Water network design

Decision variables and all other constraints are the same as those in the MOO problem. The SOO problem is a MINLP problem this problem for water network design (Section 12.5.1) has 396 continuous variables, 182 integer variables and 586 constraints. Its solution for one value of e gives one Pareto-optimal (non-dominated) solution, and so the SOO problem has to be solved for different values of e to find many Pareto-optimal solutions, as discussed in Chapter 4. 

Total Flow Rate through Regeneration Units (t/h) 

The total cost of each Pareto-optimal water network is also reported in Table 12.2. However, this cannot be the only basis for selecting a particular water network design, as preferences of the decision maker, such as number of interconnections, are important and costs depend on plant location and time. This is illustrated in Table 12.2 using two different fresh water costs (1.0 and 0.38 /t) and two different AF for capital cost (0.1 and 0.2). 

---

Figure 24.20 Cooling water network design with target return temperature of 55°C. (From Kim J-K and Smith R, 2001, Chem Eng Sci, 56 3641, reproduced by permission of Elsevier Ltd.)...

This simple example illustrates the basic principles of water network design for maximum reuse for a single contaminant. A number of issues need to be considered that would apply to more complex examples. Consider Figure 26.25 involving three water mains and three operations. Operation 2 above the pinch terminates at a concentration less than the concentration for the high concentration water main. The outlet of Operation 2 must not be fed directly into this final water main. The basis of the mass balance from Figure 26.17 dictates that all streams must achieve the concentration of the water mains into... 

Figure 26.36 Water network design based on the optimization...

Poplewski, G., Jerowski, J.M., Jerowska, A. Water network design with stochastic optimization approach. Chem. Eng. Res. Des. 89, 2085-2101 (2011)... 

Table 12.2 Important design and operating data for water network designs (that is, non-dominated solutions in Figure 12.2). 

Figure 12.7 Simultaneous minimization of fresh water flow rate and total flow rate through regeneration units, for water network design/revamping for different limits on contaminant concentrations in waste water (CC in WW).

Boix, M., Montastruc, L., Pibouleau, L. et al. (2011) A multi-objective optimization framework for multicontaminant industrial water network design. Journal of Environmental Management, 92, 1802-1808. 

Jezowski, J. (2010) Review of water network design methods with literature annotations. Industrial and Engineering Chemistry Research, 49 (10), 44754 516. 

---