Method for designing and monitoring low-cycle fatigue crack propagation life of fuel control valve

Abstract

The invention provides a method for designing and monitoring the low-cycle fatigue crack propagation life of a fuel control valve, and the method achieves the design and monitoring of the low-cycle fatigue crack propagation life of a natural gas and hydrogen fuel control valve through the steps of analysis model construction, data collection, analysis calculation and life monitoring and optimization and improvement. And safe service of the fuel control valve is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of gas turbines, and in particular to a method for designing and monitoring the low-cycle fatigue crack growth life of a fuel control valve. Background Art

[0002] The fuel control valve is the core equipment of the fuel system of heavy-duty gas turbines and hydrogen-fueled gas turbines. Since gas turbines generally operate as peak-shaving units, they need to be started and stopped frequently, and the parameters of natural gas or hydrogen change dramatically. The stress caused by thermal load and the stress caused by gas pressure load will cause low-cycle fatigue expansion of cracks (or defects) on the external surface of important components of the fuel control valve, affecting the safe service of the fuel control valve.

[0003] In the field of engineering design, since the valve housing of the gas turbine fuel control valve is a durable part, its shape is usually irregular during design and the stress level is high, making it a component where low-cycle fatigue cracks are very likely to initiate and propagate.

[0004] However, there is no suitable life design and monitoring method and system available for the design and production of fuel control valves in the field of heavy-duty gas turbines and hydrogen-fueled gas turbines in China. Therefore, it is of great significance to develop a method for designing and monitoring the life of low-cycle fatigue crack growth of fuel control valves. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for designing and monitoring the low-cycle fatigue crack growth life of a fuel control valve. Through modeling, data collection, analysis and calculation, life monitoring and optimization improvement steps, the design and monitoring of the low-cycle fatigue crack growth life of natural gas and hydrogen fuel control valves are realized to ensure the safe service of the fuel control valve.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for designing and monitoring the low cycle fatigue crack growth life of a fuel control valve, the method being applicable to natural gas and hydrogen fuel control valves, the method comprising the following steps:

[0008] (1) Construct a finite element stress analysis model of the fuel control valve;

[0009] (2) Determine the material grade and performance parameters of each component of the fuel control valve;

[0010] (3) Calculation of the maximum stress σ for low-cycle fatigue crack growth in the fuel control valve max ;

[0011] (4) Calculation of the critical crack size a for low-cycle fatigue crack growth in the fuel control valve c ;

[0012] (5) Calculation of the low cycle fatigue crack growth life N of the fuel control valve f ;

[0013] (6) Calculation of the fuel control valve low cycle fatigue crack growth calendar life τ f ;

[0014] (7) Determine the fuel control valve low cycle fatigue crack growth calendar life criterion value τ0;

[0015] (8) Carry out design monitoring and optimization of the low-cycle fatigue crack growth life of fuel control valves.

[0016] The method for designing and monitoring the low-cycle fatigue crack growth life of a fuel control valve described in the present invention first constructs a finite element stress analysis model of the fuel control valve and determines the material grades and performance parameters of each component of the fuel control valve. Then, the maximum stress σ of the low-cycle fatigue crack growth of the fuel control valve is calculated. max , the critical crack size a for low cycle fatigue crack growth c , low cycle fatigue crack growth life N f and low cycle fatigue crack growth calendar life τ f ; After determining the criterion value τ0 of the low-cycle fatigue crack growth calendar life of the fuel control valve, the design monitoring and optimization of the low-cycle fatigue crack growth life of the fuel control valve are carried out. When the low-cycle fatigue crack growth life monitoring of the fuel control valve fails, the stress level of the crack occurrence site is reduced by optimizing and improving the relevant structure of the fuel control valve so that the low-cycle fatigue crack growth life of the fuel control valve meets the requirements. The method of the present invention realizes the design monitoring and optimization improvement of the low-cycle fatigue crack growth life of the fuel control valve in the design stage to ensure the safe service of the fuel control valve of the gas turbine.

