Crashing Fermenters?

[Buster]

What is the proper amount of time it should take to crash a tank? I just installed a new 240 bbl fermenter and I am having a hard time bringing it down to desired temp within 24 hours(10 deg/day). Glycol Temp is not an issue, but flow seems to be the culprit. Not ever having owned a fermenter this big, I am wondering if the bigger tanks take longer to cool than smaller tanks?

[william.heinric]

Placement of the probe

I have noticed with our 50 and 100 bbl tanks that the probe is placed in the warmest spot in the tank, ie just above the cone. The heat that accumulates here is of course from the density of the liquid and the accumulation of the yeast. There are a couple of tanks that we have that read high all of the time, but when we get down to the last 20%, the beer is normally -2 to -3C.

My solution to the problem was to choke back the top jacket and middle jacket so that a larger proportion of the glycol passing through goes through the hotspots.

Out of curiosity, are there big bubbles in your glycol line? That could cause an airlock, or at least decrease the efficacy of your jackets.

Just a thought.

Bill

[Ted Briggs]

second on air- if you just installed them make sure all the air is out of the cooling lines.

[Alex T]

Hey,

One issue I've had in the past with similar sized tanks (200HL) is having the glycol flowrate too high - suspected icing on the insides of the jackets which was decreasing the heat transfer. So sometimes less is more..... just another place to look.

Cheers,

Alex

[liammckenna]

cooling speed in a tank is largely dependent on the ratio of surface area (of cooling jackets) to volume of product. It may also be augmented by flow rate (and making sure lines/jackets are purged of air).

In larger tanks, this ratio is usually smaller and consequently cooling takes longer.

Also, logic dictates that for the same reason, the rate of ambient heat pickup by a cold tank (in either insulated or non-insulated vessels) is less in large tanks.

Pax.

Liam

[ParishBrewingCo]

cooling speed in a tank is largely dependent on the ratio of surface area (of cooling jackets) to volume of product. It may also be augmented by flow rate (and making sure lines/jackets are purged of air).

In larger tanks, this ratio is usually smaller and consequently cooling takes longer.

Also, logic dictates that for the same reason, the rate of ambient heat pickup by a cold tank (in either insulated or non-insulated vessels) is less in large tanks.

Pax.

Liam

I second Liam. The ratio of liquid volume to cooling surface area gets bigger with bigger tanks. This is similar to the principle of using larger barrels when aging beer for less wood character as well as less oxidation. One would imagine it should take quite a while longer to chill than a tank half that size.

One thing to check is the glycol compressor. If it is running all of the time while you're crashing this tank (or far more often), you may be at the capacity of your system and the glycol may be increasing in temp more than on a smaller tank (thus slower heat x-fer since driven by delta T).

Andrew

[Buster]

Thanks for all the suggestions. I am still dealing with the same issue of trying to get the flowrate increased through the jackets. Glycol temp is fine, but we did some flowrate tests on the system and here are the results:

Before we go in to the tank: 10 sec to fill a five gallon bucket.
After we come out of one jackets: 1:25 seconds to fill a five gallon bucket
Putting a 1 hp booster pump in front of "Glycol In" port and testing after the jacket: 50 seconds

I checked pressure before we go into the tank and before the pump and I was getting 20 psi before it branches to that tank. The tanks jackets are rated at 90 psi, which seems a little crazy to me. All of my other tanks are rated to 20 psi.

I thought for sure that we would be able to knock the temp down with the booster pump, but it is still sitting aroung 34-35 deg and it won't seem to make it any further.

More importantly, why is it requiring so much pressure/flow to get through this jacket? I haven't experienced this with any of the other 30 tanks we have.
Given that it is a new tank, not from any other manufacturers that I have used before, I am concerned about having to much restriction on these jackets, and requiring more pressure than I have easily available.

[Guestimate]

Buster,

Has your glycol issue been resolved? If not, do you know the design of the cooling jacket itself? Sounds like you have a dimple jacket in which the manufacturer spots welds a piece of sheet metal on to the body and then inflates the jacket with compressed air to create space for flow. If this is the case, they have not manufactured the cooling jacket correctly. My guess is they used too heavy of a gauge of sheet metal (hence the 90 psi rating) and the jacket did not properly inflate. You can PM me if you do not feel comfortable posting, but I would love to know who the manufacturer of this tank is.

Kevin

[gitchegumee]

Dimple jackets are always formed first and then welded on. Never are they welded and then "inflated". Some other manufacturing processes use "hydroforming" with hydraulic pressure, but this isn't one of them. Might look like it, but no. There are machines that automatically weld the dimple jacket to tanks--for larger manufacturers. Otherwise, it's a very long & tedious process.