Blower are used for moving process gases with moderate pressure. It also increases the velocity of process gases. Blower or fan are uses for low pressure requirements whereas compressor are uses for high pressure requirements. When the resistance to flow is at the downstream of the machine, is known as fan or blower.
Whereas the resistance to flow is upstream of the machine, they are known as exhausters.
There many types of bearing uses in blower
Application of Fan or blowers
Fan are used for generally delivery pressure requirement is less than .5 psi but for blower delivery pressure requirement is .5 to 1.5 psi. The axial fan has higher capacity but lower discharge pressures as compare to centrifugal blower (fan).
The uses capacity is mentioned below.
- Circulating air in rooms or any other close confines area.
- For cooling and heating purposes
- Cooling motors, materials and products.
- For exhausting toxic, hazardous gases or exhausting dust
- For conveying very light materials
- Heat removal purposes by forced draft or by induced draft
Type of blower
Blower is also use for transfer gases or air like fans and compressor, but blower use for transfer non-pressurize air or gases.
Type of blower
- Centrifugal blower
- Positive displacement blower
- Helical screw blower
- High speed blower
|TYPE OF BLOWER|
Centrifugal blower uses for transfer constant volume of air or other gases, the operating speed of centrifugal blower is around 15000 RPM. Centrifugal type blower use in single or multistage impellers arrangement. The single stage centrifugal blower is uses for uniform airflow but whereas multi stage centrifugal blower uses for varying air flow at fixed volume required. In centrifugal blower uses high speed impeller to impact velocity to air or gases. In the impeller three types of blade are used like backward curved, forward curved and straight. Centrifugal blower is driven by an electrical motor, and that can be closed couple or coupled by a spacer and coupling to electrical motors. Affinity law (Fan) use for modification or any changes (speed, pressure, power) in centrifugal blower. Centrifugal blower are also use for transfer combustion air, for cooling or drying system. Sometime also use for fluid bed aerators with air conveyor system for dust control. In this type of blower air enter axially and exit radially. Relatively high efficiency almost 70 to 90 %. Forward curved blade impeller use for high volume and clean services. And efficiency range is almost 72 to 76%. Backward curved vane impeller has lowest efficiency and the range almost 77 to 91%. Radial vane impellers have efficiency almost 70% but it has stable operation.
Positive displacement blower
Positive displacement blower is uses for push the relatively constant volume of gases to outlet .it is uses for 30 to 65000 m3/h, and services like air, natural gases but it is oil free.
The axial flow blower is uses for transfer or move air or gases in parallel direction to shaft. Whereas centrifugal blower use for transfer air at 90 degree. As compare to centrifugal blower it has more capacity to transfer air. Based on the design axial fan are divided in three categories.
- Propeller fan the application are wall or ceiling mounted exhausts fan, cooling tower and air-cooled heat exchanger.
- Van axial fan- in this type of fan vans installed on the stator housing before or after the rote to direct and streamline the gaze for better fan action.
- Tube axial fans in this type of fan uses guide vane, but it is less efficient than other type of fans.
What are fan lows?
Fan laws the fan lows are basic proportional relationship between power, speed, diameter, and flow.
- The flow change in fan is directly proportional to speed.
Q2 / Q1 α N2 / N1
- The pressure change in fan is directly square proportional to speed.
H2 / H1 α (N2 / N1 )2
- The power change of fan is directly cube proportional to speed.
- P2 / P1 α (N2 / N1 )3