Fluidized Bed Combustion (FBC) Systems
- Due to the escalation in oil and gas prices continuously the world over, the power engineers were trying to develop new combustion systems with coal as fuel since it is available in abundance in India.
- In the earlier designs of furnaces using Pulverized coal were required to be operated upon in the temperature range of 1400-1700°C in order to get higher combustion efficiencies.
- But, at such high temperatures it forms slag on superheater tubes, it evaporates alkali metal in ash and its deposition on heat transfer surfaces causes fouling, corrosion and the reduced heat transfer rates.
- It forms pollutants NOX, in large amounts since the temperatures.
- maintained are considerably high. Sulphur content in the coal forms SO2, which in turn forms acids with moisture on condensation of steam.
- The capital cost for removal of SO2, from the gas is high.
- Another problem is that the furnaces designed for a particular type of coal cannot burn with every other type of coal with the same combustion efficiency and safety.
- The difficulties experienced by the engineers as enumerated above has led to the development of fluidized bed combustion (FBC) systems in which any type of coal could be burnt efficiently in the range of (800-1000)°C.
- Practically at these lower temperatures the production of pollutant like NOX, is lower since the fixation of atmospheric nitrogen is difficult to occur below the temperatures of 1100°C.
- Also, it reduces the problem of slag formation.