[0017] The method for designing and monitoring the low-cycle fatigue crack growth life of a fuel control valve of the present invention can also be used for designing and monitoring the low-cycle fatigue crack growth life of fuel control valve parts.

[0018] In the present invention, the construction of the finite element stress analysis model of the fuel control valve described in step (1) is not limited in detail. Those skilled in the art can use existing modeling software and existing technologies in the field to construct the finite element stress analysis model of the fuel control valve based on design drawings.

[0019] Preferably, the performance parameters in step (2) include physical performance parameters and fracture mechanics performance parameters;

[0020] Preferably, the physical property parameters include density ρ, elastic modulus E, Poisson's ratio υ, linear expansion coefficient α, specific heat capacity Cp and thermal conductivity λ;

[0021] Preferably, the fracture mechanics performance parameters include fracture toughness K IC , fatigue crack growth threshold ΔK th , material constants C0 and m0 of crack fatigue growth.

[0022] Preferably, the maximum stress σ in step (3) max The calculation formula is:

[0023] σ max =σ1+σ re (1)

[0024] In the formula, σ re - residual stress of fuel control valve;

[0025] σ1——The maximum principal stress of the crack part of the fuel control valve under each transient working condition;

[0026] Preferably, the transient operating conditions include hot start, warm start and cold start of the gas turbine.

[0027] Preferably, tensile stress is the main factor causing fatigue crack growth, and compressive stress has little effect on fatigue crack growth. Since the stress level during shutdown is 0, the fatigue crack growth of the fuel control valve can also be regarded as a low-cycle pulsating fatigue stress cycle. The cyclic stress range Δσ max That is, the maximum stress σ max .

[0028] Preferably, the critical crack size a in step (4) is c The calculation formula is:

[0029]

[0030] Where, M is a constant related to crack shape parameters.

[0031] Preferably, the low cycle fatigue crack growth life N of the fuel control valve in step (5) is f The calculation formula is:

[0032]

[0033] Where:

[0034] a i — initial size of the crack;

[0035] n f ——Safety factor of low cycle fatigue crack growth life;

[0036] Preferably, during the design phase, a i Take 2mm.

[0037] Preferably, the low cycle fatigue crack growth calendar life τ under each transient condition is f The calculation formula is:

[0038]

[0039] Where:

[0040] y c ——Annual average number of cold starts;

[0041] y w ——Annual average number of warm-state starts;

[0042] y h ——Annual average number of hot starts;

[0043] N fc - fatigue crack growth life during cold start-up;

[0044] N fw - fatigue crack growth life during warm starting;

[0045] N fh ——Fatigue crack growth life during hot start-up.

[0046] Preferably, the criterion value τ0 of the low cycle fatigue crack growth calendar life of the fuel control valve is determined according to the design requirements of the gas turbine power station and the fuel control valve;

[0047] Preferably, for gas turbine power plants, the design requirement for natural gas and hydrogen fuel control valves is τ0 = 30 years.

[0048] Preferably, the step of carrying out design monitoring and optimization of the low cycle fatigue crack growth life of the fuel control valve in step (8) specifically includes:

[0049] If τ f ≥τ0, the low-cycle fatigue crack growth calendar life design monitoring of the fuel control valve is qualified, the low-cycle fatigue crack growth life of the fuel control valve is under control, and the low-cycle fatigue crack growth life monitoring of the fuel control valve is completed;

[0050] If τ f <τ0, the fuel control valve's low-cycle fatigue crack growth calendar life design monitoring fails. The fuel control valve structure is optimized and improved during the design phase, and the structural fillet radius of the relevant parts is increased to reduce the stress level of the cracked parts. Steps (1) to (8) are re-executed until τ f ≥τ0.

