stackMonitor – Online Blast Furnace Stack Status Monitoring

Initial situation:

• The decreasing and fluctuating quality of raw materials and the aim to maximise PCI and decrease coke rates force European blast furnaces to operate closer to operational limits. At same time productivity and efficiency must be raised to survive in global competition. High stack permeability and stable gas distribution become most important.
• Analysis and control of the stack processes is difficult: Hundreds of  measurement values are available nowadays, but they are distributed around the blast furnace and just show indirect “fingerprints” from outside instead of the real internal process information needed (e.g. position of process zones).
• New measurement techniques deliver very fast, full 2D information of the top (acoustical gas temperature, burden profile radar), but they are not sufficiently validated and not investigated by research. Instead, the operators are overcharged with even more separate measurement data. No overall process information is available to decide about control actions.

Working topics:

• New top measurements will be validated. The influences acting on the top gas temperature measured by a 2D acoustical system will be investigated on different time scales to separate overlapping effects. CFD-DEM-simulations will support the investigations with new fundamental knowledge.
• The structure and descent of each burden / coke layer in the BF stack will be determined. A permeability indicator for each charged layer will be determined exploiting short-time changes of the acoustical top gas temperature. This data will be coupled with the change of material properties during descent including the interrelation to the gas flow, by a CFD-DEM model and comprehensive lab trials.
• Information about the gas flow through deeper stack zones from 2D top gas temperature measurement will be combined with vertical pressure measurements to estimate the cohesive zone profile. Furthermore, CFD flow simulations, online connected to measured data, will be established to determine the stack process zones.
• Merger of information from above steps in online stack monitoring tools, indicating temperature distribution, reaction zones and gas flow. The online tools will be used and validated in industrial environment for recommendation of control actions.

Results:

• Blast Furnace Stack online monitoring for appropriate control against non-ideal stack states.

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