Honeycomb Filter Catalyst Zoning for Thermal Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing exhaust gas purifying systems using honeycomb filters face issues with thermal stress and low regeneration limit values due to abnormal temperature rises during the regeneration process, leading to potential damage and breakage of the filters.
Innovation Solution
An exhaust gas purifying system is designed with a catalyst carrier and a honeycomb filter arranged in a metal casing, where the catalyst carrier is placed upstream of the honeycomb filter, and a catalyst supporting layer is formed on a specific area of the honeycomb filter to distribute heat generation and maintain thermal conductivity, preventing excessive temperature differences and thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a catalyst supporting layer is formed on the honeycomb filter to improve PM burning performance, then the regeneration limit value increases, but the thermal stress on the filter increases due to heat generation
Solution Approach 1:
The patent divides the honeycomb filter into multiple zones with different catalyst supporting layer configurations. The upstream side has a catalyst supporting layer for PM burning, while the downstream side has no catalyst supporting layer to act as a heat dissipation zone, segmenting the thermal management functions across different regions of the filter
Solution Approach 2:
The patent applies different properties to different parts of the honeycomb filter: the upstream side has high catalyst loading for active PM oxidation, while the downstream side has zero catalyst loading to provide thermal relief and reduce thermal stress, creating local quality differences that optimize both regeneration performance and thermal management
2Productivity
If the catalyst carrier is placed close to the honeycomb filter to improve heat utilization for PM burning, then the regeneration efficiency increases, but the temperature difference between upstream and downstream sides increases causing thermal stress
Solution Approach 1:
The patent segments the exhaust gas purification function into two distinct components: a catalyst carrier for toxic gas conversion and a honeycomb filter for PM capture and burning. The spatial separation between these components (10-200mm distance) allows heat from the catalyst carrier to预热 the honeycomb filter without creating excessive thermal gradients within the filter itself
Solution Approach 2:
The exhaust gas flow acts as an intermediary medium that transfers heat from the catalyst carrier to the honeycomb filter in a controlled manner. The gas flow carries thermal energy from the upstream catalyst carrier region to the downstream honeycomb filter, enabling heat utilization while distributing thermal energy gradually rather than creating concentrated hot spots
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention aims to provide an exhaust gas purifying system which can restrain an abnormal rise of temperature upon purifying exhaust gases and has an improved regeneration limit value. The exhaust gas purifying system of the present invention comprises: a catalyst carrier on which a catalyst is supported; and a honeycomb filter including a pillar-shaped honeycomb fired body having a large number of cells longitudinally disposed in parallel with one another with a cell wall therebetween, with either one end of each of the cells being sealed, the catalyst carrier being placed in an exhaust gas passage on the upstream side of the honeycomb filter, wherein the catalyst carrier is placed at a predetermined distance from the honeycomb filter; in the honeycomb filter, no catalyst supporting layer is formed in the area covering 10% of the overall length of the honeycomb filter from the end face on the outlet side from which exhaust gases flow out; in the honeycomb filter, out of the area covering 90% of the overall length of the honeycomb filter from the end face on the inlet side to which the exhaust gases flow in, a catalyst supporting layer is formed in an area covering 25 to 90% of the overall length of the honeycomb filter; and in the honeycomb filter, a thermal conductivity of the area with the catalyst supporting layer being not formed therein is higher than a thermal conductivity of the area with the catalyst supporting layer being formed therein.