is:

[0028] H e，1 =H 0，1 -(H 0，1 -h j，1 )×j1;

[0029] In the formula, H e，1 This represents a range of extraction enthalpy data, in kJ / kg; H 0，1 This represents the main steam enthalpy data, in kJ / kg; h j，1j1 represents a segment of isentropic outlet enthalpy data, kJ / kg; j1 represents a segment of relative internal efficiency.

[0030] The extraction steam pressure and enthalpy data for this section are used to obtain the outlet entropy data for this section through the steam property function. These two data points then serve as the inlet parameters for the next extraction section, and the extraction parameters for the next section are calculated sequentially. The formula for obtaining the enthalpy data for each extraction section is as follows:

[0031] H e，i =H e，i-1 -(H e，i-1 -h j，i )×J i ;

[0032] In the formula, H e，i This represents the enthalpy data of each extraction stage, in kJ / kg; H. e，i-1 This represents the inlet enthalpy data for each segment, i.e., the enthalpy data of the previous extraction steam segment, in kJ / kg; h j，i This represents the isentropic outlet enthalpy data for each segment, in kJ / kg; j i Let i represent the relative internal efficiency of each segment, i = 1, 2, 3, 4, 5, 6, 7, 8.

[0033] Furthermore, step S4 is detailed as follows:

[0034] Condensate pressure data at the outlet of each heater (p) w，i Compared with the inlet condensate pressure data p w，i+1 Pressure loss exists, determined based on the heating unit's heat balance diagram; the calculation formula for obtaining the drain pressure data of each stage heater is:

[0035] p d，i =P e，i ×(1-a);

[0036] In the formula, p d，i This indicates the condensate pressure data for each stage of the heater, in bar; P e，i The value represents the extraction steam pressure data of each section obtained from the pressure calculation model of the flow path of the heating unit, in bar; a represents the pressure loss of each stage of the heater, which is about 2%-3%, i = 1, 2, 3, 4, 5, 6, 7, 8;

[0037] The saturated temperature data corresponding to the condensate pressure data of each stage of the heater are obtained by using the water vapor property function, and the condensate temperature data of each stage of the heater outlet is obtained. The calculation formula for obtaining the condensate temperature data of each stage of the heater outlet is:

[0038] t w，i =tb ，i -f i，s ;

[0039] In the formula, tw，i This indicates the condensate temperature data at the outlet of each heater stage, in °C; t b，i This represents the saturation temperature data (°C) corresponding to the condensate pressure data of each heater stage; f i，s This represents the top-end temperature difference data for each heater stage, in °C; i = 1, 2, 3, 4, 5, 6, 7, 8;

[0040] The formula for calculating the condensate temperature data of each stage of the heater is:

[0041] t d，i =t w，i+1 +f i，x ;

[0042] In the formula, t d，i This indicates the condensate temperature data for each stage of the heater, in °C; t w，i+1 This represents the condensate temperature data at the inlet of each stage of the heater, i.e., the condensate temperature data at the outlet of the next stage heater, in °C; f i，x This represents the lower-end difference data of each heater stage, in °C; i = 1, 2, 3, 4, 5, 6, 7, 8;

[0043] The enthalpy data h of the condensate inlet and outlet of each heater were obtained by using water vapor property functions to obtain the enthalpy data h of the condensate inlet of each heater. w，i+1 Enthalpy data of outlet condensate h w，i and hydrophobic enthalpy data h d，i .

[0044] Furthermore, step S5 is detailed as follows:

[0045] In the regenerative system, the heaters at each stage mainly use a portion of the steam extracted from the turbine to heat the boiler feedwater or condensate, thus achieving regenerative heating. During this process, the heaters at each stage follow the law of conservation of energy, and the total energy released by the steam due to condensation from the heater inlet to the outlet is equal to the total energy absorbed by the condensate due to heating in the corresponding process.

[0046] The heat balance equations for each stage of the heater unit in the regenerative system are as follows:

[0047] G e，i H e，i +G x h w，i+1 +G d，i-1 h d，i-1 =G x h w，i +G d，i h d，i ;

[0048] Among them, G e，i +G d，i-1 =G d，i Ge，i This indicates the steam extraction rate data for each stage of the heater, in kg / s; H. e，i This represents the enthalpy data of steam extraction from each stage of the heater, in kJ / kg; G x This represents the condensate flow rate data at the inlet and outlet of each stage of the heater, in kg / s; when i = 1, 2, 3, G in the high-pressure heater x =G 0，1 The boiler feedwater flow rate is approximately equal to the turbine main steam flow rate; when i = 5, 6, 7, 8, G in the low-pressure heater... x =G 0，2 For condensate flow rate data; h w，i h w，i+1 These represent the enthalpy values ​​of condensate at the outlet and inlet of each heater stage, in kJ / kg; G d，i-1 This indicates the condensate flow rate of the previous stage heater, in kg / s; h. d，i-1 This represents the enthalpy of the condensate from the previous stage heater, in kJ / kg; G d，i This indicates the condensate flow rate data for each stage of the heater, in kg / s and h. d，i The data represents the hydrophobic enthalpy values ​​of each heater stage, in kJ / kg; i = 1, 2, 3, 4, 5, 6, 7, 8;

[0049] Deaerator #4 is a mixing heater. It uses direct mixing of steam extracted from the turbine with water for heat transfer and deaeration. All water is mixed with steam during the heating process and flows out only after reaching saturation. No condensate requiring separate discharge is generated during this process. The heat balance equation for deaerator #4 in the regenerative system is as follows:

[0050] G e，c H e，4 +G 0，2 h w，5 +G d，3 h d，3 =G 0，1 h w，4 ;

[0051] Among them: G e，c +G 0，2 +G d，3 =G 0，1 G e，c This indicates the deaerator extraction steam rate, in kg / s; H₂ e，4 This represents the enthalpy data of deaerator extraction steam, in kJ / kg; G 0，1 This represents the boiler feedwater flow rate, approximating the turbine main steam flow rate, in kg / s; G 0，2 This represents condensate flow rate data, in kg / s; h. w，4 h w，5 These represent the enthalpy values ​​of condensate at the deaerator outlet and inlet, respectively, in kJ / kg; Gd，3 This indicates the condensate flow rate of high-pressure heater #3, in kg / s and h. d，3 This represents the enthalpy value of the condensate draining from the #3 high-pressure heater, in kJ / kg.

[0052] Furthermore, step S6 is as follows:

[0053] After processing the heat balance equations of each heater unit, the steam extraction rate data for each section on the turbine side are obtained; the calculation formulas for obtaining the steam extraction rate data for each section on the turbine side corresponding to each heater unit are as follows:

[0054] G e，i =(G x (h w，i -h w，i+1 )+G d，i-1 (h d，i -h d，i-1 )) / (H e，i -h d，i );

[0055] In the formula, G e，i This indicates the steam extraction rate data for each stage of the heater, in kg / s; G x This represents the condensate flow rate data at the inlet and outlet of each stage of the heater, in kg / s; when i = 1, 2, 3, G in the high-pressure heater x =G 0.1 The boiler feedwater flow rate is approximately equal to the turbine main steam flow rate; when i = 5, 6, 7, 8, G in the low-pressure heater... x =G 0，2 For condensate flow rate data; h w，i h w，i+1 These represent the enthalpy values ​​of condensate at the outlet and inlet of each heater stage, in kJ / kg; G d，i-1 This indicates the condensate flow rate of the previous stage heater, in kg / s; h. d，i h d，i-1 These represent the enthalpy values ​​of the condensate from each stage of the heater and the enthalpy value of the condensate from the previous stage heater, respectively, in kJ / kg; H e，i The data represents the steam extraction enthalpy of each heater stage, in kJ / kg; i = 1, 2, 3, 4, 5, 6, 7, 8;

[0056] The formula for calculating the extraction steam volume data of the turbine side corresponding to Deaerator #4 is as follows:

[0057] G e，c =(G 0，1 (h w，4 -h w，5 )+G d，3 (h w，5 -h d，3 )) / (H e，4 -h w，5);

[0058] In the formula, G e，c This indicates the deaerator extraction steam rate, expressed in kg / s; G 0，1 This represents the boiler feedwater flow rate, approximating the turbine main steam flow rate, in kg / s; h. w，4 h w，5 These represent the enthalpy values ​​of condensate at the deaerator outlet and inlet, respectively, in kJ / kg; G d，3 This indicates the condensate flow rate of high-pressure heater #3, in kg / s and h. d，3 This represents the enthalpy of the condensate from the #3 high-pressure heater, in kJ / kg; H e，4 This represents the enthalpy value of the deaerator extraction steam, in kJ / kg.

