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Slow motion to make it more dramatic...
Number 4 mesh stainless screen over expanded steel framing. This is half a poly tank cut in half, with the screen subframe bolted into it. 4 mesh is like 1/8th open area between the wire. It's probably 98% open area.
Key to the process is to separate at or near boiling, and to balance the pump flow with the speed at which you are comfortable managing the squeegee - which is a critical piece of equipment. Without it, the screen will blind and the tank will fill with slurry, taking hours to drain.
The number 4 mesh will let small solids through, it's not perfect. Any tighter won't work well, as the screen will blind too quickly.
What size mesh are you using or is it wedge wire?
The grain pile at the bottom left of screen seems to still be quite moist. Do you leave it there to drain off the extra using gravity? Any squeezing or purther processing?
Number 4 screen mesh. I didn't buy it from here, but it's an accurate photo.
You can let it drain off if you want to take the time. The fact that it is coming off so hot allows it to dry a bit from the heat as well.
If I let it drain, it comes off relatively dry. If not, it's moist, but not wet. We pack into 20 gallon lock top drums for pick up, which are about as big as you can go if you are moving these by hand. In the drums it really doesn't matter if it's on the moist side.
We star san the drums before filling, and since the mash is boiled it's coming off relatively sterile. The grain holds pretty well in the lock-tops, even during the summer.
We've done many many tons this way.
About 1500 gallons on oak in the last few months.
Very cool. Did you try it running down an angled rack?
You might be able to up the flow and do away with the squidgy??
Will not work without the squeegee, the screen will blind. You need to physically remove the build-up of material from the screen for this to be effective. The skins from the corn as well as the small grains form a skin that completely occludes draining. This is not the same as lautering, as there is no longer any real grain solid structure, most of the remaining material is "mush", it does not form a self-filtering grain bed.
This is why most of the liquid/solid separation machines include physical wipers which rotate around the circumference of the drum to remove the blinding material.
If you allowed that entire area to fill, it would take about an hour and a half to drain, hot, and probably 3 hours to drain dry, cool.
Other issue is that you need a squeegee that allows you to replace the rubber wiper. The temp as well as the action really does a number on the rubber, we replace the rubber wiper about every two months.
An angled device might work slightly better, but I imagine you would still need to manually move material down the screen to the bottom to allow it to sit for a few minutes to finish draining off, and then scoop/shovel out. If you didn't I would imagine the screen would fully occlude and you would get a flow of liquid right down to the bottom - short circuiting the whole length.
This would not work if you hammer mill your grain, this requires some amount of solid and bulk to be effective. In most cases, the corn germ and all grain husks are still intact (I use medium crack corn and roller mill the small grain keeping husk intact).
A number 4 mesh is very wide, mush would go straight through.
I would imagine we are catching about 90-95% of the total solids volume.
A 530 gallon (2000 liter) mash with 1000 pounds of grain, we will fill 10 drums with probably 1000-1200 pounds of spent grain. The output bulk is roughly equivalent with the input bulk. Loss of starch being replaced with significantly more water weight. I've only weighed 2 or three drums, so this is a guess, but I think I'm close.
This is with the 4 mesh screen, which at initial glance will seem way too large of a gap to be effective. You would imagine you could probably drive a bus straight through 4 mesh.
But, I think this is the secret, any smaller and it would occlude incredibly quickly.
Just a quick note on how "wet" or "dry" this is. We have dumped all the drums in the back of a pickup truck, it's not so wet that liquid is draining out of the back of the truck when driving. If you grab a handful and squeeze it, you'll get liquid, but otherwise it appears relatively fluffy. I'll shoot another video of what the bulk solids look like in volume.
Scratch that, this is 6 mesh, not 4 mesh. This is still 1/8th opening (specifically 0.13"), I just got the mesh number conversion wrong.
I was wrong in what I posted above, it's 6, not 4.
Can a mod make the correction for me?
Various grain bills.
As low as 51% corn, and as high as 81% corn. Also grain bills with high glucanase grains like rye and wheat in excess of 30%.
No rice hulls used.
Grain bills that include whole oat with husks separate magnificently, the husk of roller milled oats blooms up like a flower.
Not 100% on topic but looking at the used grains, has anyone already looked into composting?
Found this on the internet and it looks like an aerated pile might yield compost soon. Looks relatively inexpensive and - given some outdoor space - could also yield a good revenue stream for the compost...
Spent grain is too hot (too much nitrogen). It would need to get cut with a significant amount of non-nitrogenous waste.
One of the local universities is working on a large scale composting program, I spent a little bit of time talking with them.
Initially, I was hoping they would take the spent grain, but legally they were not able to.
However, they told me that they need to cut their food waste with a significant amount of sawdust to have an effective composting system. They use huge rotating drums. They were interested in helping me setup a big drum system though, but I deferred. I don't need to be in the topsoil business too.
You would need to have a good source of additional material. Saw dust, shredded leaves, bark, chipped wood, etc.
This is the same problem as trying to compost grass clippings (including the stink).
Using Spent Brewery Grain in the Alaska Compost Pile (PDF)
Based on their read (O2), oxygen/air and temp control is the key for stink-less composting. I might give it a whirl next time with a budget an aquarium pump
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