A method for detecting the state of high-temperature bolts in a high-pressure inner cylinder of a steam turbine, a state detection system device and its application

Abstract

The present invention provides a state detection method, state detection system device, and application of high-temperature bolts in a high-pressure inner cylinder of a steam turbine, comprising: (1) establishing a model and determining a boundary; (2) determining a high-temperature location point of the high-temperature bolt; (3) calculating the temperature value of the high-temperature location point of the high-temperature bolt under different working conditions; (4) obtaining a surface function of the transient elongation of the high-temperature bolt; (5) inputting the surface function into a server; (6) calculating the real-time length of the high-temperature bolt in real time; (7) self-correcting the calculation method of the real-time length of the high-temperature bolt; and (8) recommending an operation and maintenance strategy based on the real-time length of the high-temperature bolt. The present invention realizes the real-time calculation of the high-temperature bolt length by establishing a surface function and realizes the self-correction of the calculation method, thereby avoiding the generalization problem of the artificial intelligence model and the problem that the curve function cannot accurately calculate the high-temperature bolt length in real time, and provides a basis for the optimized operation and cylinder overhaul of the high-pressure cylinder.

Description

Technical Field

[0001] The present invention belongs to the technical field of steam turbines and relates to a method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine, a status detection system device and an application thereof. Background Art

[0002] A steam turbine is an externally-combustion rotary machine that converts steam thermal energy into mechanical work. Steam from the boiler enters the turbine and passes through a series of annular nozzles and moving blades, converting the steam's thermal energy into mechanical energy that rotates the turbine rotor. The steam undergoes different energy conversion methods within the turbine, resulting in different operating principles.

[0003] The high-pressure inner cylinder is a component of the steam turbine and is the initial stage for the main steam to enter the cylinder. The high-temperature bolts on the high-pressure inner cylinder of the steam turbine provide tightening force for the center surface of the cylinder, ensuring that the center surface of the cylinder fits tightly and preventing steam leakage from the cylinder. The high-pressure inner cylinder is the component of the steam turbine that withstands the highest steam temperature and pressure. During the long-term operation of the steam turbine, the high-pressure inner cylinder bolts will creep under structural stress and high-temperature working conditions. Creep is an irreversible plastic deformation. After long-term creep, the high-temperature bolts will creep and elongate, the bolt tightening force will decrease, and sufficient compression force will not be provided for the center surface, causing steam leakage from the center surface, resulting in reduced efficiency, and even causing erosion and damage to the center surface of the cylinder, resulting in serious losses.

[0004] Since the high-temperature bolts are located on the high-temperature and high-pressure cylinder flange, their status cannot be directly observed during operation. Traditional technology uses offline measurement of the hardness and elongation of the high-temperature bolts to infer whether the bolts have failed. However, this method is a post-inspection and faces the technical difficulty of being unable to effectively grasp the real-time status of the high-temperature bolts in the high-pressure inner cylinder of the turbine during the operation of the unit. There is no suitable method and system available for online monitoring of the status of the high-temperature bolts in the high-pressure inner cylinder of the turbine. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a state detection method, a state detection system device and an application of the high-temperature bolts of the high-pressure inner cylinder of a steam turbine. The state detection method provided by the present invention uses finite element calculation to establish virtual measuring points, adopts the method of establishing surface functions to realize real-time calculation of the length of the high-temperature bolts, and realizes self-correction of the calculation method, avoiding the generalization problem of the artificial intelligence model and the problem that the curve function cannot accurately calculate the length of the high-temperature bolts in real time, providing a basis for the optimized operation and cylinder overhaul of the high-pressure cylinder.

[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 detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine, the method comprising:

[0008] (1) Establish a three-dimensional model of high-temperature bolts and determine the steady-state thermal boundary under different main steam temperatures t and main steam flow rates Q;

[0009] (2) Carry out temperature field calculation of high-temperature bolts, calculate the temperature distribution of high-temperature bolts under different main steam temperatures t and main steam flow rates Q, and determine several high-temperature locations;

[0010] (3) According to the calculation results of the temperature field, the temperature value t of the high temperature point under different main steam temperatures t and main steam flow rates Q is obtained. hn , establish t hn , the surface function relationship between t and Q is expressed as t hn =f(t,Q);

[0011] (4) Carry out creep field calculation of high temperature bolts at different temperature values t hn Calculate the transient elongation Δl at the high temperature point under the cumulative time d ns , establish Δl ns , t hn The surface function relationship between and d is expressed as Δl ns =g(t hn , d);

[0012] (5) According to the surface function t hn =f(t,Q) and Δl ns =g(t hn , d) Calculate the transient elongation Δl at the high temperature point at different time periods ns , combined with the original length l of the high temperature bolt ny After cumulative calculation, the real-time length l of high-temperature bolts at different time periods is obtained n .

