A thick-walled component stress conditioning system and method adapted for start-stop and load lift-off

Abstract

The embodiment of the present application relates to the technical field of coal-fired units, in particular to a stress regulation system and method suitable for start-stop and load change of thick-walled components. The system comprises: an induction coil arranged on the outside of the thick-walled component and forming a flow channel for the cooling medium inside; a temperature detection assembly connected with the thick-walled component for detecting the outer wall temperature and the internal working medium temperature; a cooling medium circuit for providing cooling medium into the flow channel; and a control assembly for passing alternating current into the induction coil when the thick-walled component is in the start-up stage or the load increase condition, so that the induction coil heats the outer wall of the thick-walled component; and for stopping passing alternating current into the induction coil and controlling the cooling medium circuit to flow into the electric induction cooling flow channel when the thick-walled component is in the shutdown stage or the load decrease condition, so as to cool the outer wall of the thick-walled component. The technical scheme of the present application can effectively reduce the fatigue life loss and improve the peak regulation capacity and operation flexibility of the unit within the full load range.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power unit technology, and in particular to a stress regulation system and method for thick-walled components suitable for start-up, shutdown and load adjustment. Background Technology

[0002] Currently, with the normalization of flexible operation of coal-fired power units, these units need to frequently start, stop, and change loads. During this process, the inner and outer walls of thick-walled components (such as headers and tees) will experience significant temperature differences due to inconsistent response temperatures, leading to substantial stress between the inner and outer walls. Excessive thermal stress accelerates fatigue damage to thick-walled components, seriously affecting the operational safety and service life of the unit.

[0003] In existing technologies, to control the generation of thermal stress, methods such as limiting the rate of heating, the rate of pressurization, or the rate of load reduction are commonly used to reduce stress levels. However, while this method protects thick-walled components to some extent, it significantly prolongs the start-up and shutdown time and load change response time of the unit, weakening the unit's peak-shaving capacity and flexibility.

[0004] Therefore, how to control the stress level of thick-walled components without affecting the response capability of coal-fired power units is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a stress regulation system and method for thick-walled components suitable for start-up, shutdown, and load increase / decrease, which can effectively reduce fatigue life loss and improve the peak-shaving capacity and operational flexibility of the unit.

[0006] In a first aspect, the present invention provides a stress regulation system for thick-walled components suitable for start-stop and load increase / decrease operations, comprising: An induction coil is disposed on the outside of the thick-walled component. The induction coil is a hollow conductor structure, and a flow channel for the flow of cooling medium is formed inside the conductor structure. A temperature detection component, connected to the thick-walled component, is used to detect the outer wall temperature and the internal working fluid temperature of the thick-walled component; A cooling medium circuit is connected to the flow channel inside the induction coil and is used to provide cooling medium to the flow channel; A control component, connected to the induction coil, the temperature detection component, and the cooling medium circuit, performs the following operations: Based on the outer wall temperature and the internal working fluid temperature, a predicted value for the inner wall temperature of the thick-walled component is obtained; when the thick-walled component is in the start-up phase or under increased load, and the outer wall temperature is less than the predicted inner wall temperature, an alternating current is supplied to the induction coil to heat the outer wall of the thick-walled component; when the thick-walled component is in the shutdown phase or under reduced load, and the outer wall temperature is greater than the predicted inner wall temperature, the alternating current is stopped from being supplied to the induction coil, and the cooling medium circuit is controlled to supply cooling medium into the flow channel to cool the outer wall of the thick-walled component.

[0007] In a second aspect, the present invention provides a stress regulation method for thick-walled components suitable for start-up, shutdown, and load increase / decrease, applied to the system described in the first aspect of the present invention, the method comprising: Based on the outer wall temperature and internal working fluid temperature collected by the temperature detection component, the predicted value of the inner wall temperature of the thick-walled component is obtained. When the thick-walled component is in the start-up phase or under increased load, and the outer wall temperature is lower than the predicted inner wall temperature, an alternating current is supplied to the induction coil so that the induction coil heats the outer wall of the thick-walled component. When the thick-walled component is in a shutdown or reduced-load condition, and the outer wall temperature is greater than the predicted inner wall temperature, the alternating current is stopped from being supplied to the induction coil, and the cooling medium circuit is controlled to supply cooling medium into the flow channel to cool the outer wall of the thick-walled component.

