CN113434985B - State evaluation method for tube seat and connecting tube of steam-water separator of supercritical or ultra-supercritical boiler - Google Patents

Abstract

A state evaluation method for a steam-water separator tube seat and a connecting tube of a supercritical or ultra-supercritical boiler comprises the following steps of; 1) Explicitly evaluating the object and the basic information; 2) Defining detailed evaluation points; 3) The specific stage of the full-operation life cycle of the object is clearly evaluated; 4) Calculating a state factor; 5) Calculating a correction factor; 6) Making a metal inspection scheme and implementing the scheme; 7) Obtaining a metal inspection result; 8) Evaluating point states; 9) Evaluating the state of an evaluation object; 10 Filing and feeding back the evaluation result. The invention can help technical boilers or metal professionals in thermal power plants to better formulate maintenance strategies.

Description

Status evaluation of a supercritical or ultra-supercritical boiler steam-water separator pipe seat and connecting pipe estimation method

technical field

The invention belongs to the technical field of state evaluation of thermal power plant equipment, in particular to a method for state evaluation of a supercritical or ultra-supercritical boiler steam-water separator pipe seat and connecting pipe.

Background technique

The steam-water separator of supercritical or ultra-supercritical boiler is an important part of the boiler system of thermal power plants. The steam-water separator is in relatively harsh working conditions during operation, and is easily affected by thermal alternating loads. In particular, there is a large stress concentration phenomenon in the pipe seat and the connecting pipe area of the steam-water separator. The more the pipes are, the more obvious the stress concentration is. Moreover, the welds at the pipe seat are dense. Under the influence of high temperature, high pressure and variable load, the weld seam The deterioration of the organizational state and the fragility of the tissue increase the risk of failure. In addition, because the supercritical or ultra-supercritical boiler steam-water separator pipe seat and connecting pipe are located outside the boiler, if it fails, it will cause serious safety accidents, so it is necessary to evaluate the supercritical or ultra-supercritical boiler steam-water separator pipe seat more accurately and takeover status.

For the steam-water separator of supercritical or ultra-supercritical boilers, the literature has reported the stress analysis and stress distribution of the transient thermo-solid coupling of the tangential miter joint structure at the steam inlet of the steam-water separator based on ANSYS software, such as the literature "Steam-water separation Research on Stress Analysis of Steam Inlet Tangential Miter Joint Structure during Start-Up Stage, Power Station Auxiliary Equipment, 2013 (2)", there are reports based on the finite element method to analyze the thermal stress concentration near the long axis of the elliptical hole of the connecting pipe, such as the literature "600MW Finite element analysis of the internal pressure stress of the supercritical boiler steam-water separator, Boiler Technology, 2009 (1)", there are also reports on the cause of cracks in the fillet weld of the outer wall of the steam-water separator, such as the document "The fillet weld of the outer wall of the medium-pressure steam-water separator Discussion and treatment of seam cracks, Guizhou Chemical Industry, 2012 (2)". There are few reports on the state analysis or life evaluation of the steam-water separator pipe seat and connection pipe. Stress analysis or life assessment of the steam-water separator pipe seat and connecting pipe needs to meet the following conditions: the evaluator needs to have rich basic knowledge of mathematical analysis, basic knowledge of metal materials, mechanical calculation knowledge, life assessment knowledge and experience; needs to collect Complete design information and design data; need to collect complete operating history data; need to collect complete and comprehensive metal inspection related data; need to build stress field and temperature field models; need to conduct comprehensive laboratory analysis data for samples of the same material as a reference group etc. These complicated conditions determine that the development of technologies such as stress analysis and life loss calculation is limited to professional technical institutions and personnel, and the collection of these basic materials and data, complete and comprehensive metal inspection and laboratory analysis will lead to power plant maintenance costs and Increase in labor costs.

To this end, it is necessary to find a universal method that does not require evaluators to have rich basic knowledge of mathematical analysis, basic knowledge of metal materials, mechanical calculation knowledge, life evaluation knowledge and experience, and does not need to bear additional test costs. By obtaining the existing metal inspection data, the status assessment of the supercritical or ultra-supercritical boiler steam-water separator tube seat and connection can be carried out, thus directly helping thermal power plant technicians to formulate maintenance strategies.

