CN117288398A

CN117288398A - System for testing steam leakage rate of intermediate shaft seal of high-medium pressure cylinder and calculating method

Info

Publication number: CN117288398A
Application number: CN202311108773.7A
Authority: CN
Inventors: 杨海生; 张伟江; 李铁军; 李泽敏
Original assignee: State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd; State Grid Hebei Energy Technology Service Co Ltd
Current assignee: State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Hebei Electric Power Co Ltd; State Grid Hebei Energy Technology Service Co Ltd
Priority date: 2023-08-30
Filing date: 2023-08-30
Publication date: 2023-12-26

Abstract

The invention provides a system and a method for testing and calculating the steam leakage rate of an intermediate shaft seal of a high-medium pressure cylinder. The method comprises the following steps: acquiring a first operation parameter in the intermediate shaft seal steam leakage rate test system of the high and medium pressure cylinders when the leakage test valve is in a fully opened state under a rated working condition; calculating the steam through-flow rate passing through the leakage test valve according to the first operation parameter; when the steam through-flow meets a first preset condition, acquiring second operation parameters corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system when the leakage test valve is in a full-open or full-closed state under different preset working conditions, and calculating the high and medium pressure cylinder intermediate shaft seal steam leakage rate according to the second operation parameters. The method can solve the problem that the steam leakage state of the intermediate shaft seal of the high-medium pressure cylinder of the steam turbine cannot be accurately monitored efficiently in the prior art, and provides accurate reference data for overhauling the steam turbine body.

Description

System for testing steam leakage rate of intermediate shaft seal of high-medium pressure cylinder and calculating method

Technical Field

The invention relates to the technical field of thermal performance test of steam turbines, in particular to a system and a method for testing the steam leakage rate of an intermediate shaft seal of a high-medium pressure cylinder.

Background

The size of the steam leakage of the steam seal of the steam turbine directly influences the working capacity and performance of the normal operation of the steam turbine. In the running parameters of the inter-cylinder shaft seal of the steam turbine of the power plant, the leakage flow of the inter-cylinder shaft seal most intuitively reflects the working state of the shaft seal, and under the same running boundary condition, the lower the leakage flow of the shaft seal of the middle shaft seal leakage channel of the high-middle pressure cylinder of the steam turbine is, the better the running state of the inter-cylinder shaft seal is.

The shaft seal leakage amount of the middle shaft seal leakage channel of the high-pressure cylinder in the existing power plant cannot be directly measured, and when the shaft seal leakage rate of the middle shaft seal leakage channel of the high-pressure cylinder is determined by adopting test modes such as steam temperature change and the like, the field test adjustment workload is too large, so that the state of shaft seal leakage of the middle shaft seal leakage channel of the high-pressure cylinder of the steam turbine cannot be accurately monitored.

Disclosure of Invention

The embodiment of the invention provides a high and medium pressure cylinder intermediate shaft seal leakage rate test system and a calculation method, which are used for solving the problem that the state of shaft seal leakage of a high and medium pressure cylinder intermediate shaft seal leakage channel of a steam turbine cannot be accurately monitored in the prior art.

In a first aspect, an embodiment of the present invention provides a system for testing a leakage rate of an intermediate shaft seal of a high-medium pressure cylinder, including: a leakage branch pipeline, a leakage test valve and a condenser;

The steam inlet end of the leakage branch pipeline is connected to a leakage channel of the intermediate shaft seal of the high-medium pressure cylinder, and the steam outlet end of the leakage branch pipeline is connected to the condenser; an n-level shaft seal is arranged on the middle shaft seal leakage channel of the high-medium pressure cylinder, and the leakage branch pipeline to the condenser is connected to the back of an m-level shaft seal along the flowing direction of leakage steam, wherein n and m are positive integers, and m is smaller than n;

the leak test valve is disposed on the leak branch line.

In a second aspect, an embodiment of the present invention provides a method for calculating a steam leakage rate of an intermediate shaft seal of a high and medium pressure cylinder, where the method for calculating the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinder includes:

acquiring a first operation parameter in the intermediate shaft seal steam leakage rate test system of the high and medium pressure cylinders when the leakage test valve is in a fully opened state under a rated working condition;

calculating the steam through-flow rate passing through the leakage test valve according to the first operation parameter;

when the steam through-flow meets a first preset condition, acquiring second operation parameters corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system when the leakage test valve is in a full-open or full-closed state under different preset working conditions, and calculating the high and medium pressure cylinder intermediate shaft seal steam leakage rate according to the second operation parameters.

In one possible implementation of the present invention,

the first operating parameter includes: critical pressure drop ratio x of the leak test valve _T Valve flow coefficient K _v And the steam pressure P after the high-pressure cylinder adjusts the stage when the leakage test valve is in the full-open state under the rated working condition _csd And steam temperature t _csd Steam pressure P before steam inlet valve of medium pressure cylinder _IPin1d The pressure loss PS is designed for a steam inlet valve of the medium pressure cylinder;

the calculating the steam through-flow through the leak test valve according to the first operating parameter includes:

according toCalculating the steam inlet pressure of the medium pressure cylinder when the leakage test valve is in a full-open state under the rated working condition;

according toCalculating the steam pressure at the inlet position of the leakage branch pipeline when the leakage test valve is in the full-open state under the rated working condition;

according to t _vind ＝tph[P _vind ,hpt(P _csd ,t _csd )]Calculating the steam temperature of the inlet position of the leakage branch pipeline when the leakage test valve is in the full-open state under the rated working condition;

according toCalculating the steam through-flow rate passing through the leakage test valve;