[0013] The state detection method provided by the present invention utilizes finite element calculation to establish virtual measuring points, adopts the method of establishing surface functions to realize real-time calculation of high-temperature bolt length, and realizes self-correction of the calculation method, thereby avoiding the generalization problem of artificial intelligence models and the problem that curve functions cannot accurately calculate the length of high-temperature bolts in real time, and provides a basis for the optimized operation and cylinder overhaul of high-pressure cylinders.

[0014] As a preferred technical solution of the present invention, step (1) specifically includes:

[0015] A three-dimensional model of the high-temperature bolt is established and meshed to obtain the mesh and node model of the high-temperature bolt, and the steady-state thermal boundary and force boundary under different main steam temperatures t and main steam flow rates Q are determined.

[0016] As a preferred technical solution of the present invention, step (2) specifically includes:

[0017] According to the material data of the high-pressure inner cylinder and high-temperature bolts of the steam turbine, the temperature field of the high-pressure inner cylinder and high-temperature bolts of the steam turbine is calculated, and the temperature distribution under different main steam temperatures t and main steam flow rates Q is calculated. Several high-temperature points are determined, and the temperature value of each high-temperature point is recorded as t hn , where n is a positive integer greater than or equal to 1, and the temperature values of the high temperature points are t h1 , t h2 , t h3 , t h4 , t h5 、···。

[0018] Preferably, 3 to 5 high-temperature locations are selected.

[0019] Preferably, the distance between two adjacent high-temperature locations is greater than 5 mm.

[0020] As a preferred technical solution of the present invention, step (3) specifically includes:

[0021] According to the temperature field calculation results of the high-pressure inner cylinder and high-temperature bolts of the steam turbine, the temperature value t of the high-temperature part under different main steam temperatures t and main steam flow rates Q is obtained. hn , establish t through mathematical software hn , the surface function relationship between t and Q is expressed as t hn =f(t,Q).

[0022] Preferably, the mathematical software is Matlab.

[0023] Preferably, the calculation range of the main steam temperature t is determined by the rated main steam temperature t0 of the steam turbine.

[0024] Preferably, the calculated value range of the main steam temperature t is 480°C to t0+50°C.

[0025] Preferably, when the main steam temperature t is within the range of 480°C to t0+50°C, the temperature value t of the high temperature part is calculated every time the main steam temperature t changes by 5°C. hn .

[0026] Preferably, the calculation range of the main steam flow rate Q is determined by the rated main steam flow rate Q0 of the steam turbine;

[0027] Preferably, the calculation value range of the main steam flow Q is 0.05Q0 to 1.2Q0.

[0028] Preferably, when the main steam flow rate Q is within the range of 0.05Q0 to 1.2Q0, the temperature value t of the high temperature part is calculated every time the main steam flow rate Q changes by 0.1Q0. hn .

[0029] As a preferred technical solution of the present invention, step (4) specifically includes:

[0030] Model the high-temperature bolts separately and assign the temperature value t to the high-temperature part of the high-temperature bolts as a whole. hn , at different temperature values t hn Calculate the transient elongation Δl at the high temperature point under the cumulative time d ns , establish Δl ns , t hn The surface function relationship between and d is expressed as Δl ns =g(t hn , d).

[0031] Preferably, the cumulative time d is 1.5 overhaul cycles.

[0032] Preferably, the calculation interval of the cumulative time d is 480 hours.

[0033] As a preferred technical solution of the present invention, step (5) is divided into two steps, including step (5.1) and step (5.2) performed sequentially.

[0034] Step (5.1) includes: transforming the surface function t hn =f(t,Q) and Δl ns =g(t hn , d) stored in the status monitoring server and set t hn The lower limit value, when t hn When the speed n is greater than or equal to the lower limit and the turbine speed n>2800r / min, the transient elongation Δl at the high temperature point is calculated. ns , when t hn When it is less than the lower limit or n<2800r / min, Δl ns Take 0.

[0035] Preferably, the lower limit is 480°C.

[0036] Preferably, step (5.2) includes: retrieving the measurement point data of the high-pressure inner cylinder of the steam turbine in real time and transmitting it to the state monitoring server, and the state monitoring server brings the measurement point data into the surface function t hn =f(t, Q), calculate the temperature value t of the high temperature point hn ; The status monitoring server will take the temperature value of the high temperature point t hn Substitute the surface function Δl ns =g(thn , d), the transient elongation Δl at the high temperature point is calculated ns , calculate the transient elongation Δl every once in a while ns , combined with the original length l of the high temperature bolt ny , for several groups of transient elongation Δl ns After cumulative calculation, the real-time length l of high-temperature bolts at different time periods is obtained n , the calculation formula is l n =l ny +ΣΔl ns .

[0037] Preferably, the measurement point data include main steam temperature t, main steam flow Q, high pressure cylinder inner wall measurement point temperature t gn , turbine speed n and bolt cumulative running time d s .

[0038] Preferably, the temperature value t of the high temperature point is calculated hn When t hn >t, the calculation fails, t hn =f(t, Q) needs to repeat steps (1) to (4) for correction. Before the surface function correction is completed, t hn =t gn .

