2014 Volume 54 Issue 12 Pages 2704-2712
Co-injection of two or more reducing agents via tuyères may ensure technological, economic and environmental benefits and enhance the flexibility of use of various reductants. The blast furnace technology with top gas recycling, recently tested in the scope of the ULCOS program aiming at significant mitigation of CO2 emissions, is also based on co-injection of reducing gas, pulverised coal and pure oxygen. This paper presents results of a study on conversion behaviour of pulverised coal while co-injecting further substances with focus on tuyère assembly design. Factors affecting the coal particle conversion in the raceway derived from the combustion mechanism and constructional features of tuyère stock arrangement are firstly discussed. An experimental work was performed using the Multifunctional Injection Rig for Ironmaking (MIRI) at the Department of Ferrous Metallurgy, RWTH Aachen University. Tests simulating different scenarios for injection of coal, carbon monoxide and oxygen were conducted. Conversion degree determined by three methods and microstructural analysis were used to examine the effect of pre-mixing of coal with above mentioned components on its combustion behaviour. Results obtained give hints for optimising the lance arrangement.