An industrial application of low-grade sensible waste heat driven seawater desalination: A case study

This paper reports on the application of low-grade sensible waste heat (liquid phase) driven multi-effect distillation (MED) technology to exploit waste heat sources that are generally abundant in the petrochemical industries especially, those located close to the Persian Gulfs coastline. For this purpose, a techno-economic feasibility study by considering local capital and operating costs for a selected petrochemical plant has been conducted. In this study, a sensible waste heat stream (practically at 80 degrees C in the liquid phase), which is actively cooled by the cooling process of the plant, is considered as the heat source for the proposed desalination process. This process can recover around 10% of the boiler-grade water demand (namely 644 m(3)/day out of 6000 m(3)/day) of the selected petrochemical plant. A detailed capital and operating costs and cash flow analysis are presented to show the economic viability of this kind of waste heat source for desalination purpose in petrochemical industries in Iran. Our study points to a net present value of 1.46 million USD with about 4.5 year payback period at a discount rate of 15%.