(32a) A Systematic Approach for Membrane-Based Hybrid Separation Network Synthesis
Recently, we have introduced a novel superstructure representation for process intensification based on building blocks , which has been demonstrated for automatic identification of novel process alternatives including membrane reactors, reactive distillation, etc. The block-based representation is also applied for process synthesis  and integration [9-10]. The proposed superstructure is a collection of blocks positioned on a two-dimensional grid which can be used to represent several physical and chemical phenomena. The search for optimal processing routes is automated via a mixed integer nonlinear programming (MINLP) formulation. In this work, we use the building block representation for design and synthesis of hybrid separation networks. We represent each membrane module as a collection of neighboring blocks separated by a membrane boundary. Similarly, vapor-liquid contact is represented as two neighboring blocks sharing a common boundary for phase contact and transition which constitutes a tray for a distillation operation. The material flow in the superstructure is achieved through inter-block material streams that connect different blocks, e.g., membrane and vapor-liquid contact modules, with each other. Systematic arrangement of the building blocks in a grid formation paves the way for the representation of different membrane flow patterns, i.e. cross-flow, counter-current, co-current, and different recycle alternatives between separation unit alternatives.
The proposed method is generic in the sense that it has the potential for designing separation systems involving membranes, distillation and/or membrane distillation. We will present one such case study on H2/CO separation that resulted in more than 40% decrease in the total annual cost compared to the base-case design reported in the literature  when the membrane-based design is optimized.
 Drioli, E., Stankiewicz, A.I. and Macedonio, F., 2011. Membrane engineering in process intensificationâAn overview. Journal of Membrane Science, 380(1-2), pp.1-8.
 Gorak, A. and Stankiewicz, A., 2011. Intensified reaction and separation systems. Annual review of chemical and biomolecular engineering, 2, pp.431-451.
 Tian, Y., Demirel, S. E., Hasan, M. M. F., Pistikopoulos, E. N. An Overview of Process Systems Engineering Approaches for Process Intensification: State of the Art. Chemical Engineering and Processing: Process Intensification, Submitted.
 Marquardt, W., Kossack, S. and Kraemer, K., 2008. A framework for the systematic design of hybrid separation processes. Chinese Journal of Chemical Engineering, 16(3), pp.333-342..
 Caballero, J.A., Grossmann, I.E., Keyvani, M. and Lenz, E.S., 2009. Design of hybrid distillationâ vapor membrane separation systems. Industrial & engineering chemistry research, 48(20), pp.9151-9162.
 Tula, A.K., Befort, B., Garg, N., Camarda, K.V. and Gani, R., 2017. Sustainable process design & analysis of hybrid separations. Computers & Chemical Engineering, 105, pp.96-104.
 Demirel, S. E., Li, J., and Hasan, M. M. F., (2017). Systematic Process Intensification using Building Blocks, Computers and Chemical Engineering, 105, 2-38.
 Li, J.; Demirel, S.E.; Hasan, M.M.F. Process Synthesis using Block Superstructure with Automated Flowsheet Generation and Optimization. AIChE Journal, 2018, under review.
 Li J., Demirel S.E., Hasan M.M.F. Process Integration using Block Superstructure. Industrial & Engineering Chemistry Research, 2018, 57: 4377â4398.
 Li J., Demirel S.E., Hasan M.M.F. Fuel Gas Network Synthesis Using Block Superstructure. Processes. 2018, 6(3): 23.
 Uppaluri, R.V., Linke, P. and Kokossis, A.C., 2004. Synthesis and optimization of gas permeation membrane networks. Industrial & engineering chemistry research, 43(15), pp.4305-4322.