Numerical Study of Gas Turbine Type Continuous Combustion Unit Burning LPG Mixture

Abstract

In the present work, burning of LPG mixture (50% each of propane C3H8 and butane C4H10) in a gas turbine type environment is simulated and validated against the benchmark continuous combustion unit (P. A. Hilton) experiment. Ansys Fluent® has been used to carry out the numerical study with major validation parameters limited to axial profiles of exhaust gas temperature and adiabatic flame temperature with equivalence ratio. It is observed that both exhaust gas and flame temperatures follow the theoretical trend of increasing with equivalence ratio, achieving their peak values at equivalence ratio near to unity and then subsequently decreasing. A pressure-based steady-state solver based on finite volume approach has been used to model the fluid flow with eddy dissipation limiters and realizable k-ɛ equations defining the combustion and turbulence phenomenon respectively. Axial profiles of important combustion parameters like temperature, pressure, and component mass fractions are obtained to draw out conclusions. The developed numerical methodology has been further extended to study the behavior of CNG in place of LPG and effect of air preheating on combustion. The study focuses on robustness of the solver and can be further expanded to include burning of liquid fuel sprays and their blends, variation of NOx, and study of flame characteristics in a continuous combustion-type environment.