Performance evaluation of heat integrated and control structures of butane isomerization plant

Abstract

In this work, three new heat exchanger networks (RHEN5-7) are designed to reduce energy consumption for Butane Isomerization plant. The resilient heat exchanger networks design follows Wongsri’s resilient HEN synthesis method (1990). These structures has 1 feed effluent heat exchanger (FEHE) instead of 2 FEHEs as in the previous four RHEN designs (Kunajitpimol, 2006). The seven RHENs and the base case (Luyben, 1998) are evaluate dynamically using HYSYS. The energy saving ranges from 16.36-25.24% compared to the base case. The new control structures (CS5-CS8) together with Luyben’s (CS1-CS2) and Kunajitpimol’s (CS3-CS4) are implemented on the eight heat integrated process structures (HIPs). Two kinds of disturbances are used to evaluate control structure performances: thermal disturbance (transformed into composition disturbance after leaving the reactor) and the material flow disturbance. We found that the control structure CS3 and CS7 are the best control performance with all HIPs for thermal disturbance. The control structures CS1 and CS5 with HIP3, HIP4, HIP6 and HIP7 are the best control performance for material recycle flowrate disturbance. We can conclude that the closed-to-realistic performance evaluation is necessary to choose the suitable heat integrated structure and proper control structure. This can be done in real time domain using rigorous process dynamic simulator like HYSYS.