Fundamentals of retrofitting industrial fan and systemsJohn Terry, sales manager, Canada Blower | February 18, 2021
Industrial fans and exhausters are critical components in many industrial processes. Therefore, they are subject to the requirements associated with an increase in equipment life and a decrease in the total cost of maintenance.
It is often required that fans and exhausters operate at the limit of their technical capabilities. The higher the rotational speed of the fan blades, the higher the operating temperatures.
Fan modernization begins with an assessment procedure - a functional analysis of the equipment, an assessment of current faults. As a result, recommendations are issued on how the modernization should be carried out.
Fan manufacturers are ready to carry out all the necessary modernization procedures, from the assessment to the installation of new equipment, and is also responsible for the functionality of the equipment.
Blower Wheel is the most important component to regulate and control the air movement in the industries. Comparison of the characteristics of the original and modernized blower wheels showed that the modernized fan impeller provides an increase in air consumption by 24-30% at the same fan speed. The most dangerous from the point of view of the strength of the impeller are inertial loads from the rotation of the fan, which cause a concentration of stresses in the zones of the junction of the blades with the hub in the region of the leading and trailing edges.
Blower Wheels, as the most common device for moving gases in a space with a low compression ratio, are widely used in forced supply and exhaust and local ventilation systems for air volumes, in systems for blowing heating and cooling elements in heating and air conditioning devices, as well as blowing systems for radiators cooling various devices.
Blower Wheels are often elements of complex air systems that, due to physical features, have hydraulic losses, which reduces the efficiency of these systems. This condition always puts before the developers of fans the primary task of improving the technical and economic characteristics of these devices. The fan, as a device that creates a differential pressure for the movement of masses of air or gases in space, is a source of noise. Therefore, special attention should be paid to measures to improve the shape of fan impellers in order to meet environmental standards for noise levels.
Power transmission and components
Retrofitting of fans is the use of improved bearings and housings, lightweight pulleys in V-belt transmission, using tapered bushings and automatic lubrication systems.
The modern bearing’s housing design allows to apply an automatic lubrication system, which is a preliminary a flask filled with grease with an emptying mechanism (lubricator). It can work without the participation of mechanics for a specified period - from a month to a year.
Bearings are essential factors in extending fan life. The retrofit is being carried out to reduce operating temperatures and includes optimized bearings and housings as well as a new oil circulation system. Lower operating temperatures result in increased reliability, reduced maintenance costs and increased machine life.
Many fans are used to pump hot gases - with temperatures ranging from 212 ° F to 1112 ° F. Some of this heat is transferred to the bearings as a result of radiation heat transfer and thermal conduction of the fan shaft.
Operating at high temperatures can lead to bearing failure, which in turn causes unplanned shutdowns, downtime and production losses. High operating temperatures also have a negative effect on bearing lubrication as they shorten the life of the base oil. Deterioration in the lubricating performance of an oil means increased bearing friction, insufficient lubrication and possible bearing failure, which increases the risk of unplanned shutdown.
Retrofitting of industrial fans can be considered in changing the complete ventilation system in the building. Often, the owner of an old building does not want to make significant changes to the ventilation system, because this will supposedly greatly affect the building itself, especially if it is protected as a monument of antiquity. But often for reconstruction it is not required to cut walls, lay pipes, etc. As a rule, existing systems can be used. Otherwise, it will not be possible to achieve an optimal balance of costs and possible energy savings.
An updated ventilation system always requires a holistic approach and new calculations. Modern high-precision methods of calculation and modeling make it possible to optimally match the features of the building and the requirements for the ventilation system. And the improved models of electric motors and industrial fans take up much less space.
Based on current data, experts select the ideal components: electric motors, control devices and industrial fans of the latest generation. At the same time, there is no single ideal combination of components. The building owner will be provided with a comparative depreciation calculation showing several combinations of devices suitable for their energy saving program for instance.
Most of the time, most of the old system remains unchanged. Special attention is paid to electric motors, control devices and industrial fans, which always have to be replaced with new, more efficient equipment. Since the installation of heavy-duty industrial fans in old buildings often complicated, preference is given to more compact fans united in a single system. This provides an additional advantage as it allows to easily maintain or replace individual components during operation.
During the modernization of industrial fans, the noise level is also taken into account. Noise is harmful to health, and people are increasingly reacting to excessive noise. Before the refurbishment, the noise from the semiconductor manufacturer's ventilation system corresponded to the noise from a chainsaw at a distance of one meter, and after the refurbishment - the noise from a diesel engine at a distance of ten meters. As a sample an industrial fan shown right includes an acoustical blanket to reduce radiated noise.
Regardless of the positive economic aspects, the retrofitting of ventilation systems should also be considered from an environmental point of view. After all, energy reserves are limited, and they should be saved in the interests of future generations.
The listed solutions allow to optimize the process of modernization of industrial fans, increase reliability, safety and performance. This increases the total time of failure-free work, downtime is reduced, and maintenance and repair costs are reduced.
The main goal of implementing these technical solutions is to help improve the efficiency of production process and equipment return on investment.
About the company
Industrial fans and blowers produced by Canada Blower have been application engineered and designed to meet and exceed all the requirements of today’s air moving needs. We are experts in industrial process air and gas moving and heat transfer equipment.
If you can draw it, we can make it.