Hi Derek,
We never conducted any studies on failure modes in my last place of work for the valves, we weren't in a good enough position but we did go off OEM and past experience, thinking what maintenance we had off the top of my head:
1. drive side checks - i.e. chain lubrication - just lubricate at intervals using interflon, gearbox oil replacement only - no condition checks as box was so small, gearbox temp using camera, inspection of sprockets and guard cover for signs of wear, inspection of chains for wear.
2. The actual valve itself we checked gland sealing by simply visual - no need to interfere if no dust was coming out - obviously tighten/replace etc as required
3. I don't remember any lubrication of the valve
4. in terms of valve wear etc we used inspection camera through the inspection port in hopper and admittedly there was very limited value in this.
5. We found a fault once as my younger hearing picked up a tiny squeaking on rotation - this was tough to diagnose but just as a FYI we did have a rotational scoring on the valve hence the squeak
6. On some valves we used to remove the whole rotating element as it was designed this way and others we left on bolts and span out - this was for a full inspection of blade to housing clearance and damage.
Think that's all we ever did and the faults we had. Technically I think most of those are condition based but not using technology.
Thinking quickly I would say the following would be good:
1. Yes do the drive checks
2. Camera was pretty useless
3. Swinging out was really intrusive - I wonder if ultrasound could be an avenue that could be used to detect a change in noise ?
4. Gland seal easy one
Our biggest issues was damp causing bridging and so valve was fine but product built up above so we installed airbrators near the valve to keep clear and then on a couple of real bad units we had vibrating hammer units which done the job - underlying cause was very aged assets and not sealed allowing moisture in to hoppers.
Not sure if that's answered you fully but that's my experience summed up.
For context - we had biomass, grain, soya and wheat dust and we used rotolok and rotoval valves.
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Keiron Arndell
Widnes
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Original Message:
Sent: 02-05-2021 10:11 AM
From: Derek Brown
Subject: Rotary AirLock Valves condition monitoring
Hi all,
Looking for some information from anyone who has experince of operating and maintaining Rotary AirLock Valves (RAL's) and if there is any recommended condition monitoring techniques they could recommend.
The RAL's on my plant are on hydrocarbon/polymers powder duty, failry large at 3.4te, 28" inlet/outlet, 19RPM, 800mm rotor diameter.
Thanks
Derek
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Derek Brown
Grangemouth
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