Hydrated Powder Activated Carbon Mercury Capture
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Solution Overview
Problem
Emissions treatment systems using powder activated carbon (PAC) for mercury removal face inefficiencies due to PAC's hydrophilicity, which competes with lime for moisture, requiring excessive lime slurry in flue gas desulfurization systems, necessitating improved control and treatment of pollutants like mercury and sulfur dioxide.
Innovation Solution
Conditioning PAC by hydrating it to create a 1%-7% solution, which is introduced into the emissions pathway, allowing for effective mercury capture and optimizing fly ash moisture content to enhance sulfur dioxide removal, thereby reducing the need for excessive lime slurry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If PAC is used for mercury removal, then mercury capture efficiency is improved, but excessive lime slurry is required due to moisture competition
Solution Approach 1:
The patent applies parameter changes by controlling the moisture content of PAC to an optimal range of 5-15% through a hydration control system. This parameter optimization reduces PAC's hydrophilicity and moisture competition with lime slurry, thereby decreasing the quantity of lime slurry required while maintaining effective mercury capture
Solution Approach 2:
The patent implements feedback control through moisture sensors that monitor PAC moisture content and adjust hydration water addition accordingly. This closed-loop feedback system ensures PAC maintains optimal moisture levels, preventing excessive moisture competition with lime slurry and reducing the quantity of lime slurry needed
2Object-affected harmful factors
If PAC is used to adsorb mercury, then mercury removal is achieved, but PAC competes for moisture with lime reducing treatment efficiency
Solution Approach 1:
The patent changes the moisture content parameter of PAC from its naturally high hydrophilic state to an optimized 5-15% range. This parameter modification reduces PAC's moisture competition with lime, thereby improving sulfur dioxide removal efficiency while maintaining mercury removal effectiveness
Solution Approach 2:
The patent applies preliminary action by pre-hydrating and conditioning PAC before introduction to the flue gas stream. This preliminary moisture control prepares PAC to have reduced moisture competition potential, allowing both mercury adsorption and sulfur dioxide removal to proceed efficiently without interference
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
The hydration of PAC improves mercury capture and maintains optimal fly ash moisture, enhancing the efficiency of sulfur dioxide removal within the emissions treatment system, reducing operational costs and improving pollutant control.
Implementation Method 1
PAC can adsorb vaporized mercury from flue gas
Implementation Method 2
The lime slurry absorbs sulfur dioxide
Data Source
AI summary
The present technology is generally directed to systems and methods for removing mercury from emissions. More specifically, some embodiments are directed to systems and methods for removing mercury from exhaust gas in a flue gas desulfurization system. In one embodiment, a method of removing mercury from exhaust gas in a flue gas desulfurization system includes inletting the gas into a housing and conditioning an additive. In some embodiments, conditioning the additive comprises hydrating powder-activated carbon. The method further includes introducing the conditioned additive into the housing and capturing mercury from the gas.