Combustion Control Logic for Waste Gas Flow and NOx Stability
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Solution Overview
Problem
Existing combustion control systems fail to account for variations in waste gas flow, leading to temperature jumps and increased nitrogen oxide emissions, particularly when operating under stoichiometric conditions.
Innovation Solution
A method and control logic that measures waste stream flow, predicts temperature changes, adjusts the air-to-fuel ratio to maintain constant temperature, and optionally operates sub-stoichiometrically to minimize nitrogen oxide formation, using a flowmeter, temperature controller, feed forward block, and extremum-seeking controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If stoichiometric combustion conditions are used to maximize efficiency, then energy efficiency is improved, but nitrogen oxide emissions increase and temperature control becomes unstable
Solution Approach 1:
The system dynamically changes the air-to-fuel ratio parameter based on real-time waste gas flow measurements. When waste gas flow increases, the system transitions from stoichiometric to sub-stoichiometric conditions by reducing air supply relative to fuel, thereby controlling nitrogen oxide emissions while maintaining combustion efficiency. This parameter adjustment resolves the contradiction between efficiency and emissions.
Solution Approach 2:
The control system performs preliminary measurement of waste gas flow and predicts temperature changes before they occur. By anticipating the effects of flow variations, the system proactively adjusts air and fuel supply ratios to prevent nitrogen oxide formation and temperature instability, rather than reacting after the problem occurs.
2Adaptability or versatility
If waste gas flow varies rapidly, then process flexibility is improved, but temperature stability deteriorates causing trips and loss of authorization
Solution Approach 1:
The system implements continuous feedback by measuring waste gas flow with flowmeters and using this information to dynamically adjust air and fuel supply. The temperature indicators provide feedback on combustion stability, allowing the control system to make real-time adjustments that maintain temperature stability despite rapid variations in waste gas flow, preventing trips and loss of authorization.
Solution Approach 2:
The control system transitions from static combustion conditions to dynamic adjustment of air-to-fuel ratios. The system continuously adapts the combustion parameters based on real-time waste gas flow measurements, enabling it to handle rapid flow variations while maintaining stable combustion temperatures through dynamic balance of oxidizer and fuel supply.
3Object-generated harmful factors
If sub-stoichiometric operation is used to minimize nitrogen oxides, then emissions are reduced, but combustion efficiency decreases and operating load is reduced
Solution Approach 1:
The system performs preliminary measurement and prediction of temperature changes based on waste gas flow variations. By anticipating the need for sub-stoichiometric operation before nitrogen oxides form, the system can transition to sub-stoichiometric conditions more efficiently, minimizing the impact on operating load and productivity while still achieving emission reduction goals.
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 quick response to flow changes, reduces temperature spikes, minimizes nitrogen oxide emissions, and operates efficiently at lower loads, ensuring safe and environmentally responsible combustion.
Implementation Method 1
measuring the flow of a waste stream comprising a compound with calorific value
Implementation Method 2
predicting if the flow measured leads to a temperature change in the combustion of the stream
Implementation Method 3
Combustion can be described as the rapid oxidation of combustible, such as fuel, resulting in the release of usable heat
Data Source
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AI summary
The present invention relates to a method for controlling a thermal combustion system and a control logic for a combustion system.