ENERGY-CONSUMPTION AND COSTS WITH A MULTISTAGE FLASHING (MSF) DESALTING SYSTEM

Energy consumption and costs are among the main parameters affecting t he choice of desalting systems and the final unit cost of the desalted water. In addition to the performance of the plant, the cost of the c onsumed energy depends on the quality of energy, i.e., either mechanic al or thermal and, if thermal, at what temperature. The cost also depe nds on the way this energy is applied (e.g., thermal energy can be dir ectly applied from a boiler or from cogeneration steam turbines or fro m heat recovery steam generators of gas turbines). The use of the conc ept of availability (exergy) to bring different kinds of energy to a c ommon basis of comparison is presented here. The way energy applied wa s considered in comparing the energy consumption of different desaltin g systems, namely, multistage flash (MSF), conventional multi-effect b oiling (MEB), thermovapor compression (TVC), mechanical vapor compress ion (MVC), and reverse osmosis (RO) desalting systems. A rational basi s for costing thermal and electrical energy was used to compare the en ergy costs of different types of desalting systems.