Silo Auger Blues

Silo Auger Blues

Postby LeeMR on Wed Nov 04, 2009 10:29 pm

I'm about ready to cut up my low profile silo for scrap! That little round thing known as the auger, has been giving me "square balls" lately! I initially had some binding up problems, due to moisture getting in at the base of the auger, and hardening the cement. After disassembling the lower end of the auger, removing the solid concrete, then sealing the inspection door, we took care of that problem. Then it seized again, and it turns out that the lower shaft bearing failed. Great...so we fixed that, and figured we were done. It worked fine after.

Last Friday I got a load of cement. Well...let me back up. First thing in the morning, I loaded the truck before heading out for a job, and the auger worked fine. I came in later in the day, and my cement delivery showed up. While the cement was being loaded, under about 5-7 psi, I decided to top off my cement bin. I have done it before, loading my bin, while the silo was being loaded, and didn't have a problem. Well...this time, I started the auger, and after about 30 seconds, it stopped. I couldn't get it to turn. I thought that maybe a piece of hardened cement had been dislodged from the silo and bound up the auger, so again, I took off the inspection door at the bottom of the auger, cleaned it out, and there was nothing. Then I figured, well, maybe the top bearing went bad. I disassembled that, only to find that was not the issue. I still couldn't get the auger to move.

Finally, at my wits end, I drilled two 1" holes in the auger tube, at approx 1/3 intervals in the tube. I used my air compressor, and inserted the air line into each hole, forcing out the cement in the auger tube. SUCCESS!! The auger worked! Now, it appears to me that the cement in the tube was compacted, maybe due to the air pressure being used to fill the silo, while at the same time, I was loading my truck bin with the silo auger? I'm guessing that the additional pressure due to loading the silo, forced too much cement up the auger at once, and it bound the auger flighting.

Anyone else had experience with silo augers binding? I'm open for any suggestions.

Thanks,

Lee G.
Lee Gentile

MIX-RITE CONCRETE
http://www.mix-rite.com
888-MIX-RITE (649-7483)
228 Dedham Street
Norfolk, MA 02056
lee@mix-rite.com
LeeMR
 
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Location: 228 Dedham Street, Norfolk, MA 02056

Re: Silo Auger Blues

Postby Timberline on Wed Nov 04, 2009 10:50 pm

Lee,
We have had it happen a couple times, typically only when the silo is near empty and the new load of powder gets blown right into the auger. If there is still enough powder in the silo to keep the auger covered we never have issues. We just made a habit of always closing the lower "gate" when we are getting deliveries. We also asked our supplier to do the same if we were not around when he shows up. If we need to load during the delivery we close the gate halfway, production suffers but you can still get loaded and on the road. We are normally able to free up a stuck auger with a large pipe wrench on the shaft between the gear box and auger. We dont love our low pro silos and are exploring other options for the future.
Aron
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Re: Silo Auger Blues

Postby LeeMR on Thu Nov 05, 2009 10:18 pm

Hey Aron,

Thanks!!! I thought I was loosing my mind. At least it's not just me...lol. As I had noted, we drilled two 1" holes directly into the the auger tube, at about 1/3 intervals. We introduced compressed air, and freed the auger. I tried the pipe wrench, but to no avail. My auger hydraulic motor is attached directly inline to the auger shaft, with no reduction, so I don't think it produces much power to overcome a bound up auger.

Anyways, i went to reload today, and the auger was bound again! I again introduced air into the 1" hole I had drilled, and freed it up again. I got thinking about it, and wondered whether maybe my the filters in my bag house may be partially blocked, and thus caused excessive compaction of the cement as it was blown into the silo. I have to open the bag house, to see if that is the case. I'll keep you posted as to my findings. I agree though, I think my next silo will be an upright.

