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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
  Analysis of continuous sparge / Just what is "efficiency" anyway? (David Harsh)
  rre: RE: continuous sparge analysis ("steve.alexander")
  Re: Mash Viscosity (Ricardo Cabeza)
  Reading Kunze Carefully ("Dave Burley")
  batch vs continuous sparge efficiency ("William Frazier")
  Re: reply regarding analysis (Denny Conn)
  My Efficiency problem.. fixed? ("Michael Eyre")
  mashing and sparging, time and efficiency (Matt)
  Kunze on batch vs continuous sparge efficiency (Bill Velek)
  WLP099 Yeast? ("Dave and Joan King")


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Date: Fri, 7 Oct 2005 00:00:31 -0400
From: David Harsh <dharsh at fuse.net>
Subject: Analysis of continuous sparge / Just what is "efficiency" anyway?

Greetings-

In HBD #4863, steve.alexander wrote:
> David Harsh <dharsh at fuse.net> writes:
>>> "S/2 case":
>>> Step 1: remove S/2 of the original mash water. <snip>
>>> Step 2: After equilibrium, we again replace S/2 of the liquid.
>>> <snip>
>>> Drain: Finally we drain the (M+X-U) volume of liquid
>>
>> What is described here is a sparge process where the grain bed is
>> continuously stirred
>
> No Dave there is no stirring.

Of course not.  You cut out my words that said "analagous to a mixed 
tank reactor".  The analogy is valid because you are assuming uniform 
conditions within the grain bed.  In process engineering, the model is 
assumed to be uniformly mixed.  So, if you include that assumption, 
your calculations are accurate.  But there is no stirring, as you say.

> Of course this simple model doesn't account for the concentration 
> differences between the top & bottom of the grist bed, but with 
> shallow beds I doubt this factor changes the outcome.   In fairness we 
> should also point out that fly sparging extracts more from the top of 
> the grist heap and less from the bottom, and suffers in comparison to 
> the uniform extraction of batch.

So you are saying that
1.  there are concentration differences throughout the bed, but they 
don't affect the modelling.
2.  concentration differences throughout the bed produce an inferior 
extract

These are major assumptions.  #2, of course, is the reason the debate 
exists to begin with.  It just seems ironic that the assumption that 
caused the debate to begin with is contradicted by the basic assumption 
of your model.

> When we devolve to the point of voting on facts I'll keep your 
> unsupported opinion in mind.  You'll be pleased to read that 
> professional brewing texts disagree with your opinion.  My crude model 
> disagrees with your opinion.  In fact no credible evidence has yet 
> been presented supporting your opinion.    Support it with something 
> thoughtful or talk to the hand.

My unsupported facts?  Please.  Your crude model doesn't describe the 
physical system accurately - so there's a lack of evidence all around.  
Two major assumptions, equilibrium and uniform bed conditions, are made 
and neither is supported.  Equilibrium isn't addressed and 
concentration profiles are dismissed with the wave of a hand.  As I 
have previously stated, a differential analysis of the bed is necessary 
to accurately depict the physical picture and until I see a model that 
accurately describes the real system, I will reject it as inaccurate.  
Likewise for unjustified assumptions.

The problem with your crude model is that as the amount of water added 
and removed becomes smaller, the system describes (in exact detail) a 
stirred tank reactor since you have imposed the uniform concentration 
condition.  And yes, you derived the precise functional form for the 
outlet concentration profile in response to a step change in input for 
a continuous stirred tank reactor.  So 10 out of 10 for mathematical 
rigor, but a big zero on picking the correct model for the process.  A 
packed bed is not a stirred tank.

Here's two issues that must be answered (i.e., proven to not be a 
factor) if they are to be ignored:
1.  If flow is very slow, equilibrium can be reached, but in that case 
the term for axial dispersion must be considered.
2.  If flow is very high, axial dispersion may be neglected, but then 
equilibrium is not reached.
	Source:  Hines and Maddox, Mass Transfer Fundamentals and 
Applications, Prentice Hall 1985, Section 14.4
(and of course, for the "in between" case, both must be considered)  
And "flow" refers to rate of sparging.