[0008] This invention provides a stress regulation system and method for thick-walled components suitable for start-up, shutdown, and load adjustment. By using the hollow structure inside the induction coil as a cooling medium channel, cooling medium is introduced into the channel during load reduction or shutdown to cool the outer wall of the thick-walled component. Conversely, the induction coil can heat the outer wall during load increase or start-up. Active heating of the outer wall during start-up or load increase by the induction coil reduces the temperature difference between the inner and outer walls, lowers the thermal stress amplitude, and allows the unit to start and increase load at a faster rate. During shutdown or load reduction, the same induction coil provides auxiliary cooling to the outer wall of the thick-walled component, reducing the reverse temperature difference and allowing the unit to shut down and reduce load at a faster rate. Continuous and active regulation of the stress state of the thick-walled component throughout start-up, shutdown, and load changes effectively reduces fatigue life loss while significantly shortening the unit's start-up and shutdown time and load change response time, improving the unit's peak-shaving capacity and operational flexibility. By using the same induction coil and cooling medium circuit, heating and cooling functions are reused, eliminating the need for additional large independent cooling devices and reducing modification costs. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of a stress regulation system for thick-walled components suitable for starting, stopping, and lifting loads, according to an embodiment of the present invention. Figure 2 It is based on Figure 1 A schematic diagram of an induction coil is shown; Figure 3 According to Figure 1 This diagram illustrates the entire process of a generator unit transitioning from a cold start-up state after shutdown to its operational state. Figure 4 According to Figure 1 The diagram illustrates a load increase process for a generating unit during operation. Figure 5 According to Figure 1 This diagram illustrates the entire process of a generator unit operating from high load to shutdown. Figure 6 According to Figure 1 The diagram illustrates a load reduction process of a generator unit during operation. Figure 7 According to Figure 1 The diagram shows a working mode under startup and load increase conditions; Figure 8 According to Figure 1 The diagram shows a working mode under shutdown and load reduction conditions.

[0011] Figure label: 1-Thick-walled components; 2-Induction coil; 3-Flow channel. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0013] Please refer to Figure 1This invention provides a stress regulation system for thick-walled components suitable for start-stop and load increase / decrease operations, comprising: The induction coil 2 is disposed on the outside of the thick-walled component 1. The induction coil 2 is a hollow conductor structure, and a flow channel 3 for the flow of cooling medium is formed inside the conductor structure. A temperature detection component is connected to the thick-walled component 1 and is used to detect the outer wall temperature and the internal working fluid temperature of the thick-walled component 1. The cooling medium circuit is connected to the flow channel 3 inside the induction coil 2 and is used to provide cooling medium to the flow channel 3. The control component, connected to the induction coil 2, the temperature detection component, and the cooling medium circuit respectively, performs the following operations: based on the outer wall temperature and the internal working medium temperature, it obtains the predicted value of the inner wall temperature of the thick-walled component 1; when the thick-walled component 1 is in the start-up stage or under increased load, and the outer wall temperature is less than the predicted value of the inner wall temperature, it supplies alternating current to the induction coil 2 to heat the outer wall of the thick-walled component 1; when the thick-walled component 1 is in the shutdown stage or under reduced load, and the outer wall temperature is greater than the predicted value of the inner wall temperature, it stops supplying alternating current to the induction coil 2 and controls the cooling medium circuit to supply cooling medium into the flow channel 3 to cool the outer wall of the thick-walled component 1.

[0014] In this embodiment of the invention, a stress regulation system for a thick-walled component 1 during start-up, shutdown, and load variation includes a thick-walled component 1, an induction coil 2 disposed on the outside of the thick-walled component 1, a temperature detection component for acquiring temperature information of the thick-walled component 1, a control component connected to the induction coil 2 and the temperature detection component, and a cooling medium circuit cooperating with the induction coil 2.

[0015] like Figure 2 As shown, the induction coil is a hollow copper tube conductor structure with an internal flow channel for the cooling medium. This channel connects to the cooling medium circuit via a cooling medium inlet and outlet. The induction coil is arranged along the outer periphery of the thick-walled component, preferably in high-stress areas, nozzle interface areas, tee pipe interface areas, or other areas with significant temperature differences between the inner and outer walls. The induction coil can employ an integral, segmented, or zoned structure. When a segmented or zoned structure is used, different coil segments can switch operating states according to the temperature conditions of different areas of the thick-walled component to adapt to the stress control requirements of localized areas.

[0016] The cooling medium circuit includes a cooling medium inlet, a cooling medium outlet, a delivery pipeline, and a flow regulation unit. The cooling medium circuit is connected to the flow channel inside the induction coil and is used to deliver the cooling medium. During startup or load increase, the cooling medium flows through the inside of the induction coil to remove the heat generated during operation, ensuring the coil operates safely. During shutdown or load reduction, the cooling medium continues to flow along its original path inside the coil. At this time, the induction coil stops energizing, and auxiliary cooling of the outer wall of the thick-walled component is achieved through heat transfer between the induction medium and the thick-walled component.