[0059] Furthermore, step S7 is detailed as follows:

[0060] The extraction steam volume data for each stage of the turbine side corresponding to each heater obtained from the thermodynamic calculation model of the regenerative system of the heating unit is used to replace the extraction steam volume data for each stage of the unit in the pressure calculation model of the flow path, which is based on the heat balance diagram fitted under different operating conditions. According to G i，1 =G i-1，1 -G e，i The outlet flow data of each section on the turbine side were obtained again;

[0061] Based on the approximate proportional relationship between flow rate and pressure in the flow path, the extraction steam pressure data of each section of the turbine is obtained during variable operating conditions. Then, the enthalpy and temperature data of each extraction section are obtained by using the isentropic enthalpy drop theory and calling the steam property function.

[0062] Based on the pressure calculation model of the flow path of the heating unit, a set of steam extraction parameter data of each section of the turbine side was obtained again. The heat balance equation of each stage of the heater unit was re-established by using the steam property function, the mass-energy conservation equation of the heater in the regenerative system and the heat transfer process model. New steam extraction data of each stage of the heater corresponding to each section of the turbine side were obtained.

[0063] Through repeated substitution and iteration of the data returned by the flow path pressure calculation model and the regenerative system thermodynamic calculation model, a cyclic iterative algorithm for the heating unit is formed. That is, the output data of the flow path pressure calculation model is used as the input value of the regenerative system thermodynamic calculation model to calculate the steam extraction volume data of each section on the turbine side, and the steam extraction volume data of each section obtained by the regenerative system thermodynamic calculation model is used as the input value of the flow path pressure calculation model to calculate and solve for the steam extraction pressure, enthalpy and other data of each section. This forms a cyclic iterative algorithm for the heating unit that uses the flow path pressure calculation model to solve for the steam extraction pressure and other data, and the regenerative system thermodynamic calculation model to solve for the steam extraction volume data.

[0064] Furthermore, step S8 is detailed as follows:

[0065] Based on the cyclic iterative algorithm of the heating unit, when the cyclic calculation continues until the steam extraction volume data of each stage heater corresponding to each section of the turbine side in the thermodynamic calculation model of the regenerating system is approximately equal to the steam extraction volume data of the next set of corresponding sections, the cyclic iterative algorithm of the heating unit ends and the final data of the steam extraction port flow rate and steam extraction enthalpy value of each section of the unit are output, which are used to calculate the real-time power generation load of the heating unit and analyze the unit performance.

[0066] The formula for calculating the power generation capacity of the high-pressure cylinder on the turbine side of the heating unit is as follows:

[0067] N HP =G 0，1 (H 0，1 -H e，1 )+G 1，1 (H e，1 -H e，2 );

[0068] The formula for calculating the power generation capacity of the intermediate-pressure cylinder on the turbine side of the heating unit is as follows:

[0069] N IP =G 2，1 (H z，1 -H e，3 )+G 3，1 (H e，3 -H e，4 );

[0070] The formula for calculating the power generation capacity of the low-pressure cylinder on the turbine side of the heating unit is as follows:

[0071] N LP =G 4，1 (H e，4 -H e，5 )+G 5，1 (H e，5 -H e，6 )+G 6，1 (H e，6 -H e，7 )+G 7，1 (H e，7 -H e，8 )+G 8，1 (H e，8 -H e，9 );

[0072] The formula for calculating the real-time power generation load on the turbine side of the heating unit is as follows:

[0073] N=(N HP +N IP +N LP )×η;

[0074] Where N represents the real-time power generation load on the turbine side of the heating unit, in MW; NHP N IP N LP These represent the real-time power generation loads (MW) of the high-pressure, intermediate-pressure, and low-pressure cylinders on the turbine side of the heating unit; G 01 This represents the main steam flow rate of the steam turbine, in kg / s; G i1 This represents the outlet flow rate data for each section of the steam turbine, in kg / s; H. 01 This represents the enthalpy of the main steam in the steam turbine, in kJ / kg; H ei This represents the enthalpy data of steam extraction from each stage of the heater, in kJ / kg; H. z1 This represents the enthalpy of the steam entering the intermediate pressure cylinder, in kJ / kg; H e9 The data represents the enthalpy of the exhaust steam from the turbine side, in kJ / kg; η = 0.982 represents the generator power; i = 1, 2, 3, 4, 5, 6, 7, 8;

[0075] In the process of calculating the extraction steam enthalpy data for each section on the turbine side, the unit efficiency, i.e., the relative internal efficiency of each section of the unit, has already been considered. The extraction steam enthalpy data for each section of the unit is known from the heat balance diagram under different operating conditions of the heating unit. Based on the extraction steam pressure data and inlet entropy data for each section, isentropic outlet specific enthalpy data is obtained through water vapor property functions, and the unit efficiency is calculated backwards.

[0076]

[0077] In the formula, j i H represents the relative internal efficiency of each section of the unit; e，i This represents the enthalpy data of each extraction stage, in kJ / kg; H. e，i-1 This represents the inlet enthalpy data for each segment, i.e., the enthalpy data of the previous extraction steam segment, in kJ / kg; h j，i Represents the isentropic outlet specific enthalpy data for each segment, kJ / kg; i = 1, 2, 3, 4, 5, 6, 7, 8;

[0078] The relative internal efficiency data of each segment in the heat balance diagram of the existing heating unit under different operating conditions are calculated. A formula is then fitted using the ratio of the main steam flow rate data to the main steam flow rate data under the design operating conditions to obtain a formula applicable to all operating conditions of the unit, j. i =hx 6 +ix 5 +jx 4 +kx 3 +lx 2 The formula for calculating the relative internal efficiency of each segment of +mx+n.

[0079] The present invention can achieve the following technical effects:

[0080] This invention provides a real-time calculation method for the power generation load of a multi-stage heating extraction turbine unit. Based on the heat balance diagram data of the heating unit, it mathematically expresses the extraction steam volume of each section of the unit's regenerative system, sequentially acquiring the outlet flow rate data of each section. Through a simplified variable-condition thermodynamic calculation method for the turbine and the work process of energy conversion within each stage, it obtains the extraction steam parameter data of each section on the turbine side of the heating unit, establishing a pressure calculation model for the flow path of the heating unit. Furthermore, it combines the heater heat balance equation and the mathematical model of the heat transfer process to obtain the heat exchange process characteristics of each stage of the heater unit, obtaining the extraction steam volume data of each section on the turbine side, and establishing a thermodynamic calculation model for the regenerative system. Based on the high coupling mechanism between the pressure calculation model of the flow path and the thermodynamic calculation model of the regenerative system, it uses the returned data from the thermodynamic calculation model of the regenerative system to correct the pressure of the flow path of the heating unit, forming a complete iterative algorithm for the heating unit, ultimately obtaining the real-time power generation load of the heating unit. This invention can be used for real-time power generation load calculation and performance analysis of heating units, helping to improve energy utilization efficiency and coordinate the power generation output guarantee and heating / steam supply safety of heating units. Attached Figure Description

[0081] Figure 1 This is a flowchart of a method for real-time calculation of power generation load of a multi-stage heating extraction steam turbine unit according to an embodiment of the present invention;

[0082] Figure 2 This is a flowchart of the pressure calculation model for the flow path of a heating unit provided in an embodiment of the present invention;

[0083] Figure 3 This is a flowchart of the calculation of the thermodynamic calculation model of the regenerating system of the heating unit according to an embodiment of the present invention;

[0084] Figure 4 This is a flowchart of the complete iterative algorithm calculation for a heating unit according to an embodiment of the present invention;

[0085] Figure 5 This is a data diagram required for the design of the real-time calculation method for the power generation load of a multi-stage heating extraction steam turbine unit according to Embodiment 1 of the present invention.

[0086] Figure 6 This is a data graph calculated by the complete iterative algorithm of the heating unit provided in Embodiment 1 of the present invention. Detailed Implementation

[0087] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0088] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0089] This invention provides a method for real-time calculation of power generation load of a multi-stage heating extraction steam turbine unit, the process of which is as follows: Figure 1 As shown, it includes:

[0090] S1. Based on the heat balance diagram of the heating unit under different operating conditions, the steam extraction data of each section of the unit is fitted with a formula, and the outlet flow data of each section is obtained in sequence to realize the preliminary mathematical expression of the regenerative system.

