Low-pressure cylinder cooling system after steam admission full switching of low-pressure cylinder of steam turbine

Abstract

The invention provides a low-pressure cylinder cooling system after steam admission full switching of a low-pressure cylinder of a steam turbine, and relates to the technical field of thermal engineering. The low-pressure cylinder cooling system after steam admission full switching of the low-pressure cylinder of the steam turbine comprises a cooling steam supply system, a cooling steam adjusting device, a cooling steam distribution system, a cooling steam recovery system, a monitoring and control system, a safety protection device, an auxiliary system, a thermal insulation material, an energy management system and a control system. The control system comprises a central processing unit, a predictive control algorithm module and a self-adaptive control algorithm module. By implementing a self-adaptive control algorithm and model predictive control, the response speed and efficiency of the steam turbine low-pressure cylinder cooling system can be remarkably improved, unnecessary energy consumption can be reduced, it is ensured that the system can stably operate under various conditions, and the advanced control strategies are beneficial for achieving more intelligent and more energy-saving cooling system management.

Description

Technical Field

[0001] The invention relates to the technical field of thermal engineering, and in particular to a low-pressure cylinder cooling system of a steam turbine after the steam inlet to the low-pressure cylinder is completely cut off. Background Art

[0002] A steam turbine is a device that converts the thermal energy of steam into mechanical energy. It is widely used in power generation, industrial drive, and ship propulsion. The low-pressure cylinder is a component of the steam turbine. It is responsible for handling the low-pressure part of the steam. Usually, after the steam expands through the high-pressure cylinder, it enters the low-pressure cylinder for further expansion and work. When the steam inlet to the low-pressure cylinder of the steam turbine is completely cut off, it means that the steam no longer enters the low-pressure cylinder for expansion and work. In this case, the role of the low-pressure cylinder cooling system becomes particularly important to prevent overheating and thermal stress caused by lack of steam flow. When steam no longer enters the low-pressure cylinder, the cooling system ensures that the cylinder body and internal components remain within a safe temperature range to avoid material damage or deformation caused by high temperature.

[0003] There are still some shortcomings in the use of the existing low-pressure cylinder cooling system of a steam turbine after the steam inlet to the low-pressure cylinder is completely cut off. The traditional cooling system may not be able to dynamically adjust the cooling intensity according to actual needs, resulting in insufficient cooling efficiency or excessive cooling. The traditional cooling system may lack optimization control, resulting in a large amount of energy consumption when it is not needed. When the external environmental conditions or the system status changes, the traditional cooling system may not be able to respond quickly, resulting in reduced system operation efficiency. Therefore, the technical personnel in this field provide a low-pressure cylinder cooling system after the steam inlet to the low-pressure cylinder of a steam turbine is completely cut off to solve the problems raised in the above background technology. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the deficiencies in the prior art, the present invention provides a low-pressure cylinder cooling system for a steam turbine after all steam inlet to the low-pressure cylinder is cut off, which solves the problems that the traditional cooling system may not be able to dynamically adjust the cooling intensity according to actual needs, resulting in insufficient cooling efficiency or excessive cooling; the traditional cooling system may lack optimization control, resulting in a large amount of energy consumption when it is not needed; when the external environmental conditions or system status change, the traditional cooling system may not be able to respond quickly, resulting in reduced system operating efficiency.

[0006] (II) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A low-pressure cylinder cooling system for a steam turbine after the steam inlet to the low-pressure cylinder is completely cut off, comprising:

[0008] A cooling steam supply system, the cooling steam supply system further comprising a cooling steam source and a cooling steam pipeline, the cooling steam source is from the exhaust steam of the intermediate pressure cylinder of the steam turbine or other steam sources, the cooling steam pipeline connects the cooling steam source and the low pressure cylinder to transport cooling steam;

[0009] A cooling steam regulating device, the cooling steam regulating device further comprising a regulating valve and a stop valve, the regulating valve being used to control the flow and pressure of the cooling steam to meet different cooling requirements, and the stop valve being used to cut off the supply of cooling steam when necessary;

