One of the significant risks to the performance and life-cycle of a fan system is vibration of the equipment. The vibration level of a centrifugal fan will determine its mechanical condition. If the vibration is too intense then it can become serious threat to fan operation causing forced shutdown. There could be many reasons for a centrifugal fan to have vibration issues, from a simple mechanical defect such as mass unbalance to more complex shaft misalignment, bearing failures or resonance problems. A fan system requires regular checking to determine the right acceptance limits of vibration. If the vibration is above acceptance level, then the fan system needs an analysis to look into the problem for rectification.
Retrofitting means upgrading the existing equipment to improve the efficiency and performance of the equipment. Retrofitting is usually performed in large scale industries such as cement industry, power plant industry where a complete new installation consumes huge amount of time and money. The basic need for retrofitting in industrial fans is to improve the performance of the existing fan.
Retrofitting is the process of upgrading an existing system by adding a new component or equipment. Centrifugal fans used in industrial plants are very large and they are retrofitted to improve the performance and efficiency. In centrifugal fans impeller is the most important component as it gives the necessary direction and pressure to the airflow. Hence, in case of centrifugal fans retrofitting of an impeller is important to regulate and control the air movement in the industries. When an impeller is changed it facilitates the change in other parts such as casing, inlet cones and shaft of impeller.
Centrifugal / Radial fans are machines whose primary function is to enable movement of large flow of gas or air for providing process relief in industrial units. These fans are specifically designed and built to operate at high or low temperatures, corrosive gases, acidic fumes etc., and are capable to handle different types of gases in any process plants. These fans find applications in several process plants as below:
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.