Power station boiler membrane water wall stress monitoring method and system

Abstract

The invention discloses a power station boiler membrane water wall stress monitoring method and system. The power station boiler membrane water wall stress monitoring method comprises the steps that the water wall temperature T between a starting point A and an end point B of the monitoring range of a power station boiler membrane water wall and the actual thermal expansion amount between the starting point A and the end point B are obtained; mapping the temperature T of the water cooling wall into a theoretical thermal expansion amount between a starting point A and an end point B of a monitoring range; and calculating the water wall stress in the monitoring range according to the theoretical thermal expansion amount and the actual thermal expansion amount between the starting point A and the terminal point B of the monitoring range. The method aims at achieving calculation and monitoring of the local stress of the water cooling wall in the boiler operation process so as to help operators to grasp the stress condition of the water cooling wall in real time, guide operation adjustment and guarantee unit peak regulation operation safety.

Description

Technical Field

[0001] This invention relates to the field of power plant boiler safety monitoring technology, specifically to a method and system for monitoring stress in the membrane water-cooled wall of a power plant boiler. Background Technology

[0002] Water-cooled walls in power plant boilers typically employ membrane wall structures. Adjacent tubes are connected by fins to form the combustion chamber, providing space for fuel combustion and absorbing the heat generated during combustion, transferring it to the working fluid inside the tubes to achieve energy transfer. Due to the large size of membrane water-cooled walls, they are susceptible to stress caused by inconsistent expansion or localized obstruction due to thermal expansion. When this stress exceeds the allowable limits of the water-cooled wall material, it can lead to tensile cracking, thus affecting the safe operation of the power plant boiler. Currently, influenced by the demand for grid load regulation, thermal power units have transformed from basic guaranteed power sources to system-regulating power sources. High-frequency and wide-load regulation has become the new normal. Due to deviations from the unit's design operating conditions, peak-shaving operation affects the safety of water-cooled walls. One of the main reasons is that inconsistent expansion during operation leads to stress cracking. Specifically: 1. Under low load, the feedwater flow rate is low. Due to the deterioration of hydrodynamic characteristics, the working fluid flow rate distributed to each pipe is different, resulting in different cooling conditions, which leads to increased temperature difference and increased thermal stress; 2. Under low load, the flue gas filling degree of the furnace deteriorates, and the uniformity of heat load decreases, resulting in different heat absorption of water-cooled walls in different areas, leading to increased temperature difference and increased thermal stress; 3. During rapid load changes, the rate and magnitude of increase and decrease in heat load of water-cooled walls in different areas are different, leading to increased temperature difference and increased thermal stress. Due to technological limitations, thermal stress is difficult to observe. The current expansion indicator method can only observe the overall expansion of the heated surface. Usually, the cause of stress is analyzed and the location of thermal stress is inferred only after the water-cooled wall cracks. It is impossible to achieve real-time monitoring of local thermal stress, and therefore it is impossible to take measures to prevent cracking accidents when thermal stress occurs. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and system for monitoring the stress of membrane water-cooled walls in power plant boilers, in order to help operators grasp the stress status of water-cooled walls in real time, guide operation adjustments, and ensure the safe operation of the unit during peak shaving.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for monitoring stress in a membrane water-cooled wall of a power plant boiler includes the following steps: S101, Obtain the water-cooled wall temperature T between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler, as well as the actual thermal expansion between the starting point A and the ending point B. ; S102 maps the water-cooled wall temperature T to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. ; S103, based on the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. and actual thermal expansion The stress in the water-cooled wall within the monitoring range was calculated.

[0005] Optionally, step S101 includes obtaining the fin center temperature T1 at the starting point A and the fin center temperature T2 at the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler through thermocouples, and calculating the average value of the fin center temperature T1 at the starting point A and the fin center temperature T2 at the ending point B as the water-cooled wall temperature T between the starting point A and the ending point B of the monitoring range.

