Bonded Core Tube Assembly for Smelting Lance Wear Resistance
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Solution Overview
Problem
Existing direct smelting lances face challenges in withstanding the abrasive nature of metalliferous and carbonaceous materials at high temperatures, leading to potential premature failure of welds connecting wear-resistant sections, which can result in lance failure during extended smelting campaigns.
Innovation Solution
A lance design featuring a core tube assembly with an outer structural material and an inner wear-resistant material bonded together, specifically using stainless steel and ferrochromium white cast iron, to enhance durability and prevent premature weld failure, combined with an annular water cooling jacket for temperature management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wear-resistant material is used for the core tube assembly, then the resistance to abrasive material is improved, but the structural strength and weldability deteriorate
Solution Approach 1:
The core tube assembly is constructed as a composite structure with an inner tube of wear-resistant material (such as ceramic-lined or hardened steel) and an outer tube of structural material (such as stainless steel). The wear-resistant inner tube provides resistance to abrasive metalliferous and carbonaceous materials, while the structural outer tube provides mechanical strength and weldability. This composite construction resolves the contradiction by combining materials that individually excel at different functions.
2Productivity
If the lance operates in high-temperature environment, then the smelting process efficiency is improved, but the lance durability deteriorates
Solution Approach 1:
The lance structure implements local quality by providing temperature-dependent material properties at different locations. The inner wear-resistant tube and outer structural tube are designed with specific thermal properties suitable for high-temperature operation. Additionally, the segmented design with expansion joints allows different parts of the lance to accommodate thermal expansion differently, maintaining durability while operating efficiently at high temperatures.
Solution Approach 2:
The core tube assembly is divided into multiple sections that can expand and contract independently through expansion joints. This segmentation allows each section to manage thermal stress locally, preventing cumulative damage that would reduce durability. The segmented design maintains structural integrity during high-temperature smelting operations while allowing necessary thermal movement.
3Ease of manufacture
If the inner tube is segmented to facilitate assembly, then the ease of manufacture is improved, but the risk of weld failure deteriorates
Solution Approach 1:
Expansion joints serve as intermediary elements between the segmented inner tube sections. These expansion joints provide a controlled interface that accommodates thermal expansion and contraction while maintaining the structural connection. The intermediary design allows segmentation for ease of assembly and maintenance while preventing the propagation of stress that could lead to weld failure, thus resolving the contradiction between manufacturability and reliability.
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 bonded core tube assembly effectively minimizes the risk of lance failure by distributing shear forces and maintaining structural integrity, even with segmented inner tubes, ensuring reliable operation in high-temperature, abrasive environments.
Implementation Method 1
A forced internal cooling water system is provided within the outer annular cooling jacket
Implementation Method 2
an inner tube of a wear resistant material that are bonded together
Data Source
AI summary
A lance for injecting a solid material into a vessel, such as a direct smelting vessel for producing molten iron, has a core tube assembly comprising a passageway for solid material. The core tube assembly has an inlet for receiving solid material at a rear end and an outlet for discharging material at a forward end. The core tube assembly comprises an outer tube of a structural material and an inner tube of a wear resistant material that are bonded together. A method of manufacturing the core tube assembly may include spin casting the outer tube of the structural material; spin casting the inner tube of the wear resistant material onto the inner surface of the outer tube; and metallurgically bonding the tubes together.