(32a) A Systematic Approach for Membrane-Based Hybrid Separation Network Synthesis

Membrane separations play an indispensable role in many areas of chemical industry via facilitating (i) molecular separations (e.g., reverse osmosis), (ii) chemical transformations (e.g., membrane reactors), and (iii) enhanced mass and energy transfer between different phases through integration of hybrid separation techniques in a single unit (e.g., membrane contactors) [1-2]. Recent trends in novel process design via process intensification also highlight the importance of utilizing membrane-based separations rather than costly standalone distillation-based operations [3]. However, limited studies exist that consider the design and optimization of hybrid networks involving membrane and other separation techniques [4-6].

Recently, we have introduced a novel superstructure representation for process intensification based on building blocks [7], 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 [8] 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 [11] when the membrane-based design is optimized.

References:

[1] Drioli, E., Stankiewicz, A.I. and Macedonio, F., 2011. Membrane engineering in process intensification—An overview. Journal of Membrane Science, 380(1-2), pp.1-8.

[2] Gorak, A. and Stankiewicz, A., 2011. Intensified reaction and separation systems. Annual review of chemical and biomolecular engineering, 2, pp.431-451.

[3] 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.

[4] 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..

[5] Caballero, J.A., Grossmann, I.E., Keyvani, M. and Lenz, E.S., 2009. Design of hybrid distillation− vapor membrane separation systems. Industrial & engineering chemistry research, 48(20), pp.9151-9162.

[6] 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.

[7] Demirel, S. E., Li, J., and Hasan, M. M. F., (2017). Systematic Process Intensification using Building Blocks, Computers and Chemical Engineering, 105, 2-38.

[8] 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.

[9] Li J., Demirel S.E., Hasan M.M.F. Process Integration using Block Superstructure. Industrial & Engineering Chemistry Research, 2018, 57: 4377–4398.

[10] Li J., Demirel S.E., Hasan M.M.F. Fuel Gas Network Synthesis Using Block Superstructure. Processes. 2018, 6(3): 23.

[11] 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.