Contents of the invention

In order to overcome the above technical problems, the object of the present invention is to provide a method for evaluating the state of the tube base and connecting pipe of the steam-water separator of a supercritical or ultra-supercritical boiler, so as to help technical boiler or metal professionals in thermal power plants to better formulate maintenance strategies.

In order to achieve the above object, the technical scheme adopted in the present invention and the beneficial effects of the present invention are:

A method for evaluating the state of a supercritical or ultra-supercritical boiler steam-water separator pipe seat and connecting pipe, comprising the following steps;

1) Clarify the evaluation object and basic information;

2) Define detailed evaluation points;

3) Clarify the specific stage of the full operation life cycle of the assessment object;

4) Calculate the state factor C _S ;

5) Calculating the correction factor C _C ;

6) Formulate and implement a metal inspection plan;

7) Obtain metal inspection results;

8) Assessment of the status of the assessment point;

9) Evaluation of the status of the evaluation object;

10) Archiving and feedback of evaluation results.

The evaluation object of said step 1) is a supercritical or ultra-supercritical boiler steam-water separator tube seat and a connecting pipe, and the basic information includes design drawings, design diameter, design wall thickness, design material and the last maintenance record file;

Described step 2) specific operation steps are:

Comprehensively consider the maintenance plan, time, cost and previous maintenance results, determine the evaluation points in a targeted manner, and divide the evaluation points into two categories: connecting pipes and pipe sockets, which are distinguished by the subscripts nc and ts respectively.

Described step 3) specific operation steps are:

It is clear which stage the evaluation object is in the early stage, middle stage, final stage and final stage of the full operation life cycle;

Stages of the full operational life cycle Time frames for each phase of the full operational life cycle early stage (0,0.1L _c ] middle stage (0.1L _c ,0.6L _c ] end stage (0.6L _c ,0.85L _c ] terminal stage (0.85L _c ,L _c ]

Among them, L _c is the design life, which is generally defined as the design life of the unit is 30 years.

The specific operation steps of calculating state factor in described step 4) are:

Based on step 3) where the evaluation object is in the full operation life cycle stage, determine its corresponding state factor C _S ;

Stages of the full operational life cycle State Factor C _S early stage 1+s middle stage 1 end stage 1+2s terminal stage 1+5s

According to the design and manufacturing data collected in step 1), look up the value of s according to the table below.

The specific operation steps for calculating the correction factor in the step 5) are:

Based on the feedback of the latest evaluation result of the evaluation object, the correction factor C _C is determined according to formula (1);

In the formula, the values of parameters δ and c can be found from the table below.

Described step 6) specific operation steps are:

Comprehensively considering the maintenance plan, time, cost and previous maintenance results, for the evaluation points determined in step 2), from macroscopic inspection, surface flaw detection, non-destructive flaw detection, metallographic inspection, pipe diameter inspection, wall thickness measurement, hardness inspection, scale thickness Select appropriate items in the measurement to formulate and implement a metal inspection plan.

Described step 7) concrete operation steps are:

According to the metal inspection items determined in step 6), obtain the metal inspection results of the evaluation points, divide the state parameters into three categories according to the metal inspection results, and confirm the state parameters CP and weights corresponding to the metal inspection items of each evaluation point Q.

Described step 8) specific operation steps are:

According to the metal inspection results obtained in step 7), the state of a single evaluation point is evaluated, and the state of a single evaluation point is defined as C _k , and the evaluation model is shown in formula (2);

The numerical result of the state C _k of the evaluation point normally falls within the range of [0,4], and when the value of C _k changes from 0 to 4, the state of the evaluation point becomes worse and worse.

