(203ab) A Multi-Scale Framework for Enterprise-Wide Design and Retrofit of Processing Networks: From Meso- to Mega-Scale

A multi-scale framework for enterprise-wide design and retrofit of processing networks: from meso- to mega-scale

A. Quaglia, G. Sin,* R. Gani

CAPEC, Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark; email: aq@kt.dtu.dk. *email:gsi@kt.dtu.dk.

Large multinational processing companies operate several chemical processes in a coordinated manner, resulting in complex processing networks, through which the transformation of a range of raw materials into a range of products is realized. Because of the dynamic changes occurring in the business environment, the structure of these processing networks is constantly modified, to expand or reduce production capacity, adapt to new production, adopt new process technologies, etc (Kurkkio et al. 2011).

The problem of optimal design, retrofit and operation of processing networks is a complex multi-scale problem, spanning from meso- to mega-scale. While the design decisions are often taken at the unit-operation and flowsheet level (meso-scale), the considerations on which these decisions are taken are in fact related to higher scales, having to reflect the integration of the different processes at plant level (with respect to production capacity, utilities avalilability, logistics, etc.) as well as the overall enterprise (with respect to business optimization, management of resources and cash flows, etc.).

Because of the interdependencies between the different scales, the design of this expansion or retrofit of processing networks is a complicate and delicate decision-making activity, which has a large impact on the profitability of the company; therefore a large amount of time and resources is dedicated to it (Grossmann, 2005).

In an earlier work, we developed an integrated business and engineering framework for the synthesis and optimization-based design of processing networks, in which the process- and plant-scale were captured (Quaglia et al., 2012). In this contribution, we propose an expansion of the framework, through the inclusion of the mega-scale. With this expansion, the multi-scale complexity of the enterprise is represented as a network-of-networks. Within this representation, the enterprise is modeled as a network of processing networks, each of them constituted by a network of processing plants, constituted by a sequence of one or more processes.

The proposed multi-scale representation allows capturing the interdependencies between scales in an explicit manner, and therefore including them in the optimization-based design. Within the framework, the increased complexity associated to the consideration of the mega-scale is managed through a systematic approach, based on the use of generic models in order to facilitate the task of data management, and on the integration of state-of-art solution methods and algorithms.

The features of the expanded business and engineering framework are highlighted through the solution of a case study. In the case study, a generic process model structure is adopted to map the business of a company operating several processing networks, through the development of a network-of-networks model.

The model is used to evaluate the consequences of changes in the business environment (with respect to market conditions, raw material availability and regulations) on the performances of the overall company. Then, a number of potential expansion and retrofit actions are generated and represented by means of a superstructure, resulting in a large scale MINLP problem. The problem is solved, in order to determine the optimal retrofit, from an enterprise-wide perspective.

 References

M.Kurkkio, J.Frishammar, U. Lichtenthaler, 2011. Where process development begins: A multiple case study of front end activities in process firms.Technovation (31) 490-504.

I.E. Grossmann, 2005, Enterprise-wide Optimization: A New Frontier in Process Systems Engineering, AIChE Journal (51) 1846-1857.

A.Quaglia, B.Sarup, G.Sin, R.Gani, 2012, Integrated business and engineering framework for synthesis and design of enterprise-wide processing networks, Computers & Chemical Engineering (38) 213-223.