[0039] Preferably, when calculating the transient elongation Δl ns When the transient elongation Δl is calculated every 1h ns .

[0040] As a preferred technical solution of the present invention, the state detection method further includes step (6), which includes: measuring the real-time length l of the high-temperature bolt n The calculation method is self-corrected.

[0041] Preferably, step (6) specifically includes the following steps:

[0042] Regularly measure the real-time length of high-temperature bolts n The calculation model is verified and the temperature value t of the high temperature point is read. hn , the main steam flow Q and main steam temperature t change curve with time, calibration t hn , Q and t, respectively, are denoted as t hnmax , Q max , t max , according to the cumulative running time d of the bolt s , calculate the maximum elongation l max , if l max <l n , then the surface function t hn=f(t,Q) and Δl ns =g(t hn , d) It is necessary to repeat steps (1) to (4) for correction. Before the surface function correction is completed, l n =l max .

[0043] As a preferred technical solution of the present invention, the state detection method further includes step (7), which includes: according to the real-time length l of the high-temperature bolt n The elongation limit value of high temperature bolts l bz Make comparisons and adopt different operation and maintenance strategies based on the comparison results.

[0044] Preferably, step (7) specifically includes the following steps:

[0045] Take the maximum real-time length l of the high-temperature bolt under different working conditions a , will l a The elongation limit value of high temperature bolts l bz Perform a comparison and adopt different operation and maintenance strategies based on the comparison results:

[0046] If l a ≤0.7l bz , the steam turbine operates normally;

[0047] If 0.7l bz <l a ≤0.8l bz , the main steam is prone to overheating, optimize the operation and try to avoid main steam overheating;

[0048] If 0.8l bz <l a ≤1.2l bz , formulate a cylinder maintenance plan and arrange shutdown maintenance in a timely manner;

[0049] If l a >1.2l bz , arrange maintenance as soon as possible, open the high-pressure inner cylinder of the turbine, check the condition of the high-temperature bolts, and replace the high-temperature bolts if necessary.

[0050] In a second aspect, the present invention provides a status detection system device for performing the status detection method for high-temperature bolts of a high-pressure inner cylinder of a steam turbine described in the first aspect. The status detection system device includes a DCS engineer station, a parameter database server, a status monitoring server, a web server and a user-end browser electrically connected in sequence. The parameter database server is used to retrieve existing measurement point data from the power plant DCS workstation and transmit it to the status monitoring server.

[0051] In a third aspect, the present invention provides an application of the state detection method described in the first aspect, wherein the state detection method is used to continuously monitor the working state of the high-temperature bolts of the high-pressure inner cylinder of the steam turbine online.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The state detection method provided by the present invention utilizes finite element calculation to establish virtual measuring points, adopts the method of establishing surface functions to realize real-time calculation of high-temperature bolt length, and realizes self-correction of the calculation method, thereby avoiding the generalization problem of artificial intelligence models and the problem that curve functions cannot accurately calculate the length of high-temperature bolts in real time, and provides a basis for the optimized operation and cylinder overhaul of high-pressure cylinders. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 A schematic structural diagram of a status monitoring system device provided in accordance with a specific embodiment of the present invention;

[0055] Figure 2 A flow chart of a state monitoring method provided in one embodiment of the present invention;

[0056] Figure 3 This is a logic block diagram of a software algorithm within a status monitoring server provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0057] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0058] In a specific embodiment, the present invention provides a state detection system device for high-temperature bolts in a high-pressure inner cylinder of a steam turbine, such as Figure 1 As shown, the status detection system device includes a DCS engineer station, a parameter database server, a status monitoring server, a web server and a user browser that are electrically connected in sequence. The parameter database server is used to retrieve existing measurement point data from the power plant DCS workstation and transmit it to the status monitoring server.

[0059] In another specific embodiment, the present invention provides a method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine. Figure 2 As shown, the state detection method specifically includes the following steps:

[0060] (1) Build a model and determine the boundaries

[0061] A three-dimensional model of the steam turbine's high-pressure inner cylinder and its associated high-temperature bolts was established and meshed, resulting in a mesh and node model of the high-pressure inner cylinder's high-temperature bolts. Based on the design data, the steady-state thermal and force boundaries were determined for different main steam temperatures t and main steam flow rates Q.