[0017] The control component regulates the on / off state, flow rate, and duration of the cooling medium circuit via a flow regulation unit. A temperature detection component is connected to the thick-walled component to acquire the outer wall temperature and internal working fluid temperature during variable load processes. The control component is connected to the induction coil, temperature detection component, and cooling medium circuit to switch and regulate the operating mode based on the temperature changes of the thick-walled component under different operating conditions. The control component obtains a predicted value for the inner wall temperature of the thick-walled component based on the outer wall temperature and internal working fluid temperature acquired by the temperature detection component. When the thick-walled component is in the start-up or load-increasing phase, and the outer wall temperature is relatively lower than the inner wall temperature, the control component controls the induction coil to be in active heating mode, applying alternating current to the induction coil to actively heat the outer wall of the thick-walled component through induction heating, thereby increasing the outer wall heating rate and reducing the temperature difference between the inner and outer walls (e.g., ...). Figure 7 (As shown). During this process, the control component adjusts the output intensity of the external adjustment unit based on the changes in the outer wall temperature, internal working fluid temperature, and temperature difference between the inner and outer walls of the thick-walled component. When the outer wall temperature reaches the preset upper limit or the temperature difference between the inner and outer walls decreases to the preset safe range, the active heating adjustment process is terminated. When the thick-walled component is in a shutdown or load reduction phase, and the outer wall temperature is relatively higher than the inner wall temperature, the control component controls the induction coil to be in an auxiliary cooling state, stops supplying alternating current to the induction coil, and controls the cooling medium circuit to supply cooling medium to the flow channel inside the induction coil. Through the heat transfer effect between the induction coil and the thick-walled component, auxiliary cooling is implemented on the outer wall to accelerate the cooling process of the outer wall and reduce the reverse temperature difference formed between the outer and inner walls (e.g., Figure 8(As shown). During this process, the control component adjusts the operating status of the cooling medium circuit. When the outer wall temperature drops to a preset range or the temperature difference between the inner and outer walls falls back to a preset safe range, the auxiliary cooling adjustment process is terminated. Throughout the start-up, shutdown, and variable load operation, the induction coils of each thick-walled component can be independently set and controlled. Different thick-walled components are adjusted by the corresponding control components according to their respective temperature status parameters, changes in the temperature difference between the inner and outer walls, and stress regulation requirements to adapt to the differentiated regulation needs of different parts. Through the same set of induction coils and cooling medium circuits, the active heating function under start-up or load increase conditions and the auxiliary cooling function under shutdown or load decrease conditions can be realized simultaneously, thereby actively regulating the stress of thick-walled components during start-up, shutdown, and variable load processes, effectively reducing the stress amplitude, while avoiding the need for additional large independent cooling devices, reducing system complexity and modification costs.

[0018] Specifically, such as Figure 3 As shown, during the initial startup phase, the inner wall temperature of the thick-walled component rises faster than the outer wall due to the rapid heating of the working fluid, while the outer wall temperature lags behind, easily generating significant temperature difference stress between the inner and outer walls. To reduce this temperature difference, the stress control system activates the induction coil before the load increases, actively heating the outer wall of the thick-walled component through induction heating, thus raising the outer wall temperature in advance, reducing the temperature difference between the inner and outer walls, and lowering the transient stress amplitude. During startup, the control components continuously monitor the temperature difference between the inner and outer walls and the outer wall temperature. When the temperature difference drops to a preset safe range or the outer wall temperature reaches the heating upper limit, heating is stopped, achieving active stress control throughout the entire load increase process.

[0019] like Figure 4 As shown, when the load increases to a higher level during operation, both the starting temperature and pressure remain at stable operating values. The inner wall temperature rises faster than the outer wall temperature, creating a localized positive temperature difference. The induction coil pre-heats the critical outer wall area, reducing the temperature difference and effectively mitigating stress fluctuations. The control components automatically adjust the heating intensity based on the temperature differences of each critical component and a preset model, controlling each coil segment in sections or zones to optimize localized temperature differences. This ensures stable stress in thick-walled components during load increases, supporting rapid load increases for the unit.

[0020] like Figure 5 As shown, when the unit gradually shuts down from high-load operation, it starts in a high-temperature and high-pressure state. The inner wall cools first, while the outer wall lags behind, easily creating a reverse temperature difference. At this time, the induction coil stops excitation heating but maintains the flow of the internal cooling medium to provide auxiliary cooling to the outer wall, accelerating the temperature drop of the outer wall and reducing the reverse temperature difference between the outer and inner walls, thereby reducing the stress amplitude during shutdown or load reduction. Through active heating and auxiliary cooling before and after shutdown or load reduction, the system achieves full-process stress control of thick-walled components, improving the safety and lifespan of the unit during start-up, shutdown, and load changes.

[0021] like Figure 6 As shown, when the unit's load drops to a lower level during operation, the starting point is a stable operating state. The inner wall temperature drops faster than the outer wall, creating a reverse temperature difference. The induction coil stops heating while maintaining the flow of cooling medium to assist in cooling the outer wall and reduce the temperature difference amplitude. The control components adjust the cooling flow rate based on the real-time temperature and the preset safety range to alleviate stress in localized high-stress areas. This ensures the structural safety of thick-walled components during rapid load reduction and supports the unit's rapid response to peak-shaving requirements.