[0051] As a preferred technical solution of the present invention, the method is applicable to natural gas and hydrogen fuel control valves, and the method comprises the following steps:

[0052] (1) Using existing modeling software, a finite element stress analysis model of the fuel control valve is constructed based on the design drawings;

[0053] (2) Determine the material grade and performance parameters of each component of the fuel control valve; the performance parameters include physical performance parameters and fracture mechanics performance parameters; the physical performance parameters include density ρ, elastic modulus E, Poisson's ratio υ, linear expansion coefficient α, specific heat capacity Cp and thermal conductivity λ; the fracture mechanics performance parameters include fracture toughness K IC , fatigue crack growth threshold ΔK th , material constants C0 and m0 for crack fatigue growth;

[0054] (3) Calculation of the maximum stress σ for low-cycle fatigue crack growth in the fuel control valve max , the calculation formula is:

[0055] σ max =σ1+σ re (1)

[0056] In the formula, σ re - residual stress of fuel control valve;

[0057] σ1——The maximum principal stress of the crack part of the fuel control valve under each transient working condition;

[0058] The transient operating conditions include hot start, warm start and cold start of the gas turbine;

[0059] (4) Calculation of the critical crack size a for low-cycle fatigue crack growth in the fuel control valve c , the calculation formula is:

[0060]

[0061] Where, M is a constant related to crack shape parameters;

[0062] (5) Calculation of the low cycle fatigue crack growth life N of the fuel control valve f , the calculation formula is:

[0063]

[0064] Where:

[0065] a i ——The initial size of the crack; in the design stage, a i Take 2mm;

[0066] n f ——Safety factor of low cycle fatigue crack growth life;

[0067] (6) Calculation of the fuel control valve low cycle fatigue crack growth calendar life τ f , the formula is:

[0068]

[0069] Where:

[0070] y c ——Annual average number of cold starts;

[0071] y w ——Annual average number of warm-state starts;

[0072] y h ——Annual average number of hot starts;

[0073] N fc - fatigue crack growth life during cold start-up;

[0074] N fw - fatigue crack growth life during warm starting;

[0075] N fh - fatigue crack growth life during hot start-up;

[0076] (7) Determine the low-cycle fatigue crack growth calendar life criterion value τ0 of the fuel control valve; for gas turbine power plants, the design requirement for natural gas and hydrogen fuel control valves is τ0 = 30 years;

[0077] (8) Carry out design monitoring and optimization of low cycle fatigue crack growth life of fuel control valves;

[0078] If τ f ≥τ0, the low-cycle fatigue crack growth calendar life design monitoring of the fuel control valve is qualified, the low-cycle fatigue crack growth life of the fuel control valve is under control, and the low-cycle fatigue crack growth life monitoring of the fuel control valve is completed;

[0079] If τ f <τ0, the fuel control valve's low-cycle fatigue crack growth calendar life design monitoring fails. The fuel control valve structure is optimized and improved during the design phase, and the structural fillet radius of the relevant parts is increased to reduce the stress level of the cracked parts. Steps (1) to (8) are re-executed until τ f ≥τ0.

[0080] In a second aspect, the present invention further provides a device system for designing and monitoring the low cycle fatigue crack growth life of a fuel control valve, wherein the device system performs the method for designing and monitoring the low cycle fatigue crack growth life of a fuel control valve described in the first aspect.

[0081] Preferably, the device system comprises a modeling module and a data collection module which are independent of each other;

[0082] Preferably, the modeling module and the data collection module are respectively connected to the analysis and calculation module, the life monitoring module and the optimization and improvement module in sequence.

[0083] The device system for designing and monitoring the low-cycle fatigue crack growth life of a fuel control valve described in the present invention is reasonably designed. When the data output by the life monitoring module is qualified, the data is output, and the design and monitoring of the low-cycle fatigue crack growth life of the fuel control valve is completed; when the data output by the life monitoring module is unqualified, the data is input into the optimization and improvement module for optimization processing, and continues to be input into the modeling module and the data collection module respectively, starting a new round of low-cycle fatigue crack growth life design and monitoring, until the data output by the life monitoring module is qualified.

