CN115712984A - Method for evaluating residual life of boiler heating surface tube - Google Patents
Method for evaluating residual life of boiler heating surface tube Download PDFInfo
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- CN115712984A CN115712984A CN202211294301.0A CN202211294301A CN115712984A CN 115712984 A CN115712984 A CN 115712984A CN 202211294301 A CN202211294301 A CN 202211294301A CN 115712984 A CN115712984 A CN 115712984A
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Abstract
The invention discloses a method for evaluating the residual life of a heated surface pipe of a boiler, which comprises the following steps: 1) Determining information of the evaluated pipe section, at least including the accumulated service time t of the evaluated pipe section op (ii) a 2) Determining the equivalent calculated temperature of the pipe wall of the evaluated pipe section; 3) Determining the pipe wall calculated pressure of the evaluated pipe section; 4) Determining a Larson-Miller parameter equation reflecting the permanent strength performance of the material of the evaluated pipe section; 5) Calculating the corrosion thinning rate of the wall thickness of the evaluated pipe section; 6) Calculating the use of fresh pipe at the rate of wall thickness reduction for the evaluated pipe section at corrosion thinning and long term creep to the primary failure modeLife t n (ii) a 7) The remaining life of the pipe section to be evaluated is the service life t of the new pipe obtained in step 6) n Subtracting the accumulated service time t of the evaluation pipe section in the step 1) op . The service life evaluation method of the high-temperature heated surface pipe of the boiler has important significance for the accurate evaluation of the service life of the high-temperature pressure-bearing member of the boiler.
Description
Technical Field
The invention relates to the technical field of residual life assessment of nuclear power parts, in particular to a service life assessment method of a boiler high-temperature heating surface pipe based on interaction of corrosion thinning and creep damage.
Background
The service life evaluation of the heating surface of the boiler is established on the basis of the failure mode, and the main reasons for damage of the superheater and the reheater tube comprise short-time overheating, long-term creep, corrosion to the fire surface, erosion, dissimilar steel welding failure and the like; the damage of the water wall is mainly caused by the corrosion of the working medium side and the high-temperature corrosion of the fire side, if the temperature of the pipe wall does not exceed the metal creep temperature, the residual life is calculated by the pipe wall thinning rate, and if the high-temperature corrosion is caused, the same analysis method as that of the superheater pipe and the reheater pipe is adopted; the main reasons for damage of the economizer are pitting corrosion, abrasion and low-temperature corrosion, and the service life of the corrosion type service life is calculated based on a strength checking theory and the pipe wall thinning rate. The evaluation of the residual life of the heating surface of the boiler mainly aims at taking corrosion thinning, long-term creep deformation, high-temperature corrosion thinning and dissimilar steel welding failure as main failure modes; at present, no method for accurately evaluating the corrosion thinning life of the high-temperature heating surface exists.
Disclosure of Invention
In view of the above, in order to overcome the defects of the prior art, the present invention aims to provide a service life evaluation method for a high temperature heating surface pipe of a boiler based on interaction of corrosion thinning and creep damage.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for evaluating the residual life of a boiler heating surface tube comprises the following steps:
1) Determining background information of the evaluated pipe section, wherein the background information at least comprises the accumulated service time t of the evaluated pipe section op Information;
2) Determining the equivalent calculated temperature of the pipe wall of the evaluated pipe section;
3) Determining the pipe wall calculated pressure of the evaluated pipe section;
4) Determining a Larson-Miller parameter equation reflecting the permanent strength performance of the material of the evaluated pipe section;
5) Calculating the corrosion thinning rate of the wall thickness of the evaluated pipe section;
6) The service life t of a new pipe section to be evaluated at this rate of wall thickness reduction is calculated for the main failure mode of corrosion thinning and creep over time n ；
7) The remaining life of the pipe section to be evaluated is the service life t of the new pipe obtained in step 6) n Subtracting the accumulated service time t of the evaluated pipe section in the step 1) op 。
According to some preferred embodiments of the invention, the information of the estimated pipe section comprises the material and the outer diameter D of the estimated pipe section o Initial wall thickness delta 0 Current wall thickness delta 1 。
According to some preferred aspects of the invention, the initial wall thickness δ 0 And current wall thickness delta 1 Only on the wall of the tubeThickness of the metal substrate layer.
