Combustion Control via Exhaust Gas Oxygen Feedback
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Solution Overview
Problem
Conventional combustion systems lack effective control over the composition of exhaust gases, particularly oxygen levels, which is crucial for efficient carbon dioxide capture and oxy-fuel combustion processes, due to limitations in oxidant control and temperature monitoring.
Innovation Solution
The method involves introducing a fuel, oxidant, and diluent to a combustion zone, monitoring the concentrations of oxygen and carbon monoxide in the exhaust gas, and adjusting the amounts of oxidant and fuel to maintain a desired equivalence ratio, thereby controlling the composition of the exhaust gas to achieve a combined oxygen and carbon monoxide concentration of less than 2 mol%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If temperature monitoring is used to control combustion, then combustion temperature can be maintained, but control over exhaust gas composition (particularly oxygen levels) is insufficient
Solution Approach 1:
The system employs feedback control by continuously monitoring oxygen levels in the exhaust gas and adjusting the oxidant flow rate accordingly. The controller receives oxygen concentration signals and modifies the oxidant supply to maintain the desired equivalence ratio, creating a closed-loop control system that actively regulates exhaust gas composition based on real-time measurements.
Solution Approach 2:
The invention changes the control parameter from temperature monitoring to oxygen concentration monitoring. By measuring oxygen levels in the exhaust gas and using this information to adjust oxidant flow, the system transitions from temperature-based control to composition-based control, enabling precise regulation of exhaust gas parameters for improved CO2 capture efficiency.
2Quantity of substance
If inlet guide vanes are used to reduce oxidant flow at partial load, then some oxidant control is achieved, but the ability to reduce oxidant is limited and lean blow out risks increase
Solution Approach 1:
The system uses feedback control to continuously monitor oxygen concentration in the exhaust gas and adjust oxidant flow rate in real-time. This enables precise control of oxidant quantity beyond the limited range of inlet guide vanes, allowing safe operation at lower oxidant flows by maintaining optimal equivalence ratio and preventing lean blow out conditions through active regulation.
Solution Approach 2:
The invention replaces the purely mechanical inlet guide vane system with a controlled combustion system that uses electronic sensors and actuators. Instead of relying solely on mechanical flow restriction, the system uses electronic control of oxidant flow based on oxygen concentration feedback, enabling more precise and reliable oxidant quantity control at partial load conditions.
3Reliability
If more oxidant is introduced to maintain combustion stability, then combustion reliability improves, but carbon dioxide concentration in exhaust gas decreases
Solution Approach 1:
The system changes the control approach by monitoring oxygen concentration in the exhaust gas rather than relying on fixed oxidant-to-fuel ratios. This enables dynamic adjustment of the equivalence ratio to optimize both combustion stability and CO2 concentration, allowing the system to operate at higher equivalence ratios where CO2 concentration is maximized while maintaining reliability through active oxygen level control.
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 allows for precise control of exhaust gas composition, enhancing the efficiency of carbon dioxide capture and improving the operational stability of combustion systems, especially at partial load conditions and in oxy-fuel processes.
Implementation Method 1
combusting at least a portion of the fuel to produce an exhaust gas
Implementation Method 2
combusting at least a portion of the fuel to produce an exhaust gas
Implementation Method 3
The exhaust gas may be expanded to produce mechanical power
Data Source
AI summary
A fuel, an oxidant, and a diluent can be introduced to a combustion zone, wherein the oxidant comprises air, oxygen-enriched air, or oxygen-lean air. At least a portion of the fuel can be combusted to produce an exhaust gas comprising, nitrogen, nitrogen oxides, and carbon monoxide. The exhaust gas can be expanded to produce mechanical power and an expanded exhaust gas. A concentration of at least one of oxygen, hydrogen, nitrogen oxides and carbon monoxide, in the exhaust gas or the expanded exhaust gas or both can be determined, and an amount of the oxidant or the fuel introduced to the combustion zone, or both, can be adjusted based on the determined concentration to produce an exhaust gas containing a combined amount of oxygen and carbon monoxide of less than about 2 mol % and a nitrogen concentration ranging from 20 mol % to 75 mol %. The diluent to the combustion zone can include at least a portion of the exhaust gas containing a combined amount of oxygen and carbon monoxide of less than 2 mol % and a nitrogen concentration ranging from 20 mol % to 75 mol %.