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VERSION:2.0
METHOD:PUBLISH
BEGIN:VEVENT
ORGANIZER;CN=ESTAD 2023:mailto:info@metec-estad.com
LOCATION:Room 16b
SUMMARY:A comparison of non-isothermal and isothermal hydrogen reductions of iron ore pellets based on TGA study
DESCRIPTION:Direct reduction of iron ore using hydrogen is one process that can produce iron from virgin materials and at the same time reduce CO2 emissions. In a shaft furnace, iron ore pellets are loaded at the top while hydrogen is introduced at the lower part. Pellets are slowly passing through the reactor and experience a temperature gradient ranging from low to high, i.e., non-isothermal reduction. Only a handful of studies have been performed to investigate the effect of non-isothermal reduction, and none focus on systematic analysis. Very few comparisons between isothermal and non-isothermal reductions have been made. To better understand the kinetics of non-isothermal reduction for process optimization, a preliminary study including both non-isothermal and isothermal experiments using pure hydrogen is conducted. The reduction experiments are performed in a resistance-heated furnace at 1173 K or between 723-1173 K for the isothermal and non-isothermal experiments, respectively.  Non-isothermal reduction is much slower than isothermal reduction, as expected. The heating rate greatly affects the reduction rate, increasing with increasing heating rate. The mechanisms during the isothermal and non-isothermal reductions are discussed and compared. The reduction rate slows down at the later stage of reduction. At this point, the non-isothermal reduction rate is lower compared to isothermal reduction. To further examine the effect of heating rates, the microstructure of reduced samples is studied using a scanning electron microscope. The microstructure develops over time as the pellet is reduced, this is true for both isothermal and non-isothermal reduction. The heating rates have a limited effect on the microstructure.  It would be difficult to capture and model the reduction behavior using only isothermal reduction experiments. Thus, studying non-isothermal reduction is needed. When optimizing the reduction in a shaft furnace, considerable attention should be directed toward the effect of the heating rates. 
CLASS:PUBLIC
DTSTART:20230614T094000
DTEND:20230614T100000
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