A calculation method and terminal for the operating domain of a condensing unit after steam extraction transformation

Abstract

The present invention discloses a method for calculating the operating domain of a condensing unit after steam extraction transformation, the method comprises obtaining operating data of the condensing unit under rated state, and calculating the unit operating limit line based on the operating data, wherein the unit operating limit line comprises the minimum steam extraction pressure limit line of the transformed unit; according to the determined unit operating limit line, the operating domain of the condensing unit after heat supply transformation is determined; the present invention takes into account the limitation caused by the unit in order to meet the steam extraction pressure requirement under low load conditions, proposes the calculation of the steam extraction pressure limit line, and further determines the operating domain of the condensing unit after heat supply transformation, thus solving the problem of imperfect calculation of the current operating domain of the steam extraction unit and providing a reference basis for the operation of the condensing unit after transformation into the steam extraction unit.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation, and in particular to a calculation method and a terminal for an operating domain of a condensing unit after steam extraction transformation. Background Art

[0002] A series of climate issues such as the greenhouse effect caused by excessive carbon dioxide emissions are major challenges faced by the world. The power sector is an important source of carbon dioxide emissions in my country, with annual emissions of about 4.5 billion tons, accounting for more than 40% of total carbon emissions. In addition, although my country's renewable energy installed capacity and power generation are growing rapidly, coal-fired power still accounts for a considerable proportion, and the power structure is still dominated by thermal power. As a high-emission power source, clean and efficient transformation of coal-fired power is an important part of the long-term sustainable development of coal-fired power.

[0003] The steam supply transformation of pure condensing units can realize the combination of coal-fired power and urban development, and provide energy services for other industrial development and life. The transformation of pure condensing units into steam supply units can utilize the cold end loss of coal-fired power units, improve the economic efficiency of power generation and heating of units, and achieve clean and efficient operation. In the context of clean development of coal-fired power, it is the main trend to make full use of existing resources, implement steam supply transformation of large-capacity units in service, replace backward small coal-fired units with high energy consumption and heavy pollution, and use large units for centralized heating and steam supply.

[0004] After the pure condensing unit is transformed into a steam supply unit, its operating domain needs to be calculated. During the calculation process, it is also necessary to consider whether the extraction steam pressure meets the steam supply pressure requirement when the unit load is reduced.

[0005] Chinese patent number CN110925037A discloses a method for evaluating the actual peak-shaving capacity of a heating unit taking into account the safety operating margin. This invention is used to evaluate the peak-shaving output range of a heating unit under a specific heating load. However, the extraction steam pressure required by the heating unit is relatively low, and the extraction steam pressure limit can be met under low load conditions, so this invention does not consider the problem of the lower limit of pressure.

[0006] Chinese patent number CN111047168A discloses a method for evaluating the peak-shaving capacity of a heating unit after a high back-pressure heating transformation. The invention is used to evaluate the peak-shaving output of a high back-pressure unit under heating conditions. The invention also does not consider the problem of pressure limitation.

[0007] Therefore, a simple calculation method for the operating domain of the extraction unit considering the extraction pressure limitation is needed to better determine the operating domain of the condensing unit after extraction transformation. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a calculation method and terminal for the operating domain of a condensing unit after extraction modification, which takes into account the limitations caused by the unit in meeting the extraction pressure requirements under low load conditions and can better determine the operating domain of the condensing unit after extraction modification.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0010] A method for calculating the operating domain of a condensing unit after steam extraction transformation comprises the following steps:

[0011] S1. Obtaining the operating data of the condensing unit under the rated state, and calculating the unit operating limit line based on the operating data, wherein the unit operating limit line includes the minimum extraction pressure limit line of the modified unit;

[0012] S2. Determine the operating domain of the condensing unit after the heating transformation based on the determined unit operating limit line.

[0013] In order to solve the above technical problems, another technical solution adopted by the present invention is:

[0014] A computing terminal for the operating domain of a condensing unit after steam extraction modification, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned method for calculating the operating domain of a condensing unit after steam extraction modification are implemented.

