In the recent years modeling was found to be beneficial for growth system design and optimization of SiC bulk crystal growth by sublimation technique. In this paper we describe a special software tool called "Virtual Reactor" (VR), which can be operated by user of the code as an actual crystal growth system, VR accounts for major specific features of sublimation growth and includes advanced models for the most important physical processes occurring in the growth system as well as the database for properties of SiC crystal and powder, graphites and thermal insulation. The software simulates global heat transfer in the whole system and inside the crucible, coupled with reactive species mass transport. Virtual characterization of the growing crystal at various stages of growth, in particular, analysis of thermo-elastic stress and dislocation density distribution is provided by VR. In this paper, we discuss basic principles of the VR operation and demonstrate some results of SiC crystal growth simulation using this software.