Urea SCR Mat Material Composition for Holding Force Retention
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Solution Overview
Problem
Conventional mat materials used in urea SCR systems experience a reduction in surface pressure and holding force over time, compromising the sealing effectiveness in exhaust gas purifying apparatuses.
Innovation Solution
A mat material composed of glass fibers with a specific composition (52-66% SiO2, 9-26% Al2O3, 15-27% CaO, 0-9% MgO, 0-4% TiO2, 0-5% ZnO, and 0-2% Na2O+K2O, with minimal B2O3 content, and optionally including an organic binder and expansive agents, is used as a holding sealing material to maintain surface pressure and enhance shear strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mat material is used as holding sealing material in urea SCR system, then initial holding force is sufficient, but holding force and surface pressure are lowered over operating time
Solution Approach 1:
The invention changes the chemical composition parameters of glass fibers by specifying precise ranges of SiO2 (52-66%), Al2O3 (9-26%), CaO (15-27%), and limiting B2O3 to 0-2%, while controlling Na2O+K2O content to 0-2% total. These parameter changes make the glass fibers resistant to chemical reactions with urea and ammonia, preventing deterioration over operating time and maintaining holding force and surface pressure throughout the service life of the exhaust gas purifying apparatus
2Ease of manufacture
If glass fibers react with urea and alkaline components, then mat material can be initially formed, but holding force is lowered over time due to deterioration
Solution Approach 1:
The invention modifies the chemical composition parameters of glass fibers to achieve resistance against chemical reactions. By controlling SiO2 content at 52-66% and CaO at 15-27%, the glass fibers maintain their structural integrity when exposed to urea and ammonia, preventing deterioration while preserving ease of manufacture through standard mat material formation processes
Solution Approach 2:
The invention replaces conventional glass fibers that deteriorate over time with specially composed glass fibers that resist chemical reactions. This substitution eliminates the need for frequent replacement of the holding sealing material, transforming it from a short-lived component requiring maintenance into a durable material that maintains its holding force throughout the entire operating life of the exhaust gas purifying apparatus
Data Source
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AI summary
The present invention aims to provide a mat material with a holding force that is less likely to be lowered. The mat material of the present invention is a mat material including glass fibers, the glass fibers containing 52 to 66% by weight of SiO2, 9 to 26% by weight of Al2O3, 15 to 27% by weight of CaO, 0 to 9% by weight of MgO, 0 to 4% by weight of TiO2, 0 to 5% by weight of ZnO, and 0 to 2% by weight of Na2O and K2O in total, and being substantially free of B2O3.