The size of the industrial fan is often overlooked when selecting a fan system for a new or replacement industrial application. Generally, industries use oversized fans to accommodate for uncertainties of future requirements. While some moderate oversizing is typically acceptable, choosing an excessively large equipment than the actual system requirement should be avoided. The size of the centrifugal fan should be optimal to the anticipated normal demand where it can operate at maximum efficiency for a given volume of air. Proper sizing of the fans involve determining all aspects of fan efficiency including airflow requirement and system effects at the fan inlet and discharge.
Excessive noise of a fan system can be a serious concern in industries. Higher noise levels caused by the fan systems can disrupt the productivity and cause nuisance to the working environment. The noise generated could be due to the turbulence effect at the fan blades or rotation of the fan shaft or motor. Typically, the noise produced by a centrifugal fan system is dependent on various factors including the fan size, airflow rate and pressure. Fan systems that work at optimum efficiency produce lower noise levels than the fans with inefficient operation. Using over sized fans for industrial applications or operating fans at higher speed produce vibrations, causing higher noise levels. The sources of noise in a centrifugal fan could be due to airborne or structure borne vibration levels. To identify where the issue is being produced and suggest solutions for specific noise issues, it is essential to understand the sources causing the problems.
Centrifugal fans perform the basic functionality of moving air from one place to another. There are several centrifugal fan types and sizes available each with certain application benefits. Since there is a great diversity in fan applications such as drying, cooling, conveying, aerating and ventilation etc the specifications needed for selecting the fan system also vary. A fan with right design and material, chosen by considering process requirement will enable good efficiency and reliability. Proper selection of the fan type is dependent on certain factors like fan type & size, airflow rate, static pressure, density of the air to be moved, system resistance, temperature range, space constraints, material to be handled, variations in operating conditions etc.
Centrifugal / Radial fans offer regulated high pressure airflow that is required for several industrial applications and air pollution systems. Centrifugal fans are constant volume devices and can operate under high sensitive conditions such as high or low temperatures, corrosive gases, acidic fumes etc. There are several ways how a centrifugal fan can be used as a process fan in industries, such as in transporting air/gas, drying, cooling, material handling, air re-circulation etc.
Blowers are used in industries when there is a requirement for larger volumes of air flow at higher pressures. A fan with higher pressure ratio (output pressure / input pressure) can be called as a blower provided it produces pressures as high as 1.20 kg/cm2. Like fan systems, blowers are widely used in industrial processes where a constant flow of air/gas is needed at higher pressures such as conveying material in dust collector systems, combustion air for burners, drying & cooling, general ventilation & circulation of air and so on. Blowers with higher efficiency are also used in industrial vacuum systems where suction or negative pressures are required.
The airflow requirement for an industrial process broadly depend on the operational conditions, material to be handled and system resistance. When airflow of a fan system is not adequate, typically industries seek alternatives such as increasing the fan speed or replacing it with a bigger capacity equipment.
To avoid facing issues associated with system airflow, industries have to ensure proper working of their centrifugal fan system. By employing certain maintenance procedures such as checking fan mechanical conditions and performingperiodicinspection of system components, the issues with system airflow can be rectified.
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: