CN114790920A - Method for calculating overpressure state of high-temperature reheat steam pipeline in real time - Google Patents

Abstract

The invention discloses a method for calculating the overpressure state of a high-temperature reheating steam pipeline in real time, which comprises the following steps of; 1) acquiring reheat steam pressure RHP of each reheat steam pressure measuring point on high-temperature reheat steam pipeline of unit _i (ii) a 2) Obtaining the generated power at the previous moment t _now‑1 Real-time generated power P _e (t _now‑1 ) And current time t _now Real-time generated power P _e (t _now ) Judging whether the unit operates normally or not, and if the unit operates normally and continuously, turning to the step 3), otherwise, turning to the step 1); 3) confirming the current time t _now Acquiring the reheat steam pressure RHP of all reheat steam pressure measuring points in the single complete overpressure process _i (t) calculating an accumulated overpressure state value S of the high-temperature reheat steam pipeline up to the calculation time, and representing the overpressure state of the high-temperature reheat steam pipeline through the accumulated overpressure state value S of the high-temperature reheat steam pipeline up to the calculation timeThe overpressure condition of the high-temperature reheat steam line can be calculated in real time.

Description

A method for real-time calculation of overpressure state of high temperature reheat steam pipeline

technical field

The invention belongs to the technical field of thermal power generation industry, and particularly relates to a method for calculating the overpressure state of a high-temperature reheat steam pipeline in real time.

Background technique

The reheat steam system of a thermal power plant is a general term for all the pipes and their ancillary components in the process of returning the steam that has done part of the work in the steam turbine to the boiler for reheating and returning to the steam turbine to do work. It is composed of the cold and high temperature reheat steam pipeline from the steam outlet of the steam turbine high pressure cylinder to the inlet of the boiler reheater, the high temperature reheat steam pipeline from the reheater outlet to the steam turbine medium pressure cylinder, the valve and the drain device. Among them, the high-temperature reheat steam pipeline is subjected to high-temperature and high-pressure service environment, especially many units put into operation around 2000 have been running for more than 100,000 hours, the material properties are deteriorated, and the operating conditions are harsh, and its safety is very important.

Although the design unit will give the appropriate design pressure, and the pipe specification will also consider the margin, during the service process, severe operating conditions and unstable factors will still cause the high-temperature reheated steam pipeline to operate under overpressure. Under the dual action of stress, it will not only accelerate the aging of the pipe material, but also cause stress concentration at the defect or cause the crack to expand at the crack, resulting in failure. The resulting probability of leakage or failure increases exponentially.

In addition, because the arrangement of the high-temperature reheat steam pipeline will pass near the centralized control room, once leakage or failure occurs, it will lead to a major safety accident of personal injury and death. Therefore, the real-time calculation of the overpressure state of the high-temperature reheat steam pipeline is very meaningful.

To this end, a method for real-time calculation of the overpressure state of the high temperature reheat steam pipeline is proposed, and the overpressure state value is used to reflect the actual overpressure state of the high temperature reheat steam pipeline, which is convenient for the operation and maintenance personnel to grasp the high temperature reheat steam pipeline. Health status to ensure the safety of the unit.

At present, in the published literature, only the literature reports that based on the finite element stress analysis method, the stress distribution at the weld of high temperature reheat steam pipeline is reasonably calculated. Optimization Analysis, 2021(37)"; there are also literature reports that the pressure drop of the 1000MW reheat steam system pipeline is optimized by using the American AFT fluid analysis and calculation software, and the best pipeline selection specifications are proposed, such as the literature "The main steam and Analysis of Pressure Drop in Reheat Steam System, 2017(28)”. However, there is no report on the method of real-time calculation of the overpressure state of the high temperature reheat steam pipeline.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, and to provide a real-time calculation method for the overpressure state of the high temperature reheat steam pipeline, which can calculate the overpressure state of the high temperature reheat steam pipeline in real time.

In order to achieve the above object, the method for calculating the overpressure state of a high temperature reheat steam pipeline in real time according to the present invention comprises the following steps:

1) obtain the reheat steam pressure RHP _i of each reheat steam pressure measuring point on the high temperature reheat steam pipeline of the unit;

2) Obtain the real-time generation power P _e (t _now-1 ) of the generation power at the previous time t _now-1 and the real-time generation power P _e (t _now ) at the current time t _now , and use this to judge that the unit is running and continues to run Whether it is normal, when the unit is running and continues to run, go to step 3), otherwise, go to step 1);

3) Determine the reheat steam pressure RHP _i (t _now-1 ) of each reheat steam pressure measuring point on the high temperature reheat steam pipeline of the unit at the previous time t _now-1 and the reheat steam pressure RHP at the current time t _{now i} (t _now ), and judge the overpressure state of the reheat steam pressure measurement point based on this, when the judgment result is no overpressure, starting overpressure or continuous overpressure, then go to step 1), when the judgment result is overpressure When the pressure is over, go to step 4);

4) Confirm the single complete overpressure process before the current time t _now , obtain the reheat steam pressure RHP _i (t) of all reheat steam pressure measurement points in the single complete overpressure process, and use this to calculate the high temperature reheat steam The accumulated overpressure state value S of the pipeline up to the calculation time, and the overpressure state of the high temperature reheat steam pipeline is represented by the accumulated overpressure state value S of the high temperature reheat steam pipeline up to the calculation time.

The specific operation of step 4) is:

41) Confirm the single complete overpressure process before the current time t _now , obtain the reheat steam pressure RHP _i (t) of all the reheat steam pressure measuring points in the single overpressure process, and use this to calculate the time before the current time t _now The single overpressure state value S _i (t) of each reheat steam pressure measuring point;

42) According to the single overpressure state value S _i (t) of each reheat steam pressure measurement point before the current time t _now , calculate the cumulative overpressure state value S _i of each reheat steam pressure measurement point up to the current time t _now ;

43) Calculate the accumulated overpressure state value S of the high temperature reheat steam pipeline as of the current time according to the accumulated overpressure state value S _i of each reheat steam pressure measurement point as of the current time _tnow .

When the conditions shown in formula (1) are satisfied, the unit is considered to be running and running continuously;

When the conditions shown in formula (2) are satisfied, it is considered that the reheat steam pressure measuring point is not overpressured;

if RHP _i (t _now-1 )<PA∨RHP _i (t _now )<PA (2).

When the conditions shown in formula (3) are satisfied, it is considered that the reheat steam pressure measurement point begins to overpressure;

if RHP _i (t _now-1 )<PA∨RHP _i (t _now )>=PA (3).

When the conditions shown in formula (4) are satisfied, the reheat steam pressure measurement point is considered to be continuously overpressured;

if RHP _i (t _now-1 )>=PA∨RHP _i (t _now )>=PA (4).

When the conditions shown in formula (5) are satisfied, it is considered that the overpressure of the reheat steam pressure measuring point is over;

if RHP _i (t _now-1 )>=PA∨RHP _i (t _now )<PA (5).

The single overpressure state value S _i (t) of each reheat steam pressure measurement point before the current time t _now :

Among them, t _start is the overpressure start time of a single overpressure process, and tend is the overpressure _end time of a single overpressure process.

The accumulated overpressure state value S _i of each reheat steam pressure measurement point up to the current time t _now :

Among them, t ₀ is the initial time of calculation, and t _now is the current time.

The accumulated overpressure state value S of the high temperature reheat steam pipeline up to the current time is:

S=max{S ₁ ,S ₂ ,S ₃ ...,S _i ...,S _n } (8)

Among them, i indicates that the high temperature reheat steam pipeline has n reheat steam pressure measuring points.

The present invention has the following beneficial effects:

The method for calculating the overpressure state of a high-temperature reheat steam pipeline in real time according to the present invention is, during specific operation, by obtaining the real-time power generation power value of the unit operating state parameter to judge the unit operation, and performing the overpressure measurement of each reheat steam pressure measurement point value in real time. According to the complete single overpressure process, the single overpressure state value is calculated in real time for each reheat steam pressure measurement point, and the cumulative overpressure is calculated in real time for each reheat steam pressure measurement point in time. Finally, based on multiple reheat steam pressure measurement points, the accumulated overpressure state value of the high temperature reheat steam pipeline is calculated in real time. The overpressure state of the high temperature reheat steam pipeline is characterized by the overpressure state value, which provides technical support for the power plant operation and maintenance technicians to carry out operation assessment and unit supervision.

Description of drawings

FIG. 1 is a flow chart of the present invention.

FIG. 2 is a diagram showing a single complete overpressure process before the current time t _now is confirmed.

Detailed ways

In order to make those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only The embodiments are part of the present invention, not all of the embodiments, and are not intended to limit the scope of the present disclosure. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The accompanying drawings show a schematic structural diagram of an embodiment according to the disclosure of the present invention. The figures are not to scale, some details have been exaggerated for clarity, and some details may have been omitted. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary, and in practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art should Regions/layers with different shapes, sizes, relative positions can be additionally designed as desired.

