The current work presents numerical investigations of model burner in which a non-swirling air-assisted methanol spray is injected using a pressure-swirl atomiser. A stochastic breakup model is formulated in the context of Large Eddy Simulation (LES) and validated by detailed comparisons of the results with measurements. An excellent agreement is achieved for the non-reactive case in terms of the dispersion of the spray, the mean droplet distributions and the time-averaged spray velocities. The transported probability density function (pdf) equation/Eulerian stochastic field method are used to represent the interaction of turbulence and chemistry while the gas phase reaction of the methanol/air spray flame is described by a reduced reaction mechanism involving 18 chemical species and 84 elementary steps. The sub-grid scale (sgs) chemistry model in conjunction with the formulated breakup model are found to capture the influence of the flame on droplet dynamics together with the formation of a double reaction zone typically resulting from a polydisperse spray to a good accuracy.