Are cooler size/grain bed depth factors for efficiency?

[grrickar]

So I have exclusively used a 10 gallon sideline cooler for all-grain. With higher gravs, the grainbed can be quite tall (deep). I have tried batch sparging and fly sparging but have found that the efficiencies always seem to disappoint.

I am curious - would a longer/wider cooler distribute the grain bed better and thus allow the sugars to drain more efficiently - all else being equal?

I line the cooler with a wilserbag, but I still vourlaft a few times, and when the runnings start to taper off I stop the sparge, stir the heck out of it, vorlauft and then restart my sparge. The gravity of the runnings typically goes up, so that tells me some of the sugars are trapped in the grain bed (regardless of whether I fly sparge or batch sparge)

 

[stpug]

I would definitely think that grainbed depth can have some effect on efficiency, probably in the range of a couple percent. Negligible in my opinion. High gravity beers (large amounts of grain) will have a larger effect, I would think. But, crush would be where I would start.

 

[sloanfamilydsm]

I think it has more to do with water to grain ratio. I have a 5 gal igloo & 11 lbs of grain seems to be the maximum while still getting acceptable efficiency. Again, consistent grain crush assumed

 

[sloanfamilydsm]

oops, didn't answer the original question.
As to draining the sugars more efficiently, I say no.
Horizontal or vertical I don't think it makes a difference

 

[brewkinger]

I have to go with CRUSH as the factor that most influences efficiency.
IMHO, I think that shape would only be a viable factor if you were fly sparging.
If I had a rectangular cooler, I would batch sparge.

 

[doug293cz]

When batch sparging, the only effects on efficiency that shape could have would be due to differences in grain absorption and undrainable MLT volume. If the gal/lb absorption goes up, then efficiency goes down. Likewise, if undrainable volume goes up, efficiency goes down.

With fly sparging it's difficult to say, as the shape/grain bed depth could affect the how well the grain is rinsed.

Larger grain bills will have lower efficiency just because the total volume of wort absorbed by the grain will be higher.

Brew on

 

[grrickar]

Thanks for the answers guys. I guess some part of me sees that tall stack of grain as too good of a filter to thoroughly rinse the sugars out; especially when fly sparging. I don't see me changing anytime soon from my equipment, but anytime I miss an efficiency to the low side it hurts...

 

[blizz81]

What sort of pre-boil volume are you going with when you batch sparge on bigger beers?


I've found that if I stay close to a batch sparge volume being around the same volume as my first runnings, that I'm able to attain my usual brewhouse efficiency. Of course, on big beers, this can mean I'm starting with 10gal preboil to end at 5.5-6gal in fermenter / means a long boil.

 

[Denny]

I would definitely think that grainbed depth can have some effect on efficiency, probably in the range of a couple percent. Negligible in my opinion. High gravity beers (large amounts of grain) will have a larger effect, I would think. But, crush would be where I would start.

Not if you batch sparge. If it does, then your batch sparge method needs work.

 

[logdrum]

What steps can be taken to improve one's batch sparging method? My final runnings are @ about 1.040.

 

[stpug]

Not if you batch sparge. If it does, then your batch sparge method needs work.

In a perfect world, I would agree with you, but this world ain't perfect

It's fairly common for large grainbill (i.e. high gravity) beers to suffer some efficiency loss for numerous reasons. A high gravity, all malt beer also tends to have a deeper grain bed depth than a standard or low gravity beer. Boiled down (pun intended): grain bed depth affects efficiency, negatively.

The numerous reasons why this happens are an important topic, IMO, as the effects of efficiency loss on high gravity beers can be minimized/negated but the efforts involved may not be worth the endeavor.

 

[Denny]

In a perfect world, I would agree with you, but this world ain't perfect

It's fairly common for large grainbill (i.e. high gravity) beers to suffer some efficiency loss for numerous reasons. A high gravity, all malt beer also tends to have a deeper grain bed depth than a standard or low gravity beer. Boiled down (pun intended): grain bed depth affects efficiency, negatively.

The numerous reasons why this happens are an important topic, IMO, as the effects of efficiency loss on high gravity beers can be minimized/negated but the efforts involved may not be worth the endeavor.

