Sulfide-Lime Sorbent for Mercury Capture in Flue Gas
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Solution Overview
Problem
Existing methods for removing mercury from flue gas in coal-fired power plants face challenges due to chemical incompatibility with lime and disposal issues, and current sorbents are not stable in acidic conditions, affecting their absorptive capacity and economic viability.
Innovation Solution
A solid state admixture of an inorganic base and a sulfide, such as ammonium, alkali metal, or transition metal sulfides, supported on materials like silicates or activated carbon, is used to capture environmental contaminants like mercury from gas streams, ensuring stability and compatibility with lime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If activated carbon is injected into the flue gas stream for mercury removal, then mercury adsorption is improved, but the activated carbon retention in fly ash waste stream adversely affects concrete performance
Solution Approach 1:
The patent uses composite materials by combining metal sulfides with lime in a specific formulation. The metal sulfide component provides mercury removal capability while the lime component ensures compatibility with concrete applications, creating a composite sorbent that achieves both pollution control and waste utilization goals
2Reliability
If supported metal sulfides are used for mercury chem-adsorption, then mercury removal efficiency is improved, but the reaction with lime destroys the absorptive capacity
Solution Approach 1:
The patent applies parameter changes by controlling the particle size, surface area, and chemical composition ratios of the metal sulfide and lime components. By optimizing these parameters, the sorbent maintains high mercury chem-adsorption efficiency while preventing the destructive reaction with lime that would otherwise eliminate the absorptive capacity
3Reliability
If conventional sorbents are used in acidic flue gas conditions, then mercury absorption is attempted, but the sorbents are not stable and lose absorptive capacity
Solution Approach 1:
The patent applies local quality by creating a sorbent formulation where different components serve specific functions: the metal sulfide provides mercury binding capability while the lime provides acid resistance. This localized functional distribution allows the sorbent to maintain stability in acidic flue gas conditions while retaining mercury absorption capability
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 solution effectively reduces mercury concentrations in flue gas streams while maintaining stability in acidic conditions and avoiding adverse effects on concrete production, thus enhancing pollution control and economic compatibility.
Implementation Method 1
The activated carbon is a high surface area material that provides for the adsorption of the mercury
Implementation Method 2
chemical species that react with mercury to chem-adsorb the elemental and oxidized mercury
Implementation Method 3
chemical species that react with mercury to chem-adsorb the elemental and oxidized mercury
Data Source
AI summary
Herein are disclosed compositions of matter, processes of manufacture and processes of use of solid state admixtures that include an inorganic base and a sulfide selected from the group consisting of an ammonium sulfide, an alkali metal sulfide, an alkali-earth metal sulfide, transition metal sulfide, and a mixture thereof. The composition can include solid state inorganic bases (e.g., calcium hydroxide and sodium sesquicarbonate) and/or gaseous bases (e.g., ammonia) and, optionally, a support material for one or more of the inorganic base and sulfide. The compositions are useful for capturing environmental contaminants, for example, from the flue gas of a coal fired power plant.