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There are different types of fans that are used in industries, which increase the efficiency of many key processes. The most important of these fans are The ID (Induced Draft) fans, the FD (Forced Draft) fans, the PA (Primary Air) fans, and the SA (Secondary Air) fans. We shall now have a brief look at the various applications of these fans (also called as blowers) in the industries.
- The ID fans take in the flue gases having high levels of heat from furnaces and boilers. Then, they push them through a chimney into the outside atmosphere. As these fans remove the air that is present within the system, they generate negative pressure. The induced draft fans have a very long bearing life and this automatically lowers the maintenance cost.
- The way FD fans operate is different from the working of ID fans. The forced draft fans assist in generating positive pressure, as against the negative pressure seen in ID fans. The FD fans take in air that is present in the external atmosphere and direct it into the furnaces/boilers. This quickens the speed of the combustion process as well as increases its efficiency. Just like the ID varieties, the bearings of even the FD fans last long.
- Both the ID and FD fans come with a special feature- their power consumption is very low. Consequently, the manufacturer does not have to worry about a high electricity bill. The usage of these fans guarantees energy savings. Similarly, the two types of fans run with a very low level of sound and thus contribute their bit towards minimizing noise pollution.
- The induced draft fans regularly get exposed to hot gases. Therefore, they develop corrosion issues more frequently, when compared with the FD variants. And, the FD fans do not operate amidst harsh conditions and hence their efficiency level is high. The periodical maintenance of the forced draft fans is simpler, as well.
- The PA fans are extremely useful in plants where there are steam boilers with an outward furnace. As suggested by the name, the primary air fans generate the minimum level of air necessary for the completion of the combustion process. These fans ensure that the fuel particles get separated from each other. After that, the individual particles are enabled to directly get mixed with air and this enhances the efficiency of the combustion process.
- The SA fans are also pivotal elements of the plant. They are installed to supply more air to the system, in case there is some amount of primary air that has not been fully utilized. Many experts strongly voice the view that secondary air fans are not just optional. The presence of SA fans is mandatory if the process of combustion has to be properly completed.
- The primary air gets supplied from the lowermost area of the system, from where it gets transported using an airbox. On the other hand, the nozzles that are there over the furnace walls are the points from which the supply of secondary air takes place.
Making sure that the right volume of air is being supplied in all stages is very important. This is from the perspective of both bringing down the heat in combustion and facilitating the convective transfer of heat. The four kinds of fans mentioned above help realize this objective.