Post-Combustion Oxidant Control for Residual Gas
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Solution Overview
Problem
Existing combustion processes face challenges in achieving complete combustion in the main combustion zone, particularly when a reducing atmosphere is required, and in managing uncontrolled releases of combustible matter, which leads to residual combustible gases that cannot be accurately predicted, resulting in incomplete combustion and energy loss.
Innovation Solution
A multi-step combined combustion and post-combustion method that includes defining nominal operation modes for the post-combustion zone, monitoring combustible substances in both the flue gas and post-combusted gas, and adjusting post-combustion oxidant and fuel injection rates to ensure complete combustion of residual gases, with the option to switch between nominal and boosted post-combustion modes based on monitored thresholds and rates of change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a reducing atmosphere is maintained in the main combustion zone to avoid oxidation of charge, then oxidation protection is improved, but complete combustion of residual combustible matter cannot be achieved
Solution Approach 1:
The combustion process is divided into two distinct zones: a main combustion zone operating under reducing atmosphere for oxidation protection, and a separate post-combustion zone for complete combustion of residual gases. This spatial segmentation allows each zone to fulfill its specific function without compromise.
Solution Approach 2:
A post-combustion zone acts as an intermediary between the main combustion zone and the atmosphere, capturing and completely combusting residual combustible matter before discharge. This intermediary zone resolves the contradiction by handling the combustion function that cannot be performed in the main zone.
2Reliability
If excess oxidant is supplied to achieve complete combustion in the main combustion zone, then combustion completeness is improved, but flame temperature decreases due to dilution
Solution Approach 1:
The combustion process is separated into two zones with different oxidant supply strategies. The main combustion zone operates with controlled or limited oxidant to maintain high flame temperature, while the post-combustion zone receives excess oxidant to ensure complete combustion of residual gases without affecting the main zone temperature.
3Productivity
If monitoring and dynamic adjustment of oxidant supply is implemented, then combustion optimization is improved, but system complexity increases
Solution Approach 1:
A nominal post-combustion operation mode is defined in advance with predetermined oxidant and fuel injection rates. This preliminary configuration allows the system to operate efficiently under normal conditions without complex real-time adjustments, reducing control system complexity while maintaining combustion optimization.
Solution Approach 2:
The system can dynamically switch between nominal operation mode and boosted post-combustion mode based on monitored combustible matter levels. This dynamic adaptability optimizes combustion efficiency while keeping the control logic relatively simple through mode-based rather than continuously adjusted control.
4Reliability
If boosted post-combustion mode is activated to ensure complete combustion of residual gases, then combustion completeness is improved, but oxidant and fuel consumption increases
Solution Approach 1:
The post-combustion system operates in two modes: nominal mode for standard conditions with baseline oxidant and fuel consumption, and boosted mode for high combustible matter conditions. This dynamic operation ensures complete combustion when needed while minimizing oxidant and fuel consumption during normal operation.
Solution Approach 2:
The system monitors the amount of combustible matter in the flue gas and uses this feedback to determine when to activate boosted post-combustion mode. This feedback-based control ensures that increased oxidant and fuel consumption occurs only when necessary to achieve complete combustion, optimizing resource usage.
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 optimizes both main and post-combustion processes, ensuring complete combustion, reducing environmental emissions, and maximizing energy recovery by dynamically adjusting post-combustion conditions in response to real-time monitoring data.
Implementation Method 1
the thus supplied fuel is combusted with the supplied oxidant inside the main combustion zone, whereby heat and flue gas are produced
Implementation Method 2
residual combustible matter present in the flue gas is combusted with post-combustion oxidant
Data Source
Figure 1
AI summary
Combined combustion and post-combustion method whereby flue gas is generated by combustion in a main combustion zone 10, the flue gas 17 being evacuated from the main combustion zone 10 and introduced into a post-combustion zone 19 where the flue gas 17 is subjected to post-combustion and post-combusted gas 23 is obtained which is evacuated from the post-combustion zone 19, whereby a first level of one or more combustible substances in the flue gas 17 evacuated from the main combustion zone 10 and/or a second level of one or more combustible substances in the post-combusted gas 23 evacuated from the post-combustion zone 19 is/are monitored, whereby a control signal is generated on the basis of the monitored level(s) and whereby the post-combustion oxidant injection rate or the stoichiometric excess of post-combustion-oxidant with respect to post-combustion fuel is regulated in function of said control signal.