HX breakdown frequency?

[TGTimm]

How often do you all break down the pack on your wort HX? We've been doing it when CIP starts to fail (efficiency drops)--about every five or six years, and the boss wants to do it more often.

[brewmaster 2011]

In 10 years for brewing at 4 different brewerys, I have yet to break down a HX. i have never seen a change in knockout temp due to build up. I clean my HX with KOH and follow it with birko acid brite #2. I also clean it as part of my loop when I cip my fermenters. How are you cleaning your HX?

[mmussen]

When I first started running a brewery it was all used equipment so the HX had to be fully pulled apart and thoroughly cleaned. How dirty the inside was actually surprised me so after a year I opened it up again to find everything still looking very nice and clean. Since then I've been adding a year to it every time to see how often it actually needs it. 2 was not an issue. I haven't opened it up after 3 years yet...

[dick murton]

Don't do it unless your flows are dropping, or chilling parameters no longer being achieved, or you have infection. Every time you open up and close the plate pack you are liable to have to tighten up further, reducing the gap, so increasing the risk of blockage, and increasing the risk of seal damage, or poor resealing, so making liable to leakage.

Good chemicals, high flow rates, back washing and regular cleaning make opening up rarely necessary.

[wailingguitar]

Don't do it unless your flows are dropping, or chilling parameters no longer being achieved, or you have infection. Every time you open up and close the plate pack you are liable to have to tighten up further, reducing the gap, so increasing the risk of blockage, and increasing the risk of seal damage, or poor resealing, so making liable to leakage.

Good chemicals, high flow rates, back washing and regular cleaning make opening up rarely necessary.

This ^^^ I have done it once in 26 years and we regretted it afterwards... the plates looked great when we opened it, and then we had seals blow out the first time we put pressure on it and had to tear the thing apart again to fix it. Total waste of time that was!

[TGTimm]

Hmm... this pretty much echos my feelings. We've broken the HX down twice in the ten years we've been using it--once when we first got it (used), once because the boss thought we needed to replace the gaskets. I've been the one that does the break down/reassembly, and it gives me the willies just thinking about it--while I have a manual with diagrams showing how the plates go, I can't make heads nor tails or the schematics.

We are experiencing a loss of efficiency--KO times have doubled. We think the problem may be calcite scale on the water side (our water has extremely high carbonate hardness). Acid washing the water side didn't help. Otherwise, our CIP procedure is pretty much the same as you all describe.

I'll be following the advice of someone here on another thread and painting diagonal lines on the plates to make it easier to keep them in the correct order, but still....

I ordered a set of gaskets ($675) just in case....

[dick murton]

If you used phosphoric acid, you will have converted the calcium carbonate to calcium phosphate, which is even less soluble, and may well be forming an even less removable layer. You need to use nitric acid. I know lots of people say you can descale using phosphoric / nitric mix, but my experience is that this is nowhere near as efficient as pure nitric based acid detergents. You could try a high EDTA content detergent, but I am not sure how effective this will be on phosphates, though it should be better than acid if you now have calcium phosphate.

[TGTimm]

Strangely, Dick, I've been using Phos Acid to remove calcite scale for years now, where I need a no-rinse or minimal rinse solution. I've never seen any insoluble deposits after such cleaning (excluding large chunks of scale broken loose by the acid wash, which eventually dissolve completely), nor any precipitate in my cleaning buckets. In fact, I just cleaned a strainer basket from our HL system this AM--which was fossilized--and I just looked at the tub I cleaned it in--nothing.

The insoluble deposits I'm familiar with are apparently silicates, which a wash with caustic usually loosens or removes.

I broke the HX down this morning, and was surprised to find... nothing. A few hulls on the wort side, a little iron contamination on the water side (but no scale), but nothing to account for the rather abrupt loss of efficiency. Back to the drawing board....

I'm now at a loss as to what is wrong. Our KO times have nearly doubled, and our recovered cooling water temps have dropped--any ideas, anyone?

[mathman]

Mine will do the same thing when my cooling water is too warm. I cool from a CLT, but filling it with 80+ degree Florida ground water, sometimes its off when its time for next batch. When I decrease the wort flow to hit KO temp, it decreases the contact time with the cooling water hence cooler recovery temp.
Another time I had the ball valve go bad that I control flow with. It increased my Clt flow rate which also screwed up contact time.
Just trying to throw some ideas out there.

Fran

[TGTimm]

Hmm... we've had some very warm weather lately (but who hasn't?). Unfortunately, we did not monitor our domestic water temp, but it may have gone somewhat above our normal 50F. I had thought this would increase the output water temp, but your point makes sense--slow down the wort while keeping the water flow the same=lower output water temp. I'll look into it.

As for valve problems, we use a VFD to control pump speed on the wort side, while the water side pretty much stays at full throttle--on a 2" line.

Thanks for the ideas--

[mathman]

Since this thread talks about HX rebuild, what gasket material is recommended? NBR, EPDM....?

Thanks,
Fran

[TGTimm]

Contact your HX manufacturer. They'll ask about the chemicals and temperatures of your particular usage, and sell you the ones you need ($$$).

FWIW, the ones I just bought for our Mueller Accutherm are EDPM, with a few Teflon and other bit tossed in--these gasket kits are complicated. Full kit, including glue, for an AT20 with 27 plates and single reverser: $675. Our old gaskets were fine, so this kit goes in the "Critical Spares" trailer.

[lhall]

Timm,

I can't remember the formula exactly, it's been twenty-two years since engineering school - but the three things that matter at flow rate, delta-T, and heat exchange coefficient. I think it is:

Qw(DTw)(HEw) = (Qh2o)(DTh2o)(HWh2o) where w= wort side and h2o = water side

For a given heat exchange efficiency, the things that matter are the delta T of the water, and the flow rate of the wort (for us). Those are the two things we can control easily. Get the water cold enough, and you can run the knock-out pump faster.

For us, our city water temperature goes up to over 80 F in the summer. It takes half our cooling capacity just to get it down to 50 F for the next knockout. Remember, on a counterflow heat exchanger, the wort exit temperature will never get much closer than +5 F over the incoming water temperature. A 10 F swing can have a big effect.

[TGTimm]

...and a ten-degree rise in the city water temp seems to be what we have. Our "normal" water temp is around 45-47F; I measured it yesterday at 57F. If this becomes a summer trend, we'll have to look at adding another HX with glycol chilling.

Funny how the warmest summer--especially June and July--can affect things.

Good thing winter is coming....

[lhall]

Timm,

Man, I wish we had 47 F water! It doesn't even get that cold in the dead of winter. Half our cooling load in the summer is just trying to get city water down from 80 F to ~40 F.

This year, I added a pre-chiller glycol heat exchanger on the city water going into to fill our cold liquor tank. That seemed to help get the cold liquor tank down to 40 F faster than just relying on the gold liquor glycol alone. We got through the summer this year without as many issues with our glycol temperature rising.