[0084] Compared with the prior art, the present invention has at least the following beneficial effects:

[0085] (1) The method for designing and monitoring the low-cycle fatigue crack growth life of a fuel control valve provided by the present invention realizes the design monitoring and optimization improvement of the low-cycle fatigue crack growth life of a fuel control valve. When the monitoring of the low-cycle fatigue crack growth life of a fuel control valve fails, the structural fillet radius of the relevant components of the fuel control valve can be increased so that the low-cycle fatigue crack growth life of the fuel control valve meets the requirements.

[0086] (2) The method for designing and monitoring the low-cycle fatigue crack growth life of a fuel control valve provided by the present invention can also be used for designing and monitoring the low-cycle fatigue crack growth life of fuel control valve components. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 is a flow chart of a method for designing and monitoring low cycle fatigue crack growth life of a fuel control valve in a specific embodiment of the present invention;

[0088] Figure 2 It is a block diagram of a device system for designing and monitoring the low-cycle fatigue crack growth life of a fuel control valve in a specific embodiment of the present invention;

[0089] Figure 3 It is a schematic diagram of the structure of a natural gas and hydrogen fuel control valve for a certain type of heavy-duty gas turbine in a specific implementation manner of the present invention. DETAILED DESCRIPTION

[0090] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0091] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0092] As a specific embodiment of the present invention, a method for designing and monitoring the low cycle fatigue crack growth life of a fuel control valve is provided, and its flow chart is as follows: Figure 1 shown.

[0093] The block diagram of the device system for designing and monitoring the low cycle fatigue crack growth life of the fuel control valve used in the method is as follows Figure 2 shown.

[0094] The device system comprises a modeling module and a data collection module which are independent of each other; the modeling module and the data collection module are respectively connected with the analysis and calculation module, the life monitoring module and the optimization and improvement module in sequence.

[0095] This specific implementation method takes a certain type of heavy-duty gas turbine natural gas and hydrogen fuel control valve with a nominal diameter of DN80 as an example to carry out low-cycle fatigue crack growth life design and monitoring. The structural schematic diagram of the heavy-duty gas turbine natural gas and hydrogen fuel control valve is shown in FIG. Figure 3 shown.

[0096] According to structural strength analysis and engineering experience, the stress level at part A of the valve shell of natural gas and hydrogen fuel control valves under transient operating conditions is the highest. It is a weak part and is very prone to crack propagation, so low-cycle fatigue crack design and monitoring are required for this part.

[0097] The method for designing and monitoring the low cycle fatigue crack growth life of a fuel control valve comprises the following steps:

[0098] (1) Using existing 3D modeling software, construct finite element stress analysis models of natural gas and hydrogen fuel control valves based on design drawings;

[0099] (2) Determine the material grade of each component of the natural gas and hydrogen fuel control valve as CF8M and performance parameters; the performance parameters include physical performance parameters and fracture mechanics performance parameters; the physical performance parameters include density ρ = 7810 kg / m 3 , elastic modulus E = 183 GPa, Poisson's ratio υ = 0.3, linear expansion coefficient α = 1.7 × 10 -5 / ℃, specific heat capacity Cp=514J / (kg·℃) and thermal conductivity λ=16.8W / (m·℃); the fracture mechanics performance parameters include fracture toughness Fatigue crack growth threshold The material constant of crack fatigue growth is C0 = 2.8 × 10 -13 , m0=4.0686;

[0100] (3) Calculation of the maximum stress σ for low-cycle fatigue crack growth in natural gas and hydrogen fuel control valves max , the calculation formula is:

[0101] σ max =σ1+σ re (1)

[0102] In the formula, σ re ——Residual stress of natural gas and hydrogen fuel control valves is 5% of the yield limit of the fuel control valve material at operating temperature;

[0103] σ1——The maximum principal stress of the crack position of natural gas and hydrogen fuel control valves under various transient conditions;

[0104] The transient operating conditions include hot start, warm start and cold start of the gas turbine;

[0105] (4) Calculation of the critical crack size a for low cycle fatigue crack growth in natural gas and hydrogen fuel control valves c , the calculation formula is:

[0106]

[0107] In the formula, fracture toughness K IC for

[0108] M——constant related to crack shape parameters, taken as 4.318;