[0006] Optionally, step S101 includes obtaining the distance from the starting point A of the monitoring range of the power plant boiler membrane water-cooled wall to a fixed reference object using a rangefinder. And the distance from endpoint B to the fixed reference point. Calculate the distance from the starting point A to the fixed reference object. and the distance from endpoint B to the fixed reference point The difference between them is taken as the actual measured distance between the starting point A and the ending point B. The actual measured distance Subtract the initial distance Obtain the actual thermal expansion between the starting point A and the ending point B. The initial distance This refers to the distance between the starting point A and the ending point B of the monitoring range for the membrane water-cooled wall of the power plant boiler in a non-operating environment.

[0007] Optionally, in step S102, the water-cooled wall temperature T is mapped to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. This refers to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range, which is mapped to the water-cooled wall temperature T according to the following formula. : ; in, and These are the fitting parameters.

[0008] Optionally, before step S102, the method further includes pre-fitting to obtain fitting parameters. and : S201, Establish a heat transfer simulation model for the membrane water-cooled wall of a power plant boiler; S202, in the simulation software, the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler at different water-cooled wall temperatures T is obtained through simulation of the heat transfer simulation model. ; S203 represents the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of a power plant boiler at different water-cooled wall temperatures T. To fit Thus, the fitting parameters are obtained. and .

[0009] Optionally, in step S102, the water-cooled wall temperature T is mapped to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. Time refers to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range, obtained by using a pre-trained machine learning model to predict the water-cooled wall temperature T. The inputs to the machine learning model include the water-cooled wall temperature T, the fin center temperature T1 at starting point A, the fin center temperature T2 at ending point B, and the material elastic modulus of the membrane water-cooled wall of the power plant boiler. and the actual measured distance between the starting point A and the ending point B The output of the machine learning model is the predicted theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. The machine learning model establishes a mapping relationship between inputs and outputs for pre-training.

[0010] Optionally, in step S103, the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range is used. and actual thermal expansion The functional expression for the stress in the water-cooled wall within the monitoring range is calculated as follows: ; in, To monitor the stress in the water-cooled wall within the monitoring range, The elastic modulus of the membrane water-cooled wall material for power plant boilers. This refers to the actual measured distance between the starting point A and the ending point B of the monitoring range.

[0011] The present invention also provides a stress monitoring system for a membrane water-cooled wall of a power plant boiler, comprising a microprocessor and a memory interconnected thereto, wherein the microprocessor is programmed or configured to execute the stress monitoring method for the membrane water-cooled wall of the power plant boiler.

[0012] The present invention also provides a computer-readable storage medium storing a computer program or instructions that are programmed or configured to execute the stress monitoring method for the membrane water-cooled wall of a power plant boiler via a processor.

[0013] The present invention also provides a computer program product, including a computer program or instructions, which are programmed or configured to execute the stress monitoring method for the membrane water-cooled wall of the power plant boiler via a processor.

[0014] Compared with the prior art, the present invention mainly achieves the following beneficial effects: the stress monitoring method for membrane water-cooled walls of power plant boilers of the present invention obtains the water-cooled wall temperature T between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler, as well as the actual thermal expansion between the starting point A and the ending point B. Map the water-cooled wall temperature T to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. Based on the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. and actual thermal expansion The stress of the water-cooled wall within the monitoring range is calculated. This invention's method for monitoring the stress of a power plant boiler membrane water-cooled wall measures the temperature and distance between two adjacent points on the membrane water-cooled wall. The theoretical expansion of the water-cooled wall between these two points is calculated based on the temperature, and compared with the actual measured expansion to calculate the thermal stress. This allows for monitoring of local water-cooled wall stress and obtaining the stress distribution. It enables the calculation and monitoring of local water-cooled wall stress during boiler operation, helping operators to understand the water-cooled wall stress in real time during power plant boiler load regulation, guiding operational adjustments, and ensuring the safe operation of the unit during peak shaving. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the basic process of the method in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the sensor arrangement for water-cooled wall stress monitoring in an embodiment of the present invention.