[0091] The design condition is set as 100% THA (Total Heat Amount) without steam extraction for heating. Combining the heat balance diagrams of the heating unit under different operating conditions, the mathematical relationships are obtained as follows: (The ratio of main steam flow rate data to the main steam flow rate data under the design condition, the extraction steam rate data for each section of the heating unit's heat balance diagram, and the outlet flow rate data for each section.)

[0092] G i，1 =G i-1，1 -G e，i =G i-1，1 -(ax 6 +bx 5 +cx 4 +dx 3 +ex 2 +fx+g); (1)

[0093] The formulas for calculating the steam extraction volume data for each section of the unit are as follows:

[0094] G e，i =ax 6 +bx 5 +cx 4 +dx 3 +ex 2 +fx+g; (2)

[0095] The ratio of the main steam flow rate data to the main steam flow rate data under design conditions is:

[0096]

[0097] In the formula, G i，1 G i-1，1 These represent the current and previous export flow rates, respectively, in kg / s; G e，iThis represents the extraction steam flow rate data for each section of the unit, in kg / s, where a, b, c, d, e, f, and g are determined by the heat balance diagram of the heating unit under different operating conditions; x represents the ratio of the main steam flow rate to the main steam flow rate data under design operating conditions; G 0，1 G0 and G0 represent the main steam flow rate data under variable operating conditions and design operating conditions, respectively, in kg / s, i = 1, 2, 3, 4, 5, 6, 7, 8.

[0098] S2. Based on the structural characteristics of the unit's extraction steam outlet distribution, the turbine is divided into sections. The pressure of the turbine's flow path is calibrated based on the mathematical expression of the extraction steam outlet flow data, and the extraction steam pressure data of each section is obtained.

[0099] Steam turbines are divided into high-pressure cylinders, intermediate-pressure cylinders, and low-pressure cylinders according to their working pressure. The working part of the steam turbine is divided into sections by combining the extraction ports of each regenerating system. A mathematical model for thermodynamic calculation under variable operating conditions is established to achieve pressure calibration of the steam turbine's flow path.

[0100] Based on the approximate proportional relationship between flow rate and pressure in the flow path, the calculation formula for obtaining the extraction steam pressure data of each section during turbine operation under varying conditions is as follows:

[0101]

[0102] In the formula, P e，i P i These represent the extraction steam pressure data for each section under varying operating conditions and design operating conditions, in bar; G i，1 G i The values ​​represent the steam extraction port flow rates for each section under varying operating conditions and design operating conditions, in kg / s; i = 1, 2, 3, 4, 5, 6, 7, 8.

[0103] S3. Obtain the enthalpy data of each extraction steam section using the isentropic enthalpy drop theory in the simplified variable operating condition thermodynamic calculation method, and obtain the extraction steam temperature data of each section by calling the steam property function. Establish a pressure calculation model for the flow path of the heating unit. The calculation process of the pressure calculation model for the flow path is as follows: Figure 2 As shown.

[0104] Given the main steam pressure and temperature data, the main steam enthalpy data H is obtained through the steam property function. 0，1 With the main steam entropy data S 0，1 For a section of extraction steam pressure data P e，1 By combining the theory of isentropic enthalpy drop, a range of isentropic outlet specific enthalpy data h is obtained. j，1 Calculate a segment of extraction enthalpy data.

[0105] The formula for calculating a segment of extraction enthalpy data is as follows:

[0106] H e，1 =H 0，1 -(H0，1 -h j，1 )×j1; (5)

[0107] In the formula, H e，1 This represents a range of extraction enthalpy data, in kJ / kg; H 0，1 This represents the main steam enthalpy data, in kJ / kg; h j，1 j1 represents a segment of isentropic outlet enthalpy data, kJ / kg; j1 represents a segment of relative internal efficiency.

[0108] The extraction steam pressure and enthalpy data for this section are used to obtain the outlet entropy data for this section through steam property functions. These two data points then serve as the inlet parameters for the next extraction section, and the extraction parameters for the next section are calculated sequentially.

[0109] The calculation formula for obtaining the enthalpy data of each extraction segment is as follows:

[0110] H e，i =H e，i-1 -(H e，i-1 -h j，i )×j i (6)

[0111] In the formula, H e，i This represents the enthalpy data of each extraction stage, in kJ / kg; H. e，i-1 This represents the inlet enthalpy data for each segment, i.e., the enthalpy data of the previous extraction steam segment, in kJ / kg; h j，i This represents the isentropic outlet enthalpy data for each segment, in kJ / kg; j i Let i represent the relative internal efficiency of each segment, i = 1, 2, 3, 4, 5, 6, 7, 8.

[0112] S4. Based on the steam extraction pressure data of each section of the heating unit's flow path pressure calculation model and the upper and lower end difference data of each level of heater in the heating unit's heat balance diagram, obtain the enthalpy data of condensate and condensate at the outlet of each level of heater through the steam property function.

[0113] Condensate pressure data at the outlet of each heater (p) w，i Compared with the inlet condensate pressure data p w，i+1 There is a certain pressure loss, which is determined based on the heat balance diagram of the heating unit.

[0114] The calculation formula for obtaining the condensate pressure data of each stage of the heater is as follows:

[0115] p d，i =P e，i ×(1-a); (7)

[0116] In the formula, P d，i This indicates the condensate pressure data for each stage of the heater, in bar; Pe，i The value represents the extraction steam pressure data of each section obtained from the pressure calculation model of the flow path of the heating unit, in bar; a represents the pressure loss of each stage of the heater, which is about 2%-3%, i = 1, 2, 3, 4, 5, 6, 7, 8.

[0117] The saturated temperature data corresponding to the condensate pressure data of each stage of the heater are obtained by using the water vapor property function, and the condensate temperature data of each stage of the heater outlet are obtained.

[0118] The calculation formula for obtaining the condensate temperature data at the outlet of each heater stage is as follows:

[0119] t w，i =t b，i -f i，s (8)

[0120] In the formula, t w，i This indicates the condensate temperature data at the outlet of each heater stage, in °C; t b , i represents the saturation temperature data corresponding to the condensate pressure data of each heater stage, in °C; f i，s This represents the top-end difference data for each heater level, in °C, where i = 1, 2, 3, 4, 5, 6, 7, 8.

[0121] The calculation formula for obtaining the condensate temperature data of each stage of the heater is as follows:

[0122] t d，i =t w，i+1 +f i，x (9)

[0123] In the formula, t d，i This indicates the condensate temperature data for each stage of the heater, in °C; t w，i+1 This represents the condensate temperature data at the inlet of each stage of the heater, i.e., the condensate temperature data at the outlet of the next stage heater, in °C; f i，x This represents the lower end difference data of each heater level, in °C, i = 1, 2, 3, 4, 5, 6, 7, 8.

[0124] The enthalpy data h of the condensate inlet and outlet of each heater were obtained by using water vapor property functions to obtain the enthalpy data h of the condensate inlet of each heater. w，i+1 Enthalpy data of outlet condensate h w，i and hydrophobic enthalpy data h d，i .

[0125] S5. By using the mass conservation equation, energy conservation equation and heat transfer process model of the heater in the regenerative system, obtain the heat balance equation and heat exchange process characteristics of each heater unit.

[0126] In a regenerative system, each stage of the heaters primarily utilizes a portion of the steam extracted from the turbine to heat the boiler feedwater or condensate, achieving regenerative heating. During this process, each stage of the heaters follows the law of conservation of energy; the total energy released by the steam due to condensation from the heater inlet to the outlet is equal to the total energy absorbed by the condensate due to heating in the corresponding process.

[0127] The heat balance equations for each stage of the heater unit in the regenerative system are as follows:

[0128] G e，i H e，i +G x h w，i+1 +G d，i-1 h d，i-1 =G x h w，i +G d，i h d，i (10)

[0129] Among them, G e，i +G d，i-1 =G d，i G e，i This indicates the steam extraction rate data for each stage of the heater, in kg / s; H. e，i This represents the enthalpy data of steam extraction from each stage of the heater, in kJ / kg; G x This represents the condensate flow rate data at the inlet and outlet of each stage of the heater, in kg / s. When i = 1, 2, 3, the G in the high-pressure heater... x =G 0，1 The boiler feedwater flow rate is approximately equal to the turbine main steam flow rate; when i = 5, 6, 7, 8, G in the low-pressure heater... x =G 0，2 This is condensate flow rate data. h w，i h w，i+1 These represent the enthalpy values ​​of condensate at the outlet and inlet of each heater stage, in kJ / kg; G d，i-1 This indicates the condensate flow rate of the previous stage heater, in kg / s; h. d，i-1 This represents the enthalpy of the condensate from the previous stage heater, in kJ / kg; G d，i This indicates the condensate flow rate data for each stage of the heater, in kg / s and h. d，i The data represent the hydrophobic enthalpy values ​​of each heater stage, in kJ / kg, where i = 1, 2, 3, 4, 5, 6, 7, 8.

