I wanted to write about brewery heat exchanger maintenance, because the importance of upkeeping this critical piece of brewing equipment, is often overlooked.
For example, the brewery in Shanghai I took operational control of last year, was in a bad way. I shudder when I recall how bad the conditions were.
The picture below shows how one of the carbonation stones at the brewery looked. Let’s just say the heat exchanger wasn’t in great shape either.
The brewery didn’t have a proper maintenance plan to keep the heat exchanger in good condition. To save time, I’ll refer to a common abbreviation used in the brewing industry, when discussing heat exchangers, which is to shorten to HX.
A HX can be a point of infection, if not looked after properly. The role of a HX is to flash cool wort on the way to the brewery cellar. As the wort loses heat it becomes susceptible to infection.
With the correct brewery heat exchanger maintenance and upkeep, a brewery shouldn’t have any issues. So, today I wanted to share the process I use, which has been refined over my career.
Brewery Heat Exchanger Maintenance – Where to Begin
This is a guide for people newer to the industry plus, similar advice I offer to my clients when asked.
Some brewers, may have different strategies to the ones I’ll write here, but for the most part what I will describe is industry standard.
Let’s start with taking a heat exchanger apart. It was one of the first task I did, when starting at the current brewery I’m at.
Actions To Take Before Opening a Heat Exchanger
End Plate Measurement
Prior to opening a heat exchanger, you should measure the gap between the end plates. This will be your guide for how much to tighten, when putting the HX back together.
You don’t go by how tight you do the nuts and bolts, the torque. Some heat exchanger manuals, tell you what the space between the two end plates should be.
Spare Gasket Set
It’s prudent to have a complete set of spare gaskets before opening up the HX. During use gaskets can get stuck and when dissembling the HX they may break up.
A spare set of heat exchanger gaskets are always handy to have in reserve at a brewery.
Heat Exchanger Plate Placement – Mark with a Big X
The plates of the HX maybe numbered, which will make putting it back together easier. The plates need to be put back in exactly the same order, as they were before disassembly.
With some heat exchangers this is easier, as they come with long carry bars. So, the plates can be slid across, but still kept in order. Like the picture below.
By sliding the plate across one-by-one; there should be enough gap to clean them by hand. If you don’t have a HX like the one above, then you can mark the plates with a big X.
If the heat exchanger doesn’t have a long carry bar to keep the plates in order. Makes sure you can put the plates in order by referring to the marked numbers or X.
Brewery Heat Exchanger Maintenance – Cleaning When Disassembled
Once the HX exchanger is dissembled, visually inspect each plate and clean it by hand. It’s often surprising how much matter makes it into the HX, even with a hop strainer inline.
I use gloves, sponge, warm water and rinse down with a hose after scrubbing. Don’t use a anything to abrasive for scrubbing the plates, as I don’t want to scratch them.
Sometimes there can be sharp edges when handling the plates. So, the gloves protect your hands from potential cuts too.
It’s a fairly simple exercise, but take your time. Hop matter and other materials can become tightly compacted and be hard to remove.
Once you’re happy all the plates are thoroughly cleaned it’s time to put the HX back together.
Re-Assembling the Heat Exchanger – Brewery Heat Exchanger Maintenance
Push all the plates to one side (and the end plate), the side closest to the brewhouse usually. Then you can begin to tighten the bolts.
You need to tighten up the bolts evenly. So, get them (usually there are 6 or 8) snug, but still fairly loose.
Then bring each one in around 5mm (0.2 of an inch), then move onto the next one. Slowly tightening the HX back together.
Continue doing this till the distance between the end plates is the same as measured at the start. You may find it needs to be tightened a little bit more still, if you notice leaks/weeps
However, if needed, do so gradually. Once the HX is reassembled, I like to do a hot liquor backflush rinse.
It’s not 100% necessary, but a 2-to-3-minute rinse with 80°C+ water is good practice. Plus, allows me to check for weeps/leaks. Water is less viscous than wort so, if water doesn’t leak you should be fine.
Hopefully any matter missed, will then be flushed out rather than getting stuck in the heat exchanger once more. When backflushing, run the flow at around 150% of normal flow rates.
Brewery Heat Exchanger Maintenance – Regular CIP After a Brew Day
Every brewer will have their own method. Also, after brewing big beers, heavy in adjuncts you might want to extend the chemical cleaning cycle.
Like when hot rinsing, you’ll want to reverse the direction of flow when cleaning. So, everything listed below is done in the reverse direction:
- Pre-rinse with cold water – around 1-minute
- Fast flush with 80C water – To pre-heat the system, say for 2 to 3 minutes
- Caustic at 85°C (185°F) CIP cycle for 30 minutes (can be longer if needed)
- Rinse with hot water – 2 minutes
- Rinse with cold water – ensuring the caustic has been thoroughly rinsed out.
I understand not everyone is able to run this process in reverse. Happens if a system layout and design make it too troublesome.
You should at least do an extended cold-water pre-rinse backflush, to remove hop and other matter first, before the caustic cycle.