wherein W is _d Represents the flow rate of the steam through the leak test valve, P _IPin3d Represents the steam inlet pressure, P, of the medium pressure cylinder when the leakage test valve is in the full-open state under the rated working condition _vind The steam pressure and the steam temperature of the inlet position of the leakage branch pipeline when the leakage test valve is in the full open state under the rated working condition are represented, n represents the total number of shaft seal stages arranged on a shaft seal leakage steam channel in the middle of the high and medium pressure cylinder, m represents the number of shaft seal stages (counted along the flow direction of shaft seal leakage steam) of the leakage branch pipeline connected to the position upstream of the shaft seal leakage steam channel in the middle of the high and medium pressure cylinder, and t _vind The steam temperature of the inlet position of the leakage branch pipeline when the leakage test valve is in a full-open state under the rated working condition is represented, hpt (P, t) is a steam-water characteristic function for solving the enthalpy value of the medium according to the pressure and the temperature of the medium, tph (P, h) is a steam-water characteristic function for solving the enthalpy value of the medium according to the pressure and the enthalpy value of the medium, cppt (P, t) is a steam-water characteristic function for solving the constant pressure specific heat of the medium according to the pressure and the temperature of the medium, cvpt (P, t) is a steam-water characteristic function for solving the constant specific heat of the medium according to the pressure and the temperature of the medium, and vpt (P, t) is a steam-water characteristic function for solving the specific heat of the medium according to the pressure and the temperature of the medium.

In one possible implementation manner, determining that the steam through-flow rate meets a first preset condition includes:

when the steam through-flow is larger than the preset multiple of the leakage flow designed by the intermediate shaft seal of the high-medium pressure cylinder, determining that the steam through-flow meets a first preset condition;

further comprises: when the steam through-flow rate does not meet the first preset condition, replacing the leakage test valve, and jumping to the step of acquiring the first operation parameter in the intermediate shaft seal leakage rate test system of the high and medium pressure cylinders when the leakage test valve is in the full-open state under the rated working condition, and executing the subsequent steps until the steam through-flow rate meets the first preset condition.

In one possible implementation, the second operating parameter includes a third operating parameter, a fourth operating parameter, and a fifth operating parameter;

and under different preset working conditions, acquiring a second operation parameter corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system when the leakage test valve is in a fully opened or fully closed state, and calculating the high and medium pressure cylinder intermediate shaft seal steam leakage rate according to the second operation parameter, wherein the method comprises the following steps:

when the leakage test valve is in a fully-opened state, acquiring a third operation parameter corresponding to the high and medium pressure cylinder intermediate shaft seal leakage rate test system under a current first preset working condition and a fourth operation parameter corresponding to the high and medium pressure cylinder intermediate shaft seal leakage rate test system under a current second preset working condition, wherein the rated load of a unit of the first preset working condition and the rated load of the unit of the second preset working condition differ by more than 15 percent;

calculating the medium pressure cylinder through-flow efficiency when the leakage test valve is in a full-open state under the current first preset working condition according to the third operation parameter;

calculating the medium pressure cylinder through-flow efficiency when the leakage test valve is in a full-open state under the current second preset working condition according to the fourth operation parameter;

When the current medium pressure cylinder through-flow efficiency when the leakage test valve is in a full-open state under the first preset working condition and the current medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the second preset working condition meet the second preset condition, obtaining a fifth operation parameter corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system when the leakage test valve is in a full-closed state under the second preset working condition;

and calculating the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to the fifth operation parameter.

In one possible implementation, the method further includes:

when the current medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the first preset working condition and the current medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the second preset working condition do not meet the second preset condition, reducing the rated load of the machine set of the first preset working condition and the second preset working condition to obtain a new first preset working condition and a new second preset working condition, and jumping to the step of acquiring a third operation parameter corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system under the current first preset working condition and a fourth operation parameter corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system under the current second preset working condition until the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current first preset working condition and the second preset working condition meet the second preset condition when the leakage test valve is in the full-open state.

In one possible implementation manner, the calculating the steam leakage rate of the intermediate shaft seal of the high-medium pressure cylinder according to the fifth operation parameter includes:

assigning the intermediate shaft seal steam leakage rate of the high-medium pressure cylinder as a preset shaft seal steam leakage rate;

calculating the medium pressure cylinder through-flow efficiency when the leakage test valve is in a fully closed state under a second preset working condition according to the fifth operation parameter and the current preset shaft seal steam leakage rate;

and when the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in a full-open state under the second preset working condition and the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in a full-closed state under the second preset working condition meet a third preset condition, determining that the preset shaft seal steam leakage rate is the middle shaft seal steam leakage rate of the high and medium pressure cylinders.

In one possible implementation manner, the calculating, according to the fifth operation parameter and the current preset shaft seal steam leakage rate, the medium pressure cylinder flow efficiency when the leak test valve is in the fully closed state under the second preset working condition includes:

calculating the steam inlet enthalpy value of the medium pressure cylinder when the leakage test valve is in a fully closed state under a second preset working condition according to the fifth operation parameter and the current preset shaft seal steam leakage rate;

Calculating the steam inlet temperature of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition according to the steam inlet enthalpy value and the front steam pressure of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition;

and calculating the medium pressure cylinder through-flow efficiency when the leakage test valve is in the fully closed state under the second preset working condition according to the vapor inlet enthalpy value before the medium pressure cylinder vapor inlet valve, the medium pressure cylinder vapor inlet temperature and the fifth operation parameter when the leakage test valve is in the fully closed state under the second preset working condition.

In one possible implementation, the method further includes:

when the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-closed state under the second preset working condition do not meet a third preset condition, assigning the high and medium pressure cylinder intermediate shaft seal steam leakage rate to be a new preset shaft seal steam leakage rate, and calculating according to the fifth operation parameter and the current preset shaft seal steam leakage rate until the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-closed state under the second preset working condition meet the third preset condition, and determining the new shaft seal steam leakage rate to be the high and medium pressure cylinder intermediate shaft seal steam leakage rate.

