Combustion of pre-dried brown coal in a utility furnace using recycled flue gas

Abstract

This report describes a numerical study of pre-dried coal combustion in unit No. 3 furnace at TRUenergy’s Yallourn power plant. This utility unit is designed for raw brown coal without any pre-drying process. A validated computational fluid dynamics (CFD) model is used to investigate the combustion of the pre-dried coal with recycled flue gas that is added to the fuel gas. The temperature distributions, wall heat fluxes and heat supply to boiler for the recycled flue gas cases are similar to that of the raw coal combustion case under current operating conditions. Therefore, use of recirculated flue gas is proposed as the preferred option for future operation of the furnace with pre-dried coal. Nevertheless, further studies are essential to understand the technical and financial feasibility of using flue gas to maintain the fuel gas flow rate.