Lautering clarity

[Woolsocks]

I'm finally bugged enough about this to post and see if others have had this frustration:

I'm on a 15-bbl system, fairly new to it, and can't seem to maintain a clear runnings out of my mash/lauter tun. I get nice clear wort after a 20-30 min vorlauf, start lautering all is good. About 2/3 of the way through, little chunks of grain start showing up in my runnings. I can usually recirc to get rid of them, but why do they show up in the first place? I've played around with the mill gap, the runoff speed, the vorlauf speed, raking the top of the grain bed, etc. and nothing seems to change it. If it makes any difference to anyone, I seem to have high-gravity runnings for a while and then a major drop in the gravity of the runnings, rather than a steady decline. The clarity issue seems to coincide with the drop in gravity.

Tearing my hair out -- or would be if I had any. Hoping someone has some experience with this.

[Charles S.]

Same thing happens to me, but just on step mashes. Pullin hair as well. The problem is that I've done comparisons on flavor and the step mashes with the snow globe lauter finishes have a better malt character than the single infusion mash. I've messed with pH, grind, lauter plate leakage with no sucess. My strongest theory is that too much mixing in our mash tun, combined with a single roller mill, leads to beat up grain which loses integrity in the lauter. Been living with it for five years now.

[Todd]

Runawayrunoff

Gentlemen,

I can garantee your plates are bent inside your mash/lauter tun. Years ago I had the same problem at a small brewery (10bbl). The problem; Bent plates and Stokes law. Gravity will pull the particulate down once the viscosity of the wort falls. Your grain bed has a tendency to come apart when this happens. All of the gaps between your plates and your flanges will allow grain to come through. The answer; Put your drawoff up! In other words put in a stand-pipe!
I used a small piece of plastic tubing with the correct diameter to stick inside my drawoff port. I think it stood about 2-3 inches off the bottom. Yes, your efficienty will fall a little. I would rather have inefficiencies than poor wort quality. Try this out, let me know!!

I examined all things water related, pH related, grind related, mixing and stirring related and found this (STAND PIPE) to be the only solution.
I went back in the brewing records and looked at the last ten years of brewing. Our records indicated that we brewed a Barley Wine within the first year of purchasing the equipment, before this there was no indication of poor runoff. After brewing this we started to have problems. This was a Specific Mechanical System. I even contacted them several times. I also found out they had changed there engineering flaws and we had supports welded into our tun. This made things worse as it pulled the steel a bit making the gaps even wider.
In the end really inspect your plates. I never thought it could be the plates, but after carefull review it most certainly was!

-Todd

[Simha H]

Plates design.

I agree with Todd. The plates must be the source of all the problem. I have never worked at such low volumes but the principles of lauetering remain the same. You need to know the engineering of lauetering. The first bed formation with high gravity wort/mash slurry after rest forms a decent bed with pore size formed able to withstand the runoff pressure of wort friction. At this stage the chunks that you are talking about are not yet free enough But as the wort thins pore size increases and these chunks gain access to the plates. You will have to reduce the speed of lauetering and maybe form a entirely new bed with longer rest to tackle the problem. A reduction in lauetering speed will reduce your efficiency as well but will certainly give you a clearer wort.

[BMOOR]

third

I'll make it a third.
Also have Specific Mechanical.
Quite a bit of grain in grant, but wort is not cloudy.
My screens/plates definitely look 10 yrs old and I assumed that was the reason for grain entering the grant. Last brew we decided to put a mesh hop bag over the arm that outlets to kettle (post grant). Caught about 1/4 to 1/2 cup of grain particles. Is that a lot??? At least they didn't get in the kettle.

[scott isham]

I don't think it's the plates. The plates just act as a support for the grain bed, they aren't there to filter wort as some people seem to think. The matrix of the grain bed acts as the filter. Once the bed is set, there should be few if any chunks making it through. I find when this happened to me it came from running the vorluf to slow in the begining. I now open the vorluf pump wide open for about 5-10 seconds before slowing it down. That initial increase in pressure really brings alot of the fines through the pump instead of them settling under the screens to cloud up the runoff later.

