Author Topic: Efficiency of Batch v. Fly as it Relates to Mash Tun Design  (Read 5920 times)

Offline bspisak

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Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« on: January 06, 2010, 03:57:46 PM »

I have a straight braided line as a manifold in my mash tun and usually batch sparge. I recently used this setup and did a fly sparge and got horrible efficiency. Is it because of my manifold?  I would think fly would give better results then batch on a given tun design, but maybe that's not the case?  Maybe I'm just barking up the wrong tree?

Offline denny

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #1 on: January 06, 2010, 04:05:11 PM »
Yeah, a straight braided line will promote channeling, allowing the water to "drill down" in one spot and only extract the sugars from that one location, leading to lowered efficiency.  If you want to fly sparge, you need a more evenly distributed lautering system.  One of the great things about batch sparging is that it eliminates lauter design as a variable in efficiency.  FWIW, fly sparging is not necessarily more efficient than batch sparging.
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Offline dbeechum

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #2 on: January 06, 2010, 05:53:05 PM »
FWIW, fly sparging is not necessarily more efficient than batch sparging.

Nope, but it's definitely going to attract more women. :) (Ok, that's my bad pun for the day)
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Offline bspisak

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #3 on: January 06, 2010, 07:04:08 PM »
Hi, thanks for the reply.

I understand the principal of channeling and good manifold design for maximal efficiency, but why would batch sparging yield higher efficiency than fly sparging using the same "poor" manifold design?  Wouldn't I get the same channeling no matter which way I sparged? 

Offline MDixon

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #4 on: January 06, 2010, 07:11:01 PM »
Channeling doesn't matter when batch sparging since the runoff is homogeneous. You get the same concentration of sugars with batch sparging in a single draining of the tun from first drop to last. What is of upmost importance with batch sparging is crush. If one has a substandard crush then efficiency will be lower. With fly sparging the most important aspect IMO is mash tun manifold followed by crush.
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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #5 on: January 06, 2010, 07:12:59 PM »
Wouldn't I get the same channeling no matter which way I sparged? 

You might get the same channeling but with batch it doesn't really matter.  When you fly sparge, if all of your sparge water is "channeling", then it never actually rinses the sugars out of that portion of the grist that it doesn't touch.  With batch, since you're going to drain all of the water, you'll drain (and rinse) the water from the non-channeled areas of the grist too.
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Offline bspisak

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #6 on: January 06, 2010, 07:49:28 PM »
Ok, that makes sense (I think. ;-). 

However, it seems that a better manifold design would benefit both batch and fly sparging alike.  Right?

Online Kaiser

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #7 on: January 06, 2010, 10:06:54 PM »
However, it seems that a better manifold design would benefit both batch and fly sparging alike.  Right?

Not necessarily for efficiency but maybe for run-off speed.

What matters in batch sparging more than in fly sparging is the amount of wort that is left in the MLT after each run-off. The more you leave behind the worse your efficiency will be since you leave more extract behind. Most of it will be caused by grain absorption and you can't do much about it unless you squeeze the grain. But some may be caused by dead spaces that you cannot drain fully. That might be the case if your pick-up is above the MLT floor.

Here are a few batch lauter tun designs. A and B are false bottoms. C - E are braids or pipe manifolds:



A is best since you don't have any dead space. E is worst if you stop the run-off as soon as bubbles appear. The case E may happen when the braid floats up.

But don't fret out about it either. If the dead space contributes to less than a pint additional wort absorption it won't make much difference. And in the end, batch sparging lauter efficiency lost is good for the beer since it keeps you from oversparging.

Fly sparging is different because of the channeling problem. There you can have low efficiency and still extract excessive tannins in the channel that formed. And if you don't drain all the wort either you may never give the extract rich wort outside the channels a chance to "fall" into the channel and towards the manifold.

John Palmer did a lot of work on evaluating manifold designs for fly sparging and he dedicated a chapter in How To Brew to that. I did work on evaluating what matters for batch sparging (http://braukaiser.com/wiki/index.php?title=Batch_Sparging_Analysis) and for what it's worth you could batch sparge through a hole in the bottom of a bucket and it can still give you 80+ % efficiency for most beers. But it may take so long that the wort will sour before you are done.

Kai


Offline MDixon

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #8 on: January 07, 2010, 06:13:50 AM »
So long as you can fully drain the tun, then the efficiency of your batch sparge is what it is. The only way you can lower it is by not completely draining the tun. What that says, in a nutshell, is you could theoretically find the lowest point of a tun and drain from that point. So a SS scrubbie covering that point would work - IF - it didn't suck everything to that point and create a very slow flow - stuck mash. As was pointed out, you may speed the flow using a manifold or other method.
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Offline stout_fan

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #9 on: January 07, 2010, 06:46:27 AM »
Kai,
D looks like the best braid technique. A Colman extreme 70 qt happens to be that profile.
I'd say something witty down here, but I'm at a bit of a disadvantage in that department.

Online Kaiser

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #10 on: January 07, 2010, 07:48:48 AM »
So long as you can fully drain the tun, then the efficiency of your batch sparge is what it is. The only way you can lower it is by not completely draining the tun. What that says, in a nutshell, is you could theoretically find the lowest point of a tun and drain from that point. So a SS scrubbie covering that point would work - IF - it didn't suck everything to that point and create a very slow flow - stuck mash. As was pointed out, you may speed the flow using a manifold or other method.

