Abstract:
Controlling the thermal level of the Blast Furnace is essential to achieve the best results of: production, cost and quality. The thermal control basically depends on the management of the process by the operational team and the oscillation of the moisture of the raw materials charged. Charcoal, as a hygroscopic product (high capacity to absorb water), it’s the main source of moisture variation in the process, responsible for the thermal oscillations most of the time.
In order to improve the Blast Furnace's thermal control operating system, were installed moisture analyzers in charcoal silos that operate on the microwave principle, allowing online analysis of the charcoal’s moisture percentage.
With the implementation of online charcoal moisture analyzers and integration of the data collection logic to the automation systems, including PLC, Supervisory board and Level 2 System, it was possible to obtain the automatic correction of charcoal moisture in the mass balance.
In view of this, the thermal level indicators (temperature and silicon content of hot metal) were compared to the results obtained in 2019. The average hot metal temperature had a significant reduction of 9.4 ° C, which corresponds to 2.54 kgC / t (kilo of carbon per ton of hot metal) less and the standard deviation of the silicon content in hot metal was reduced by 16.7%, indicating greater stability of the thermal level of the Blast Furnace. The silicon content out of range specified decreases by 11%. The number of charcoal moisture analyzes carried out by the laboratory has reduced 75% (from 12 to 3 analyzes in the day) and the number of mass balance updates due to moisture variation, reduced by 100% (from 12 to 0 updates on the day).
The results achieved demonstrate that the implantation of the analyzers was carried out successfully, meeting quality, health and safety standards.