[0062] (2) Determine the high temperature point of the high temperature bolt

[0063] Input the material data of the high-pressure inner cylinder and high-temperature bolts, and carry out the temperature field calculation of the high-pressure inner cylinder of the steam turbine and its high-temperature bolts. Calculate the temperature distribution of the high-temperature bolts under different main steam temperatures t and main steam flow rates Q, and determine 3 to 5 high-temperature points of the high-temperature bolts. The temperature value of the high-temperature point is recorded as t hn (n is 1, 2, 3, 4, 5), the distance between each high temperature point is at least greater than 5mm;

[0064] (3) Calculate the temperature value t of the high temperature part of the high temperature bolt under different working conditions hn

[0065] According to the temperature field calculation results of the high-pressure inner cylinder of the steam turbine and its high-temperature bolts, the temperature value t of the high-temperature part of the high-temperature bolt under different main steam temperatures t and main steam flow rates Q is obtained. hn , through mathematical software (Matlab, etc.), establish t hn The surface function of t and Q, the functional relationship is t hn =f(t, Q), the calculation range of t is determined by the rated main steam temperature t0 of the turbine. The preferred calculation range is 480℃~t0+50℃, and a temperature value t is calculated every 5℃. hn The calculation range of Q is determined by the rated main steam flow rate Q0 of the turbine. The calculation range is 0.05Q0~1.2Q0, and a temperature value t is calculated every 0.1Q0. hn ;

[0066] (4) Obtain the transient elongation Δl of the high-temperature bolt ns Surface function

[0067] The high-temperature bolt is modeled separately, and the temperature value t of the high-temperature part of the high-temperature bolt is assigned to the entire bolt. hn , carry out creep field calculation of high temperature bolts, calculate the creep field of bolts at different temperature values t hn Under high temperature conditions, the transient elongation of the bolt at the high temperature point is Δl ns The relationship between Δl and the cumulative time d is established ns With t hn The surface function between , d, is marked as Δl ns =g(t hn , d), the calculation interval of the cumulative time d is 480 hours (20 days), and the cumulative time d is calculated to 1.5 overhaul cycles. For example: if the overhaul cycle is 50,000 hours, it is calculated to 75,000 hours;

[0068] (5) Surface function input server

[0069] The surface function thn =f(t,Q) and Δl ns =g(t hn , d) stored in the status monitoring server, and set t hn The lower limit is usually set at 480℃. hn When the calculation lower limit is reached (greater than or equal to the lower limit) and the turbine speed n>2800r / min, the calculation of the transient elongation Δl of the high-temperature bolt at the high-temperature position is started. ns , when t hn When it is less than the lower limit or n<2800 rpm, Δl ns =0;

[0070] (6) Real-time calculation of the real-time length l of high-temperature bolts n

[0071] The database server retrieves the existing measurement point data from the power plant DCS workstation in real time, including the main steam temperature t, main steam flow Q, and the high-pressure cylinder inner wall measurement point temperature t gn , turbine speed n and bolt cumulative running time d s , and input it to the status monitoring server, and the status monitoring server calculates the temperature value t of the high temperature point hn (If t hn >t, the calculation fails, t hn Take t gn Temperature value, t hn =f(t, Q) surface function needs to be revised) and calculate the transient elongation Δl of the high temperature point ns , calculate the transient elongation Δl once every hour ns , and Δl ns Accumulate and get the real-time length l of the high-temperature bolt n =l ny +ΣΔl ns , where l ny The original length of the high-temperature bolt measured during maintenance;

[0072] (7) Real-time length of high-temperature bolts l n Self-correction of calculation method

[0073] The status monitoring server regularly (recommended interval is 1 month) measures the real-time length of high-temperature bolts. n The calculation model is verified and the temperature value t of the high temperature point is read from the status monitoring server. hn , the main steam flow Q, the main steam temperature t change curve with time, calibration t hn The maximum values of Q and t are respectively denoted as th nmax , Q max and t max, according to the cumulative running time d of the bolt s , calculate the maximum elongation l of high temperature bolts max , if l max <l n , then the surface function t hn =f(t,Q) and Δl ns =g(thn, d) needs to be corrected. Before the surface function correction is completed, l n =l max ;

[0074] (8) Recommendation of operation and maintenance strategies based on the real-time length of high-temperature bolts

[0075] The limit value of bolt elongation l provided by the manufacturer bz Based on this, take the maximum value l obtained by calculation a , l a =max{l1, l2, ...l n}Recommendation on steam turbine operation and maintenance strategy:

[0076] If l a ≤0.7l bz , the steam turbine operates normally;

[0077] If 0.7l bz <l a ≤0.8l bz , the main steam is prone to overheating, optimize the operation and try to avoid main steam overheating;

[0078] If 0.8l bz <l a ≤1.2l bz , formulate a cylinder maintenance plan and arrange shutdown maintenance in a timely manner;

[0079] If l a >1.2l bz , arrange maintenance as soon as possible, open the high-pressure inner cylinder of the turbine, check the condition of the high-temperature bolts, and replace the high-temperature bolts if necessary.

[0080] The state detection method provided by the present invention utilizes finite element calculation to establish virtual measuring points, adopts the method of establishing surface functions to realize real-time calculation of high-temperature bolt length, and realizes self-correction of the calculation method, thereby avoiding the generalization problem of artificial intelligence models and the problem that curve functions cannot accurately calculate the length of high-temperature bolts in real time, and provides a basis for the optimized operation and cylinder overhaul of high-pressure cylinders.

