Barium Compound Sequestration for Flue Gas Desulfurization
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Solution Overview
Problem
Current methods for reducing selenium and other elements from flue gas in wet flue gas desulfurization systems are inefficient, particularly due to the challenges of controlling oxidation-reduction potential and the cycling nature of coal plant operations, which affects the precipitation of selenium species.
Innovation Solution
The introduction of barium compounds, such as barite or barium sulfide, into the flue gas desulfurization system to sequester selenium and other elements by partitioning them into a solid phase, reducing the need for ORP control and enhancing the precipitation of mercury and arsenic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reduced sulfur compounds are added to precipitate mercury from aqueous phase, then mercury removal efficiency is improved, but selenium control becomes difficult due to ORP cycling
Solution Approach 1:
The patent introduces barium sulfide as an intermediary substance that mediates between mercury precipitation and selenium control. The barium sulfide provides sulfide ions for mercury precipitation while the barium ions form insoluble barium sulfate that adsorbs selenium, thus mediating the conflicting requirements of mercury removal and selenium control without being affected by ORP cycling
Solution Approach 2:
The patent changes the chemical parameters by introducing barium sulfide instead of traditional reduced sulfur compounds. This parameter change transforms the system from one sensitive to ORP cycling to one where selenium control is achieved through barium sulfate formation and adsorption, which is not affected by oxidation-reduction potential variations
2Manufacturing precision
If ORP control is implemented to manage selenium precipitation, then selenium removal is improved, but system complexity and operational cost increase
Solution Approach 1:
The patent implements self-service by allowing barium sulfate to automatically form and adsorb selenium based on the existing chemical conditions in the scrubbing liquid. The system self-regulates selenium removal through the precipitation of barium sulfate and its subsequent adsorption of selenium, eliminating the need for external ORP control systems and complex operational interventions
Solution Approach 2:
The patent extracts the selenium control function from the ORP control system and transfers it to the barium sulfate adsorption mechanism. By taking out the dependency on ORP control, the patent simplifies the system while maintaining effective selenium removal through the inherent adsorption properties of barium sulfate
3Adaptability or versatility
If multiple chemical additives are used to control different pollutants, then pollutant removal coverage is improved, but wastewater treatment complexity increases
Solution Approach 1:
The patent applies universality by making barium sulfide a multi-functional additive that simultaneously addresses mercury precipitation, selenium adsorption, and arsenic precipitation. This single substance performs multiple pollutant control functions, replacing the need for multiple separate chemical additives and simplifying the overall wastewater treatment process
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 effectively reduces selenium and other element concentrations by 85% or more, achieving compliance with regulatory limits while minimizing the need for costly ORP control and improving the overall efficiency of wastewater treatment.
Implementation Method 1
A barium compound is then contacted with the aqueous solution under conditions such that one or more of the dissolved elements are partitioned to a solid phase
Implementation Method 2
They all share the reduced sulfur species which allows the aqueous Hg within the WFGD slurry liquid aqueous phase to react with the reduced sulfur to form the solid HgS
Data Source
AI summary
The invention pertains to methods of reducing dissolved elements such as arsenic, selenium and mercury in aqueous solutions using, for example, various barium compounds to partition said elements to a solid phase. Such methods are particularly useful for reducing such elements at various points in coal and oil-fired power plants prior to final waste water treatment.