Impact Of Design On Performance Of Industrial Centrifugal Process Fans

The industrial centrifugal fans are designed in a wide range of sizes for various applications. Designing a fan for a specific purpose is done by understanding the importance of the elements or factors that affect fan performance. A fan to suit specific requirements can be now be designed, due to the advances in turbine and jet propulsion technology.

Industrial process fans are used in the manufacturing industry for many applications. It may be truly said that no single type of fan is suitable for universal use in a manufacturing process plant. Although Industrial centrifugal process fans are available in many different designs, all centrifugal fans have the same working principle. The volume, velocity, and pressure of the air delivered at the fan outlet increase with an increase in the rotor speed of the fan. As air is expelled from the rotor, the housing collects the air and directs it out in a single stream.

Fans can be designed to meet nearly any requirement of pressure, velocity, and volume of air movement. Changing the speed of the wheel or adjusting the inlet or outlet will give the desired performance level. The need for adjustment in fans can differ for different fans, some need to be adjusted at their first use only, while others need to be adjusted at each use. Many times ordinary tools and common materials are adequate to design fans capable of delivering air at moderately high pressure and high volume.

The performance and efficiency of industrial centrifugal fans are also affected by the number of blades used in the impeller. Generally, increasing the number of blades in a fan will reduce slippage and thus increasing efficiency until the point is reached where reduced inlet area and losses due to friction will offset gains.

The number of blades in high-pressure radial vane is less while in high volume, low-pressure fans there are many blades. The number of blades that work well with different types of fans is as below:

• Commercially built radial vane fan: 5 to 12 blades• Backward inclined impeller: 10 to 20 blades• Curved vane squirrel cage fan: 30 to 60 or more blades• High-pressure fan: typically, 8 blades• High volume fan: typically, 16 blades

Many design considerations affect the performance of industrial centrifugal process fans, which are given below:

1. Impeller diameter and speed: With the increase in diameter of the impeller, the velocity of air also increases. If the impeller speed remains the same, the velocity of air is doubled by doubling the wheel speed.2. Air velocity: Static pressure resists the flow of moving air and reduces its dynamic pressure, this dynamic pressure which is remaining is called the velocity pressure. The velocity pressure delivers the moving air stream.3. Impeller width: Powerful, faster, and larger fans are needed in the pipe and complex duct systems where static pressure is high. The width of the impeller should be as high as possible when a high volume of air is the main consideration.4. Impeller-width-to-diameter-ratio: For some high-pressure wheels, the width might be as little as 5% of the diameter of the wheel. The impeller width will be much narrower with respect to its diameter and vanes will be deeper, when high pressure and velocity are required.

Along with this other design consideration that affect the performance of the industrial centrifugal fans are the nature of air, scroll housing development, general proportions of fans, and power required.

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