Optimization of cogeneration for power and desalination to satisfy the demand of water and power at high ambient temperatures

Abstract

This paper evaluates the technical and economic aspects of allocating a portion of desalinated water that is produced in Multi-Effect Distillation (MED) and Organic Rankine-Reverse Osmosis (ORC-RO) cycles to inlet air-cooling of a Gas Turbine (GT). Cogeneration of power and desalinated water ensures the feasibility of internal air-cooling in a site with high ambient temperature and lack of access to a high-quality water resource. So, a long-lasting supply of desalinated water leads to a reduction in the risk of the non-feasible proposed design. The Genetic Algorithm (GA) is used because of the complexities of the concept such as determination of the pinch and approach temperatures of the Heat Recovery Steam Generator (HRSG) and Waste Heat Recovery (WHR), determination of the organic fluid, maintaining the power production and desalinated water at a constant rate in different ambient temperatures, production of desalinated water in the RO system with minimum concentration, and finally, cost reduction of desalinated water production and cooling system consuming make-up water. The results demonstrate that using GA leads to an increase in the net desalinated water production by the rate of 14 m3/h and the net power of the GT by about 2.05 MW. Besides, adding inlet air cooling to the main cycle leads to an increase in water production from 393.75 m3/h to 400.0 m3/h in the MED section and from 92.1 m3/h to 100.37 m3/h in the RO section. Furthermore, the thermal efficiency of the GT improved from 35.5 % to 36.1 %.