The quote from Kunze is interesting.  If there's data to support this, 
by all means present it!   It contradicts all published chemical 
engineering literature (such as Hinds), but I'd like to see the data 
used to support the statement.

But Steve, you also said in #4859:
> under the
> assumption that equilibrium is reached.  *If* you
> sparge forever, then a continuous sparge collects
> 5-7% more of the extract into the boiler.

So, your model assumes equilbrium, yet disproves this?  What gives?  
I'm assuming you had a basis for the 5-7% statement.  I find it 
interesting that the megabreweries, who are known to obsessed with 
maximum efficiency, don't batch sparge.  (I hear their yield is pretty 
good.  I've also heard lots of comments on Budmilloors, but grainy or 
astringent has never been one - and we should if continuous sparging is 
really so bad.)  Sparging forever would imply time is not an issue - 
but according to your quote from Kunze, that would make batch sparging 
more efficient.  It can't be a matter of more sparge water volume, 
because then you could get everything by any method.

To prove/disprove either case, we'd need data to generate a 
breakthrough curve for the bed to prove my point.  And we still lack 
that equilibrium data required to run the calcs.  And I'm still not 
sure what we'd learn that isn't already in the process literature.

- -------
That being said.....
The whole discussion started on "efficiency" and I think that the 
modeling details are a confusing the trees for the forest.  We could 
consider "efficiency" to be any of the following:

1.  Maximum extract from grain
2.  Maximum extract obtained per time
3.  Maximum extract obtained per fixed quantity of sparge water
4.  Maximum extract per fixed quantity of sparge water per time
5.  Minimum time (take first runnings and be done with it)

In my system, where the typical batch is 10 gallons of a strong beer 
(OG>1.070), my method stops (continuous) sparging when I have enough 
wort at the proper gravity.  I gladly sacrifice efficiency, as time is 
my most valuable commodity.  And I'll point out that Steve A. said he 
routinely sacrifices efficiency for desired quality.  But for a pale 
ale, I usually get very good efficiency and do not hear complaints 
about graininess or astrigency from colleagues or judges.

Dave Harsh						Cincinnati, OH
Bloatarian Brewing League



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Date: Fri, 07 Oct 2005 07:05:11 -0400
From: "steve.alexander" <-s at adelphia.net>
Subject: rre: RE: continuous sparge analysis

John Oswald states ...


>>So when Steve Alexander describes the continuous sparge as
>>"Now instead of draining this entire amount as in batch
>> sparging...." What???
>  
>

Right, in a continuous sparge one generally does not allow
the free liquid level to drop below the top of grist-bed.
If you do you may get a blocking compaction.  This is true for
both commercial and HB practice (see Kunze quote).

Not draining *any* of the head liquor is a unfair comparison,
except that the result is clearly identical for both methods
up to that point, and diverge according to the model after that
point.  If you prefer, calculate this initial identical withdrawal
from both, then substitute M', X' into the equations and get the
same comparative result for the remainder.  Yes it reduces the
advantage in percentage points or in extract mass, but it can't
reverse the advantage of batch method.



>>Steve's math starts correct but is complicated as written (an
>>Excell spreadsheet is far less confusing).
>  
>

I agree.   Someday we'll be HTML-ized.


>>But his described
>>"continuous" sparging technique is truly a worst case senario
>  
>

No, it's hardly the worst case, but also not the best. I assume a
static equilibrium for the extract gradient which is better than
continuous can really achieve.  You see continuous liquor is initially
at high SG and so there isn't much of an average gradient to extract
the goods.  We do ignore an advantage of continuous which is that
it is removing selectively higher gravity runnings from the bottom,
but in the initial look it seems that this can only cause continuous
to approach batch performance imperfectly and also slowly and never
exceed it.