[0130] In addition, the No. 4 deaerator is designed as a mixing heater. The mixing heater transfers heat and removes oxygen by directly mixing steam extracted from the turbine with water. All the water is mixed with the steam during the heating process and flows out after reaching saturation. No condensate that needs to be discharged separately is generated in this process.

[0131] The heat balance equation for deaerator unit #4 in the regenerative system is as follows:

[0132] G e，c H e，4 +G 0，2 h w，5 +G d，3 h d，3 =G 0，1 h w，4 (11)

[0133] Among them: G e，c +G 0，2 +G d，3 =G 0，1 G e，c This indicates the deaerator extraction steam rate, in kg / s; H₂ e，4 This represents the enthalpy data of deaerator extraction steam, in kJ / kg; G 0，1 This represents the boiler feedwater flow rate, approximating the turbine main steam flow rate, in kg / s; G 0，2 This represents condensate flow rate data, in kg / s; h. w，4 h w，5 These represent the enthalpy values ​​of condensate at the deaerator outlet and inlet, respectively, in kJ / kg; G d，3 This indicates the condensate flow rate of high-pressure heater #3, in kg / s and h. d，3 This represents the enthalpy value of the condensate draining from the #3 high-pressure heater, in kJ / kg.

[0134] S6. Based on the heat balance equations of each heater unit, obtain the steam extraction data for each section on the turbine side and establish a thermodynamic calculation model for the regenerative system. The calculation process of the thermodynamic calculation model for the regenerative system is as follows: Figure 3 As shown.

[0135] After processing the heat balance equations of each heater unit, the steam extraction data of each section on the turbine side are obtained.

[0136] The calculation formula for obtaining the extraction steam volume data of each stage heater corresponding to each section of the turbine side is as follows:

[0137] G e，i =(G x (h w，i -h w，i+1 )+G d，i-1 (h d，i -h d，i-1 )) / (H e，i -h d，i (12)

[0138] In the formula, G e，i This indicates the steam extraction rate data for each stage of the heater, in kg / s; G xThis represents the condensate flow rate data at the inlet and outlet of each stage of the heater, in kg / s. When i = 1, 2, 3, the G in the high-pressure heater... x =G 0.1 The boiler feedwater flow rate is approximately equal to the turbine main steam flow rate; when i = 5, 6, 7, 8, G in the low-pressure heater... x =G 0，2 This is condensate flow rate data. h w，i h w，i+1 These represent the enthalpy values ​​of condensate at the outlet and inlet of each heater stage, in kJ / kg; G d，i-1 This indicates the condensate flow rate of the previous stage heater, in kg / s; h. d，i h d，i-1 These represent the enthalpy values ​​of the condensate from each stage of the heater and the enthalpy value of the condensate from the previous stage heater, respectively, in kJ / kg; H e，i The data represents the steam extraction enthalpy values ​​of each heater stage, in kJ / kg, where i = 1, 2, 3, 4, 5, 6, 7, 8.

[0139] The calculation formula for obtaining the extraction steam volume data of the turbine side corresponding to Deaerator #4 is as follows:

[0140] G e，c =(G 0，1 (h w，4 -h w，5 )+G d，3 (h w，5 -h d，3 )) / (H e，4 -h w，5 (13)

[0141] In the formula, G e，c This indicates the deaerator extraction steam rate, expressed in kg / s; G 0，1 This represents the boiler feedwater flow rate, approximating the turbine main steam flow rate, in kg / s; h. w，4 h w，5 These represent the enthalpy values ​​of condensate at the deaerator outlet and inlet, respectively, in kJ / kg; G d，3 This indicates the condensate flow rate of high-pressure heater #3, in kg / s and h. d，3 This represents the enthalpy of the condensate from the #3 high-pressure heater, in kJ / kg; H e，4 This represents the enthalpy value of the deaerator extraction steam, in kJ / kg.

[0142] S7. Based on the highly coupled mechanism between the flow path pressure calculation model and the regenerative system thermodynamic calculation model, the pressure of the flow path of the heating unit is corrected using the returned data from the regenerative system thermodynamic calculation model. The steam extraction data of each section on the turbine side is replaced with the regenerative system thermodynamic calculation data to form a complete iterative algorithm for the heating unit. The calculation process of the complete iterative algorithm for the heating unit is as follows: Figure 4As shown.

[0143] The extraction steam volume data for each stage of the turbine side corresponding to each heater obtained from the thermodynamic calculation model of the regenerative system of the heating unit is used to replace the extraction steam volume data for each stage of the unit in the pressure calculation model of the flow path, which is based on the heat balance diagram fitted under different operating conditions. According to G i，1 =G i-1，1 -G e，i The outlet flow data of each section on the turbine side were re-obtained. Based on the approximate proportional relationship between flow rate and pressure in the flow path, the extraction steam pressure data of each section during turbine operation under varying conditions were obtained. Then, the enthalpy and temperature data of the extraction steam in each section were obtained by applying the isentropic enthalpy drop theory and calling the steam property function. Based on the re-obtained set of extraction steam parameter data of each section on the turbine side using the pressure calculation model of the flow path of the heating unit, the heat balance equations of each stage of the heater unit were re-established by applying the steam property function and the mass-energy conservation equation and heat transfer process model of the heater in the regenerative system, resulting in new extraction steam flow data of each stage of the heater corresponding to each section on the turbine side.

[0144] Through repeated substitution and iteration of the data returned by the flow path pressure calculation model and the regenerative system thermodynamic calculation model, a complete iterative algorithm for the heating unit is formed. Specifically, the output data of the flow path pressure calculation model is used as the input value of the regenerative system thermodynamic calculation model to calculate the extraction steam volume data for each section on the turbine side. The extraction steam volume data obtained from the regenerative system thermodynamic calculation model is used as the input value of the flow path pressure calculation model to calculate and solve for data such as extraction steam pressure and enthalpy for each section. This ultimately forms a complete iterative algorithm for the heating unit where the flow path pressure calculation model uses the extraction steam volume data to solve for extraction steam pressure and other data, and the regenerative system thermodynamic calculation model uses the extraction steam pressure and other data to solve for extraction steam volume data.

[0145] S8. The real-time power generation load of the heating unit is obtained through iterative calculations of the pressure calculation model of the steam turbine's flow path and the thermodynamic calculation model of the regenerator system, as well as the calculation of the unit efficiency.

[0146] Based on the complete iterative algorithm for heating units, the iterative algorithm ends when the steam extraction volume data of each stage of the heater corresponding to each section of the turbine side in the thermodynamic calculation model of the regenerative system are approximately equal to the steam extraction volume data of the next set of corresponding sections. The algorithm outputs the final data of the steam extraction port flow rate and the steam extraction enthalpy value of each section of the unit, which are used to calculate the real-time power generation load of the heating unit and analyze the unit performance.

[0147] The formula for calculating the power generation capacity of the high-pressure cylinder on the turbine side of the heating unit is as follows:

[0148] N HP =G 0，1 (H 0，1 -H e，1 )+G 1，1 (He，1 -H e，2 (14)

[0149] The formula for calculating the power generation capacity of the intermediate-pressure cylinder on the turbine side of the heating unit is as follows:

[0150] N IP =G 2，1 (H z，1 -H e，3 )+G 3，1 (H e，3 -H e，4 (15)

[0151] The formula for calculating the power generation capacity of the low-pressure cylinder on the turbine side of the heating unit is as follows:

[0152] N LP =G 4，1 (H e，4 -H e，5 )+G 5，1 (H e，5 -H e，6 )+G 6，1 (H e，6 -H e，7 )+G 7，1 (H e，7 -H e，8 )+G 8，1 (H e，8 -H e，9 (16)

[0153] The formula for calculating the real-time power generation load on the turbine side of the heating unit is as follows:

[0154] N=(N HP +N IP +N LP )×η; (17)

[0155] In the formula, N represents the real-time power generation load on the turbine side of the heating unit, in MW; N HP N IP N LP These represent the real-time power generation loads (MW) of the high-pressure, intermediate-pressure, and low-pressure cylinders on the turbine side of the heating unit; G 01 This represents the main steam flow rate of the steam turbine, in kg / s; G i1 This represents the outlet flow rate data for each section of the steam turbine, in kg / s; H. 01 This represents the enthalpy of the main steam in the steam turbine, in kJ / kg; H ei This represents the enthalpy data of steam extraction from each stage of the heater, in kJ / kg; H. z1 This represents the enthalpy of the steam entering the intermediate pressure cylinder, in kJ / kg; H e9The value represents the enthalpy of the exhaust steam on the turbine side, kJ / kg; η = 0.982 represents the generator power, i = 1, 2, 3, 4, 5, 6, 7, 8.

