Coal Vac First Test...Not So Good

 
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CoalisCoolxWarm
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Post by CoalisCoolxWarm » Tue. Nov. 15, 2016 5:39 pm

davidmcbeth3 wrote:Larger piping needed?

I did it now......
Coal uses 8 inch pipe, right?

:P LOL.

I was thinking about that, too. The size of the coal vs the opening is....I'll go take a pic

 
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CoalisCoolxWarm
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Post by CoalisCoolxWarm » Tue. Nov. 15, 2016 5:54 pm

Here are some pics.
IMAG7333.jpg
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IMAG7331.jpg
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IMAG7330.jpg
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You can see how it doesn't slide down the hopper smoothly, either. Great coal, burns nicely. Just not much "flow" to it.

Think I should go to 2.5" or 3"? At 210 CFM, I have PLENTY of air. If not, I have a 220v dust collector nearby ;)

 
lzaharis
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Post by lzaharis » Tue. Nov. 15, 2016 6:23 pm

If that pea coal is not uniform in size your going to have to employ your dust collector.

The 3 inch piping will require quite a bit more amperage and pressure gradient to move
it. A dust deputy or a pair of dust deputies in front of your sawdust collector would certainly work well for you and not plug up the fabric as the fabric may be pierced by a sharp piece of fine coal or a nail-heaven for bid that of course.


 
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CoalisCoolxWarm
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Post by CoalisCoolxWarm » Tue. Nov. 15, 2016 6:34 pm

It seems that if the problem I am having now is due to the friction of the coal particles, I could go with a larger pipe to significantly reduce the effects:
PressureDrop_due to solids friction.PNG
.PNG | 66.9KB | PressureDrop_due to solids friction.PNG
Notice that pipe diameter (D) has a DOUBLE effect on reducing the friction. I believe I have plenty of air for the lift and transfer, and even for the Dense to Dilute phase acceleration losses as the air expands.

I'm fairly sure it's the friction at the opening area, mostly due to the size and shape of the coal- made worse as more weight is applied to the coal, forcing it to settle void into void and resisting any efforts to reorient individual pieces (as in moving to suck into the pickup tube)

What to do?

Obviously, vibration and other mechanical agitation can help. I know from personal experience that the right amount of agitation can set things in motion :P LOL.

What do you think about a larger opening of say 3" with about 8" of pipe, then reduce to 2" diameter?

The shift from Dense to Dilute phase should have enough length and space before the 2 inch section, which would then undergo its own Dense to Dilute phase transition, with the associated acceleration of the particles...which *should* spread out the coal pieces enough to accommodate the 3 in to 2 in change.

At least that's what I was thinking....Anyone try it? Results?

Dumb idea? Worst case would be a massive jam at the reducing point. But I think with the velocity and the fluid velocity over the coal to reduce the pressure, then the threshold to lift each piece might be enough delay to allow pieces to enter the stream in a "behaved" fashion?

If not, there's still a SHOVEL :shock: Haha !

BTW, here is a good document with the remainder of the equations, for those of you smart enough to digest and explain it to us all ;)

 
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CoalisCoolxWarm
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Post by CoalisCoolxWarm » Tue. Nov. 15, 2016 6:35 pm

lzaharis wrote:If that pea coal is not uniform in size your going to have to employ your dust collector.

The 3 inch piping will require quite a bit more amperage and pressure gradient to move
it. A dust deputy or a pair of dust deputies in front of your sawdust collector would certainly work well for you and not plug up the fabric as the fabric may be pierced by a sharp piece of fine coal or a nail-heaven for bid that of course.
Buckwheat sized. I think size is the issue. ;)

 
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Post by Dirty Steve » Wed. Nov. 16, 2016 9:00 am

For unoiled rice coal I run one 6.5hp and one 6.0hp shopvac each with dust deputy inline to the collection chamber above the boiler hopper. I use a smooth interior flexible 1.5 inch hose that reaches all of the floor of my bin. I suction from the top. It is still slow. 5 gallon pail in 48 seconds. I can suck in too much and plug the suction line. Is what it is- but I have not scooped or shoveled coal in a few years. 8-)


 
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CoalisCoolxWarm
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Post by CoalisCoolxWarm » Thu. Nov. 17, 2016 2:18 pm

Tiny bit better with the vertical 2" conduit.

We can move it around in the bin a little, like using the shopvac wand to pick up dirt, but that isn't the end goal ;(

It doesn't have any trouble at all moving it through the pipe once the coal piece is dislodged from its death grip in the bin ;)

LOTS of coal dust in the filter. Cleaned it out and noticed the improvement.

It is a vertical lift of about 5' (up to 6' eventually), then fairly level into the hopper.

I can reduce that initial straight lift a little if I cut another hole in the side of the bin. Maybe reuse the hole I made first...

Perhaps that is the direction I should go. Sloped to reduce the "entrance price" of the coal into the vacuum party, LOL.

 
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davidmcbeth3
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Post by davidmcbeth3 » Thu. Nov. 17, 2016 9:57 pm


 
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CoalisCoolxWarm
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Post by CoalisCoolxWarm » Fri. Nov. 24, 2017 2:56 pm

I'll be working on this again. This time I am planning on using larger piping and a Harbor Freight Dust Collector.

What is the max angle for an auger in a pipe?

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