In one possible implementation, the fifth operating parameter includes: the high-pressure cylinder is regulated to be steam after stage when the leakage test valve is in the fully closed state under the second preset working conditionPressure P _cst ^VC And steam temperature t _cst ^VC Front steam pressure P of steam inlet valve of medium pressure cylinder _IPin1d ^VC And steam temperature t _IPin1d ^VC Steam pressure P of medium-low pressure communication pipeline in middle pressure cylinder outlet _IPexhd ^VC And steam temperature t _IPexht ^VC ；

According to the fifth operation parameter and the current preset shaft seal steam leakage rate, calculating a medium pressure cylinder steam inlet enthalpy value when the leakage test valve is in a fully closed state under a second preset working condition, including:

according toCalculating the vapor inlet enthalpy value of the medium pressure cylinder when the leakage test valve is in the fully closed state under a second preset working condition;

wherein h is _IPin3d ^VC Representing the vapor inlet enthalpy value R of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition _l Representing a preset shaft seal steam leakage rate;

according to the steam inlet enthalpy value and the steam pressure before the medium pressure cylinder steam inlet valve when the leakage test valve is in the fully closed state under a second preset working condition, calculating the medium pressure cylinder steam inlet temperature when the leakage test valve is in the fully closed state under the second preset working condition, including:

according toCalculating the steam inlet temperature of the medium-pressure cylinder when the leakage test valve is in a fully closed state under the second preset working condition;

Wherein P is _IPin3d ^VC Representing the steam inlet pressure of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition, and t _IPin3t ^VC Representing the steam inlet temperature of the medium-pressure cylinder when the leakage test valve is in a fully closed state under the second preset working condition;

according to the vapor inlet enthalpy value before the vapor inlet valve of the medium pressure cylinder, the vapor inlet temperature of the medium pressure cylinder and the fifth operation parameter when the leakage test valve is in the fully closed state under the second preset working condition, the calculation of the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition comprises the following steps:

according toCalculating the medium pressure cylinder through-flow efficiency when the leakage test valve is in a fully closed state under a second preset working condition;

wherein eta _IP ^VC And (3) representing the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in the fully closed state under a second preset working condition, wherein spt (P, t) represents a steam-water characteristic function for solving the medium entropy value according to the medium pressure and the temperature, and hps (P, s) represents a steam-water characteristic function for solving the medium enthalpy value according to the medium pressure and the entropy value.

The embodiment of the invention provides a high-medium pressure cylinder intermediate shaft seal steam leakage rate test system and a calculation method, wherein a leakage branch pipeline is additionally arranged on a high-medium pressure cylinder intermediate shaft seal leakage channel, a leakage test valve is arranged on the leakage branch pipeline, and system operation parameters in the full-open state and the full-closed state of the leakage test valve are obtained under different load states, so that the shaft seal steam leakage rate of the high-medium pressure cylinder intermediate shaft seal leakage channel can be calculated according to the operation parameters, the problem that the state of the steam turbine high-medium pressure cylinder intermediate shaft seal steam leakage cannot be accurately monitored in the prior art is solved, and accurate reference data is provided for maintenance of a turbine body.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a system for testing the leakage rate of an intermediate shaft seal of a high-and-medium pressure cylinder, which is provided by the embodiment of the invention;

FIG. 2 is a flowchart of an implementation of a method for calculating the steam leakage rate of an intermediate shaft seal of a high-medium pressure cylinder, which is provided by the embodiment of the invention;

FIG. 3 is a flowchart of an implementation of a method for calculating a steam leakage rate of an intermediate shaft seal of a high-and-medium pressure cylinder according to another embodiment of the present invention;

fig. 4 is a flowchart of an implementation of calculating a shaft seal steam leakage rate according to an embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth such as the particular system architecture, techniques, etc., in order to provide a thorough understanding of the embodiments of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the following description will be made by way of specific embodiments with reference to the accompanying drawings.

Fig. 1 is a schematic system diagram of a system for testing a leakage rate of an intermediate shaft seal of a high-medium pressure cylinder according to an embodiment of the present invention, including: a leakage branch pipeline 1, a leakage test valve 2 and a condenser 3;

the steam inlet end of the leakage branch pipeline 1 is connected to a middle shaft seal leakage channel 4 of the high-medium pressure cylinder, and the steam outlet end of the leakage branch pipeline 1 is connected to a condenser 3; an n-level shaft seal is arranged on the middle shaft seal leakage channel 4 of the high-medium pressure cylinder, and a leakage branch pipeline 1 reaching the condenser 3 is connected to an m-level shaft seal along the flowing direction of leakage steam, wherein n and m are positive integers, and m is smaller than n;

a leak test valve 2 is provided on the leak branch line 1.

The intermediate shaft seal steam leakage rate test system of the high and medium pressure cylinders further comprises: a high pressure cylinder pressure stage 5, a high pressure cylinder regulating stage 6, a boiler superheater 7, a medium pressure cylinder 8, a boiler reheater 9 and a steam inlet valve 10;

the steam inlet of the high-pressure cylinder pressure stage 5 is communicated with the outlet of the high-pressure cylinder regulating stage 6, and the steam inlet of the high-pressure cylinder regulating stage 6 is connected with the steam outlet of the boiler superheater 7 through a pipeline;

the steam inlet of the medium pressure cylinder 8 is connected with the steam outlet of the boiler reheater 9 through a pipeline; a steam inlet valve 10 is arranged on a pipeline between the intermediate pressure cylinder 8 and the boiler reheater 9 for regulating steam entering the intermediate pressure cylinder 8;

The high-pressure steam inlet end of the high-medium pressure cylinder intermediate shaft seal steam leakage channel 4 is communicated with the outlet of the high-pressure cylinder adjusting stage 6, and the steam outlet end is communicated with the steam inlet end of the rear and medium pressure cylinders 8 of the steam inlet valve 10;

referring to fig. 1, the direction of the arrow indicates the direction of the steam flow. In fig. 1, the steam outlet of the high pressure cylinder 5 is connected to the reheater, and the steam outlet of the medium pressure cylinder 8 is also connected to the medium pressure cylinder outlet medium and low pressure communication pipe 11.