All of which would matter if you were fly sparging, i.e. rinsing the sugar from the grain. But when you batch sparge, the sugar is dissolved in the mash liquor so you drain, not rinse. In that case grain bed depth does not matter. One primary reason you lose efficiency on higher gravity beers is because you don't use enough sparge water, not because of the grain bed depth. This of course requires a longer boil, which as you say may or may not be worth it.

 

[stpug]

All of which would matter if you were fly sparging, i.e. rinsing the sugar from the grain. But when you batch sparge, the sugar is dissolved in the mash liquor so you drain, not rinse. In that case grain bed depth does not matter. One primary reason you lose efficiency on higher gravity beers is because you don't use enough sparge water, not because of the grain bed depth. This of course requires a longer boil, which as you say may or may not be worth it.

Fly sparge = rinse sugar from grain
Batch sparge = drain dissolved sugar from mash

I don't agree that what is taking place between when one is fly vs batch sparging is as simple as you've laid out. Are the sugars not "dissolved" in the mash when fly sparging? Are we not "rinsing" the excess sugars from the mash when batch sparging? This is a point that has been brought up many times before (batch vs fly, dissolved vs rinsing), and I am still not convinced that the differences are all that great aside from the disturbance of the grainbed. Another topic for discussion, IMO.

What constitutes "enough" sparge water? And, at what point is the sparge water amount so much that the boil length would be excessively long so as to negate the effort required. If the boil length becomes so long that it's not worth the effort for some "missing" sugars then we can back off the approach and accept some extract loss, at which point we could say that the grainbill (and by association, the grainbed depth in a round water cooler) caused a loss of efficiency.

 

[wardens355]

Boiled down (pun intended): grain bed depth affects efficiency, negatively.

Eh? I don't see how. A mash tun that has a larger surface area would have a shallower bed, and likely have a larger dead space volume, resulting in lower efficiency. Why would the height of the grain bed matter? You have posted that it does, but not provided reasoning as to why. I think other factors affect the efficiency problem with high-gravity beers, particularly grain absorption and runoff volume relative to grain amount.

I would imagine tall and skinny would be better for fly sparging so you get better water-grain contact.

 

[doug293cz]

All of which would matter if you were fly sparging, i.e. rinsing the sugar from the grain. But when you batch sparge, the sugar is dissolved in the mash liquor so you drain, not rinse. In that case grain bed depth does not matter. One primary reason you lose efficiency on higher gravity beers is because you don't use enough sparge water, not because of the grain bed depth. This of course requires a longer boil, which as you say may or may not be worth it.

I'd rephrase the red highlighted sentence to say: "The reason you lose efficiency on higher gravity beers is because the larger amount of grain retains more sweet wort, so less of the available sugar makes it into the BK. You can compensate for this by using more strike and/or sparge water, and then boiling for a longer time."

Below are batch sparge simulations for a low gravity beer (10 lb grain bill) and a high gravity beer (20 lb grain bill). The simulation assumes 0.12 gal/lb apparent grain absorption, 0.125 gal undrainable MLT volume, boil off of 1.25 gal/hr, target post-boil volume of 5.5 gal, and a 1 hour boil (which gives a target pre-boil volume of 6.75 gal.)





In the 20 lb batch, the mash contains twice as much sugar as for the 10 lb batch. But, the sugar retained in the mash after initial run off is 2.9 times as much (8.01 lb vs. 2.77 lb.) After the sparge, the sugar retained in the mash is 4.2 times as much (4.17 lb vs. 0.99 lb) for the 20 lb batch. Only the retained sugar after the final sparge affects the final efficiency.

The following simulation shows what would be required to increase the efficiency with a 20 lb grain bill to that of the 10 lb grain bill.



In order to get the same efficiency for the 20 lb grain bill as the 10 lb grain bill with a single batch sparge, the total brewing water needs to increase from 8.08 gal to 15.53 gal, and the pre-boil volume goes from 6.75 gal to 13 gal! The boil time would increase to (13 - 5.5) / 1.25 gal/hr = 6 hrs. again. Clearly this is not a viable option.

Even going to a 2 hour boil (8.0 gal pre-boil volume), and two sparge steps for the 20 lb grain bill won't get us efficiency equivalent to the 10 lb grain bill.