Lee
Lee Gentile

MIX-RITE CONCRETE
http://www.mix-rite.com
888-MIX-RITE (649-7483)
228 Dedham Street
Norfolk, MA 02056
lee@mix-rite.com
LeeMR
 
Posts: 52
Joined: Thu Dec 25, 2008 12:37 pm
Location: 228 Dedham Street, Norfolk, MA 02056

Re: Silo Auger Blues

Postby harberconcrete on Fri Nov 06, 2009 11:52 am

I Have run a the same low profile since 2000 and loaded my mixer while having material blown into silo with no problem, I am in CA and do not have much annual rain fall but the silos are water tight so rain should not be a problem unless they sit for an extended time unused. Do you have air pads/fluffers on your low pro?. The only problem that I have had is build up at the discharge tube at the top of the auger, make sure the opening has not been choked down. I would check this before opening the inspection plate. Good luck.
Brad Harber
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Re: Silo Auger Blues

Postby smnstn on Fri Nov 06, 2009 5:29 pm

These are all excellent suggestions. Being able to introduce air in the auger tube replicates an "air slide" which has always been a good way to keep powder fluidized. The physics of the lo-pro bulk bins leaves a bit to be desired as the shape is an upside-down pyramid. This means that the weight of the whole load resides on the small end of the bin. This shape is necessary for obvious reasons, but the flow of cement can be optimized by piston style vibrators and/or air diffusers located at key points (never right next to a support beam). Never operate the diffusers or vibrators continually while trying to bring cement down in the bin. Close your exit gate and "pulse" the devices for a few seconds with each pulse being a few seconds apart, just like the bin vibrators on your truck. When the cement breaks loose inside and falls down, if the auger intake is not protected, it will likely pack and stall the auger. Thus, if you have a way of loosening the cement in the auger, you'll have better luck freeing it up.

The size of the lo-pro bins is somewhat of a problem as well. If these are 200-barrel containers, that doesn't allow much room for the cement blown off the tanker to expand. One barrel (bbl) of cement is 4 cu ft, dry-rodded volume, or four 94 lb sacks. You can expect cement delivered by pneumatic fill to expand by at least 30%. So, if your bulk container is absolutely empty, it's 800 cu ft in capacity. Your delivered load will be about 575 cu ft. which is about 70% of your total volume. So, you can figure that if it "fluffs" by 30% while filling, you have to be dead empty to accept the entire tanker load without shutting down and allowing the cement storm in the lo-pro to subside. An additional complication is that you may indeed over-capacitate the filter bags. This will cause pressure to build inside the bin, instead of allowing it to escape. If there is a pop-off safety valve and it pops during filling, it's a sure sign the bags are plugged, or there wasn't room for a full load anyway. Most uprights are 250 bbl, or 1,000 cu ft these days to ensure being able to blow in a full load without having to run out of cement. About an hour after the tanker has left your yard is the time to shake the dickens out of the cloth filter bags with the manual shaker or attached vibrator.

Now comes the news I hate to bear. Most of these augers for loading cement are at the limit of feasibility for a straight auger. When the powder moving expert company WAM (no, not the Frisbee people) constructs an auger to move dry powdered material more than 15 feet, or so, they vary the flighting from half-pitch, to full pitch, to double-pitch. These things never jam; even when inadvertently packed tight with cement near the bottom. They also make a reverse pulse automatic self-cleaning baghouse that replaces the one with cloth bags. This thing has a stack of paper filters in it much like the old-style automotive air cleaner filters. The device cartridges should last at least one year, even in humid climates, and hooked to a source of clean, dry, compressed air, such as the supply on your truck, and activated when the bin is being filled. You shut it off and disconnect it when the bulk bin is full, and that's it. If it's mounted on top of the bin, trapped cement is returned into the bin. If it's down at frame level, you can manually transfer the trapped cement to your truck bin, or store it in a dry container for future use in patching masonry, etc. The WAM stuff is not cheap, but it sure eliminates a lot of problems. I'm also betting that all the bulk cement bin manufacturers know about it and will build it on to your equipment order for additional cost.

Simon Stanfield (smnstn)
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Re: Silo Auger Blues

Postby rono on Fri Nov 06, 2009 7:42 pm

hi lee,
dont kill the silo as yet let discuss her options give me a call 9545319830 or send me anemail....gordapeak@yahoo.com

thanks Ron
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