Extension of targeting procedure for “Ultimate Flowrate Targeting with Regeneration Placement” by Ng et al., Chem. Eng. Res. Des., 85 (A9): 1253–1267

In our earlier work [Ng, D.K.S., Foo, D.C.Y., Tan, Y.L. and Tan, R.R., 2007, Ultimate flowrate targeting with regeneration placement. Trans IChemE, Part A, Chem Eng Res Des, 85 (A9): 1253–1267], a numerical technique was presented for determining the minimum fresh water and wastewater flowrates as well as the minimum regeneration flowrate in a water network with regeneration units of fixed outlet concentration model. The term ultimate targets were introduced to denote the minimum water flowrates. However, in some special cases, the proposed procedure does not lead to the correct ultimate water targets. In this work, the limitations of the procedure are first discussed, an extension is then proposed that arrives at the correct solution for more general cases.