The value of the weight Q _Ii , Q _IIi and Q _IIIi of the three types of state parameters in the formula (2) provides the rule of the formula (3);

Described step 9) in concrete operation steps are:

For all the evaluation points obtained in step 8), statistics are made according to the classification of the nozzles and sockets (the subscripts are nc and ts, respectively), and the number m of evaluation points of the nozzles and the number n of evaluation points of the sockets are counted, and then the evaluation object is evaluated as a whole , the evaluation model of the final state value is shown in formula (12);

If the state C value of the evaluation object is 0, it is considered that the state of the evaluation object is the best. When the C value changes from 0 to 4, the state of the evaluation object gradually becomes worse; when the C value is greater than 2.5, the state of the evaluation object is average, but there are Some assessment points are in poor condition, so technicians should pay attention to them, and timely maintain or replace some assessment points; when the C value is greater than 3.2, the condition of the assessment object is poor, and most of the assessment points are in poor condition. If individual evaluation points are in poor condition, individual evaluation points can be replaced. If the overall status of the assessment object is poor, especially when it is at the end and terminal stage of the full operation life cycle, the enterprise should be prepared for the overall replacement of the assessment object.

The specific operation steps in the step 10) are:

Completely record and file the state evaluation results of the evaluation object obtained in step 9), and provide feedback for the next evaluation to calculate the correction factor in step 5).

The first type of state parameter in the step 8): the macroscopic state parameter CP _I1-k , which is defined by the result R _I1-k of the macroscopic inspection: {no defect found, a small amount of suspicious defect found, and obvious defect found}, such as the formula ( 4) as shown:

The first type of state parameter in the step 8): surface state parameter CP _I2-k , the result R _I2-k of the surface flaw detection inspection: {No defects are found, surface defects are found but eliminated after grinding, surface defects are found but polished } still exists after the definition, as shown in formula (5):

The second type of state parameter in the step 8): the non-destructive state parameter CP _II1-k , which is defined by the result R _II1-k of the non-destructive testing: {level I, level II, level III, level IV}, as shown in formula (6 ) as shown:

The second type of state parameter in the step 8): the tissue state parameter CP _II2-k , which is defined by the metallographic inspection result R _II2-k : {level 1, level 2, level 3, level 4, level 5}, As shown in formula (7):

The third type of state parameter in said step 8): the pipe diameter state parameter CP _III1-k , which is defined by the result R _III1-k of the pipe diameter inspection, as shown in formula (8):

In formula (8), D ₀ is the design pipe diameter, in mm; e is the ultimate creep expansion rate, in %. For the steam-water separator connection, the limit creep expansion rate is shown in the following table:

material alloy steel Carbon steel e value 2.5% 3.5%

The third type of state parameter in said step 8): the wall thickness state parameter CP _III2-k , which is defined by the result R _III2-k of the wall thickness inspection, as shown in formula (9):

In formula (9), d ₀ is the design wall thickness, the unit is mm;

The third type of state parameter in said step 8): the hardness state parameter CP _III3-k , which is defined by the result R _III3-k of the hardness check, as shown in formula (10):

The hardness in formula (10) is the Brinell hardness, HB _L and HB _H are the minimum limit hardness and the maximum limit hardness respectively. For the steam-water separator connection, the values of HB _L and HB _H of common materials are summarized in the following table :

material T22 T23 G102 T91 12C1MoV … HB _L 120 150 150 180 135 … HB _H 163 220 220 250 179 …

The third type of state parameter in said step 8): the oxide scale state parameter CP _III4-k , which is defined by the result R _III4-k of the inner wall oxide scale inspection, as shown in formula (11):

In formula (11), X _H is the maximum permissible oxide skin thickness on the inner wall, in mm. For the connection pipe of the steam-water separator, the X _H values of common materials are summarized in the table below:

material T22 T23 G102 T91 12C1MoV … X _H 0.30 0.30 0.45 0.30 0.35 …

Beneficial effects of the present invention:

The present invention does not require evaluators to have rich basic knowledge of metal materials, mechanical calculation knowledge, life evaluation knowledge and experience, and does not need to bear additional test costs. Inspection, surface flaw detection, non-destructive flaw detection, metallographic inspection, pipe diameter inspection, wall thickness measurement, hardness inspection, scale thickness measurement, these routine metal inspection data, through the correction of state factor and correction factor, supercritical or ultra supercritical The state assessment of the pipe seat and connecting pipe of the steam-water separator of the boiler can directly help the technicians of the thermal power plant to formulate the next maintenance strategy. If the pipe seat and the connecting pipe of the supercritical or ultra-supercritical boiler are in poor condition, they can be replaced separately. If the overall status is poor, the enterprise should prepare for the overall replacement of the evaluation object.

