Please mention the desired top and bottom compositions that is expected from the distillation column output.
Methanol-Acetonitrile-Benzene forms a very complex ternary azeotropic system and therefore cannot be separated by conventional distillation. It has to be separated by pressure swing distillation. Kindly refer to the DWSIM flowsheeting Completed Flowsheets. You can find the flowsheet to solve Methanol-Acetonitrile-Benzene here.