If you want to argue the real batch advantage is only half as much
as the simple model imples - you may well be right.  I don't see
the advantage switching.


>>Adding the sparge before the initial run is silly.[...]
>  
>

So you'd prefer that I add more difficult to parse math in
order to model region where both systems have identical
performance ?

I'm relatively pleased with the batch model, aside from diffusion,
but continuous has numerous dynamical variables that make a
full analysis quite difficult.  The point is NOT that this
method is 4.7% less efficient than that one, but rather
that the gross features of one method imply less efficiency
than the other.

Also - hopefully you'll recognize that these 5%
type differences are pointless to the Brewer.  Who in his
right mind would buy new sparging gear rather than tossing
an extra 35 cents of grist onto the heap.  Continuous probably
takes less time/effort  and could be more easily automated; 10
minutes off your brew-day is worth more than 5% extra malt.
OTOH a single batch sparge is very simple and is efficient
enough for any HBer. 

Also I'm an advocate of lower efficiency for better tasting
wort, and I believe you should try to keep efficiency down
to 75% or certainly below 80% ... advantage to continuous !


 -S







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Date: Fri, 7 Oct 2005 10:25:15 -0400
From: Ricardo Cabeza <expunged at gmail.com>
Subject: Re: Mash Viscosity

Marc -

Very interesting post on viscosity.  Could you please clarify this statement:

"  3)  Mash-outs are recommended for a couple of reasons.  First, it kills
off the enzymatic action of the wort (mostly).  Why do we care?  If you
want to "fix" the attenuation of the beer reproduceably, then you want the
enzymes dead at the same time frame time after time.  Alpha amylase
can still be a pretty active little molecule at high temps, and can affect
the attenuation during the short time it remains active during the wort's
way to boiling.  "

What confuses me is what the enzymes would act upon.  I thought mashes
were stopped when starch conversion was complete.  Are you saying that
some ungelatanized starch will run through to the boil if no mash-out
is done, and that alpha amylase will act upon those "run-through"
granules when they gelatanize pre-boil?

The other thing that confuses me is that you state that the
gelatanization temperature for malt and corn generally doesn't exceed
65 C or 149 F (I thought it was higher for raw barley, wheat, oats,
etc., and that's why you buy flaked adjuncts).  So shouldn't the malt
starch be gelatanized already?

CT



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Date: Fri, 7 Oct 2005 11:10:16 -0400
From: "Dave Burley" <Dave_Burley at charter.net>
Subject: Reading Kunze Carefully

Brewsters:

Steve, Steve, Steve, why do you always try to make any discussion personal?
I don't. This is not a battle, don't attack me, just search for truth. And
quoting debating techniques with website references makes all your rhetoric
appear silly.

SteveA (and John Palmer copied me)quoted extensively from Kunze hoping to
prove that continuous sparging was less efficient than batch sparging. 

Sorry.

If you read Kunze <carefully> you will see he is discussing doing a very
<rapid> continuous sparge which we all know (or should because I always say
this)is less efficient than a <slow> continuous sparge.

How do I know this is what he is discussing? Kunze says:

"Of course sparging is rather quicker if it is done continuously, but the
yield is higher if two or three small small sparges are used because the
sparge water then has more time to extract the spent grain contents." 

Kunze goes on:

"When time does not play an important role, because of the higher yield,
sparging is performed in several steps [sja- batches]".


Kunze says that the batch sparges he is talking about take longer than the
continuous sparge. Batch sparging, according to Kunze, is used when the
brewer has plenty of time. 

Huh?  I thought the whole point (at least from my reading here)of doing a
batch sparge was that it is faster than a continuous sparge. So Kunze is
talking about doing a <rapid> continuous sparge versus a <leisurely> and
possibly multi-step batch sparge. I agree he could be right under these
conditions.  Kunze fails to explore all potential conditions of continuous
sparging or is just commenting on applications in breweries using a rapid
continuous sparge he is familiar with. 