[0017] Figure 3 The temperature distribution of the water-cooled wall tubes in the heat transfer simulation model of this invention embodiment.

[0018] Figure 4 The theoretical expansion distribution of the water-cooled wall in the heat transfer simulation model of this invention embodiment.

[0019] Figure 5 The temperature distribution of the water-cooled wall tube is obtained by simulation under experimental conditions in this embodiment of the invention.

[0020] Figure 6The theoretical expansion distribution of the water-cooled wall is obtained by simulation under experimental conditions in this embodiment of the invention. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings in the embodiments of the present invention.

[0022] like Figure 1 As shown, the stress monitoring method for the membrane water-cooled wall of a power plant boiler in this embodiment includes the following steps: S101, Obtain the water-cooled wall temperature T between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler, as well as the actual thermal expansion between the starting point A and the ending point B. ; S102 maps the water-cooled wall temperature T to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. ; S103, based on the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. and actual thermal expansion The stress in the water-cooled wall within the monitoring range was calculated.

[0023] like Figure 2 As shown, in step S101 of this embodiment, the fin center temperature T1 at the starting point A and the fin center temperature T2 at the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler are obtained by thermocouples, and the average value of the fin center temperature T1 at the starting point A and the fin center temperature T2 at the ending point B is calculated as the water-cooled wall temperature T between the starting point A and the ending point B of the monitoring range. Figure 2 As shown, in step S101 of this embodiment, the distance from the starting point A of the monitoring range of the membrane water-cooled wall of the power plant boiler to the fixed reference object is obtained by using a rangefinder. And the distance from endpoint B to the fixed reference point. Calculate the distance from the starting point A to the fixed reference object. and the distance from endpoint B to the fixed reference point The difference between them is taken as the actual measured distance between the starting point A and the ending point B. The actual measured distance Subtract the initial distance Obtain the actual thermal expansion between the starting point A and the ending point B. The initial distance This refers to the distance between the starting point A and the ending point B of the monitoring range for the membrane water-cooled wall of the power plant boiler in a non-operating environment.

[0024] As an optional implementation, in step S102 of this embodiment, the water-cooled wall temperature T is mapped to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. This refers to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range, which is mapped to the water-cooled wall temperature T according to the following formula. : ; in, and For the fitting parameters, based on the fitting parameters and The theoretical thermal expansion between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler at different water-cooled wall temperatures T can be obtained. A database is then constructed, and the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range can be obtained by querying the database using the water-cooled wall temperature T. .

[0025] Before step S102 in this embodiment, the method further includes pre-fitting to obtain fitting parameters. and : S201, Establish a heat transfer simulation model for the membrane water-cooled wall of a power plant boiler; In order to simplify the calculation of the membrane water-cooled wall of the power plant boiler, a three-dimensional model is constructed based on a single fin and imported into the simulation software as the heat transfer simulation model of the membrane water-cooled wall of the power plant boiler in this embodiment. S202, in the simulation software, the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler at different water-cooled wall temperatures T is obtained through simulation of the heat transfer simulation model. ; Figure 3 The simulated temperature distribution of the water-cooled wall tubes in this embodiment is shown below. Figure 4 This is the distribution of theoretical expansion of the water-cooled wall obtained through simulation in this embodiment; S203 represents the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of a power plant boiler at different water-cooled wall temperatures T. To fit Thus, the fitting parameters are obtained. and .

