Pulverised solid fuel is relatively easy to atomise on account of its small particle size (less than 90 micron), and hence burns cleanly and efficiently. However setting up a coal pulverising circuit is a very capital intensive affair. Adequate provisions are also required for inertisation in the entire coal grinding circuit, which makes the use of pulverised coal further capital intensive.
In order to avoid the capital expense of grinding solid fuels, Singhania System Technologist Pvt. Ltd. has developed a Fluidised Bed Combustion (FBC) based Hot Gas Generator for solid fuels. Unlike a pulverised coal HGG, FBC based HGGs are able to fire much larger particle size of coal/ solid fuels (less than 12mm).
The FBC combustor consists of a refractory lined furnace, ash settler, mixing zone for dilution air, Coal bunker with Screw feeder etc. The crushed coal along with an inert medium is fluidised on a bed of air and is combusted in refractory lined furnace to generate the required heat output and then mixed with Dilution air stream so as to give the required temperature and quantity of hot gases. The system is provided with combustion cum Fluidization air fan with necessary damper. A separate dilution air fan with damper is provided for the dilution of the Hot Gases produced through the fluidised bed combustion.