[0081] In another embodiment, the present invention provides a Figure 3 The software algorithm shown is written into the status monitoring server. The logic algorithm specifically includes the following steps:

[0082] S1. Input the main steam temperature t, main steam flow Q, and high-pressure cylinder inner wall measuring point temperature t into the status monitoring server. gn , turbine speed n and bolt cumulative running time d s The monitoring value goes to step S2;

[0083] S2, the state monitoring server brings the measurement point data into the surface function t hn =f(t, Q), calculate the temperature value t of the high temperature point hn , go to step S3 and perform logical judgment;

[0084] S3. Determine the temperature value t of the high temperature point hn Is it less than the main steam temperature t? If the judgment result is yes, go to step S4; if the judgment result is no, then the temperature of the high-pressure cylinder inner wall measuring point t gn Assign to t hn , and proceed to step S8;

[0085] S4, the temperature value of the high temperature point t hn Substitute the surface function Δl ns =g(t hn , d), the transient elongation Δl at the high temperature point is calculated ns , calculate the transient elongation Δl every once in a while ns , combined with the original length l of the high temperature bolt ny , for several groups of transient elongation Δl ns After cumulative calculation, the real-time length l of high-temperature bolts at different time periods is obtained n ;

[0086] S5. Calculate the maximum elongation of high temperature bolts l max , go to step S6 and perform logical judgment;

[0087] S6. Determine the maximum elongation of high temperature bolts l max Is it greater than the real-time length l? n If the judgment result is yes, then go to step S7; if the judgment result is no, then set the maximum elongation l max Assign to l n , and proceed to step S8;

[0088] S7, according to the real-time length of high-temperature bolts l n The elongation limit value of high temperature bolts l bz Perform a comparison, adopt different operation and maintenance strategies based on the comparison results, and proceed to step S9;

[0089] S8, return to step S2, and calculate the surface function t hn =f(t,Q) and Δlns =g(t hn , d) make corrections;

[0090] S9. The program ends.

[0091] Example 1

[0092] For a certain subcritical 300MW steam turbine high-pressure inner cylinder, the steam inlet temperature is 537°C and the rated steam inlet flow is 934.58 t / h. The method for monitoring the status of high-temperature bolts in the high-pressure inner cylinder of a steam turbine provided by the present invention is used to implement status monitoring and operation and maintenance strategy recommendations for the high-temperature bolts in the high-pressure inner cylinder of this subcritical 300MW steam turbine. The specific steps are as follows:

[0093] (1) Build a model and determine the boundaries

[0094] A three-dimensional model of the subcritical 300MW steam turbine high-pressure inner cylinder and its high-temperature bolts was established and meshed. The mesh and node model of the high-temperature bolts of the subcritical 300MW steam turbine high-pressure inner cylinder was obtained and the thermal and force boundaries of the steady-state working condition were determined.

[0095] (2) Determine the high temperature point of the high temperature bolt

[0096] Input the material data of the high-pressure inner cylinder and high-temperature bolts of a subcritical 300MW steam turbine, carry out the temperature field calculation of the high-pressure inner cylinder of the steam turbine and its high-temperature bolts, calculate the temperature distribution of the high-temperature bolts under different main steam temperatures t and main steam flow rates Q, select the high-temperature bolt with the highest temperature, and determine the four high-temperature points of the high-temperature bolt. The temperature value of the high-temperature point is recorded as t h1 , t h2 , t h3 , t h4 , the minimum distance between each high-temperature point is 7mm;

[0097] (3) Calculate the temperature value t of the high temperature part of the high temperature bolt under different working conditions hn

[0098] According to the temperature field calculation results of the high-pressure inner cylinder of the steam turbine and its high-temperature bolts, the temperature value t of the high-temperature part of the high-temperature bolt under different main steam temperatures t and main steam flow rates Q is obtained. hn , through mathematical software (Matlab, etc.), establish t hn The surface function of t and Q, the functional relationship is t hn =f(t, Q), the calculation range of t is 480℃~585℃, and a temperature value t is calculated every 5℃ hn The calculation range of Q is 46.729t / h~1121.496t / h, and a temperature value t is calculated every 93.458t / h.hn ;

[0099] (4) Obtain the transient elongation Δl of the high-temperature bolt ns of the surface function

[0100] Model the high-temperature bolt separately, and assign the temperature value t of the high-temperature part points of the bolt to the whole bolt hn , conduct the creep field calculation of the high-temperature bolt, and calculate the transient elongation Δl of the bolt at the high-temperature part points of the bolt at different temperature values t hn Under the condition, establish the relationship between the transient elongation Δl of the bolt at the high-temperature part points and the cumulative time d, and establish the surface function between Δl ns and t ns and d (n = 1, 2, 3, 4), and the functional relationship is Δl hn = g(t ns , d), the calculation interval of the cumulative time d is 480 hours (20 days), and the cumulative time d is calculated up to 65700 hours; hn

