Gas Injection Nozzle Refractory Durability
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Solution Overview
Problem
Existing gas injection nozzles with small metal tubes buried in carbon-containing refractories suffer from inadequate durability due to thermal shock and carburization, leading to premature damage and reduced lifespan.
Innovation Solution
A method involving non-oxidative firing and organic substance impregnation of the carbon-containing refractory multiple times, optimizing conditions to enhance fracture energy and prevent carburization of the small metal tubes, thereby improving the nozzle's durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small metal tubes are buried in carbon-containing refractory for gas injection, then gas injection function is achieved, but the metal tubes suffer from carburization and thermal shock damage reducing durability
Solution Approach 1:
A refractory sintered body is introduced as an intermediary layer between the carbon-containing refractory and the small metal tubes. This sintered body acts as a protective barrier that prevents direct contact between the carbon-containing refractory and the metal tubes, thereby suppressing carburization while maintaining thermal shock resistance. The sintered body serves as a mediator that protects the metal tubes from harmful effects without compromising the overall structure.
Solution Approach 2:
The gas injection nozzle is constructed as a composite structure combining carbon-containing refractory, refractory sintered body, and small metal tubes. The refractory sintered body is integrated into the carbon-containing refractory matrix, creating a multi-material composite that leverages the advantages of each material: the carbon-containing refractory provides structural integrity and thermal stability, while the refractory sintered body provides protection against carburization and thermal shock for the metal tubes.
2Reliability
If refractory sintered body is placed between small metal tube and carbon-containing refractory to suppress carburization, then metal tube protection is improved, but it becomes difficult to place in narrow spaces with many small metal tubes
Solution Approach 1:
The refractory sintered body is formed in advance as a protective layer on the inner surface of the gas injection nozzle before the small metal tubes are buried. This preliminary formation of the sintered body allows it to be pre-positioned in the narrow spaces, and then the small metal tubes can be easily embedded into the pre-formed sintered body structure, significantly simplifying the installation process compared to trying to fit the sintered body around pre-positioned tubes.
Solution Approach 2:
Instead of placing the refractory sintered body around the small metal tubes (the conventional approach), the invention inverts the sequence by forming the sintered body first on the nozzle inner surface, then embedding the small metal tubes into the sintered body. This reversal of the traditional assembly sequence allows the sintered body to be pre-formed in narrow spaces and then accommodates the metal tubes, making manufacturing much easier.
3Reliability
If oxide layer is formed on small metal tubes to suppress carburization, then some protection is achieved, but the oxide layer thickness is insufficient after extended operation
Solution Approach 1:
The refractory sintered body serves as a permanent intermediary protective layer that replaces the insufficient oxide layer. Instead of relying on a thin oxide layer that degrades over time, the sintered body provides a thick, stable physical barrier that continuously protects the metal tubes from carburization throughout the extended service life of the gas injection nozzle.
Solution Approach 2:
The protection mechanism changes from a chemical oxide layer (thin, degradable) to a physical refractory sintered body layer (thick, stable). This parameter change in the protective layer's thickness and material composition ensures long-term durability and maintains effective carburization suppression throughout the extended operational life of the nozzle.
Data Source
AI summary
A method of producing a gas injection nozzle refractory in which one or more small metal tubes for gas injection are buried in a carbon-containing refractory, comprises performing a series of processes a plurality of times, the series of processes involving subjecting the carbon-containing refractory with the small metal tubes buried therein to non-oxidative firing and thereafter performing an impregnation treatment in which the carbon-containing refractory is impregnated with an organic substance having a residual carbon ratio of 30 mass% or more. As a result of performing non-oxidative firing and organic substance impregnation a plurality of times, the fracture energy of the carbon-containing refractory with the small metal tubes buried therein is increased, and, during use of a gas injection nozzle, the propagation of cracks initiated due to sharp temperature gradients near the working surface of the nozzle is suppressed. This significantly improves the life of the gas injection nozzle.