[0022] In one embodiment of the present invention, the control component is further configured to perform the following operations: Based on the predicted inner wall temperature and outer wall temperature, the predicted inner and outer wall temperature difference is obtained; based on the predicted inner and outer wall temperature difference, the thermal state deviation of the thick-walled component is obtained; during the start-up phase or under increased load conditions, the target heating power of the induction coil is obtained based on the thermal state deviation; during the shutdown phase or under reduced load conditions, the target cooling medium flow rate and target cooling medium velocity introduced into the flow channel are obtained based on the thermal state deviation.

[0023] In this embodiment, the temperature detection component is used to acquire temperature status information of the thick-walled component during start-up, shutdown, and load changes. The temperature status information includes the outer wall temperature of the thick-walled component, the internal working fluid temperature, parameters characterizing changes in the inner wall temperature, and parameters reflecting changes in the temperature difference between the inner and outer walls. The temperature detection component can be installed at key locations on the outer wall of the thick-walled component to monitor temperature changes in the thick-walled component in real time under different operating conditions.

[0024] The control component determines the inner wall temperature or the temperature difference between the inner and outer walls of the thick-walled component based on the outer wall temperature, internal working fluid temperature, and a preset model obtained from the temperature detection component. Specifically, based on the predicted inner wall temperature and outer wall temperature, a predicted value for the temperature difference between the inner and outer walls is obtained. Based on the predicted value of the temperature difference between the inner and outer walls, the thermal state deviation of the thick-walled component is obtained. Depending on the operating stage of the thick-walled component, the corresponding control quantity is determined based on the thermal state deviation: during the start-up stage or under increased load conditions, the control component calculates the target heating power of the induction coil based on the thermal state deviation and adjusts the heating intensity of the induction coil accordingly; during the shutdown stage or under reduced load conditions, the control component calculates the target cooling medium flow rate and target cooling medium velocity introduced into the internal flow channel of the induction coil based on the thermal state deviation and adjusts the flow rate of the cooling medium circuit accordingly. Through this method, the control component adjusts the operating state, heating intensity, or cooling medium flow rate of the induction coil in real time according to the temperature change state of the thick-walled component, thereby achieving active control of the stress on the thick-walled component.

[0025] In one embodiment of the present invention, the predicted inner wall temperature is calculated using the following formula:

[0026] This is the predicted value for the inner wall temperature. The outer wall temperature, The temperature transfer coefficient between the inner and outer walls. For the internal working fluid temperature, This is the hysteresis correction factor for the temperature change on the outer wall. This is the lag correction factor for changes in the internal working fluid temperature. This is a correction factor for the temperature state evaluation quantity. It is a quantity for evaluating temperature conditions; The predicted temperature difference between the inner and outer walls is calculated using the following formula:

[0027] This is the predicted value for the temperature difference between the inner and outer walls.

[0028] In this embodiment, the current external wall temperature, internal working fluid temperature, and temperature state evaluation value are obtained. Based on the external wall temperature, the following are added: the internal and external wall temperature transfer coefficient multiplied by the difference between the internal working fluid temperature and the external wall temperature; the external wall temperature change lag correction coefficient multiplied by the rate of change of the external wall temperature; the internal working fluid temperature change lag correction coefficient multiplied by the rate of change of the internal working fluid temperature; and the temperature state evaluation value correction coefficient multiplied by the temperature state evaluation value. The result is the predicted value of the internal wall temperature. The internal and external wall temperature transfer coefficient, the external wall temperature change lag correction coefficient, the internal working fluid temperature change lag correction coefficient, and the temperature state evaluation value correction coefficient are all parameters to be predicted and are determined through iterative optimization.

[0029] After obtaining the predicted inner wall temperature, subtract the current outer wall temperature from the predicted inner wall temperature to obtain the predicted inner and outer wall temperature difference. This predicted inner and outer wall temperature difference is used to calculate the subsequent thermal state deviation, and then to determine the target heating power of the induction coil or the target cooling medium flow rate and target cooling medium velocity of the cooling medium circuit.

[0030] In one embodiment of the present invention, the thermal state deviation is calculated using the following formula:

[0031] This is the thermal state deviation. To allow for the temperature difference between the inner and outer walls, Due to the internal wall temperature limitation, A parameter characterizing the change in the predicted value of the inner wall temperature. A parameter characterizing the change in temperature difference between the inner and outer walls, , , , All are scale factors. , , , , All are weighting coefficients.