According to some preferred aspects of the invention, the equivalent service temperature T c Design temperature T from tube wall d Design of wall thickness of tube wall and calculated temperature T s And wall equivalent temperature T d And the aging state of the pipe wall material are determined together.
According to some preferred embodiments of the invention, the calculated pressure P of the pipe wall is the normal operating pressure P of the pipe wall op 。
According to some preferred aspects of the invention, the Larson-Miller parametric equation is as shown in equations (1) and (2):
P(σ)＝(T+273.15)(C+lg t r ) (1)
P(σ)＝C 0 +C 1 lgσ+C 2 lg 2 σ+C 3 lg 3 σ+C 4 lg 4 σ (2)
in the formula: t is the temperature in centigrade, DEG C; t is t r Creep rupture time, h; sigma is initial creep loading stress, MPa; c is the Larson-Miller constant, C 0 、C 1 、C 2 、C 3 、C 4 Is a material constant.
According to some preferred aspects of the invention, the parameter determination of the material L-M can be solved for the corresponding material constant value by multiple linear regression using equation (3):
lgt r ＝(C 1 lgσ+C 2 lg 2 σ+C 3 lg 3 σ+C 4 lg 4 σ+C 0 )/(T+273.15)-C (3)。
according to some preferred aspects of the invention, the estimated pipe segment wall thickness corrosion reduction rate v is given by the formula
And (4) calculating.
According to some preferred embodiments of the invention, the cumulative life loss D of the heated face tube is determined by the corrosion thinning and long creep as the dominant failure modes tc Is calculated by the formula (4):
in the formula: c is the Larson-Miller constant, C 0 、C 1 、C 2 、C 3 、C 4 Is a material constant; k is a radical of 1 For the stress coefficient, 1.5 is taken for the heated surface component; k is a radical of 2 For the safety coefficient of the thickness reduction of the wall thickness corrosion, 1.1 is taken for the heating surface part; m is a material service environment parameter, n is a material service environment parameter, P is a pipe wall calculated pressure, and x is an integral independent variable.
According to some preferred aspects of the invention, the wall thickness corrosion reduction size safety factor is 1.0 for components with general failure consequences and 1.1 for components with severe failure consequences.
According to some preferred embodiments of the invention, m is calculated by equation (5):
in the formula: a is the service environment parameter of the material, and B is the service environment parameter of the material.
According to some preferred embodiments of the invention, n is calculated by equation (6):
in the formula: a is the service environment parameter of the material, B is the service environment parameter of the material, C i The LMP (. Sigma.) material constants in the Larson-Miller fit curves were obtained.
According to some preferred embodiments of the invention, a is calculated by equation (7):
A＝T c +273.15 (7)
in the formula: t is c Is the equivalent service temperature.
According to some preferred embodiments of the invention, B is calculated by equation (8):
B＝(T c +273.15)·C (8)
in the formula: t is a unit of c C is the Larson-Miller constant for equivalent service temperature.
Due to the adoption of the technical scheme, compared with the prior art, the invention has the beneficial effects that: the service life evaluation method for the high-temperature heated surface pipe of the boiler is suitable for evaluating the residual service life of the heated surface of the boiler in a main failure mode of corrosion reduction and high-temperature creep, can also be used for evaluating the service life of other high-temperature pressure-bearing pipelines in the fields of thermal power, petroleum and petrochemical industry and the like by taking long-time creep and corrosion reduction as main failure modes, and has important significance for accurately evaluating the service life of the high-temperature pressure-bearing component of the boiler.
Detailed Description
In order to make those skilled in the art better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The service life evaluation method of the boiler high-temperature heating surface pipe based on the interaction of corrosion thinning and creep damage in the embodiment specifically comprises the following steps:
step 1) determining information of the pipe section to be evaluated
The information of the evaluated pipe section comprises the material of the evaluated pipe section (determined according to LMP function determined by the material), and the accumulated service time t op Outer diameter D o Initial wall thickness delta 0 Current wall thickness delta 1 . Wherein the initial wall thickness delta 0 From the current wall thickness delta 1 It should be only the thickness of the metal substrate layer of the tube wall.
Step 2) determining the equivalent calculated temperature T of the pipe wall of the evaluated pipe section c 。
Equivalent service temperature T c Design of pipe taking wallTemperature T d Wall thickness design calculation temperature T s And wall equivalent temperature T d Is measured.