Scott

[Michael Murphy]

could be caused by turbulent flow under the false bottom, you will always get something under the false bottom when you are mashing in, stirring will push smaller particles through. once the flow rate is changed, lower gravity can speed up and lift the particles which have settled on the bottom of the tank.

I agree that the best action would be to create a low stand pipe on your wort outlets. 1 cm is plenty.

merry christmas everyone!

[mr.jay]

I feel your pain, Woolsocks, I began a thread like this a few months ago. Go to page (2) of processes and techniques, and look for "odd sparging problem." You will find some good advice on there as well. I don't believe it's the false bottom plates either, only because it is not a problem I encounter every time. Based on the advice I was given, and the fact that I share some of the plumbing used in the kitchen. If they are running the dish machine when I am lautering, pressure drops, and I have to fool with the valves to maintain temp. (That's right folks! An hour and 20 minutes that could be better spent scaling hops, scrubbing, or doing other things is spent at the helm watching a temperature guage.). Anyhoo, because of the many variables in my situation, I haven't completely solved the problem. But it has improved, in that it doesn't happen when all of these variables are under control.
When all of the following happen correctly, I don't encounter particles in the sight glass during the lauter:

-I used to vorlauf rather fast, for 15 minutes. I've slowed it down (to match the speed that I lauter) and now re-circulation takes about 25-30 minutes.
-I open the valve ever so slowly to discharge the wort into the BK.
-I maintain consistancy in the speed at which I lauter. The way my system is set up, on a 7 Bbl batch, I need to begin pumping the mash at around 5.5 Bbls. Still, I don't speed things up.
-(this is the big one) I maintain a consistant temperature in the mash tun throughout the entire lauter.

[Simha H]

when the plates cause the problem

When the plates are over loaded above the given design specification or due to uneven bed formation may cause excess pressure to be exerted on certain plates. These are those plates over which the uneven bed has placed excess bed compared to others. This may cause the plates to bulge and cause space to develope between the two adjacent plates, enough for these flexible chunks to squeeze through.

[HWB]

Maybe it shouldn't be such a worry...

http://www.scientificsocieties.org/JIB/papers/2006/G-2006-1016-453.pdf

Cheers,
Tom

[Charles S.]

exactly...

[Moonlight]

Sounds like your bed is crushing and you are be getting a crack in your bed that is a shortcut for the sparge water, thus your quick drop in extract. I found a huge improvement in lautering by putting a flow meter on the sparge liquor. Eyeballing it always seemed plenty accurate and consistent enough untilafter dialing it in I found both significantly quicker and more efficient runoffs as well as less of my time tied up checking levels.
What you described happened from time to time to me when (especially due to a bit too much mixing) a fine layer of gummy proteins sealed off enough of the top of the bed so that the weight of the liquor on top compressed the bed. Next, as the liquor/wort wanted out the bottom and sucked down on the bed, cracks formed, either around the perimeter where they were less obvious, or somewhere in the middle. The sparge liquor rushed these crevases missing extract and carving out new riverbeds, eroding/carrying the malt particles in its path which gave more turbid wort. Cutting the bed with a paddle, (especially the top impervious gummy layer) helped immensely, yet mashing in wetter and adding the flow meter mostly prevented this from becoming a problem.

[Woolsocks]

I tried a stand pipe about 1cm and it didn't work. Then I tried it 2-3cm and it worked very well, with no reduction in efficiency. Or, the efficiency I lose with the pipe is the same as what I was losing by recircing again partway through. Wondering what the ideal height is for the pipe -- going to call Specific and ask.

[Woolsocks]

OK, just talked to specific. He says that there's likely a flaw in the plates where they don't quite sit flush with the frame beneath them, allowing grain to bypass them. The stand pipe solution, he says, is perfect. I shouldn't see any loss of efficiency or other problems. The only reason not to have one welded in is that it would complicate cleaning.