Brew on

 

[wardens355]

Brew on

Nice graphics. More water split up into more rinses will yield better recovery of sugars. I prefer to just use more grain because sparge/drain/sparge/drain/sparge/drain makes me go crazy.

 

[stpug]

Eh? I don't see how. A mash tun that has a larger surface area would have a shallower bed, and likely have a larger dead space volume, resulting in lower efficiency. Why would the height of the grain bed matter? You have posted that it does, but not provided reasoning as to why. I think other factors affect the efficiency problem with high-gravity beers, particularly grain absorption and runoff volume relative to grain amount.

I would imagine tall and skinny would be better for fly sparging so you get better water-grain contact.

It was posted before the quote you took out of context

It's fairly common for large grainbill (i.e. high gravity) beers to suffer some efficiency loss for numerous reasons. A high gravity, all malt beer also tends to have a deeper grain bed depth than a standard or low gravity beer. Boiled down (pun intended): grain bed depth affects efficiency, negatively.

More grain makes for a deeper grainbed. Doesn't matter the size or shape of the mashtun. The grainbed depth likely isn't the important factor in efficiency loss, it's the amount of grain used and amount of brew water used. BUT, when we are talking about high gravity, all malt beer we are talking about deeper grainbeds as well - thus the "boiled down" quote above.

 

[doug293cz]

Nice graphics. More water split up into more rinses will yield better recovery of sugars. I prefer to just use more grain because sparge/drain/sparge/drain/sparge/drain makes me go crazy.

For high gravity beers, you are pretty much forced to use more grain to make up for efficiency loss, as even doing multiple batch sparges won't get you to the same efficiency as low gravity beers.

Brew on

 

[wardens355]

It was posted before the quote you took out of context



More grain makes for a deeper grainbed. Doesn't matter the size or shape of the mashtun. The grainbed depth likely isn't the important factor in efficiency loss, it's the amount of grain used and amount of brew water used. BUT, when we are talking about high gravity, all malt beer we are talking about deeper grainbeds as well - thus the "boiled down" quote above.

I can quote your whole post and still have the same comment.

 

[Denny]

Nice graphics. More water split up into more rinses will yield better recovery of sugars. I prefer to just use more grain because sparge/drain/sparge/drain/sparge/drain makes me go crazy.

I've done it that way and found not enough difference to justify the extra effort. YMMV.

 

[mmacdon3]

Eh? I don't see how. A mash tun that has a larger surface area would have a shallower bed, and likely have a larger dead space volume, resulting in lower efficiency. Why would the height of the grain bed matter? You have posted that it does, but not provided reasoning as to why. I think other factors affect the efficiency problem with high-gravity beers, particularly grain absorption and runoff volume relative to grain amount.

I would imagine tall and skinny would be better for fly sparging so you get better water-grain contact.

I've been pondering this as well while trying to troubleshoot my efficiency problems. Why would a larger mash tun automatically have more dead space volume? I have basically the opposite of this situation...I have a large rectangular cooler (70 quart) that I use to mash/batch sparge.

When I do smaller batches I wonder if the extra shallow grain bed depth effects my efficiency at all? I know grain crush is probably the number one culprit but I do wonder if the setup of my equipment plays a part as well.

 

[wardens355]

I've done it that way and found not enough difference to justify the extra effort. YMMV.

Yeah. I used to do two sparges to increase efficiency. Now I either do just one, or two if my mash tun cannot hold the water required for full batch volume. 10-15% hit in efficiency, but less headaches.

 

[doug293cz]

...

I would imagine tall and skinny would be better for fly sparging so you get better water-grain contact.

Looking for something else, I stumbled across the following from The Oxford Handbook of Food Fermentations edited by Charles W. Bamforth, Robert E. Ward:

​

You can find it here: https://books.google.com/books?id...onepage&q=thermal degradation amylase&f=false

So, apparently industrial brewing practice is to use shallow and wide grain beds for fly sparging. This would imply (but not prove) that experience has shown that shallow grain beds lead to more efficient lautering when fly sparging.

Brew on

 

[wardens355]

I've been pondering this as well while trying to troubleshoot my efficiency problems. Why would a larger mash tun automatically have more dead space volume? I have basically the opposite of this situation...I have a large rectangular cooler (70 quart) that I use to mash/batch sparge.