1 and 2, the method for calculating the overpressure state of a high temperature reheat steam pipeline in real time according to the present invention includes the following steps:

1) Determine the calculation object

No matter how the high temperature reheat steam pipeline of thermal power plant is arranged and the direction, the calculation object is the high temperature reheat steam pipeline of the unit.

2) Determine the overpressure alarm value

Determine the overpressure alarm value PA of the reheat steam pressure of the high temperature reheat steam pipeline according to the operation regulations.

3) Determine the relevant parameters of the calculation

Calculation-related parameters include overpressure calculation parameters and unit operating state parameters.

Among them, the overpressure calculation parameter is the reheat steam pressure RHP. When there are multiple reheat steam pressure measurement points, the subscript i in the lower right corner is used to distinguish, and each reheat steam pressure RHP _i participates in the real-time calculation.

The operating state parameters of the unit include real-time power generation P _e and installed capacity P _e0 .

4) Start calculation and get real-time data

Calculate from the current time t _now , obtain the reheat steam pressure RHP _i of each reheat steam pressure measurement point, and then go to step 5);

5) Judgment of unit operation

Obtain the real-time power generation P _e (t _now-1 ) of the generated power at the previous time t _now-1 and the real-time power generation P _e (t _now ) at the current time t _now , and judge whether the unit is running and continues to run normally. ;

Wherein, when the condition shown in formula (1) is satisfied, it is considered that the unit is running and continues to operate, then go to step 6), otherwise, it is considered that the unit is shut down or running, then go to step 4);

6) Judgment of overpressure at the measuring point

Obtain the reheat steam pressure RHP _i (t _now-1 ) of each reheat steam pressure measurement point at the previous time t _now-1 and the reheat steam pressure RHP _i (t _now ) at the current time t _now , and proceed accordingly Overpressure judgment.

When the condition shown in formula (2) is satisfied, it is considered that the reheat steam pressure measuring point is not overpressured, then go to step 4);

if RHP _i (t _now-1 )<PA∨RHP _i (t _now )<PA (2)

When the condition shown in formula (3) is satisfied, it is considered that the reheat steam pressure measuring point starts to overpressure, then go to step 4);

if RHP _i (t _now-1 )<PA∨RHP _i (t _now )>=PA (3)

When the condition shown in formula (4) is satisfied, it is considered that the reheat steam pressure measurement point continues to be overpressured, and then continue to step 4);

if RHP _i (t _now-1 )>=PA∨RHP _i (t _now )>=PA (4)

When the condition shown in formula (5) is satisfied, it is considered that the overpressure of the reheat steam pressure measuring point is over, and then go to step 7);

if RHP _i (t _now-1 )>=PA∨RHP _i (t _now )<PA (5)

7) Real-time calculation of single overpressure state value and accumulated overpressure state value of measuring point

When the overpressure of the reheated steam pressure measuring point ends, confirm the single complete overpressure process before the current time t _now (as shown in Figure 2), and obtain the reheating of all the reheated steam pressure measuring points during the single overpressure process steam pressure RHP _i (t), and calculate in real time the single overpressure state value S _i (t) of each reheat steam pressure measurement point before the current time t _now according to formula (6):

Among them, t _start is the overpressure start time of a single overpressure process, and tend is the overpressure _end time of a single overpressure process.

Extend the statistical time, and calculate in real time the accumulated overpressure state value S _i of each reheat steam pressure measurement point up to the current time t _now according to formula (7):

Among them, t ₀ is the initial time of calculation, and t _now is the current time.

8) Calculate the cumulative overpressure state value S of the high temperature reheat steam pipeline up to the current moment in real time, and represent the overpressure status of the high temperature reheat steam pipeline by the cumulative overpressure status value S of the high temperature reheat steam pipeline up to the current moment;

According to the accumulated overpressure state value S _i of each reheat steam pressure measurement point up to the current time t _now , and according to formula (8), the accumulated overpressure state value S of the high-temperature reheat steam pipeline up to the current time is calculated as:

S=max{S ₁ ,S ₂ ,S ₃ ...,S _i ...,S _n } (8)

Among them, i indicates that the high temperature reheat steam pipeline has n reheat steam pressure measuring points.

Finally, the real-time calculation is completed, and the single overpressure state value of the reheat steam pressure measurement point, the accumulated overpressure state value up to the current time, and the accumulated overpressure state value of the high-temperature reheat steam pipeline up to the current time are written into the database. , end this round of calculation, go to 4) to start a new round of calculation.

The above-mentioned embodiment is only one of the embodiments that can realize the technical solution of the present invention. The scope of protection claimed in the present invention is not only limited by this embodiment, but also included in the technical scope disclosed in the present invention. Anyone familiar with the present technology Variations, substitutions, and other implementations will readily occur to those skilled in the art.

