Ozone Injection in Semi-Dry Scrubbers for NOx Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semi-dry scrubbing technologies face challenges in effectively removing nitrogen oxides due to their non-reactive nature and instability at high temperatures, leading to excessive ozone consumption and potential corrosion issues downstream, while also failing to maintain removal efficiencies for other contaminants.
Innovation Solution
Injecting ozone downstream of the semi-dry scrubber at a specific height within the scrubber volume, where the gas stream temperature is optimal for nitrogen oxides oxidation, allowing for efficient conversion to the pentavalent form without compromising the removal of other contaminants, using a stoichiometric amount of ozone and specific sorbents like lime slurry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ozone is injected upstream of the semi-dry scrubber, then nitrogen oxides oxidation can occur, but significant ozone loss occurs due to decomposition at high temperatures exceeding 325°F
Solution Approach 1:
The patent applies preliminary action by removing contaminants other than nitrogen oxides first in the semi-dry scrubber, then injecting ozone downstream where the gas temperature is lower. This sequencing ensures ozone is injected after the high-temperature zone, preventing decomposition and reducing ozone consumption while maintaining nitrogen oxides removal efficiency.
2Productivity
If excess ozone is used to compensate for decomposition, then nitrogen oxides oxidation can be maintained, but corrosion issues arise in downstream metallurgy and fabric filters are damaged
Solution Approach 1:
The patent removes other contaminants before ozone injection in the semi-dry scrubber, reducing the need for excess ozone. This preliminary cleaning action allows stoichiometric amounts of ozone to suffice, eliminating corrosion problems and fabric filter damage while maintaining nitrogen oxides removal efficiency.
3Productivity
If the semi-dry scrubber operates at high temperatures for effective contaminant removal, then other contaminants are effectively removed, but nitrogen oxides remain unstable and reactive
Solution Approach 1:
The patent performs preliminary removal of other contaminants in the high-temperature semi-dry scrubber zone, then transitions to a lower-temperature zone for ozone injection. This sequential approach allows the gas to cool slightly after initial contaminant removal, creating stable conditions for nitrogen oxides oxidation without compromising overall removal efficiency.
4Productivity
If ozone is injected downstream of the semi-dry scrubber, then nitrogen oxides oxidation occurs effectively, but additional capital equipment is required
Solution Approach 1:
The patent makes the semi-dry scrubber multi-functional by enabling it to perform both traditional contaminant removal and nitrogen oxides oxidation within a single device. By injecting ozone downstream within the scrubber where conditions are appropriate, the system eliminates the need for separate oxidation equipment, reducing capital costs and system complexity.
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 a 35% reduction in ozone usage, maintains high removal efficiencies for nitrogen oxides and other contaminants, reduces corrosion risks, and minimizes fabric filter damage, while ensuring compliance with environmental regulations without requiring additional capital equipment.
Implementation Method 1
oxidizing the nitrogen oxides with ozone downstream of the semi-dry scrubber
Implementation Method 2
contacting the gas stream containing contaminants with a sorbent
Data Source
AI summary
Industrial gas streams such as flue gas streams are treated for nitrogen oxides and other contaminants in dry or semi-dry scrubbers. After the flue gas stream has been contacted with a sorbent, ozone is mixed downstream into the flue gas stream thereby oxidizing the nitrogen oxides and other contaminants. The oxidized contaminants is contacted with sorbent present in the gas stream in the remaining height or volume of the scrubber downstream of ozone injection; and The sorbent is then separated from the flue gas stream leaving the dry or semi-dry scrubber.