Induced Draft Fans And Their Applications
                     Induced Draft Fans And Their 
Applications
Neel Rao
Writes on Reitz India Centrifugal Fans & Reitz India 
Centrifugal blowers technologies.
What Are Induced Draft Fans?
Industrial induced draft fans are used mostly as a means to extract exhaust air from 
boilers. They usually focus on utilising differences in pressure and volume. In some 
cases, they are used together with forced draft fans, which helps to maintain a 
relatively low system air pressure steadily.
What Is An Induced Draft?
The difference between the pressure within the furnace or flue gas passage in a 
boiler system and the atmospheric pressure is commonly termed as a draft. 
Decreasing the system pressure below ambient pressure affects the flow of air and 
flue gas. This is known as an induced draft.
Induced draft fans are located between the chimney and the dust collector. It 
basically collects the hot flue gases and delivers them to the chimney. In large 
boilers, ID fans are also used to identify the combustion process being used.
ID fans regulate the air pressure within boilers and other systems and suck out 
discharged air through blowers. They also supply the boilers with the air necessary 
for the combustion process. This ensures the smooth running of the entire 
combustion process.
In steam power plants, ID fans and FD fans are used together to generate electricity 
through the combustion of fossil fuels. There these fans create a gradient of 
pressure known as draught. This gradient expels the burnt gasses out and sucks 
fresh air into the boiler. Several boiler accessories are located in between the 
chimney and the boiler. These help to make the power plant more efficient.
The ID fans are usually located at the base of chimneys. From there, they maintain 
low pressure in the boiler and the accessories. The low pressure helps to suck fresh 
air into the boiler and the accessories. They also drive burnt gases out of the 
chimney by maintaining high pressure.
Application Of ID Fans
Let us take a look at a brief overview of the applications of ID fans:
• They are large in size and exhaust primary as well as secondary air.
• They are used to expel gases into the atmosphere.
• To reduce the risk of explosion due to the pressurisation of the boiler, they create a 
balanced draft which helps to maintain negative pressure.
Basically, the job of an ID fan is to suck air through a system by creating negative 
pressure. Induced draft fans used in boilers must be capable of handling high 
particulate loadings and hot gases. The food processing industry witnesses 
considerable application of ID fans. There these fans help in cleaning the system of 
cooking odours. Other applications of these fans include ventilation and combustion 
processes.
In the industrial processes, ID fans get exposed to various harsh conditions. The air 
they process often include extremely hot gases, acidic streams of air, and other 
corrosive elements. While the ID fans are crucial to keep your system clean of these 
elements, they also pose a threat to the health of the fans.
Induced Draft Fans - Usage And Common Applications
The induced draft fans are used mostly in power plants, steel plants, cement plants, 
and the food processing industry. The most common applications are conveying raw 
materials and gasses. Almost any industrial process which involves the movement of 
air requires ID fans. These fans are used to handle a wide variety of materials in 
various industries and need to be manufactured accordingly. Evidently, induced draft 
fans are a key component in the respective industries.
About REITZINDIA
Reitz India has set a benchmark to deliver high quality fans for heavy duty industries 
which can work at precise operating conditions like high temperatures and pressures. 
Reitz offer idealistic Centrifugal Fan and Centrifugal blower design that can be used in 
all large scale process industries like cement, iron & steel, power plants, fertilizers/ 
chemicals and more.
Thank you for spending your precious time in reading this article!