A novel approach for optimal energy recovery using pressure retarded osmosis technology: Chemical exergy pinch analysis - Case study in a sugar mill plant

In the present study, pinch analysis is extended taking chemical exergy concept into account. The novel chemical exergy pinch analysis is proposed for sustainable power production by an economic application of pressure retarded osmosis membranes in chemical industries. Chemical exergy composite curves and chemical exergy cascade tables are developed as graphical and numerical tools, respectively. The tools are used to obtain maximum waste energy recovery by achieving various targets and determining the pinch point in a salinity gradient network. Thus, maximum energy recovery and minimum waste treatment are targeted, simultaneously. Moreover, a mathematical model follows the chemical exergy pinch analysis for an economic evaluation of pressure retarded osmosis-retrofitted industries under three probable scenarios. A sugar mill plant is simulated as the case study to validate the model-based analysis. The results showed that chemical exergy pinch analysis could efficiently provide the optimal pressure retarded osmosis -retrofitted industrial networks for decision-making. Having analysed the complex chemical exergy streams by chemical exergy pinch analysis, 11.30 MW net power is recovered with 0.038 $/kWh levelized cost of energy in the case study.