Predictive Control System for Reducing Agent Injection in Coal Boiler Denitrification
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Solution Overview
Problem
The flow rate of exhaust gas from a boiler in thermal power plants varies, leading to inconsistent injection amounts of reducing agents, which can result in excessive use and inefficiency in denitrification processes.
Innovation Solution
A control system that predicts nitrogen oxide concentrations in exhaust gas using operation data from coal pulverizers and boilers, adjusting the injection amount of reducing agents based on predicted values to maintain target concentrations, employing machine learning models to account for variations in operation conditions and denitrification reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the injection amount of reducing agent is increased to ensure NOx concentration does not exceed regulation value, then compliance with emission regulations is improved, but excessive use of reducing agent occurs leading to inefficiency
Solution Approach 1:
The system performs preliminary prediction of NOx concentration in exhaust gas before the actual denitrification process. By using machine learning models to predict future NOx levels based on current operation data, the control system can prepare appropriate reducing agent injection amounts in advance, avoiding both excessive injection and compliance violations.
Solution Approach 2:
The control system continuously monitors operation data from coal pulverizers and boilers, compares predicted NOx concentrations with regulation values, and adjusts reducing agent injection amounts dynamically. This closed-loop feedback mechanism ensures compliance while optimizing reducing agent usage by responding to actual system conditions rather than using fixed high injection rates.
2Reliability
If the injection amount of reducing agent is set to a higher value to account for varying exhaust gas flow rates, then compliance with emission regulations is maintained, but the efficiency of reducing agent use deteriorates
Solution Approach 1:
The system transitions from static fixed injection rate control to dynamic adaptive control. The machine learning models continuously predict NOx concentrations based on real-time operation data, and the control system dynamically adjusts reducing agent injection rates accordingly. This dynamic approach maintains compliance while optimizing efficiency by matching injection rates to actual denitrification needs under varying exhaust gas flow conditions.
Solution Approach 2:
The control system changes the injection rate parameter of reducing agent based on predicted NOx concentration levels and exhaust gas flow rates. By adjusting this key parameter dynamically rather than maintaining a constant high value, the system achieves both regulatory compliance and improved efficiency in reducing agent utilization.
3Measurement precision
If machine learning models are used to predict NOx concentration and control injection amount, then precision in controlling reducing agent injection is improved, but system complexity increases
Solution Approach 1:
The system replaces complex mechanical control mechanisms with intelligent software-based machine learning models. Instead of using complicated hardware sensors and mechanical adjustment devices, the patent employs computational algorithms that process operation data to predict NOx concentrations and determine optimal injection rates, achieving high precision control through information processing rather than mechanical complexity.
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
Enables precise control of reducing agent injection, ensuring effective denitrification even with varying exhaust gas flow rates, thereby optimizing the use of reducing agents and maintaining regulatory compliance.
Implementation Method 1
The denitrification device introduces exhaust gas into a reactor including a catalyst and decomposes the nitrogen oxides in the exhaust gas into harmless nitrogen (N2) and water (H2O) by the action of the catalyst
Implementation Method 2
decomposes the nitrogen oxides in the exhaust gas into harmless nitrogen (N2) and water (H2O) by the action of the catalyst using a reducing agent (for example, ammonia (NH3))
Data Source
AI summary
A control system, for controlling an injection amount of a reducing agent injected into exhaust gas flowing from a coal-fired boiler in a thermal power generation facility toward a denitrification reactor of a denitrification device, includes: a first predictor predicting a first concentration of nitrogen oxides in the exhaust gas flowing toward the denitrification reactor based on first operation data of the thermal power generation facility; and a control device controlling the injection amount based on a predicted value of the first concentration. The first operation data includes at least either one of second operation data and third operation data, the second operation data being operation data of one or more coal pulverizers provided in the thermal power generation facility, and the third operation data being operation data of the coal-fired boiler affected by variation in operation conditions of the one or more coal pulverizers.