The quality and frequency of maintenance for fans and blowers are just as important as the quality of their design, manufacture, and installation. Just as we sometimes forget to maintain our own health and well-being due to our busy schedules, we tend to neglect the less obvious maintenance requirements of the fans on boilers. The fans are moving fast, doing their jobs; and, as with our own bodies, we might tend to fall back on the old, “If it ain’t broke, don’t fix it” adage. Unfortunately, there could be some “silent” killers working on your fan, robbing performance and moving the fan closer to an unplanned shutdown, which would kill the boiler(s) and the necessary flow of the hot water and/or steam.
The size and application range of boilers and their required fans vary widely. For simplicity, our focus will be on arrangement 3, 7, and 8 direct drive centrifugal fans on boilers up to 500,000 steam lb./hr. or approximately 150 MW as shown in Figure 1.