[0015] The beneficial effects of the present invention are as follows: a calculation method and terminal for the operating domain of a condensing unit after extraction transformation of the present invention take into account the limitations caused by the unit in meeting the extraction pressure requirements under low load conditions, propose the calculation of the extraction pressure limit line, and further determine the operating domain after the heating transformation of the condensing unit, which solves the problem of imperfect calculation of the current operating domain of the extraction unit and provides a reference basis for the operation of the condensing unit after it is transformed into an extraction unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a method for calculating the operating domain of a condensing unit after steam extraction transformation according to an embodiment of the present invention;

[0017] Figure 2 A structural diagram of a computing terminal in an operation domain of a condensing unit after steam extraction transformation according to an embodiment of the present invention;

[0018] Figure 3 This is an example diagram of the operating domain of a 300MW-class unit calculated by a method for calculating the operating domain of a condensing unit after steam extraction transformation according to an embodiment of the present invention;

[0019] Figure 4This is an example diagram of the operating domain of a 600MW-class unit calculated by a method for calculating the operating domain of a condensing unit after steam extraction transformation according to an embodiment of the present invention;

[0020] Figure 5 This is an example diagram of the operating domain of a 1000MW-class unit calculated by a method for calculating the operating domain of a condensing unit after steam extraction transformation according to an embodiment of the present invention;

[0021] Figure 6 This is a schematic operating domain example diagram for a 300MW unit with low extraction steam pressure and without considering the pressure limit line;

[0022] Description of labels:

[0023] 1. A computing terminal for the operation domain of a condensing unit after steam extraction transformation; 2. A processor; 3. A memory. DETAILED DESCRIPTION

[0024] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0025] Please refer to Figure 1 A method for calculating the operating domain of a condensing unit after steam extraction transformation comprises the following steps:

[0026] S1. Obtaining the operating data of the condensing unit under the rated state, and calculating the unit operating limit line based on the operating data, wherein the unit operating limit line includes the minimum extraction pressure limit line of the modified unit;

[0027] S2. Determine the operating domain of the condensing unit after the heating transformation based on the determined unit operating limit line.

[0028] From the above description, it can be seen that the beneficial effects of the present invention are: a calculation method and terminal for the operating domain of a condensing unit after extraction modification of the present invention take into account the limitations caused by the unit to meet the extraction pressure requirements under low load conditions, proposes the calculation of the extraction pressure limit line, and further determines the operating domain after the heating modification of the condensing unit, which solves the problem of imperfect calculation of the current extraction unit operating domain, and provides a reference basis for the operation of the condensing unit after the modification to the extraction unit.

[0029] Further, the obtaining of the operating data of the condensing unit under the rated state includes:

[0030] Get the main steam flow D under the rated state of the unit 0 , power at rated state N 0 And the high pressure cylinder exhaust pressure P under rated conditions 0 , obtain and calculate the adiabatic specific enthalpy drop ΔH of each stage according to the heat balance diagram under rated conditions x and relative internal efficiency ηx .

[0031] It can be seen from the above description that the operating data of the above-mentioned condensing unit under the rated state is obtained as the basis for subsequent calculations.

[0032] Furthermore, the unit operation limit line includes a minimum condensing condition limit line, and the calculation of the minimum condensing condition limit line is specifically as follows:

[0033] During the operation of the unit, steam must flow through the low-pressure cylinder to remove the heat generated by friction blasting for cooling, so a minimum flow rate is required to pass through the low-pressure cylinder. At this time, the power expression of the steam turbine is:

[0034]

[0035] Where N is power, D is main steam flow, ΔH gz is the adiabatic specific enthalpy drop of the high and medium pressure cylinders, η gz is the relative internal efficiency of the high and medium pressure cylinder, N d It is the power generated when the minimum flow rate flows through the low-pressure cylinder;

[0036] Among them, N and D are in a linear relationship, so the minimum condensing condition limit line of the heating unit can be expressed by the following formula:

[0037] D=α 1 N+α 2 ; (2)

[0038] Among them, α 1 is the slope, α 2 is the intercept,

[0039] It can be seen from the above description that the unit operation limit line includes a minimum condensing condition limit line, and the calculation of the minimum condensing condition limit line is achieved through the above steps.

