Flue Gas Mixing Unit for SCR Catalyst Cooling
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Solution Overview
Problem
Existing flue gas purification systems for fossil fuel and green fuel power generators struggle to efficiently cool and treat flue gases at high temperatures, limiting the effectiveness of catalysts in removing nitrogen oxides (NOx) and carbon monoxide (CO).
Innovation Solution
A reduction system incorporating a mixing unit with a static turbulence creating system to homogeneously mix a cooling fluid and hot flue gases, followed by injection of a NOx reduction agent vapor, which is then cooled and treated with an SCR catalyst to remove NOx and optionally CO.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If flue gas is cooled down using a cooling fluid to enable SCR catalyst to remove NOx, then the temperature is reduced to a suitable range for catalyst operation, but the system complexity increases due to the need for additional cooling fluid supply systems and mixing devices
Solution Approach 1:
The patent combines the cooling fluid supply function and the NOx reduction agent injection function into a single integrated injection system. The same injection device delivers both the cooling fluid and the NOx reduction agent through shared conduits and injection points, merging two separate systems into one unified system that performs dual functions simultaneously.
Solution Approach 2:
The injection system is designed with multi-functionality, where a single system performs both cooling the flue gas and delivering the NOx reduction agent. The injection device can switch between or simultaneously deliver different fluids (cooling fluid and reduction agent) through the same hardware infrastructure, making the system universal in its operational capabilities.
2Quantity of substance
If standard catalysts are used that work at temperatures up to 470°C, then the catalyst cost is reduced, but the flue gas must be cooled down from 500-700°C which requires additional cooling systems
Solution Approach 1:
The system performs preliminary cooling of the flue gas before it reaches the catalyst using the integrated cooling fluid injection. This preliminary action reduces the flue gas temperature from 500-700°C to the 470°C range where standard, cost-effective catalysts can operate efficiently, avoiding the need for more expensive high-temperature catalysts while maintaining cost advantages.
3Temperature
If a dilution or tempering system is applied to cool down flue gas, then the temperature is reduced to appropriate levels, but the equipment cost and system complexity increase
Solution Approach 1:
The patent merges the tempering/cooling function with the NOx reduction agent injection function into a single integrated system. By combining these two functions that were previously separate (cooling system and injection system), the patent reduces the total equipment cost and simplifies manufacturing compared to having independent cooling and injection systems.
4Reliability
If separate tools are used for cooling flue gas and injecting NOx reduction agent, then each function can be optimized independently, but the number of components and system complexity increases
Solution Approach 1:
The patent combines separate cooling and injection functions into a single integrated injection system that delivers both cooling fluid and NOx reduction agent through shared hardware. This merging reduces the number of separate components and simplifies the system architecture while maintaining the ability to independently control and optimize each fluid delivery through separate control mechanisms.
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 configuration effectively cools the flue gas to a temperature suitable for catalysts, ensures good distribution of the NOx reduction agent, and achieves significant reduction of NOx and CO emissions, while minimizing equipment and costs.
Implementation Method 1
a static turbulence creating system which is configured to create a turbulence inside the mixing unit during operation in the cooling fluid and the flue gases, in such a way homogeneously mixing these
Implementation Method 2
one or more vaporizers for vaporizing a liquid NOx reduction agent to a NOx reduction agent vapor, wherein the one or more vaporizers optionally are heat exchangers
Implementation Method 3
one or more vaporizers optionally are heat exchangers
Implementation Method 4
at least one selective catalytic reduction (SCR) catalyst located in the flue gas passage downstream the mixing unit, the SCR catalyst being configured to remove NOx from the cooled flue gas mixture
Data Source
Figure 1
AI summary
The present disclosure relates to reduction system 1 for flue gas produced by a fuelled power generator, comprising an exhaust duct arrangement 2 with a flue gas passage, and a reduction agent injection system 3 . The latter comprises one or more vaporizers for vaporizing a liquid reduction agent to a vapor, and one or more injectors for injecting the vapor into a respective cooling fluid passage 22. One or more mixers located in a respective cooling fluid passage are configured to mix the cooling fluid with the vapor injected in the cooling fluid passage, obtaining a reduction agent-cooling fluid mixture. A mixing unit 25 with a static turbulence creating system located in the flue gas passage 21 is configured to obtain a homogeneous cooled flue gas mixture out of the reduction agent-cooling fluid mixture and the hot flue gas. At least one SCR catalyst 26 placed in the flue gas passage downstream the mixing unit removes NOx out of the cooled flue gas mixture. Also a CO reduction catalyst can be provided, separated from or integrated with the SCR catalyst, to remove CO out of the cooled flue gas mixture.