[0010] A cooling steam distribution system, the cooling steam distribution system also includes distribution pipes and nozzles, which evenly distribute the cooling steam to various cooling areas of the low-pressure cylinder to ensure a comprehensive and uniform cooling effect;

[0011] A cooling steam recovery system, wherein the cooling steam recovery system further comprises a condenser and a steam trap. After the cooling steam releases heat in the low-pressure cylinder, it is usually condensed into water and then recovered. The steam trap is used to discharge the condensed water to prevent water hammer and corrosion;

[0012] Monitoring and control system, the monitoring and control system also retains temperature sensors, pressure sensors, humidity sensors and wind speed sensors. The temperature sensor monitors the temperature of the low-pressure cylinder and related pipelines to ensure the cooling effect. The pressure sensor monitors the pressure of the cooling steam to ensure the safe operation of the system. The humidity sensor and wind speed sensor monitor the external environmental conditions in real time.

[0013] Safety protection device, the safety protection device also includes a safety valve and an emergency shut-off valve. The safety valve automatically opens when the system pressure exceeds the design value to release the pressure and protect the system safety. The emergency shut-off valve can quickly cut off the cooling steam supply in an emergency to prevent accidents;

[0014] Auxiliary system, the auxiliary system also includes a drain system and a ventilation system, the drain system ensures that the cooling steam can be effectively discharged after condensation to avoid water accumulation, and the ventilation system helps cool or remove harmful gases;

[0015] Thermal insulation material, which insulates the cooling steam pipe and the low-pressure cylinder, reduces heat loss, and improves cooling efficiency;

[0016] Energy management system, which is used to manage energy consumption and renewable energy utilization in cooling systems. EMS can integrate solar power generation systems, energy storage systems, etc., and optimize energy use based on algorithms;

[0017] The control system includes a central processing unit, a predictive control algorithm module and an adaptive control algorithm module, which are used to run the predictive control algorithm module and the adaptive control algorithm module. The control system is responsible for processing sensor data, executing algorithms, and outputting control instructions.

[0018] Preferably, the model predicts the detailed steps of reducing energy consumption in the low-pressure cylinder cooling system of the steam turbine as follows:

[0019] S1. Establish a system model. First, a mathematical model describing the dynamic behavior of the turbine low-pressure cylinder cooling system needs to be established. This model can be based on physical principles or data-driven. The model needs to be able to describe the relationship between key variables such as cooling water flow, temperature, and pressure.

[0020] S2. Define a prediction model and use the established system model to predict the behavior of the system in the future. The prediction model is usually a discrete time model and can be expressed as:

[0021] x(k+1)=Ax(k)+Bu(k)

[0022] Where x(k) is the state of the system at time step k, u(k) is the control input, and A and B are system matrices;

[0023] S3. Set objective function and constraints. Define an objective function, which is usually to minimize energy consumption or maximize energy efficiency. The objective function may include weights of variables such as cooling water flow, pressure, and temperature. At the same time, it is necessary to set constraints on system operation, such as the upper and lower limits of cooling water flow and the temperature range.

[0024] S4. Optimize the control strategy and use the optimization algorithm to solve the objective function and find the optimal control input sequence. The optimization problem can be expressed as:

[0025]

[0026] Where U is the control input sequence, x ref is the reference trajectory, λ is the weight of the control input variable;

[0027] S5. Implement control, apply the first control input of the optimal control input sequence obtained by optimization to the system, then the system state is updated according to the actual operation situation, and repeat steps 3 and 4 to calculate the next control input;

[0028] S6. Feedback adjustment, in each control cycle, collects new system state data and adjusts the prediction model and optimization strategy based on this data to cope with model errors and external disturbances.

[0029] Preferably, the model predicts the optimization problem:

[0030] min U J

[0031] subjectto:

[0032] x min ≤x(k+i|k)≤x max

[0033] u min ≤u(k+i|k)≤u max

[0034] Among them, x min and x max is the constraint on the system state, u min and u max is the constraint that controls the input.