[0040] Furthermore, the unit operation limit line includes a condensing condition limit line, and the calculation of the condensing condition limit line is specifically as follows:

[0041] When the unit extraction steam volume D cq =0, the relationship curve between unit power and flow is called condensing steam operating line. At this time, there is a linear relationship between actual power and main steam flow, which can be expressed as:

[0042]

[0043] Among them, ΔH is the ideal specific enthalpy drop of the whole machine, η is the relative internal efficiency of the whole machine, D nl is the no-load steam consumption of the steam turbine, α 3 is the slope, α 4 is the intercept, α 4 =D nl .

[0044] It can be seen from the above description that the unit operation limit line includes a condensing condition limit line, and the calculation of the condensing condition limit line is achieved through the above steps.

[0045] Furthermore, the calculation of the minimum extraction steam pressure limit line includes the following steps:

[0046] According to the relationship between steam flow rate D and exhaust pressure P:

[0047]

[0048] Among them, P 0 is the extraction steam pressure under rated load, D 0 is the main steam flow rate under rated load;

[0049] The minimum extraction steam pressure P can be obtained MIN Main steam flow D MIN :

[0050]

[0051] According to the main steam flow D MIN and the suction flow rate D cq , calculate the steam flow rate D flowing through the medium and low pressure cylinders zd :

[0052] D zd =D MIN -D cq ; (6)

[0053] During the load change process of the steam turbine unit, the flow rate through the unit and the power generated by the unit are expressed as:

[0054]

[0055] Among them, N x0 is the power of the unit under rated load, N x1 is the power of the unit under variable operating conditions, D x0 is the flow rate through the unit under rated load, D x1 is the flow rate through the unit under variable operating conditions;

[0056] According to formulas (5), (6) and (7), the relationship between the power generated by the unit and the flow rate can be obtained:

[0057]

[0058] According to formula (3), the following relationship exists between the main steam flow rate and power of the unit:

[0059]

[0060] Combining equations (8) and (9), we can obtain the unit's operating point (N x ,D MIN ), take different extraction steam flow rates for calculation, obtain different operating conditions, and make linear connections to obtain the minimum extraction steam pressure limit line.

[0061] From the above description, it can be seen that the calculation of the minimum extraction steam pressure limit line is realized through the above steps, and the calculation process is relatively simple. The calculation is performed in a simultaneous equation manner, and the iterative calculation without variable operating conditions can significantly shorten the calculation time.

[0062] Furthermore, the unit operation limit line includes a maximum main steam flow limit line, and the maximum main steam flow limit line is determined specifically as follows:

[0063] Main steam flow rate D at rated state 0 As the maximum main steam flow rate, a maximum steam flow rate limit line is obtained.

[0064] From the above description, it can be seen that the main steam flow rate D under the rated state of the unit can be 0 As the maximum main steam flow.

[0065] Furthermore, the unit operation limit line includes a minimum main steam flow limit line, and the minimum main steam flow limit line is determined specifically as follows:

[0066] The preset percentage value of the maximum main steam flow rate is used as the minimum main steam flow rate to obtain the minimum main steam flow rate limit line.

[0067] From the above description, it can be seen that the minimum main steam flow rate is generally about 30% of the BMCR operating condition.

[0068] Please refer to Figure 2 A computing terminal for the operating domain of a condensing unit after steam extraction modification, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned method for calculating the operating domain of a condensing unit after steam extraction modification are implemented.

[0069] The present invention provides a method and a terminal for calculating the operating domain of a condensing unit after steam extraction transformation, which are suitable for calculating the operating domain of a condensing unit after steam extraction transformation.

[0070] Please refer to Figure 1 as well as Figures 3 to 6 , Embodiment 1 of the present invention is:

[0071] A method for calculating the operating domain of a condensing unit after steam extraction transformation comprises the following steps:

[0072] S1. Obtaining the operating data of the condensing unit under the rated state, and calculating the unit operating limit line based on the operating data, wherein the unit operating limit line includes the minimum steam extraction pressure limit line of the modified unit.

[0073] In this embodiment, the unit after modification is a single-stage extraction unit, and the extraction port is set at the high-pressure cylinder exhaust. The minimum condensing condition limit line, condensing condition limit line, maximum main steam flow limit line, minimum main steam flow limit line, and minimum extraction pressure limit line of the unit are determined by calculation, and finally the operating domain of the condensing unit after heating modification is determined.

