Heat Exchanger Questions

[eoconnor101]

I searched and read a few threads on this, but just had a few questions. We bought a 7bbl system that came with a relatively small plate in frame. We figured it was too small so got a second donated to us and figured we would run the first city water against glycol (3HP unit set to 28 degrees) and then that city out against wort in. First try city was at 68 and it took us an hour and 5 minutes to get 230 gallons in at about 85 degrees, problem is glycol was overworked and got up to 65 degrees or so but quickly recovered when we finished. Next we ran the city through a 20 foot by 1/2 inch copper coil in 44 degree ice bath...we were running about 5-6 gallons a minute city, about 4 gpm on the wort which was going in at about 85 again...a slight improvement but only slight, this time our glycol heated up to 58 and then slowed.

Obviously we need a bigger plate in frame, and will probably put a cold liquor tank in the walk in and forget about the glycol, but....

1) I read that the wort valve should be downstream of the HE, does that mean the pump with the valve on the outflow of the HE should all be downstream of the HE?
2) If we use a cold liquor that's pump fed, does that pump and valve also need to be on the output side of the HE? And to get that going if the walk in is a ways away should the CLT be off the ground to gravity feed the HE?
3) If we do use a coil pre chiller (actually going to add a second coil inside the first) in ice what is the ideal flow rate? If we go too fast we aren't getting enough contact time right?, should we use a pump/whirlpool in the ice bucket? But if you don't go fast enough you won't carry enough heat off your wort. How do you optimize the flow rates?

one brewer told us that the cooling water out being hot is good meaning you are taking away heat and another said it doesn't matter what it is in our system, set your city water flow to your glycol units BTU capacity and then adjust wort flow until desired temp into fermenter is reached, but the faster the city flow the better. Should we also dump the plates in an ice bath?

HelP!

[yap]

have you tried running your first HX with wort against city water and then the output wort of that into the second HX running against glycol? That way the bulk of the heat is being taken out with city water and the glycol only has to cool down the last few degrees. This will keep the strain on your glycol system down a bit...

If that works you won't need the coils/ice bath/CLT etc....

I would get a bigger HX before going to the trouble of creating a contraption that uses ice. In the end it'll probably cost you about the same.....

[Ale]

I had to deal with a similar situation and in the end decided to pre-chill the supply water with glycol and use that pre-chilled water in HX 2 to chill the wort. I would never want to have to clean and sanitize 2 heat exchangers every time I brewed, and with used or older HX cross contamination can be an issue, better to get a little water in the beer than glycol/water mix.

As to your other questions, for us we sent liquid every which way and used the most efficient route.

[tomhennessy]

Wort Cooling

We had the same issue and use a second heat exchanger but we do something different. The city water which only goes down to about 71 in the summer goes through the main heat exchanger first, when it comes out of that the water is about 95 which is still a whole lot colder than the wort, so it continues to the second smaller heat exchanger then on to our clean mash tun to be saved for another brew or cleaning. The wort comes out of the kettle into the second heat exchanger and gets pre chilled before going to the main one. This works great and we can transfer 7 bbl's in about 45 minutes.
Good Luck!

Tom Hennessy
Colorado Boy Brewing Co.
602 Clinton St. / PO Box 877
Ridgway, Colorado 81432
970-626-5333

https://www.coloradoboy.com

Author of The Brewery Operations Manual
-3 Steps to Open And Run A Successful Brewery
Available On Our Web Site

[eoconnor101]

I just stopped by a brewery here in town and they too use city water first against wort and then the second exchanger is wort against glycol....but if the glycol heats up just trying to cool the city water with an ice pre chiller I'm wondering if it can handle chilling from say 90 to 70 degrees without being overworked. At this point I really wish I was 'upsold' on a glycol unit. Next brew we'll try city water first. If that doesn't work we'll start looking at cold liquor tanks for our back walk in. I'm guessing you just blast the city water full on in this scenario?

[jimvgjr]

I think you are on the right track, we see customers in the warmer regions (with warm water supplies) go with a Cold Liquor (Water) Tank which is chilled over an extended period of time to 35-40 F. This water is then transferred thru Wort HX at approx 1:1 Flow Rate, allowing them to reuse in next batch or for cleaning (as mentioned before here). We also have customers run the makeup water feeding their CLT thru a glycol HX to prechill as they are filling the Cold Liquor Tank.

Some customers will get their wort to desired temperature using 100% city/well water for 70-80% of the year. During the portion of the year their water supply temperature is too high, they'll run glycol thru a second Heat Exchanger or utilize a two stage HX. They'll still recover the heated water used in the first section for cleaning or in the next batch.

For your scenario the Total Wort BTU Cooling Load is around 280,000 BTU (based on cooling 7 Bbls Wort from 210 F to 70 F).

If you are able to cool the Wort to 90 F using city water, the remaining cooling load (90 F to 70 F) is about 40,000 BTU. The cooling load will drop proportionately, so if you can get the Wort to 80 F using City Water, the load is half, or about 20,000 BTU.

Your 3 HP Chiller System operating at 28 F Glycol probably has a capacity rating around 25,000 BTU/HR.

One real quick Rule of Thumb Formula for calculating cooling loads is:
Lbs of Product X Temperature Drop = BTU

I hope this is helpful, feel free to contact me if you have any additional questions- I'd be happy to try and help.

Good Luck,

Jim
jimvgjr@prorefrigeration.com

https://www.prochiller.com

Pro Refrigeration Inc.

[eoconnor101]

Thanks for everyone who offered advice.....the last two brews we got down to 50 minutes, then 37. We are running our pump downstream of the plates as advised and also we are running city water against the wort first smaller HX and then we are running the wort against city water that is run through two copper coils with 80 lbs. of ice mixed with 40 degree water from the cold room. It's not pretty but it'll work. We figure we can get close to a half hour if we run the city water in HX1 through a small copper coil in ice as well.

Thanks again, of course eventually a bigger plate HX and a cold liquor tank may be the way to go but we got from mash in to knock out in 5 hours and it seemed like a miracle.

Cheers,
Eric
TSB

[Rick500]

If I were to put together a two-stage heat exchanger (7 bbl batches), I'd run wort again city water in the first stage, then could do one of the following in the second stage:

1. Wort against cold water from CLT
2. Wort against glycol-chilled water from another small heat exchanger (I guess this would technically be more than two stages...)
3. Wort against glycol

What is the preferred method (if there is one) and why?