Remote Halogen Additive Injection for Mercury Removal
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Solution Overview
Problem
Current mercury control technologies, such as activated carbon injection, face limitations in effectively capturing elemental mercury at high temperatures and are costly, especially when halogen additions are required, and can interfere with the sale of fly ash and are less effective for plants using high sulfur coal or sulfur trioxide flue gas conditioning.
Innovation Solution
A method involving the addition of halogen-containing additives to feed materials at a remote location, which are then transported to an industrial facility, where they facilitate the conversion of gas-phase contaminants like mercury into forms that can be more readily captured, reducing transportation and material handling costs and enhancing mercury removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halogen addition is used to oxidize elemental mercury for capture by activated carbon, then mercury removal efficiency is improved, but transportation and material handling costs increase
Solution Approach 1:
The halogen-containing additive is incorporated into the feed material at a location remote from the industrial facility, performing the mercury control preparation in advance during material handling and transportation. This preliminary action eliminates the need for separate halogen injection systems at the facility, reducing both equipment complexity and operating costs while maintaining effective mercury removal.
Solution Approach 2:
The halogen addition function is extracted from the industrial facility's mercury control system and relocated to the feed material preparation stage. This separation allows the facility to receive pre-treated feed material that already contains the necessary halogen compounds, simplifying the facility's equipment requirements and reducing material handling complexity.
2Reliability
If activated carbon injection is used to capture mercury, then mercury control is achieved, but the plant owner cannot sell fly ash as replacement for Portland cement
Solution Approach 1:
The invention changes the chemical parameters of the feed material by incorporating halogen-containing additives that modify mercury speciation. This approach achieves mercury control through chemical transformation rather than physical adsorption by activated carbon, thereby controlling mercury emissions without contaminating fly ash with carbon that would prevent its use as cement replacement.
3Reliability
If activated carbon is used for mercury control, then some mercury capture is achieved, but effectiveness is reduced at high temperatures and with high sulfur coal
Solution Approach 1:
The invention changes the chemical environment by adding halogen-containing compounds that facilitate mercury oxidation and capture through different mechanisms than activated carbon. This chemical approach maintains effectiveness across a wider range of temperatures and coal types, including high sulfur coals, where activated carbon performance deteriorates.
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
This approach enables the removal of at least 50% of elemental and speciated mercury from gas streams, reducing equipment and operating costs at the site of end use, while being effective across various coal types and temperature conditions.
Implementation Method 1
Bromine is believed to oxidize elemental mercury and form mercuric bromide
Implementation Method 2
the treated feed material is heated at the second location to generate a gas stream
Data Source
AI summary
The present disclosure is directed to the application of additives to a feed material at a location remote from an industrial facility using the feed material.