[0074] First, it is necessary to obtain the operating data of the condensing unit under rated conditions. Refer to the unit design parameters to obtain the main steam flow rate D under rated conditions of the unit. 0 (This flow rate can be used as the maximum main steam flow rate), power N under rated conditions 0 , High pressure cylinder exhaust pressure P under rated conditions 0 ; Obtain and calculate the adiabatic specific enthalpy drop ΔH of each stage based on the heat balance diagram under rated conditions x and relative internal efficiency η x Among them, the minimum main steam flow is generally about 30% of the BMCR working condition. BMCR is the maximum continuous evaporation capacity of the boiler, which is mainly the maximum output under the condition of meeting steam parameters and furnace safety, that is, the maximum main steam flow. In this embodiment, 30% of the maximum main steam flow is the minimum main steam flow.

[0075] The calculation of the minimum condensing condition limit line is as follows:

[0076] During the operation of the unit, steam must flow through the low-pressure cylinder to remove the heat generated by friction blasting for cooling, so a minimum flow rate is required to pass through the low-pressure cylinder. At this time, the power expression of the steam turbine is:

[0077]

[0078] Where N is power, MW; D is main steam flow, t / h; ΔH gz is the adiabatic specific enthalpy drop of the high and medium pressure cylinders, kJ / kg; η gz is the relative internal efficiency of high and medium pressure cylinders; N d The power generated when the low-pressure cylinder flows through the minimum flow, MW, N d It can be regarded as a constant, and the values ​​calculated by different units are different;

[0079] Among them, N and D are in a linear relationship, so the minimum condensing condition limit line of the heating unit can be expressed by the following formula:

[0080] D=α 1 N+α 2 ; (2)

[0081] Among them, α 1 is the slope, α 1 Can be approximated as a constant, and the values ​​calculated for different units are different; α 2 is the intercept, is a constant.

[0082] Calculation of condensing condition limit line of the modified unit:

[0083] When the unit extraction steam volume D cq = 0, the relationship curve between unit power and flow is called the condensing condition line. At this time, according to the literature [3], there is a linear relationship between the actual power of the steam turbine and the main steam flow, expressed as:

[0084]

[0085] Where, ΔH is the ideal specific enthalpy drop of the whole machine, kJ / kg; η is the relative internal efficiency of the whole machine; D nl is the no-load steam consumption of the steam turbine, t / h, which is a constant; α 3 is the slope, α 3 Can be approximated as a constant, and the values ​​calculated for different units are different; α 4 is the intercept, α 4 =D nl .

[0086] The calculation of the minimum extraction steam pressure limit line includes the following steps:

[0087] After the condensing unit is converted into a steam supply unit, the extraction steam is limited by the minimum extraction steam pressure in order to meet the steam supply pressure requirements. Under low load conditions, the high-pressure cylinder exhaust parameters may not meet the required extraction steam pressure requirements, so it is necessary to add a minimum extraction steam pressure limit line.

[0088] According to the Flugel formula, the relationship between the steam flow rate D and the extraction pressure P under variable operating conditions of the unit is:

[0089]

[0090] Among them, P 0 D is the extraction steam pressure under rated load, MPa; 0 is the main steam flow rate under rated load, t / h;

[0091] The minimum extraction steam pressure P can be obtained MIN Main steam flow D MIN :

[0092]

[0093] P MIN is the minimum extraction steam pressure, MPa; D MIN is the main steam flow rate corresponding to the minimum extraction pressure, t / h;

[0094] The main steam flow D calculated according to formula (5) MIN And the extraction steam flow D at this time cq , the steam flow rate D flowing through the medium and low pressure cylinders can be obtained zd :

[0095] D zd =D MIN -D cq ; (6)

[0096] Among them, D zd is the steam flow rate flowing through the medium and low pressure cylinders, t / h;

[0097] During the load change process of the steam turbine unit, the flow rate flowing through the unit and the power generated by the unit are approximately proportional, which can be expressed as:

[0098]

[0099] Among them, N x0 is the power of the unit under rated load, MW; N x1 is the power of the unit under variable operating conditions, MW; D x0 is the flow rate flowing through the stage group under rated load, t / h; D x1 is the flow rate flowing through the stage group under variable working conditions, t / h;