So there is no mystery here, just a mis-reading of Kunze without asking the
proper questions about the conditions. Also Kunze notes that more and
smaller, leisurely batch sparges produces a better extraction and SteveA
notes that at infinity lots of little batch sparges become continuous
sparging. I agree. 

The logical deduction is, of course, that continuous sparging (if the
equilibrium between the sparge water and the wort inside the grain is
allowed to be established)is more efficient.

Batch sparging is inherently less efficient at removing sugar from a mash
than continuous sparging for the reasons I commented on before. But the
condition, which I noted before, is that the sparge water comes into
equilibrium with the wort contained in the grain. Steve notes that this
could take an infinite amount of time but comments that in practicality it
takes a few minutes and I agree. 

So, slow continuous sparging (about an hour) will produce the best result,
since in normal one or two step batch sparges, even done slowly, the
specific gravity of the sparge water after the extraction will be higher
than the sparge water at the end of a continuous sparge, indicating that the
SG of the wort inside the grain is higher with a batch sparge and the
extraction less effcient.

Keep on Brewin'

Dave Burley



Return to table of contents


Date: Fri, 7 Oct 2005 10:17:46 -0500
From: "William Frazier" <billfrazier at worldnet.att.net>
Subject: batch vs continuous sparge efficiency

John Oswald writes "Adding the sparge before the initial run is silly. It's 
like rinsing in
the clothes washer before pumping out the wash water. Of course it will take 
forever and be less efficient."

I agree but some brewers take batch sparging to the extreme.  A friend does 
no sparge brewing.  He adds all the sparge water to the mash and then just 
drains the mash into the kettle.  Of course, it takes him twice as much 
grain to end up with the same OG in the kettle as my continuous sparging 
process.

So far I haven't seen any real world examples of differences in the amount 
of grain required to deliver the same starting gravity to the kettle, 
regardless of how much potential extract remains in the grain bed, from 
batch versus continuous sparging techniques.  Are there any good examples 
out there?

For batch sparging how many individual sparges are usually required, how 
long do you let the individual batches of sparge water rest with the grain 
before draining and how long is the entire sparging step?

Bill Frazier
Olathe, Kansas USA 




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Date: Fri, 07 Oct 2005 08:31:25 -0800
From: Denny Conn <denny at projectoneaudio.com>
Subject: Re: reply regarding analysis

I appreciate all the scientific analysis, even if it makes my head spin and 
takes me days to fully absorb.  But I'm a practical kinda guy...I try 
different things and find out what works for me.  One thing I've 
experimented with is differing rest times for the batch sparge 
addition.  I've tried everything from 30 minutes, to stirring in the sparge 
water and immediately recirculating and running off.  within the limits of 
my ability to measure, I have found no difference in the gravity of the 
sparge runoff based on length of rest.  Of course, I never discount the 
fact that maybe I'm doing something wrong, but I've performed this 
experiment maybe a dozen times and gotten consistent results.  Theory is 
great, but experience always wins...

         ----------------->Denny

At 11:55 PM 10/6/05 -0400, you wrote:
> > Therefore, IF one waits long enough to reach
> > equilibrium batch sparge will be more efficent. But
> > fly sparging may be more efficient if sparging is done
> > before equilibrium is achieved.
>
>
>Yes, exactly, but the "long enough" is apparently less than 15 minutes
>per batch sparge rest.




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Date: Fri, 7 Oct 2005 09:16:52 -0700
From: "Michael Eyre" <meyre at sbcglobal.net>
Subject: My Efficiency problem.. fixed?

Hello all!

This whole thing about brew house efficiency is fantastic. I know some
are calling for an end to the 'discussion' before it turns into a brawl,
but it really is informative to a lot of the rest of us, brawl or not. A
lot of things to think of in here recently. 

