Segmented Gas Stream Ozone Scrubbing for NOx Removal
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Solution Overview
Problem
Existing methods for removing nitrogen oxides from gas streams, such as those from combustion processes, require high amounts of ozone, leading to economic and process challenges, particularly when only partial removal is needed, and result in secondary emissions and poor cost effectiveness.
Innovation Solution
The process involves dividing the gas stream into three portions, with ozone added to the portion corresponding to the desired nitrogen oxides removal percentage, allowing for partial oxidation of nitrogen oxides to highly soluble and reactive forms like N2O5, which can be efficiently removed in scrubbers, using a modified scrubber configuration with three chambers to optimize ozone usage and minimize residual ozone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ozone is added in stoichiometric amounts (1.5 moles per mole of NO) to achieve high nitrogen oxides removal (around 90%), then nitrogen oxides removal efficiency is improved, but ozone consumption increases leading to economic challenges
Solution Approach 1:
The gas stream is divided into three separate streams, with ozone added only to the portion corresponding to the desired nitrogen oxides removal percentage. This segmentation allows partial treatment of the gas stream, reducing total ozone consumption while maintaining effective nitrogen oxides removal in the treated portion.
Solution Approach 2:
Instead of treating the entire gas stream with stoichiometric ozone amounts to achieve 90% removal, the invention applies partial action by treating only a portion of the gas stream. This allows achieving the desired removal level in the treated portion while reducing overall ozone consumption and economic costs.
2Manufacturing precision
If ozone is added in excess stoichiometric amounts to ensure complete nitrogen oxides oxidation, then nitrogen oxides removal is improved, but secondary emissions and poor cost effectiveness occur
Solution Approach 1:
By segmenting the gas stream into three portions and adding ozone only to the treated portion, the invention avoids excessive ozone addition to the entire stream. This reduces the formation of secondary emissions while maintaining complete oxidation of nitrogen oxides in the treated portion.
Solution Approach 2:
The invention converts the potential harm of excessive ozone addition into a benefit by using ozone only where needed. The modified scrubber configuration with three chambers allows precise control of ozone addition, converting what would be harmful excess ozone into a controlled reagent that achieves complete nitrogen oxides oxidation without generating secondary emissions.
3Loss of substance
If a modified scrubber configuration with three chambers is used to optimize ozone usage, then ozone consumption is reduced, but device complexity increases
Solution Approach 1:
The scrubber is divided into three chambers corresponding to three gas streams. This segmentation allows independent control of ozone addition to each chamber, optimizing ozone consumption while providing a modular structure that manages complexity through systematic division of functions.
Solution Approach 2:
The modified scrubber configuration with three chambers serves multiple functions: it separates gas streams for differential ozone treatment, optimizes ozone consumption, and maintains sulfur oxides removal efficiency. This multi-functionality justifies the increased device complexity by delivering multiple benefits from a single integrated system.
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 reduces ozone consumption by 25% compared to prior methods, achieves efficient nitrogen oxides removal with minimal secondary emissions, and allows for staged reductions to meet regulatory requirements without compromising sulfur oxides removal efficiency.
Implementation Method 1
The chemistries and techniques are directed towards high levels of nitrogen oxides removal (around 90%) and require 1.5 moles of ozone per mole of nitrogen oxide present in the gas stream
Implementation Method 2
forming higher oxides of nitrogen, especially the pentavalent form or higher which are quite water soluble and readily removed by wet scrubbing
Data Source
Figure 1~2
Figure 3
AI summary
In a method for removing a portion of contaminants, such as nitrogen oxides, from an exhaust gas stream of a combustion process, the exhaust gas stream is separated into two or more gas streams. At least one of the two or more gas streams is treated first by mixing with ozone. The treated gas stream is then fed to a scrubber where it is recombined with the untreated gas stream. Excess ozone present in the treated gas stream is consumed by oxidation of contaminants in the untreated gas stream before the combined gas stream is released to the atmosphere. The portion of the gas stream separated for mixing with ozone directly correlates to the amount of nitrogen oxides that are desired to be removed from the stream.