Taking the results of C repair of the left steam-water separator tube seat and connecting pipe of a 660MW supercritical boiler in December 2020 as an example, the state assessment was carried out according to the inventive method. The assessment process and final results are shown below.

Description of drawings

Fig. 1 is a schematic diagram of the status evaluation process of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples of implementation.

As shown in Figure 1:

1) Clarify the evaluation object and basic information

First of all, it is clear that the evaluation object is the supercritical or ultra supercritical boiler steam-water separator nozzle and socket.

In addition, it is also necessary to collect and clarify the design drawings, design diameter, design wall thickness, design material and the latest maintenance record file of the evaluation object.

2) Clear detailed evaluation points

In order to understand the actual state of the evaluation object in detail, it is generally recommended to select multiple locations (connectors and pipe sockets) for inspection on the evaluation object. Since the inspection points will eventually participate in the state evaluation, they are also called evaluation points. And the evaluation points are divided into two categories: connecting pipes and sockets, which are distinguished by the subscripts nc and ts respectively.

3) Clarify the specific stage of the full operation life cycle of the evaluation object

The state of the evaluation object has a certain relationship with the specific stage of the full operation life cycle. In the early stage of the full operation life cycle, the state is not good due to design and manufacturing defects and hidden dangers left over from installation. With the stable operation of the unit and entering the middle stage of the full operation life cycle, the evaluation object has reached the best state and can last for a long time. When entering the final stage of the full operation life cycle, under the influence of the long-term peak-shaving operation of the unit, the state of the evaluation object gradually deteriorates. When entering the final stage of the full operating life cycle, under the long-term service conditions of high temperature and high pressure, the aging of materials is gradually accelerated, and the state of the evaluation object deteriorates rapidly.

It is clear which stage the evaluation object is in the early stage, middle stage, final stage and final stage of the full operation life cycle;

Stages of the full operational life cycle Time frames for each phase of the full operational life cycle early stage (0,0.1L _c ] middle stage (0.1L _c ,0.6L _c ] end stage (0.6L _c ,0.85L _c ] terminal stage (0.85L _c ,L _c ]

Among them, L _c is the design life, which is generally defined as the design life of the unit is 30 years.

4) Calculate the state factor C _S

Based on 3) the stage of the evaluation object, determine its corresponding state factor C _S ;

Stages of the full operational life cycle State Factor C _S early stage 1+s middle stage 1 end stage 1+2s terminal stage 1+5s

According to the design and manufacturing data collected in 1), look up the value of s according to the table below.

If all the indicators in the design and manufacturing data are normal and no major problems are found, then the value of c is 0.01, otherwise, according to the problems found in the design and manufacturing stages, the evaluators can also make adjustments according to the actual conditions of the components.

5) Calculate the correction factor C _C

Based on the feedback of the latest evaluation result of the evaluation object, the correction factor C _C is determined according to formula (1);

In the formula, the values of parameters δ and c can be found from the table below.

6) Formulate and implement a metal inspection plan

Comprehensively considering the maintenance plan, time, cost and previous maintenance results, for the evaluation points determined in step 2), from macroscopic inspection, surface flaw detection, non-destructive flaw detection, metallographic inspection, pipe diameter inspection, wall thickness measurement, hardness inspection, scale thickness Select appropriate items in the measurement to formulate and implement a metal inspection plan.

7) Obtain metal inspection results

According to the metal inspection items determined in step 6), obtain the metal inspection results of the evaluation points, divide the state parameters into three categories according to the metal inspection results, and confirm the state parameters CP and weights corresponding to the metal inspection items of each evaluation point Q.

8) Evaluation point status evaluation

Based on the metal inspection results obtained in 7), the state of a single evaluation point is evaluated, and the state of a single evaluation point is defined as C _k , and the evaluation model is shown in formula (2).

The numerical result of the state C _k of the evaluation point normally falls within the range of [0,4], and when the value of C _k changes from 0 to 4, the state of the evaluation point becomes worse and worse.

Considering the importance of various metal inspection items and their implementation frequency, result accuracy and other factors, for the weights Q _Ii , Q _IIi and Q _IIIi of the three types of state parameters in the above formula (2), the formula (3) the rules;

The evaluation methods of the three types of state parameters of a single evaluation point are given below.