The steam turbine is respectively provided with a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder according to the working characteristics. The high-pressure cylinder is the initial stage of main steam entering the cylinder, and the steam pressure is high and the temperature is high at this time, so that the corresponding high-pressure cylinder blade is short and the impeller diameter is large. The intermediate pressure cylinder is the second cylinder in the turbine that receives steam and is typically designed as a medium diameter cylinder, where the steam pressure is lower in the higher pressure cylinders and higher in the lower pressure cylinders. The high pressure cylinder, the medium pressure cylinder and the low pressure cylinder are arranged in parallel and are different in internal pressure.

The turbine stage can be divided into an adjusting stage and a non-adjusting stage, wherein the adjusting stage refers to a first working stage of the turbine, and the flow area of the turbine can be changed along with the load change due to the fact that part of inlet steam can be changed, so that the adjusting effect is achieved. The unregulated stage may also be referred to as a pressure stage, with the exception of the regulated stage, being the pressure stage.

According to the high-medium pressure cylinder middle shaft seal steam leakage rate test system, the leakage branch pipeline is additionally arranged on the high-medium pressure cylinder middle shaft seal leakage channel in the middle of the high-medium pressure cylinder and the medium pressure cylinder, the leakage test valve is arranged on the leakage branch pipeline, and when the high-medium pressure cylinder middle shaft seal steam leakage rate test system is in operation, the shaft seal steam leakage rate of the high-medium pressure cylinder middle shaft seal leakage channel can be conveniently and rapidly calculated by acquiring the operation data of the leakage test valve in the full-open state and the full-closed state, so that the problem that the state of shaft seal steam leakage of the high-medium pressure cylinder middle shaft seal leakage channel of the steam turbine cannot be accurately monitored in the prior art is solved, and accurate reference data are provided for maintenance of a steam turbine body.

Fig. 2 is a flowchart of an implementation of a method for calculating a steam leakage rate of an intermediate shaft seal of a high and medium pressure cylinder according to an embodiment of the present invention, and the method for calculating the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinder by applying the system for testing the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinder shown in fig. 1 is detailed as follows:

step 201, obtaining a first operation parameter in a high and medium pressure cylinder intermediate shaft seal steam leakage rate test system when a leakage test valve is in a full-open state under a rated working condition.

The leakage test valve is arranged in the high-medium pressure cylinder intermediate shaft seal leakage rate test system, and the sizes of the leakage test valves are different, so that in order to determine that the leakage test valve arranged in the high-medium pressure cylinder intermediate shaft seal leakage rate test system is a proper leakage test valve, the steam through flow passing through the leakage test valve needs to be calculated under the rated working condition at first, and whether the leakage test valve is proper or not is determined according to the steam through flow passing through the leakage test valve.

Optionally, the first operation parameter may include an operation parameter of the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system and a parameter of the leakage test valve, wherein the operation parameter of the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system may include: steam pressure P after regulating stage of high-pressure cylinder _csd And steam temperature t _csd Steam pressure P before steam inlet valve of medium pressure cylinder _IPin1d The pressure loss PS is designed for a steam inlet valve of the medium pressure cylinder; parameters of the leak test valve may include: critical pressure drop ratio x of leak test valve _T Valve flow coefficient K _v 。

Referring to fig. 1, the high pressure cylinder regulates post-stage vapor pressure P _csd For the steam pressure at point a in fig. 1, the high pressure cylinder regulates the post-stage steam temperature t _csd Is the steam temperature at point a in fig. 1.

Steam pressure P before steam inlet valve of medium pressure cylinder _IPin1d Is the vapor pressure at point B in fig. 1.

According to the type of the leakage test valve, parameters such as critical pressure drop ratio, valve flow coefficient, inner diameter of the connecting pipeline and the like according to the leakage test valve can be inquired and obtained from manufacturer data.

Step 202, calculating the steam through-flow through the leak test valve based on the first operating parameter.

After obtaining the first operation parameter, calculating the steam through-flow through the leak test valve according to the first operation parameter may include:

Firstly, according to the steam pressure P before the steam inlet valve of the medium pressure cylinder _IPin1d And the design pressure loss PS of the steam inlet valve of the medium pressure cylinder is used for calculating the steam inlet pressure of the medium pressure cylinder when the leakage test valve is in a full-open state under the rated working condition, namely calculating the steam inlet pressure at the position of the C point in the graph 1.

Alternatively, according toCalculating the steam inlet pressure of the medium pressure cylinder when the leakage test valve is in a full-open state under the rated working condition; wherein P is _IPin3d And the gas inlet pressure of the medium pressure cylinder when the leakage test valve is in the full-open state under the rated working condition is represented.

Then according to the steam inlet pressure P of the medium pressure cylinder when the leakage test valve is in the full-open state under the rated working condition _IPin3d And the steam pressure P after the high-pressure cylinder regulating stage _csd And calculating the steam pressure at the inlet position of the leakage branch pipeline when the leakage test valve is in the full-open state under the rated working condition.

Alternatively, according toCalculating the steam pressure at the inlet position of the leakage branch pipeline when the leakage test valve is in the full-open state under the rated working condition; wherein P is _vind The steam pressure of the inlet position of the leakage branch pipeline when the leakage test valve is in the full open state under the rated working condition is represented, n represents the total number of shaft seal stages arranged on the middle shaft seal steam leakage channel of the high and medium pressure cylinder, m represents the number of shaft seal stages of the leakage branch pipeline connected to the upper stream of the middle shaft seal steam leakage channel of the high and medium pressure cylinder, and the number of shaft seal stages is counted along the flow direction of the shaft seal leakage steam, and the leakage is arranged before the (m+1) th stage shaft seal after the number of shaft seals is counted from left to right to the mth stage shaft seal according to the arrow direction on the middle shaft seal steam leakage channel of the high and medium pressure cylinder as shown in the figure 1 And a branch pipeline.

