Efficiency of Biomass Pyrolysis Product Injection into the Blast Furnace

Abstract

The biomass usage in the steel industry has benefits not only due to its “CO2 neutral carbon”, but also due to its unique chemical and physic-chemical properties. This contribution focuses on two aspects which could increase the economic efficiency of this technology. The first one is related to the thermal treatment of biomass. Woody biomass wastes were pyrolysed in a laboratory scale screw continuous reactor at different temperature profiles. Besides solid product (charcoal), yields of organic liquid and a gaseous products consisting of carbon oxides, light hydrocarbons and hydrogen were considered. The share and quality of these three fractions can be controlled by the pyrolysis parameters such as temperature, heating rate, residence time as well as presence of catalysts. The second aspect is related to the optimisation of grain size of injected solids. Different grain size fractions in the range from about 0.1 to 1.8 mm were prepared and tested using a laboratory injection rig. Furthermore, microstructure of charcoal samples were examined. Results were compared with a reference pulverised coal. It was concluded that coarser grinding of charcoal than that for coal can be sufficient for its conversion in the blast furnace raceway. The microstructure of charcoals may have a great influence on their conversion behaviour along with the chemistry. The effect of injection rate on conversion rate depends on grain size of charcoal.