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View Full Version : Cold Liquor Tank versus Glycol Loop in Stage 2 of HX?



eoconnor101
07-10-2014, 07:18 PM
What's the general consensus on using a Glycol Jacketed Cold liquor tank versus directly circulating glycol through the second stage of a two stage heat exchanger?

Assuming you use city water first through stage one, to crack down the bulk of the heat, reclaiming that water for your HLT for the next day. But then you have two options for stage two?

It seems like using the CLT allows you to chill the water over 12 hours or so between brew days, so as not to tax your chiller as hard, but what to do with that water? It won't be that hot and I guess you could re capture it in another vessel, pump it back into the CLT and chill it, but it would likely be 80 degrees plus still so require energy to drop it back to 40 degrees or whatever, plus you need another vessel which takes valuable space.

If you use the glycol loop do you run all stop on your other processes? I don't like the sound of that. Or else you need a much larger glycol unit.

Or do people run from the CLT in the first stage set to 55-60 degrees, reclaim that to the HLT and then use the Glycol unit in the second stage? In this scenario maybe the second change in temp isn't as drastic, plus you reclaim all your water. As a bonus you could filter the water into your CLT prior to use so it's both hot and filtered already in your HLT. It would be hard to filter the city water fast enough to knock down the temperature to not stress the Glycol unit, and still get filtered water pre heated into your HLT.

Thoughts, want to get it right the first time, this time.

Starcat
07-10-2014, 08:19 PM
What's the general consensus on using a Glycol Jacketed Cold liquor tank versus directly circulating glycol through the second stage of a two stage heat exchanger?

Assuming you use city water first through stage one, to crack down the bulk of the heat, reclaiming that water for your HLT for the next day. But then you have two options for stage two?

It seems like using the CLT allows you to chill the water over 12 hours or so between brew days, so as not to tax your chiller as hard, but what to do with that water? It won't be that hot and I guess you could re capture it in another vessel, pump it back into the CLT and chill it, but it would likely be 80 degrees plus still so require energy to drop it back to 40 degrees or whatever, plus you need another vessel which takes valuable space.

If you use the glycol loop do you run all stop on your other processes? I don't like the sound of that. Or else you need a much larger glycol unit.

Or do people run from the CLT in the first stage set to 55-60 degrees, reclaim that to the HLT and then use the Glycol unit in the second stage? In this scenario maybe the second change in temp isn't as drastic, plus you reclaim all your water. As a bonus you could filter the water into your CLT prior to use so it's both hot and filtered already in your HLT. It would be hard to filter the city water fast enough to knock down the temperature to not stress the Glycol unit, and still get filtered water pre heated into your HLT.

Thoughts, want to get it right the first time, this time.

Eric your questions are good ones.
Also if your volume is subject to grow, the whole equation changes such as your time to cool down CLT.
Some HX units will allow you to run CL and Glycol together. With that being said, what I advise is having redundancy in your chiller systems, or at the minimum, a 2 stage chiller. That is a 2 compressor system instead of a single compressor unit. Based on what I have seen with much larger operations, having a dedicated chiller for the brewhouse and a separate one for fermentation is simply golden in the way your system performs. We are lucky enough to have 3 separate units - brewhouse, fermentation, and brite with the entire loop system capable of running on any one if necessary. Also if you are cooling a CLT, you can set up a separate standalone DX to water system just to pull that down. We happen to cool CLT with the unit that we knockout with.
All of these matters become time sensitive with respect to load and the efficiency of your cooling units as they will vary with season etc.
When you have this kind of separation of cooling, your Brewhouse activity will not cause your glycol that you need for fermentation to swing high. Alternatively, if you go with a single chiller and install a 2 stage unit with more capacity than needed to start, the second stage will allow you to recover your loop temp quicker after you load it heavy with cooling hot liquor. The other major benefit to a 2 stage system is you can loose one compressor and still have 50% capacity running.
As thus a 2 stage system is quite superior for a single chiller brewery.

The one thing that many do not consider is when their single compressor single chiller is going to be down and for how long.....
There is simply not enough redundancy being built in to most start up operations.
Too many things are being demanded of single chiller systems PERIOD.
If you are without a very qualified Refrigeration Tech when this happens, your product is most likely out the window. This is not to mention the necessary parts to make the repair being close at hand.
In an industrial setting this kind of thing is taken very seriously.
The idea is to have the plant tuned to the point that there will not be any major setbacks with regard to ultra critical systems.

All the best

jimvgjr
07-11-2014, 07:44 AM
I can definitely agree with Warren, on the value of a two stage/compressor chiller system to provide redundancy.

