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Monday, 19 January 2015

Working of Fluidized Bed Boiler

Working of Fluidized Bed Boiler Points : Working of Fluidized Bed Boiler Fluidized bed combustion has given boiler and power plant machinist a greater flexibility in burning an extensive range of coal and further fuels. Every this with no compromise efficiency and by reduced contamination. Fluidized Bed at the bottom of boiler furnace present is a bed of motionless material. Bed is where coal or fuel spreads. Air provide is as of under bed at high pressure. This lifts bed material and coal particles and keeps it in suspension. Coal combustion takes place in this balanced condition. This is Fluidized bed. Particular design of air nozzles at bottom of the bed allows air flow with no clogging. Primary air fans give the preheated Fluidizing air. Secondary air fans give pre-heated combustion air. Nozzles in furnace walls at different levels distribute Combustion air in furnace. Circulation Excellent particles of partially burned coal, ash and bed material are passed along by the flue gases to upper areas of furnace and then into a cyclone. In the cyclone the heavier particle divide as of gas and falls to the hopper of cyclone. This proceeds to furnace for recirculation. The hot gases as of the cyclone pass to heat transfer surfaces and go out of boiler. To start by bed material is sand. A few portions are lost in ash during operation and this has to be invented. In coal fired boilers ash as of coal itself will be makeup material. When firing bio fuels by very low ash content sand will be the makeup bed material. For high Sulphur coals Limestone adding to bed material reduces SO2 emission. CFBC use compressed coal of 3 to 6 mm size. This requires just a crusher not a pulverizer. As of storage hoppers Conveyer and feeders transfer the coal to feed chutes in furnace. Start up is through oil burners in furnace. Ash spout in furnace remove ash as of the bottom of the furnace.

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