Catalyst Slurry Coating Uniformity via Resistive Member
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Solution Overview
Problem
The existing methods for coating slurry on monolithic catalyst honeycomb substrates result in uneven distribution, leading to increased manufacturing costs and potential clogging due to slurry agglomerates, as well as reduced exhaust gas purification efficiency in circumferential areas compared to central areas.
Innovation Solution
A coating apparatus that supplies slurry from one end of the substrate and uses air streams and a resistive member to control the flow, ensuring uniform coating by adjusting the distance between the substrate and the resistive member to manage air flow speeds and prevent slurry attachment to the resistive member, thereby optimizing the slurry coat width across channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a resistive member is arranged on the slurry supply side of the honeycomb substrate to decelerate slurry flow in circumferential portions, then the slurry is provided more in the central portion than in the circumferential portions, but the slurry attaches to the resistive member and remains on it, resulting in an increase in the amount of slurry consumed
Solution Approach 1:
The invention extracts the harmful function of the resistive member (causing slurry attachment) while retaining its beneficial function (decelerating air flow). The resistive member is positioned only in the air flow path, not in the slurry flow path, separating the two functions spatially. This allows the resistive member to control air flow without contacting slurry, thus preventing slurry attachment and waste while maintaining the desired slurry distribution pattern.
Solution Approach 2:
The invention introduces an intermediary structure (the resistive member positioned strategically) that mediates between the slurry supply system and the honeycomb substrate. By placing the resistive member in a position where it affects air flow but not slurry flow, it acts as a mediator that controls the coating process without directly interacting with the slurry, thus avoiding contamination and material loss.
2Manufacturing precision
If the slurry attaching to the resistive member dries and hardens, agglomerates of such slurry may be mixed in the liquid slurry to be coated, but if this happens, the agglomerates may enter and clog the channels
Solution Approach 1:
The invention extracts the resistive member from the slurry flow path, eliminating the source of agglomerate formation. By positioning the resistive member only in the air flow path and not in contact with slurry, it prevents slurry attachment and subsequent drying/hardening that would create agglomerates. This separation ensures that the coating process remains clean and free of contaminants that could clog channels.
3Manufacturing precision
If a resistive member is arranged on the slurry supply side, an inorganic oxide included in the slurry acts as an abrasive, and the resistive member is abraded thereby, but the resistive member has to be replaced with a new one after a certain period of time
Solution Approach 1:
The invention extracts the resistive member from the slurry flow path, removing it from the environment where it would suffer abrasion. By positioning the resistive member only in the air flow path, it eliminates contact with abrasive inorganic oxide particles in the slurry. This prevents wear and tear, extending the service life of the resistive member and eliminating the need for frequent replacement, thus improving manufacturing efficiency.
4Productivity
If a larger amount of slurry is coated in the central portion of the honeycomb substrate than in the circumferential portions, then the exhaust gas purification effect is improved in the central portion, but the exhaust gas flowing through the circumferential channels does not pass as smoothly
Solution Approach 1:
The invention applies local quality by creating different flow conditions in different regions of the honeycomb substrate. By positioning the resistive member to decelerate air flow specifically in circumferential channels while leaving central channels unaffected, it creates localized flow control. This allows the central portion to receive more slurry for enhanced purification while maintaining smooth flow in circumferential channels, addressing the contradiction between purification efficiency and flow smoothness.
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 approach reduces manufacturing costs by minimizing slurry waste and ensuring uniform coating, enhancing the quality and performance of monolithic catalysts while maintaining consistent air flow speeds across all channels, thus improving exhaust gas purification efficiency.
Implementation Method 1
air stream generation means for generating air streams flowing through the channels from the one end of the substrate to another end
Implementation Method 2
air stream suppression means, arranged away from said another end of the substrate and facing downstream-side ends of first channels, as viewed in the first direction, for suppressing the air streams in the first channels such that the air streams in the first channels are slower than the air streams in second channels
Data Source
AI summary
A coating apparatus includes: a supply frame for supplying slurry into channels from one end of a honeycomb substrate; and a blower for evacuating a wind box. An annular resistive member is attached to the circumference of the opening of the wind box, and the honeycomb substrate is arranged, with a spacer placed on the resistive member. When the blower is operated and the slurry is supplied, the coat width of the slurry coated on the inner surfaces of the channels in an outer circumferential area is less than the coat width of the slurry coated on the inner surfaces of the channels in a center area.