CHEMICAL ENGINEERING TRANSACTIONS VOL. 61, 2017 A publication of The Italian Association of Chemical Engineering Online at www.aidic.it/cet Guest Editors: Petar S Varbanov, Rongxin Su, Hon Loong Lam, Xia Liu, Jiří J Klemeš Copyright © 2017, AIDIC Servizi S.r.l. ISBN 978-88-95608-51-8; ISSN 2283-9216 Integration of Renewable Energy into Mass, Heat and Regeneration Network Synthesis Adeniyi J Isafiade Department of Chemical Engineering, University of Cape Town, South Africa. AJ.Isafiade@uct.ac.za This paper presents a new synthesis method for optimally integrating mass exchange networks, involving regeneration, with solar thermal energy, so as to reduce the quantity of water used in mass exchange operations, while simultaneously reducing the environmental impact associated with the use of fossil based energy sources. The problem in this paper involves gaseous streams from which ammonia has to be removed using water as the mass separating agent. The ammonia rich lean stream is then sent to a regenerator where steam stripping is used to remove the ammonia, after which the lean stream, which is now somewhat free of ammonia, is recycled back to the network of mass absorbers for further ammonia absorption from the gaseous streams. The stage-wise superstructure is adopted, however it is extended by including models to account for primary mass exchange, regeneration and heat exchange subnetworks. Other extensions include the addition of model equations to determine optimal solar panel area and heat storage vessels. The example considered demonstrates the benefits of the integrated approach. 1. Introduction The chemical process and allied industry is faced with myriad challenges among which are the need to selectively remove species from solutions, reduce emissions of pollutants (including greenhouse gases) into the environment, minimise use of energy, especially those of fossil origin, as well as minimise use of scarce natural resources such as water. The goal is to accomplish all of these in a cost effective and sustainable manner. There have been attempts to overcome these challenges, however, most of these attempts have involved tackling the aforementioned issues either individually or sequentially using methods which are heuristic based, e.g. Pinch Technology, or mathematical programming based. The paper by Liu, et al. (2013) involves the synthesis of mass exchanger networks (MENs) for multicomponent systems, however, no consideration was given to possible regeneration of the mass separating agents (MSA) or the benefits of simultaneously integrating the MEN with heat exchanger network (HEN). Isafiade and Fraser (2007) on the other hand studied MENs involving single components with the inclusion of possibilities for regeneration of the external MSA using Pinch Technology. Consideration was given to the energy associated with the regeneration process in determining the total annual cost (TAC) of the resulting network. This scenario was then extended by Isafiade and Fraser (2009a) through the use of a mathematical programming approach. Although these studies explored the benefits of combining the synthesis of heat and mass exchanger networks, however, the additional benefits that would be obtained if renewable energy, such as solar thermal, is integrated in the network, was not investigated. Recently, a host of papers presented studies involving the integration of renewable energy into process network synthesis. Such studies include the paper by Sharan and Bandyopadhyay (2015) where multiple effect evaporators were integrated with solar thermal energy, the work of Isafiade, et al. (2016) where solar thermal energy was integrated with multi-period process heat demand with opportunities for heat storage, and the paper by Nemet, et al. (2015) where solar thermal panel area as well as heat storage vessel sizes for integration with various process heat demand were targeted using a sequential technique. Other studies that also involved integration of renewable energy, in the form of solar thermal, include the paper by Atkins, et al. (2010) which also used a sequential approach for solar heat integration with a diary process heat demand, and that of Walmsley, et al. (2014) which involves integration with heat recovery loop considering both series and parallel arrangements. It is worth stating at this point that the cases where solar thermal energy has been integrated DOI: 10.3303/CET1761009 Please cite this article as: Isafiade A.J., 2017, Integration of renewable energy into mass, heat and regeneration network synthesis, Chemical Engineering Transactions, 61, 67-72 DOI:10.3303/CET1761009 67