Method for evaluating pressure of through-flow part of high-pressure cylinder of steam turbine

Abstract

The invention discloses a steam turbine high-pressure cylinder through-flow part pressure evaluation method, which comprises the following steps: adjusting the actual high-pressure cylinder through-flow part pressure to the same control valve opening degree, rated main steam pressure and rated main steam temperature through primary correction and secondary correction to obtain the corrected high-pressure cylinder through-flow part pressure PtII; and comparing the corrected pressure PtII of the through-flow part of the high-pressure cylinder with a rated pressure value # imgabs0 # of the through-flow part of the high-pressure cylinder. During operation, when # imgabs 1 #, the pressure of the through-flow part of the high-pressure cylinder is evaluated to be abnormal.

Description

Technical Field

[0001] The invention relates to a method for evaluating the pressure of a flow-through part of a high-pressure cylinder of a steam turbine, belonging to the technical field of thermal power generation. Background Art

[0002] The pressure of the high-pressure cylinder flow passage is an important basis for monitoring whether the turbine is intact during operation. Field tests are currently the main channel for obtaining turbine operating parameters and characteristic information, but the health status of the equipment changes all the time, and performance aging is an objective law. Conventional test results can only represent the equipment and operating status at the time, with short timeliness and poor sustainability.

[0003] In order to facilitate operating personnel to timely understand the status of the steam turbine and scientifically evaluate whether the pressure of the high-pressure cylinder flow section is abnormal, the present invention proposes a method for evaluating the pressure of the high-pressure cylinder flow section of a steam turbine. Summary of the invention

[0004] The purpose of the present invention is to facilitate operating personnel to timely understand the status of the steam turbine and scientifically evaluate whether the pressure of the high-pressure cylinder flow part is abnormal. The present invention proposes a method for evaluating the pressure of the high-pressure cylinder flow part of the steam turbine.

[0005] The technical solution implemented by the present invention is as follows: A method for evaluating the pressure of the flow section of the high-pressure cylinder of a steam turbine, wherein the method adjusts the actual flow section pressure of the high-pressure cylinder to the same throttle opening and rated main steam pressure and rated main steam temperature through primary and secondary corrections, and obtains the corrected pressure P of the flow section of the high-pressure cylinder tII ; The corrected high pressure cylinder flow pressure P tII Pressure rating of the part flowing through the high-pressure cylinder During operation, when When the pressure in the flow section is abnormal, the abnormal pressure is evaluated.

[0006] The method is to adjust the valve opening, the main steam pressure P0, the main steam temperature T0, the pressure of the high-pressure cylinder flow part P t and temperature T t The dead zone of other parameters is less than 0.1%, retaining three decimal places, and added to the DCS historical database. t and temperature T t It includes the pressure and temperature of the regulating stage, the pressure and temperature after the first stage of the high-pressure cylinder, and the pressure and temperature after the second stage of the high-pressure cylinder.

[0007] The method continuously and synchronously collects the valve opening, main steam pressure P0, main steam temperature T0, high pressure cylinder flow pressure P t and temperature T t , the sampling frequency of the test point is set to 1 time / second.

[0008] The pressure ratio of each stage in the method includes the pressure ratio of the regulating stage, the pressure ratio of the first stage of the high-pressure cylinder and the pressure ratio of the second stage of the high-pressure cylinder. The pressure ratio of each stage under different regulating valve openings is equal to the corresponding high-pressure cylinder flow part pressure divided by the main steam pressure.

[0009]

[0010] Where: ε t is the stage pressure ratio; P t It is the flow pressure of the high-pressure cylinder; P0 is the main steam pressure.

[0011] The method is calculated according to formula (2) to obtain the pressure P of the high-pressure cylinder flow part after the first correction under different valve openings: tI :

[0012]

[0013] Where: P tI P′ is the flow pressure of the high-pressure cylinder after the first calibration; t is the actual flow pressure; is the rated main steam pressure; P′0 is the actual main steam pressure; is the rated main steam temperature; T′0 is the actual main steam temperature; At rated main steam pressure and rated main steam temperature The rated high-pressure cylinder flow temperature corresponding to the valve opening; T' t It is the actual temperature of the flow passage of the high pressure cylinder.

