Balance Lauter Tun and grant

[gcbeer]

We are looking to improve the balance between our Lauter Tun and grant and not sure how to go about making adjustments (without trial and error). Anyone out there improved LT runoff times by making adjustments to the goose-neck dimensions? Is there a formula used during brewhouse design to optimize the balance between the LT and the grant?

[dick murton]

The trouble is that running off a lauter tun / mash tun is a balance between the time available, the extract required, the grind, i.e. how much husk / coarse / medium grits / flour there is, the bed depth, the amount of raking possible (if any). The traditional run off simply has a single, or sometimes a number of runoff control taps that have to be tweaked - nominally continuously, but in practice once a set of suitable settings has been determined - simply repeat with minor tweaks due to the inevitable variations.

Modern large lauter tuns work off differential pressures above and below the plates to achieve a flow rate which just avoids blinding the bed completely, which would then require a stop to runoff, deep bed rake and possible underlet to lift and help break up the bed. There are different ways of running small lauters, though the norm followed by the large suppliers is to keep the bed just flooded with a small layer of sparge water. Once the sparge flood is greater than a couple of inches it tends to lead to compaction of the bed at different points, and therefore uneven runoff and loss of extract.

If you had a modern large lauter from the likes of Huppman, Steinecker, Briggs and probably the small suppliers such as Nerb then based on their experience, they will get close to a decent runoff first time around, but will then spend a few days adjusting the grind and runoff to get to the target spec. For what it is worth, on a 7 day 3 shift operation with simple automation, it took me a couple of months to get something like a decent compromise runoff - you make an adjustment and have to let it run for a few brews to be able to judge consistency. So don't expect perfection in a couple of days.

Good luck

[gcbeer]

Height of Goose-neck

Hi Dick - thanks for the reply, that all sounds reasonable and it has taken some time to get it "tweeked" - and it sounds like we should keep going down that path until we get it really dialed in. We have 4 valves on the manifold coming out of the LT and adjusting those has made a difference, but I'm interested in the relationship between the goose-neck and the pressure above the v-screen.

In particular, is there an optimum height the goose-neck should be above the v-screen or does this dimension make no difference. The reason I ask is that the height of the goose-neck should create some back-pressure against the level above the screen but what should that be? Is there some way to determine this to get close and then make adjustments from there? The goose-neck height seems to make a difference in the flow rate just observing it with only water in the LT, but I don't know how important this is to the balance in actual practice with mash in the tun.
Cheers

[dick murton]

The only time I have run anything using this sort of control was an old mash tun with what was called a valentine. This had a variable height overflow, and we used to start off with it virtually the same height as the top of the mash, and then gradually lower it as the sparge progressed and the wort run off progressed and the wort became more diluted, until eventually it was the same level as the main mash tun floor, allowing the grain bed to dry out.

Effectively this is the same as having a flow control valve, or using your four valves as flow control valves, but as there is only one control, it is easier for a manual operation. (I would simply leave the four valves fully open and only use the goose neck as you call it) When I got to the brewery the operators had been using this method quite happily and getting good results, but when we had one of the MTs re-lined with stainless, I was able to reduce runoff times by two hours with virtually no loss of extract - so the brewery had been grossly underperforming for years.

I don't have a drawing of this setup, but have worked in micros since then with a single manual valve to control, and to be honest, would have found the variable height valentine / variable height flexi pipe system much easier to control runoff and prevent set beds etc. If you were to have a scale alongside, you could make this a really repeatable operation.

Don't know if this helps at all. I want to do a drawing for some training material I am slowly working through, so will try and get this done and post it soon.

Cheers

[gcbeer]

Balanced Flow

Just an update on this thread - using the idea of what Dick described as a valentine, I made a flexible tube to replace the gooseneck going from the manifold coming out of the LT to the grant starting at the original height above the grant. As the flow slowed down, because the level of the LT was dropping, I lowered the tube accordingly and the flow would pick back up to a normal run-off ( I originally thought this slowing of the run-off was the start of a stuck mash). I kept lowering the tube until it reached the lowest point it can go and adjusted the flow rate as I did this. I noted the best flow rate without reaching too great of a pressure differential between the LT and the grant. I modified the gooseneck to the desired height I reached during the testing. The LT and grant are balanced and my sprage times are very much improved.
Thanks for the input.

[dick murton]

Hey

Thanks for the feedback. It seems the old dwsign is still valid under at least some circumstances then. If I get to work in a small / micro again I might well have another go at implementing this control method myself.

Cheers