Yes, that is correct. But keep in mind that lautering is not necessarily the best place to chase efficiency. If you are batch sparging and are seeing poor efficiency it is most likely due to incomplete conversion of the mash. The beauty of batch sparging is that its efficiency is not determined by dynamic difficult to control factors but only by static parameters like: wort let in the tun after run-off, number of run-offs and size of run-offs.

Fly sparging doesn’t have the theoretical efficiency limits of batch sparging, which are actually well in the 80s for most beers, but takes more skill and better equipment to be done right. It’s not as easily modeled as batch sparging. John took a stab at it in his book and I assume that there is much more data out there since big brewhouse manufacturers are concerned about that. They want their mash tuns to lauter as efficiently as possible.

Here is a little piece of information that I found a while back. Did you know that the swan-neck design seen on the faucets feeding old lauter grants are there to reduce suction on the grain bed? They are designed such that the opening of the faucet will be at the same level as the false bottom. As a result the wort that is below the false bottom and in the pipes leading to the grant cannot suck on the grain bed since it has to travel up the swan-neck where it looses all that energy. Modern tun designs monitor the pressure in each of these drain pipes and use that to regulate the pump speed as well as the cut depth of the rakes. The latter is also controlled by the clarity of the wort.

D looks like the best braid technique. A Colman extreme 70 qt happens to be that profile.

Yes, that is true. But don’t expect big gains from that difference. Maybe 1-2% would be my guess.

You can check for dead spaces and in efficiencies by calculating the grain absorption A after draining completely:

A = (total water volume used – temp corrected wort volume collected) / grist weight.

It is generally between 0.1 – 0.12 gal/lb. If you’re in that ball park there is not much you can improve. I have had a few cases where the grain retained more and I don’t exactly know why.

Note that A is what I call apparent grain absorption. The true grain absorption is higher since dissolved sugars also contribute to wort volume. But you only have to consider that if you need to know the actual volume left in the grain and not just what appears to be left in the grain. Here is some info on that: True vs. Apparent Grain Absorption

Kai

Offline bspisak

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #11 on: January 07, 2010, 09:24:04 AM »
Thanks Kaiser for putting so much thought and effort into documenting brewing processes and providing a resource for those of us who can't reference the German texts.

So, if I were to compare Batch to Fly sparging, I come up with the following:

1) Assuming a simple tun manifold with no dead space (Figure D), batch sparging can result in higher efficiency than fly sparging.

2) Assuming a false bottom with no dead space (Figure A), fly sparging will always yield better efficiency than batch sparging.

Is that correct?
Brian

Offline denny

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #12 on: January 07, 2010, 09:30:48 AM »
2) Assuming a false bottom with no dead space (Figure A), fly sparging will always yield better efficiency than batch sparging.

Is that correct?
Brian


Nope, not necessarily....at least not in my experience.  There are other variables involved.
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Online Kaiser

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #13 on: January 07, 2010, 10:00:27 AM »
1) Assuming a simple tun manifold with no dead space (Figure D), batch sparging can result in higher efficiency than fly sparging.

Yes. Even with dead space batch sparging can give higher efficiency. Important here is “can” which makes the statement fuzzy again.

Quote
2) Assuming a false bottom with no dead space (Figure A), fly sparging will always yield better efficiency than batch sparging.

No. And that is b/c you used “always”. When we compare efficiencies between the two we have to make sure we talk only about lauter efficiency. This is the efficiency with which soluble extract created in the mash is transferred into the boil kettle. You can make the statement though that the lauter efficiency of a perfect fly sparge (i.e. all wort concentration gradients are always pointing downward) will always be equal or better than a batch sparge (including no sparge). I had to use complicated language about concentration gradients to make that statement. “all wort concentration gradients are always pointing downward” essentially means that there is no channeling and no pockets that don’t get sparged.

In practice these two conditions: same level of mash conversion and completely even draining are not necessarily given and explain why there are many cases where batch sparging outperforms fly sparging in efficiency into the kettle. One controversial statement I have made in the past is this:

"Because there is no concern about channelling in batch sparging batch spargers might be able to mill their grist finer which may give them a more complete conversion in the mash. This additional mash conversion can lead to a greater efficiency into the kettle even if the actual lauter efficiency of the batch sparge is lower than that of the fly sparge"

And I'm standing to this even though it is easily misinterpreted and the becomes rather volitile fuel for the batch vs. fly debate. BTW, I'm so glad that we are over that and are now able to look at both thechniques with a more objective eye.

Kai
« Last Edit: January 07, 2010, 10:07:54 AM by Kaiser »

Offline bluesman

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Re: Efficiency of Batch v. Fly as it Relates to Mash Tun Design
« Reply #14 on: January 07, 2010, 11:04:20 AM »
Kai,

I believe that by agitating the sparge one may acheive a better lautering efficiency. The only concern would be allowing fines to get into the kettle. If the trapped sugars (in solution) inside the grains were able to be mechanically extracted, one would acheive better efficiency. That's assuming there is a significant amount of available sugars to extract which I believe to be true.
Ron Price