[0156] Furthermore, the unit efficiency, i.e., the relative internal efficiency of each section of the unit, has already been considered during the segmented calculation of the steam extraction enthalpy data on the turbine side. The extraction enthalpy data for each section of the unit is known from the heat balance diagram under different operating conditions. Based on the extraction pressure data and inlet entropy data for each section, the isentropic outlet specific enthalpy data is obtained through the steam property function, and the unit efficiency is then calculated backwards.

[0157]

[0158] In the formula, j i H represents the relative internal efficiency of each section of the unit; e，i This represents the enthalpy data of each extraction stage, in kJ / kg; H. e，i-1 This represents the inlet enthalpy data for each segment, i.e., the enthalpy data of the previous extraction steam segment, in kJ / kg; h j，i The values ​​represent the isentropic outlet enthalpy data for each segment, in kJ / kg, where i = 1, 2, 3, 4, 5, 6, 7, 8.

[0159] The relative internal efficiency data of each segment in the heat balance diagram of the existing heating unit under different operating conditions are calculated. A formula is then fitted using the ratio of the main steam flow rate data to the main steam flow rate data under the design operating conditions to obtain a formula applicable to all operating conditions of the unit, j. i =hx 6 +ix 5 +jx 4 +kx 3 +lx 2 Formulas for calculating the relative internal efficiency of each segment of +mx+n.

[0160] The real-time calculation method for the power generation load of a multi-stage heating extraction turbine unit provided in this invention performs formula fitting on the extraction steam volume data of each section of the unit, calculates the outlet flow rate data of each section, and obtains the extraction steam parameter data of each section on the turbine side of the heating unit through a simplified variable operating condition thermodynamic calculation method of the turbine and the work process of energy conversion within the stage, and establishes a pressure calculation model for the flow path of the heating unit. Secondly, combined with the mass conservation equation, energy conservation equation and heat transfer process model of the heater in the regenerative system, the heat balance equation and heat exchange process characteristics of each stage heater unit are obtained, and a thermodynamic calculation model of the regenerative system is established to calculate the extraction steam volume data of each section on the turbine side of the unit. Finally, based on the high coupling mechanism between the pressure calculation model of the flow path and the thermodynamic calculation model of the regenerative system, the pressure of the flow path of the heating unit is corrected using the returned data of the thermodynamic calculation model of the regenerative system, forming a complete iterative algorithm for the heating unit, and finally obtaining the real-time power generation load of the heating unit. This invention can be used for real-time power generation load calculation and performance analysis of heating units, which helps to coordinate the power generation output guarantee and the safety of heating and steam supply of heating units, and is of great significance for the safe operation of steam turbines.

[0161] The following description uses specific examples to illustrate the point.

[0162] Example 1

[0163] Step 1: Establish a pressure calculation model for the flow path of the heating unit.

[0164] The THA working condition is selected as the design working condition for the model. The data required for the design working condition are as follows: Figure 5 As shown. The selected example uses the main steam flow rate G. 0，1 The steam flow rate is 545 kg / s, and the main steam pressure is P. 0，1 The main steam temperature is 242 bar, and the main steam temperature is T. 0，1 The temperature is 566℃, and the steam extraction temperature for medium-pressure heating is G. r1 The steam extraction rate for low-pressure heating is 27.78 kg / s. zr1 It is 166.67 kg / s.

[0165] The ratio x of the main steam flow rate data under the operating condition in Example 1 to the main steam flow rate data under the design condition:

[0166]

[0167] Combining the steam extraction data G of each section in the heat balance diagram of the heating unit under different operating conditions e，i Then, perform formula fitting.

[0168] Calculate the extraction steam flow rate G under the operating conditions of the example. e，1 The calculation formula is:

[0169] G e，1 =67.8208x 6-197.1564x 5 +170.2653x 4 -52.4389x 2 +47.8506x-4.6912; (20)

[0170] Calculate the extraction steam flow rate G under the operating conditions of the example. e，1 :

[0171] G e，1 =67.8208×(1.1553) 6 -197.1564×(1.1553) 5 +170.2653×(1.1553) 4 -52.4389×(1.1553) 2 +47.8506×(1.1553)-4.6912=39.41(kg / s); (21)

[0172] Obtain the outlet flow rate data for the example operating condition and the design operating condition:

[0173] G1 = G0 - G c，1 =471.75-31.65=440.1(kg / s); (22)

[0174] G 1，1 =G 0，1 -G e，1 =545-39.41=505.59(kg / s); (23)

[0175] Based on the approximate proportional relationship between flow rate and pressure in the flow path, the extraction steam pressure data P of the first stage under the operating conditions of the embodiment was obtained. e，1 :

[0176]

[0177] Based on the main steam pressure P 0，1 242 bar and main steam temperature T 0，1 The main steam enthalpy data H was obtained by calling the PT function in the steam property function for 566℃. 0，1 With the main steam entropy data S 0，1 :

[0178] H 0，1 =pt(P 0，1 T 0，1 (25) = 3396.02 (kJ / kg);

[0179] S 0，1 =pt(P 0，1 T 0，1(26) = 6.264;

[0180] For a section of extraction steam pressure data P e，1 Combining the isentropic enthalpy drop theory in the simplified variable-condition thermodynamic calculation method, the isentropic outlet specific enthalpy data h are obtained by calling the PS function in the water vapor property function. j，1 :

[0181] h j，1 =ps(P e，1 S 0，1 = 3058.55 (kJ / kg); (27)

[0182] Calculate a segment of extraction enthalpy data H e，1 :

[0183] H e，1 =H 0，1 -(H 0，1 -h j，1 )×j1=3396.02-(3396.02-3058.55)×0.8717=3101.85(kJ / kg); (28)

[0184] The extraction steam temperature data T is obtained by calling the pH function in the water vapor property function. e，1 :

[0185] T e，1 =ph(P e，1 H e，1 (29) = 384.046 (℃);

[0186] The PT function in the steam property function is used to obtain a segment of extraction steam entropy data S. e，1 :

[0187] S e，1 =pt(P e，1 T e，1 (30) = 6.329;

[0188] At this time, a section of extraction steam parameter data (a section of extraction steam pressure data P) e，1 A section of extraction steam temperature data T e，1 A section of extraction enthalpy data H e，1 A segment of steam extraction entropy data S e，1 The parameters are used as the inlet parameters for the second stage to calculate the extraction parameters for the second stage, and the extraction parameters for each stage are obtained sequentially.

[0189] Among them, the steam extraction volume data G for each section e，i Same as step 1 for solving the extraction steam flow rate G. e，1 The calculation formula is similar:

[0190] Ge，i =ax 6 +bx 5 +cx 4 +dx 3 +ex 2 +fx+g;(31)

[0191] Obtain the outlet flow data for each section under the implementation example operating condition and the design operating condition:

[0192] G i =G i-1 -G ci (32)

[0193] G i1 =G i-1，1 -G ei (33)

[0194] In Example 1, when calculating the outlet flow rates of the second and fourth stages, the data of the steam extraction for medium-pressure heating and the data of the steam extraction for low-pressure heating are subtracted respectively.

[0195] Calculate the extraction steam pressure data P for each section of the operating condition in the example. e，i :

[0196]

[0197] Calculate the isentropic outlet specific enthalpy data h for each section of the operating condition in the example. j，i :

[0198] h j，i =ps(P e，i S e，i-1 (35)

[0199] Calculate the extraction enthalpy data H of each stage of the embodiment's operating conditions. e，i :

[0200] H e，i =H e，i-1 -(H e，i-1 -h j，i )×j i (36)

[0201] Calculate the extraction steam temperature data T for each section under the operating conditions of the embodiment. e，i and the entropy data of each extraction section S e，i :

[0202] T e，i =ph(P e，i H e，i (37)

[0203] S e，i =pt(P e，i T e，i(38)

[0204] i=1, 2, 3, 4, 5, 6, 7, 8.

