Boiler Exergy Feed-Forward Coal Control During Load Transients
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Solution Overview
Problem
Coal-fired power plants face challenges in maintaining operational flexibility, safety, and economy during transient load-varying processes due to non-linearity, inertia, and time-delay in boiler systems, leading to over-temperature issues and inefficient heat storage and release.
Innovation Solution
A method that uses exergy storage variation as a feed-forward signal to dynamically control coal supply quantity in the boiler system, correcting the coal supply based on real-time and steady-state exergy storage amounts to improve thermodynamic device stability and parameter quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the stored heat of the boiler system is released during transient load-varying process, then the operational flexibility is improved, but over-temperature of metal heating surface occurs causing safety issues
Solution Approach 1:
The invention calculates the exergy storage variation in advance during transient load-varying processes and uses it as a feed-forward signal to adjust coal supply quantity before over-temperature occurs. This preliminary action prevents safety issues while maintaining operational flexibility by proactively managing heat storage and release.
2Quantity of substance
If excess coal quantity is supplied during transient load-varying process, then the heat storage is improved, but the economy deteriorates due to poor energy efficiency
Solution Approach 1:
The invention implements a feedback mechanism by calculating exergy storage variation and using it to dynamically adjust coal supply quantity. This ensures optimal heat storage is maintained while avoiding excess coal supply that would waste energy and reduce economy during transient load-varying processes.
3Manufacturing precision
If the heat of the boiler system is stored during transient load-varying process, then the parameter quality is improved, but the economy deteriorates due to excess coal quantity
Solution Approach 1:
The invention calculates exergy storage variation in advance and uses it as a feed-forward signal to adjust coal supply quantity before transient processes begin. This preliminary action ensures parameter quality is maintained while avoiding excess coal supply that would waste energy and reduce economy.
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
This approach enhances the economic and safety performance of coal-fired units by effectively managing thermal inertia and time delays, ensuring high-quality steam parameters and flexible energy conversion.
Implementation Method 1
obtaining an exergy storage amount of each thermodynamic device of the boiler system... calculating a total exergy storage amount Exi of the ith boiler superheater... the total exergy storage amount Exi comprises an exergy storage amount of the working fluid and an exergy storage amount of the metal heating surface
Data Source
AI summary
A method for controlling a coal supply quantity during a transient load-varying process considering exergy storage correction of a boiler system of a coal-fired unit is provided. Temperatures and pressures of working fluid and metal heating surface of the boiler system of the coal-fired unit are measured and recorded in real-time, and converted into the exergy storage amount at different operating load points. During the transient operation process, the real-time exergy storage amount of the boiler system is compared with the exergy storage amount at the corresponding steady-state load point, and the real-time exergy storage variation is obtained; thereafter, the feed-forward control signal of coal supply quantity input is superposed to the existing coal supply quantity command of the boiler system, and the coal supply quantity signal of the boiler system based on the exergy storage correction is finally generated.