Chemically-Enhanced Sorbent Activation for Mercury Removal
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Solution Overview
Problem
Current methods for removing gaseous pollutants from gas streams, particularly in coal-fired power plants, are inefficient and costly, especially for pollutants like mercury, due to the energy-intensive production of sorbents and low removal efficiency in high-sulfur coal flue gases.
Innovation Solution
Generating a chemically-enhanced activated sorbent by activating a sorbent precursor in the presence of specific chemicals, such as bromine or transition metals, to increase adsorption efficiency, and using these sorbents to convert pollutants into more easily removable forms within the gas stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrated lime or lime is produced to remove gaseous pollutants, then removal effectiveness is improved, but production energy consumption increases
Solution Approach 1:
The patent applies preliminary action by pre-impregnating the sorbent precursor with chemical agents (such as bromine, iodine, or transition metal compounds) before the activation process. This preliminary chemical treatment enhances the sorbent's effectiveness for mercury and acid gas removal, allowing lower production energies compared to producing high-purity hydrated lime or lime through energy-intensive calcination processes.
2Reliability
If activated carbon is used to remove mercury from low-sulfur coal flue gases, then removal efficiency is improved, but removal efficiency deteriorates when used for high-sulfur coal flue gases
Solution Approach 1:
The patent applies local quality by incorporating specific chemical impregnants (such as bromine, iodine, or transition metal compounds) into the activated carbon structure. These localized chemical modifications create specific binding sites that enhance mercury affinity and provide resistance to sulfur interference, allowing the sorbent to maintain high effectiveness across different coal types including high-sulfur coals.
Solution Approach 2:
The patent creates composite sorbent materials by combining activated carbon with chemical impregnants (bromine, iodine, transition metal compounds). This composite structure provides both the physical adsorption capacity of activated carbon and the chemical enhancement needed for effective mercury and acid gas removal from high-sulfur flue gases, significantly improving adaptability across different fuel types.
3Reliability
If conventional sorbents are used to remove gaseous pollutants, then removal capability is achieved, but production cost increases
Solution Approach 1:
The patent employs disposable activated carbon sorbent cartridges that are relatively inexpensive to produce and replace. These cartridges use activated carbon with chemical impregnants rather than expensive hydrated lime or lime, providing effective pollutant removal at lower cost. The cartridges are designed for easy replacement rather than regeneration, reducing operational complexity and cost.
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 chemically-enhanced activated sorbents significantly improve the removal efficiency of gaseous pollutants, including mercury, from gas streams, especially in high-sulfur coal flue gases, while reducing production costs and enhancing the sorbents' effectiveness.
Implementation Method 1
activated carbon is a sorbent used for sorption of mercury species from coal combustion flue gases
Data Source
AI summary
The invention in its various embodiments is directed to methods and equipment for generating an activated sorbent from a sorbent precursor with the addition of certain chemicals that enhance the effectiveness of the activated sorbent. The invention in its various embodiments is also directed to the methods and equipment for generating some of the chemicals that are added to the raw carbonaceous material or activated sorbent to enhance its effectiveness. The invention in its various embodiments is also directed to methods and equipment for generating certain chemicals that can be added to a gas stream to convert a given gaseous pollutant to a form that is more easily removed from the gas stream.