CHEMICAL ENGINEERING TRANSACTIONS VOL. 35, 2013 A publication of The Italian Association of Chemical Engineering www.aidic.it/cet Guest Editors: Petar Varbanov, Jiří Klemeš, Panos Seferlis, Athanasios I. Papadopoulos, Spyros Voutetakis Copyright © 2013, AIDIC Servizi S.r.l., ISBN 978-88-95608-26-6; ISSN 1974-9791 Process Modification Potentials for Total Site Heat Integration Kew Hong Chew a , Sharifah Rafidah Wan Alwi a, *, Jiří Jaromír Klemeš b , Zainuddin Abdul Manan a a Process Systems Engineering Centre (PROSPECT), Faculty of Chemical Engineering, Univerisiti Teknologi Malaysia, 81310 UTM Johor Baru, Johor, Malaysia b Centre for Process Integration and Intensification – CPI 2 , Research Institute of Chemical and Process Engineering - MŰKKI, Faculty of Information Technology, University of Pannonia, Egyetem u. 10, H-8200 Veszprém, Hungary shasha@cheme.utm.my The technique to identify the scope for process modifications to improve energy efficiency of individual processes using the Composite Curves was developed many years ago. The potential of improving Total Site Heat Integration (TSHI) via process modification based on the Plus-Minus Principles of Pinch Analysis has been analysed in this work. An approach to target process modifications to maximise energy saving via TSHI has been proposed. The approach consists of two steps: in the first step, the options for reducing utility targets are identified by the use of Total Site Profiles (TSP) and Site Composite Curves (SCC); the second step is to link the identified changes on the TSP/SCC to the specific changes required at the individual processes. The study has shown that the Plus-Minus Principles can be applied on a TS context. By targeting the process modifications at the selected process sections, an improvement in heat recovery can be achieved. 1. Introduction Process modification strategies to improve the Heat Integration (HI) of single processes based on the shape of Composite Curves (CC) and the Grand Composite Curve (GCC) were developed by Linnhoff and Vredeveld (1984). Some established rules for process modifications using the CC and GCC include the Plus-Minus Principles, Keep Hot Streams Hot and (KHSH) Keep Cold Streams Cold (KCSC) as well as the appropriate placement of utilities. Exploiting and optimising the process soft data, use of the appropriate minimum approach temperature (∆Tmin) and suitable application of insulations above and below the pinch can be effective in improving heat recovery. The concept of Total Site (TS) was introduced by Dhole and Linnhoff (1993). Klemeš et al. (1997) established the Total Site Profiles (TSP) to represent the thermal profile of TS and the Site Composite Curves (SCC) to represent the site utility systems for utility targeting. The SCC comprises of Hot and Cold Utility Composite Curves. The Site Pinch (SP) is where the two utility CC overlaps. The Utility Grand Composite Curve (UGCC) provides a visual summary of the external utility requirement. For retrofit cases, the TSP can be constructed from the heating and cooling requirements of each process. The Plus-Minus Principles has not been used together with the TSP to identify the scope for process modifications to improve TSHI. Hackl et al. (2011) showed that TSP and SCC can be used to identify potential changes to the utility systems to reduce the overall site heating and cooling requirements. Replacing the low pressure steam (LPS) heating with hot water (generated from Site Source) changed the shape of the SCC (the Cold Utility CC in this case) and resulted in the shifting of the SP. This increases the overlap of the Site Source and Sink Profiles and increases the heat recovery. Nemet et al. (2012) demonstrated the use of Plus-Minus principle on TS to develop the strategies to plan the extension of an existing site. The Plus-Minus principle, together with the Process Utility Matrix, is used to evaluate the benefit of integrating a new process to existing TS. In this study, the Plus-Minus principle of process modifications is used to further improve HI, and hence the utility targets of a TS. DOI: 10.3303/CET1335029 Please cite this article as: Chew K.H., Wan Alwi S.R., Klemes J.J., Manan Z.A., 2013, Process modification potentials for total site heat integration, Chemical Engineering Transactions, 35, 175-180 DOI:10.3303/CET1335029 175