And 3) determining the pipe wall calculation pressure P of the evaluated pipe section.
The normal working pressure P of the pipe wall is obtained from the calculated pressure P of the pipe wall op 。
Step 4) determining a Larson-Miller parameter equation reflecting the permanent strength performance of the material of the pipe section to be evaluated
The Larson-Miller parameter equation is in the form of equations (1) and (2), wherein the parameter determination for the materials L-M can be solved by multiple linear regression using equation (3) to obtain the corresponding values for the material constants.
P(σ)＝(T+273.15)(C+lg t r ) (1)
P(σ)＝C 0 +C 1 lgσ+C 2 lg 2 σ+C 3 lg 3 σ+C 4 lg 4 σ (2)
lgt r ＝(C 1 lgσ+C 2 lg 2 σ+C 3 lg 3 σ+C 4 lg 4 σ+C 0 )/(T+273.15)-C (3)
In the formula: t is the temperature in centigrade, DEG C; t is t r Creep rupture time, h; sigma is initial creep loading stress, MPa; c is the Larson-Miller constant, C 0 、C 1 、C 2 、C 3 、C 4 Is a material constant.
Step 5), calculating the corrosion thinning rate v of the wall thickness of the evaluated pipe section,
step 6), calculating the service life t of the new pipe of the evaluated pipe section at the wall thickness reduction rate by taking corrosion reduction and long-term creep (high-temperature creep) as main failure modes n 。
Specifically, when the hot face tube is subjected to corrosion thinning and long creep as the primary failure mode, its cumulative life loss D increases with time in service tc Can be calculated by equation (4).
In the formula: c is the Larson-Miller constant, C 0 、C 1 、C 2 、C 3 、C 4 Is the material constant; k is a radical of 1 Taking 1.5 for the heated surface tube as a stress coefficient; k is a radical of 2 For the safety factor of the size of the wall thickness corrosion thinning quantity, 1.0 is taken for the part with the general failure consequence, and 1.1 is taken for the part with the serious failure consequence; m is a material service environment parameter and is obtained by calculation according to a formula (5); n is a material service environment parameter and is obtained by calculation according to a formula (6); p is the calculated wall pressure and x is the integral argument.
In the formula: a is a material service environment parameter and is obtained by calculation according to a formula (7); b is a material service environment parameter which is obtained by calculation according to a formula (8); c i Is the material parameter in the LM function.
A＝T c +273.15 (7)
B＝(T c +273.15)·C (8)
When the life loss D is accumulated tc =1, the corresponding time t is the service life t of the new pipe of the evaluated pipe section n . The solution of equation (4) can be solved by numerical solution, incremental cycles are carried out on time x by adopting dx as increment step by step, and D corresponding to each cycle process is calculated tc When D is present tc When the time t is more than or equal to 1, the circulation is withdrawn and the corresponding previous step time t is output, and the time t at the moment is the service life t of the new pipe of the evaluated pipe section n 。
Step 7) calculating the residual life t of the evaluated pipe section left ＝t n -t op 。
The residual life evaluation of the heating surface is mainly aimed at taking corrosion thinning, long-term creep, high-temperature corrosion thinning and dissimilar steel welding failure as main failure modes. Aiming at the problem that an accurate evaluation method for the corrosion thinning life of the high-temperature heating surface is not available at present, the method for evaluating the service life of the high-temperature heating surface pipe of the boiler based on the interaction of corrosion thinning and creep damage is suitable for evaluating the residual life of the heating surface of the boiler in a main failure mode of corrosion thinning and high-temperature creep, can also be used for evaluating the life of other high-temperature pressure-bearing pipelines in the fields of thermal power, petroleum and petrochemical industry and the like in a main failure mode of long-term creep and corrosion thinning, and has important significance for accurately evaluating the service life of a high-temperature pressure-bearing component of the boiler.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (15)
1. A method for evaluating the residual life of a heating surface tube of a boiler is characterized by comprising the following steps:
1) Determining information of the evaluated pipe section, at least including the accumulated service time t of the evaluated pipe section op Information;
2) Determining the equivalent calculated temperature of the pipe wall of the evaluated pipe section;
3) Determining the pipe wall calculated pressure of the evaluated pipe section;
4) Determining a Larson-Miller parameter equation reflecting the permanent strength performance of the material of the evaluated pipe section;
5) Calculating the corrosion thinning rate of the wall thickness of the evaluated pipe section;
6) Calculating the service life t of the new pipe section to be evaluated at the rate of wall thickness reduction at the time of corrosion thinning and long-term creep into the primary failure mode n ；
7) The remaining life of the pipe section to be evaluated is the service life t of the new pipe obtained in step 6) n Subtracting the cumulative garment of the section to be evaluated in step 1)Time of service t op 。
2. The assessment method according to claim 1, wherein said information of the assessed pipe section comprises the material and outer diameter D of the assessed pipe section o Initial wall thickness delta 0 Current wall thickness δ 1 。
3. The evaluation method according to claim 2, wherein the initial wall thickness δ 0 And current wall thickness delta 1 The thickness of the metal substrate layer on the pipe wall is only.
