Measuring layer thickness and rate of descent in blast furnaces
Optimization of the blast furnace process and increased application of secondarycombustibles can lower the consumption of coke in hot metal production.
Due to high and still rising expense for coke and the environmental impact of coke production the reduction of the required coke amount is both economical and ecologically essential.
Beyond it’s function as a reducing agent the coke contributes to the formation of mechanically stable layers and ensures an evenly gas flow.
With minimization of the coke layer thickness that is associated with the reduction of coke deployment maintaining this mechanical stability will get increasingly demanding.
Uneven gas flow or the build-up of deposits can lead to unfavourable operating conditions.
If not detected at an early stage these progressions can lead to severe consequences for the blast furnace process. For a best possible operation of the blast furnace hence information on the composition and the movement of the layers is essential.
The Citobloc principle of measurement supplies and records this information continuously.
In contrast to profilemeters that merely retrieve the surface of the blast furnace fill the Citobloc system acquires information on layer thickness, rate of descent and the local distribution of material.
Interferences will be detected more quickly, the furnace can be operated closer to it’s optimum working point, productivity and the life cycle of the blast furnace will be increased.
Overview of the
The Citobloc system provides information on:
- Material of the individual layers (coke or burden)
- Actual thickness of the different material layers
- Descent rates of the blast furnace fill
- Interferences of the fill’s descent
All information is available in real-time as well as a history.
By exact knowledge of this measured values consequently the blast furnace process can be significantly optimized and the yield can be increased.
Moreover anomalies, e.g. build-ups of deposits on the blast furnace perimeter can be identified at an early stage.
This way the Citobloc system serves as decision guidance for taking appropriate counter measures.
The life cycle of the blast furnace will be prolonged by the increased symmetry of the process and cost will be reduced.
The configuration of the material layers is determined by means of four measuring structures on the blast furnace.
Each structure consists of two electrodes inserted through the shell with a vertical offset. The electrodes, made of highly temperature-resistant and abrasion-resistant materials, immerse into the fill of the blast furnace. The service life of the electrodes amounts to several years. Wear of the electrodes will be detected by the system automatically to avoid erroneous measurements.
The measuring structure can be placed at a level of approx. 5 m below the furnace top.
The physical effect used is a combination of resistivity measurement and current run-time measurement. With this method the material in the surrounding area of each electrode can be identified.
After cycling through a defined measuring-cycle the material formation of the layers level with the measuring structures is determined.
The measuring cycle is controlled by the system’s electronics, which can be placed up to several hundred meters away from the measuring structures. The analysis of the measured values is then conducted in a computer, that again can be located up to 1000 m away from the measuring electronics.
The software of the Citobloc system consists of four modules:
- Data acquisition
- Data processing
- Graphical presentation
- Link to the process control system
The data acquisition is running all time and constantly stores the raw data to the computers hard disk.
The data processing calculates the resulting data (e.g. material, layer thickness, descent rate) from the raw data.
The graphical presentation module displays raw data and resulting data adapted to the needs of the operator. This module can also be run on a remote system via a network connection.
By means of defined interfaces the data can be made available to the process control system.
For further information download the Citobloc produkt info :
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