[0014] The method uses the pressure ratio of each stage at different throttle openings, rated main steam pressure, and rated main steam temperature as the reference value; the reference value of the pressure ratio of each stage The actual measurement can be carried out by gradually closing the regulating valve at the rated main steam pressure and rated main steam temperature. Under the same regulating valve opening, the deviation percentage of the pressure ratio of each stage is calculated according to formula (3):

[0015]

[0016] Where: is the deviation percentage of the pressure ratio of each stage; is the reference value of the pressure ratio of each stage; ε t is the pressure ratio of each stage.

[0017] The method uses the pressure of the high-pressure cylinder flow part after the first calibration at different throttle openings, rated main steam pressure, and rated main steam temperature as a reference value; the reference value of the pressure of the high-pressure cylinder flow part after the first calibration The actual measurement can be carried out by gradually closing the regulating valve at the rated main steam pressure and rated main steam temperature. Under the same regulating valve opening, the deviation percentage θ of the pressure of the high-pressure cylinder flow part after the first correction is calculated according to formula (4): t .

[0018]

[0019] Where: θ t It is the deviation percentage of the pressure of the flow part of the high-pressure cylinder after the first calibration; P is the reference value of the pressure of the high-pressure cylinder flow section after the first calibration; tI It is the flow pressure of the high-pressure cylinder after the first calibration.

[0020] The method uses the spreadsheet software to calculate the deviation percentage of each stage pressure ratio under different throttle openings. As the horizontal axis parameter, the deviation percentage of the pressure after the first calibration is θ t As the ordinate parameter, a two-dimensional scatter plot is generated and a linear fit is performed to obtain the relationship between the two

[0021] The method is calculated according to formula (5) to obtain the pressure P of the high-pressure cylinder flow part after the second correction under different valve openings: tII :

[0022]

[0023] Where: P tII It is the flow pressure of the high-pressure cylinder after the second calibration.

[0024] The method is to calculate the pressure of the high-pressure cylinder flow part at different throttle valve openings, rated main steam pressure and rated main steam temperature. As the rated value; the actual high-pressure cylinder flow pressure must be adjusted to the same valve opening and rated parameters before comparison. When the pressure in the flow section is abnormal, the abnormal pressure is evaluated.

[0025] The beneficial effect of the present invention is that the operating personnel can timely understand the status of the steam turbine without relying on third-party tests, and scientifically evaluate whether the pressure of the flow part of the high-pressure cylinder is abnormal, thereby providing a basis for the operation and maintenance of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a schematic diagram of the flow passage of the high-pressure cylinder according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is shown in the figure. Figure 1 , clearly and completely describe the technical solutions in the embodiments of the present invention.

[0029] The embodiment of the present invention provides a method for evaluating the pressure of a flow passage portion of a high-pressure cylinder of a steam turbine, comprising the following steps:

[0030] The method adjusts the actual high-pressure cylinder flow pressure to the same throttle opening, rated main steam pressure and rated main steam temperature through primary and secondary corrections to obtain the corrected high-pressure cylinder flow pressure P tII ; The corrected high pressure cylinder flow pressure P tII Pressure rating of the part flowing through the high-pressure cylinder During operation, when When the pressure in the flow section is abnormal, the abnormal pressure is evaluated.

[0032] The method is to adjust the valve opening, the main steam pressure P0, the main steam temperature T0, the pressure of the high-pressure cylinder flow part P t and temperature T t The dead zone of other parameters is less than 0.1%, retaining three decimal places, and added to the DCS historical database. t and temperature T t It includes the pressure and temperature of the regulating stage, the pressure and temperature after the first stage of the high-pressure cylinder, and the pressure and temperature after the second stage of the high-pressure cylinder.

[0033] The method continuously and synchronously collects the valve opening, main steam pressure P0, main steam temperature T0, high pressure cylinder flow pressure P t and temperature T t , the sampling frequency of the test point is set to 1 time / second.

