Coal Vac First Test...Not So Good

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CoalisCoolxWarm
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Location: Western PA

Post By: CoalisCoolxWarm » Sun. Nov. 13, 2016 5:36 pm

So connected my coal vac prototype from last year out through the basement wall and into the coal bin to magically transport buckwheat coal into my boiler hopper.

3-2-1...FIRE! Coal is heard scraping through the pipe and slapping into the bucket above the coal hopper. Awesome.

...for about 5 seconds :(

Out to the bin to see what is happening. Shake the pipe, return to glorious coal-ruckus.

...for another 30 secs or so :(

I have the end of the pipe straight cut with a little snorkel. If I shake the pipe it grabs the coal and it flies through the system into the bucket. If not, it seems to pack together and not go into the pipe.

There isn't much coal on the pipe, we dug a hole for the pipe, inserted the pickup end of the pipe, and covered it with about 2 inches of coal.

I see some of you guys are cutting the end at an upside down 45 degrees. Think that will help?

I'm using a 6.5hp vacuum with about 210cfm. Should well exceed the necessary suction.

Coal is last season's, so plenty dry ;)

Thoughts and ideas?

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lzaharis
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Post By: lzaharis » Sun. Nov. 13, 2016 6:03 pm

NO snorkel!! It reduces the available pressure gradient generated by the shop vac to pull the coal through the piping to the tank above the hopper. the snorkel also affect the ability of the hoppers closure to seal tightly.

With the sloped inlet cut into the pipe in the bin it lets the pressure gradient created by the shop vac work more efficiently and pull the full volume of air through the pipe with the coal in a diluted volume that travels through the piping to your tank.

What you and everyone else with the coal vac systems is looking for is what is referred to as the "Dilute phase transfer of solid particles".

Wherein the stream of particles pea and rice coal is carried by the air stream created by the Vacuum (pressure gradient in HG inches of water column) used to pull the solids from point A-the bin to point B the tank above the hopper of the stoker.

The same principle is used to monitor your stoker with the the Dwyer Mark II Manomometer

The "Dense Phase Transfer Of Material" is what is used for honey wagons and sewer and storm water catch basin cleaners that creates a huge pressure gradient measured in Vacuum "HG inches of water column" to pull the material through the hoses into the tanks.

I hope I did not put anyone to sleep. :cry:
Last edited by lzaharis on Sun. Nov. 13, 2016 11:10 pm, edited 2 times in total.

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davidmcbeth3
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Post By: davidmcbeth3 » Sun. Nov. 13, 2016 6:06 pm

Sounds like the coal is damming up (ie either coal size to large for pipe or pipe is to small for coal .. what size piping being used?

I have my (not yet completed due to vacuum needing work with the filter) in my ash-sucker (clinker about the same as coal in not larger) prototype and made a "large clinker catcher" because some large clinkers were clogging up the line.

Simple enough to build...sealed bucket with pipe that has a hole to allow the large pcs to drop while still sucking through the smaller ones. It solved my large-clinker-clogging issue.

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McGiever
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Post By: McGiever » Sun. Nov. 13, 2016 6:07 pm

That is called "bridging", where coal supports it self around a pocket absent of coal.

Bigger hole (45* cut) maybe or some method of agitation to upset the bridging.

BTW: Wet coal is slipperier than bone dry coal. ;)

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CoalisCoolxWarm
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Post By: CoalisCoolxWarm » Sun. Nov. 13, 2016 6:45 pm

"Dense Phase Transfer Of Material"? Cool, I'm doing something all "physics" and stuff :P :D

I'm using 2 inch electrical conduits with sweep elbows.

Here's my earlier post, showing the prototype in the basement a few months ago.

CoalisCoolxWarm @ Coal Vac- How to Lay Pipe in the Bin?

No snorkel? I thought that was supposed to reduce jamming? We did get better suction when my daughter help her hand over the snorkel, but it didn't seem to help the pickup end "bridging"

I added a vibrating part last year and got a little better results.

As-is, fairly certain it would be jammed up if I filled the hopper with coal. Trying to work out the design and mods needed to be solid and reliable before we run out of coal. Pretty low at the moment, using about a hopper a week (275lbs hopper)

I'll be changing out the bucket for something a bit larger and sloped once the pickup is fixed.

Thanks! :cheers:

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swyman
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Post By: swyman » Mon. Nov. 14, 2016 1:50 am

I ran into this years ago when I had my corn setup. I think you need to add a bleeder valve (if that's the right term). I added a ball valve on the handle of the wand that I could open to limit the suction of material. At full suction the pipe would fill up and material would be to heavy in the pipe to move. By adding a bleeder valve you can open to suck outside air limiting how much material flows through the system. I really worked great! I was pulling the material 12' vertically to the storage bin with a single 6.5hp craftsman shop vac.

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CoalisCoolxWarm
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Post By: CoalisCoolxWarm » Mon. Nov. 14, 2016 12:22 pm

Vertical pickup tube? I see that advice in last year's thread. My memory isn't what it used to be :oops:

Fortunately, we've only friction fit the pieces, even though we did cut some to size. Shouldn't be too hard to rework.

