CFD Study on the Heavy Oil Lance Positioning in the Blast Furnace Tuyere to Improve Combustion

Abstract

Auxiliary fuels are used to replace expensive coke in two ways, as a reducing agent for iron oxides and to provide energy for the blast furnace operation. Poor combustion of heavy oil produces soot and cenosphere, which plug the coke bed and lead to an increased pressure drop and lower the productivity of blast furnace. In the study a new combustion model for heavy oil in a blast furnace is explained. Droplet atomization is modelled with the wave breakup model and the combustion consists of droplet vaporization and gas phase combustion with a detailed combustion model. Three different lance positions were modelled to evaluate the effect of lance position on combustion and blast furnace operation. The study is limited to the tuyere-raceway area, where e.g. mixing between air blast and heavy oil, pressure drop and combustion have been investigated. The most promising position based on this study is to move the injection lance 10 cm downstream from the tuyere nose. The results show that the pressure drop increases when the lance is moved inside the tuyere, but the pressure drop growth is moderate until the lance is at least 10 cm downstream from the tuyere nose. According to the results the pressure drop versus lance position behavior is similar to an experimental study previously described in the literature. In addition the combustion behavior was found to be similar to the actual blast furnace.