Heat Integration in Process Water Networks

Abstract

A mathematical optimization approach for targeting the minimum utility consumption in heat-integrated process water networks is proposed in this paper. The linear programming formulations are developed for heat integration in fixed flow rate water allocation networks, for both single and multiple contaminants, incorporating isothermal mixing. Heat integration in water allocation networks is also addressed through nonisothermal mixing of streams, and this is formulated as a discontinuous nonlinear programming problem. Utility requirements, for isothermal as well as for nonisothermal mixing, are compared over a range of minimum approach temperatures to evaluate the energy performance using illustrative examples. The number of required heat exchangers is less in heat-integrated water allocation problems with nonisothermal mixing. Simultaneous optimization of the overall heat-integrated water allocation network, to minimize the operating cost, is also formulated and solved.

Water and energy integration: A comprehensive literature review of non-isothermal water network synthesis

“…However, the sequential approaches are used in these studies producing again sub-optimal solutions. Several papers have addressed energy optimisation within WNs , 2011George et al, 2011;Bandyopadhyay and Sahu, 2011) by considering isothermal and non-isothermal mixing. On the basis of sourcedemand network representation an energy recovery algorithm (ERA) was presented through a tableau-based procedure .…”

“…It is found that utility consumption of the studied cases considering non-isothermal mixing is always less than or equal to the utility consumption in the isothermal mixing cases. Finally, it should be highlighted that the sequential optimisation approach has been used in the studies , 2011George et al, 2011;Bandyopadhyay and Sahu, 2011) for the overall synthesis WN-HEN problem and the obtained results are sub-optimal because trade-offs between freshwater usage, utility consumption and investment cost are not considered simultaneously.…”

Synthesis of Heat-Integrated Resource Conservation Networks

“…Sequential linear programming models have been developed to first determine the minimum fresh water consumption followed by minimum energy requirement (Bagajewicz et al, 2002;Feng et al, 2009;George et al, 2011;Sahu and Bandyopadhyay, 2012). Detailed heat integrated water network (HIWN) is then identified via MINLP models (Bagajewicz et al, 2002;Feng et al, 2009;George et al, 2011;Sahu and Bandyopadhyay, 2012).…”

“…Case study 3 reports a single property-based water network adopted from George et al (2011). It consists of three process sinks and three process sources, with acetone and water in the process streams.…”

Simultaneous heat integrated resource allocation network targeting for total annual cost considering non-isothermal mixing

“…George et al (2011) introduced a discontinuous non-linear programming (DNLP) model to optimize the total operating costs of the HIRAN, taking into account non-isothermal mixing. Tan et al (2014b) proposed a MINLP formulation based on the floating pinch concept (Tan et al, 2014a) to design a HIRAN with minimum operating costs, for multiple contaminants and considering other properties than the composition or temperature, such as pH or density.…”