[0205] Step 2: Establish a thermodynamic calculation model for the regenerative system.

[0206] Known condensate pressure data p at the outlet of each stage of the heater in the embodiment operating condition w，i Compared with the inlet condensate pressure data p w，i+1 There is a certain pressure loss of approximately 0.2%. Furthermore, the pressure difference data between the upper and lower ends of each heater stage is known. For example, the pressure difference at the upper end of the #1 high-pressure heater is f. 1，s = -1.7℃, with a lower end difference of f 1，x =5.6℃; the temperature difference at the upper end of the No. 2 high-pressure heater is f 2，s =0℃, the difference at the lower end is f 2，x =5.6℃.

[0207] Obtain the condensate pressure data p at the outlet of high-pressure heater #1 w，1 The calculation formula is:

[0208]

[0209] In this embodiment, the boiler-side system is reasonably simplified. Based on the heat balance diagram of the heating unit, the pressure loss b between the boiler feedwater pressure (i.e., the condensate pressure at the outlet of the No. 1 high-pressure heater) and the main steam pressure is determined to be approximately 13.86%.

[0210] Obtain the condensate pressure data p at the outlet of the No. 2 high-pressure heater. w，2 :

[0211]

[0212] Obtain the condensate pressure data p of high-pressure heater #1 d 1:

[0213] p d，1 =P e，1 ×(1-a)=76.66×0.971=74.44(bar); (41)

[0214] The saturation temperature data t corresponding to the condensate pressure data of each stage of the heater is obtained by calling the TSK function in the water vapor property function. b，i Obtain condensate temperature data t at the outlet of each heater. w，i .

[0215] Among them, the condensate temperature data t at the outlet of the No. 1 high-pressure heater was obtained. w，1 :

[0216] t b，1 =tsk(p d，1(42) = 280.98 (℃);

[0217] t w，1 =t b，1 -f 1，s =289.98-(-1.7)=291.68(℃); (43)

[0218] Similarly, obtain the condensate temperature data t at the outlet of the #2 high-pressure heater. w，2 =257.8℃.

[0219] Obtain the condensate temperature data t of the No. 1 high-pressure heater. d，1 :

[0220] t d，1 =t w，2 +f 1，x =257.8 + 5.6 = 263.4 (℃); (44)

[0221] The condensate and condensate parameters at the inlet and outlet of the #1 high-pressure heater were obtained by calling the PT function in the water vapor property function to retrieve the enthalpy data h of the condensate at the inlet of the #1 high-pressure heater. w 2. Enthalpy data of outlet condensate h w，1 and hydrophobic enthalpy data h a，1 :

[0222] h w，1 =pt(p w，1 , t w，1 (45) = 1286.96 (kJ / kg);

[0223] h w，2 =pt(p w，2 , t w，2 = 1124.08 (kJ / kg); (46)

[0224] h d，1 =pt(p d，1 , t d，1 = 1151.34 (kJ / kg); (47)

[0225] The heat balance equation for unit #1 high-pressure heater is obtained by using the mass conservation equation, energy conservation equation, and heat transfer process model of the heater in the regenerative system:

[0226] G e，1 H e，1 +G 0，1 h w，2 =G 0，1 h w，1 +G d，1 h d，1 (48)

[0227] Among them: G e，1 =G d，1 ;

[0228] The formula for calculating the extraction steam volume data of the turbine side using the heat balance equation is as follows:

[0229]

[0230] The calculation process for the remaining heaters is the same as in step 2, where the steam extraction data for each section of the turbine side is obtained using the heat balance equation.

[0231] Step 3: Form a complete iterative algorithm for the heating unit.

[0232] In step 2, the steam extraction data of each stage of the heaters corresponding to each section of the turbine side obtained from the thermodynamic calculation model of the regenerative system are used to replace the steam extraction data of each section of the unit in step 1, which is based on the heat balance diagram fitted under different operating conditions, to solve for the extraction pressure, enthalpy, and other data of each section. The output data of the pressure calculation model of the flow path in step 1 is used as the input value of the thermodynamic calculation model of the regenerative system in step 2 to calculate the steam extraction data of each section of the turbine side. Through repeated replacement and iteration of the data returned by the pressure calculation model of the flow path and the thermodynamic calculation model of the regenerative system, a complete iterative algorithm for the heating unit is formed.

[0233] The data obtained by the complete iterative algorithm for the heating unit (data related to solving the real-time power generation load of the heating unit) is as follows: Figure 6 As shown.

[0234] Step 4: Calculate the real-time power generation load of the heating unit.

[0235] The formula for calculating the power generation capacity of the high-pressure cylinder on the turbine side of the heating unit is as follows:

[0236] N HP =G 0，1 (H 0，1 -H e，1 )+G 1，1 (H e，1 -H e，2 )

[0237] = (545 × (3396.02 - 3101.8) + 503.2 × (3101.8 - 2994.4)) × 0.001

[0238] =214.39 (MW); (50)

[0239] The formula for calculating the power generation capacity of the intermediate-pressure cylinder on the turbine side of the heating unit is as follows:

[0240] N IP =G2，1 (H z，1 -H e，3 )+G 3，1 (H e，3 -H e，4 )=(425.708×(3595.1-3387.8)+401.098×(3387.8-3162.5))×0.001=178.62(MW); (51)

[0241] The formula for calculating the power generation capacity of the low-pressure cylinder on the turbine side of the heating unit is as follows:

[0242] N LP =G 4，1 (H e，4 -H e，5 )+G 5，1 (H e，5 -H e，6 )+G 6，1 (H e，6 -H e，7 )+G 7，1 (H e，7 -H e，8 )+G 8，1 (H e，8 -H e，9 )=(165.703×(3162.5-2984.3)+153.307×(2984.3-2763.4)+141.74×(2763.4-264 3.9)+131.578×(2643.9-2541.6)+116.304×(2541.6-2409))*0.001=109.214(MW); (52)

[0243] The formula for calculating the real-time power generation load on the turbine side of the heating unit is as follows:

[0244] N=(N HP +N IP +N LP )×η=(214.39+178.62+109.214)×0.982=493.184(MW); (53)

[0245] Given that the actual operating power generation load in this embodiment is 488.97MW, the error is approximately 0.854%.

[0246] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0247] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0248] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for real-time calculation of power generation load of a multi-stage heating extraction steam turbine unit, characterized in that, Includes the following steps: S1. Based on the heat balance diagram of the heating unit under different operating conditions, the steam extraction data of each section of the heating unit is fitted with a formula to obtain the outlet flow data of each section and to obtain the mathematical expression of the regenerative system. S2. Based on the structural characteristics of the steam extraction port distribution of the heating unit, the unit is divided into sections. The pressure of the turbine flow passage is calibrated based on the mathematical expression of the steam extraction port flow data, and the steam extraction pressure data of each section is obtained. S3. Using the isentropic enthalpy drop theory in the simplified variable operating condition thermodynamic calculation method, obtain the enthalpy data of each section of extraction steam, call the steam property function to obtain the temperature data of each section of extraction steam, and establish a pressure calculation model for the flow path of the heating unit. S4. Based on the pressure calculation model of the flow path of the heating unit, the extraction steam pressure data of each section and the upper and lower end difference data of each level of heater in the heat balance diagram of the heating unit are obtained. The enthalpy data of condensate and condensate at the outlet of each level of heater are obtained through the steam property function. S5. By using the mass conservation equation, energy conservation equation and heat transfer process model of the heater in the regenerative system, obtain the heat balance equation and heat exchange process characteristics of each heater unit. S6. Based on the heat balance equations of each heater unit, obtain the steam extraction data of each section on the turbine side and establish a thermodynamic calculation model of the regenerative system. S7. Based on the highly coupled mechanism of the pressure calculation model of the flow path and the thermodynamic calculation model of the regenerating system, the return data of the thermodynamic calculation model of the regenerating system is used to correct the pressure of the flow path of the heating unit, and the thermodynamic calculation data of the regenerating system is used to replace the steam extraction data of each section on the turbine side to form a cyclic iterative algorithm for the heating unit. Through repeated substitution and iteration of the data returned by the flow path pressure calculation model and the regenerative system thermodynamic calculation model, a cyclic iterative algorithm for the heating unit is formed. That is, the output data of the flow path pressure calculation model is used as the input value of the regenerative system thermodynamic calculation model to calculate the steam extraction volume data of each section on the turbine side, and the steam extraction volume data of each section obtained by the regenerative system thermodynamic calculation model is used as the input value of the flow path pressure calculation model to calculate and solve for the steam extraction pressure and enthalpy data of each section. This forms a cyclic iterative algorithm for the heating unit that uses the flow path pressure calculation model to solve for the steam extraction pressure data and the regenerative system thermodynamic calculation model to solve for the steam extraction volume data using the steam extraction pressure data. S8. The real-time power generation load of the heating unit is obtained by iterative calculation of the pressure calculation model of the steam turbine flow path and the thermodynamic calculation model of the regenerating system, as well as the calculation of the unit efficiency.