[0026] As another optional implementation, in step S102, the water-cooled wall temperature T is mapped to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. Time refers to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range, obtained by using a pre-trained machine learning model to predict the water-cooled wall temperature T. The inputs to the machine learning model include the water-cooled wall temperature T, the fin center temperature T1 at starting point A, the fin center temperature T2 at ending point B, and the material elastic modulus of the membrane water-cooled wall of the power plant boiler. and the actual measured distance between the starting point A and the ending point B The output of the machine learning model is the predicted theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. The machine learning model establishes a mapping relationship between inputs and outputs through pre-training. This machine learning model can employ a three-layer fully connected neural network model, specifically consisting of an input layer, a hidden layer, and an output layer. Its input layer includes five neurons for inputting the water-cooled wall temperature T, the fin center temperature T1 at starting point A, the fin center temperature T2 at ending point B, and the material elastic modulus of the membrane water-cooled wall in the power plant boiler. and the actual measured distance between the starting point A and the ending point B The output layer includes a single neuron node to output the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. .

[0027] In step S103 of this embodiment, the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range is used as a reference. and actual thermal expansion The functional expression for the stress in the water-cooled wall within the monitoring range is calculated as follows: ; in, The stress in the water-cooled wall within the monitoring range is expressed in Pa. This refers to the elastic modulus of the membrane water-cooled wall material in a power plant boiler, expressed in Pa. The actual measured distance between the starting point A and the ending point B of the monitoring range is used. In this embodiment, a simulation experiment was conducted on the membrane water-cooled wall of a power plant boiler. The actual measured distance between the starting point A and the ending point B of the monitoring range was used in the experiment. =0.5m, the temperature and theoretical expansion distribution of the water-cooled wall under experimental conditions were obtained through simulation as follows: Figure 5 and Figure 6 As shown, the stress of the water-cooled wall in the membrane water-cooled wall of the power plant boiler under experimental conditions can be accurately obtained by using the stress monitoring method of this embodiment.

[0028] Furthermore, as an optional implementation, this embodiment further includes the following after step S103: S301, determine whether the stress of the water-cooled wall within the monitoring range exceeds the preset threshold. If it exceeds the preset threshold, an alarm is triggered and the process exits; otherwise, proceed to step S302. S302, determine the compensation amount of the power plant boiler control parameters by referring to the table based on the water-cooled wall stress within the monitoring range; S303 sums the compensated value of the power plant boiler control parameters with the command value of the power plant boiler control parameters to obtain the compensated power plant boiler control parameters, and then issues the control parameters to control the operation of the power plant boiler. The power plant boiler control parameters can be some or all of the following: coal feed rate, fuel ratio, primary air volume, primary air velocity, secondary air volume, secondary air velocity, air supply volume, and water supply volume. The fuel ratio refers to the proportion of different grades of coal.

[0029] This embodiment also provides a stress monitoring system for a membrane water-cooled wall of a power plant boiler, including a microprocessor and a memory connected to each other, wherein the microprocessor is programmed or configured to execute the stress monitoring method for the membrane water-cooled wall of the power plant boiler.

[0030] This embodiment also provides a computer-readable storage medium storing a computer program or instructions that are programmed or configured to execute the stress monitoring method for the membrane water-cooled wall of a power plant boiler via a processor.

[0031] This embodiment also provides a computer program product, including a computer program or instructions, which are programmed or configured to execute the stress monitoring method for the membrane water-cooled wall of the power plant boiler via a processor.

[0032] Those skilled in the art will understand that the technical solutions provided by this invention may take the form of a method, system, or computer program product. Therefore, this invention may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this invention may take the form of a computer program product embodied on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, produce an implementation of the flowchart... Figure 1 One or more processes and / or boxes Figure 1The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0033] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for monitoring stress in the membrane water-cooled wall of a power plant boiler, characterized in that, Includes the following steps: S101, Obtain the water-cooled wall temperature T between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler, as well as the actual thermal expansion between the starting point A and the ending point B. ; S102 maps the water-cooled wall temperature T to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. ; S103, based on the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. and actual thermal expansion The stress in the water-cooled wall within the monitoring range was calculated.