Anyway, I told you all I'd get back to you after the two beers planned
for last Friday were completed using a new crush, as most of you pointed
out that that is what appears to be my problem, based on the description
I gave.
Since we (me and my partner) were doing two beers side by side that day,
we did two new types of crushes, one double rolled at .045 gap and the
other grain was crushed at .065 for the first pass and .035 for the
second pass. The grain looked remarkably similar, but perhaps the husk
was slightly better intact on the second crush method. We used a
rectangle cooler on the first mash and a converted keg on the second,
both with slotted copper tubes for a filter. With the exception of a
slight stuck mash on the second sparge (remember, we batch sparge!) that
was easily fixed, there was no problem with either brew.

In fact, we found record numbers and improvements in efficiency.
Depending on who's doing the calculation, either me or my friend, we
came up with either 77% or 81% efficiency for the Stout we made, and in
the end didn't have enough room in the boiler to collect everything that
might have been available for the beer. We had way too much wort in the
boiler and had to stop there to boil. The Barley wine we made was
difficult to calculate, so we're not sure what the efficiency was,
because we didn't collect everything the grain had to offer for one
beer, and in fact, ended up combining the grain from the stout mentioned
above and making a mixture of mutant beer from the two of them. 

In either case, the lauter was fine and our efficiency is now greatly
improved. It was indeed all in the crush. Thanks to the lot of you who
diagnosed this problem and helped us out from the dregs of 50%
efficiency. 

Mike



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Date: Fri, 7 Oct 2005 09:19:36 -0700 (PDT)
From: Matt <baumssl27 at yahoo.com>
Subject: mashing and sparging, time and efficiency

As far as batch vs. fly sparging goes, I think a key point has been
missed.  I think it was Steve who noted that either method can be used
to extract TOO MUCH sugar from the grain (i.e. to oversparge).  So to
me, the real question is "for a desired level of efficiency and
attenuation, what is the fastest mash/sparge regimen that does not
compromise the beer's quality?"

Other people might seek the least complicated method or the one that
requires the least attention, but probably a lot of us just want to
minimize the time.  Especially those of us who brew in small apartment
kitchens.  Here are some speed related ideas and my thoughts/questions:

1. If Denny Conn is right, and we can run off batch sparges at full
throttle, then I think batch sparging must be MUCH faster than
continuous.  I have been running my nosparge batches off at about 1
qt/minute, for no good reason, but if we can get away with going faster
(still get good filtering and avoid a stuck mash) many of us would want
to.  Can we really do this?  (I'll probably try, regardless.)

2. According to references in posts by Steve in the past, beta-amylase
activity is essentially gone in 45 minutes--or at most in an hour--at
150F.  So why hold a 150F single infusion longer than that, unless you
just want a bit of extra efficiency?  Assume we have a good crush.

3. Suppose we run off the first batch after just 30 minutes, and this
runoff takes 15 minutes.  I think it is true that most of the enzymes
are in the liquid portion of the mash, and so when all of the first
runnings are collected, they will be about as fermentable as they would
be if you took the first runnings at 45 minutes.  True?

4. Suppose you then want to do a batch sparge.  If you had run off the
first runnings at 45 minutes, the remaining stuff in the mash tun would
be about as fermentable as it can get (for a single infusion at 150F). 
But you ran off at 30 minutes, thus depriving the mash of whatever BA
was in those runnings for an average of 7.5 minutes.  Will this
significantly affect the fermentability of the second runnings?

5. Finally, how long do you really have to wait for the batch sparge
water to extract, say, 90% of it's potential before you run it off?

In most of these exponential-type processes, I like to clip the ends,
and I'm sure I'm happier for it.

Matt


		


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Date: Fri, 07 Oct 2005 13:51:33 -0500
From: Bill Velek <billvelek at alltel.net>
Subject: Kunze on batch vs continuous sparge efficiency

In HBD #4863, Steve Alexander continued to discuss the differences in 
efficiency between batch sparging and fly sparging, quoting Kunze, 
"Technology Brewing and Malting".  The quoted comments by Kunze raise a 
couple of additional thoughts in my mind; Kunze is quoted as stating:

"...  Of course sparging is rather quicker if it is done continuously, 
but the yield is higher if two or three small small sparges are used 
because the sparge water then has more time to extract the spent grain 
contents. ...".

