HEAT TRANSFER IN A BITUMEN TANKER

Hi, I am a new Comsol modeler and I am trying to model a steel tanker filled with molten bitumen. The tanker is insulated and the bitumen is heated by two propane burners ( in form of U) located at the bottom. For the bitumen I have Non-isothermal Flow-Laminar , for the propane I guess Non-isothermal Flow (flow in a pipe) and also I have Heat transfer in solids for all solid structure and convection to the exterior.

I have tried many times to do my model and always I have some kind of message error.
Someone could give some directions to do this model. I am using Comsol 4.2a.

Thanks