Reliable simulation of industrial scale fermenters is a challenging problem that needs to be solved for effective operation and control of such nonlinear and complex systems. Contrary to the available studies, which mostly rely on laboratory data, this work addresses the development and test of a rigorous dynamic model incorporating two phases and transport terms for industrial fermenters used for baker’s yeast production. The influence of various parameters on model behaviour is determined by sensitivity analysis; and inspired by these results, those parameters that strongly effect the biomass production are identified by a parameter estimation technique. Comparison of the model predictions to two sets of actual process data for fed-batch and batch operating conditions verify the validity of model. The results provide valuable insights into the reliable simulation of large scale fermenters, and also bring an effective tool for further studies on optimization and control of such reactors.