[0100] According to formulas (5), (6) and (7), the relationship between the power generated by the unit and the flow rate can be obtained:

[0101]

[0102] Among them, N x Indicates the power of the unit under non-rated conditions, N 0 Indicates the power of the unit under rated operating conditions;

[0103] When the steam extraction volume D cq When is a certain value, according to formula (3), it can be known that there is the following relationship between the main steam flow rate and power of the unit:

[0104]

[0105] Where ΔH zd is the adiabatic specific enthalpy drop of the medium and low pressure cylinders, kJ / kg; η zd is the relative internal efficiency of the medium and low pressure cylinders; It can be regarded as a constant, and the values ​​calculated by different units are different.

[0106] Combining equations (8) and (9), we can obtain the unit's operating point (N x ,D MIN ), take different extraction steam flow rates for calculation, obtain different operating conditions, and make linear connections to obtain the minimum extraction steam pressure limit line.

[0107] S2. Determine the operating domain of the condensing unit after the heating transformation based on the determined unit operating limit line.

[0108] In this embodiment, the following examples are provided:

[0109] (1) Take a 300MW unit as an example. The turbine model is N350-16.7 / 538 / 538. The unit parameters are shown in Table 1. The steam supply parameters are 2.79MPa and 290℃. Under the condition of meeting this steam supply demand, the operating domain of this 300MW unit is calculated as follows: Figure 3 shown.

[0110] Table 1

[0111] parameter Numeric unit Rated Power 350 MW Main steam pressure 16.7 MPa Main steam temperature 538 ℃ Reheat temperature 538 ℃ Main steam flow 1040.76 t / h Exhaust pressure 5.2 KPa Heat rate 7830.2 kJ / kWh

[0112] (2) Taking a 600MW supercritical unit as an example, the turbine model is N600-24.2 / 566 / 566, and the unit parameters are shown in Table 2. The steam supply parameters are 2.79MPa and 290℃. Under the condition of meeting this steam supply demand, through calculation, the operating domain of this 600MW unit is as follows: Figure 4 shown.

[0113] Table 2

[0114]

[0115]

[0116] (3) Take a 1000MW unit as an example. The turbine model is N1000-27 / 600 / 600. The unit parameters are shown in Table 3. The steam supply parameters are 2.79MPa and 290℃. Under the condition of meeting this steam supply demand, the operating domain of this 1000MW unit is calculated as follows: Figure 5 shown.

[0117] Table 3

[0118] parameter Numeric unit Rated Power 1000 MW Main steam pressure 25 MPa Main steam temperature 600 ℃ Reheat temperature 600 ℃ Main steam flow 2729.51 t / h Exhaust pressure 4.9 KPa Heat rate 7309.8 kJ / kWh

[0119] (4) Figure 6 This is a schematic operating domain when the extraction pressure of a 300MW unit is low and the pressure limit line is not considered. By comparing it with the operating domain calculated by the present invention, it can be found that if there is no extraction pressure limit line, the unit can reduce the load to the load corresponding to the minimum main steam flow rate. If the extraction pressure is limited, in order to meet the extraction pressure requirement, the unit load cannot be reduced to too low.

[0120] Please refer to Figure 2 , Embodiment 2 of the present invention is:

[0121] A computing terminal 1 for an operating domain of a condensing unit after steam extraction modification, comprising a processor 2, a memory 3, and a computer program stored in the memory 3 and executable on the processor 2. When the processor 2 executes the computer program, the steps in a method for calculating an operating domain of a condensing unit after steam extraction modification in the above embodiment 1 are implemented.

[0122] In summary, the present invention provides a method and terminal for calculating the operating domain of a condensing unit after extraction modification, which takes into account the limitations of the unit under low load conditions to meet the extraction pressure requirements, proposes the calculation of the extraction pressure limit line, and further determines the operating domain of the condensing unit after the heating modification, thereby solving the problem of imperfect calculation of the current operating domain of the extraction unit and providing a reference for the operation of the condensing unit after it is modified into an extraction unit.

[0123] The calculation process of the present invention is relatively simple, and the calculation is performed by means of simultaneous equations, and the iterative calculation without variable working conditions can significantly shorten the calculation time. The unit operation domain calculated by the present invention can also provide a reference basis for the power grid dispatching department to determine the unit operation mode.