2. The method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units according to claim 1, characterized in that, Step S1 is as follows: The design condition is set as 100% THA (Total Heat Amount) without steam extraction for heating. Combining the heat balance diagrams of the heating unit under different operating conditions, the mathematical relationships are obtained as follows: (The ratio of main steam flow rate data to the main steam flow rate data under the design condition, the extraction steam rate data for each segment in the heat balance diagram of the heating unit, and the outlet flow rate data for each segment.) G i,1 =G i-1,1 -G e,i =G i-1,1 -(ax 6 +bx 5 +cx 4 +dx 3 +ex 2 +fx+g); The formula for calculating the steam extraction volume of each section of the heating unit is as follows: G e,i =ax 6 +bx 5 +cx 4 +dx 3 +ex 2 +fx+g; The ratio of the main steam flow rate data to the main steam flow rate data under design conditions is: In the formula, G i,1 G i-1,1 These represent the current and previous export flow rates, respectively, in kg / s; G e,i This represents the extraction steam flow rate data for each section of the unit, in kg / s, where a, b, c, d, e, f, and g are determined by the heat balance diagram of the heating unit under different operating conditions; x represents the ratio of the main steam flow rate to the main steam flow rate data under design operating conditions; G 0,1 G0 and G0 represent the main steam flow rate data under variable operating conditions and design operating conditions, respectively, in kg / s, i = 1, 2, 3, 4, 5, 6, 7, 8.

3. The method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units according to claim 1, characterized in that, Step S2 is as follows: The steam turbine is divided into high-pressure, intermediate-pressure, and low-pressure cylinders according to its operating pressure. The power-generating section of the turbine is further segmented by incorporating the extraction ports of each regenerative system. A variable-condition thermodynamic calculation mathematical model is established to calibrate the pressure of the turbine's flow path. Based on the approximate proportional relationship between flow rate and pressure in the flow path, the calculation formula for the extraction pressure data of each section during variable-condition operation of the steam turbine is as follows: In the formula, P e,i P i These represent the extraction steam pressure data for each section under varying operating conditions and design operating conditions, in bar; G i,1 G i These represent the flow rates at each extraction port under varying and design operating conditions, in kg / s, with i = 1, 2, 3, 4, 5, 6, 7, 8.

4. The method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units according to claim 1, characterized in that, Step S3 is as follows: Given the main steam pressure and temperature data, the main steam enthalpy data H is obtained through the steam property function. 0,1 With the main steam entropy data S 0,1 For a section of extraction steam pressure data P e,1 By combining the theory of isentropic enthalpy drop, a range of isentropic outlet specific enthalpy data h is obtained. j,1 Calculate a segment of extraction steam enthalpy data; the formula for obtaining a segment of extraction steam enthalpy data is: H e,1 =H 0,1 -(H 0,1 -h j,1 )×j1; In the formula, H e,1 This represents a range of extraction enthalpy data, in kJ / kg; H 0,1 This represents the main steam enthalpy data, in kJ / kg; h j,1 j1 represents a segment of isentropic outlet enthalpy data, kJ / kg; j1 represents a segment of relative internal efficiency. The extraction steam pressure and enthalpy data for this section are used to obtain the outlet entropy data for this section through the steam property function. These two data points then serve as the inlet parameters for the next extraction section, and the extraction parameters for the next section are calculated sequentially. The formula for obtaining the enthalpy data for each extraction section is as follows: H e,i =H e,i-1 -(H e,i-1 -h j,i )×j i ; In the formula, H e,i This represents the enthalpy data of each extraction stage, in kJ / kg; H. e,i-1 This represents the inlet enthalpy data for each segment, i.e., the enthalpy data of the previous extraction steam segment, in kJ / kg; h j,i This represents the isentropic outlet enthalpy data for each segment, in kJ / kg; j i Let i represent the relative internal efficiency of each segment, i = 1, 2, 3, 4, 5, 6, 7, 8.

5. The method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units according to claim 1, characterized in that, Step S4 is as follows: Condensate pressure data at the outlet of each heater (p) w,i Compared with the inlet condensate pressure data p w,i+1 Pressure loss exists, determined based on the heating unit's heat balance diagram; the calculation formula for obtaining the drain pressure data of each stage heater is: p d,i =P e,i ×(1-a); In the formula, p d,i This indicates the condensate pressure data for each stage of the heater, in bar; P e,i The value represents the extraction steam pressure data of each section obtained from the pressure calculation model of the flow path of the heating unit, in bar; a represents the pressure loss of each stage of the heater, which is 2%-3%, i = 1, 2, 3, 4, 5, 6, 7, 8; The saturated temperature data corresponding to the condensate pressure data of each stage of the heater are obtained by using the water vapor property function, and the condensate temperature data of each stage of the heater outlet is obtained. The calculation formula for obtaining the condensate temperature data of each stage of the heater outlet is: t w,i =t b,i -f i,s ; In the formula, t w,i This indicates the condensate temperature data at the outlet of each heater stage, in °C. t b,i This represents the saturation temperature data (°C) corresponding to the condensate pressure data of each heater stage; f i,s This represents the top-end difference data for each heater stage, in °C; i = 1, 2, 3, 4, 5, 6, 7, 8; The formula for calculating the condensate temperature data of each stage of the heater is: t d,i =t w,i+1 +f i,x ; In the formula, t d,i This indicates the condensate temperature data for each stage of the heater, in °C; t w,i+1 This represents the condensate temperature data at the inlet of each stage of the heater, i.e., the condensate temperature data at the outlet of the next stage heater, in °C; f i,x This represents the lower-end difference data of each heater stage, in °C; i = 1, 2, 3, 4, 5, 6, 7, 8; The enthalpy data h of the condensate at the inlet and outlet of each heater were obtained by using water vapor property functions to obtain the enthalpy data h of the condensate at the inlet of each heater. w,i+1 Enthalpy data of outlet condensate h w,i and hydrophobic enthalpy data h d,i .

6. The method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units according to claim 1, characterized in that, Step S5 is as follows: In the regenerative system, the heaters at each stage mainly use a portion of the steam extracted from the turbine to heat the boiler feedwater or condensate, thus achieving regenerative heating. During this process, the heaters at each stage follow the law of conservation of energy, and the total energy released by the steam due to condensation from the heater inlet to the outlet is equal to the total energy absorbed by the condensate due to heating in the corresponding process. The heat balance equations for each stage of the heater unit in the regenerative system are as follows: G e,i H e,i +G x h w,i+1 +G d,i-1 h d,i-1 =G x h w,i +G d,i h d,i ; Among them, G e,i +G d,i-1 =G d,i G e,i This indicates the steam extraction rate data for each stage of the heater, in kg / s; H. e,i This represents the enthalpy data of steam extraction from each stage of the heater, in kJ / kg; G x This represents the condensate flow rate data at the inlet and outlet of each stage of the heater, in kg / s; when i = 1, 2, 3, G in the high-pressure heater x =G 0,1 The boiler feedwater flow rate is approximately equal to the turbine main steam flow rate; when i = 5, 6, 7, 8, G in the low-pressure heater... x =G 0,2 For condensate flow rate data; h w,i h w,i+1 These represent the enthalpy values ​​of condensate at the outlet and inlet of each heater stage, in kJ / kg; G d,i-1 This indicates the condensate flow rate of the previous stage heater, in kg / s; h. d,i-1 This represents the enthalpy of the condensate from the previous stage heater, in kJ / kg; G d,i This indicates the condensate flow rate data for each stage of the heater, in kg / s and h. d,i The data represents the hydrophobic enthalpy values ​​of each stage of the heater, in kJ / kg; i = 1, 2, 3, 4, 5, 6, 7, 8; Deaerator #4 is a mixing heater. It uses direct mixing of steam extracted from the turbine with water for heat transfer and deaeration. All water is mixed with steam during the heating process and flows out only after reaching saturation. No condensate requiring separate discharge is generated during this process. The heat balance equation for deaerator #4 in the regenerative system is as follows: G e,c H e,4 +G 0,2 h w,5 +G d,3 h d,3 =G 0,1 h w,4 ; Among them: G e,c +G 0,2 +G d,3 =G 0,1 G e,c This indicates the deaerator extraction steam rate, in kg / s; H₂ e,4 This represents the enthalpy data of deaerator extraction steam, in kJ / kg; G 0,1 This represents the boiler feedwater flow rate, approximating the turbine main steam flow rate, in kg / s; G 0,2 This represents condensate flow rate data, in kg / s; h. w,4 h w,5 These represent the enthalpy values ​​of condensate at the deaerator outlet and inlet, respectively, in kJ / kg; G d,3 This indicates the condensate flow rate of high-pressure heater #3, in kg / s and h. d,3 This represents the enthalpy value of the condensate draining from the #3 high-pressure heater, in kJ / kg.

