Energy, Exergy, Exergoeconomic and Environmental (4E) Optimization of a Large Steam Power Plant: A Case Study

In the first part of the paper, the energy, exergy destruction and exergy loss of each component of a large power plant is estimated. The exergy destructions in the boiler and the turbine are about 86 and 8 % of the total exergy destruction of the power plant, respectively. In addition, the effect of excess air on exergy efficiency and CO2, CO, NOx emissions have been investigated. Finally, the optimization process is introduced by exergy efficiency, normalized CO2 emissions of the plant and three different cost functions consisting of the electricity costs, the costs of environmental effects and total plant costs. The results of the optimization by genetic algorithm have been compared, and the best objective function for the steam power plant has been detected. By choosing the optimum values of the operating conditions of the plant, the thermal efficiency and exergy efficiency increase by 9.7, 16.8 %, respectively. Moreover, the cost of electricity generation and cost of environmental effects reduce by 20.25, 49.6 %, respectively, at the optimum operating conditions.