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-   -   Automation - Stirring Grains in the MLT (http://www.homebrewtalk.com/f13/automation-stirring-grains-mlt-35667/)

nabs478 08-06-2007 04:52 AM

Automation - Stirring Grains in the MLT
 
Howdy boys and girls,

I am scaling up my operation and looking into automation. I've got some good idea from this forum and from the Australian equivilant, but I have one key issue that I would like to discuss here.

I have read about people setting up a MLT that has a re-circulation pump that pumps wort from the bottom of the MLT through a small tank, that contains an element, and then back to the top of the MLT. The idea is that you fill your MLT with the crushed grains, then you can set a timer for it to start. When it starts, it heats up a kettle full of water to the temp you will need for your first rest, then dumps the right amount into the MLT. Then the pump re-cirulates wort around and around, heating if necessary to maintain temp or increase temp. The temp sensor is just after the tank with the element, so you will not get the wort being over heated, and damage being done to the enzymes, but it will also take some time to reach your next rest temp.

This all sounds great, but I have one fairly serious problem. Unless someone is there to dough in the grain at the beginning, the water can circulate around and around, but I think that there will remain some dry spots in the grain which will result in bad efficiency. And I'm not even convinced that with doughed in grain that it will wet the grains evenly...I think the lack of stirring/agitating is potentially a serious problem.

So here is an alternative plan...

I am not sure if you guys have seen these things, but you can buy what looks like a big auger, it fits into a drill and you can use it to mix up paint, render, or small quantites of cement. These things are about 20cm (8in) in diameter amd about 20cm long. So when they rotate in fluid they will push it all up or down depending on which way it goes (I wish I had a pic). Anyway so I was thinking of installing on of them in the centre of my MLT, which incidently is about 100-110L or just under 1bbl. So when the water goes in, it will mix it all up. When its running I am invisaging the auger pulling all the grains up through the middle then they will all get pulled down the sides by motion of the grains at the bottom being dragged upwards, so it will be all homogenous fairly quickly. This way I could program it to do step mashing with mutliple infusions, and there is no need for a recirculating pump to be used before lautering.

I am a little concerned about the well being of the grain husks as I dont want to destroy them by excessive mixing.

I am hoping to start an open discussion here about how people get the temperature distribution in their mash even using automatic processes. I am particularly interested in anyones info that comes from large scale or commercial breweries, as what I am doing here is a bit of a prototype to my future brewery....which hopefully should one day take of the world because it will be so BIG.

Thanks

Pip

Beermaker 08-06-2007 07:23 AM

I am fairly automated. I do the initial dough - in phase, and stir the grains into the water slowely until it is well mixed. After that, I let the solenoids and controllers take over. I thought of using an ice cream mixer with a paddle on it for the mash, but this will keep the grain bed mixed up, and you need the grain bed to compact down to act as a filter for the trub going into the boil kettle. If you keep it stirred up, it will never clear up and filter out before you send it to BK. At least thats how I do it.....

nabs478 08-06-2007 11:16 AM

Quote:

Originally Posted by Beermaker
I am fairly automated. I do the initial dough - in phase, and stir the grains into the water slowely until it is well mixed. After that, I let the solenoids and controllers take over. I thought of using an ice cream mixer with a paddle on it for the mash, but this will keep the grain bed mixed up, and you need the grain bed to compact down to act as a filter for the trub going into the boil kettle. If you keep it stirred up, it will never clear up and filter out before you send it to BK. At least thats how I do it.....

So after you dough it in, you put it all into the MLT (do you have a single mash-lauter tun, or one mashing tun and one lauter tun?), and then infuse water into it to achieve your temp rests? No stirring? Do you re-circulate the water to mix up the temp, or just chuck it in and leave it?

What efficiency do you get?

At the momebt I manually stir my mash quite vigorously to distribute th hot water evenly after infusions. It takes about 5-8L of wort to be circulated (in a batch of 30L) before it runs clear, but it's not a major problem. I guess with this type of stirring I am talking about there will be a lot more debris when the lauter is started.

wild 08-06-2007 11:57 AM

Beermaker is right. Stirring the mash after initial dough-in is bad. If you have a recirculating system, you don't have to stir the mash. In fact, if you stir, you undo 33% of the benefits of a recirculating system. Take a look at this.

Wild

mr x 08-06-2007 01:08 PM

I am working on a stirrer for my steam heated MLT. Vacation is messing with my progress, but I am probably going to use going to use a windshield wiper motor to do the job. I definitely want my mash stirring when I inject the steam.

Llarian 08-06-2007 06:18 PM

Gentle agitation is fine, that's what's used in pretty much all large brewery systems. However, it sounds like you're talking about moving the entire mash at once (if I'm reading that correctly as a closed auger). Most mash agitation is fairly slight blade-like rakes to keep the temperature even across the mash in a large vessle. (I think they're mostly found on 15bbl+ systems)

-D

Monster Mash 08-06-2007 06:34 PM

I agree, unless you have a fairly large system constant agitation is not necessary. I've automated my system also to maintain temps and adjust temps automatically but everything is post mash in.

I do have timers to turn the system on and heat thing up before I'm ready to brew but I still mash in at the correct temp and then let the system take over.

Constantly stirring will just make it more difficult to get a clear run off.

Bellybuster 08-06-2007 07:51 PM

I mash in with a fan blade on a threaded rod turned by a drill. Takes 30 seconds to mash in. I actually had to adjust my strike water down to make up for the less time stirring Then my external heat exchanger keeps the mash at +- 1 deg with recirculation thruout the entire mashing process.
I'm a firm believer that constant agitation thruout the mash is the answer, stop the agitation for the last 5 min for a clear runoff and Bob's yer uncle. I have yet to put together my stirring system but it will come.
My set and forget external heat exchanger is awesome. makes it easy to duplicate beers exactly....not that I've ever attempted that

nabs478 08-07-2007 11:40 PM

Thanks guys, I'll have to re-think my plans

Yuri_Rage 08-07-2007 11:50 PM

I use a steam system with a bit of automation. I find that I get hot spots very easily unless I stir during heating. I use a drill with a paint mixer attached, and I've noticed no problems. I just make sure that I quit stirring about 20 minutes prior to the sparge. Just before sparging, I use a March pump to recirculate the mash until it runs clear.

I average 80% efficiency and have been pretty happy with the system overall.


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