Claims (10)

1. a method for calculating high temperature reheat steam pipeline overpressure state in real time, is characterized in that, comprises the following steps: 1) obtain the reheat steam pressure RHP _i of each reheat steam pressure measuring point on the high temperature reheat steam pipeline of the unit; 2) Obtain the real-time generation power P _e (t _now-1 ) of the generation power at the previous time t _now-1 and the real-time generation power P _e (t _now ) at the current time t _now , and use this to judge that the unit is running and continues to run Whether it is normal, when the unit is running and continues to run, go to step 3), otherwise, go to step 1); 3) Determine the reheat steam pressure RHP _i (t _now-1 ) of each reheat steam pressure measuring point on the high temperature reheat steam pipeline of the unit at the previous time t _now-1 and the reheat steam pressure RHP at the current time t _{now i} (t _now ), and judge the overpressure state of the reheat steam pressure measurement point based on this, when the judgment result is no overpressure, starting overpressure or continuous overpressure, then go to step 1), when the judgment result is overpressure When the pressure is over, go to step 4); 4) Confirm the single complete overpressure process before the current time t _now , obtain the reheat steam pressure RHP _i (t) of all reheat steam pressure measurement points in the single complete overpressure process, and use this to calculate the high temperature reheat steam The accumulated overpressure state value S of the pipeline up to the calculation time, and the overpressure state of the high temperature reheat steam pipeline is represented by the accumulated overpressure state value S of the high temperature reheat steam pipeline up to the calculation time. 2. the method for calculating high temperature reheat steam pipeline overpressure state in real time according to claim 1, is characterized in that, the concrete operation of step 4) is: 41) Confirm the single complete overpressure process before the current time t _now , obtain the reheat steam pressure RHP _i (t) of all the reheat steam pressure measuring points in the single overpressure process, and use this to calculate the time before the current time t _now The single overpressure state value S _i (t) of each reheat steam pressure measuring point; 42) According to the single overpressure state value S _i (t) of each reheat steam pressure measurement point before the current time t _now , calculate the cumulative overpressure state value S _i of each reheat steam pressure measurement point up to the current time t _now ; 43) Calculate the accumulated overpressure state value S of the high temperature reheat steam pipeline as of the current time according to the accumulated overpressure state value S _i of each reheat steam pressure measurement point as of the current time _tnow . 3. the method for calculating the overpressure state of high temperature reheat steam pipeline in real time according to claim 2, is characterized in that, when satisfying the condition shown in formula (1), then consider that the unit operates and continues to operate;

4. the method for calculating high temperature reheat steam pipeline overpressure state in real time according to claim 2, is characterized in that, when satisfying the condition shown in formula (2), then think that the reheat steam pressure measuring point is not overpressured; if RHP _i (t _now-1 )<PA∨RHP _i (t _now )<PA (2). 5. the method for calculating high temperature reheat steam pipeline overpressure state in real time according to claim 2, is characterized in that, when satisfying the condition shown in formula (3), then think that the reheat steam pressure measuring point starts overpressure; if RHP _i (t _now-1 )<PA∨RHP _i (t _now )>=PA (3). 6. the method for real-time calculation of high temperature reheat steam pipeline overpressure state according to claim 2, is characterized in that, when satisfying the condition shown in formula (4), then think that reheat steam pressure measuring point continues overpressure; if RHP _i (t _now-1 )>=PA∨RHP _i (t _now )>=PA (4). 7. the method for calculating high temperature reheat steam pipeline overpressure state in real time according to claim 2, is characterized in that, when satisfying the condition shown in formula (5), then think that the overpressure of the reheat steam pressure measuring point ends; if RHP _i (t _now-1 )>=PA∨RHP _i (t _now )<PA (5). 8. the method for calculating high temperature reheat steam pipeline overpressure state in real time according to claim 2, is characterized in that, the single overpressure state value S _i (t of each reheat steam pressure measuring point before current time t _now ):

Among them, t _start is the overpressure start time of a single overpressure process, and tend is the overpressure _end time of a single overpressure process. 9. The method for calculating the overpressure state of high temperature reheat steam pipeline in real time according to claim 2, is characterized in that, the accumulated overpressure state value S _i of each reheat steam pressure measuring point up to the current time t _now :

Among them, t ₀ is the initial time of calculation. 10. the method for calculating the overpressure state of high temperature reheat steam pipeline in real time according to claim 2, is characterized in that, the accumulated overpressure state value S of high temperature reheat steam pipeline up to the current moment is: S=max{S ₁ , S ₂ , S ₃ ..., S _i ..., _Sn } (8).

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