In this study a model was derived to describe the polymer devolatilization in a purge column. The model is based on a material balance and utilizes a finite difference method to calculate the devolatilization of spherical particles. A user friendly Excel to FORTRAN interface was programmed, which permits the user to enter all parameters within Excel and receive the calculation results automatically in Excel. A lock hopper sequencing was successfully incorporated to simulate the removal of devolatilized polymer at the bottom of the column and addition of fresh wet polymer at the top. Furthermore, the program calculates the vent gas concentration which is needed for optimization of the vent gas treatment. Purge experiments were conducted to verify the model.