Diluted Gaseous Fuel Injection for Sintering Bed Strength
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Solution Overview
Problem
Conventional methods for producing sintered ore in blast furnaces using downward suction type Dwight Lloyd sintering machines face challenges in achieving high strength and yield while maintaining gas permeability, often resulting in insufficient sintering due to inadequate temperature distribution and holding time in the sintering bed.
Innovation Solution
A method involving the charging of fine iron ore and carbonaceous materials, followed by igniting the carbonaceous material and feeding a diluted gaseous fuel with a concentration below the lower limit of combustion into the sintering bed after the ignition furnace, adjusting the ultimate maximum temperature and holding time in the high temperature zone to enhance the combustion and melting zone thickness, thereby improving the cold strength and yield of the sintered ore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pallet moving speed is increased to improve productivity, then the production of sintered ore increases, but the holding time in high temperature zone becomes short, causing insufficient sintering and decreased cold strength
Solution Approach 1:
The diluted gaseous fuel is fed into the sintering bed in advance at a position after the ignition furnace, before the material reaches the high temperature zone. This preliminary action ensures that the fuel is already present and can be combusted when the material passes through the high temperature zone, extending the holding time without increasing the pallet speed.
Solution Approach 2:
The diluted gaseous fuel acts as an intermediary substance that mediates between the ignition furnace and the high temperature zone. It provides additional combustion heat and extends the high temperature exposure time without requiring changes to the pallet moving speed or the basic sintering process.
2Temperature
If the concentration of gaseous fuel is increased to improve combustion, then the temperature increases, but the risk of explosion and fire accident increases
Solution Approach 1:
The concentration of the gaseous fuel is changed from a high concentration (above lower limit of combustion) to a diluted concentration (below lower limit of combustion). This parameter change allows the fuel to be fed safely without immediate combustion, and the combustion occurs gradually as the diluted fuel mixes with air in the sintering bed, reducing explosion risk while still providing the necessary heat.
Solution Approach 2:
Instead of feeding the gaseous fuel at a concentration that would cause immediate combustion (excessive action), the fuel is fed in a diluted state (partial action) below the combustion threshold. This partial feeding approach allows safe introduction of the fuel, and the combustion occurs gradually through mixing with air, providing controlled heating without explosion hazard.
3Strength
If the thickness of combustion and melting zone is increased to improve sintering quality, then the holding time in high temperature zone increases, but the gas flow resistance increases and gas permeability decreases
Solution Approach 1:
The diluted gaseous fuel is fed at a specific local position after the ignition furnace, creating a localized extension of the combustion and melting zone. This local quality change increases the holding time in the high temperature zone without uniformly increasing the thickness throughout the entire sintering bed, thus maintaining gas permeability in other regions.
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 approach effectively increases the cold strength of the sintered ore to 75% or more, improves yield, and maintains gas permeability by extending the holding time in the high temperature zone without increasing the ultimate maximum temperature, leading to higher productivity and better sinter quality.
Implementation Method 1
the carbonaceous material in the sintering bed successively combusts downward. The generated combustion heat brings the sintering raw material combust to melt
Implementation Method 2
The carbonaceous material in the sintering bed is combusted by the suction gas sucked from the top of the sintering bed down to the lower layer portion
Implementation Method 3
By the downward suction of air using wind boxes 11 located below the pallet 8, the carbonaceous material in the sintering bed successively combusts downward
Implementation Method 4
water content in the sintering raw material particles in the sintering bed is vaporized by the heat generated from the combustion of carbonaceous material
Data Source
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AI summary
Provided is the method for producing sintered ore by feeding varieties of gaseous fuels from above the sintering bed of sintering raw material which is charged on the pallet of the sintering machine. The gaseous fuel fed from above the sintering bed on the pallet is a gaseous fuel which is diluted to below the lower limit concentration of combustion. On feeding the gaseous fuel to conduct sintering operation, at least one of a feed position, an ultimate maximum temperature in the sintering bed, and a holding time in high temperature zone is adjusted. Also provided is the sintering machine having the gaseous fuel feed apparatus.