[0035] Preferably, the detailed steps of the adaptive control algorithm for adjusting the operation strategy of the cooling system are as follows:

[0036] A. System modeling, first of all, it is necessary to establish a mathematical model to describe the dynamic behavior of the turbine low-pressure cylinder cooling system. This model can be based on physical principles or data-driven;

[0037] B. Define control objectives and clearly define control objectives, such as keeping the cooling water temperature within a specific range or minimizing the energy consumption of the cooling system;

[0038] C. Design an adaptive controller. Design an adaptive controller that can automatically adjust control parameters according to changes in system performance and external environment. An adaptive controller usually includes a control law and a parameter adjustment mechanism.

[0039] D. Real-time monitoring and adjustment: real-time monitoring of system status and external environmental conditions, temperature, humidity and wind speed, and adjustment of control parameters based on these data;

[0040] E. Feedback adjustment: Use feedback signals to adjust control parameters according to system performance and environmental changes to ensure that the system always operates in the best state;

[0041] The implementation of the adaptive control algorithm can be based on a variety of different methods, among which adaptive gain control. The adaptive gain control algorithm automatically adjusts the gain of the controller according to the system performance. The following formula can be used to adjust the gain:

[0042]

[0043] Where K(t) is the gain at time t, K0 is the initial gain, α is the adjustment coefficient, and e(τ) is the error signal.

[0044] (III) Beneficial effects

[0045] The present invention provides a low-pressure cylinder cooling system for a steam turbine after the steam inlet to the low-pressure cylinder is completely cut off.

[0046] Beneficial effects:

[0047] 1. In the present invention, the adaptive control algorithm can dynamically adjust the operation strategy of the cooling system according to the real-time monitored system status and external environmental conditions. If an increase in ambient temperature or an increase in the temperature of the low-pressure cylinder is detected, the adaptive controller can increase the cooling water flow rate or adjust the operating frequency of the cooling water pump to adapt to the changing cooling needs.

[0048] 2. In the present invention, model predictive control can use the system model to predict future cooling needs and system behavior, so as to make adjustments in advance. Model predictive control can predict how the temperature of the low-pressure cylinder will change due to changes in ambient temperature or system load within a specific time period, and optimize the operation strategy of the cooling water pump accordingly to reduce energy consumption and keep the system within a safe temperature range.

[0049] 3. In the present invention, by implementing adaptive control algorithms and model predictive control, the response speed and efficiency of the turbine low-pressure cylinder cooling system can be significantly improved, unnecessary energy consumption can be reduced, and the system can be ensured to operate stably under various conditions. These advanced control strategies help to achieve smarter and more energy-efficient cooling system management. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the specific process of the model prediction module of the present invention;

[0051] Figure 2 It is a specific flow chart of the adaptive control algorithm module of the present invention. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Embodiment 1:

[0054] like Figure 1-2 As shown, an embodiment of the present invention provides a low-pressure cylinder cooling system for a steam turbine after the low-pressure cylinder steam inlet is completely cut off, comprising:

[0055] A cooling steam supply system, the cooling steam supply system also includes a cooling steam source and a cooling steam pipeline, the cooling steam source comes from the exhaust steam of the intermediate pressure cylinder of the steam turbine or other steam sources, the cooling steam pipeline connects the cooling steam source and the low pressure cylinder to transport cooling steam;

[0056] The cooling steam regulating device also includes a regulating valve and a stop valve. The regulating valve is used to control the flow and pressure of the cooling steam to meet different cooling requirements. The stop valve is used to cut off the supply of cooling steam when necessary.

