Top Submerged Injection Lance with Gas Flow-Modifying Device
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Solution Overview
Problem
Top submerged lances in pyro-metallurgical operations face challenges with rapid wear and burn-back due to high temperatures and corrosive environments, leading to frequent interruptions and increased operational costs due to the need for frequent lance replacements.
Innovation Solution
A top submerged injecting lance design featuring at least two concentric pipes with a gas flow-modifying device that imparts an inward flow component to the oxygen-containing gas, enhancing mixing with fuel and maintaining a solidified slag coating, thereby reducing wear and extending operational periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the lance is used in top submerged injection to provide efficient oxygen transfer and combustion, then the combustion efficiency is improved, but the lance experiences rapid wear and burn-back due to high temperatures and corrosive slag environment
Solution Approach 1:
A water-cooling system is introduced as an intermediary substance to transfer heat away from the lance. Water is supplied through cooling passages in the lance structure, absorbing excess heat from the high-temperature combustion zone and corrosive slag environment, thereby protecting the lance material from direct thermal exposure and extending its operational life while maintaining combustion efficiency
Solution Approach 2:
The lance is constructed using composite material structures that combine materials with different properties. The lance body may use heat-resistant alloys or ceramic coatings in the high-temperature zones, while other sections use standard materials, creating a composite structure that optimizes both durability and combustion performance across different thermal environments
2Productivity
If the lance operates continuously in high-temperature environment, then productivity is maintained, but the lance requires frequent replacement increasing operational costs and downtime
Solution Approach 1:
The water-cooling system operates automatically and continuously as the lance is lowered into the bath, self-regulating the thermal stress on the lance structure. This self-service cooling mechanism eliminates the need for manual intervention or monitoring, allowing continuous operation without planned maintenance stops for lance replacement
Solution Approach 2:
The water-cooling passages are pre-installed within the lance structure before operation begins. Coolant water is supplied in advance through these passages to prevent thermal damage before it occurs, rather than attempting to repair or replace the lance after wear sets in, thereby eliminating replacement downtime
3Power
If the outer pipe is positioned close to the bath surface for effective injection, then oxygen transfer efficiency is improved, but the pipe is exposed to more intense thermal radiation and faster burn-back
Solution Approach 1:
Water supplied through cooling passages acts as an intermediary heat transfer medium between the hot bath environment and the lance pipe. The water absorbs thermal radiation and convective heat from the molten bath, creating a thermal barrier that protects the pipe material from direct exposure to intense temperatures while allowing the pipe to remain positioned close to the surface for effective oxygen transfer
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 improved lance design enhances fuel combustion efficiency, maintains a protective slag coating at higher temperatures, and increases the operating time between lance replacements, reducing costs and operational disruptions.
Implementation Method 1
a gas flow-modifying device that is disposed in a lower end section of the passage for oxygen-containing gas, adjacent to the chamber, and that is operable to impart an inward flow component, away from the inner surface of the outermost pipe, to oxygen-containing gas passing into and longitudinally within the chamber towards the outlet end of the lance and thereby enhance mixing of the oxygen-containing gas with fuel passing into the chamber from the passage for fuel
Implementation Method 2
The inner pipe may be used to supply feed materials, such as concentrate, fluxes and reductant to be injected into a slag layer of the bath, or it may be used for fuel. An oxygen containing gas, such as air or oxygen enriched air, is supplied through the annulus between the pipes. Prior to submerged injection within the slag layer of the bath being commenced, the lance is positioned with its lower end, that is, the lower end of the outer pipe, spaced a suitable distance above the slag surface. Oxygen-containing gas and fuel, such as fuel oil, fine coal or hydrocarbon gas, are supplied to the lance and a resultant oxygen/fuel mixture is fired to generate a flame jet that impinges onto the slag. This causes the slag to splash to form, on the outer lance pipe, a coating of liquid slag that is solidified by the gas stream passing through the lance to provide the solid slag coating mentioned above
Data Source
AI summary
A lance for top submerged lancing injection in a pyro-metallurgical operation, wherein the lance has at least two substantially concentric pipes, with an annular passage for oxygen-containing gas defined between an outermost one of the pipes and a next adjacent pipe and a further passage for fuel defined within an innermost one of the pipes; the outermost pipe has a lower part of its length, from a submergible lower outlet end of the lance, by which the outermost pipe extends beyond an outlet end of the or each other pipe to define between the outlet end of the outermost pipe and the outlet end of the or each other pipe a chamber with which the passage for oxygen-containing gas communicates; and the lance further includes a defined gas flow-modifying device that is disposed in a lower end section of the passage for oxygen-containing gas.