Design of heat exchanger networks and control structures for natural gas expander plant

Abstract

Energy recovery by heat exchanger network (HEN) is the important stage in chemical process. The energy integration causes to the interactions and may cause the process more difficult to control. Therefore, in order to achieve maximum energy recovery and keep target value at their desirable value, the resilient heat exchanger networks that can tolerate variations are important. Furthermore, the plantwide control strategies of the process should be considered. In this research, nine alternatives (8 new alternative designs and base case) of heat exchanger networks and three control structure designs of the natural gas expander plant are proposed. The resilient heat exchanger networks are designed using the disturbance load propagation method (Wongsri, 1990) and the control structures of HENs using the heat pathway heuristics (Wongsri and Hermawan, 2005). The plantwide control structures are designed by using Luyben heuristic design method (1999) for the CS1 control structure and Fixture point theorem (Wongsri, 2008) for the CS2 and CS3 control structure. The result shows the CS3 control structure can reject disturbances better than other control structures. The designed control structure is evaluated based on the rigorous dynamic simulation using the commercial software HYSYS