[0124] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for calculating the operating domain of a condensing unit after steam extraction transformation, characterized in that: Includes steps: S1. Obtaining the operating data of the condensing unit under the rated state, and calculating the unit operating limit line based on the operating data, wherein the unit operating limit line includes the minimum extraction pressure limit line of the modified unit; The obtaining of the operating data of the condensing unit under the rated state comprises: Get the main steam flow rate at rated state of the unit , power at rated state And the high pressure cylinder exhaust pressure under rated conditions , obtain and calculate the adiabatic specific enthalpy drop of each stage according to the heat balance diagram under rated conditions Relative internal efficiency ; The unit operation limit line includes a condensing condition limit line, and the calculation of the condensing condition limit line is specifically as follows: When the unit extraction steam When the power of the unit is 0.04W, the relationship curve between the power and the flow is called the condensing condition line. At this time, the actual power and the main steam flow are in a linear relationship, which can be expressed as: ；（3） in, is the ideal specific enthalpy drop of the whole machine, is the relative internal efficiency of the whole machine, is the no-load steam consumption of the steam turbine, is the slope, , is the intercept, ; The calculation of the minimum extraction steam pressure limit line includes the following steps: According to the relationship between steam flow rate D and exhaust pressure P: ；（4） in, is the extraction steam pressure under rated load, is the main steam flow rate under rated load; The minimum extraction steam pressure can be met Main steam flow rate : ； （5） According to the main steam flow at this time and suction flow , calculate the steam flow through the medium and low pressure cylinders : ； （6） During the load change process of the steam turbine unit, the flow rate through the unit and the power generated by the unit are expressed as: ；（7） in, is the power of the unit under rated load, is the power of the unit under variable operating conditions, is the flow rate through the unit under rated load, is the flow rate through the unit under variable operating conditions; According to formulas (5), (6) and (7), the relationship between the power generated by the unit and the flow rate can be obtained: ；（8） in, Indicates the power of the unit under non-rated conditions. Indicates the power of the unit under rated operating conditions; According to formula (3), there is the following relationship between the main steam flow rate and power of the unit: ;（9） Combining formulas (8) and (9), the operating point of the unit can be obtained ( ), take different extraction steam flow rates for calculation, obtain different operating conditions, and make linear connections to obtain the minimum extraction steam pressure limit line; S2. Determine the operating domain of the condensing unit after the heating transformation based on the determined unit operating limit line.

2. The method for calculating the operating domain of a condensing unit after steam extraction transformation according to claim 1 is characterized in that: The unit operation limit line includes a minimum condensing condition limit line, and the calculation of the minimum condensing condition limit line is specifically as follows: During the operation of the unit, steam must flow through the low-pressure cylinder to remove the heat generated by friction blasting for cooling, so a minimum flow rate is required to pass through the low-pressure cylinder. At this time, the power expression of the steam turbine is: ；（1） Among them, N is power, D is main steam flow, is the adiabatic specific enthalpy drop of the high and medium pressure cylinders, is the relative internal efficiency of the high and medium pressure cylinders, It is the power generated when the minimum flow rate flows through the low-pressure cylinder; Among them, N and D are in a linear relationship, so the minimum condensing condition limit line of the heating unit can be expressed by the following formula: ；（2） in, is the slope, , is the intercept, .

3. The method for calculating the operating domain of a condensing unit after steam extraction transformation according to claim 1 is characterized in that: The unit operation limit line includes a maximum main steam flow limit line, and the maximum main steam flow limit line is determined as follows: Main steam flow at rated state As the maximum main steam flow rate, a maximum steam flow rate limit line is obtained.

4. The method for calculating the operating domain of a condensing unit after steam extraction transformation according to claim 3 is characterized in that: The unit operation limit line includes a minimum main steam flow limit line, and the determination of the minimum main steam flow limit line is specifically as follows: The preset percentage value of the maximum main steam flow rate is used as the minimum main steam flow rate to obtain the minimum main steam flow rate limit line.

5. A computing terminal for the operation domain of a condensing unit after steam extraction transformation, comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps in the method for calculating the operating domain of a condensing unit after steam extraction transformation according to any one of claims 1 to 4 are implemented.

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