(659b) An Integrated Set of Methods, Algorithms and Software Components for Sustainable Process Design

Population on earth is estimated to increase to around 10.5 billion by 2050. Consequently, the global GPD will need to increase with resulting increases in demands on supply of energy and water, resulting in greater need for control of global warming and climate change [1]. Sustainable process design relates to chemical and/or biochemical processes that include sustainability criteria as constraints that must be satisfied together with economic feasibility, safe operability and efficient use of resources [2]. There are many ways to achieve sustainable process designs. The 3-stages method and associated computer-aided tools is one such alternative [3], where, in the first stage, the synthesis problem is solved to obtain a feasible processing route; in the second stage the design details are added so that economic, sustainability, etc. analysis can be performed to identify process “hot-spots” where the process design needs to be improved; the final third stage is to identify alternatives to improve the design from stage 2 to make it more sustainable and thereby acceptable. This 3-stages method can be applied for new processes as well as to retrofitting already existing processes. As the need to tackle the effects of global warming and climate change is urgent, in this presentation, the application of sustainable process design to retrofit existing designs to more sustainable designs will be highlighted. More specifically, energy intensive process operations that can be retrofitted to significantly reduce their energy demands through a combination of energy integration, hybrid separation and process intensification, will be highlighted. The specific software tools and associated methods have been reported earlier, however this presentation focuses on their integration, which is needed for performing sustainable process design, updated versions of methods and algorithms, and the case studies highlighting their applications. The objective in every case is first to identify the operation(s) that have the largest energy demands and then to find alternatives that reduce energy (and other utilities) demands without affecting the product specifications and improving environmental impacts and the economics such that the additional costs can be paid back in a short time through increased profits. That is, find more sustainable alternative designs.

As most existing chemical processes still employ distillation as the means for many of the required separation tasks, they are also the operations that have higher energy demands than others and therefore, can be targeted for improvements through hybrid separation schemes [4] in addition to other options such as simultaneous process optimization and heat integration [5] and/or process intensification [6]. Options, such as reduction (elimination) of the release of hazardous chemicals through purge streams, reduction of compressor costs in recycle streams, etc., can also be included in the evaluations to identify and evaluate the more sustainable alternatives. The ProCAFD software tool, which is based on the 3-stages method, is used together with well-known commercial simulators and new additional user-modules to perform the sustainable retrofit designs. Results from case studies employing ProCAFD together with the associated tools will be presented, highlighting also the data-flow needed for the work-flow related to the various problem solutions.

References:

1. E. N. Pistikopoulos, A. Barbosa-Povoa, J. H. Lee, R. Misener, A. Mitsos, G. V. Reklaitis, V. Venkatasubramanian, F. You, R. Gani, 2021, Process Systems Engineering–The Generation Next?, Computers & Chemical Engineering, 147, 107252.
2. M. Martin, R. Gani, I. M. Mujtaba, 2022, Sustainable process synthesis, design and analysis: Challenges and opportunities, Sustainable Production & Consumption, 30, 686-705
3. A. K. Tula, M. R. Eden, R. Gani, 2019, Hybrid method and associated tools for synthesis of sustainable process flowsheets, Computers & Chemical Engineering, 131, 106572
4. J. P O'Connell, M. R. Eden, A. K. Tula, R. Gani, 2019, Retrofitting Distillation Columns with Membranes, Chemical Engineering Progress, 115 (12), 41-49
5. M. A. Duran, I. E. Grossmann, Simultaneous optimization and heat integration of chemical processes, 1986, AIChE J, 32, 123-138
6. A. K. Tula, M.R. Eden, R.Gani, 2020, Computer-aided process intensification: Challenges, trends and opportunities, AIChE Journal, 66, e16819