A pulverizer is a mechanical device for the grinding of many different types of materials. For example, they are used to pulverize coal for combustion in the steam-generating furnaces of fossil fuel power plants. Pulverised fuel firing is a solid fuel burning technique in which the fuel is pulverized before being ignited. It is the most common method of burning coal and oil shale for power generation. The basic idea of a firing system using pulverized fuel is to use the whole volume of the furnace for the combustion of solid fuels. Coal is ground to the size of a fine grain, mixed with air and burned in the flue gas flow. Biomass and other materials can also be added to the mixture. Coal contains mineral matter which is converted to ash during combustion. The ash is removed as bottom ash and fly ash. The bottom ash is removed at the furnace bottom There are two methods of ash removal at furnace bottom:
Dry bottom boiler
Wet bottom boiler, also called Slag tap
The fly ash is carried away with the flue gas and is separated in various hoppers in the path and finally in an ESP or a bag filter.