This paper presents the application of numerical calculation of a hybrid Euler–Lagrange approach to model the gas–solid flow combined with a combustion process in the CFB boiler that has been resolved by applying the ANSYS FLUENT 14.0. In this work, the numerical modelling of furnace processes at various speeds of airflow supply from below was estimated. For the design speed adopted values of 0.5, 1.5, 2.5 and 5 m/s. The research object is the combustion chamber of boiler unit with CFB, with steam capacity of 230 t/h.