Sulfite Sensor Feedback for Flue Gas Desulfurization
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Solution Overview
Problem
Current aeration processes in wet flue gas desulfurization struggle to control the oxidation of sulfites in slurry tanks due to difficulties in measuring dissolved sulfite concentration, leading to inefficient energy use and excessive oxidation, which results in lost benefits and increased manganese and selenium precipitate formation.
Innovation Solution
A system and method that includes a tank with a sulfite concentration sensor and controller to adjust the oxygen flow rate based on measured sulfite levels, ensuring less than 100% oxidation, thereby maintaining dissolved sulfites to enhance sulfur dioxide absorption and prevent manganese and selenium precipitate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If more pressurized air is provided to ensure complete sulfite oxidation, then oxidation completeness is improved, but energy consumption increases and beneficial sulfites are lost
Solution Approach 1:
The patent employs a sulfite analyzer that continuously measures sulfite concentration in the slurry and provides feedback to a controller. The controller adjusts the air flow rate to the aeration system based on this feedback, maintaining sulfite levels within a target range. This closed-loop control ensures complete oxidation when needed while preventing excessive oxidation and energy waste when sulfite levels are already sufficient.
Solution Approach 2:
The system dynamically changes the air flow rate parameter based on measured sulfite concentration. When sulfite levels are high, air flow is increased to promote oxidation. When sulfite levels drop below the target range, air flow is reduced or stopped. This parameter adjustment resolves the contradiction by matching oxidation intensity to actual process needs rather than using fixed high air flow rates.
2Device complexity
If sulfite concentration is not monitored, then system complexity is reduced, but oxidation control precision deteriorates
Solution Approach 1:
The patent replaces complex manual monitoring and control mechanisms with an automated sulfite analyzer and electronic controller system. The analyzer uses chemical or optical sensing methods to automatically measure sulfite concentration, and the controller uses electronic algorithms to determine appropriate air flow adjustments. This substitution of mechanical/manual systems with automated analytical systems improves control precision while keeping the overall system manageable through standardized commercial components.
3Productivity
If excessive air is provided to the slurry, then sulfite oxidation is maximized, but manganese and selenium precipitate formation increases
Solution Approach 1:
The patent implements dynamic control of the aeration process based on real-time sulfite concentration measurements. The air flow rate is continuously adjusted to match the actual oxidation needs of the slurry. This dynamic approach prevents excessive air injection that would cause unnecessary manganese and selenium precipitate formation, while still maintaining high oxidation rates when sulfite concentrations warrant such treatment. The system adapts its oxidation intensity to process conditions rather than operating at fixed maximum capacity.
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 energy use, maintains dissolved sulfites for improved sulfur dioxide removal, reduces manganese scaling, and simplifies selenium waste treatment by favoring the selenite form, making the process more efficient and cost-effective.
Implementation Method 1
measure or estimate the dissolved sulfite concentration
Implementation Method 2
the sulfites further react with oxygen coming from aeration air bubbled into the slurry to produce sulfates
Implementation Method 3
oxygen coming from aeration air bubbled into the slurry
Implementation Method 4
Disassociation of the lime or limestone within the slurry provides calcium ions which react with the sulfates to produce gypsum
Data Source
AI summary
A system and method for controlling oxidation of sulfites in a slurry. The system includes a tank having an inlet for receiving a slurry used in wet flue gas desulfurization. The tank also includes an inlet for receiving a gas. The inlet for receiving the gas is configured so that at least a portion of the gas received in the tank is dispersed through at least a portion of the slurry received in the tank. A sensor is configured to measure a sulfite concentration S1 of the slurry received in the tank. In some embodiments, the sensor is a sulfite analyzer. In other embodiments, the sensor is a virtual analyzer. The system includes a controller. Software executing on the controller generates a signal indicative of an adjustment of a flow rate of gas into the tank based at least in part on the sulfite concentration S1.