Halogen-Free Sorbent Composition for Mercury Sequestration
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Solution Overview
Problem
Existing sorbent compositions for mercury removal in flue gas streams, such as those using halogens, face issues with corrosion, contamination of wastewater, and undesirable byproduct formation, necessitating a halogen-free solution for effective mercury sequestration.
Innovation Solution
A sorbent composition comprising a particulate sorbent, a non-halogen metal compound with a metal cation, and an inorganic sulfur-containing compound, where the sulfur has an oxidation state of equal to or less than +4, is used to capture mercury from flue gas streams, minimizing halogen content and avoiding corrosion and contamination issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If halogens are added to the sorbent composition to enhance mercury oxidation, then mercury capture efficiency is improved, but corrosion of treatment units and formation of harmful byproducts increase
Solution Approach 1:
The patent removes halogens from the sorbent composition entirely, extracting the harmful element while retaining mercury capture functionality through alternative non-halogen-based oxidation mechanisms involving metal compounds and sulfur-containing compounds
Solution Approach 2:
The patent converts the harmful effect of halogen-free operation into a benefit by using metal compounds and sulfur-containing compounds that provide oxidation capability without corrosion, turning the constraint into an advantage for environmental compliance
2Productivity
If halogens are used for mercury oxidation, then mercury sequestration is enhanced, but wastewater contamination and trihalomethane formation occur
Solution Approach 1:
The patent extracts halogens from the system completely, eliminating the source of wastewater contamination and trihalomethane formation while maintaining mercury oxidation through alternative chemical mechanisms
Solution Approach 2:
The patent introduces metal compounds and sulfur-containing compounds as intermediary substances that facilitate mercury oxidation without involving halogens, thereby preventing contamination of wastewater and formation of harmful byproducts
3Object-generated harmful factors
If halogen-free sorbent composition is used to reduce corrosion, then environmental impact is reduced, but mercury oxidation capability may be compromised
Solution Approach 1:
The patent creates a composite sorbent material combining particulate sorbent with metal compounds and sulfur-containing compounds, where the synergistic interaction of components provides both corrosion-free operation and effective mercury oxidation capability
Solution Approach 2:
The patent changes the chemical parameters of the sorbent composition by replacing halogen-based oxidation mechanisms with metal and sulfur compound-based mechanisms, altering the oxidation potential while eliminating corrosion
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 composition effectively sequesters mercury from flue gas streams without significant halogen additions, reducing corrosion risks and environmental impact, while maintaining high mercury capture efficiency.
Implementation Method 1
contact of the injected sorbent particle, such as PAC, with the mercury species, which is typically present in very dilute concentrations in the flue gas (e.g., Hg0), which is relatively inert and not easily adsorbed, into an oxidized mercury species (e.g., Hg+ and Hg+2)
Implementation Method 2
capture of the oxidized mercury species by the pores of the sorbent where it is held tightly (e.g., sequestered) without being released
Data Source
AI summary
A sorbent composition for the sequestration of mercury from a gas stream, a method for sequestering mercury from a gas stream and a method for the manufacture of a sorbent composition. The sorbent composition includes a highly porous particulate sorbent and at least two additive components, namely a non-halogen metal compound comprising a metal cation and an inorganic sulfur-containing compound, where at least a portion of the sulfur in the sulfur-containing compound has an oxidation state of equal to or less than +4. The method includes injecting the highly porous particulate sorbent and the two additive components into a gas stream, either discretely or as a single sorbent composition, to sequester mercury in the particulate sorbent. The method has a high degree of efficacy for mercury removal without requiring the addition of halogens to the gas stream.