7. The method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units according to claim 1, characterized in that, Step S6 is as follows: After processing the heat balance equations of each heater unit, the steam extraction rate data for each section on the turbine side are obtained; the calculation formulas for obtaining the steam extraction rate data for each section on the turbine side corresponding to each heater unit are as follows: G e,i =(G x (h w,i -h w,i+1 )+G d,i-1 (h d,i -H d,i-1 )) / (H e,i -h d,i ); In the formula, G e,i This indicates the steam extraction rate data for each stage of the heater, in kg / s; G x This represents the condensate flow rate data at the inlet and outlet of each stage of the heater, in kg / s; when i = 1, 2, 3, G in the high-pressure heater x =G 0,1 The boiler feedwater flow rate is approximately equal to the turbine main steam flow rate; when i = 5, 6, 7, 8, G in the low-pressure heater... x =G 0,2 For condensate flow rate data; h w,i h w,i+1 These represent the enthalpy values ​​of condensate at the outlet and inlet of each heater stage, in kJ / kg; G d,i-1 This indicates the condensate flow rate of the previous stage heater, in kg / s; h. d,i h d,i-1 These represent the enthalpy values ​​of the condensate from each stage of the heater and the enthalpy value of the condensate from the previous stage heater, respectively, in kJ / kg; H e,i This represents the enthalpy data of steam extraction from each stage of the heater, in kJ / kg; i = 1, 2, 3, 4, 5, 6, 7, 8; The formula for calculating the extraction steam volume data of the turbine side corresponding to Deaerator #4 is as follows: G e,c =(G 0,1 (h w,4 -h w,5 )+G d,3 (h w,5 -h d,3 )) / (H e,4 -h w,5 ); In the formula, G e,c This indicates the deaerator extraction steam rate, expressed in kg / s; G 0,1 This represents the boiler feedwater flow rate, approximating the turbine main steam flow rate, in kg / s; h. w,4 h w,5 These represent the enthalpy values ​​of condensate at the deaerator outlet and inlet, respectively, in kJ / kg; G d,3 This indicates the condensate flow rate of high-pressure heater #3, in kg / s and h. d,3 This represents the enthalpy of the condensate from the #3 high-pressure heater, in kJ / kg; H e,4 This represents the enthalpy value of the deaerator extraction steam, in kJ / kg.

8. The method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units according to claim 1, characterized in that, Step S7 is as follows: The extraction steam volume data for each stage of the turbine side corresponding to each heater obtained from the thermodynamic calculation model of the regenerative system of the heating unit is used to replace the extraction steam volume data for each stage of the unit in the pressure calculation model of the flow path, which is based on the heat balance diagram fitted under different operating conditions. According to G i,1 =G i-1,1 -G e,i The outlet flow data of each section on the turbine side were obtained again; Based on the approximate proportional relationship between flow rate and pressure in the flow path, the extraction steam pressure data of each section of the turbine is obtained during variable operating conditions. Then, the enthalpy and temperature data of each extraction section are obtained by using the isentropic enthalpy drop theory and calling the steam property function. Based on the pressure calculation model of the flow path of the heating unit, a set of extraction steam parameters for each section of the turbine side were obtained again. The heat balance equations of each stage of the heater unit were re-established by using the steam property function, the mass-energy conservation equation of the heater in the regenerative system and the heat transfer process model. New extraction steam data for each stage of the heater corresponding to each section of the turbine side were obtained.

9. The method for real-time calculation of power generation load of multi-stage heating extraction steam turbine units according to claim 1, characterized in that, Step S8 is as follows: Based on the cyclic iterative algorithm of the heating unit, when the cyclic calculation continues until the steam extraction volume data of each stage heater corresponding to each section of the turbine side in the previous set of thermodynamic calculation model of the regenerative system is equal to the steam extraction volume data of the next set of corresponding sections, the cyclic iterative algorithm of the heating unit ends and the final data of the steam extraction port flow rate and steam extraction enthalpy value of each section of the unit are output, which are used to calculate the real-time power generation load of the heating unit and analyze the unit performance. The formula for calculating the power generation capacity of the high-pressure cylinder on the turbine side of the heating unit is as follows: N HP =G 0,1 (H 0,1 -H e,1 )+G 1,1 (H e,1 -H e,2 ); The formula for calculating the power generation capacity of the intermediate-pressure cylinder on the turbine side of the heating unit is: N IP =G 2,1 (H z,1 -H e,3 )+G 3,1 (H e,3 -H e,4 ); The formula for calculating the power generation capacity of the low-pressure cylinder on the turbine side of the heating unit is as follows: N LP =G 4,1 (H e,4 -H e,5 )+G 5,1 (H e,5 -H e,6 )+G 6,1 (H e,6 -H e,7 )+G 7,1 (H e,7 -H e,8 )+G 8,1 (H e,8 -H e,9 ); The formula for calculating the real-time power generation load on the turbine side of the heating unit is as follows: N=(N HP +N IP +N LP )×η; Where N represents the real-time power generation load on the turbine side of the heating unit, in MW; N HP N IP N LP These represent the real-time power generation loads (MW) of the high-pressure, intermediate-pressure, and low-pressure cylinders on the turbine side of the heating unit; G 0,1 This represents the main steam flow rate of the steam turbine, in kg / s; G i,1 This represents the outlet flow rate data for each section of the steam turbine, in kg / s; H. 0,1 This represents the enthalpy of the main steam in the steam turbine, in kJ / kg; H e,i This represents the enthalpy data of steam extraction from each stage of the heater, in kJ / kg; H. z,1 This represents the enthalpy of the steam entering the intermediate pressure cylinder, in kJ / kg; H e,9 The data represents the enthalpy of the exhaust steam from the turbine side, in kJ / kg; η = 0.982 represents the generator power; i = 1, 2, 3, 4, 5, 6, 7, 8; In the process of calculating the extraction steam enthalpy data for each section on the turbine side, the unit efficiency, i.e., the relative internal efficiency of each section of the unit, has already been considered. The extraction steam enthalpy data for each section of the unit is known from the heat balance diagram under different operating conditions of the heating unit. Based on the extraction steam pressure data and inlet entropy data for each section, isentropic outlet specific enthalpy data is obtained through water vapor property functions, and the unit efficiency is calculated backwards. In the formula, j i H represents the relative internal efficiency of each section of the unit; e,i This represents the enthalpy data of each extraction stage, in kJ / kg; H. e,i-1 This represents the inlet enthalpy data for each segment, i.e., the enthalpy data of the previous extraction steam segment, in kJ / kg; h j,i Represents the isentropic outlet specific enthalpy data for each segment, kJ / kg; i = 1, 2, 3, 4, 5, 6, 7, 8; The relative internal efficiency data of each segment in the heat balance diagram of the existing heating unit under different operating conditions are calculated. A formula is then fitted using the ratio of the main steam flow rate data to the main steam flow rate data under the design operating conditions to obtain a formula applicable to all operating conditions of the unit, j. i =hx 6 +ix 5 +jx 4 +kx 3 +lx 2 The formula for calculating the relative internal efficiency of each segment of +mx+n.

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