Then according to the steam pressure P after the high-pressure cylinder is regulated when the leakage test valve is in the full-open state under the rated working condition _csd And steam temperature t _csd Steam pressure P at the inlet of the leakage branch line _vind Calculating the steam temperature of the inlet position of the leakage branch pipeline when the leakage test valve is in the full-open state under the rated working condition;

alternatively, according to t _vind ＝tph[P _vind ,hpt(P _csd ,t _csd )]Calculating the steam temperature of the inlet position of the leakage branch pipeline when the leakage test valve is in the full-open state under the rated working condition; wherein t is _vind The steam temperature of the inlet position of the leakage branch pipeline when the leakage test valve is in the full-open state under the rated working condition is represented, hpt (P, t) is a steam-water characteristic function for solving the enthalpy value of the medium according to the pressure and the temperature of the medium, and tph (P, h) is a steam-water characteristic function for solving the enthalpy value of the medium according to the pressure and the enthalpy value of the medium.

Finally, according to the critical pressure drop ratio x of the leakage test valve _T Valve flow coefficient K _v Steam pressure P at inlet position of leakage branch pipeline when leakage test valve is in full open state under rated working condition _vind And steam temperature t of leakage branch line _vind Calculating the steam through-flow rate passing through the leakage test valve;

alternatively, according toCalculating the steam through-flow rate passing through the leakage test valve;

Wherein Cppt (P, t) represents a steam-water characteristic function for solving the specific heat of the medium at a constant pressure according to the medium pressure and the temperature, cvpt (P, t) represents a steam-water characteristic function for solving the specific heat of the medium at a constant pressure according to the medium pressure and the temperature, and vpt (P, t) represents a steam-water characteristic function for solving the specific heat of the medium according to the medium pressure and the temperature.

And 203, when the steam through-flow rate meets the first preset condition, acquiring second operation parameters corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system when the leakage test valve is in a full-open or full-closed state under different preset working conditions, and calculating the high and medium pressure cylinder intermediate shaft seal steam leakage rate according to the second operation parameters.

As shown in fig. 3, before this step, the method further includes:

detecting whether the steam through-flow meets a first preset condition;

when the steam through-flow rate meets the first preset condition, executing step 203; when the steam through flow does not meet the first preset condition, the size of the leakage test valve is increased, the leakage test valve is replaced, the replaced new leakage test valve is installed on a leakage branch pipeline of the intermediate shaft seal leakage rate test system of the high-medium pressure cylinder, and the process jumps to the step 201 to be executed again until the steam through flow meets the first preset condition.

In an embodiment, detecting whether the steam through-flow rate meets the first preset condition may include: detecting whether the flow of the steam through flow is larger than a preset multiple of the design leakage flow of the intermediate shaft seal of the high-medium pressure cylinder; if the steam through-flow is larger than the preset multiple of the leakage flow designed by the intermediate shaft seal of the high-medium pressure cylinder, determining that the steam through-flow meets a first preset condition, otherwise, the steam through-flow does not meet the first preset condition.

Here, the preset multiple may be set according to the requirement, for example, the preset multiple may be 1.5 times, and in this embodiment, the value of the preset multiple is not limited.

Optionally, referring to fig. 4, obtaining second operation parameters corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system when the leakage test valve is in a fully opened or fully closed state under different preset working conditions, and calculating the high and medium pressure cylinder intermediate shaft seal steam leakage rate according to the second operation parameters may include the following steps:

and step 401, when the leakage test valve is in a fully-opened state, acquiring a third operation parameter corresponding to the high and medium pressure cylinder intermediate shaft seal leakage rate test system under the current first preset working condition and a fourth operation parameter corresponding to the high and medium pressure cylinder intermediate shaft seal leakage rate test system under the current second preset working condition.

The first preset working condition is different from the second preset working condition, but it is noted that the rated load of the unit in the first preset working condition is different from the rated load of the unit in the second preset working condition by more than 15%, otherwise, the rated load or the output of the unit in the two preset working conditions are close, so that the calculated through-flow efficiency of the medium-pressure cylinder does not meet the condition. In an embodiment, the first preset working condition may be a 50% rated load state, the second preset working condition may be a 75% rated load state, and the calculating mode adopted in calculating the through-flow efficiency of the medium pressure cylinder is the same, so that under different working conditions, the types of the measured third operating parameter and the measured fourth operating parameter are the same, but the obtained values are different.

The third operating parameter may include: the steam pressure P before the steam inlet valve of the medium pressure cylinder when the leak test valve is in the full open state under the first preset working condition _IPin1d ' and steam temperature t _IPin1t Steam pressure P of medium-low pressure communication pipe at outlet of medium-pressure cylinder _IPexhd ' and steam temperature t _IPexht '。

Front steam pressure P of steam inlet valve of medium pressure cylinder _IPin1d ' and steam temperature t _IPin1t ' i.e. the steam pressure and steam temperature at 50% of rated load at point B in fig. 1. Pressure P of middle-low pressure communication pipe in middle-pressure cylinder outlet _IPexhd ' sum temperature t _IPexht ' i.e. the steam pressure and steam temperature of the low pressure communication pipe 11 in the medium pressure cylinder outlet in fig. 1.

Step 402, calculating the current medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the first preset working condition according to the third operation parameter.

After the third operation parameter is measured, calculating the current medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the first preset working condition may include:

firstly, according to the front steam pressure P of a steam inlet valve of a medium pressure cylinder when a leakage test valve is in a full-open state under the current first preset working condition _IPin1d And calculating the pressure loss of the design of the middle pressure cylinder steam inlet valve and the steam inlet pressure of the middle pressure cylinder when the leakage test valve is in a full-open state under the current first preset working condition.

