Nitrogen Oxide Removal via Partial Ozone Oxidation
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Solution Overview
Problem
Current methods for removing nitrogen oxides from sulfuric acid production processes are inefficient, particularly due to high ozone requirements and the formation of undesirable nitrate byproducts, which are costly and environmentally challenging, especially when ozone is introduced in high concentrations in hot sulfur dioxide streams.
Innovation Solution
Partial oxidation of nitrogen oxides by ozone in sub-stoichiometric quantities, followed by absorption of nitrous acid in a neutral or acidic medium with urea or ammonia, which decomposes to nitrogen, carbon dioxide, and water, reducing ozone usage and minimizing nitrate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high concentrations of ozone are introduced to remove nitrogen oxides from sulfuric acid production processes, then nitrogen oxide removal efficiency is improved, but ozone consumption increases and nitrate byproduct formation increases
Solution Approach 1:
The patent applies partial action by introducing ozone in sub-stoichiometric quantities (less than the theoretical amount needed for complete oxidation). This partial oxidation approach converts nitrogen oxides to nitrous acid without complete oxidation to nitrate, thereby reducing ozone consumption while maintaining effective nitrogen oxide removal. The process achieves the desired purification effect without the excessive ozone dosage that would lead to complete oxidation and high nitrate formation.
Solution Approach 2:
The patent changes the chemical parameter of oxidation extent by controlling ozone dosage to achieve partial oxidation rather than complete oxidation. By adjusting the oxidation level parameter, the process transforms nitrogen oxides to nitrous acid intermediates that can be absorbed and decomposed, avoiding the formation of stable nitrate byproducts. This parameter change fundamentally alters the reaction pathway and product distribution.
2Reliability
If high concentrations of ozone are introduced to remove nitrogen oxides, then nitrogen oxide removal efficiency is improved, but nitrate byproduct formation increases creating environmental and cost issues
Solution Approach 1:
The patent converts the potentially harmful complete oxidation pathway into a beneficial partial oxidation pathway. By intentionally limiting ozone dosage, the process generates nitrous acid as an intermediate that is more easily absorbed and decomposed into harmless nitrogen gas, carbon dioxide, and water. This converts what would be a harmful byproduct (nitrate requiring disposal) into a beneficial intermediate that decomposes to environmentally benign products.
Solution Approach 2:
The patent extracts or removes the complete oxidation step that leads to nitrate formation. By taking out the excessive oxidation pathway and replacing it with partial oxidation followed by absorption and decomposition, the process eliminates the source of nitrate byproducts while maintaining nitrogen oxide removal effectiveness.
3Productivity
If oxygen enrichment is employed in SO2 generation to increase sulfuric acid throughput, then production capacity is improved, but nitrogen oxide formation increases
Solution Approach 1:
The patent applies blessing in disguise by converting the harmful nitrogen oxide byproduct of oxygen-enriched combustion into a useful intermediate. The nitrogen oxides formed during high-throughput SO2 generation are converted to nitrous acid, which is then absorbed and decomposed into nitrogen gas and other benign products. This allows the system to maintain high productivity while eliminating the harmful emissions that would otherwise result from oxygen enrichment.
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 requirements, minimizes nitrate purge streams, and effectively removes nitrogen oxides while maintaining process efficiency, offering cost savings and improved environmental compliance.
Implementation Method 1
Partial oxidation of nitrogen oxides by ozone in sub-stoichiometric quantities
Implementation Method 2
absorption of nitrous acid in a neutral or acidic medium
Implementation Method 3
which decomposes to nitrogen, carbon dioxide, and water
Data Source
AI summary
The present invention provides for process for inhibiting the levels of nitrogen oxides in process gas streams from sulfuric acid regeneration and sulfuric acid production plants. Partial oxidation of the nitrogen oxides is achieved by feeding a sub stoichiometric amount of ozone as to nitrogen oxides to the process gas stream.