Supercritical Unit Bypass Control for Load Rejection
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Solution Overview
Problem
The existing control systems for supercritical units during load rejection or FCB (fast load change) face challenges in accurately regulating the high-pressure bypass, leading to energy loss, potential blockages, and safety risks due to inadequate steam pressure and flow management.
Innovation Solution
A 660MW supercritical unit high-pressure bypass control system that includes a network of pipelines and valves, monitored and controlled by a controller to adjust steam flow and pressure dynamically, ensuring balanced working fluid conditions through real-time monitoring and precise valve operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the high-pressure bypass opening degree is increased to release superheated steam and maintain working fluid balance, then unit safety is improved, but energy loss increases leading to economic loss
Solution Approach 1:
The bypass valve opening degree is dynamically adjusted based on real-time monitoring of steam flow, pressure, and unit operating conditions. The control system continuously modifies the valve position to maintain optimal balance between safety requirements and energy conservation, rather than using a fixed opening degree
Solution Approach 2:
The control system implements closed-loop feedback by monitoring steam flow rate, bypass pressure, and unit operating parameters, then automatically adjusting the bypass valve opening degree to achieve the desired balance between releasing sufficient steam for safety and minimizing energy loss for economic efficiency
2Loss of energy
If the high-pressure bypass opening degree is decreased to reduce energy loss, then economic efficiency is improved, but steam flow blockage risk increases affecting unit safety
Solution Approach 1:
The bypass valve opening degree is dynamically adjusted based on real-time monitoring of steam flow, pressure, and unit operating conditions. The control system continuously modifies the valve position to maintain optimal balance between safety requirements and energy conservation, rather than using a fixed opening degree
Solution Approach 2:
The control system implements closed-loop feedback by monitoring steam flow rate, bypass pressure, and unit operating parameters, then automatically adjusting the bypass valve opening degree to achieve the desired balance between releasing sufficient steam for safety and minimizing energy loss for economic efficiency
3Speed
If the bypass valve opens rapidly to quickly release steam, then response speed is improved, but pressure fluctuations increase affecting unit stability
Solution Approach 1:
The control system employs periodic adjustment of the bypass valve opening degree in controlled stages rather than a single rapid full opening. The valve is adjusted in multiple incremental steps with monitoring intervals, allowing pressure to stabilize at each stage while still achieving timely overall response to load rejection
Solution Approach 2:
The control system anticipates pressure fluctuations by implementing predetermined control strategies and gradual valve opening sequences before full steam release is needed. This cushioning approach prevents drastic pressure swings by preparing the system in advance with controlled incremental adjustments
4Stability of the object's composition
If the bypass valve opens slowly to reduce pressure fluctuations, then pressure stability is improved, but response time increases affecting unit safety
Solution Approach 1:
The control system employs periodic adjustment of the bypass valve opening degree in controlled stages rather than a single rapid full opening. The valve is adjusted in multiple incremental steps with monitoring intervals, allowing pressure to stabilize at each stage while still achieving timely overall response to load rejection
Solution Approach 2:
The control system initiates preliminary controlled valve opening actions as soon as load rejection is detected, beginning the steam release process early with gradual adjustments. This preliminary action ensures the system starts responding immediately while maintaining stability through controlled incremental changes rather than waiting for pressure buildup
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system ensures accurate and safe steam channel switching, maintaining unit stability and safety by automatically adjusting the high-pressure bypass valve to match combustion loads, reducing drastic parameter fluctuations and maintaining fluid balance.
Implementation Method 1
the head of Pipeline 4 is connected to the inlet of a temperature and pressure reducer; the outlet of the temperature and pressure reducer is connected to the inlet of a reheater through Pipeline 3
Data Source
AI summary
A 660MW supercritical unit bypass control method after a load rejection is provided. Steam channels after the load rejection are switched without an interference, and ache steam pressure is controllable. The 660MW supercritical unit bypass control method includes Pipeline 1, Pipeline 2, Pipeline 3, and Pipeline 4; a bottom of Pipeline 3, a bottom of the Pipeline 2, and a head of the Pipeline 4 are connected by a temperature and pressure reducer; a bottom of the Pipeline 1 is connected to a head of Pipeline 2; a branch pipe is arranged between the Pipeline 1 and the Pipeline 2, and a steam turbine is arranged in the branch pipe. A high-pressure bypass control system automatically adapts to the load rejection or FCB under any loading situation, avoids drastic changes of unit parameters from loading fluctuations, meets requirements of the load rejection and the FCB.