Alternatively, according toCalculate the current firstThe method comprises the steps that when a leakage test valve is in a full-open state under a preset working condition, the steam inlet pressure of a medium pressure cylinder is increased; wherein P is _IPin3d ' represents the pressure of the inlet steam of the medium pressure cylinder when the leakage test valve is in the full-open state under the current first preset working condition.

Then according to the current front steam pressure P of the steam inlet valve of the medium pressure cylinder when the leak test valve is in the full-open state under the first preset working condition _IPin1d ' and steam temperature t _IPin1t ' steam inlet pressure P of medium pressure cylinder _IPin3d And', calculating the steam inlet temperature of the medium pressure cylinder when the leakage test valve is in the full-open state under the current first preset working condition, namely calculating the steam inlet temperature of the C point position in the graph 1.

Alternatively, according to t _IPin3t '＝tph[P _IPin3d ',hpt(P _IPin1d ',t _IPin1t ')]Calculating the steam inlet temperature of the medium pressure cylinder when the leakage test valve is in the full-open state under the current first preset working condition, wherein t _IPin3t ' represents the steam inlet temperature of the medium pressure cylinder when the leakage test valve is in the full-open state under the current first preset working condition, hpt (P, t) is a steam-water characteristic function for solving the enthalpy value of the medium according to the pressure and the temperature of the medium, and tph (P, h) is a steam-water characteristic function for solving the enthalpy value of the medium according to the pressure and the enthalpy value of the medium.

Finally, according to the front steam pressure P of the steam inlet valve of the medium pressure cylinder when the leakage test valve is in the full-open state under the current first preset working condition _IPin1d ' and steam temperature t _IPin1t ' Medium pressure cylinder steam inlet temperature P _IPin3d ' and steam inlet temperature t _IPin3t ' Medium-low pressure communication pipe steam pressure P in medium-pressure cylinder outlet _IPexhd ' and steam temperature t _IPexht ' calculating the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in the full-open state under the current first preset working condition;

alternatively, according to

Calculating the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in a full-open state under the current first preset working condition; wherein eta is _IP ' represents the medium pressure cylinder through-flow efficiency when the leak test valve is in the fully open state under the current first preset working conditionSpt (P, t) represents a steam-water characteristic function for solving the medium entropy value according to the medium pressure and the temperature, and hps (P, s) represents a steam-water characteristic function for solving the medium enthalpy value according to the medium pressure and the entropy value.

And step 403, calculating the current medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the second preset working condition according to the fourth operation parameter.

The calculation method of the through-flow efficiency of the medium pressure cylinder in the current second preset condition is the same as that of the leakage test valve in the step 402, and only the adopted operation parameters are different, so that the detailed description is not repeated here.

And step 404, if the current through-flow efficiency of the middle pressure cylinder when the leakage test valve is in the full-open state under the first preset working condition and the current through-flow efficiency of the middle pressure cylinder when the leakage test valve is in the full-open state under the second preset working condition meet the second preset condition, acquiring a fifth operation parameter corresponding to the high and middle pressure cylinder middle shaft seal leakage rate test system when the leakage test valve is in the full-closed state under the second preset working condition.

In one embodiment, as shown in fig. 3, after step 403, before step 404, the method further includes: detecting whether the medium pressure cylinder through-flow efficiency when the leakage test valve is in a full-open state under the current first preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current second preset working condition meet the second preset condition; when the leakage test valve is in the fully opened state, step 404 is executed, and when the set rated loads of the first preset working condition and the second preset working condition are not met, the steps of obtaining the new first preset working condition and the new second preset working condition, and jumping to the step of obtaining the third operation parameter corresponding to the middle shaft seal leakage rate test system of the high and middle pressure cylinder under the current first preset working condition and the fourth operation parameter corresponding to the middle shaft seal leakage rate test system of the high and middle pressure cylinder under the current second preset working condition until the through-flow efficiency of the middle pressure cylinder when the leakage test valve is in the fully opened state under the current first preset working condition and the through-flow efficiency of the middle pressure cylinder when the leakage test valve is in the fully opened state under the current second preset working condition meet the second preset condition are carried out.

When the rated load of the unit is reduced by 50% and the rated load of the unit is reduced by 75%, the actual leakage quantity of the intermediate shaft seal leakage channel of the high-pressure cylinder can be reduced, so that the through-flow efficiency of the medium-pressure cylinder meets a second preset condition.

Alternatively, the unit 50% rated load and the unit 75% rated load are reduced, and the new first preset working condition obtained may be 45% rated load and 60% rated load.

In an embodiment, detecting whether the current medium pressure cylinder flow efficiency when the leak test valve is in the fully opened state under the first preset working condition and the current medium pressure cylinder flow efficiency when the leak test valve is in the fully opened state under the second preset working condition meet the second preset condition may include:

detecting whether the absolute value of the difference value between the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current first preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current second preset working condition is smaller than a preset value; if the absolute value of the difference between the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current first preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current second preset working condition is smaller than the preset value, determining that the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current first preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current second preset working condition meet the second preset condition, otherwise, determining that the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current first preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the current second preset working condition do not meet the second preset condition.

The preset value may be set according to the requirement, and is not limited in this embodiment, and may be a fixed value of 0.1%, for example.

In one embodiment, the fifth operating parameter may include: steam pressure P after the high pressure cylinder adjusts the stage when the leak test valve is in the fully closed state under the second preset working condition _cst ^VC And steam temperatureDegree t _cst ^VC Front steam pressure P of steam inlet valve of medium pressure cylinder _IPin1d ^VC And steam temperature t _IPin1d ^VC Steam pressure P of medium-low pressure communication pipeline in middle pressure cylinder outlet _IPexhd ^VC And steam temperature t _IPexht ^VC 。

And step 405, calculating the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinders according to the fifth operation parameters.

