Blast Furnace Lance Segmentation for Coal Combustion
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Solution Overview
Problem
Existing methods for operating blast furnaces face challenges in improving the combustion efficiency of pulverized coal, leading to reduced productivity and increased CO2 emissions, due to issues such as deteriorated oxygen-pulverized coal contact, lance wear, and incomplete combustion within the tuyere and blast pipe.
Innovation Solution
A method involving a double tube upstream lance for blowing solid fuel and combustion-supporting gas, with a downstream lance for injecting flammable gas like LNG, ensuring sufficient oxygen supply for combustion, thereby enhancing the temperature and efficiency of pulverized coal combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If LNG is blown from the triple tube lance to increase pulverized coal temperature, then the temperature increase of pulverized coal is improved, but the contacting property between oxygen and pulverized coal is deteriorated
Solution Approach 1:
The lance is divided into multiple tubes (double tube structure with inner tube and outer tube) that can independently blow different substances. The inner tube blows pulverized coal while the outer tube blows oxygen, allowing separate control of fuel and oxidizer delivery to optimize both temperature increase and contact properties.
Solution Approach 2:
The double tube lance structure nests the inner tube within the outer tube, creating a compact configuration where pulverized coal and oxygen are delivered through concentric pathways. This nested structure allows close proximity of fuel and oxidizer while maintaining independent flow control, improving both heating and contact.
2Adaptability or versatility
If the outside diameter of the triple tube lance is increased to accommodate multiple substances, then the functionality is improved, but the lance cannot be inserted into the existing lance insertion through hole
Solution Approach 1:
Instead of using a single large-diameter triple tube lance, the system segments the delivery function into a smaller double tube lance (inner tube for pulverized coal, outer tube for oxygen) combined with a separate downstream lance for LNG. This segmentation reduces the diameter requirement while maintaining multi-substance delivery capability.
Solution Approach 2:
The system introduces an intermediary approach by using the double tube lance for primary fuel and oxidizer delivery, then adding LNG combustion downstream as a separate stage. This two-stage approach allows each component to be optimized independently, keeping the upstream lance diameter small enough for existing holes while achieving comprehensive functionality.
3Temperature
If LNG is rapidly combusted at the end of the lance to increase temperature, then the temperature increase is improved, but wear damage such as crack and erosion is generated in the end of the lance
Solution Approach 1:
The LNG combustion function is extracted from the upstream lance and relocated to a separate downstream lance position. This extraction removes the high-temperature LNG combustion process from the upstream lance structure, preventing thermal damage while maintaining the temperature increase benefit for pulverized coal combustion.
Solution Approach 2:
The system uses an intermediary two-stage combustion approach where pulverized coal is first delivered and heated by the double tube lance, then LNG is combusted downstream as a separate stage. This intermediary staging allows temperature increase without concentrating all thermal stress on the upstream lance structure.
4Temperature
If pulverized coal is blown from the end of the tuyere to contact with heat oxygen, then the temperature increase of pulverized coal is improved, but there is no time for the pulverized coal to be combusted in the blast pipe and tuyere
Solution Approach 1:
The double tube lance performs preliminary action by delivering pulverized coal and oxygen together in controlled proportions before the coal reaches the tuyere. This preliminary mixing ensures that combustion can begin in the blast pipe and continue through the tuyere, providing adequate combustion time while still achieving temperature increase through controlled oxidation.
Solution Approach 2:
The system applies local quality control by delivering oxygen preferentially around the pulverized coal particles through the outer tube of the double tube lance, creating localized oxidation zones. This localized oxygen supply enables gradual combustion along the blast pipe and tuyere length, providing both temperature increase and sufficient combustion time.
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 improves the combustion efficiency of pulverized coal, increasing productivity and reducing CO2 emissions by ensuring proper oxygen-pulverized coal contact and preventing lance wear, while maintaining operational efficiency.
Implementation Method 1
blowing flammable gas from the downstream lance... LNG is combusted on ahead, so that the temperature of the pulverized coal is increased
Implementation Method 2
when hot air is blown into a blast furnace from a blast pipe through a tuyere
Data Source
AI summary
A method for operating a blast furnace includes blowing pulverized coal and oxygen from an upstream lance configured by a double tube. LNG is blown from a downstream lance on the downstream side in a hot air blast direction, oxygen is supplied from the upstream lance, and the pulverized coal whose temperature has been increased by the combustion of the LNG is combusted along with the supplied oxygen or oxygen in an air blast. With respect to a direction perpendicular to the hot air blast and a downstream direction of the hot air blast, a blowing direction of the LNG from the downstream lance with respect to the blast direction ranges from -30.degree. to +45.degree.. A blast pipe circumferential direction angle at a blowing position of the LNG from the downstream lance with respect to where the upstream lance is inserted into a blast pipe ranges from 160.degree. to 200.degree..