[0057] Cooling steam distribution system, which also includes distribution pipes and nozzles, evenly distributes cooling steam to various cooling areas of the low-pressure cylinder to ensure comprehensive and uniform cooling effect;

[0058] Cooling steam recovery system, which also includes a condenser and a steam trap. After the cooling steam releases heat in the low-pressure cylinder, it is usually condensed into water and then recovered. The steam trap is used to discharge the condensed water to prevent water hammer and corrosion;

[0059] Monitoring and control system: The monitoring and control system also retains temperature sensors, pressure sensors, humidity sensors and wind speed sensors. The temperature sensor monitors the temperature of the low-pressure cylinder and related pipelines to ensure the cooling effect. The pressure sensor monitors the pressure of the cooling steam to ensure the safe operation of the system. The humidity sensor and wind speed sensor monitor the external environmental conditions in real time.

[0060] Safety protection device, which also includes safety valve and emergency shut-off valve. The safety valve automatically opens when the system pressure exceeds the design value to release the pressure and protect the system safety. The emergency shut-off valve can quickly cut off the cooling steam supply in an emergency to prevent accidents.

[0061] Auxiliary system: The auxiliary system also includes a drain system and a ventilation system. The drain system ensures that the cooling steam can be effectively discharged after condensation to avoid water accumulation. The ventilation system helps cool or remove harmful gases.

[0062] Thermal insulation materials are used to insulate the cooling steam pipes and low-pressure cylinders, reducing heat loss and improving cooling efficiency;

[0063] Energy management system, which is used to manage energy consumption and renewable energy utilization in cooling systems. EMS can integrate solar power generation systems, energy storage systems, etc., and optimize energy use based on algorithms;

[0064] Control system, the control system includes a central processing unit, a predictive control algorithm module and an adaptive control algorithm module, which are used to run the predictive control algorithm module and the adaptive control algorithm module. The control system is responsible for processing sensor data, executing algorithms, and outputting control instructions. By implementing adaptive control algorithms and model predictive control, the response speed and efficiency of the turbine low-pressure cylinder cooling system can be significantly improved, unnecessary energy consumption can be reduced, and the system can be ensured to operate stably under various conditions. These advanced control strategies help to achieve smarter and more energy-efficient cooling system management.

[0065] The model predicts the detailed steps to reduce energy consumption in the turbine low-pressure cylinder cooling system:

[0066] S1. Establish a system model. First, a mathematical model describing the dynamic behavior of the turbine low-pressure cylinder cooling system needs to be established. This model can be based on physical principles or data-driven. The model needs to be able to describe the relationship between key variables such as cooling water flow, temperature, and pressure.

[0067] S2. Define a prediction model and use the established system model to predict the behavior of the system in the future. The prediction model is usually a discrete time model and can be expressed as:

[0068] x(k+1)=Ax(k)+Bu(k)

[0069] Where x(k) is the state of the system at time step k, u(k) is the control input, and A and B are system matrices;

[0070] S3. Set objective function and constraints. Define an objective function, which is usually to minimize energy consumption or maximize energy efficiency. The objective function may include weights of variables such as cooling water flow, pressure, and temperature. At the same time, it is necessary to set constraints on system operation, such as the upper and lower limits of cooling water flow and the temperature range.

[0071] S4. Optimize the control strategy and use the optimization algorithm to solve the objective function and find the optimal control input sequence. The optimization problem can be expressed as:

[0072]

[0073] Where U is the control input sequence, x ref is the reference trajectory, λ is the weight of the control input variable;

[0074] S5. Implement control, apply the first control input of the optimal control input sequence obtained by optimization to the system, then the system state is updated according to the actual operation situation, and repeat steps 3 and 4 to calculate the next control input;

[0075] S6. Feedback adjustment, in each control cycle, collects new system state data and adjusts the prediction model and optimization strategy based on this data to cope with model errors and external disturbances.

[0076] Model prediction optimization problem:

[0077] min U J

[0078] subjectto:

[0079] x min ≤x(k+i|k)≤x max

[0080] u min ≤u(k+i|k)≤u max

[0081] Among them, x min and x max is the constraint on the system state, u min and u max It is a constraint on the control input. Model predictive control can use the system model to predict future cooling needs and system behavior, so as to make adjustments in advance. Model predictive control can predict how the temperature of the low-pressure cylinder will change due to changes in ambient temperature or system load within a specific time period, and optimize the operation strategy of the cooling water pump accordingly to reduce energy consumption and keep the system within a safe temperature range.