8.1) The first type of state parameter evaluation

8.1.1) Evaluation of macro state parameters corresponding to macro inspection

The result of macro inspection R _I1-k is generally one of the items in the set of {no defect found, defect found, defect found exceeding the standard}, and the definition of the corresponding macro state parameter CP _I1-k is shown in formula (4).

8.1.2) Evaluation of surface state parameters corresponding to surface flaw detection

The result of surface flaw detection R _I2-k is generally {no defect found, surface defect found but eliminated after grinding, surface defect found but still exists after grinding}, and the corresponding surface state parameter CP _I2-k is defined as formula (5 ) shown.

8.2) Evaluation of the second type of state parameters

8.2.1) Evaluation of non-destructive state parameters corresponding to non-destructive testing

Non-destructive testing items can be divided into ultrasonic, magnetic particle, penetrant, and radiographic testing. The results of non-destructive testing R _II1-k are generally defined as {level I, level II, level III, level IV}. If multiple non-destructive testing items are implemented, select The highest rating is the result of non-destructive testing, and the definition of the corresponding non-destructive state parameter CP _II1-k is shown in formula (6).

8.2.2) Evaluation of non-destructive state parameters corresponding to metallographic inspection

The results of metallographic examination R _II2-k are generally defined as {grade 1, grade 2, grade 3, grade 4, grade 5}, and the definition of the corresponding tissue state parameter CP _II2-k is shown in formula (7).

8.3) The third type of state parameter evaluation

8.3.1) Evaluation of wall thickness state parameters corresponding to pipe diameter inspection

When the evaluation object operates under high temperature conditions, the outer diameter creep will gradually occur, and when the creep expansion is severe, it will easily lead to failure.

The definition of the pipe diameter state parameter CP _III1-k corresponding to the pipe diameter inspection result R _III1- k is shown in formula (8).

In formula (8), D ₀ is the design pipe diameter in mm; e is the ultimate creep expansion rate in %. For the steam-water separator connection, the limit creep expansion rate is shown in the table below.

material alloy steel Carbon steel e value 2.5% 3.5%

8.3.2) Evaluation of wall thickness state parameters corresponding to wall thickness inspection

Under the erosion and corrosion of high-temperature steam, the inner wall of the evaluation object will produce high-temperature oxidation, which will gradually consume the base metal of the evaluation object, making the wall thickness thinner, and thus have a worse state.

The wall thickness state parameter CP _III2-k corresponding to the wall thickness inspection result R _III2-k is defined as shown in formula (9).

In formula (9), d ₀ is the design wall thickness in mm.

8.3.3) Evaluation of hardness state parameters corresponding to hardness inspection

The evaluation object will gradually age under high temperature conditions, so the hardness will gradually decrease and the state will deteriorate, which may eventually lead to failure.

The hardness state parameter CP _III3-k corresponding to the hardness test result R _III3- k is defined as shown in formula (10).

The hardness in formula (10) is the Brinell hardness, HB _L and HB _H are the minimum limit hardness and the maximum limit hardness respectively. For the steam-water separator connection, the values of HB _L and HB _H of common materials are summarized in the following table :

material T22 T23 G102 T91 12C1MoV … HB _L 120 150 150 180 135 … HB _H 163 220 220 250 179 …

8.3.4) Evaluation of the scale state parameters corresponding to the scale inspection on the inner wall

Under the erosion and corrosion of high-temperature steam, the inner wall of the evaluation object will undergo high-temperature oxidation, and the formed inner wall oxide layer will increase the heat transfer resistance, which will increase the actual use temperature of the evaluation object and aggravate the aging of the material.

The definition of the scale state parameter CP _III4-k corresponding to the scale inspection result R _III4- k on the inner wall is shown in formula (11).

Equation (11), X _H is the maximum allowable oxide skin thickness on the inner wall, in mm. For the connection pipe of the steam-water separator, the X _H values of common materials are summarized in the table below:

material T22 T23 G102 T91 12C1MoV … X _H 0.30 0.30 0.45 0.30 0.35 …

9) Evaluation of the status of the evaluation object

For all the evaluation points obtained in 8), according to the classification of the nozzles and the sockets (the subscripts are nc and ts), the statistics are made, the number m of the nozzle evaluation points and the number n of the socket evaluation points are counted, and then the evaluation object is evaluated as a whole. The evaluation model of the final state value is shown in formula (12).