[0101] (5) Input the surface function into the server

[0102] Store the surface functions t[[ID=u30]] hn = f(t, Q) and Δl ns = g(t hn , d) in the state monitoring server, and set the lower limit value of t hn , the lower limit value is set to 480 °C. When t hn reaches the calculation lower limit value (greater than or equal to 480 °C) and the steam turbine speed n > 2800 r / min, start to calculate the transient elongation Δl of the bolt at the high-temperature part points of the high-temperature bolt ns . When t hn is less than 480 °C or n < 2800 r / min, Δl ns = 0;

[0103] (6) Calculate the real-time length l of the high-temperature bolt in real time n

[0104] The database server retrieves the existing measured point data from the power plant DCS workstation in real time, including the main steam temperature t, the main steam flow Q, the measured point temperature t on the inner wall of the high-pressure cylinder gn , the steam turbine speed n and the bolt cumulative operation time d s , and inputs them into the state monitoring server. After calculation by the state monitoring server, the temperature value t of the high-temperature part points is obtained hn , and t hn < t, the calculation is valid, and calculate the transient elongation Δl 1s , Δl 2s , Δl 3s and Δl 4s ​, calculate the transient elongation Δl once every hour ns , and Δl ns Accumulate and get the real-time length l of the high-temperature bolt n Finally, the real-time lengths of the high-temperature bolts are l1=530.32mm, l2=532.11mm, l3=535.84mm, and l4=537.77mm, which are all less than the calculated maximum elongation l max =550.13mm, the calculation result is valid, l a =max{l1, l2, l3, l4}=542.77mm;

[0105] (7) Recommendation of operation and maintenance strategies based on the real-time length of high-temperature bolts

[0106] The limit value of the elongation of high-temperature bolts provided by the manufacturer is l bz =680mm, l a <0.8l bz , it is necessary to pay attention to the overheating of the main steam, optimize the operation, and try to avoid overheating of the main steam.

[0107] By adopting the method for monitoring the status of high-temperature bolts in the high-pressure inner cylinder of a steam turbine provided by the present invention, the status of the high-temperature bolts in the high-pressure inner cylinder of the steam turbine is monitored, and operation and maintenance are optimized according to the existing status of the high-temperature bolts, thereby improving the safety of the 300MW steam turbine and scientifically arranging high-pressure cylinder maintenance projects.

[0108] Example 2

[0109] For a certain model of supercritical 640MW steam turbine high-pressure inner cylinder, the steam inlet temperature is 566°C and the rated steam inlet flow is 1712.088 t / h. The method for monitoring the status of high-temperature bolts in the high-pressure inner cylinder of the steam turbine provided by the present invention is used to implement status monitoring and operation and maintenance strategy recommendation for the high-temperature bolts in the high-pressure inner cylinder of this model of supercritical 640MW steam turbine. The specific steps are as follows:

[0110] (1) Build a model and determine the boundaries

[0111] A three-dimensional model of the high-pressure inner cylinder and its high-temperature bolts of a supercritical 640MW steam turbine was established and meshed. The mesh and node model of the high-pressure inner cylinder and high-temperature bolts of the supercritical 640MW steam turbine were obtained, and the thermal and force boundaries of the steady-state working condition were determined.

[0112] (2) Determine the high temperature point of the high temperature bolt

[0113] Input the material data of the high-pressure inner cylinder and high-temperature bolts of a supercritical 640MW steam turbine, carry out the temperature field calculation of the high-pressure inner cylinder of the steam turbine and its high-temperature bolts, calculate the temperature distribution of the high-temperature bolts under different main steam temperatures t and main steam flow rates Q, select the high-temperature bolt with the highest temperature, and determine the three high-temperature locations of the high-temperature bolt. The temperature value of the high-temperature location is recorded as t h1 , t h2 , t h3 , the minimum distance between each high-temperature point is 6.2mm;

[0114] (3) Calculate the temperature value t of the high temperature part of the high temperature bolt under different working conditions hn

[0115] According to the temperature field calculation results of the high-pressure inner cylinder of the steam turbine and its high-temperature bolts, the temperature value t of the high-temperature part of the high-temperature bolt under different main steam temperatures t and main steam flow rates Q is obtained. hn , through mathematical software (Matlab, etc.), establish t hn The surface function of t and Q, the functional relationship is t hn =f(t, Q), the calculation range of t is 480℃~585℃, and a temperature value t is calculated every 5℃ hn The calculation range of Q is 85.6044t / h~2054.5056t / h, and a temperature value t is calculated every 171.2t / h. hn ;

[0116] (4) Obtain the transient elongation Δl of the high-temperature bolt ns Surface function

[0117] The high-temperature bolt is modeled separately, and the temperature value t of the high-temperature part of the high-temperature bolt is assigned to the entire bolt. hn , carry out creep field calculation of high temperature bolts, calculate the creep field of bolts at different temperature values t hn Under high temperature conditions, the transient elongation of the bolt at the high temperature point is Δl ns The relationship between Δl and the cumulative time d is established ns With t hn The surface function between , d (n = 1, 2, 3), the functional relationship is Δl ns =g(t hn , d), the calculation interval of the cumulative time d is 480 hours (20 days), and the cumulative time d is calculated to 105120 hours;