Ideally if a brewery that we work with has a CLT, the objective is to use 35-40 F Chilled Water to cool the Wort in a single section Plate HX from 210 F to 68-70 F. The HX is designed for a 1:1 flow rate with Wort flow vs Chilled Water flow, so in theory they will be replenish the HLT at the same volume used for the previous batch.

I do often see people use both of the other scenarios you describe, city water/ with glycol chill assist or city water/ with CLT for final cooling- especially a brewer doing lagers.

From a Chiller System Standpoint:


Using glycol directly in the second stage of the HX creates a tremendous short term cooling load on the system, often times increasing the temperature of your entire cooling loop and in some cases you will end up using your chilled beer that is being stored in brite or conditioning tanks to assist in bringing the glycol loop temperature down after processing Wort. Often this short term cooling load is actually greater than your entire cellar load- so brewers will simply size the glycol chiller system for the Second Stage Wort Load and during this 30-60 minutes dedicate all of their cooling to the Wort HX.



Using a CLT will take the very high short term load and spread it out over an extended period (essentially you'll have all of the time between brewing batches to cool down the CLT). This enables you to operate with a smaller HP Chiller System.



I'm sure you are more looking for feed back from breweries on this thread, but wanted to throw these points in.

Good Luck,

Jim

eoconnor101
07-14-2014, 02:48 PM
Say the coolest we wanted to get wort down to was 62 degrees for pitching, is this feasible in a single stage chiller running cold liquor at 40 degrees in a 1:1 ratio to reclaim hot water?

What would you think about having a two stage chiller, and only using the glycol in the second stage when trying to drop it to 60-62 degrees?

The chiller will be a four compressor unit with a total horsepower of around 55 HP.

Cheers

Starcat
07-15-2014, 07:22 AM
Say the coolest we wanted to get wort down to was 62 degrees for pitching, is this feasible in a single stage chiller running cold liquor at 40 degrees in a 1:1 ratio to reclaim hot water?

What would you think about having a two stage chiller, and only using the glycol in the second stage when trying to drop it to 60-62 degrees?

The chiller will be a four compressor unit with a total horsepower of around 55 HP.

Cheers

What 2 stage means is a 2 compressor system on a common evaporator, so you need to imagine 2 refrigerant circuits usually staged 2 degrees apart that cool the same fluid in and out to your well. Its not 2 separate glycol circuits. That is achieved with separate units. So if I had a calculated load for my new brewery at 5 HP, I might see if Pro or another outfit could build me a 6 HP 2 stage unit....that is 2, 3 HP compressors. With a 2 stage unit you can have some extra cooling power when needed if you have slightly oversized and then you will only ramp up one stage under lighter load. Also you can lose one compressor circuit and not be completely down. ON your 4 compressor system they run very much the same with controls that stage up and down with respect to load.

jimvgjr
07-15-2014, 01:19 PM
Say the coolest we wanted to get wort down to was 62 degrees for pitching, is this feasible in a single stage chiller running cold liquor at 40 degrees in a 1:1 ratio to reclaim hot water?

What would you think about having a two stage chiller, and only using the glycol in the second stage when trying to drop it to 60-62 degrees?

The chiller will be a four compressor unit with a total horsepower of around 55 HP.

Cheers

Its real feasible thank you could size the Wort HX for this load- but understand the closer the Temperature Difference between the Wort and cooling media (Glycol or Cold Liquor), the more Heat Exchanger Surface Area that will be required (and larger the HX, the higher the cost).

I'd suggest contacting Thermaline http://www.thermaline.com/ and have them run the numbers and provide quotation on this HX.

Not sure I follow on the two stage chiller question, running one chiller at warmer temperatures for the first stage and the second at lower temperature for the final cooling? This is definitely feasible, but why use a chiller system for cooling the first section when you can use city water that needs to be preheated anyway?

Will need some additional information to advise on the 55 HP System you are using. If you'd like to fill out our Brewery Load Survey Form here (http://www.prochiller.com/brewload.html), I'd be happy to run the numbers and let you know what size chiller system we'd recommend.

Good Luck,

Jim

Pro Chiller Systems
jimvgjr@prorefrigeraiton.com

eoconnor101
07-16-2014, 03:45 PM
I'm sorry. I meant a two stage HX not a 'two stage chiller' don't even know what that is. The unit will have four compressors on a common evaporator.

I meant

Stage 1 HX, use cold liquor to knock down (or city water in winter, and have an extra fermenter)
Stage 2 HX, use Glycol if needed, probably need year round for lagers, only summer for ales

Cheers

hosshosshoss
08-21-2014, 11:12 AM
Great information here and thanks for the folks who are providing guidance.

