Advanced Exergy Analysis of a Cogeneration Power Plant

Exergy-based evaluations done conventionally have some limitations. Traditional or conventional based exergy evaluation can point out the units or components with high exergy destructions and those with low exergy destructions. However, the system's components cannot be improved with this information alone. A component with highest amount of exergy destruction might not always be an ideal component for improvement. A component with relatively low amount of exergy destruction, however, might be improved. Conventional exergy analysis is unable to differentiate between the components with the highest and lowest potential for improvement. Because of this, advanced exergy analysis is very important for improving an energy conversion system. In this work, a cogeneration system made up of a steam power plant unit and a gas turbine unit is taken into consideration. To determine the enthalpy and entropy of water/steam, atmospheric mixture of air and mixture of combustion gases, an energy analysis of the entire plant is conducted. Methane gas is inoculated as fuel into the combustion chamber. Following the energy analysis, a conventional exergy analysis is conducted to determine how much exergy is being destroyed in both the system units and the individual components. Exergy efficiency, total exergy loss, product and fuel exergy, exergy loss ratio, and exergy destruction ratio are also determined. Exergy destruction occuring in the components is divided into various parts using advanced exergy analysis. The first law efficiency of the plant is found to be 36.45% when only the gas turbine power plant unit of the cogeneration system is taken into account. The plant's thermodynamic efficiency is 17.84% alone for the steam power plant. Now that the entire system is taken into account, the cogeneration system's first law efficiency is found to be 46.17%. It is obvious that the cogeneration system's first law efficiency has increased when it was compared to the individual units of the system. The second law efficiency and exergy destruction of the cogeneration system gas turbine power plant unit, when taken alone, are 36.45% and 32.89 MW, respectively. The unavoidable condition of advanced exergy analysis of the gas turbine power plant unit shows that the exergy efficiency has increased from 36.45 to 53.26% and that the overall exergy destruction has lowered from 32.89 to 19.22 MW when compared to the conventional exergy analysis. For the steam turbine power plant unit, it shows that the exergy efficiency has increased from 39.83 to 52.62% and that the overall exergy destruction has lowered from 9.48 to 6.72 MW when compared to the conventional exergy analysis. For the cogeneration system power plant unit, in comparison to the conventional exergy analysis, shows that the exergy efficiency has increased from 46.17 to 67.12% and that the total exergy destruction has lowered from 42.37 to 25.94 MW. The combustion chamber has the highest amount of unavoidable endogenous energy destruction takes place. The maximum internal irreversibility is therefore found in the combustion chamber. The HRSG in the steam turbine power plant experiences the most unavoidable endogenous energy destruction. The maximum internal irreversibility is occurring in HRSG. Also, the combustion chamber is the component where the majority of the endogenous exergy destruction takes place. The maximum internal irreversibility is therefore found in the combustion chamber. This is a result of the combustion chamber's extremely high temperature.