[0109] (5) Calculation of low cycle fatigue crack growth life N of natural gas and hydrogen fuel control valves f , the calculation formula is:

[0110]

[0111] Where:

[0112] a i ——The initial size of the crack is 2 mm;

[0113] n f ——Low cycle fatigue crack growth life safety factor, take 2;

[0114] The maximum stress σ under each transient condition corresponding to the outer surface A of the natural gas and hydrogen fuel control valve of this type of heavy-duty gas turbine max , critical crack size a c , low cycle fatigue crack growth life N f The calculation results are listed in Table 1:

[0115] Table 1

[0116]

[0117] (6) Calculation of low cycle fatigue crack growth calendar life τ for natural gas and hydrogen fuel control valves f , the formula is:

[0118]

[0119] Where:

[0120] y c ——Annual average number of cold starts;

[0121] y w ——Annual average number of warm-state starts;

[0122] y h ——Annual average number of hot starts;

[0123] N fc - fatigue crack growth life during cold start-up;

[0124] N fw - fatigue crack growth life during warm starting;

[0125] N fh - fatigue crack growth life during hot start-up;

[0126] (7) For gas turbine power plants, the design requirement for natural gas and hydrogen fuel control valves is τ0 = 30 years;

[0127] (8) Carry out design monitoring and optimization of low cycle fatigue crack growth life of natural gas and hydrogen fuel control valves;

[0128] If τ f ≥τ0, the low-cycle fatigue crack growth calendar life design monitoring of the natural gas and hydrogen fuel control valves is qualified, the low-cycle fatigue crack growth life of the natural gas and hydrogen fuel control valves is under control, and the low-cycle fatigue crack growth life monitoring of the natural gas and hydrogen fuel control valves is completed;

[0129] If τ f <τ0, the low cycle fatigue crack growth calendar life design monitoring of the natural gas and hydrogen fuel control valve fails. The structure of the natural gas and hydrogen fuel control valve is optimized and improved during the design stage, and the structural fillet radius of the relevant parts is increased to reduce the stress level of the cracked part. Steps (1) to (8) are re-executed until τ f ≥τ0.

[0130] In this specific embodiment, the low cycle fatigue crack growth calendar life τ of the natural gas and hydrogen fuel control valve in step (6) is fCompared with the low cycle fatigue crack growth calendar life criterion value τ0, the low cycle fatigue crack growth life monitoring of the fuel control valve under transient variable working conditions is unqualified. The low cycle fatigue crack growth life monitoring results of natural gas and hydrogen fuel control valves are listed in Table 2:

[0131] Table 2

[0132]

[0133] According to steps (1) to (8), the structure of part A of the natural gas and hydrogen fuel control valve is optimized. The fillet radius of this part is 0.5 mm, which is now optimized and adjusted to 2 mm. The results of steps (3) to (5) after optimization and improvement are listed in Table 3:

[0134] Table 3

[0135]

[0136]

[0137] Calculation of low cycle fatigue crack growth calendar life τ for natural gas and hydrogen fuel control valves f , low cycle fatigue crack growth calendar life τ under each transient condition f The calculation result is:

[0138]

[0139] According to the steps, the results of steps (6) to (8) after optimization and improvement are listed in Table 4:

[0140] Table 4

[0141]

[0142] In summary, the method for designing and monitoring the low-cycle fatigue crack growth life of the fuel control valve provided in this specific embodiment realizes the low-cycle fatigue crack growth life design and structural optimization improvement of the fuel control valve of this type of heavy-duty gas turbine. The low-cycle fatigue crack growth life design of the fuel control valve of this type of heavy-duty gas turbine is unqualified under the transient variable working conditions of the gas turbine. By increasing the fillet radius of the structure at part A, the low-cycle fatigue crack growth life of the fuel control valve of this type of heavy-duty gas turbine is under control.