In an embodiment, calculating the shaft seal leakage rate of the shaft seal leakage pipe between the high pressure cylinder and the medium pressure cylinder according to the fifth operation parameter may include:

assigning the intermediate shaft seal steam leakage rate of the high-medium pressure cylinder as a preset shaft seal steam leakage rate; in this embodiment, we first assume a preset shaft seal steam leakage rate, then verify, and when verification fails, again assume a shaft seal steam leakage rate, and when verification succeeds, the assumed shaft seal steam leakage rate is the required intermediate shaft seal steam leakage rate of the high-medium pressure cylinder. The intermediate shaft seal leakage rate of the high and medium pressure cylinders is the shaft seal leakage rate of the intermediate shaft seal leakage channel of the high and medium pressure cylinders.

Calculating the medium pressure cylinder through-flow efficiency when the leakage test valve is in the fully closed state under the second preset working condition according to the fifth operation parameter and the current preset shaft seal steam leakage rate;

and when the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in the full-open state under the second preset working condition and the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in the full-closed state under the second preset working condition meet the third preset condition, determining that the preset shaft seal steam leakage rate is the middle shaft seal steam leakage rate of the high and medium pressure cylinders.

In an embodiment, calculating the medium pressure cylinder through-flow efficiency when the leak test valve is in the fully closed state under the second preset working condition according to the fifth operation parameter and the current preset shaft seal leak rate may include:

calculating the vapor inlet enthalpy value of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition according to the fifth operation parameter and the current preset shaft seal vapor leakage rate;

calculating the medium pressure cylinder steam inlet temperature when the leakage test valve is in the fully closed state under the second preset working condition according to the medium pressure cylinder steam inlet enthalpy value and the medium pressure cylinder steam inlet valve front steam pressure when the leakage test valve is in the fully closed state under the second preset working condition;

Optionally, calculating the vapor inlet enthalpy value of the intermediate pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition according to the fifth operation parameter and the current preset shaft seal vapor leakage rate may include: according to the steam pressure P after the high-pressure cylinder is regulated when the leakage test valve is in the fully closed state under the second preset working condition _cst ^VC And steam temperature t _cst ^VC Front steam pressure P of steam inlet valve of medium pressure cylinder _IPin1d ^VC And steam temperature t _IPin1d ^VC Preset shaft seal steam leakage rate R _l And calculating the vapor inlet enthalpy value of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition.

Alternatively, according toCalculating the vapor inlet enthalpy value of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition;

wherein h is _IPin3d ^VC Representing the vapor inlet enthalpy value R of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition _l Indicating the preset shaft seal steam leakage rate.

In an embodiment, calculating the medium pressure cylinder steam inlet temperature when the leak test valve is in the fully closed state under the second preset working condition according to the medium pressure cylinder steam inlet enthalpy value and the medium pressure cylinder steam inlet valve front steam pressure when the leak test valve is in the fully closed state under the second preset working condition may include: according to the front steam pressure P of the steam inlet valve of the medium pressure cylinder when the leak test valve is in the fully closed state under the second preset working condition _IPin1d ^VC Calculating the steam inlet pressure P of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition _IPin3d ^VC The method comprises the steps of carrying out a first treatment on the surface of the According toThe steam inlet pressure P of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition _IPin3d ^VC And the vapor inlet enthalpy value h of the medium pressure cylinder _IPin3d ^VC Calculating the steam inlet temperature t of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition _IPin3t ^VC 。

Alternatively, according toAnd calculating the steam inlet temperature of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition.

In one embodiment, the fifth operating parameter further comprises: steam pressure P of medium-low pressure communication pipeline in outlet of medium-pressure cylinder _IPexhd ^VC And steam temperature t _IPexht ^VC ；

According to the vapor inlet enthalpy value h before the vapor inlet valve of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition _IPin3d ^VC Steam inlet temperature t of medium-pressure cylinder _IPin3t ^VC And fifth operation parameters, calculating the medium pressure cylinder through-flow efficiency eta when the leakage test valve is in the fully closed state under the second preset working condition _IP ^VC The fifth operating parameter can be the steam pressure P of the medium-pressure cylinder outlet medium-low pressure communication pipeline _IPexhd ^VC And steam temperature t _IPexht ^VC May include:

alternatively, according toCalculating the medium pressure cylinder through-flow efficiency when the leakage test valve is in the fully closed state under the second preset working condition; wherein eta _IP ^VC The leakage test valve is in the full-closed state under the second preset working condition, spt (P, t) represents the steam-water characteristic function for solving the medium entropy value according to the medium pressure and the temperature, and hps (P, s) represents the steam-water characteristic function for solving the medium enthalpy value according to the medium pressure and the entropy value.

After the medium pressure cylinder through-flow efficiency when the leakage test valve is in the fully closed state under the second preset working condition is obtained through calculation, detecting whether the medium pressure cylinder through-flow efficiency when the leakage test valve is in the fully open state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the fully closed state under the second preset working condition meet a third preset condition;

When the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-closed state under the second preset working condition do not meet the third preset condition, the intermediate shaft seal leakage rate of the high and medium pressure cylinders is assigned to be a new preset shaft seal leakage rate, calculation is carried out according to the fifth operation parameter and the current preset shaft seal leakage rate until the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the second preset working condition and the intermediate pressure cylinder through-flow efficiency when the leakage test valve is in the full-closed state under the second preset working condition meet the third preset condition, and the new shaft seal leakage rate is determined to be the intermediate shaft seal leakage rate of the high and medium pressure cylinders.