Isn't Kunze saying that fly sparging is faster?  I was under the 
impression that batch sparging is supposed to be quicker, overall, than 
fly.  I think that Denny Conn's page http://hbd.org/cascade/dennybrew/ 
states this quite clearly, and I believe I've read it in other sources 
as well, but Kunze seems to me to be stating the opposite.  Perhaps 
Denny would care to comment.

Kunze continues:
"...  The limited mixing [sja- between batch sparges], and therefore 
greater extract difference between the sparge water and the extract 
solution contained in the spent grains, accelerates the washing out of 
the extract (extraction)."

I interpret Kunze's reference to "limited mixing" to mean "limited 
stirring"; is that correct?  Denny Conn's site (above link) describes 
batch sparging as including stirring: "... an addition of sparge water 
is added.  This is stirred into the mash, allowed to rest for a few 
minutes, thoroughly stirred again, ...".  Moreover, it would seem to me 
that more mixing, as in actual recirculation in a RIMS, would logically 
improve extraction due to something for which I don't have a scientific 
label -- but it is essentially the same thing we see with "chill factor" 
and making heat exchanges more efficient by stirring.  In addition, I 
know that I have read somewhere recently that extraction is also due, in 
some part, to "shear", i.e., mechanical movement within the mash, which 
comes from stirring (or "mixing"?).  In fact, although I don't have a 
RIMS, I have been under the impression that they are commonly used to 
continuously recirculate the mash rather than just to step temperature, 
and that at least part of the reason is to improve extraction.  So, what 
is the answer regarding "mixing" or "stirring" -- assuming, of course, 
that it is done without aerating the mash (don't want HSA).

Kunze continues, "Both procedures are used commonly in practice. ..."
For some odd reason, I've been under the impression that almost all 
commercial breweries use fly sparging; is that not generally true?

Incidentally, Denny's webpage indicates that "... extraction rates (for 
batch sparging) ... range from slightly less to slightly more than fly 
sparging."

Cheers.

Bill Velek



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Date: Fri, 7 Oct 2005 21:31:37 -0400
From: "Dave and Joan King" <dking3 at stny.rr.com>
Subject: WLP099 Yeast?

I couldn't get my normal American (Chico) yeast, so I got White Labs WLP099. 
I've made an IPA (O.G. = 1.073, about 80 IBU) with a pint and an Imperial 
Stout (O.G. = 1.083, about 90 IBU), racked onto the yeast in the empty 
primary carboy from the IPA, both are still fermenting, and I mean they're 
going to town!  The former is almost 2 weeks along, 1/2 of that in the 
secondary.  The Imperial Stout is still in the primary, after a week.

I'm getting ready to make an old favorite American Brown Ale, but I'm 
getting concerned.  They claim 80% apparent attenuation, which is only about 
5% higher than I'm used to with Wyeast 1056, but based on the activity I'm 
seeing, I think it'll end up super dry, and my bittering levels will be way 
too high for the malt sweetness left.  I usually get final gravities of 
about 1.016 for the IPA, and 1.021 for the Imperial Stout, but this time, 
I'll bet they'll go much lower.  I'm concerned I'll get 90% apparent 
attenuation, or so, which will really ruin my balance.

>From their website;
WLP099 Super High Gravity Yeast - Supposed to ferment to 25% ABV, 80% 
attenuation, With low gravity beers, this yeast produces a nice, subtle 
English ale-like ester profile. As the gravity increases, some phenolic 
character is evident, followed by the winey-ness of beers over 16% ABV. Most 
fermentations will stop between 12-16% ABV unless these high gravity tips 
are performed:

Any experience with this yeast, suggested recipe corrections ?  TAT

        Dave King, BIER, [396.1, 89.1] Apparent Rennerian 




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