Polydithiocarbamic Compounds for Selenium Removal and Corrosion Control
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Solution Overview
Problem
Current flue gas wet scrubber processes struggle to effectively capture selenium and minimize corrosion, leading to increased operational costs and unscheduled shutdowns due to high chloride concentrations and corrosion issues in 2205 alloy scrubbers.
Innovation Solution
The use of polydithiocarbamic compounds and polymers derived from acrylic-x and alkylamine monomers, which are added to the flue gas wet scrubber process to capture selenium and reduce oxidation-reduction potential, thereby minimizing corrosion in 2205 alloy scrubbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If 2205 alloy stainless steel is used in flue gas wet scrubbers, then cost is reduced and chloride resistance is improved, but pitting and localized corrosion increase leading to forced shutdowns
Solution Approach 1:
The patent changes the chemical parameters of the scrubber liquor by adding polydithiocarbamic compounds and other chemistries that reduce oxidation-reduction potential and control chloride concentration, creating an environment where 2205 alloy can operate reliably without sacrificing corrosion resistance
Solution Approach 2:
The patent introduces chemical intermediaries (polydithiocarbamic compounds, selenium removal chemistries) that mediate between the corrosive flue gas environment and the 2205 alloy scrubber, protecting the metal surface while allowing the use of cost-effective material
2Reliability
If PAP systems are installed to control corrosion, then corrosion rates are reduced, but device complexity and operating costs increase
Solution Approach 1:
The patent implements self-service corrosion control through chemical additives that automatically regulate the scrubber environment, eliminating the need for external PAP systems with electrodes and power supplies while maintaining corrosion protection
Solution Approach 2:
The patent replaces the mechanical/electrical PAP system with a chemical-based solution using polydithiocarbamic compounds and oxidation-reduction potential control, substituting complex equipment with simpler chemistry
3Reliability
If flue gas wet scrubbers operate at less than 2000 ppm chloride concentration, then corrosion is reduced, but water usage and operating costs increase
Solution Approach 1:
The patent changes multiple parameters simultaneously - adding polydithiocarbamic compounds, controlling oxidation-reduction potential, and managing chloride concentration dynamics - to enable high-chloride operation without corrosion, improving operating efficiency while maintaining reliability
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
These chemistries significantly reduce selenium concentrations in the aqueous phase and decrease oxidation-reduction potential, resulting in a nearly ten-fold reduction in selenium concentration and a decrease in corrosion rates, effectively addressing the challenges of selenium capture and corrosion in flue gas wet scrubber systems.
Implementation Method 1
The invention is directed toward a method for removing selenium from flue gas in a flue gas wet scrubber process... passing the flue gas into the flue gas wet scrubber process comprising a polydithiocarbamic compound of at least one polythiocarbamic material
Implementation Method 2
These chemistries significantly reduce selenium concentrations in the aqueous phase and decrease oxidation-reduction potential, resulting in a nearly ten-fold reduction in selenium concentration and a decrease in corrosion rates
Data Source
AI summary
A method and composition for the reduction of the emission of selenium into the environment from the burning of fossil fuels with the use of two chemistries, either individually or in combination with each other. The method uses polydithiocarbamic compounds, including polydithiocarbamic compounds derived from a polymer produced from acrylic-x and alkylamine in conjunction with a scrubber process to capture selenium and reduce its emission in aqueous phase blowdown. The method and composition also helps reduce corrosion in the scrubber process.