Hydrodynamic studies of CFBC boiler with three types of air distributor nozzles: experimental and CFD analysis

This paper presents the elaborated hydrodynamics studies of three types of air nozzles of CFBC boilers, types of air nozzles are bubble cap, arrow head and modified arrow head nozzles, and all these air nozzles are arranged in a 3 x 3 array and manufactured using FDM 3D print. The array of air nozzle is mounted onto the 200 x 200 x 2000-mm-transparent full-loop CFBC test rig. The different fluidization regimes for three types of air nozzles are studied. This research study is the sequel of the previous experiments where we had experimented different particle sizes, different bed heights and different velocities for a bubble cap nozzle, to avoid complication and number of experiments involving various velocities, bed heights, particle sizes and nozzles, and in this experiment we had kept bed height, particle size and velocity as fixed and nozzle geometry as variables. The bed height is kept as 200 mm from the distributor plate, particle size is taken as 200 mu m and velocity as 1 m/s. The parameters considered for this include the velocity, pressure drop and the regimes of fluidization. The hydrodynamic study is conducted both experimentally and computationally; the results are then compared to find out the most optimal design of nozzle among the three. Based on experimental and computation results, the modified arrow head nozzle is a good hydrodynamic stable air nozzle to be used in the CFBC boiler, though its pressure drop is more.