Chlorine Dioxide Gas Scrubbing for NOx Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for removing nitrogen oxides (NOx) from gas streams are inefficient, costly, and require significant energy, making them unsuitable for industrial-scale applications, especially when dealing with high humidity and sulfur or metal-containing compounds.
Innovation Solution
A single-stage or two-stage air scrubbing method using nonionic chlorine dioxide (ClO2) to convert NOx into mineral acids and salts, with ClO2 introduced as a gas, mist, or liquid stream, and combined with an aqueous metal hydroxide solution to achieve efficient NOx removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current methods (catalytic oxidation, condensation, absorption, carbon bed adsorption) are used to remove NOx, then NOx removal is achieved, but the process becomes bulky, expensive, and maintenance intensive
Solution Approach 1:
The patent changes the chemical parameters by using a specific oxidant (chlorine dioxide or other oxidizing agents) to convert NO to NO2 in situ, altering the chemical state of the pollutant to enable more effective removal. This parameter change simplifies the overall process by eliminating the need for complex catalytic systems while maintaining high removal efficiency
Solution Approach 2:
The patent combines multiple functions into a single integrated system where oxidation and absorption occur in one process train. The oxidant is introduced directly into the gas stream to convert NO to NO2, which is then absorbed in the same or immediately following stage, merging what would traditionally require separate catalytic oxidation units and absorption beds into a unified process
2Reliability
If carbon bed adsorption is used to remove NOx, then NOx concentration is reduced, but the bed becomes saturated requiring offline cleaning or replacement
Solution Approach 1:
The patent ensures continuous operation by performing oxidation in the gas phase before absorption, converting NO to NO2 which has higher affinity for absorption media. This continuous conversion and absorption process eliminates the saturation issue that plagues pure adsorption systems, as the oxidized form is more readily and permanently captured, allowing uninterrupted operation without offline cleaning
Solution Approach 2:
By changing the chemical parameter of NOx from reduced form (NO) to oxidized form (NO2) through in-situ oxidation, the patent enhances the absorbability and retainability of the pollutant on absorption media, preventing bed saturation and eliminating the need for periodic offline cleaning or replacement
3Productivity
If wet scrubbing is used to handle high NOx concentrations, then industrial scale treatment is achieved, but multiple stages are required increasing complexity
Solution Approach 1:
The patent merges the oxidation function and absorption function into a single integrated stage or closely coupled two-stage system. By introducing oxidant into the gas stream and immediately following with absorption in the same process train, it combines what would traditionally require separate catalytic oxidation reactors and multiple absorption scrubbers into a unified system, achieving industrial scale treatment with reduced complexity
Solution Approach 2:
The patent applies preliminary oxidation of NO to NO2 before the absorption stage, converting the pollutant into a more absorbable form. This preliminary chemical transformation enables the subsequent absorption stage to handle high concentrations more effectively in a single pass or fewer stages, reducing the need for multiple sequential scrubbing stages
4Reliability
If catalytic oxidation is used to remove NOx, then NOx is converted, but the process requires specific temperature ranges and is sensitive to poisoning
Solution Approach 1:
The patent replaces the catalytic oxidation mechanism with a direct chemical oxidation approach using gaseous or vapor-phase oxidants (such as chlorine dioxide, ozone, or hydrogen peroxide). This substitution eliminates the need for catalytic materials that are sensitive to poisoning and require specific temperature ranges, allowing the oxidation to proceed under more flexible and varied operating conditions while maintaining high conversion efficiency
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 method achieves high NOx removal efficiency with lower energy consumption and operational costs, suitable for industrial-scale applications, and can handle both low and high NOx concentrations, including sulfur and metal-containing compounds, with a simplified process that reduces equipment and maintenance needs.
Implementation Method 1
A single-stage or two-stage air scrubbing method using nonionic chlorine dioxide (ClO2) to convert NOx into mineral acids and salts
Implementation Method 2
combined with an aqueous metal hydroxide solution to achieve efficient NOx removal
Data Source
AI summary
One aspect of the invention relates to a method comprising a single-stage conversion of an atmospheric pollutant, such as NO, NO2 and/or SOx in a first stream to one or more mineral acids and/or salts thereof by reacting with nonionic gas phase chlorine dioxide (ClO20 ), wherein the reaction is carried out in the gas phase. Another aspect of the invention relates to a method comprising first adjusting the atmospheric pollutant concentrations in a first stream to a molar ratio of about 1:1, and then reacting with an aqueous metal hydroxide solution (MOH). Another aspect of the invention relates to an apparatus that can be used to carry out the methods disclosed herein. The methods disclosed herein are unexpectedly efficient and cost effective, and can be applied to a stream comprising high concentration and large volume of atmospheric pollutants.