Probably Thursday we'll have used enough coal that we can try again ;)

Corn, eh? Cool.

Thanks, guys!

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Post By: swyman » Mon. Nov. 14, 2016 1:55 pm

CoalisCoolxWarm wrote:
Corn, eh? Cool.!
It was when the price was $1.50/bushel when I started, 2 years later it went to $4.50! That's what got me into this alternative fuel mess, now I'm addicted!

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CoalisCoolxWarm
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Stoker Coal Boiler: Keystoker KA-6
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Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler
Location: Western PA

Post By: CoalisCoolxWarm » Mon. Nov. 14, 2016 3:42 pm

swyman wrote:
CoalisCoolxWarm wrote:
Corn, eh? Cool.!
It was when the price was $1.50/bushel when I started, 2 years later it went to $4.50! That's what got me into this alternative fuel mess, now I'm addicted!
We need Food and Fuel in sufficient and affordable quantities. When one cannibalizes the other... :(

lzaharis
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Post By: lzaharis » Mon. Nov. 14, 2016 5:12 pm

If you have a bin already set up:

Building a coal dog house for the end of the suction tube would
help you a lot by keeping just the open end of the vacuum in the bin.

The pipe would not be blocked or have the coal bridge over/rat hole
and create a void as the coal will simply drop and not compact creating
bridging/rat holing in the bin.

The ideal bin set up is having a sloped bin wall feeding the dog house
opening.

There is information here on the forum and EFM has a nice section on
a dog house in a coal bin to feed coal to an EFM auger fed stoker.

You would have to move coal over to the suction pipe by hand eventually but
the coal dog house would let you manage it from one position, WOOOF!!!!!!!!!!

The thing about corn is the corn kernal is larger in total size and volume and essentially lighter and easier to move with a system creating a negative pressure gradient to move granular material using The Dilute Phase transfer of material.

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CoalisCoolxWarm
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Stoker Coal Boiler: Keystoker KA-6
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Coal Size/Type: Anthracite Buckwheat
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Location: Western PA

Post By: CoalisCoolxWarm » Mon. Nov. 14, 2016 6:50 pm

It's not a big deal to change the location of the pipe. We ran it through the old coal bin door, so there's quite a bit of adjustment available until we build a new enclosure there.

Stuffed the opening with cardboard and insulation until this gets worked out in the next week or so. Real high tech, you know ;)

The vertical pipe makes a lot of sense to me. The coal under the pipe couldn't really get compacted because of the pipe being above it. I wonder it it would be better to have a larger pipe over top of the suction pipe, to widen the footprint of the area above the pickup foot that wouldn't have direct weight over it?

I searched for "dog house" but this was the only thing I found:
Did you know that searching this board with quotes around a phrase still splits the search into just individual words? Phtt...

lzaharis
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Post By: lzaharis » Mon. Nov. 14, 2016 7:47 pm

That is the side view of a dog house for a coal auger
the sloped front allows the coal to fall by gravity to
the opening where the auger is just past the sloped
portion of the bin or in your case the pipe with the
slice cut out of it to have sloped entrance.

As the coal drops around the pipe as its working it
creates the channel needed to allow the coal to be
transferred through the pipe to the tank.

It can be modified slightly to increase the amount of bin covering
the pipe or the pipe can be repositioned to have just the cut end
exposed past the roof of the dog house.

NOW please understand this:

Every vertical foot of travel and every elbow in your system
makes your system work harder than it has too as an elbow
adds 50 feet of resistance to the system if my memory is right.

I do not want to bore you to a snore with the details I just want
to help you with your system.

The fewer bends(mild slope), the larger the horizontal run and distance in one lift the
less energy required and the less coal dust that will build up in
the elbows which is an effect called "siltation" in a pipe.

The other option is of course is the conga line of shop vacs and
a dust deputy to create more of a pressure gradient to move the
material.

If you could rent a plastic conduit heater to shape the sweeps
to less of an angle that will help you a lot in reducing the internal
friction the pressure gradient has to work against to move your
coal.

Or just heat the pipe to install it making a gradual slope to the tank
if you have room.

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CoalisCoolxWarm
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Stoker Coal Boiler: Keystoker KA-6
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Coal Size/Type: Anthracite Buckwheat
Other Heating: Oil Boiler
Location: Western PA

Post By: CoalisCoolxWarm » Mon. Nov. 14, 2016 8:48 pm

I do understand and appreciate your efforts to help us implement a reliable and effective system ;)

Right now I have a couple of elbows to make things connect. At the end I intend to shorten and increase the efficiency of all the runs.

Above all, I do NOT want to be out there digging in the coal bin in the winter to unclog my pipe :shock:

Whatever I have to do, let's get it worked out now ;)

Thanks! :cheers:

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davidmcbeth3
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Post By: davidmcbeth3 » Tue. Nov. 15, 2016 2:29 pm

Larger piping needed?

I did it now......

lzaharis
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Post By: lzaharis » Tue. Nov. 15, 2016 2:40 pm

Nope, we just need a coal dog house in his bin and a conduit heater
to bend his pipe. Adding windshield washer fluid to a coal pile will make
it flow better as it will break up the ice and melt it if he has any ice in the
coal and then just let it evaporate away.

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