Halogen-Modified Carbon Sorbent for Mercury Capture
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Solution Overview
Problem
Existing mercury removal technologies from flue gas, particularly those using activated carbon, are inefficient for elemental mercury capture, require large sorbent-to-mercury ratios, are costly, and generate solid waste disposal issues due to initial unreactivity and difficulty in regeneration and reuse.
Innovation Solution
A halogen/halide promoted activated carbon sorbent, specifically bromine-modified carbon, is used to enhance mercury capture efficiency, allowing for high reactivity and regeneration, with optional secondary components and alkali additives to improve reactivity and capacity, and can be prepared in-flight for immediate use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If activated carbon is used for mercury removal, then mercury capture is achieved, but sorbent reactivity is initially low requiring large sorbent-to-mercury ratios
Solution Approach 1:
The patent modifies the chemical parameters of activated carbon by incorporating halogen (chlorine, bromine, iodine) or metal oxide components, transforming it from a physically adsorbing material to one that chemically reacts with elemental mercury. This parameter change enables high reactivity at low sorbent-to-mercury ratios (≤2:1), resolving the contradiction between capture efficiency and sorbent quantity required.
Solution Approach 2:
The invention creates composite sorbent materials combining activated carbon with halogen compounds or metal oxides. These composite materials exhibit synergistic effects where the carbon provides adsorption capacity while the halogen/metal oxide components provide chemical reactivity toward elemental mercury, achieving both high efficiency and low sorbent consumption.
2Reliability
If traditional sorbents are used, then mercury removal is achieved, but regeneration and reuse are difficult causing solid waste disposal issues
Solution Approach 1:
The patent enables recovery and regeneration of the sorbent material after mercury capture. The modified activated carbon with halogen or metal oxide components can be thermally regenerated to restore its mercury-capturing capability, allowing multiple reuse cycles and converting a disposable material into a recoverable resource, thus resolving the waste disposal problem.
3Productivity
If fine carbon particles are injected into flue gas, then some mercury is removed, but contact time is very short reducing effectiveness
Solution Approach 1:
The patent changes the chemical reactivity parameter of the carbon particles by adding halogen or metal oxide components. This transformation allows the sorbent to achieve high mercury removal efficiency through rapid chemical reaction rather than relying on prolonged physical contact, effectively resolving the contradiction between removal rate and contact time.
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 halogen/halide promoted activated carbon sorbent achieves high mercury removal efficiencies with reduced sorbent requirements, lowering operational costs and enabling regeneration and reuse, thus addressing inefficiencies and waste disposal issues of traditional methods.
Implementation Method 1
highly reactive regenerable sorbents... removal of mercury from gas streams generated during the burning or gasification of fossil fuels
Implementation Method 2
In downstream process sections, such as in the ducts and stack of a combustion system, some of the elemental mercury is oxidized
Data Source
AI summary
A promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new modified carbon form containing reactive forms of halogen and halides. Optional components may be added to increase reactivity and mercury capacity. These may be added directly with the sorbent, or to the flue gas to enhance sorbent performance and/or mercury capture. Mercury removal efficiencies obtained exceed conventional methods. The sorbent can be regenerated and reused. Sorbent treatment and preparation methods are also described. New methods for in-flight preparation, introduction, and control of the active sorbent into the mercury contaminated gas stream are described.