When a single centrifugal fan within the system cannot deliver sufficient airflow and pressure or if the fan is too large to install in the desired space, then multi-stage fan systems are used as an alternative for single fan system. Two or more separate centrifugal fans can be operated either in series or in parallel arrangements to serve specific requirements of industrial applications. When an increased volume or pressure becomes necessary for a process applications, multiple fans systems can be used either in series or parallel operation rather than simply replacing the original fan with larger capacity. Using centrifugal fans in multiple fan arrangements offer greater flexibility in unit sizing and also reduce the system noise.
Fan systems provide customized solutions in industrial applications for various purposes from cooling and exhausting heat to dust collection and material handling. The amount of air flow required, pressure and efficiency will decide which type of fan has to be used in the industrial process. Generally, in industries two primary types of fans are used - centrifugal fan and axial fan. These fans differ from each other in design, functionality and air flow direction.
Centrifugal fans are designed to serve specific requirements of industrial applications in which they are installed. The actual demand for pressure and the flow of air depends on the operational requirement and the designed capacity of the fan. Quite often, industrial applications require wide variety of operational conditions with a change in the airflow or fan speed. A typical centrifugal fan has the capability to increase the speed of air stream entering into the fan through an impeller, and accelerate it radially to the outlet changing its direction by 90°. Many fan systems need external mechanisms that can alter the designed fan capacity to achieve optimum efficiency and system performance. It can be either increase or decrease in the volume of airflow to make it appropriate for the specific operational needs. Industrial applications implement several methods to achieve this desired change in the airflow.
Centrifugal fan which is also called as squirrel cage fan because of its hamster wheel design is widely used to move air/gas continuously in industries and commercial applications. The speed of the air stream entering into the fan, is increased by the impeller thereby it gains kinetic energy and accelerates radially changing the direction by 90°. As these fans are capable of displacing constant volume of air/gas at increased speed, they are widely used in various process applications in industries such as in material handling, boiler applications, transporting gas or materials, ventilation and combustion, air circulation and in other HVAC systems.
The important reason for using accessories in centrifugal fans is to reduce the level of sound produced while working and protect the parts from weather if they are exposed outside. The main noise in the centrifugal fans is due to the vibrations caused in the equipment. Hence, there is a necessity to regulate these vibrations in order to reduce the sound level. For controlling vibrations in centrifugal fans, vibrator isolators are used. It is important to note that the accessories used in the industries must meet the safety of government norms.
Centrifugal fans, often called as blowers, are special type of industrial fans that are ideal for high pressure applications in several process industries and air pollution systems. Centrifugal fans increase the pressure of an incoming airstream by impellers, a series of blades mounted on a circular hub, which in turn accelerates air radially and alters the direction of the outward flowing air, usually by 90°. As centrifugal fans are constant volume devices that create steadier flow of air than axial fans, they are most widely used in various industrial processes such as in transporting air/gas and material handling.
Centrifugal fans and blowers have become a preferred choice for most of the industrial applications because of their relatively simpler design, durability and higher efficiency. Since a typical centrifugal fan has the capability to increase the speed of air stream coming through it, these fans are extensively used in industrial processes where large movement of air or gas is necessary. To get the desired high pressure and volume outputs, industries use different types of centrifugal fans with varied blade configurations in series and parallel arrangements. Yet, these fans may not achieve the desired airflow movement which is required for industrial process because of their reduced performance.
Routine maintenance and health check-up of the rotating equipment is essential for trouble free operation of the plant. This would also reduce the down time of the plant. It is recommended to refer the operation and maintenance manual of equipment manufacturer for any preventive measure. In case of any abnormal symptom monitored through sensors, should be attended immediately before the problem gets aggravated.
In many large scale industries centrifugal fans of high capacity provide optimal and cost effective solutions to deliver high pressures of airflow for various process applications. Generally, to get the desired high pressure and volume outputs, industries install two or more centrifugal fans in the series or parallel combinations. Sometimes, the option of multiple fans in the industries, may not be feasible due to limited availability of space in the working area. Hence to meet the demands of large scale applications in industries, a single heavy duty centrifugal fan can be used with high power rating. There are mainly two types of heavy duty fans that are widely used in industries, namely double inlet centrifugal fan and multistage centrifugal fan.
Cement industry is one of the major markets for industrial fans. Fans in cement industry are heavy duty and perform two basic functions i.e., supply of air or removal of exhaust gases and material handling. There are many process fans that find applications in cement industry such as raw mill fans, induced draft fans, cooling fans, raw mill exhaust fans, coal mill fans and cooler exhaust fans.