[0118] (5) Surface function input server

[0119] The surface function t hn =f(t,Q) and Δl ns =g(t hn, d) stored in the status monitoring server, and set t hn The lower limit value of is set to 480 °C. When t hn reaches the calculated lower limit value (greater than or equal to 480 °C) and the steam turbine speed n > 2800 r / min, start calculating the bolt transient elongation Δl of the high-temperature part points of the high-temperature bolts ns When t hn is less than 480 °C or n < 2800 r / min, Δl ns = 0;

[0120] (6) Real-time calculation of the real-time length l of the high-temperature bolts n

[0121] The database server retrieves the existing measurement point data in real time from the power plant DCS workstation, including the main steam temperature t, the main steam flow Q, the temperature t of the inner wall measurement point of the high-pressure cylinder gn , the steam turbine speed n and the bolt cumulative operation time d s , and inputs them into the status monitoring server. After calculation by the status monitoring server, the temperature value t of the high-temperature part points is obtained hn , and t hn < t, the calculation is valid, and the bolt transient elongation Δl 1s , Δl 2s and Δl 3s are calculated. The bolt transient elongation Δl ns is calculated once per hour, and Δl ns is accumulated to obtain the real-time length l of the high-temperature bolts n [[ID = 37]], and finally the real-time lengths of the current high-temperature bolts are obtained as l1 = 610.56 mm, l2 = 612.58 mm, l3 = 609.45.84 mm, all of which are less than the calculated maximum elongation l max = 650.13 mm, the calculation result is valid, l a = max{l1, l2, l3} = 612.58 mm;

[0122] (7) Recommendation of operation and maintenance strategies based on the real-time length of high-temperature bolts

[0123] The elongation limit value l of the high-temperature bolts provided by the manufacturer bz = 610 mm, l a <1.2l bz , it is necessary to start formulating a cylinder-opening overhaul plan and arrange shutdown overhaul in a timely manner.

[0124] By adopting the method for monitoring the status of high-temperature bolts in the high-pressure inner cylinder of a steam turbine provided by the present invention, the status of the high-temperature bolts in the high-pressure inner cylinder of the steam turbine is monitored, and operation and maintenance are optimized according to the existing status of the high-temperature bolts, thereby improving the safety of the 640MW steam turbine and scientifically arranging high-pressure cylinder maintenance projects.

[0125] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection 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 fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine, characterized in that: The state detection method includes: (1) Establish a three-dimensional model of the high-temperature bolt and determine the steady-state thermal boundary under different main steam temperatures t and main steam flow rates Q; (2) Carry out temperature field calculation of high-temperature bolts, calculate the temperature distribution of high-temperature bolts under different main steam temperatures t and main steam flow rates Q, and determine several high-temperature locations; (3) According to the calculation results of the temperature field, the temperature value t of the high-temperature point under different main steam temperatures t and main steam flow rates Q is obtained. hn , establish t hn , the surface function relationship between t and Q is expressed as t hn =f(t,q); (4) Carry out creep field calculation of high temperature bolts at different temperature values t hn Calculate the transient elongation Δl at the high temperature point under the cumulative time d ns , establish Δl ns , t hn The surface function relationship between and d is expressed as Δl ns =g(t hn , d); (5) According to the surface function t hn =f(t,Q) and Δl ns =g(t hn , d) Calculate the transient elongation Δl at the high temperature point at different time periods ns , combined with the original length l of the high temperature bolt ny After cumulative calculation, the real-time length l of high-temperature bolts at different time periods is obtained n ; Step (5) is divided into two steps, including step (5.1) and step (5.2) performed in sequence; Step (5.1) includes: transforming the surface function t hn =f(t,Q) and Δl ns =g(t hn , d) stored in the status monitoring server and set t hn The lower limit value, when t hn When the speed n is greater than or equal to the lower limit and the turbine speed n>2800r / min, the transient elongation Δl at the high temperature point is calculated. ns , when t hn When it is less than the lower limit or n<2800r / min, Δl ns Take 0; The lower limit is 480°C; Step (5.2) includes: retrieving the measurement point data of the high-pressure inner cylinder of the steam turbine in real time and transmitting it to the state monitoring server, which then inputs the measurement point data into the surface function t hn =f(t, Q), calculate the temperature value t of the high temperature point hn ; The status monitoring server will take the temperature value of the high temperature point t hn Substitute the surface function Δl ns =g(t hn , d), the transient elongation Δl at the high temperature point is calculated ns , calculate the transient elongation Δl every once in a while ns , combined with the original length l of the high temperature bolt ny , for several groups of transient elongation Δl ns After cumulative calculation, the real-time length l of high-temperature bolts at different time periods is obtained n , the calculation formula is l n =l ny +ΣΔl ns ; The measurement point data include main steam temperature t, main steam flow Q, high pressure cylinder inner wall measurement point temperature t gn , turbine speed n and bolt cumulative running time d s ; Calculate the temperature value t at the high temperature point hn When t hn >t, the calculation fails, t hn =f(t, Q) needs to repeat steps (1) to (4) for correction. Before the surface function correction is completed, t hn =t gn ; In calculating the transient elongation Δl ns When the transient elongation Δl is calculated every 1h ns ; The state detection method further includes step (6), which specifically includes the following steps: Regularly measure the real-time length of high-temperature bolts n The calculation model is verified and the temperature value t of the high temperature point is read. hn , the main steam flow Q and main steam temperature t change curve with time, calibration t hn , Q and t, respectively, are denoted as t hnmax , Q max and t max , according to the cumulative running time d of the bolt s , calculate the maximum elongation l max , if l max <l n , then the surface function t hn =f(t,Q) and Δl ns =g(t hn , d) It is necessary to repeat steps (1) to (4) for correction. Before the surface function correction is completed, l n =l max .

2. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: Step (1) specifically includes: A three-dimensional model of the high-temperature bolt is established and meshed to obtain the mesh and node model of the high-temperature bolt, and the steady-state thermal boundary and force boundary under different main steam temperatures t and main steam flow rates Q are determined.

3. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: Step (2) specifically includes: According to the material data of the high-pressure inner cylinder and high-temperature bolts of the steam turbine, the temperature field of the high-pressure inner cylinder and high-temperature bolts of the steam turbine is calculated, and the temperature distribution under different main steam temperatures t and main steam flow rates Q is calculated. Several high-temperature points are determined, and the temperature value of each high-temperature point is recorded as t hn , where n is a positive integer greater than or equal to 1, and the temperature values of the high temperature points are t h1 , t h2 , t h3 , t h4 , t h5 、···。 4. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: The high-temperature locations are 3 to 5 in number.

5. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: The distance between two adjacent high-temperature locations is greater than 5 mm.

6. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: Step (3) specifically includes: According to the temperature field calculation results of the high-pressure inner cylinder and high-temperature bolts of the steam turbine, the temperature value t of the high-temperature part under different main steam temperatures t and main steam flow rates Q is obtained. hn , establish t through mathematical software hn , the surface function relationship between t and Q is expressed as t hn =f(t,Q).

7. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 6, characterized in that: The mathematical software is Matlab.

8. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: The calculation range of the main steam temperature t is determined by the rated main steam temperature t0 of the turbine.

9. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 8, characterized in that: The calculation range of the main steam temperature t is 480°C~t0+50°C.

10. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 8, characterized in that: When the main steam temperature t is within the range of 480℃~t0+50℃, the temperature value t of the high temperature part is calculated every time the main steam temperature t changes by 5℃. hn .

11. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: The calculation range of the main steam flow rate Q is determined by the rated main steam flow rate Q0 of the steam turbine.

12. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 11, characterized in that: The calculation value range of the main steam flow Q is 0.05Q0~1.2Q0.

13. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 11, characterized in that: When the main steam flow rate Q is within the range of 0.05Q0~1.2Q0, the temperature value t of the high temperature part is calculated every time the main steam flow rate Q changes by 0.1Q0. hn .

14. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: Step (4) specifically includes: Model the high-temperature bolts separately and assign the temperature value t to the high-temperature part of the high-temperature bolts as a whole. hn , at different temperature values t hn Calculate the transient elongation Δl at the high temperature point under the cumulative time d ns , establish Δl ns , t hn The surface function relationship between and d is expressed as Δl ns =g(t hn , d).

15. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: The cumulative time d is 1.5 overhaul cycles.

16. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: The calculation interval of the cumulative time d is 480 hours.

17. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 1, characterized in that: The state detection method further includes step (7), which includes: according to the real-time length l of the high-temperature bolt n The elongation limit value of high temperature bolts l bz Make comparisons and adopt different operation and maintenance strategies based on the comparison results.

18. The method for detecting the status of high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to claim 17, characterized in that: Step (7) specifically includes the following steps: Take the maximum real-time length l of the high-temperature bolt under different working conditions a , will l a The elongation limit value of high temperature bolts l bz Perform a comparison and adopt different operation and maintenance strategies based on the comparison results: If l a ≤0.7l bz , the steam turbine operates normally; If 0.7l bz <l a ≤0.8l bz , the main steam is prone to overheating, optimize the operation and try to avoid main steam overheating; If 0.8l bz <l a ≤1.2l bz , formulate a cylinder maintenance plan and arrange shutdown maintenance in a timely manner; If l a >1.2l bz , arrange maintenance as soon as possible, open the high-pressure inner cylinder of the turbine, check the condition of the high-temperature bolts and replace the high-temperature bolts.

19. A state detection system device for performing the state detection method for high-temperature bolts in a high-pressure inner cylinder of a steam turbine according to any one of claims 1 to 18, characterized in that: The state detection system device includes a DCS engineer station, a parameter database server, a state monitoring server, a web server and a user browser that are electrically connected in sequence. The parameter database server is used to retrieve existing measurement point data from the power plant DCS workstation and transmit it to the state monitoring server.

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