Thesis (M.Eng.)--Chulalongkorn University, 2009

For industries, material and energy recycle are beneficial in economic aspect. However, they make processes more complex. So the good control structure is necessary and is the important thing in order to maintain process operation, safety and product quality. In this research, control structures for phenol hydrogenation to cyclohexanone process consisting of many recycle streams and energy integration is designed. Procedure of Luyben (1998) and procedure of Wongsri (2009) are applied in design. This study use software HYSYS to simulate phenol hydrogenation to cyclohexanone process at steady state and dynamic. Designed control structures using procedure of Luyben (1998) and designed control structures using procedure of Wongsri (2009) can also design the same control structures. The four control structures are designed by using these two procedures. Then all designed control structures are evaluated the dynamics performance and are compared with each others. The result shows that all designed control structures can eliminate disturbances, can maintain product quality and can achieve process constraints. In sum, the plantwide control procedure of Wongsri (2009) can design the good performance control system.