In this paper the multiphase transient multi-dimensional mathematical model of the blast furnace is applied to analyze small coke based compact blast furnace process operating with hydrogen injection into a second level of tuyeres. The hydrogen injection into the shaft of the furnace drastically modify in furnace conditions and only comprehensive models can accurately estimate the effective inner conditions and stability of the process. The model is based on transport equations of momentum, energy and chemical species describing a five phase system coupled with additional relations for interphase momentum, heat and chemical reactions rates. The set of differential equations are iteratively solved based on the finite volume method discretization procedure for a general coordinate system. Four cases of stable all pellets operations are studied: I) Base case with small coke and 100 kg/t of PCI; Ii) 10% of the reducing gas replaced by H2 at the second level of raceway; Iii) 20 % of the reducing gas replaced by H2 and iv) 30% of the reducing gas replaced by H2. Under the above simulation conditions, it was found out that is possible to enhance the furnace performance and decrease the specific emissions of CO/CO2. The results indicated that high amount of reducing gas replacement by H2 is possible if fine adjustments of the blast conditions is carried out. In this investigation was found that up to 50% of the replacement is feasible with smooth operation, in contrast, higher amount presented unstable operation mainly due to deterioration of the inner gas thermo physical properties which strongly affects the rates of heat and chemical reactions in the shaft region
Keywords: Modeling, Hydrogen reduction, Biomass