If the state C value of the evaluation object is 0, it is considered that the state of the evaluation object is the best. When the C value changes from 0 to 4, the state of the evaluation object gradually becomes worse; when the C value is greater than 2.5, the state of the evaluation object is average, but there are Some assessment points are in poor condition, so technicians should pay attention to them, and timely maintain or replace some assessment points; when the C value is greater than 3.2, the condition of the assessment object is poor, and most of the assessment points are in poor condition. If individual evaluation points are in poor condition, individual evaluation points can be replaced. If the overall status of the assessment object is poor, especially when it is at the end and terminal stage of the full operation life cycle, the enterprise should be prepared for the overall replacement of the assessment object.

10) Archiving and feedback of evaluation results

Completely record and file the state evaluation results of the evaluation object obtained in step 9), and provide feedback for the next evaluation to calculate the correction factor in step 5).

Using the above technical schemes to evaluate the state of the supercritical or ultra-supercritical boiler steam-water separator pipe seat and connecting pipe can not only help thermal power plant technicians understand the actual state of the supercritical or ultra-supercritical boiler steam-water separator pipe seat and connecting pipe, And it can predict the change trend of its state through multiple state evaluation results for the same evaluation point, and can also evaluate the overall state of the supercritical or ultra-supercritical boiler steam-water separator tube seat and connection by integrating the state results of all evaluation points. It is of great significance to formulate maintenance plan and replacement strategy.

Claims (8)

1. A method for evaluating the state of a supercritical or ultra-supercritical boiler steam-water separator socket and a connecting pipe, is characterized in that, comprising the following steps; 1) Clarify the evaluation object and basic information; 2) Define detailed evaluation points; 3) Clarify the specific stage of the full operation life cycle of the assessment object; 4) Calculate the state factor C _S ; 5) Calculating the correction factor C _C ; 6) Formulate and implement a metal inspection plan; 7) Obtain metal inspection results; 8) Assessment of the status of the assessment point; 9) Evaluation of the status of the evaluation object; 10) Archiving and feedback of evaluation results; Described step 5) specific operation steps are: Based on the feedback of the latest evaluation result of the evaluation object, the correction factor C _C is determined according to formula (1);

In the formula, the values of parameters δ and c are found in the table below;

; Described step 8) specific operation steps are: According to the metal inspection results obtained in step 7), the state of a single evaluation point is evaluated, and the state of a single evaluation point is defined as C _k , and the evaluation model is shown in formula (2);

The numerical result of the state C _k of the evaluation point normally falls within the range of [0,4], when the value of C _k changes from 0 to 4, the state of the evaluation point is getting worse; The value of the weight Q _Ii , Q _IIi and Q _IIIi of the three types of state parameters in the formula (2) provides the rule of the formula (3);

The first type of state parameter in the step 8): the macro state parameter CP _I1-k , which is defined by the result R _I1-k of the macro inspection: {no defect found, suspicious defect found, defect found}, such as formula (4) Shown:

The first type of state parameter in said step 8): surface state parameter CP _I2-k , the result R _I2-k of the surface flaw detection inspection: {no defect is found, surface defect is found but eliminated after grinding, surface defect is found but polished } still exists after the definition, as shown in formula (5):

The second type of state parameter in the step 8): the non-destructive state parameter CP _II1-k , which is defined by the result R _II1-k of the non-destructive testing: {level I, level II, level III, level IV}, as shown in formula (6 ) as shown:

The second type of state parameter in the step 8): the tissue state parameter CP _II2-k , which is defined by the metallographic inspection result R _II2-k : {level 1, level 2, level 3, level 4, level 5}, As shown in formula (7):

The third type of state parameter in said step 8): the pipe diameter state parameter CP _III1-k , which is defined by the result R _III1-k of the pipe diameter inspection, as shown in formula (8):

In formula (8), _D0 is the design pipe diameter, the unit is mm; e is the ultimate creep expansion rate, the unit is %; The third type of state parameter in said step 8): the wall thickness state parameter CP _III2-k , which is defined by the result R _III2-k of the wall thickness inspection, as shown in formula (9):

