Blast Furnace Coal Injection Flame Reignition Control
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Solution Overview
Problem
The stability of the flame at the lance tip of pulverized coal injection lances used in blast furnaces is not guaranteed, leading to incomplete combustion of pulverized coal, as existing solutions like flow swirlers and dimples on the inner pipe do not consistently maintain efficient burning conditions.
Innovation Solution
A method that monitors the flame at the lance tip and temporarily reduces the flow of combustive gas to reignite the flame, using existing tuyere blockage detection means such as pressure sensors, light intensity detectors, or cameras to ensure continuous combustion, thereby minimizing unburnt coal injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If flow swirler is provided to improve mixing of pulverised coal and oxygen, then burning efficiency is improved, but device complexity increases and flame stability is not guaranteed
Solution Approach 1:
The invention extracts the flame stabilization function from complex structural modifications (swirlers, dimples) and implements it through a separate, simple stabilization zone at the lance tip where combustive gas is introduced to create a recirculating flow that anchors the flame
Solution Approach 2:
The invention introduces combustive gas as an intermediary substance that mediates between the pulverised coal and the main oxygen supply, creating a stabilization zone that ensures continuous combustion without requiring complex mixing structures
2Productivity
If spiral angle of flow swirler is increased to improve mixing, then burning efficiency improves, but oxygen is directed away from pulverised coal and burning efficiency decreases
Solution Approach 1:
The invention applies different flow characteristics to different zones: the stabilization zone has strong swirling flow for flame anchoring, while the main injection zone maintains straightforward coal-oxygen mixing, allowing each zone to optimize its function without compromising the other
3Reliability
If monitoring and temporary reduction of combustive gas flow is implemented to reignite flame, then flame stability is improved, but control system complexity increases
Solution Approach 1:
The invention implements feedback control by monitoring flame status through detection means and automatically adjusting combustive gas flow accordingly - reducing flow when flame destabilizes to allow reignition, then restoring normal flow when flame is stable
Solution Approach 2:
The stabilization zone with recirculating combustive gas creates a self-stabilizing environment that naturally promotes flame reignition when disturbances occur, reducing the need for complex active control systems
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 ensures quick reignition of the flame and improved combustion efficiency by utilizing existing detection systems, reducing the risk of incomplete combustion and additional installation costs.
Implementation Method 1
light intensity detectors
Implementation Method 2
pressure sensors
Implementation Method 3
allowing the pulverised coal and the combustive gas to form a mixture
Implementation Method 4
conveying pulverised coal... conveying combustive gas
Implementation Method 5
burning the mixture of pulverised coal and combustive gas in the tuyere
Data Source
Figure 1
AI summary
The present invention proposes a method for feeding pulverised coal into a blast furnace, wherein the method comprises the following steps: providing a tuyere stock (14) for blowing hot blast air from a bustle pipe (12) into a furnace hearth of a blast furnace through a tuyere (15) in an opening in the furnace wall (16); providing a pulverised coal injection lance (18) for feeding pulverised coal into the tuyere (15), the pulverised coal injection lance (18) comprising an inner pipe (20) for conveying pulverised coal and an outer pipe (22), coaxially arranged around the inner pipe (20), for conveying combustive gas, the inner pipe (20) forming a separation wall for separating the pulverised coal from the combustive gas, the pulverised coal injection lance (18) having a lance tip (24) arranged in the tuyere (15); allowing the pulverised coal and the combustive gas to form a mixture of pulverised coal and combustive gas at the lance tip (24); burning the mixture of pulverised coal and combustive gas in the tuyere (15); monitoring whether or not a flame at the lance tip (24) is burning; and upon determination that the flame at the lance tip (24) is not burning, reigniting the flame by temporarily reducing the flow of combustive gas through the pulverised coal injection lance (18).