Examples of different types of fuels:-
1. Indian Coal : It contain 30 to 40 % ash but sulphur content is less than 1%.. 2. Imported coal: It contents low ash about 10% but sulphur content is more (1.2%). 3. Liquid fuels: Oil, diesel can be used to generate steam but it is not economical. 4. Gases fuel: Natural gas or manufactural gas can be used to generate steam. 5. Biomass fuel: Solid biomass fuel can be used to generate steam by burning directly in furnace. e.g. Agriculture waste, forestry waste, vegitable waste, commercial waste ,animal waste ,crops refuses, peel (cover) of fruits, domestic refuses etc. 6. Bagasse: -Waste of sugar cane. 7. Nuclear Fuel: Heat is produced by chain reaction of U 235 .
Advantages of liquid fuels over solid fuels:-
1. Less furnace volume required. 2. It requires low air pressure. 3. Firing of liquid fuel is easy. 4. No ash produces. 5. Time required for combustion reduces. 6. Liquid fuels can be transported easily through pipelines whereas solid fuels cannot be transports in this way. 7. Liquid fuels have higher calorific values than the solid fuels. 8. Due to liquid fuel amount fuel required to produce same amount of heat reduces. 9. It gives more heating surface area. 10. High temperature can be produce in furnace. 11. The requirement of air for complete combustion is reduced. 12. The firing can be controlled to match the load requirements. 13. Rapid and efficient starting of the boilers from cold.