Heat Integration in Water Networks with Non-Isothermal mixing

The consumption of energy and water can be optimized through the synthesis of heat integrated water allocation networks (HIWANs). In HIWANs, water is conserved through re-use; while energy consumption is reduced through heat recovery. A combination of direct (non-isothermal mixing) and indirect (through heat exchangers) heat transfer is essential for maximum heat recovery. The incorporation of non-isothermal mixing required non-linear equations and/or integer variables to identify the nature (hot/cold) of heat exchanger streams. Using the concepts from Pinch Analysis, and an appropriate placement of the utility heat exchangers a novel linear programming model is proposed for HIWAN optimization. This allows the energy and water to be targeted quickly and efficiently. Additional water can be conserved through the synthesis of heat integrated water regeneration networks (HIWRNs) in which some amount of water is treated in regeneration units prior to re-use. Regeneration units, known as partitioning units, require the disposal of an impure stream as a part of the treatment process; while no waste needs to be disposed in single pass units. On contrary to the existing HIWRN synthesis techniques which use single pass units, this methodology is applicable to partitioning units as well. The methodology is demonstrated through an illustrative example.