PROCESS constructed a detailed process simulation of an existing plant-wide vent system that included individual unit operation vent lines, vent sub-headers, vent headers, a vent blower, and a thermal oxidizer. The purpose of the simulation was to evaluate the effects of the addition of a new batch specialty organic chemical production process to the existing system. PROCESS used existing vent system drawings as well as new field sketches developed by PROCESS to build all vent system details into the simulation. New vent stream physical and chemical characterizations developed by PROCESS were used as inputs to the simulation. Using the fluid dynamics package of the process simulation software, PROCESS was able to predict vent system flow rates, velocities, and pressures at all points in the system and was thus able to pinpoint pressure bottlenecks and to formulate and demonstrate the appropriate design remedies. PROCESS was also able to evaluate the capability of the existing vent system blower to handle the new flow rates and was able to develop design and control modifications required for the blower system. In addition, the Gibbs Free Energy Reactor module was utilized to accurately model and evaluate the capacity of, and required operating conditions for the existing thermal oxidizer, and the results were used as the basis for design and control system changes for the thermal oxidizer as well. Finally, the simulation allowed PROCESS to pinpoint potential explosive limit mixtures at various points in the vent system.