What is induced draft and forced draft fan?

Induced draft implies an inlet fan placed on top of the cooling tower and the creation of low pressure. Forced draft means an exhaust fan placed at the base of the cooling tower which then causes overpressure. Both axial and centrifugal fans can be used.

What forced draft fans?

Fans that are used to pressurize a space or create mechanical air pressure in a system are referred to as forced draft fans. Forced draft is also used to identify the combustion process used in large boilers.

What is an induced fan?

An induced draught fan (ID fan) is provided to maintain a negative pressure in the furnace by sucking the products of combustion from it with a slight positive pressure at the discharge end vis-à-vis the bottom of the chimney/stack.

What is the purpose of a forced draft fan in a boiler?

Forced Draft Fans (FD) supply the air necessary for fuel combustion by pushing air through the combustion air supply system and into furnace. These fans are located at the inlet of boiler to push high pressure fresh air into combustion chamber, where it mixes with the fuel to produce positive pressure.

Why is induced Draught considered better than forced Draught?

The forced draught overcomes the resistance of the fuel bed there fore sufficient air is supplied to the fuel bed for proper and complete combustion. The induced draught fan removes the gases from the furnace maintaining the pressure in the furnace just below atmosphere.

Which tower is most efficient forced draft or induced draft Why?

Counterflow (induced draft) systems are considered the most efficient of the two. Crossflow (forced draft) towers distribute hot water perpendicularly to the air flow, while counterflow towers distribute hot water directly into the air flow.

What is a forced draft burner?

With this type of burner, all the combustion air is provided as primary air and they are commonly known as pre-mix burners. Air under pressure (about 70mbar) entrains low-pressure gas. With forced draught burners the fuel and air do not mix until they enter the burner head.

How does an induced draft fan work?

An induced-draft burner uses a blower to pull air into the burner, and through the combustion chamber and heat exchanger. The fan then pushes the flue gases out through the vent. This creates negative pressure in the furnace, and may create positive or negative pressure in the venting systems.

Where is the fan located on a forced draft burner?

Forced draft has the fan before the burner. An induced draft uses a blower fan to pull air into the burner through the combustion chamber and exchanger. The fan is located on the exhaust-side of the exchanger. It also blows the flue gases out through the vent connector pipe.

Which is most preferred type of Draught system?

Which is most preferred type of draught system? Explanation: A balanced draught system combines the features of forced draught and induced draught. In case of forced draught, when the furnace doors are opened high pressure air rushes outside and even blow out the fire entirely.

What is the difference between forced and natural Draught cooling towers?

Cooling water towers are described by the type and pattern of air flow. Natural draft towers rely on a “chimney effect” to obtain circulation of the air through the water. In forced-draft cooling towers, the air fan is located at the bottom of the tower.

What is the advantage of forced draft cooling tower?

Comparison Between Forced Draft And Induced Draft Cooling Tower

What is the working principle of induced draft fan?

Working Principle: Induced draft fan is also used to identify the combustion process used in large boilers. When mechanical ventilation is supplied to these boilers, the heat transfer rate increases. Induced draft fan or induced draft fans is always located between dust collector and chimney.

What is the function of forced draft fan?

Forced Draft Fans. The Forced Draft Fan (FD Fan) is a fundamental part of most boiler systems and is the element responsible for creating draft inside of the boiler. The FD Fan provides the pressure and flow required to push air, fuel, and the resulting flue gases created from combustion through the boiler, catalysts, economizer, FGR ductwork,…

What is induced draft fan?

Induced Draft Fan: Induced Draft Fan or ID fan is used to create a vacuum or negative pressure in a system like Steam boiler or Thermal Oil Heater. Working Principle: Induced draft Fan is also used to identify the combustion process used in large boilers.

How does a forced draft combustion fan work?

Forced Draft Fan supplies most of the Combustion air. This fan takes air from the atmosphere and blows it into the furnace through air ducts . The Air Heater heats the air before it enters the Furnace. Air Heater utilises the heat of the hot flue gases that leave the boiler to heat the combustion air. Hot air improves the efficiency of combustion.