Wet-recycle oxy-fuel (O2/CO2/H2O) fluidized bed (FB) combustion shows high efficiency of the power plant and low emission of pollutants. In O2/CO2/H2O atmosphere

char-O2

char-CO2 and char-H2O reactions can occur at the same time. To reveal the mechanism of interaction among those reactions

macro-thermogravimetric analysis (TGA) experiments were carried out in mixture of O2

CO2 and H2O at temperature of 900℃ using a bituminous coal-char. The reaction kinetics of char-O2

char-CO2 and char-H2O reactions were obtained through Langmuir-Hinshelwood (LH) model fitting. Assumptions of separate active sites and common active sites were used to analyze the experimental data in O2/CO2

O2/H2O and CO2/H2O atmospheres

results show that H2O molecules have priority in taking active sites

following by O2

and finally is CO2. In O2/CO2/H2O atmosphere

partial competition among char-O2

char-CO2 and char-H2O reactions was experimentally observed

and neither conventional separate active sites nor common active sites models could describe the reaction rate of bituminous char. According to the theory of H2O molecules primarily and O2 molecules sub-primarily occupy active sites when O2

CO2 and H2O are present

a new L-H type model was built. The developed model was found to describe well with the measured reaction rate of bituminous char in mixture of O2

CO2

and H2O. The results of this work provide theoretical basis for analyzing of the oxy-fuel FB combustion characteristics of char and developing of reliable char combustion model.