Smooth combustion of gaseous fuels in a novel configuration of fluidized bed

Abstract

A novel configuration has been developed and applied in burning gaseous fuels. It enables gaseous fuels to burn smoothly like a normal premixed flame avoiding acoustic effect acoustic effects and explosions due to volume combustion in bubble phase. A gaseous fuel partially premixed with air is fed through a jet pipe to be issued vertically upward in the upper part of the bed. The jet is able to establish a permanent fountain of particles in the freeboard. The remaining part of air is fed through the distributor to fluidize bed solids.Applying the proposed configuration confirms a rapid reliable method for initial heating of fluidized bed combustor. The experiments demonstrate that the bed temperature attains 800°C within about 10min. The normal acoustic effects and bubbles explosion due to volume combustion were not recognized.Temperature distribution has been measured in axial and radial directions. The obtained results indicate that applying the novel configuration dampens greatly the overheating in freeboard, in particular, at lower bed temperatures. The particles of created fountain absorb a great part of the heat released in freeboard and recover it back to the bed.Staged air combustion technique has been also applied using the novel configuration. Propane premixed with air is fed through the distribution while the remaining part of air is fed through the jet pipe to create a fountain. The obtained results demonstrate that the freeboard temperature rise is also greatly reduced.The power consumption in delivering gases to the combustor is found much lower when applying the proposed configuration rather than feeding all gases through the gas distributor. Moreover, bubble sizes reduce considerably in the main bed as only a part of gases passes through the main bed.