Solution Strategies for the Synthesis of Heat-integrated Process Water Networks

This contribution describes the use of sequential and simultaneous strategies for the synthesis of heatintegrated process water networks (HIPWNs). The former strategy consists of the water network (WN) model by Ahmetovic and Grossmann (2011) , which determines the minimum freshwater consumption and the stage-wise model by Yee et al. (1990) for the synthesis of a heat exchanger network (HEN), both of which are performed sequentially. In the recently introduced approach by Ahmetovic and Kravanja (2012) both networks are solved simultaneously by applying a combined (WN-HEN) model. This combined model is formulated as a non-convex mixed integer nonlinear programming (MINLP) problem with the objective function defined as the total annual cost (TAC). As, on the one hand, the combined model in this simultaneous approach enables the obtaining of appropriate trade-offs between freshwater, utilities, and investment, it is, on the other hand, very difficult to solve, due to its nonconvex and nonlinear nature. The synthesis of HIPWNs thus still remains a big challenge. The development of efficient solution strategies is necessary in order to accomplish this task. In this paper, syntheses of HIPWNs are carried out using the above-mentioned strategies. It is worth pointing out, that in the simultaneous approach the problem can be solved directly as one system or the WN solved first to provide a good initial point followed by the overall heat-integrated process water network (HIPWN) problem after. The proposed strategies were tested on a literature Case-Study. The solutions were obtained with the minimum consumption of freshwater and utilities, and TAC was significantly improved, when compared to those reported in the literature. The solutions obtained clearly indicate that the proposed strategies can be successfully applied for the synthesis of HIPWNs.

[1]  Robin Smith,et al.  Studies on simultaneous energy and water minimisation - Part II: Systems with maximum re-use of water , 2005 .

[2]  Jin-Kuk Kim,et al.  Improving energy recovery for water minimisation , 2009 .

[3]  Miguel J. Bagajewicz,et al.  Synthesis of non-isothermal heat integrated water networks in chemical processes , 2008, Comput. Chem. Eng..

[4]  Robin Smith,et al.  Studies on simultaneous energy and water minimisation—Part I: Systems with no water re-use , 2005 .

[5]  G. T. Polley,et al.  Design of water and heat recovery networks for the simultaneous minimisation of water and energy consumption , 2010 .

[6]  Ignacio E. Grossmann,et al.  Global superstructure optimization for the design of integrated process water networks , 2011 .

[7]  Jin-Kuk Kim,et al.  Synthesis and optimisation of heat-integrated multiple-contaminant water systems , 2008 .

[8]  Junghwan Kim,et al.  A simultaneous optimization approach for the design of wastewater and heat exchange networks based on cost estimation. , 2009 .

[9]  Miguel J. Bagajewicz,et al.  Energy efficient water utilization systems in process plants , 2002 .

[10]  Gang Rong,et al.  Systematic Optimization of Heat-Integrated Water Allocation Networks , 2011 .

[11]  Chih-Yao Lin,et al.  Simultaneous optimal integration of water utilization and heat exchange networks using holistic mathematical programming , 2009 .

[12]  Ignacio E. Grossmann,et al.  Simultaneous optimization models for heat integration. III, Process and heat exchanger network optimization , 1990 .

[13]  Cheng-Liang Chen,et al.  Synthesis of heat-integrated water-using networks in process plants , 2010 .

[14]  Jacek Jez.  Review of Water Network Design Methods with Literature Annotations , 2012 .

[15]  Yongrong Yang,et al.  Design Energy Efficient Water Utilization Systems Allowing Operation Split , 2008 .

[16]  Kevin C. Furman,et al.  A Critical Review and Annotated Bibliography for Heat Exchanger Network Synthesis in the 20th Century , 2002 .

[17]  Ignacio E. Grossmann,et al.  Systematic Methods of Chemical Process Design , 1997 .

[18]  Xiao Feng,et al.  A new approach to design energy efficient water allocation networks , 2009 .

[19]  Miguel J. Bagajewicz,et al.  A review of recent design procedures for water networks in refineries and process plants , 2000 .

[20]  Bodo Linnhoff,et al.  A User guide on process integration for the efficient use of energy , 1994 .

[21]  Zdravko Kravanja,et al.  Simultaneous synthesis of process water and heat exchanger networks , 2013 .

[22]  Igor Bulatov,et al.  Sustainability in the Process Industry: Integration and Optimization , 2010 .

[23]  Mahmoud M. El-Halwagi,et al.  Sustainable Design Through Process Integration: Fundamentals and Applications to Industrial Pollution Prevention, Resource Conservation, and Profitability Enhancement , 2011 .

[24]  Robin Smith,et al.  Chemical Process: Design and Integration , 2005 .

[25]  Ian C. Kemp,et al.  Pinch Analysis and Process Integration: A User Guide on Process Integration for the Efficient Use of Energy , 2007 .

[26]  Chih-Yao Lin,et al.  Simultaneous optimization approach for integrated water-allocation and heat-exchange networks , 2008 .