Here, detecting whether the medium pressure cylinder through-flow efficiency when the leak test valve is in the fully-opened state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leak test valve is in the fully-closed state under the second preset working condition meet the third preset condition may include: detecting whether the absolute value of the difference between the medium pressure cylinder through-flow efficiency when the leak test valve is in the full-open state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leak test valve is in the full-closed state under the second preset working condition is smaller than a preset value, and determining that the medium pressure cylinder through-flow efficiency when the leak test valve is in the full-open state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leak test valve is in the full-closed state under the second preset working condition meet a third preset condition when the absolute value of the difference between the medium pressure cylinder through-flow efficiency when the leak test valve is in the full-open state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leak test valve is in the full-closed state under the second preset working condition is smaller than a preset value; otherwise, determining that the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-open state under the second preset working condition and the medium pressure cylinder through-flow efficiency when the leakage test valve is in the full-closed state under the second preset working condition do not meet the third preset condition.

The preset value here may be 0.1%.

According to the embodiment of the invention, the first operation parameter in the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system is obtained when the leakage test valve is in the full-open state under the rated working condition; according to the first operation parameter, calculating the steam through-flow rate passing through the leakage test valve; when the steam through-flow meets the first preset condition, acquiring second operation parameters corresponding to the high and medium pressure cylinder intermediate shaft seal steam leakage rate test system when the leakage test valve is in the full-open or full-closed state under different preset working conditions, and calculating the high and medium pressure cylinder intermediate shaft seal steam leakage rate according to the second operation parameters, so that the high and medium pressure cylinder intermediate shaft seal steam leakage rate can be accurately and efficiently calculated according to the measured operation parameters of the steam turbine under the full-open and full-closed states of the leakage test valve under different load states, and the problem that the high and medium pressure cylinder intermediate shaft seal steam leakage rate cannot be efficiently and accurately monitored due to large field test adjustment workload when the high and medium pressure cylinder intermediate shaft seal steam leakage rate is determined by adopting test modes such as variable steam temperature in the prior art is solved.

It should be understood that the sequence number of each step in the foregoing embodiment does not mean that the execution sequence of each process should be determined by the function and the internal logic, and should not limit the implementation process of the embodiment of the present invention.

The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention.

Claims

1. The utility model provides a high intermediate pressure jar intermediate shaft seal steam leakage rate test system which characterized in that includes: a leakage branch pipeline, a leakage test valve and a condenser;

the leak test valve is disposed on the leak branch line.

2. The method for calculating the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinder is characterized by comprising the following steps of:

3. The method for calculating the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to claim 2, wherein the first operation parameters include: critical pressure drop ratio x of the leak test valve _T Valve flow coefficient K _v And the steam pressure P after the high-pressure cylinder adjusts the stage when the leakage test valve is in the full-open state under the rated working condition _csd And steam temperature t _csd Steam pressure P before steam inlet valve of medium pressure cylinder _IPin1d The pressure loss PS is designed for a steam inlet valve of the medium pressure cylinder;

wherein W is _d Represents the flow rate of the steam through the leak test valve, P _IPin3d Represents the steam inlet pressure, P, of the medium pressure cylinder when the leakage test valve is in the full-open state under the rated working condition _vind The steam pressure of the inlet position of the leakage branch pipeline when the leakage test valve is in the full open state under the rated working condition is represented, n represents the total number of shaft seal stages arranged on a middle shaft seal leakage steam channel of the high-medium pressure cylinder, m represents the number of shaft seal stages (counted along the flow direction of shaft seal leakage steam) of the leakage branch pipeline connected to the position upstream of the middle shaft seal leakage steam channel of the high-medium pressure cylinder, and t represents the number of shaft seal stages _vind The steam temperature of the inlet position of the leakage branch pipeline when the leakage test valve is in the full-open state under the rated working condition is represented, wherein hpt (P, t) is steam for solving the enthalpy value of the medium according to the pressure and the temperature of the mediumThe water characteristic function, tph (P, h), is a steam-water characteristic function for solving the enthalpy value of the medium according to the pressure and the enthalpy value of the medium, cppt (P, t) is a steam-water characteristic function for solving the specific heat of the constant pressure of the medium according to the pressure and the temperature of the medium, cvpt (P, t) is a steam-water characteristic function for solving the specific heat of the constant volume of the medium according to the pressure and the temperature of the medium, and vpt (P, t) is a steam-water characteristic function for solving the specific volume of the medium according to the pressure and the temperature of the medium.

4. The method for calculating the leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to claim 2, wherein the judging that the steam through-flow rate meets the first preset condition comprises:

5. The method for calculating the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to claim 2, wherein the second operation parameters comprise a third operation parameter, a fourth operation parameter and a fifth operation parameter;

6. The method for calculating the steam leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to claim 5, further comprising:

7. The method for calculating the leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to claim 5, wherein calculating the leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to the fifth operation parameter comprises:

8. The method for calculating the leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to claim 7, wherein calculating the through-flow efficiency of the medium pressure cylinder when the leakage test valve is in the fully closed state under the second preset working condition according to the fifth operation parameter and the current preset shaft seal leakage rate comprises:

9. The method for calculating the leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to claim 7, further comprising:

10. The method for calculating the leakage rate of the intermediate shaft seal of the high and medium pressure cylinder according to claim 8, wherein the fifth operation parameters include: steam pressure P after the high-pressure cylinder is regulated when the leakage test valve is in a fully closed state under a second preset working condition _cst ^VC And steam temperature t _cst ^VC Front steam pressure P of steam inlet valve of medium pressure cylinder _IPin1d ^VC And steam temperature t _IPin1d ^VC Steam pressure P of medium-low pressure communication pipeline in middle pressure cylinder outlet _IPexhd ^VC And steam temperature t _IPexht ^VC ；

wherein eta _IP ^VC Indicating the medium pressure cylinder through-flow efficiency when the leakage test valve is in the fully closed state under the second preset working condition, wherein spt (P, t) represents a steam-water characteristic function for solving the medium entropy value according to the medium pressure and the temperature, and hps (P, s) represents a control valve according to the medium pressure and the temperatureThe medium pressure and the entropy value solve the steam-water characteristic function of the medium enthalpy value.