When I do smaller batches I wonder if the extra shallow grain bed depth effects my efficiency at all? I know grain crush is probably the number one culprit but I do wonder if the setup of my equipment plays a part as well.

Your false bottom opening or braided inlet has a certain height from the bottom of the tun (depends on system). A tall skinny mash tun will have less surface area, while a wide, shallow mash tun will have more surface area. For the same height to inlet, the wide, shallow mash tun will have more dead space volume. Shouldn't be that big of a hit on efficiency unless you have a lot of dead space.

The extra shallow grain bed should not make a difference for extraction. The same amount of sugar should be extracted no matter the grain bed depth. I would focus on crush, pH, temperature, mash/sparging process.

 

[Denny]

Yeah. I used to do two sparges to increase efficiency. Now I either do just one, or two if my mash tun cannot hold the water required for full batch volume. 10-15% hit in efficiency, but less headaches.

Wow, that's a lot. I never found more than a 1-2% difference.

 

[wardens355]

Wow, that's a lot. I never found more than a 1-2% difference.

I usually get a 10% or so hit if I do a no sparge process. Mash, then mashout, do a single runoff. That is where I lose efficiency.

 

[wardens355]

So, apparently industrial brewing practice is to use shallow and wide grain beds for fly sparging. This would imply (but not prove) that experience has shown that shallow grain beds lead to more efficient lautering when fly sparging.

Brew on

I think my problem is that this assertion and the earlier one about normal vs. high-gravity mashing have no real reasoning behind them.

A batch with more grain obviously has a deeper grain bed, but the reasons for decreased efficiency are related to the amount of water used, not the grain bed depth. Assuming everything is the same (amount of grain, dead space, grain absorption, water volumes, etc etc), you should get the same general efficiency with a rectangular cooler as a taller cylindrical cooler for the same normal gravity beer recipe. If grain bed depth made a difference for efficiency, you could never get as good of efficiency with a taller mash tun.

The source you quote above says nothing about grain bed depth and efficiency (sugar extraction). It is a leap to just assume that is the reason controlling that choice of depth. The only source I have seen talking about depth talks about high-speed lautering and the lauter tun grain depth being shallower than a single infusion process. I would argue the speed factor makes more sense, because a deeper grain bed will be more prone to compacting and will also have more head loss, so you cannot lauter as quickly, hence the selection of a shallower bed in that situation. Palmer also notes the benefit of a deeper bed is that you get more uniform rinsing (better water-grain contact).

Mash Space

Sorry if I come off as combative, I just don't think people should get the wrong idea about grain bed depth unless there is sound reasoning as to why a shallow bed would be more efficient for sugar extraction.

 

[doug293cz]

I think my problem is that this assertion and the earlier one about normal vs. high-gravity mashing have no real reasoning behind them.

A batch with more grain obviously has a deeper grain bed, but the reasons for decreased efficiency are related to the amount of water used, not the grain bed depth. Assuming everything is the same (amount of grain, dead space, grain absorption, water volumes, etc etc), you should get the same general efficiency with a rectangular cooler as a taller cylindrical cooler for the same normal gravity beer recipe. If grain bed depth made a difference for efficiency, you could never get as good of efficiency with a taller mash tun.

Correct when batch sparging. For batch sparging, the grain bed depth has nothing to do with efficiency. Conversion efficiency is independent of the MLT geometry. For a constant pre-boil volume, lauter efficiency is dependent only on total grain absorption (lbs * gal/lb), MLT undrainable volume, the number and volume of run-off cycles, and whether or not the wort is uniform concentration prior to run off (i.e. in equilibrium.) For larger grain bills, the run-off volume is the same, but a higher wort volume is absorbed in the grain (since there is more grain.), so a larger percentage of the total available sugar is held in the wort absorbed in the grain. The larger the percentage of sugar held in the MLT, the lower the efficiency. The loss of efficiency is due totally to the increased grain absorption, and is unaffected by the higher SG of the wort.

Fly sparging is much more complex to analyze than batch sparging (I haven't been able to find any attempts at modeling and simulating fly sparging.) For batch sparging, you can't reasonably add enough additional water or sparge steps to make up for the loss of efficiency that comes with larger grain bills. I can't say definitively whether the same holds true when fly sparging.

