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  • 1.  Slow rotating Machine

    Posted 12 days ago

    Hi everyone,

    I just wanted to get an advice what's the best solution to monitor very slow rotating machine or slewing ring on a Wastewater clarifier. The speed is 45 min per 1 revolution. Is it possible to apply vibration analysis (online) or is  there any other technique? 

    Looking forward to some help.

    Regards,



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    Romeo Jr Caseria
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  • 2.  RE: Slow rotating Machine

    Posted 11 days ago

    Brings back memories of some very slow slurry mixers I had responsibility for once and the vibration monitoring that worked very well was the old "earthquake" or mercury switch that tripped on vibration causing it to move position on its pivot point. We actually calibrated or verified operation by rapping the bearing housing with a hammer. Of course, following the PM's for greasing and inspecting the bearings prevented us from ever having a catastrophic failure. I guess, it you wanted to be high tech, you could permanently mount accelerometers on the bearing housing but probably not necessary. 



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    Victor E Rioli
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    Original Message


  • 3.  RE: Slow rotating Machine

    Posted 10 days ago

    Hello,

    if  speed is constant I assume that it works with a lot of equipment on the market. The problem is DC drives with a low speed that constantly changes speed of rotation , so there are no easy points.



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    Pantović Zoran
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    Original Message


  • 4.  RE: Slow rotating Machine

    Posted 11 days ago

    https://store.ncd.io/product/1-channel-industrial-iot-long-range-wireless-ultrasound-vibration-sensor/

    An Ultrasound sensor could be a good option

    Regards / Saludos



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    manuel ortiz
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    Original Message


  • 5.  RE: Slow rotating Machine

    Posted 10 days ago

    Use demodulated acceleration.  I have used this successfully down to 6rpm.  Also known as PeakVue, Spectral Spike Energy, Demodulation and many others.  The technique was pioneered by Diagnostic Instruments in Scotland which was later bought out by SKF.  Most analysers have this now but the trick is to use acceleration (not velocity) and make sure the Fmax is low enough to show the defect frequency. 

    One success was on a uranium grinder for BNFL.  The thing looked like a corn grinder and had a pintle bearing which supported the complete rotor.  One bearing had previously failed with fatigue cracking on the surface which contaminated the uranium that used in a fuel cell.  We took the reading on the other grinders and one of them showed 1X spikes (20rpm) in demodulated acceleration.  On stripping it down we saw the same surface cracking and that saved the customer a fortune.

    Good luck and let us know if you have issues

    Ron Frend



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    Ron Frend
    ron.frend@predicon.net
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    Original Message


  • 6.  RE: Slow rotating Machine

    Posted 10 days ago

    Hi Manuel,

    Looks like the sensor is the same as with our SDT Ultrasound Lube Checker. 



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    Romeo Jr Caseria
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    Original Message


  • 7.  RE: Slow rotating Machine

    Posted 10 days ago

    I think I would ask "what is the problem you're trying to solve" by looking for some kind of real time monitoring? Do you have existing planned maintenance shut downs where you can perform periodic condition monitoring by inspection instead that might meet the requirements of risk reduction?

    I have had some previous experience with ultrasound on slewing bearings for Azipods on ships - these move relatively slowly and not always in the same direction but still rotate relatively slowly.  Issues were still generally picked up by observation of an oil sheen if anything went wrong though.



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    Gareth Ward
    Chartered Engineer
    Enthusiast of all things Asset Management
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    Original Message


  • 8.  RE: Slow rotating Machine

    Posted 9 days ago
      |   view attached

    We have a failure some years back on one of these Reactors/Clarifiers. It was found out the slewing bearing/ring that drives the raker arm failed. Since then we've monitored this clarifier but only up to the drive motor and gearbox (planetary), the slewing ring is located underneath the platform and this drives the raker arm. Now we've heard some random knocking (not constant) sound. I suspect the sound is coming from the drive gears (worm) that drives the planetary gearbox. At this stage we looking at installing a real time monitoring but I'm not really convinced installing online VA might work due to the very slow RPM about 45 min/rev. Displacement probe or ultrasound might make sense. What do you think? 



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    Romeo Jr Caseria
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    Original Message


  • 9.  RE: Slow rotating Machine

    Posted 8 days ago

    Ultrasound technology would be a good fit. System that monitors 24/7 or is triggered to record 1 shaft revolution x times day. Here are a couple of solutions, the ultratrak can have output to PLC and record 24/7 and you do what you want with output, or use their DMS software as a spot check or use both

    https://www.uesystems.com/product/4cast/

    https://www.uesystems.com/product/ultratrak-850s-smart-analog-sensor/

    Dave



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    Dave Reynolds
    www.midlandsrc.com
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    Original Message


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