[0143] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for designing and monitoring the low cycle fatigue crack growth life of a fuel control valve, characterized in that: The method is applicable to natural gas and hydrogen fuel control valves, and comprises the following steps: (1) Construct a finite element stress analysis model of the fuel control valve; (2) Determine the material grade and performance parameters of each component of the fuel control valve; (3) Calculation of the maximum stress σ for low-cycle fatigue crack growth in the fuel control valve max ; (4) Calculation of the critical crack size a for low-cycle fatigue crack growth in the fuel control valve c ; (5) Calculation of the low cycle fatigue crack growth life N of the fuel control valve f ; (6) Calculation of the fuel control valve low cycle fatigue crack growth calendar life τ f ; (7) Determine the fuel control valve low cycle fatigue crack growth calendar life criterion value τ0; (8) Carry out design monitoring and optimization of the low-cycle fatigue crack growth life of fuel control valves.

2. The method according to claim 1, characterized in that The performance parameters in step (2) include physical performance parameters and fracture mechanics performance parameters; Preferably, the physical property parameters include density ρ, elastic modulus E, Poisson's ratio υ, linear expansion coefficient α, specific heat capacity Cp and thermal conductivity λ; Preferably, the fracture mechanics performance parameters include fracture toughness K IC , fatigue crack growth threshold ΔK th , material constants C0 and m0 of crack fatigue growth.

3. The method according to claim 1 or 2, characterized in that: The maximum stress σ in step (3) max The calculation formula is: s max =σ1+σ re (1) In the formula, σ re - residual stress of fuel control valve; σ1——The maximum principal stress at the crack site of the fuel control valve under each transient condition; Preferably, the transient operating conditions include hot start, warm start and cold start of the gas turbine.

4. The method according to any one of claims 1 to 3, characterized in that: The critical crack size a in step (4) c The calculation formula is: Where, M is a constant related to crack shape parameters.

5. The method according to any one of claims 1 to 4, characterized in that: Step (5) The fuel control valve low cycle fatigue crack growth life N f The calculation formula is: Where: a i — initial size of the crack; n f ——Safety factor of low cycle fatigue crack growth life; Preferably, during the design phase, a i Take 2mm.

6. The method according to any one of claims 1 to 5, characterized in that: Step (6) The fuel control valve low cycle fatigue crack growth calendar life τ f The calculation formula is: Where: y c ——Annual average number of cold starts; y w ——Annual average number of warm-state starts; y h ——Annual average number of hot starts; N fc - fatigue crack growth life during cold start-up; N fw - fatigue crack growth life during warm starting; N fh ——Fatigue crack growth life during hot start-up.

7. The method according to any one of claims 1 to 6, characterized in that: According to the design requirements of gas turbine power station and fuel control valve, the criterion value τ0 of low cycle fatigue crack growth calendar life of fuel control valve is determined; Preferably, for gas turbine power plants, the design requirement for natural gas and hydrogen fuel control valves is τ0 = 30 years.

8. The method according to any one of claims 1 to 7, characterized in that: The step of carrying out design monitoring and optimization of the low cycle fatigue crack growth life of the fuel control valve in step (8) specifically includes: If τ f ≥τ0, the low-cycle fatigue crack growth calendar life design monitoring of the fuel control valve is qualified, the low-cycle fatigue crack growth life of the fuel control valve is under control, and the low-cycle fatigue crack growth life monitoring of the fuel control valve is completed; If τ f <τ0, the fuel control valve's low-cycle fatigue crack growth calendar life design monitoring fails. The fuel control valve structure is optimized and improved during the design phase, and the structural fillet radius of the relevant parts is increased to reduce the stress level of the cracked parts. Steps (1) to (8) are re-executed until τ f ≥τ0.

9. A fuel control valve low cycle fatigue crack growth life design and monitoring device system, characterized in that: The device system performs the method for designing and monitoring the low cycle fatigue crack growth life of a fuel control valve as described in any one of claims 1 to 8.

10. The device system according to claim 9, characterized in that: The device system includes a modeling module and a data collection module that are independent of each other; Preferably, the modeling module and the data collection module are respectively connected to the analysis and calculation module, the life monitoring module and the optimization and improvement module in sequence.

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