Present work generalizes the model [1] of chemical condensation for reacting flow in a tube. The problem is considered using a simultaneous description of process both on the microscale (for a single particle) and macroscale (for the averaged two-phase gasdynamics). By using the heat-mass transfer and chemical kinetics splitting, a new technique is developed [2,3] in order to provide the numerical simulation of a reacting two-phase flow in a tube. This approach enables to control the scales interaction and justify various flow structures of the phase transition.