4. The evaluation method according to claim 1, wherein the equivalent service temperature T c Design temperature T from tube wall d Wall thickness design calculation temperature T s And wall equivalent temperature T d And the aging state of the pipe wall material are determined together.
5. The evaluation method according to claim 1, wherein the pipe wall calculated pressure P is a normal working pressure P of the pipe wall op 。
6. The evaluation method according to claim 1, wherein the Larson-Miller parameter equation is as shown in formula (1) and formula (2):
P(σ)＝(T+273.15)(C+lgt r ) (1)
P(σ)＝C 0 +C 1 lgσ+C 2 lg 2 σ+C 3 lg 3 σ+C 4 lg 4 σ (2)
in the formula: t is the temperature in centigrade, DEG C; t is t r Creep rupture time, h; sigma is initial creep loading stress, MPa; c is the Larson-Miller constant, C 0 、C 1 、C 2 、C 3 、C 4 Is a material constant.
7. The evaluation method according to claim 6, wherein the parameter determination of the material L-M can be solved by multiple linear regression using equation (3) to obtain the corresponding material constant value:
lgt r ＝(C 1 lgσ+C 2 lg 2 σ+C 3 lg 3 σ+C 4 lg 4 σ+C 0 )/(T+273.15)-C (3)。
8. the method of claim 1, wherein the rate of corrosion reduction of wall thickness v of the pipe section being evaluated is determined by the formula
And (4) calculating.
9. The method of claim 1, wherein the cumulative life loss D is calculated as the major failure mode for the heated face tube due to corrosion thinning and long creep tc Is calculated by the formula (4):
in the formula: c is the Larson-Miller constant, C 0 、C 1 、C 2 、C 3 、C 4 Is a material constant; k is a radical of 1 For the stress coefficient, 1.5 is taken for the heated surface component; k is a radical of 2 For the safety coefficient of wall thickness corrosion reduction size, 1.1 is taken for the heating surface part; m and n are material constants, P is calculated pressure of the pipe wall, and x is an integral independent variable.
10. The evaluation method according to claim 9, wherein the wall thickness corrosion reduction is a dimensional safety factor of 1.0 for components with general failure consequences and 1.1 for components with severe failure consequences.
11. The evaluation method according to claim 9, wherein m is calculated by formula (5):
in the formula: A. and B are all material service environment parameters.
12. The evaluation method according to claim 9, wherein n is calculated by formula (6):
in the formula: A. b are parameters of the service environment of the material, C i LMP (. Sigma.) material constants in Larson-Miller fitted curves.
13. The evaluation method according to claim 11 or 12, wherein a is calculated by formula (7):
A＝T c +273.15 (7)
in the formula: t is c Is the equivalent service temperature.
14. The evaluation method according to claim 11 or 12, wherein B is calculated by formula (8):
B＝(T c +273.15)·C (8)
in the formula: t is c C is the Larson-Miller constant for equivalent service temperature.
15. The evaluation method according to claim 9, wherein the formula (9) is calculated by:
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| CN117648817A (en) * | 2023-12-05 | 2024-03-05 | 北京化工大学 | Process pipeline corrosion data acquisition method, electronic equipment and storage medium |
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| CN117648817A (en) * | 2023-12-05 | 2024-03-05 | 北京化工大学 | Process pipeline corrosion data acquisition method, electronic equipment and storage medium |
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