ID/FD Fans In Coal-Fired Power Plants

Coal-fired power plants have boiler systems where different types of industrial centrifugal fans are needed. While some of these fans supply adequate air to facilitate combustion in boilers, others remove the exhaust smoke or fumes from the chamber. This way, the air, and gases are circulated to ensure optimal heat transfer. The type of fans to be used depends on the size of the boiler in coal-fired power plants and the necessary airflow.

The commonly used draughts fans include induced and forced draft industrial process fans.

The article uses the words draught and draft as synonyms while describing the industrial process fans. In this article, we are going to discuss how these types of fans come in handy in coal-fired power plants.

What are induced and forced draught fans?
Before explaining what these two types of fans do, let’s understand why power plants need draught fans in the first place. In coal-fired thermal power plants, draught fans are responsible to maintain the flow of gases in the boiler. While forced draft fans help in circulating air around the boiler to facilitate better heat transfer and combustion, induced draft fans help in drawing the exhaust gases through the chimney. A calculated integration of both these fans in thermal power plants maintains the right pressure in the chamber for the combustion to take place.

Function of forced draught fans in thermal power plants
Forced draught fans are industrial centrifugal fans. Forced draught fans are responsible for supplying the necessary fuel to the combustion chamber. It pushes the air to the furnace. These fans are present at the boiler’s inlet and push fresh air at high pressure into the chamber. Here, it mixes with the fuel and generates the necessary pressure for the combustion to take place.

In thermal power plants using coal, forced draught fans are used as secondary fans. This regulates the combustion process and maximizes fuel efficiency. Both outlet and inlet dampers are necessary for an FD fan arrangement for controlling the air pressure inside the system. Forced draught fans are more efficient compared to induced draught fans. Besides, the operating conditions are cleaner and it is easy to maintain these fans.

Function of induced draught fans in thermal power plants
The key difference between induced and forced draught fans lies in the way they operate. While forced draught fans are responsible for pushing the air toward the combustion chamber, induced fans pull the exhaust gases from the combustion chamber to the chimney. Therefore, the toxic gases from the chamber get expelled into the environment with the help of induced fans. This explains why thermal power plants place these fans around the outlet, or between the chimney and the dust collector. Induced draught fans create a negative pressure or a suction force to expel the gases from the combustion chamber.

Why are both FD and ID fans needed in coal-fired power plants?
For the thermal power plant to operate, it’s imperative to maintain the right flow of air. An FD fan circulates air around the combustion chamber to ensure that the process takes place in the right way. On the other hand, induced fans draw the flue gases from the chamber and ensure a healthy operational environment. Power plants run by coal need both these types of draught fans to operate. It balances the air system present in the boiler, enhancing the efficiency of the combustion process.