Blowers are only designed to move air (gas), not solids. Overtime ingesting product can cause major damage to the blower.
This unit has ingested product for quite some time. Most likely failure to filter the inlet air caused contamination.
The product is now lodged inside of the impeller lobes and has abraded the tips and ends of both impellers. The wear of the impeller tips will reduce the efficiency of the blower. Where is the product going once it passes through the blower? Is the silencer starting to clog?
Impellers are worn from exposure to product (fly ash) in process. Caught early, most impellers are repairable by welding and machining. For a blower in vacuum service, contamination is a potential problem that might only be caught once you see the product exiting the discharge pipe!
For a pressure blower, contamination of the blower could be from running the blower backwards, or a failed/missing check valve. Introduction of material in the blower can also damage the blower by causing an inertia event:
- Spinning and then suddenly stopping
- Resting and then suddenly starting
- In both cases, energy can be directed in ways that are bad for the blower
An inertia event is usually when a blower is in operation and it comes to a sudden stop. The force of the sudden stop/slow-down is often very detrimental to the blower, i.e., bent and/or broken shafts, twisted drive shafts, cracked headplates and cylinders. Also, a blower can be spinning backwards from a faulty check valve and then be brought online, which applies enormous forces to the drive shaft as it has to overcome the inertia of the impeller spinning in the opposite direction.
The flyash has collected inside of the blower due to insufficient air filtration. The build-up on the back of the flange and at the headplate is common when material travels through a blower. The impellers will erode faster than the cylinder. Severe contamination of the blower can cause grooves at the cylinder headplate joints