Suppressing Carbon Refractory Rear Face Oxidation via Silicate Coating
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Solution Overview
Problem
Existing methods for suppressing rear face oxidation of carbon-containing refractories in high-temperature facilities are either costly, inefficient, or prone to air leakage, leading to increased refractory wear and maintenance costs.
Innovation Solution
Applying an alkali metal silicate aqueous solution with a specific molar ratio of SiO2 to alkali metal oxide to the rear face of the refractory, which forms a solid adherent layer that enhances airtightness and reduces oxidation, using sodium silicates specified in Japanese Industrial Standard JIS K1408-1966, and applying it multiple times to achieve a uniform thickness of 0.1 to 0.4 mm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal plate protection sheet is placed between the outer steel shell and the refractory, then rear face oxidation is suppressed, but air leakage occurs through gaps and the protection effect is insufficient
Solution Approach 1:
The patent uses a flexible sheet material impregnated with antioxidant composition to fill gaps between the protection sheet and refractory surface. This flexible material conformally seals irregular surfaces and gaps, preventing air leakage while maintaining the protective function against oxidation.
Solution Approach 2:
The patent introduces an intermediary flexible sheet impregnated with antioxidant composition between the rigid metal protection sheet and the refractory surface. This intermediary material fills gaps and seals air pathways, mediating between the rigid protection structure and the refractory surface to achieve complete sealing.
2Reliability
If the composition of the refractory is changed in the lining thickness direction to suppress oxidation, then oxidation resistance improves, but production costs and maintenance costs increase
Solution Approach 1:
The patent applies antioxidant composition locally to the rear face surface of the refractory where oxidation occurs, rather than changing the composition of the entire refractory lining. This localized treatment provides oxidation resistance at the critical surface while maintaining the original refractory composition and structure throughout, reducing production complexity and cost.
Solution Approach 2:
The patent creates a composite structure by impregnating the rear face surface of the refractory with antioxidant composition, forming a protective layer with different properties than the bulk refractory. This composite approach provides oxidation resistance at the surface while maintaining the mechanical and thermal properties of the original refractory, avoiding the need for complex compositional gradients.
3Strength
If carbon or carbon compound is added to improve durability, then thermal conductivity and binder effect improve, but rear face oxidation increases and porosity increases
Solution Approach 1:
The patent converts the harmful oxidation of carbon into a beneficial process by allowing controlled oxidation of carbon on the rear face to form a protective layer. This layer, while containing oxidized carbon, provides barrier properties that prevent further oxidation penetration into the refractory interior, thus protecting the carbon-containing structure from severe degradation.
Solution Approach 2:
The patent applies antioxidant composition to the rear face surface before oxidation can severely damage the refractory. This preliminary protective measure prevents or slows down the oxidation of carbon, maintaining the integrity and low porosity of the refractory structure while still allowing controlled oxidation to form a protective barrier.
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 method effectively suppresses rear face oxidation, increasing the refractory's durability and reducing maintenance needs, while maintaining high airtightness and refractory performance without degrading the fire resistance or causing significant cost increases.
Implementation Method 1
forming a adherent layer on a rear face of a carbon-containing refractory by applying an alkali metal silicate aqueous solution to the rear face and then solidifying the alkali metal silicate aqueous solution
Implementation Method 2
the rear face is oxidized and an oxidized layer is formed on the rear face side of the carbon-containing refractory
Data Source
AI summary
Provided is a method for suppressing rear face oxidation and a lining structure, with which high airtightness and a great effect of suppressing rear face oxidation are obtained. The method for suppressing rear face oxidation of a carbon-containing refractory includes forming an adherent layer on a rear face of a carbon-containing refractory by applying an alkali metal silicate aqueous solution to the rear face and solidifying the alkali metal silicate aqueous solution. The alkali metal silicate aqueous solution contains an alkali metal oxide R2O (R is an alkali metal element) and SiO2 and has a molar ratio of SiO2 to the alkali metal oxide of 2.3 or more. The carbon-containing refractory is used at a high temperature of 400° C. or more and contains 1 mass % or more of carbon or a carbon compound.