batch sparging and efficiency

Mon Aug 14, 2006 4:17 am

Last night, Denny mentioned that you get the best efficiency in batch sparging if your first wort and the 2nd running are the same volume. Why is that?

Do me it sounds that you get better efficiency when you do more spargings since there will be sugars left in the grain after the 2nd running. Though that may not be desired since your mash PH will sink and you will have to much wort to boil-off, I wondering about his statement since he mentioned it is a theoretical maxium?

Could it be the maximum for only 2 run-offs?

Kai
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Kaiser
 
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Mon Aug 14, 2006 4:45 am

I read somewhere that you get better efficiency with a thicker mash. If this is true, and all the conversion that is going to happened is complete, all that's left is to rinse out the sugars. It seems to me, a more volumnous batch sparge would soluate the fermentables better.

Iv'e compared this concept, and get better eff. (80+), by mashing at about 1.25qts per lb. The problem I've found with this is that in order to get my boil volume, I need 5 gallons or more of sparge water. This make it harder to set the grain bed, and I find myself vorlaufing 3 or more qts. My last batch I did two batch sparge runnings of about 2.5 gallons each. Got awsome eff. Sure, it took longer, but I'm never in a hurry on brewday.

I've only done 8 all-grain batches and am still looking for my sweet spot (ahem...I found THAT sweet spot long ago).
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rich
 
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Mon Aug 14, 2006 4:48 am

I think when he was using the word efficiency there he meant amount of sugars for the water used efficency not necessarily the extraction efficiency.
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bub
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Wed Aug 16, 2006 6:59 am

Another key he mentioned is the total ammount of water sparged with. I think it comes back to this and stirring really, really well. If you batch sparge with 5 gallons all at once, and stir really well, my guess is that it will have the same ammount of gravity units as if you did 2.5 gallons twice. I think the real key is brining the grainbed up to temp. He mentioned batch sparging with as much as 190*F water, and I think this is to get the viscosity to run off all the good sugars. You have to get that grain bed good and hot. I have had ~80% efficiency using a single batch sparge the last couple batches.
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clayof2day
 
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Wed Aug 16, 2006 10:46 am

This might become a very interesting subject to think about. And I want to add the disclaimer that I don't worry about this while brewing, but I'm an engineer and cannot stay away from thinking about it.

Assume the following model for batch sparging:

a container contains a particular volume of concentrated sugar solution. Every time you drain the sugar solution you need to leave a fixed amount of solution in there. Then you can add more to dillute the soultion and drain out the amount of water that you added.

Given a fixed amount of solution to be collected, what sparging strategy will get you the most sugar into your run-off?

Now I know that this is only a rough model for batch sparging, but it should be good enough analyze the problem on a theoretical level.

Kai
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Kaiser
 
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Thu Aug 17, 2006 7:27 pm

Kaiser,

Here's one source for Denny's statement:

http://home.elp.rr.com/brewbeer/files/nbsparge.html

This paper is by Ken Schwartz. Denny mentioned his name in the interview as one of his inspirations/mentors regarding batch sparging. Since you are an engineer, maybe you could post your take on the equations and the equal runoff volume concept.

Alan
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Fri Aug 18, 2006 4:18 am

I think in order to get maximum efficiency you could combine the two methods ...

Do a mash at about 1.3 qt/lb ... when it's ready to dump add some mash-out water (185 ish, maybe higher) so that the mash runoff equals about half of the total pre-boil volume. Then, split the sparge water into a couple of equal batches and do the whole stir, vorlauf, dump thing twice.


That would, in my estimation, get the most of the sugars using the basic batch sparging methodology (i.e., no continuous sparge). However, the simplicity of the whole batch sparge is somewhat lessened with the dual sparges.

In reality, I usually just count on a little less efficiency and and let laziness take its course with a single mash dump and a single batch sparge runoff.
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calvey
 
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Fri Aug 18, 2006 5:26 am

calvey wrote:Do a mash at about 1.3 qt/lb ... when it's ready to dump add some mash-out water (185 ish, maybe higher) so that the mash runoff equals about half of the total pre-boil volume.


That's actually a very good idea calvey. I'm gonna try it my next batch.
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