(682b) Modeling and Simulation of a Piston-Type Work Exchanger for Mechanical Energy Recovery

Energy efficiency is always a focal point in achieving process sustainability. Process integration, which was initiated for thermal energy recovery through heat integration, has been very successfully practiced in the process industry. Recovery of mechanical energy, however, has not received needed attention until recently, since a concept of work integration is introduced. It is conceived that a piston-type device could be a type of equipment to perform pressure-driven work exchange; this type of unit could be called direct work exchanger (DWE). An optimally designed network system using this kind of devices should be able to systematically recover mechanical energy. Note that work exchangers have been used widely for seawater reverse osmosis (RO) desalination, where liquid streams are pressurized or depressurized. This type of unit, however, cannot be directly used for mechanical energy involving streams in gas phase in chemical process systems.

In this paper, we introduce our investigation on developing a DWE that can be operated for mechanical energy recovery involving gas streams. We have developed a CFD based model and conducted various simulations to study the design of such a device, and its operational behavior under different operating conditions. Basic design and operational optimization has been also conducted to ensure cost effectiveness and energy recovery efficiency. Case studies will demonstrate application potentials for mechanical energy recovery involving gas streams in chemical process systems.