Araí Augusta Bernárdez Pécora

In Developping a Bench-Scale Circulating Fluidized Bed Combustor to Burn High Ash Brazilian Coal-Dolomites Mixtures

This work considers some of the questions in burning high ash Brazilian coal-dolomite mixtures in a bench-scale circulating fluidized bed combustor (CFBC). Experimental tests were performed with the CE4500 coal from Santa Catarina State, in southern Brazil, with a Sauter mean diameter d p =43 μm. The coal particles were mixed with dolomite particles of d p = 111 μm and this fuel mixture was fed into the circulating fluidized reactor, previously loaded with quartz sand particles of d p =353 μm. This inert material was previously heated by the combustion of liquefied petroleum gas up to the ignition temperature of the fuel mixture. The CFBC unit has a 100mm internal diameter riser, 4.0m high, as well as a 62.8mm internal diameter downcomer. The loop has a cyclone, a sampling valve to collect particles and a 62.8mm internal diameter L-valve to recirculate the particles in the loop. A screw feeder with a rotation control system was used to feed the fuel mixture to the reactor. The operational conditions were monitored by pressure taps and thermocouples installed along the loop. A data acquisition system showed the main operational conditions to control. Experimental tests performed put in evidence the problems found during bed operation, with special attention to the solids feed device, to the L-valve operation, to particle size, solids inventory, fluidized gas velocity, fuel mixture and recirculated solids feeding positions.

New particulate solids pneumatic feeding device with mass flowrate control

Abstract A new solids feed valve design was developed, based on the destruction of the repose cone resulting from the deposition of solid particles over a horizontal surface by fluidization of its base, followed by pneumatic transport of the fallen particles. Tests were carried out to determine the mass flowrate of solids of types A, B, C and D, according to Geldarts classification, as a function of the air flowrate.