Blast Furnace Stack Gas Injection Reduces Coke Consumption
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Solution Overview
Problem
Blast furnaces face challenges in reducing CO2 emissions while maintaining operational efficiency and extending the lifespan of components, particularly due to the lack of a second level of gas injection which requires modifications that could impact durability and maintenance needs.
Innovation Solution
A blast furnace design incorporating a second level of gas injection in the stack, specifically in the lower part of the stack, using multiple injection outlets around the circumference, without necessitating significant modifications that would compromise durability or increase maintenance requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a second level of gas injection is added in the stack, then CO2 emissions are reduced and coke consumption decreases, but the structural complexity and modification requirements increase
Solution Approach 1:
The gas injection system is segmented into two distinct levels: the conventional tuyere level and the new stack level. This segmentation allows the second injection level to be added independently without disrupting the existing tuyere injection system, thereby reducing overall system complexity while achieving enhanced CO2 reduction
Solution Approach 2:
The injection system is extended from a single horizontal plane (tuyere level) to multiple vertical levels (tuyere level plus stack level). This dimensional expansion enables CO-rich gas to be injected at different heights in the stack, creating additional reduction zones without significantly increasing horizontal complexity
2Productivity
If a second level of gas injection is added in the stack, then productivity and reduction efficiency increase, but the durability and maintenance requirements of furnace components may be compromised
Solution Approach 1:
The injection outlets at the stack level are specifically positioned and designed to match the local conditions of the reduction zone. The gas is injected at optimal locations where it can effectively participate in reduction reactions without creating localized overheating or mechanical stress that would compromise stave durability
Solution Approach 2:
The design anticipates potential thermal and mechanical stresses from the new injection level by carefully selecting injection parameters and outlet positions. This prevents excessive thermal loading on staves and maintains structural integrity, avoiding premature maintenance requirements
3Loss of substance
If CO-rich top gas is injected at the tuyere level, then coke consumption is reduced, but the gas composition adaptation requirements increase
Solution Approach 1:
The stack-level injection system acts as an intermediary that handles the CO-rich top gas with composition more suited to upper reduction zones. This separates the gas composition adaptation requirement from the tuyere injection system, allowing each level to operate with gas compositions optimized for its specific zone without requiring complex adaptation of the other system
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 design reduces coke consumption and CO2 emissions by effectively utilizing CO-rich top gases as a reducing agent, while maintaining the durability and operational efficiency of the blast furnace, thus avoiding increased maintenance or shortened lifespan.
Implementation Method 1
the conversion of the iron-containing charge (sinter, pellets and iron ore) to cast iron is conventionally carried out by reduction of the iron oxides by a reducing gas (in particular containing CO, H2 and N2)
Implementation Method 2
combustion of coke at the tuyeres located in the bottom part of the blast furnace where air preheated to a temperature between 1000° C. and 1300° C., called hot blast, is injected
Implementation Method 3
A second level of gas injection is incorporated in the stack, specifically in the lower part of the stack, using multiple injection outlets around the circumference
Data Source
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AI summary
A blast furnace for ironmaking production wherein iron ore is at least partly reduced by a reducing gas which is injected in the stack of the blast furnace. The blast furnace comprises an external wall, an internal wall in contact with matters charged into the blast furnace, said internal wall comprising several rows of staves having a parallelepipedal shape. At least one row of staves comprises staves with a hole drilled in a least one of the corners of the parallelepipedal stave wherein an injection device may be partly inserted in.