The extended use of the He tracing technique and the assessment of the blast furnace shaft permeability

In the frame of this project two types of measurements were performed. While CRM, SIDMAR and CORUS focused on doing only transfer time measurements in order to characterise the radial gas distribution, ARCELOR RESEARCH, TKS and ACERALIA performed also concentration measurements aiming at detecting cross-flows and at assessing the BF shaft permeability. Both types of measurements seem to be able to give valuable information regarding the gas distribution of the furnace and could be complementary to each other. Helium tracing was developed as a more reliable tool for monitoring the gas distribution in a blast furnace, enabling to make gas transfer time measurements more continuously available. However, helium tracing was not the tool we expected. As lots of BF measurements helium tracing is not a sufficient tool to monitor the gas distribution in the blast furnace, giving all the information needed by the operator with a sufficient reliability and accuracy. It has to be regarded as a supplementary tool. Lack of consistency of the measurements makes that an advisory tool could not be well developed, so the assessment of the BF shaft permeability is rather poor / difficult. Making use of the He tracing measurements requires a long-term investigation. Several R&D techniques were also developed during this project: tuyere injection with uptake detection to look for gas distribution asymmetries, two tracing gases technique (TTGT), gas injection at different tuyeres, shaft injection and tuyere probe injection. All these techniques seem to give valuable information but to understand their significance fully more research is needed