[0032] In this embodiment, the thermal state deviation includes five components: the difference between the predicted inner and outer wall temperature difference and the allowable inner and outer wall temperature difference, divided by a temperature difference scaling factor and then multiplied by a first weighting coefficient; the difference between the predicted inner wall temperature and the inner wall temperature limit, divided by an inner wall temperature scaling factor and then multiplied by a second weighting coefficient; the inner wall temperature change parameter, divided by an inner wall temperature change scaling factor and then multiplied by a third weighting coefficient; the inner and outer wall temperature difference change parameter, divided by a temperature difference change scaling factor and then multiplied by a fourth weighting coefficient; and the temperature state evaluation quantity, multiplied by a fifth weighting coefficient. The allowable inner and outer wall temperature difference and the inner wall temperature limit are preset safety thresholds. Each scaling factor is used to normalize each physical quantity, and each weighting coefficient is used to adjust the proportion of different factors in the thermal deviation.

[0033] The sum of five components yields the thermal state deviation, which characterizes the current thermal stress state of the thick-walled component. A positive thermal state deviation indicates that the outer wall temperature is relatively low, requiring active heating; a negative thermal state deviation indicates that the outer wall temperature is relatively high, requiring auxiliary cooling. Thick-walled components undergo unsteady heat transfer during start-up, shutdown, and load changes. The magnitude of the temperature difference between the inner and outer walls, the absolute level of the inner wall temperature, the rate of change of the inner wall temperature, and the rate of change of the temperature difference between the inner and outer walls all affect the thermal stress state of the thick-walled component. If the adjustment amount is determined solely based on the instantaneous temperature difference between the inner and outer walls, it is difficult to reflect the temperature change trend and the influence of thermal inertia, easily leading to adjustment lag or over-adjustment. However, the thermal state deviation constructed using five components in this embodiment of the invention more accurately, timely, and stably reflects the true thermal stress risk of the thick-walled component.

[0034] In one embodiment of the present invention, the target heating power is calculated using the following formula.

[0035] For the target heating power, As the reference heating power, For maximum allowable heating power, , , For adjustment coefficients, This is the heating deviation. , The integral term represents the time from a historical moment. up to the current moment Heating deviation Accumulated over time.

[0036] In this embodiment, the heating deviation is calculated based on the thermal state deviation. When the thermal state deviation is positive, the heating deviation is equal to the thermal state deviation; when the thermal state deviation is zero or negative, the heating deviation is zero. The target heating power consists of a reference heating power, a proportional term, an integral term, and a differential term. The proportional term is equal to the product of the proportional coefficient and the heating deviation at the current moment; the integral term is equal to the product of the integral coefficient and the integral term; and the differential term is the product of the differential coefficient and the rate of change of the heating deviation at the current moment. If the sum of the reference heating power, the proportional term, the integral term, and the differential term is less than or equal to the maximum allowable heating power, the result is directly used as the target heating power. If the sum is greater than the maximum allowable heating power, the maximum heating power is used as the target heating power. The control component, based on the calculated target heating power, applies an alternating current of corresponding power to the induction coil to actively heat the outer wall of the thick-walled component, thereby reducing the temperature difference between the inner and outer walls and lowering the thermal stress amplitude.

[0037] In one embodiment of the present invention, the target cooling medium flow rate is calculated using the following formula.

[0038] For the target cooling medium flow rate, Based on the cooling medium flow rate, For the maximum allowable cooling medium flow rate, , , For adjustment coefficients, This is the cooling deviation. , The integral term represents the time from a historical moment. up to the current moment Cooling deviation Accumulation over time; The target cooling medium flow rate is calculated using the following formula:

[0039] For the target cooling medium flow rate, This represents the cross-sectional area of ​​the flow channel.

[0040] In this embodiment, the cooling deviation is calculated based on the thermal state deviation. When the thermal state deviation is negative, the cooling deviation is equal to the absolute value of the thermal state deviation; when the thermal state deviation is zero or positive, the cooling deviation is zero. The target cooling medium flow rate consists of a reference cooling medium flow rate, a proportional term, an integral term, and a differential term. The proportional term is equal to the product of the proportional coefficient and the cooling deviation at the current moment; the integral term is equal to the product of the integral coefficient and the integral term; and the differential term is equal to the product of the differential coefficient and the rate of change of the cooling deviation at the current moment. If the sum of the reference cooling medium flow rate, the proportional term, the integral term, and the differential term is less than or equal to the maximum allowable cooling medium flow rate, the sum is used as the target cooling medium flow rate; if it is greater than the maximum allowable cooling medium flow rate, the maximum allowable cooling medium flow rate is used as the target cooling medium flow rate. After obtaining the target cooling medium flow rate, the target cooling medium flow rate is divided by the cross-sectional area of ​​the flow channel to obtain the target cooling medium velocity.

[0041] In one embodiment of the present invention, the temperature state evaluation quantity is calculated using the following formula:

[0042] For evaluating temperature conditions, The outer wall temperature, For the internal working fluid temperature, A parameter characterizing the change in the predicted value of the inner wall temperature. A parameter characterizing the change in temperature difference between the inner and outer walls; , , , This is a preset reference value. , , , As a preset scale factor, , , , These are preset weighting coefficients.

