The present work deals with a theoretical study on the performance of a combined power and desalination plant. The power is a simple gas turbine unit (GT) while the desalination is composed of thermal and membrane systems. The thermal desalination consists of a multiple effect distillation (MED) with thermal vapor compression (TVC), and the membrane plant is a reverse osmosis (RO) with an energy recovery device (pressure exchanger system). The modeling is based on appropriate evaluation of the sea water properties including that of flow exergy and the solution of mass, energy, and exergy balances for the main components of the power and desalination plant. The simulations include typical data on actual GT units. The effect of the main controlling parameters of the GT plant mainly the pressure ratio and the turbine inlet temperature on the total production rates of fresh water is presented and discussed. An exergy analysis showing the destruction rates of the overall system as well as its main comp...

Performance analysis of a gas turbine unit combined with MED-TVC and RO desalination systems

This study focuses on an individualised exergy analysis approach for optimising the exergy efficiencies of the high irreversible components for a new discharge thermal energy combined desalination (DTECD) system. DTECD is a newly introduced energy recovery system to use the latent heat of waste steam. It is a combination of closed and open thermodynamic cycles, which cogenerates power and pure water. Based on the extra steam in an ammonia plant, two scenarios were modelled with respect to the exergy performance, which were individualised to find the irreversibility of each component. The results showed that exergy efficiency of the entire system is about 50%. Also, it was found that the working fluid evaporator and vacuum flash desalinator were the most exergy destructive equipment in the closed power cycle and open water cycle, respectively. The performance of the DTECD system utilising a vacuum single-stage spray flash evaporator is compared with similar technologies. Finally, recommendations ar...

Optimised exergy efficiency of a combined flash spray desalinator recovering discharge thermal energy

Technoeconomic assessment of a concentrated solar tower-gas turbine co-generation system

Population of the world is increasing and so the demand of energy for domestic and industrial use. Worldwide efforts are being meet to produce energy from renewable resources but it is impossible to replace the fossil fuel resource of energy. Gas turbine remains the main energy converter of fossil fuel both for its liquid and gaseous states. This paper analyzes the performance of a unit of an actual power plant situated at Riyadh, Saudi Arabia. The power plant has G.E. gas turbine units which operate as simple gas turbine units at peak demand periods and as a part of combined power plant unit at other periods of operation. The performance of the unit has been evaluated from the actual data from the unit obtained around the year. The study reveals that for gas turbine cycle an increase in compressor inlet temperature increases efficiency of compressor whereas turbine efficiency decreases. Exit temperature of the unit increases with the increase in inlet temperature of compressor that results in enhanced pollution. The exergy and energy efficiencies of the whole unit show dependence on compressor inlet temperature. Plant efficiency and mass of steam produced increase with the increase in the turbine inlet temperature.

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Performance of a Gas Turbine Power Plant

This work deals with a thermodynamic analysis of the performance of a cogeneration gas turbine and thermal desalination plant. A heat recovery steam generator links the two units together. The analysis is based on the application of mass, energy and exergy balances on the whole cogeneration plant as well as on each of its components. The analysis is also based on an accurate evaluation of the seawater properties, which leads to correct calculations of the flow exergy and exergy efficiency of any component of the desalination plant. The main results of the study concern the influence of the pressure ratio of the compressor and the turbine inlet temperature on the exergy efficiency of the gas turbine and the whole combined system. It was found in particular that as the performance ratio of the desalination plant increases the specific exergy destruction rate decreases.

A. Al Zahrani

Papers

Thermodynamic analysis of a cogeneration gas turbine and desalination plant.