Smelting Start-Up Control via Water-Cooled Element Heat Flux Monitoring
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Solution Overview
Problem
The existing molten bath-based smelting processes, such as HIsmelt and HIsarna, face challenges during start-up due to excessive heat fluxes on water-cooled elements, which can trip the process and lead to unplanned cooling and aborted start-ups, especially when there is insufficient slag in the vessel.
Innovation Solution
Monitoring the heat flux of water-cooled elements to indicate molten bath temperature and adjusting the injection rates of oxygen-containing gas and carbonaceous material to control the bath temperature, preventing critical heat flux levels and ensuring a stable start-up by gradually increasing the slag inventory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If oxygen-containing gas and carbonaceous material are injected into the molten bath to generate heat for smelting, then the smelting temperature increases, but excessive heat fluxes occur on water-cooled elements causing process trips
Solution Approach 1:
The patent implements a feedback control system where heat flux sensors monitor the thermal load on water-cooled elements in real-time. The control system uses this feedback to dynamically adjust the injection rates of oxygen-containing gas and carbonaceous material, preventing excessive heat fluxes that would cause process trips while maintaining sufficient temperature for smelting operations
Solution Approach 2:
The patent changes operational parameters during the start-up sequence by gradually increasing the injection rates of oxygen-containing gas and carbonaceous material rather than maintaining constant high rates. This progressive parameter adjustment allows the molten bath temperature to rise controllably while keeping heat fluxes on water-cooled elements within safe operational limits
2Strength
If the start-up sequence is aborted due to excessive heat fluxes, then water-cooled elements are protected from damage, but the start-up process must be restarted causing loss of time
Solution Approach 1:
The patent applies preliminary action by pre-heating the molten bath and gradually building up the thermal environment before full smelting operations begin. This preliminary heating phase allows water-cooled elements to acclimate to thermal conditions progressively, preventing thermal shock and excessive heat fluxes that would trigger aborts and require restarts
3Object-affected harmful factors
If sufficient slag is present in the vessel during start-up, then heat fluxes on water-cooled elements are reduced, but achieving sufficient slag inventory takes time
Solution Approach 1:
The patent maintains continuous injection of oxygen-containing gas and carbonaceous material throughout the start-up sequence, ensuring continuous heat generation and progressive slag formation. This continuous useful action builds slag inventory steadily over time while simultaneously managing heat fluxes through controlled injection rates, eliminating the need to stop and restart the process
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
This method allows for safe navigation through the critical start-up phase, avoiding high heat fluxes and ensuring successful initiation of the smelting process, maintaining operational stability and reducing the risk of process trips.
Implementation Method 1
monitoring the heat flux of water-cooled elements to obtain an indication of the temperature in the molten bath
Implementation Method 2
supplying solid carbonaceous material and oxygen-containing gas to adjust the heat input into the smelting chamber
Data Source
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AI summary
A method of starting a molten bath-based process for smelting a metalliferous material is disclosed. The method includes using the heat flux of water-cooled elements in lower parts of a smelting vessel to provide an indication of molten bath temperature during at least an early part of the start-up method and adjusting injection rates of oxygen-containing gas and/or carbonaceous material into the smelting vessel to control the molten bath temperature during start-up without exceeding critical heat flux levels and tripping the start-up method.