Plus, another water backflush rinse after the caustic cycle too. Again, to make sure any hop matter doesn’t become compacted in the newly cleaned HX.
Further Notes for a HX CIP
Some brewers like to leave caustic packed in the heat exchanger between brews. There will be other brewers who don’t.
Furthermore, some brewers like to leave sanitation-strength PAA (peracetic acid) solution packed in the HX between brews.
This shouldn’t affect HX gaskets (usually EPDM), as they should be rated higher than the threshold for compatibility when using PAA. Please check with your equipment supplier though to be sure.
It’s known PAA can degrade quickly, it’s why PAA used in brewing typically contains H202, as it can drastically improve effective capacity for longer period of time.
However, if leaving the HX packed with PAA, you should still run a fresh sani-loop of the HX, if it’s been left for more than a couple of days.
Please note: Some companies like Muller and Thermaline recommend against packing with CIP fluids, from a health of the equipment standpoint. The choice is up to the individual brewer.
What’s the Right Way?
I leave the heat exchanger as is, after the cold-water rinse. The day before the next planned brew, I do a long hot water rinse (85C). Then run sani (PAA) the day of the brew. For sani-prep of a HX please see below.
Brewery Heat Exchanger Maintenance – Preparing HX for Wort Collection my che
When sanitizing ready for collecting wort to the fermentation vessel (FV), there are two main methods people use. One is with hot water and the other with chemical sanitizer.
Many brewers prefer hot water, as heat penetrates, while chemicals are subject to turbulent flow so, may not contact every surface.
Using Hot Water / Fire-Loop
The ideal setup is to flush the heat exchanger and all beer hose to the FV with hot water (preferably at 85°C+).
Put a T-piece on the inlet to the FV so, can recirculate the hot water back to the hot liquor tank (HLT). As you don’t waste too much hot water.
Ideally, you’d do this hot “flush” (also known as a fire-loop) at the last available moment before the line is needed for wort. Running the loop for 20 minutes.
Other brewers will run a certain volume of hot water through the HX and beer hose (say 350-liters). How much water is run through the heat exchanger, depends on the system size. A loop is better as it wastes less water.
With my setup, I use sanitizer, I put the needed amount of PAA diluted to the concentration recommended by my chemical supplier, into the brew kettle.
Then I run the PAA though the heat exchanger, all the hard-piping and beer hose to the FV. I actually use the same PAA, to sterilize the FV I’m brewing into.
So, I connect the beer hose to the fermentation vessel CIP arms, let some liquid drain out from the bottom outlet till I have PAA, then close the bottom valve. Meaning I collect the rest of the PAA into the FV, for CIP.
It means all my lines are sterilized ready for wort collection. I then do a PAA CIP later on, to sterilize the FV.
The beer hose which I’ll use for connecting to the bottom of the FV/Wort collection is closed off with a butterfly valve, full of PAA ready for when needed.
I connect a T-Piece to the FV bottom inlet. It means I can drain the water till I get PAA in the FV. Furthermore, I like to do a quick hot rinse (2-miutes) of the lines from the heat exchanger to the bottom of the FV through the T-Piece to the drain before running wort.
It’s not necessarily needed, but it’s an extra step I like to add. Ensure there’s no PAA in the lines and a final hot rinse adds some extra security.
Anyway, when using sanitizer, it can be done early on during the brew day, then left packed until ready for wort collection.
And that’s about it! Collect the wort to the FV, and then carry out the cleaning cycle.
Brewery Heat Exchanger Maintenance – Some Final Notes
Once final price of advice when discussing brewery heat exchanger maintenance, is the need to perform an acid cleaning cycle.
When to carry out a acid cleaning cycle on the heat exchanger, depends on the brewery and brew schedule. Some breweries will do an acid clean every 10 brews. Whilst others will carry out an acid clean quarterly.
An acid CIP removes beer stone and inorganic mineral build-up. Helping keep the heat exchanger in good shape plus, run as efficiently as possible. Usually the acid is a phosphoric/nitric mix, the concentration used depending on the recommendations of your chemical supplier.
Small Extra Actions Worth Noting
There’s some additional maintenance we suggest:
- Keep the carrying and guiding bar clean with paraffin oil.
- Make sure the tightening bolts are cleaned for easy opening, closing and adjusting.
- Lubricate threads of tightening bolts with an EP (extreme pressure) grease.
- Grease the suspension wheels on the pressure and connection plates.
Brewery Heat Exchanger Maintenance – Conclusions
When it comes to running a successful brewery, preventative maintenance is key. Look after a heat exchanger and it’ll serve a brewery well. Always clean straight after use, when possible, as it’ll make cleaning easier…wort is very sticky and can dry hard.
Keep a whole set of gaskets spare just in case and remember to do a regular acid clean to keep a HX in tip-top shape. And there we have it, brewery heat exchanger maintenance.
Thanks for reading; I hope there was some actionable content there for you. If you’ve any follow-up questions please feel free to contact me. My email address is:
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Thanks for reading and have a great day!