2. The method for monitoring stress in the membrane water-cooled wall of a power plant boiler according to claim 1, characterized in that, Step S101 includes obtaining the fin center temperature T1 at the starting point A and the fin center temperature T2 at the ending point B of the monitoring range of the power plant boiler membrane water-cooled wall through thermocouples, and calculating the average value of the fin center temperature T1 at the starting point A and the fin center temperature T2 at the ending point B as the water-cooled wall temperature T between the starting point A and the ending point B of the monitoring range.

3. The method for monitoring stress in the membrane water-cooled wall of a power plant boiler according to claim 1, characterized in that, Step S101 includes obtaining the distance from the starting point A of the monitoring range of the power plant boiler membrane water-cooled wall to a fixed reference object using a rangefinder. And the distance from endpoint B to the fixed reference point. Calculate the distance from the starting point A to the fixed reference object. and the distance from endpoint B to the fixed reference point The difference between them is taken as the actual measured distance between the starting point A and the ending point B. The actual measured distance Subtract the initial distance Obtain the actual thermal expansion between the starting point A and the ending point B. The initial distance This refers to the distance between the starting point A and the ending point B of the monitoring range for the membrane water-cooled wall of the power plant boiler in a non-operating environment.

4. The method for monitoring stress in the membrane water-cooled wall of a power plant boiler according to claim 1, characterized in that, In step S102, the water-cooled wall temperature T is mapped to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. This refers to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range, which is mapped to the water-cooled wall temperature T according to the following formula. : ； in, and These are the fitting parameters.

5. The method for monitoring stress in the membrane water-cooled wall of a power plant boiler according to claim 4, characterized in that, Before step S102, the method also includes pre-fitting to obtain fitting parameters. and : S201, Establish a heat transfer simulation model for the membrane water-cooled wall of a power plant boiler; S202, in the simulation software, the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of the power plant boiler at different water-cooled wall temperatures T is obtained through simulation of the heat transfer simulation model. ; S203 represents the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range of the membrane water-cooled wall of a power plant boiler at different water-cooled wall temperatures T. To fit Thus, the fitting parameters are obtained. and .

6. The method for monitoring stress in the membrane water-cooled wall of a power plant boiler according to claim 1, characterized in that, In step S102, the water-cooled wall temperature T is mapped to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. Time refers to the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range, obtained by using a pre-trained machine learning model to predict the water-cooled wall temperature T. The inputs to the machine learning model include the water-cooled wall temperature T, the fin center temperature T1 at starting point A, the fin center temperature T2 at ending point B, and the material elastic modulus of the membrane water-cooled wall of the power plant boiler. and the actual measured distance between the starting point A and the ending point B The output of the machine learning model is the predicted theoretical thermal expansion between the starting point A and the ending point B of the monitoring range. The machine learning model establishes a mapping relationship between inputs and outputs for pre-training.

7. The method for monitoring stress in the membrane water-cooled wall of a power plant boiler according to claim 1, characterized in that, In step S103, the theoretical thermal expansion between the starting point A and the ending point B of the monitoring range is used as a basis. and actual thermal expansion The functional expression for the stress in the water-cooled wall within the monitoring range is calculated as follows: ； in, To monitor the stress in the water-cooled wall within the monitoring range, The elastic modulus of the membrane water-cooled wall material for power plant boilers. This refers to the actual measured distance between the starting point A and the ending point B of the monitoring range.

8. A stress monitoring system for a membrane water-cooled wall of a power plant boiler, comprising a microprocessor and a memory interconnected, characterized in that, The microprocessor is programmed or configured to perform the stress monitoring method for membrane water-cooled walls of power plant boilers according to any one of claims 1 to 7.

9. A computer-readable storage medium storing a computer program or instructions, characterized in that, The computer program or instructions are programmed or configured to execute, via a processor, the stress monitoring method for membrane water-cooled walls of power plant boilers as described in any one of claims 1 to 7.

10. A computer program product, comprising a computer program or instructions, characterized in that, The computer program or instructions are programmed or configured to execute, via a processor, the stress monitoring method for membrane water-cooled walls of power plant boilers as described in any one of claims 1 to 7.

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