4E analysis of power and water cogeneration plant based on integrated MEDTVC and RO desalination units

Abstract

In this study, integration of RO desalination unit with power and water cogeneration plant located in Qeshm Island in Iran has been investigated. The desalination unit exists in this plant is MED-TVC type. In this regard, energy, exergy, exergoeconomic, and exergoenvironmental (4E) analyses have been performed by developing a computer code using Matlab. Validation of thermodynamic data has been performed through comparing the results of modeling by Matlab with the simulation done in Thermoflex software and the real data gathered from the Qeshm cogeneration plant. The results show the acceptable accuracy of thermodynamic modeling. The exergoenvironmental analysis has been conducted based on Life Cycle Assessment (LCA). In this regard, the weight function of TVC is proposed in this paper based on technical data in different nominal sizes in order to estimate the environmental impacts of this component. The cogeneration plant produces 25.7 MW power, consuming 6 kg/s steam can lead to production of 51.7 kg/s desalinated water. The gained output ratio (GOR) is about 8.7 for the MEDTVC unit. The performance ratio (PR) of RO desalination unit which is added to the downstream of MED-TVC has been calculated about 0.5. Integrating RO desalination unit with MED-TVC enhances the production of fresh water by 255.132 ton per hour. Exergetic efficiency, total cost rate of the system and total environmental impact rate of the system has been calculated 46.86 %, 64.01 $/min and 29.49 pts/min, respectively. Since the largest share of exergy destruction rate of the system belongs to the gas cycle and also Qeshm Island has a warm and muggy climate, adding a chiller type air cooling system to inlet of air compressor can decrease the power demand of air compressor and fuel consumption of combustion chamber which makes the system more efficient and reduce the cost and environmental impact rate of the system.