Simulation of Gas Turbine Combustion Chamber for CO₂ Emission Minimization

Abstract

In the present analysis combustion products of a 30 MW cogeneration cycle are studied on the basis of their concentration with change in cycle pressure ratio (CR). Mathematical modeling is done on the basis of exergy, energy and mass balance across the components. A computer program is made in EES (engineering equation solver) software and different parameters are studied for the analysis. For the present analysis air is considered to be a combination of N₂ (77.48%), O₂ (20.59%), CO₂ (.03%) and H₂O (1.9%). After combustion their concentration is changed. From the results it is observed that with change in cycle pressure ratio the concentration of N₂ and O₂ decreases and that of CO₂ and H₂O increases. Mass of CO₂ in combustion products is directly proportional to the mass of fuel injected in combustion chamber. With increase in cycle pressure ratio / compression ratio (CR) fuel consumption decreases upto a pressure ratio of 15 and after CR 15 it starts increasing again. As the fuel is the combination of the carbon and hydrogen, after burning with oxygen it generates heat energy, CO₂ and H₂O. Although upto a CR 15 mass of CO₂decreases in combustion products, but due to change in the concentration of other constituents, concentration of CO₂is increased. That is why concentration of H₂O and CO₂ in combustion product increases and that of oxygen decreases. From the results it is also concluded that increase in pressure ratio not only increases the efficiency of GT cycle but generates a concentration of N₂, O₂, CO₂ and H₂O in such a manner that specific heat (C_p) of combustion gas is increased.