[0043] In this embodiment, the temperature state evaluation quantity is used to characterize the overall thermal state of the thick-walled component. In the formula, the outer wall temperature and the internal working fluid temperature are collected in real time by the temperature detection component. The inner wall temperature change parameter is used to characterize the change in the predicted value of the inner wall temperature, and the inner and outer wall temperature difference change parameter is used to characterize the change in the predicted value of the inner and outer wall temperature difference. Each reference value is a preset baseline value, each scale factor is used to normalize each physical quantity, and each coefficient is used to adjust the proportion of different factors in the temperature state evaluation quantity. The introduction of this temperature state evaluation quantity enables the control component to not only adjust based on the current inner and outer wall temperature difference, but also to simultaneously consider the outer wall temperature level, the internal working fluid temperature level, the inner wall temperature change trend, and the inner and outer wall temperature difference change trend. Therefore, the control component can distinguish between various operating conditions such as "same temperature difference but different temperature levels," "same temperature difference but different change trends," and "same outer wall temperature but different internal working fluid temperature changes," thereby avoiding misjudgments caused by fixed-proportion control.

[0044] In one embodiment of the present invention, the control component is further configured to perform the following operations: Construct an objective function to characterize the error between the predicted inner wall temperature and the corresponding reference value, as well as the error between the predicted inner and outer wall temperature difference and the corresponding reference value. The parameters to be predicted in the objective function are updated iteratively. When the convergence condition is met, the optimized parameters to be predicted are output. The parameters to be predicted are used to calculate the predicted value of the inner wall temperature. The convergence condition is that the change in the parameters to be predicted is less than a preset threshold. The objective function is expressed by the following formula:

[0045] Let be the objective function. The outer wall temperature, For the first The next iteration is based on the predicted outer wall temperature obtained from the parameters to be predicted. For the first The predicted inner wall temperature obtained from the second iteration. This is a reference value for the predicted inner wall temperature. For the first The predicted temperature difference between the inner and outer walls obtained from the second iteration. This serves as a reference value for the predicted temperature difference between the inner and outer walls. The parameters to be predicted are: , The temperature transfer coefficient between the inner and outer walls. This is the hysteresis correction factor for the temperature change on the outer wall. This is the lag correction factor for changes in the internal working fluid temperature. This is a correction factor for the temperature state evaluation quantity. For the preset time window, and These are the weighting coefficients; Update the parameters to be predicted as follows:

[0046] For the first The parameters to be predicted in the (m+1)th step of the next iteration. For the first The parameters to be predicted in the m-th step of the iteration. For the first The learning step size in the m-th step of the nth iteration. For the objective function in the current parameters The gradient at that point.

[0047] In this embodiment, the parameters to be predicted in the formula for calculating the predicted inner wall temperature are determined by constructing an objective function and iteratively optimizing it. These parameters include: the temperature transfer coefficient between the inner and outer walls, the lag correction coefficient for the outer wall temperature change, the lag correction coefficient for the internal working fluid temperature change, and the correction coefficient for the temperature state evaluation quantity. The objective function includes three errors: the square of the difference between the measured outer wall temperature and the predicted outer wall temperature calculated based on the current parameters, summed over all times within the time window; the weighting coefficient multiplied by the square of the difference between the predicted inner wall temperature and the reference predicted inner wall temperature; and the weighting coefficient multiplied by the square of the difference between the predicted inner and outer wall temperature difference and the reference predicted inner and outer wall temperature difference. Gradient descent is used for parameter updates: the next predicted parameter is equal to the predicted parameter of the current step minus the learning step size multiplied by the gradient of the objective function at the current parameter. After each update, the objective function value is recalculated, and it is determined whether the change in the predicted parameter is less than a preset threshold. When the change in the predicted parameter is less than the preset threshold, the convergence condition is considered met, iteration stops, and the currently optimized predicted parameter is output.

[0048] In one embodiment of the present invention, an insulating and heat-conducting layer is provided between the outer wall of the thick-walled component and the induction coil.

[0049] In this embodiment, an insulating and thermally conductive layer is provided between the outer wall of the thick-walled component and the induction coil. This insulating and thermally conductive layer is made of a high-temperature resistant insulating and thermally conductive material, specifically an insulating and thermally conductive coating, an insulating and thermally conductive thin pad, or an insulating and thermally conductive composite layer structure. The insulating and thermally conductive layer is a thin layer structure with a thickness of 0.05 to 2 mm. The insulating and thermally conductive layer can be continuously disposed in the contact area corresponding to the induction coil and the thick-walled component, or it can be locally disposed in key areas where the distance between the induction coil and the thick-walled component is small and the insulation requirements are high. This insulating and thermally conductive layer is used to form an interface layer between the induction coil and the thick-walled component that has both insulating and thermally conductive properties. It can prevent electrical short circuits or partial discharges between the induction coil and the thick-walled component, ensuring the electrical insulation safety between them; and reduce the thermal resistance caused by excessive air gaps, maintaining effective heat transfer between the induction coil and the thick-walled component. By providing the insulating and thermally conductive layer, this system can achieve efficient heat exchange between the induction coil and the thick-walled component while ensuring electrical safety, thereby supporting the smooth implementation of active heating and auxiliary cooling functions.

