Modelling of gas and char flows at high PCI through experimental and theoretical studies of the raceway and the dead man : final report

The project consists of four main parts performed by different research centres : study of blast furnace dead man at high PCI (CSM) ; experimental studies on raceway dimensions and gas circulation in relation to the combustion of injected coal (CENIM and Aceralia) ; further productivity increase by injection of metallized ore fines at high PCI (RWTH Aachen) ; modelling of gas and char flows at high PCI (CRM). Several mathematical models of dead man have been developed using both traditional and non-traditional methods. Only two models were sufficiently reliable for the simulation of the whole blast furnace burden descent in terms of descent velocity, stress field and material segregation. Experimental work provided information for the set-up of the models. The experimental studies of the raceway have been carried out in two methacrylate models, where ice cubes are melted by warm air, and in a coke gasification chamber placed on a weighing platform. A georadar has been used to explore the inside of the chamber. These models helped to understand the physics of blast furnace raceways. A coal-based metallisation process for iron ore fines has been designed for sticking-free operations ; its technical and economic potential have been assessed. Consumption figures and production costs are in the range of available figures for existing direct reduction plants. The simulated injection of metallised fines into the blast furnace or the charging of briquetted metallised material from the top leads to noticeable increases of productivity at slightly reduced costs. CRM developed a mathematical model simulating the main phenomena of the blast furnace. It has been calibrated by vertical probings and by gas tracings. The model shows the strong influence of the burden distribution pattern on the gas distribution and on the different operating results. Simulations of coal rate increase revealed no significant modification of the gas distribution. A comparison is made with industrial results reported in literature.