SCR Catalyst Modules with Rectangular Channels for Particulate Resistance
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Solution Overview
Problem
Existing catalyst systems for nitrogen oxide reduction in combustion flue gases inadvertently increase sulfur dioxide oxidation, leading to sulfur trioxide formation and corrosion issues, while also being susceptible to clogging by particulate matter from coal combustion, which reduces catalytic performance.
Innovation Solution
The development of catalyst modules with structural catalyst bodies featuring rectangular cross-section flow channels and a chemical composition of 50-99.9 weight percent inorganic oxide and catalytically active metal, combined with a compressible matting material to separate and seal catalyst bodies, enhancing flexural strength and resistance to particulate matter clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If catalyst systems are used for nitrogen oxide reduction, then nitrogen oxide content is reduced, but sulfur trioxide formation increases leading to corrosion issues
Solution Approach 1:
The catalyst body employs different wall thicknesses in different regions: thicker outer peripheral walls (≥2mm) to prevent SO3 formation and corrosion at the exterior surfaces, and thinner inner partition walls (0.5-2mm) to maintain catalytic activity in the interior flow channels. This spatial variation in wall thickness allows simultaneous achievement of corrosion resistance and catalytic performance.
Solution Approach 2:
The catalyst body uses a composite structure combining ceramic materials (e.g., cordierite, mullite, alumina) with specific pore structures and surface coatings. The ceramic substrate provides mechanical strength and thermal stability, while controlled porosity (40-60%) and surface area (200-500 m²/g) enable selective catalysis that reduces NOx while minimizing SO3 formation.
2Productivity
If monolithic catalyst bodies are used in coal-fired environments, then catalytic activity is provided, but particulate matter clogs the cells reducing performance
Solution Approach 1:
The catalyst body is divided into modular segments with rectangular cross-section flow channels instead of traditional hexagonal cells. This segmentation creates larger, more open flow paths that are less susceptible to particulate blockage while maintaining sufficient catalytic surface area through optimized wall thicknesses and channel dimensions.
Solution Approach 2:
The catalyst employs a porous ceramic structure with controlled porosity (40-60%) and specific surface area (200-500 m²/g). The porous nature allows particulate matter to pass through without complete blockage while maintaining high catalytic activity. The pore structure is optimized to prevent ash plugging while preserving catalytic function.
3Strength
If inner partition walls are made longer to increase structural integrity, then flexural strength improves, but flow channel efficiency decreases
Solution Approach 1:
The patent optimizes the length parameter of inner partition walls to be at least 20% shorter than outer peripheral wall segments. This parameter change balances structural requirements (maintaining flexural strength through outer wall segments ≥10mm) with flow efficiency (reducing channel length to minimize pressure drop and improve gas flow). The thickness parameter is simultaneously optimized (0.5-2mm) to compensate for reduced wall length while maintaining mechanical integrity.
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
The solution effectively reduces nitrogen oxide content in flue gases while minimizing sulfur trioxide formation and improving catalytic performance by maintaining structural integrity and preventing particulate matter-induced clogging, even in high particulate environments.
Implementation Method 1
The denitration reaction comprises the reaction of nitrogen oxide species in the gases, such as nitrogen oxide (NO) or nitrogen dioxide (NO2), with a nitrogen containing reductant, such as ammonia or urea, resulting in the production of diatomic nitrogen (N2) and water
Implementation Method 2
Catalyst systems for the removal of nitrogen oxides can increase the amount of sulfur dioxide oxidation since the catalytic material utilized in selective catalytic reduction can additionally effectuate the oxidation of sulfur dioxide
Data Source
AI summary
In one aspect, catalyst modules are described herein comprises structural catalyst bodies having cross-sectional flow channel geometries and surface features for enhanced catalytic activity. In some embodiments, the catalyst modules and associated structural catalyst bodies are suitable for use in high particulate matter environments. Briefly, a catalyst module comprises a framework and a plurality of structural catalyst bodies positioned in the framework, a structural catalyst body comprising an outer peripheral wall and a plurality of inner partition walls forming individual flow channels of rectangular cross-section, the outer peripheral wall resistant to localized flexural failures induced by material between adjacent structural catalyst bodies of the module.