[0050] This invention discloses a stress regulation method for thick-walled components suitable for start-stop and load increase / decrease operations. The method is applied to a stress regulation system for thick-walled components suitable for start-stop and load increase / decrease operations, and includes the following steps: Based on the outer wall temperature and internal working fluid temperature collected by the temperature detection component, the predicted value of the inner wall temperature of the thick-walled component is obtained. When the thick-walled component is in the start-up phase or under increased load, and the outer wall temperature is lower than the predicted inner wall temperature, an alternating current is supplied to the induction coil so that the induction coil heats the outer wall of the thick-walled component. When the thick-walled component is in a shutdown or reduced-load condition, and the outer wall temperature is greater than the predicted inner wall temperature, the alternating current is stopped from being supplied to the induction coil, and the cooling medium circuit is controlled to supply cooling medium into the flow channel to cool the outer wall of the thick-walled component.

[0051] It is understood that the method embodiments and system embodiments provided by the present invention are based on the same inventive concept and have the same beneficial effects. The beneficial effects of the method embodiments will not be elaborated here.

[0052] In summary, this invention provides a stress regulation system and method for thick-walled components suitable for start-up, shutdown, and load adjustment. By using the hollow structure inside the induction coil as a channel for the cooling medium, cooling medium is introduced into the channel during load reduction or shutdown to cool the outer wall of the thick-walled component. Additionally, the induction coil can heat the outer wall during load increase or start-up. Active heating of the outer wall of the thick-walled component during start-up or load increase by the induction coil reduces the temperature difference between the inner and outer walls, lowers the thermal stress amplitude, and allows the unit to start up and increase load at a faster rate. During shutdown or load reduction, the same induction coil is used for auxiliary cooling of the outer wall of the thick-walled component, reducing the reverse temperature difference and allowing the unit to shut down and reduce load at a faster rate. Continuous and active regulation of the stress state of the thick-walled component throughout the start-up, shutdown, and load change processes effectively reduces fatigue life loss while significantly shortening the start-up and shutdown time and load change response time of the unit, thus improving the unit's peak-shaving capacity and operational flexibility. By using the same set of induction coils and cooling medium circuits, the heating and cooling functions can be reused, eliminating the need for additional large independent cooling devices and reducing the cost of modification.

[0053] By constructing prediction models for inner wall temperature and the temperature difference between inner and outer walls, accurate prediction of the inner wall temperature, which is difficult to measure directly, was achieved, providing a reliable data foundation for stress regulation. Based on this, a thermal state deviation quantity containing multiple components was constructed to comprehensively evaluate the thermal stress state of thick-walled components. Heating and cooling deviation quantities were established separately, enabling independent adjustment of heating and cooling control and avoiding mutual interference during the control process. Simultaneously, a proportional-integral-derivative control method was used to calculate the target heating power and target cooling medium flow rate, ensuring the stability and safety of the control process.

[0054] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0055] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A stress regulation system for thick-walled components suitable for start-stop and load adjustment, characterized in that, include: An induction coil is disposed on the outside of the thick-walled component. The induction coil is a hollow conductor structure, and a flow channel for the flow of cooling medium is formed inside the conductor structure. A temperature detection component, connected to the thick-walled component, is used to detect the outer wall temperature and the internal working fluid temperature of the thick-walled component; A cooling medium circuit is connected to the flow channel inside the induction coil and is used to provide cooling medium to the flow channel; A control component, connected to the induction coil, the temperature detection component, and the cooling medium circuit, performs the following operations: Based on the outer wall temperature and the internal working fluid temperature, a predicted value for the inner wall temperature of the thick-walled component is obtained; when the thick-walled component is in the start-up phase or under increased load, and the outer wall temperature is less than the predicted inner wall temperature, an alternating current is supplied to the induction coil to heat the outer wall of the thick-walled component; when the thick-walled component is in the shutdown phase or under reduced load, and the outer wall temperature is greater than the predicted inner wall temperature, the alternating current is stopped from being supplied to the induction coil, and the cooling medium circuit is controlled to supply cooling medium into the flow channel to cool the outer wall of the thick-walled component. The control component is also used to perform the following operations: Based on the predicted inner wall temperature and outer wall temperature, the predicted inner and outer wall temperature difference is obtained; based on the predicted inner and outer wall temperature difference, the thermal state deviation of the thick-walled component is obtained; during the start-up phase or under increased load conditions, the target heating power of the induction coil is obtained based on the thermal state deviation; during the shutdown phase or under reduced load conditions, the target cooling medium flow rate and target cooling medium velocity introduced into the flow channel are obtained based on the thermal state deviation. The predicted inner wall temperature is calculated using the following formula: This is the predicted value for the inner wall temperature. The outer wall temperature, The temperature transfer coefficient between the inner and outer walls. For the internal working fluid temperature, This is the hysteresis correction factor for the temperature change on the outer wall. This is the lag correction factor for changes in the internal working fluid temperature. This is a correction factor for the temperature state evaluation quantity. It is a quantity for evaluating temperature conditions; The predicted temperature difference between the inner and outer walls is calculated using the following formula: This is the predicted value for the temperature difference between the inner and outer walls; The thermal state deviation is calculated using the following formula: This is the thermal state deviation. To allow for the temperature difference between the inner and outer walls, Due to the internal wall temperature limitation, A parameter characterizing the change in the predicted value of the inner wall temperature. A parameter characterizing the change in temperature difference between the inner and outer walls, , , , All are scale factors. , , , , All are weighting coefficients.

2. The system according to claim 1, characterized in that, The target heating power is calculated using the following formula. For the target heating power, As the reference heating power, For maximum allowable heating power, , , For adjustment coefficients, This is the heating deviation. , The integral term represents the time from a historical moment. up to the current moment Heating deviation Accumulated over time.

3. The system according to claim 1, characterized in that, The target cooling medium flow rate is calculated using the following formula. For the target cooling medium flow rate, Based on the cooling medium flow rate, For the maximum allowable cooling medium flow rate, , , For adjustment coefficients, This is the cooling deviation. , The integral term represents the time from a historical moment. up to the current moment Cooling deviation Accumulation over time; The target cooling medium flow rate is calculated using the following formula: For the target cooling medium flow rate, This represents the cross-sectional area of ​​the flow channel.

4. The system according to claim 3, characterized in that, The temperature state evaluation quantity is calculated using the following formula: For evaluating temperature conditions, The outer wall temperature, For the internal working fluid temperature, A parameter characterizing the change in the predicted value of the inner wall temperature. A parameter characterizing the change in temperature difference between the inner and outer walls; , , , As a preset reference value, , , , As a preset scale factor, , , , These are preset weighting coefficients.

5. The system according to claim 1, characterized in that, The control component is also used to perform the following operations: Construct an objective function, which is used to characterize the error between the predicted value of the inner wall temperature and the corresponding reference value, and between the predicted value of the temperature difference between the inner and outer walls and the corresponding reference value; The parameters to be predicted in the objective function are updated iteratively. When the convergence condition is met, the optimized parameters to be predicted are output. The parameters to be predicted are used to calculate the predicted value of the inner wall temperature. The convergence condition is that the change in the parameters to be predicted is less than a preset threshold. The objective function is expressed by the following formula: Let be the objective function. The outer wall temperature, For the first k The next iteration is based on the predicted outer wall temperature obtained from the parameters to be predicted. For the first k The predicted inner wall temperature obtained from the second iteration. This is a reference value for the predicted inner wall temperature. For the first k The predicted temperature difference between the inner and outer walls obtained from the second iteration. This serves as a reference value for the predicted temperature difference between the inner and outer walls. The parameters to be predicted are: , The temperature transfer coefficient between the inner and outer walls. This is the hysteresis correction factor for the temperature change on the outer wall. This is the lag correction factor for changes in the internal working fluid temperature. This is a correction factor for the temperature state evaluation quantity. For the preset time window, and These are the weighting coefficients; The parameters to be predicted are updated as follows: Let be the parameters to be predicted in the (m+1)th step of the k-th iteration. Let m be the parameter to be predicted in the k-th iteration. Let m be the learning step size in the k-th iteration. For the objective function in the current parameters The gradient at that point.

6. The system according to claim 1, characterized in that, Also includes: An insulating and heat-conducting layer is provided between the outer wall of the thick-walled component and the induction coil.

7. A stress regulation method for thick-walled components suitable for start-up, shutdown, and load increase / decrease, characterized in that, Applied to the system according to any one of claims 1-6, the method comprises: Based on the outer wall temperature and internal working fluid temperature collected by the temperature detection component, the predicted value of the inner wall temperature of the thick-walled component is obtained. When the thick-walled component is in the start-up phase or under increased load, and the outer wall temperature is lower than the predicted inner wall temperature, an alternating current is supplied to the induction coil so that the induction coil heats the outer wall of the thick-walled component. When the thick-walled component is in a shutdown or reduced-load condition, and the outer wall temperature is greater than the predicted inner wall temperature, the alternating current is stopped from being supplied to the induction coil, and the cooling medium circuit is controlled to supply cooling medium into the flow channel to cool the outer wall of the thick-walled component.

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