[0082] The detailed steps of the adaptive control algorithm to adjust the operating strategy of the cooling system are as follows:

[0083] A. System modeling, first of all, it is necessary to establish a mathematical model to describe the dynamic behavior of the turbine low-pressure cylinder cooling system. This model can be based on physical principles or data-driven;

[0084] B. Define control objectives and clearly define control objectives, such as keeping the cooling water temperature within a specific range or minimizing the energy consumption of the cooling system;

[0085] C. Design an adaptive controller. Design an adaptive controller that can automatically adjust control parameters according to changes in system performance and external environment. An adaptive controller usually includes a control law and a parameter adjustment mechanism.

[0086] D. Real-time monitoring and adjustment: real-time monitoring of system status and external environmental conditions, temperature, humidity and wind speed, and adjustment of control parameters based on these data;

[0087] E. Feedback adjustment: Use feedback signals to adjust control parameters according to system performance and environmental changes to ensure that the system always operates in the best state;

[0088] The implementation of the adaptive control algorithm can be based on a variety of different methods, among which adaptive gain control. The adaptive gain control algorithm automatically adjusts the gain of the controller according to the system performance. The following formula can be used to adjust the gain:

[0089]

[0090] Among them, K(t) is the gain at time t, K0 is the initial gain, α is the adjustment coefficient, and e(τ) is the error signal. The adaptive control algorithm can dynamically adjust the operation strategy of the cooling system according to the real-time monitored system status and external environmental conditions. If an increase in ambient temperature or a rise in low-pressure cylinder temperature is detected, the adaptive controller can increase the cooling water flow rate or adjust the operating frequency of the cooling water pump to adapt to the changing cooling demand.

[0091] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A steam turbine low-pressure cylinder cooling system after the steam inlet to the low-pressure cylinder is completely cut off, characterized in that: include: A cooling steam supply system, the cooling steam supply system further comprising a cooling steam source and a cooling steam pipeline, the cooling steam source is from the exhaust steam of the intermediate pressure cylinder of the steam turbine or other steam sources, the cooling steam pipeline connects the cooling steam source and the low pressure cylinder to transport cooling steam; A cooling steam regulating device, the cooling steam regulating device further comprising a regulating valve and a stop valve, the regulating valve being used to control the flow and pressure of the cooling steam to meet different cooling requirements, and the stop valve being used to cut off the supply of cooling steam when necessary; A cooling steam distribution system, the cooling steam distribution system also includes distribution pipes and nozzles, which evenly distribute the cooling steam to various cooling areas of the low-pressure cylinder to ensure a comprehensive and uniform cooling effect; A cooling steam recovery system, wherein the cooling steam recovery system further comprises a condenser and a steam trap. After the cooling steam releases heat in the low-pressure cylinder, it is usually condensed into water and then recovered. The steam trap is used to discharge the condensed water to prevent water hammer and corrosion; Monitoring and control system, the monitoring and control system also retains temperature sensors, pressure sensors, humidity sensors and wind speed sensors. The temperature sensor monitors the temperature of the low-pressure cylinder and related pipelines to ensure the cooling effect. The pressure sensor monitors the pressure of the cooling steam to ensure the safe operation of the system. The humidity sensor and wind speed sensor monitor the external environmental conditions in real time. Safety protection device, the safety protection device also includes a safety valve and an emergency shut-off valve. The safety valve automatically opens when the system pressure exceeds the design value to release the pressure and protect the system safety. The emergency shut-off valve can quickly cut off the cooling steam supply in an emergency to prevent accidents; Auxiliary system, the auxiliary system also includes a drain system and a ventilation system, the drain system ensures that the cooling steam can be effectively discharged after condensation to avoid water accumulation, and the ventilation system helps cool or remove harmful gases; Thermal insulation material, which insulates the cooling steam pipe and the low-pressure cylinder, reduces heat loss, and improves cooling efficiency; Energy management system, which is used to manage energy consumption and renewable energy utilization in cooling systems. EMS can integrate solar power generation systems, energy storage systems, etc., and optimize energy use based on algorithms; The control system includes a central processing unit, a predictive control algorithm module and an adaptive control algorithm module, which are used to run the predictive control algorithm module and the adaptive control algorithm module. The control system is responsible for processing sensor data, executing algorithms, and outputting control instructions.

