How to protect the standby unit of the heating furnace flue extractor
Thread Content
Since the heating furnace cannot be shut down, a backup smoke extractor is required; it starts automatically when the main unit stops operating. Under normal operation, the backup fan does not need to be in use; it may not be employed at all throughout an entire production cycle. Since the flue gas contains corrosive substances such as sulfur, our fans get corroded after just a few months, and backup fans corrode even faster than those that are in use. As a result, they fail to serve their purpose as backups. Does anyone have experience with such backup fans, and what measures can be taken to keep them in good condition?
Although we don’t have such equipment, it’s clear that this is caused by low-temperature sulfur dew point corrosion. We recommend that, when the main unit is operating normally, you find a way to isolate the backup unit and connect a circulation line before the isolation point, so that the temperature in front of the isolation valve remains above the temperature at which dew point corrosion occurs – in other words, take measures to eliminate the conditions necessary for dew point corrosion to happen. This approach may be effective. In our installations, we generally use this method for areas prone to low-temperature sulfur dew point corrosion. The method mentioned by the person on the second floor, of switching between units periodically, can also be used.
Thank you both for your answers. It is indeed dew point corrosion. I don’t think switching the fans on and off regularly is a good idea, as the fans that are turned off will corrode quickly; it’s better to keep them running continuously. I still think it would be better to extend the continuous operating time of the fans and find ways to do without a backup unit; I’m not sure if this approach is the best one.