Residence Time Distributions in Confined Swirling Flames

Publisher Website
Google Scholar
Abstract
The objective of this work was two-fold: to determine the residence time distribution (RTD) in swirling pulverised coal flames and 10 develop a simple configuration of ideal chemical reactors, able to simulate the RTD. The work was performed using the solution of a mathematical model for a 2.2 MWth and a 12 MWth pulverised coal flame. Both flames are type II, resulting in high NOx emissions. From the mathematical solution the RTD was simulated by tracing a number of fluid particles or inert particles. The simulations showed that about 30% (dependent of the flame) of the fluid had a significantly lower residence time compared to the mean residence time. Based on RTD simulations and particle trajectories a simple configuration of ideal chemical reactors, able to simulate the main flow of the gas phase in the furnaces, was developed. The configuration consists of a plug flow reactor representing the jet centre, a well-stirred reactors representing the external recirculation zone, and a combination of well-stirred reactors representing the down stream region of the furnaces. The parameters in the ideal chemical reactor model were shown to berelated to distinct zones in the furnaces. Finally, the ideal chemical reactor model was verified against experimental RTD data of a 2.5 MWth confined swirling natural gas flame.