2. A steam turbine low-pressure cylinder cooling system after full steam cut-off of low-pressure cylinder steam inlet according to claim 1, characterized in that: The model predicts the detailed steps to reduce energy consumption in the turbine low pressure cylinder cooling system as follows: S1. Establish a system model. First, a mathematical model describing the dynamic behavior of the turbine low-pressure cylinder cooling system needs to be established. This model can be based on physical principles or data-driven. The model needs to be able to describe the relationship between key variables such as cooling water flow, temperature, and pressure. S2. Define a prediction model and use the established system model to predict the behavior of the system in the future. The prediction model is usually a discrete time model and can be expressed as: x(k+1)=Ax(k)+Bu(k) Where x(k) is the state of the system at time step k, u(k) is the control input, and A and B are system matrices; S3. Set objective function and constraints. Define an objective function, which is usually to minimize energy consumption or maximize energy efficiency. The objective function may include weights of variables such as cooling water flow, pressure, and temperature. At the same time, it is necessary to set constraints on system operation, such as the upper and lower limits of cooling water flow and the temperature range. S4. Optimize the control strategy and use the optimization algorithm to solve the objective function and find the optimal control input sequence. The optimization problem can be expressed as: Where U is the control input sequence, x ref is the reference trajectory, λ is the weight of the control input variable; S5. Implement control, apply the first control input of the optimal control input sequence obtained by optimization to the system, then the system state is updated according to the actual operation situation, and repeat steps 3 and 4 to calculate the next control input; S6. Feedback adjustment, in each control cycle, collects new system state data and adjusts the prediction model and optimization strategy based on this data to cope with model errors and external disturbances.

3. A steam turbine low-pressure cylinder cooling system after full steam cut-off of low-pressure cylinder steam inlet according to claim 2, characterized in that: The model predicts the optimization problem: min U I subject to: x min ≤x(k+i|k)≤x max u min ≤u(k+i|k)≤u max Among them, x min and x max is the constraint on the system state, u min and u max is the constraint that controls the input.

4. A steam turbine low-pressure cylinder cooling system after full steam cut-off of low-pressure cylinder steam inlet according to claim 1, characterized in that: The detailed steps of the adaptive control algorithm for adjusting the operation strategy of the cooling system are as follows: A. System modeling, first of all, it is necessary to establish a mathematical model to describe the dynamic behavior of the turbine low-pressure cylinder cooling system. This model can be based on physical principles or data-driven; B. Define control objectives and clearly define control objectives, such as keeping the cooling water temperature within a specific range or minimizing the energy consumption of the cooling system; C. Design an adaptive controller. Design an adaptive controller that can automatically adjust control parameters according to changes in system performance and external environment. An adaptive controller usually includes a control law and a parameter adjustment mechanism. D. Real-time monitoring and adjustment: real-time monitoring of system status and external environmental conditions, temperature, humidity and wind speed, and adjustment of control parameters based on these data; E. Feedback adjustment: Use feedback signals to adjust control parameters according to system performance and environmental changes to ensure that the system always operates in the best state; The implementation of the adaptive control algorithm can be based on a variety of different methods, among which adaptive gain control. The adaptive gain control algorithm automatically adjusts the gain of the controller according to the system performance. The following formula can be used to adjust the gain: Where K(t) is the gain at time t, K0 is the initial gain, α is the adjustment coefficient, and e(τ) is the error signal.

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