In formula (9), d ₀ is the design wall thickness, the unit is mm; The third type of state parameter in said step 8): the hardness state parameter CP _III3-k , which is defined by the result R _III3-k of the hardness check, as shown in formula (10):

In formula (10), HB _L and HB _H are the minimum limit hardness and the maximum limit hardness respectively; The third type of state parameter in said step 8): the oxide scale state parameter CP _III4-k , which is defined by the result R _III4-k of the inner wall oxide scale inspection, as shown in formula (11):

Equation (11), X _H is the maximum allowable inner wall oxide thickness, in mm. 2. a kind of supercritical or ultra-supercritical boiler steam-water separator socket and the state evaluation method of taking over according to claim 1, it is characterized in that, the evaluation object of described step 1) is supercritical or ultra-supercritical boiler The basic information of steam-water separator pipe seat and connecting pipe includes design drawing, design diameter, design wall thickness, design material and the latest maintenance record file. 3. a kind of supercritical or ultra-supercritical boiler steam-water separator socket and the state evaluation method of taking over according to claim 1, it is characterized in that, described step 2) specific operation steps are: Clarify all the evaluation points of the evaluation object and divide them into: takeover evaluation points and pipe seat evaluation points, which are distinguished by the subscripts nc and ts respectively. 4. a kind of supercritical or ultra-supercritical boiler steam-water separator socket and the state evaluation method of taking over according to claim 1, it is characterized in that, described step 3) specific operation steps are: It is clear which stage the evaluation object is in the early stage, middle stage, final stage and final stage of the full operation life cycle; Stages of the full operational life cycle Time frames for each phase of the full operational life cycle early stage (0,0.1L _c ] middle stage (0.1L _c ,0.6L _c ] end stage (0.6L _c ,0.85L _c ] terminal stage (0.85L _c ,L _c ] Among them, L _c is the design life, which is defined as the design life of the unit is 30 years. 5. a kind of supercritical or ultra-supercritical boiler steam-water separator socket and the state evaluation method of taking over according to claim 1, it is characterized in that, described step 4) in concrete operation steps are: Determine the corresponding state factor C _S based on the stage of the evaluation object clearly defined in step 3); Stages of the full operational life cycle State Factor C _S early stage 1+s middle stage 1 end stage 1+2s terminal stage 1+5s Wherein according to the design and manufacturing information collected in step 1);

. 6. a kind of supercritical or ultra-supercritical boiler steam-water separator socket and the state evaluation method of taking over according to claim 1, it is characterized in that, described step 6) specific operation steps are: Comprehensively considering the maintenance plan, time, cost and previous maintenance results, for the evaluation points determined in step 2), from macroscopic inspection, surface flaw detection, non-destructive flaw detection, metallographic inspection, pipe diameter inspection, wall thickness measurement, hardness inspection, scale thickness Select items in the measurement to develop a metal inspection plan and implement it. 7. a kind of supercritical or ultra-supercritical boiler steam-water separator socket and the state evaluation method of taking over according to claim 1, it is characterized in that, described step 7) concrete operation steps are: According to the metal inspection items determined in step 6), obtain the metal inspection results of the evaluation points, divide the state parameters into three categories according to the metal inspection results, and confirm the state parameters CP and weights corresponding to the metal inspection items of each evaluation point Q;

. 8. a kind of supercritical or ultra-supercritical boiler steam-water separator socket and the state assessment method of taking over according to claim 1, it is characterized in that, described step 9) in concrete operation steps are: For all evaluation points obtained in step 8), statistics are carried out according to the classification of the nozzles and sockets, the number of nozzle evaluation points m and the number of socket evaluation points n are counted, and then the evaluation object is evaluated as a whole. The evaluation model of the final state value is as follows: (12);

If the state C value of the evaluation object is 0, it is considered that the state of the evaluation object is the best. When the C value changes from 0 to 4, the state of the evaluation object gradually deteriorates; Carry out timely maintenance or replacement of some evaluation points; when the C value is greater than 3.2, the enterprise is ready for the overall replacement of the evaluation object; The specific operation steps in the step 10) are: Completely record and file the state evaluation results of the evaluation object obtained in step 9), and provide feedback for the next evaluation to calculate the correction factor in step 5).

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