(537g) Simultaneous Process Synthesis and Heat Integration Using Building Block Superstructure

Efficient energy utilization is a paramount factor for the profitability and sustainability of a chemical plant as cost of the end-product and environmental impact of the process is highly dependent on the energy consumption of the process. Hence, the degree of heat integration within the process is an important decision that has to be handled together with the synthesis and design of the process. Currently, there are several methods available in the literature for the simultaneous process synthesis and heat integration [2-6]. These methods are mainly demonstrated for the classic superstructure representations which are based on pre-specified equipment types and priori postulated flowsheet connectivity.

Building-block based superstructure [7], on the other hand, can yield non-intuitive flowsheets while considering different mass integration alternatives without a priori postulation of the processing steps and the connectivity between them. This representation is based on a two-dimensional grid structure where several different phenomena, e.g. reaction, V-L equilibrium, G-L equilibrium, etc., can be represented either as a ‘single block’ or via multiple neighboring blocks sharing a common boundary. This provides a generic representation method for novel intensified equipment design and synthesis. Recently, this method has been also demonstrated for equipment-based representation along with detailed design formulations [8]. Furthermore, the method has been applied for different process integration problems including mass integration, heat integration and property integration [9-10]. In this work, we will show that the building block representation method can be also used to perform simultaneous flowsheet synthesis and heat integration. The formulation is based on a single mixed integer nonlinear programming (MINLP) model. As the flowsheet connectivity and equipment types are not specified a priori, the heat integration formulation is based on a generic formulation that can handle streams with unknown identity (i.e. hot/cold). Owing to its fundamental outlook toward process synthesis, building-block superstructure with heat integration enables to design, synthesize and discover new processes including refrigeration cycles without specification of the processing routes beforehand. With this, proposed method becomes a powerful tool for the synthesis of more sustainable and energy efficient processes for a variety of applications which will be demonstrated by several case studies.

References:

[1] Chen, Q. and Grossman, I.E., 2017. Recent Developments and Challenges in Optimization-Based Process Synthesis. Annual Review of Chemical and Biomolecular Engineering, 8(1).

[2] Papoulias, S.A. and Grossmann, I.E., 1983. A structural optimization approach in process synthesis—III: total processing systems. Computers & chemical engineering, 7(6), pp.723-734.

[3] Duran, M.A. and Grossmann, I.E., 1986. Simultaneous optimization and heat integration of chemical processes. AIChE Journal, 32(1), pp.123-138.

[4] Yee, T.F. and Grossmann, I.E., 1990. Simultaneous optimization models for heat integration—III. Process and heat exchanger network optimization. Computers & Chemical Engineering, 14(10), pp.1165-1184.

[5] Grossmann, I.E., Yeomans, H. and Kravanja, Z., 1998. A rigorous disjunctive optimization model for simultaneous flowsheet optimization and heat integration. Computers & chemical engineering, 22, pp.S157-S164.

[6] Kong, L., Avadiappan, V., Huang, K. and Maravelias, C.T., 2017. Simultaneous chemical process synthesis and heat integration with unclassified hot/cold process streams. Computers & Chemical Engineering, 101, pp.210-225.

[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.