Keywords: energy systems, exergy, steam power plants, second law, thermodynamics, exergoeconomic optimisation, steam turbines, fertilisers, thermoeconomic evaluation, aqua ammonia VAR, vapour absorption refrigeration
Exergoeconomic optimisation of steam power plant
The second law of thermodynamics combined with economics forms a powerful tool for systematic analysis and assessment of energy systems. This paper presents an exergoeconomic optimisation of 50 MW steam turbine power plant associated with a large fertiliser industrial unit through Thermoeconomic Evaluation and Optimisation (TEO) method, and identifies the losses in various components. As the industrial unit also operates aqua ammonia Vapour Absorption Refrigeration system (VAR) for its low temperature applications, the economy of the source of heat energy to VAR is also checked. For this, the cost of the part of bled steam at an appropriate tapping from the steam turbine originally meant for feed water heating proposed to be utilised as a heat source for VAR system is compared with the existing one. It is found that the use of heat source from bled steam is more economical than that generated in independent boiler or steam generated at HRSG of gas turbine power plant.