Seawater Scrubber Ozone Oxidation Nitrogen Oxides
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Solution Overview
Problem
Existing methods for removing nitrogen oxides from gas streams using seawater scrubbing generate significant amounts of nitrate/nitric acid by-products, requiring additional treatment and increasing costs, and often necessitate separate scrubbing equipment for nitrogen oxides control, which is costly and inefficient.
Innovation Solution
The method involves contacting the gas stream with ozone to oxidize nitrogen oxides, followed by a droplet separator or condensing surface to capture the oxidized nitrogen oxides, allowing for their removal without contaminating the scrubber purge with nitrates/nitric acid, thereby enabling the use of seawater in a once-through mode and minimizing the need for additional scrubbing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If seawater scrubbing is used to remove nitrogen oxides from gas streams, then nitrogen oxides are removed from the exhaust gas, but significant amounts of nitrate/nitric acid by-products are generated requiring additional treatment
Solution Approach 1:
The patent extracts the nitrogen oxides removal function from the seawater scrubbing system by adding a separate ozone injection system. The ozone oxidizes nitrogen oxides to higher oxides that can be selectively removed, separating this function from the main scrubbing process that handles sulfur oxides and particulates. This extraction prevents nitrate formation in the scrubber purge while maintaining effective nitrogen oxides removal.
Solution Approach 2:
Ozone is introduced as an intermediary substance that mediates the conversion of nitrogen oxides to higher oxides (NO2, N2O3, N2O4, N2O5). These intermediate oxidation products have different solubility characteristics that allow selective removal without forming nitrate by-products in the seawater scrubbing system.
2Object-affected harmful factors
If separate scrubbing equipment is added for nitrogen oxides control, then nitrogen oxides removal efficiency is improved, but capital and operational costs increase
Solution Approach 1:
The patent merges the nitrogen oxides oxidation function with the existing seawater scrubbing system by injecting ozone into the gas stream before it enters the scrubber. This combination allows the single scrubbing system to handle both sulfur oxides and nitrogen oxides without requiring separate equipment, reducing capital and operational costs while maintaining removal efficiency.
Solution Approach 2:
The modified scrubbing system achieves multi-functionality by simultaneously removing sulfur oxides, nitrogen oxides, and particulates through the combined action of ozone oxidation and seawater scrubbing. This universal approach eliminates the need for dedicated nitrogen oxides scrubbing equipment while maintaining effective control of all major exhaust contaminants.
3Quantity of substance
If ozone is used to oxidize nitrogen oxides to higher oxides, then nitrogen oxides become more soluble and removable, but the process requires additional energy input
Solution Approach 1:
The patent changes the oxidation state parameter of nitrogen oxides by introducing ozone, converting NO to higher oxides (NO2, N2O3, N2O4, N2O5) that have significantly higher water solubility. This parameter change enables effective removal of nitrogen oxides through the existing seawater scrubbing system without requiring additional energy-intensive equipment.
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 the volume of nitrate/nitric acid formed, eliminates the need for separate nitrogen oxides scrubbing equipment, and allows for safe discharge of the scrubber purge, lowering operational and capital expenses while maintaining environmental responsibility.
Implementation Method 1
Contacting the gas stream with ozone, wherein nitrogen oxides are oxidized
Implementation Method 2
Contacting the gas stream containing the oxidized nitrogen oxides with a device selected from the group consisting of a droplet separator and a condensing surface, thereby removing the oxidized nitrogen oxides
Implementation Method 3
Seawater is mildly alkaline and generally used in once through mode to neutralize the acidic components present in the seawater to form salts
Data Source
AI summary
A method for removing contaminants from a gas stream by feeding the gas stream into a scrubber that can use seawater as the scrubbing medium. The gas stream is first scrubbed with the seawater and then mixed with ozone to remove the contaminants. Nitrogen oxides that are present in the gas stream are converted to nitric acid/nitrates and these are recovered via condensate or coalesced mist for neutralization. The treated gas stream is then treated by a second scrubber whereby other contaminants such as sulfur oxides, particulates and the like are removed and the thus treated gas stream is exhausted to the atmosphere. Optionally a droplet separator may be present in the scrubber.