Combined gas turbine engine with water desalination system

The daily load schedule of a power plant is affected by the type of activities which may vary between day and night, as in industry, and from summer to winter, as for the air conditioning load in tropical regions. Hence, load management may play an important role in improving the load and capacity factors by increasing the average daily load and reducing the difference between the peaks and the valleys. This may lead to improvement in overall performance. This study is concerned with a power generation system in which steam and gas turbine power plants are interconnected. It is known that, at part load, gas turbine efficiency decreases sharply in comparison with the steam turbine, which remains nearly unaffected. Hence, if the spinning reserve and capability reserve are obtained from steam units, the gas turbine stays running at full load most of the time. The excess power could be used to run a vapour compression desalination system (VCS), and the exhaust energy could be utilized in a HRSG to produce distilled water from an MSF desalination plant. Performance analysis shows that this integrated system could save as much as 66% in fuel consumption and produce distilled water at about 4.75 million m3/yr. Thermoeconomic analysis shows that the additional investment could be paid back within 4.5 years.