Optimal design of cogeneration plants for seawater desalination

Multi-stage flash (MSF) and reverse osmosis (RO) are the most common techniques for seawater desalination. Asignificant difference between these methodologies consists of their different energy requirements, i.e., thermal energyfor MSF and mechanical energy for RO plants. The presence of both desalination systems (MSF and RO) appears tobe suitable for cogeneration plants. The reject heat from the power cycle can feed an MSF section, while some powerfeeds the RO section and the MSF auxiliary equipment; the rest is sold to the grid. A criterion for the optimal designof such tri-functional cogeneration plants is proposed, based on exergo-economics and on profit maximization. Inparticular, in this work the analytical model is presented by examining the required data, expressing the physical andcost balances and furnishing a comprehensive definition of the objective function. The proposed model is flexible andsuitable for comparative applications in all Mediterranean countries.