Labyrinthine Refractory Tile System for Furnace Wall Protection
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Solution Overview
Problem
Existing refractory systems for lining high-temperature furnaces or boilers, such as those in waste incineration plants, lack comprehensive protection against corrosive gases, slag, oxygen, ash, debris, and other objects between separate refractory elements, leading to potential damage to tube sheets.
Innovation Solution
A refractory tile system comprising a base tile with attachment points for mounting and an evacuation channel, combined with a shielding tile featuring protrusions and overhangs that create a stable, labyrinthine structure to prevent gas and solid penetration, using silicon carbide (SiC) or nitride-bonded silicon carbide (nSiC) for the base tile and non-porous silicon-infiltrated silicon carbide (SiSiC) for the shielding tile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate refractory elements are used with gaps between them, then installation and replacement become easier, but protection against corrosive gases and slag penetration is reduced
Solution Approach 1:
A refractory mortar is introduced as an intermediary substance to fill the gaps between separate refractory elements. This mortar creates a continuous protective barrier that prevents corrosive gases and slag from penetrating through the joints, while still allowing the individual tiles to be installed and replaced independently.
Solution Approach 2:
The refractory system employs a layered structure where a dense refractory layer is positioned against the tube sheet, followed by an insulating refractory layer on the outer side. This nested arrangement provides both protection and insulation while maintaining the benefits of separate installable elements.
2Use of energy by moving object
If refractory tiles are made with high SiC content for high heat transfer, then energy efficiency improves, but oxidation resistance deteriorates above 900°C
Solution Approach 1:
The refractory system uses composite material construction with inner layer containing 85-95% SiC for high heat transfer efficiency, and outer layer containing 95-99% SiC with aluminum oxide coating for oxidation resistance. This composite approach allows both high heat transfer and oxidation resistance to coexist in different layers of the same system.
Solution Approach 2:
Different regions of the refractory system are assigned different material compositions optimized for their specific functions: the inner layer closer to the tube sheet uses high SiC content for maximum heat transfer, while the outer layer uses higher purity SiC with protective coating for oxidation resistance, where it is most needed.
3Reliability
If nSiC tiles are pre-fired in absence of oxygen to create nitride bond, then initial oxidation resistance improves, but long-term stability deteriorates due to eventual oxidation
Solution Approach 1:
An outer refractory layer with aluminum oxide coating is applied beforehand to protect the inner nSiC layer from oxidation. This protective outer layer acts as a cushion against oxidative environments, allowing the nSiC tiles to maintain their oxidation resistance throughout their service life without degrading.
Solution Approach 2:
The system combines pre-fired nSiC tiles for the inner layer with an outer layer of high-purity SiC and aluminum oxide coating. This composite structure allows the nSiC to provide excellent initial oxidation resistance while the outer protective layer ensures long-term stability by preventing oxygen penetration over time.
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 system provides enhanced protection against corrosive gases, slag, and debris by ensuring stable mounting, preventing gas transfer, and inhibiting mechanical and chemical damage to the interior walls of furnaces or boilers, thereby extending the lifespan of refractory tiles.
Implementation Method 1
SiC has a high heat transfer rate, allowing a maximum amount of energy to flow to the tube sheets
Implementation Method 2
Because SiC is sensitive to oxidation above 900°C, the tiles may be pre-fired in the absence of oxygen and a nitride bond is created. However, after some time in use, generally after about 3 to 5 years, nSiC-tiles will also become sensitive to oxidation, and at a certain moment they will start to oxidise
Data Source
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AI summary
The present invention relates to refractory tile systems for covering an internal wall of a high temperature furnace or boiler, comprising a base tile having a front face and a back face, and a shielding tile having a front face and a back face, wherein the said back face of said base tile comprises one or more attachment points for mounting the base tile to the said internal wall using an anchoring system, and wherein the said shielding tile is equipped with a protrusion along a first side, extending from the back face of the shielding tile and adapted to stably arrange the shielding tile in a suspended position from the said base tile when mounted to the said internal wall, and an overhang along a second side opposite the said first side and extending from the front side of the shielding tile, such that in a mounted position, the said overhang partially covers an adjacent shielding tile.