We're currently going through a similar planning process with a slight twist... we have access to a very large chiller, that is currently sitting un-used, in our building that was previously used as a cold-water chiller for an AC unit that cooled the entire 23k sq ft building as well as the refridgeration needs of the super market that was there. We are far from refridgeration experts but we're being told by a few contractors that are that the unit will put out "way more than you guys could ever possibly need". We obviously need to get the thing checked out and get real data on how much "way more" actually is.

In general though... assuming this chiller will more than meet our needs, I'm curious about what a general set-up would look like in order to, if possible, eliminate waste water almost altogether. Our first thought (which I was glad to see on this thread) was to definitely set aside different circuits for fermentation and wort chilling (although brites are a real likelyhood too now that I'm thinking about it).

The system is a 15bll and we do a fairly large number of styles so we will like to go with quite a few 15bbl fermenters (eventually a dozen or even a few more). In terms of brites, we would probably be looking for 3 15bbl brites to cycle through. For the fermenters and brites, I'm curious what a ballpark glycol reservoir might look like in terms of size assuming we can easily keep those resevoirs at least 35 degrees.

Then, on wort chilling, I'm wondering if a "two-tank closed loop" system might work. Have the chiller chill a CLT down to temp in an insulated tank, run that through the heat ex, and then push the run-off into an un-insulated "holding tank" to then be pushed back through the chiller, once it has cooled down a bit, for the next time it is needed.

I understand we would be losing the benefit of heat reclamation for the next batch by not running off into the HLT... and I'm not sure would not ultimately still go with that method... but am just curious if 1) the idea would work and 2) are there any other real negatives to doing it that way.

Thanks and cheers!

Natrat
08-21-2014, 01:24 PM
Hey Brian. Here are some considerations....

I have no idea what a "very large chiller" is in terms of cooling capacity, and your cooling loads will vary depending on what beers you are doing (for instance, if you're doing a fast wit that drops in 3 days and then you crash it as your main, that will use far more load than a lager that you crash and hold for a week as your main) so it's difficult for me to estimate your cooling load. The guys at Pro Refrigeration have a handy survey that calculates a lot of that for you on their website.

Be careful of what the experts tell you, as you would be surprised at how fast you hit "way more than you need" in a brewery. The question is if it can be re-purposed for chilling glycol for a reasonable price. You can run water, but it's far less efficient because you cannot run temps below about 34. If you just add glycol, you may bump up against some equipment failures (propylene glycol degrades and becomes more acidic AND is much higher viscosity than water...which is hard in a system spec'd for a lower centipoise fluid), and bear in mind that the chiller is sized for a delta T for WATER, and the delta T for glycol is greater...again, messing with your capacity calculations.

You are going to have to chill your brights, for sure (unless you use single wall serving tanks in a walk in) since your beer won't hold much CO2 at room temp :-)

The magic number for most glycol systems is 27 F, which (again) is colder than water. Higher temps lead to more compressor cycling and bigger pumps (or over worked pumps) in order to cool a similar amount of beer. Most of us use chilled water for the HX, and recapture the heat in the HL tank for mashing in or process water. Letting it bleed off heat in a tank seems like a waste of energy, unless it's really cold and you need to heat the room! Also, closed systems using water tend to get...stinky. Personally, I think your two tank closed loop sounds like extra money to set up, wasted energy, and more cleaning than I'd want.

Hope that helps.

hosshosshoss
08-21-2014, 01:45 PM
Yes, we'll obviously chill the brites, I was simply saying that I wasn't considering their own dedicated circuit until I read this thread. I was considering one circuit for wort chilling and then another for fermenters and brites... but now I'm considering three circuits.

The only reason I'm considering not reclaiming the heat from chilling wort into the HLT and thinking if some sort of closed loop system would work is that we're on septic... so I'm trying to cut ALL waste water out... or at least as much as possible, since we already have an operating full-pour taproom and opportunity to expand that. We have a great location in a great building, except... septic. There are no sewers in the whole town. We don't want to jeopardize potential future expansion on the tap room because we keep topping out the septic with waste water. If we can chill our wort, reclaim the water in the HLT, and not have any waste, that is the way we would likely go. I'm just seeing if there is another option given our sensitivity to waste water. If it means being a bit less energy efficient, it's not ideal but it is better than overloading the septic system.

I'm not overly concerned about load right now and we're simply going under the assumption (for just this discussion) that the chiller that is in place will be sufficient. We'll certainly go through a lot of work to ensure that it is, etc. and if it isn't, we'll obviously go another route. For right now though, we're simply trying to size reservoirs and get thoughts on potential lay-outs.

lhall
08-22-2014, 08:52 AM
We have a CLT and a one stage heat exchanger. It's not 1:1 - it takes about 50 bbls of 40 F water to cool 40 bbls of wort to 64 F. The resulting hot water is around 170 F going back into the HLT. For multiple batches, you want to size your colt liquor tank's heat exchange surface and your glycol system so that you can chill city water back down to 40 F in the time between knockouts.

