Halogen-Modified Activated Carbon for Mercury Capture
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Solution Overview
Problem
Existing mercury control technologies face inefficiencies in removing mercury from flue gases with low-halogen species and high sulfur concentrations, and they often compromise the usability of fly ash for concrete production due to adsorption of air entraining agents.
Innovation Solution
Development of sorbent compositions comprising powdered activated carbon with halogen-containing and alkaline components, processed to finer particle sizes for enhanced mercury capture, and inclusion of sacrificial agents to minimize foaming index impacts on fly ash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If powdered activated carbon is injected into flue gas to capture mercury, then mercury removal efficiency is improved, but the sorbent may oxidize and burn within injection lances at high temperatures
Solution Approach 1:
The patent introduces a halogen-containing component as an intermediary substance that catalyzes mercury capture while protecting the carbon sorbent from direct oxidation. The halogen component facilitates mercury adsorption at lower temperatures, reducing the thermal stress on carbon particles during injection.
Solution Approach 2:
The patent modifies the operational temperature parameter by injecting activated carbon at lower temperatures (below 500°F) rather than high temperatures. This parameter change prevents carbon oxidation and burning while maintaining effective mercury capture through the halogen-enhanced adsorption mechanism.
2Reliability
If activated carbon is used to capture mercury in low-halogen flue gases, then mercury removal is achieved, but the capture efficiency decreases when flue gas halogen concentration is low
Solution Approach 1:
The patent applies preliminary action by pre-treating the activated carbon with halogen components before injection into the flue gas. This preliminary halogenation enhances the carbon's mercury capture capability, ensuring effective operation even when the flue gas itself has low halogen concentrations.
Solution Approach 2:
The patent creates a composite sorbent material combining activated carbon with halogen-containing components. This composite structure provides both the adsorptive properties of carbon and the catalytic mercury-capturing ability of halogens, improving overall adaptability to different flue gas compositions.
3Ease of operation
If activated carbon is injected at high temperatures to ensure good distribution, then sorbent distribution is improved, but the carbon particles oxidize and burn within the injection lances
Solution Approach 1:
The halogen-containing component acts as an intermediary that enables effective sorbent distribution and mercury capture at lower temperatures. This intermediary mechanism eliminates the need for high-temperature injection, thereby preventing carbon oxidation while maintaining good sorbent distribution through alternative means.
Solution Approach 2:
The patent changes the temperature parameter from high (above 500°F) to low (below 500°F) injection conditions. This parameter change fundamentally alters the chemistry, preventing carbon oxidation while maintaining effective sorbent distribution through improved formulation and delivery methods.
4Ease of manufacture
If plain activated carbon is used in low-halogen flue gas environments, then the sorbent is simple and cost-effective, but mercury capture efficiency is poor
Solution Approach 1:
The patent develops a composite sorbent material that combines activated carbon with halogen-containing components in a cost-effective manner. This composite approach maintains the simplicity and low cost of using carbon-based materials while dramatically improving mercury capture efficiency through the synergistic halogen-carbon interaction.
Solution Approach 2:
The patent modifies the chemical composition parameters of the sorbent by incorporating halogen elements into the activated carbon structure. This parameter change transforms plain activated carbon into an enhanced composite material that maintains cost-effectiveness while achieving superior mercury capture performance.
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 sorbent compositions achieve high mercury capture efficiency in diverse flue gas environments while maintaining fly ash usability for concrete production, reducing operational costs and improving sorbent delivery efficiency.
Implementation Method 1
The injected powdered activated carbon particles capture mercury species from the flue gas
Implementation Method 2
at least one alkaline component dispersed thereon
Implementation Method 3
inclusion of sacrificial agents to minimize foaming index impacts on fly ash
Data Source
AI summary
An adsorbent composition for removing mercury from a flue gas stream, and a method of its use. The composition is a powdered activated carbon having at least one of a halogen-containing component and an alkaline component dispersed thereon. A flow agent can be composited with the material to maintain flowability in situ.