The source you quote above says nothing about grain bed depth and efficiency (sugar extraction). It is a leap to just assume that is the reason controlling that choice of depth. The only source I have seen talking about depth talks about high-speed lautering and the lauter tun grain depth being shallower than a single infusion process. I would argue the speed factor makes more sense, because a deeper grain bed will be more prone to compacting and will also have more head loss, so you cannot lauter as quickly, hence the selection of a shallower bed in that situation. Palmer also notes the benefit of a deeper bed is that you get more uniform rinsing (better water-grain contact).

Mash Space

Sorry if I come off as combative, I just don't think people should get the wrong idea about grain bed depth unless there is sound reasoning as to why a shallow bed would be more efficient for sugar extraction.

I hadn't considered the rate possibility. The lauter tun needs to keep up with the mash tun, so if it needs a shallower bed to do that, then that would explain why they are designed that way. Although, if there were a significant efficiency benefit to deeper grain beds it's possible that having multiple lauter tuns per mash tun could have a positive ROI.

Fly sparging is a complex, dynamic process, so in the absence of validated simulation models for fly sparging, I would discount Palmer's assertion as speculation.

Brew on

 

[Denny]

I usually get a 10% or so hit if I do a no sparge process. Mash, then mashout, do a single runoff. That is where I lose efficiency.

Ah, maybe I misunderstood...I thought you were talking about the difference between one and two sparge additions.

 

[blizz81]

For batch sparging, you can't reasonably add enough additional water or sparge steps to make up for the loss of efficiency that comes with larger grain bills.

I dunno - I've done two or three big beers (last one being a 24.5lb imperial stout, 1.122 @ 5.2 gallons) where I haven't jacked the strike water way up like your simulation chart...I had 8.53gal of strike (my normal 1.25 ratio + vol under false bottom - 0.875gal) for about 5.7gal FR, jacked preboil volume up to 10gals which put me at a single batch sparge infusion of 4.30gal.

Obviously a little off 5.7gal, so I was expecting a bit of a hit still. BeerSmith calc'd a 73.3% brewhouse efficiency, where I normally get 76-80%. 10gal put us at a 3 hour boil, I guess some people might call that "unreasonable". If I remember from what we collected into bottles in the end, I may have measured a shade low on vol in fermenter too, but didn't write that down on this batch.

Had a barleywine with similar results starting w/10gal preboil to end with 5.5gal in fermenter. I don't know if things are as patently dire as the simulations may lead us to believe, but they're maths, and I'm an imperfect hooman, so maybe I'm wrong somewhere along the line. Don't have preboil gravity readings / extract eff #s for those batches.

 

[doug293cz]

I dunno - I've done two or three big beers (last one being a 24.5lb imperial stout, 1.122 @ 5.2 gallons) where I haven't jacked the strike water way up like your simulation chart...I had 8.53gal of strike (my normal 1.25 ratio + vol under false bottom - 0.875gal) for about 5.7gal FR, jacked preboil volume up to 10gals which put me at a single batch sparge infusion of 4.30gal.

Obviously a little off 5.7gal, so I was expecting a bit of a hit still. BeerSmith calc'd a 73.3% brewhouse efficiency, where I normally get 76-80%. 10gal put us at a 3 hour boil, I guess some people might call that "unreasonable". If I remember from what we collected into bottles in the end, I may have measured a shade low on vol in fermenter too, but didn't write that down on this batch.

Had a barleywine with similar results starting w/10gal preboil to end with 5.5gal in fermenter. I don't know if things are as patently dire as the simulations may lead us to believe, but they're maths, and I'm an imperfect hooman, so maybe I'm wrong somewhere along the line. Don't have preboil gravity readings / extract eff #s for those batches.

Ok, I ran your grain wt and strike & sparge volumes thru the simulator. It comes up with 79% mash efficiency (assuming 100% conversion eff.) So, a 73.3% brewhouse efficiency is reasonable if you have low kettle losses.



The "dire" numbers came from trying to get the same mash eff (87%) for a 20 lb grain bill as for a 10 lb grain bill at the same pre-boil volume. If you are willing to accept the lower eff with large grain bills, then you can keep your pre-boil volumes more reasonable. (But personally, I wouldn't be thrilled about a 3 hour boil.)

Brew on