The problem we are running into is not enough CLT heat exchange surface, and we can't get 88 F city water in the summer down to 40 F before another knockout.

hosshosshoss
08-22-2014, 09:16 AM
Thanks. That's helpful. For the foreseeable future, I don't see us brewing more than once a day so I would hope the CLT would have enough time to come back down to temp.

We also have the luxury of not having city water at that temp (88 degrees?? dammmmn.. that's warm). We are at about 60 at the hieght of summer and almost 40 in the winter.

In my head, I keep thinking about a 850 gallon CLT to use strictly for chilling wort which from the sounds of it might be a bit overkill for a 15bbl system. That said, just because we have a tank that big, that doesn't mean we have to fill it (and waste energy chilling a full 850 gallons). And, I don't think having the extra space would be a bad thing.

Just thinking out loud... I am wondering if two 850 gallon tanks make sense but not necessarily in a closed loop as I was mentioning before. I've found some tanks that size online at a very reasonable price so I'm not super concerned from a cost perspective. The thought process is: Chill maybe 600 gallons to 40 degrees in the CLT (volume can always be tweaked once the process is run through several times), run that through the heat ex to chill wort out of the BK, run the 'hot' water off into the HLT to reclaim and then any excess go into the "Second CLT". The second CLT is then topped off, chilled overnight and ready for the next batch the following day.

We would be reclaiming the heat, there would be zero waste water (per the septic concerns). There would obviously be the cost of the second tank but again, I'm more concerned with the septic than the expense of one extra tank. I would start to get concerned about cleaning those tanks though I guess. I keep having this thought of stagnant water but I don't know that's a ligitimate issue.

I'm also still curious what size glycol reservoirs folks would typically have for... just round numbers, call it, 10 15bbl fermenters and then 3-4 separate 15bbl brites.

Thanks again.

Tubbybrew
08-22-2014, 09:18 PM
Hi Brian -- Not sure what your plan is to heat water for your HLT but you might find it more economical to use two HLTs and one CLT. During the summer, we need to use a CLT in order to get our wort down to pitching temp. Since we don't use the CLT year round we opted for an economical solution (it's a plastic bulk water tank) that we run city water into through a brazed plate HEX with glycol from our chiller. Takes us about 2.5 hrs to chill ~280 gallons of filtered street water down to 45-50F but it really taxes our chiller.

Like you, I don't like wasting water but unfortunately, the water coming out of our brewhouse HEX is only about 155F which isn't warm enough to use for sparging batch 2 so we typically dump the first batch's cooling water down the drain. If I had the room, I'd have a 2nd HLT (or storage tank) to run that off into which we could then reuse. Our HLT isn't heated directly (it's an insulated stainless tote)... we have to either fill it directly via the tankless h20 heater or run under temp water (already in the HLT) through a recirc loop with our tankless h20 heater to get it up to temp for mashing/sparging. Recirc'ing the tank could take upwards of 3 hrs (depending upon starting temp, volume, etc) to get to proper temp. If I had two storage/HLTs I could alternate between the two and push used/luke warm water from one through the tankless into the other and have all the hot water that I need for mashing and sparging both batches plus water to clean with (the tankless is capable of heating ~4 gal/min to 185) and not have to dump a drop of "clean" water down the drain.

I think trying to reuse cooling water as cooling water again is a huge waste of energy... there is so much heat (energy) in that water after cooling the wort that it takes upwards of 4 days for it to cool to room temp (and that's just 150 gallons), you'd be better off using that warm water for other warm water processes and using new, presumably cooler water from the street for cold water processes.

You're more than welcome to come see the setup next time you're in town and I can walk you through what I'm talking about.

Cheers!
- Chris

hosshosshoss
08-26-2014, 07:04 AM
Hey Chris,
Thanks for the info... much appreciated.

I'm not sure how we're going to structure this just yet but that's helpful info to think about. Our first order of business is really getting this chiller that we've stumbled upon inspected, up and running, and then we need to clearly understand what it'll do. From what we've been told though, it would be a massive chiller compared to the chillers a brewery our size would typically use.

Once we have the real story on this chiller, maybe we can go as far as looking into alternative energy sources (solar perhaps) to cut back on the energy use of running it (just thinking out loud).

Thanks again and we'll likely see you this Friday down at the Seaport.

Cheers,
Brian