[0034] The pressure ratio of each stage in the method includes the pressure ratio of the regulating stage, the pressure ratio of the first stage of the high-pressure cylinder and the pressure ratio of the second stage of the high-pressure cylinder. The pressure ratio of each stage under different regulating valve openings is equal to the corresponding high-pressure cylinder flow part pressure divided by the main steam pressure.

[0035]

[0036] Where: ε t is the stage pressure ratio; P t It is the flow pressure of the high-pressure cylinder; P0 is the main steam pressure.

[0037] The method is calculated according to formula (2) to obtain the pressure P of the high-pressure cylinder flow part after the first correction under different valve openings: tI :

[0038]

[0039] Where: P tI P′ is the flow pressure of the high-pressure cylinder after the first calibration; t is the actual flow pressure; is the rated main steam pressure; P′0 is the actual main steam pressure; is the rated main steam temperature; T′0 is the actual main steam temperature; At rated main steam pressure and rated main steam temperature The rated high-pressure cylinder flow temperature corresponding to the valve opening; T' t It is the actual temperature of the flow passage of the high pressure cylinder.

[0040] The method uses the pressure ratio of each stage at different throttle openings, rated main steam pressure, and rated main steam temperature as the reference value; the reference value of the pressure ratio of each stage The actual measurement can be carried out by gradually closing the regulating valve at the rated main steam pressure and rated main steam temperature. Under the same regulating valve opening, the deviation percentage of the pressure ratio of each stage is calculated according to formula (3):

[0041]

[0042] Where: is the deviation percentage of the pressure ratio of each stage; is the reference value of the pressure ratio of each stage; ε t is the pressure ratio of each stage.

[0043] The method uses the pressure of the high-pressure cylinder flow part after the first calibration at different throttle openings, rated main steam pressure, and rated main steam temperature as a reference value; the reference value of the pressure of the high-pressure cylinder flow part after the first calibration The actual measurement can be carried out by gradually closing the regulating valve at the rated main steam pressure and rated main steam temperature. Under the same regulating valve opening, the deviation percentage θ of the pressure of the high-pressure cylinder flow part after the first correction is calculated according to formula (4): t .

[0044]

[0045] Where: θ t It is the deviation percentage of the pressure of the flow part of the high-pressure cylinder after the first calibration; P is the reference value of the pressure of the high-pressure cylinder flow section after the first calibration; tI It is the flow pressure of the high-pressure cylinder after the first calibration.

[0046] The method uses the spreadsheet software to calculate the deviation percentage of each stage pressure ratio under different throttle openings. As the horizontal axis parameter, the deviation percentage of the pressure after the first calibration is θ t As the ordinate parameter, a two-dimensional scatter plot is generated and a linear fit is performed to obtain the relationship between the two

[0047] The method is calculated according to formula (5) to obtain the pressure P of the high-pressure cylinder flow part after the second correction under different valve openings: tII :

[0048]

[0049] Where: P tII It is the flow pressure of the high-pressure cylinder after the second calibration.

[0050] The method is to calculate the pressure of the high-pressure cylinder flow part at different throttle valve openings, rated main steam pressure and rated main steam temperature. As the rated value; the actual high-pressure cylinder flow pressure must be adjusted to the same valve opening and rated parameters before comparison. When the pressure in the flow section is abnormal, the abnormal pressure is evaluated.

[0051] The above is a detailed introduction to a method for evaluating the pressure of the flow passage of a high-pressure cylinder of a steam turbine provided by the present invention. In this embodiment, a specific example is used to illustrate the principle and implementation method of the present invention. The description of the above embodiment is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine, characterized in that: The method adjusts the actual high-pressure cylinder flow pressure to the same throttle opening, rated main steam pressure and rated main steam temperature through primary and secondary corrections to obtain the corrected high-pressure cylinder flow pressure P tII ; The corrected high pressure cylinder flow pressure P tII Pressure rating of the part flowing through the high-pressure cylinder For comparison, when running When evaluating the abnormal pressure in the flow passage of the high-pressure cylinder.

2. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: The method is to adjust the valve opening, the main steam pressure P0, the main steam temperature T0, the pressure of the high-pressure cylinder flow part P t and temperature T t Record the dead zone less than 0.1%, retain three decimal places, and add it to the DCS historical database, where the pressure of the high-pressure cylinder flow part P t and temperature T t It includes the pressure and temperature of the regulating stage, the pressure and temperature after the first stage of the high-pressure cylinder, and the pressure and temperature after the second stage of the high-pressure cylinder.

3. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: During operation, the valve opening, main steam pressure P0, main steam temperature T0, and high-pressure cylinder flow pressure P are continuously and synchronously collected. t and temperature T t , the sampling frequency of the test point is set to 1 time / second.

4. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: The pressure ratio of each stage of the method includes the pressure ratio of the regulating stage, the pressure ratio of the first stage of the high-pressure cylinder and the pressure ratio of the second stage of the high-pressure cylinder. The pressure ratio of each stage under different regulating valve openings is equal to the corresponding high-pressure cylinder flow pressure divided by the main steam pressure, and the expression is: In the formula, ε t is the stage pressure ratio, P t It is the flow pressure of the high-pressure cylinder, and P0 is the main steam pressure.

5. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: Calculate the pressure P of the high-pressure cylinder flow section after the first correction under different throttle openings tI , the expression is: Where P tI is the flow pressure of the high-pressure cylinder after the first calibration, P′ t is the actual flow pressure, is the rated main steam pressure, P′0 is the actual main steam pressure, is the rated main steam temperature, T′0 is the actual main steam temperature, At rated main steam pressure and rated main steam temperature The rated high-pressure cylinder flow temperature corresponding to the valve opening is T' t It is the actual temperature of the flow passage of the high pressure cylinder.

6. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: The pressure ratio of each stage at different throttle valve openings, rated main steam pressure and rated main steam temperature is taken as the reference value; the reference value of the pressure ratio of each stage The actual measurement can be carried out by gradually closing the regulating valve at the rated main steam pressure and rated main steam temperature. Under the same regulating valve opening, calculate the deviation percentage of the pressure ratio of each stage. The expression is: In the formula, is the deviation percentage of the pressure ratio of each stage, is the reference value of the pressure ratio of each stage, ε t is the pressure ratio of each stage.

7. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: The pressure of the high-pressure cylinder flow section after the first calibration at different throttle openings, rated main steam pressure, and rated main steam temperature is taken as the reference value; the reference value of the pressure of the high-pressure cylinder flow section after the first calibration The deviation percentage θ of the pressure of the high-pressure cylinder flow section after the first correction can be calculated by gradually closing the throttle valve at the rated main steam pressure and rated main steam temperature for actual measurement and at the same throttle valve opening. t , the expression is: In the formula, θ t is the deviation percentage of the pressure of the high-pressure cylinder flow section after the first calibration, P is the reference value of the pressure of the high-pressure cylinder flow section after the first calibration. tI It is the flow pressure of the high-pressure cylinder after the first calibration.

8. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: The deviation percentage of each stage pressure ratio under different throttle openings As the horizontal axis parameter, the deviation percentage of the pressure after the first calibration is θ t As the ordinate parameter, a two-dimensional scatter plot is generated and linear fitting is performed, and the relationship between the two is obtained as follows: a and b are both constants.

9. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: The pressure P of the high-pressure cylinder flow section after the second correction under different throttle openings is calculated. tII , the expression is: Where: P tII P is the flow pressure of the high-pressure cylinder after the second calibration. tI It is the flow pressure of the high-pressure cylinder after the first calibration. is the deviation percentage of the pressure ratio of each stage, and a and b are constants.

10. A method for evaluating the pressure of a flow passage of a high-pressure cylinder of a steam turbine according to claim 1, characterized in that: The pressure of the high-pressure cylinder flow section at different throttle openings, rated main steam pressure and rated main steam temperature As the rated value; the actual high-pressure cylinder flow pressure must be adjusted to the same valve opening and rated parameters before comparison. When evaluating the abnormal pressure in the flow passage of the high-pressure cylinder.

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