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SMP
28-02-2014, 05:12 PM
Hello all,

I'm an apprentice working with two refrigeration operators. As a good opportunity to learn more and contribute to my team I've taken interest in resolving a build up of calcium on our condensors. We have to baltimore condensors, our systems is a 20,000 lb NH3. In our busy season we are freezing 170 tons of fish a day.

On our system it's apparent that the bleed off water line has been closed for some time and as a result or tubes are built up with calcium.

We've contacted a water treatment provider, there hasnt been one, my impression is they are mostly interested in treatment after we get the build up removed.

So, searching the site here I found a thread that briefly mentioned using white vinegar and water 60/40 to break it down.

http://www.refrigeration-engineer.com/forums/showthread.php?33074-Removing-scale-from-evaporative-condensor-by-freezing&highlight=condensor+scale

I've tried a small area and the results look good, but I'm hoping that I can get more information or experiences on doing this... I do not want to damage the galvanizing and since we have to condensors how would you apply this on a large scale?

Thanks in advance!

kiwi
28-02-2014, 10:02 PM
I've used neat vinegar in a purger before to remove scale and it worked well. Never in a condenser though. Typically Id use a product with sulphamic acid like Nalco 5032.

PaulZ
02-03-2014, 11:04 AM
Hi SMP
I have used Citric acid in the past, you used to be able to buy it as a powder and add it to the condenser water and run the pump. You will still have to keep an eye on the galvanizing and don't make the mix too strong.
Paul

passandscore
02-03-2014, 07:59 PM
What's the condenser model number?

I have not found a sure fire way of removing scale from the heat transfer tubing. Most if not all methods require adding a chemical to the condenser water tank and circulating it but because of evaporation you have to constantly check to ensure that the chemical hasn't neutralized which happens quickly resulting in the need to add more chemical. It gets costly. Not only that but the first couple rows of tubing get the most chemical causing the galvanizing to be removed from those rows.

I'm interested to hear alternative solutions to this problem.

SMP
03-03-2014, 04:52 PM
Thank you for your replies,

I sapose it's a personal preference to use a more passive, less toxic method to remove the scale. We also have several months down time in our fishery that allows for slower options.

Yea we are evaporating a lot of water when freezing product, and without our bleed off working its probably a text book example... when I figure the site out I can post some pictures ... scale isn't bridging between tubes just building up.

Model #s I got off condensor are vc2-711r and vc1-48 om

Thanks again,

Magoo
04-03-2014, 01:27 AM
managing the PH levels is what it is all about, the vinegar is alkaline and citrus is acidic, and getting the calcium into solution as total dissolved solids ( TDS ) for flushing. Pre treatment of fill water with a water softener also helps, removes/ reduces the calcium content in water can reduce the amount of chemical treatment required. Spirax Sarco offer a good automatic dosing system if available in your area.

kiwi
04-03-2014, 06:10 AM
Vinegar is acidic. Acetic acid IIRC but thats just semantics as the post is accurate.
A good shock dose of an acidic solution that will passivate followed by a neutralising solution is the best way to move stubborn build up. Common blackboard chalk will be a good indication your solution while shock dosing remains low enough in pH to dissolve scale build up.
The best solution though is to not get in the position to have to combat scale build up as per Magoo's post.

SMP
05-03-2014, 04:40 PM
Your replies are very helpful! I did a lot if reading before posting and your information is assuring me that I was getting the idea. Aside from the physical process, it's pretty simple chemistry.

The mention of chalk, very clever! With the chalk and monitoring ph I can make sure its working while keeping it in the safest ph range. Can't wait to see that calcium going down the drain. :-)

Now to see what the chief thinks.

Magoo
06-03-2014, 01:17 AM
Hi Kiwi.
you are correct vinegar is acetic acid CH300H + water content. Must try that for a de-scalar.

kiwi
06-03-2014, 09:32 AM
Hi Kiwi.
you are correct vinegar is acetic acid CH300H + water content. Must try that for a de-scalar.
One of our clients uses it in bulk so we can get 20l containers of surplus vinegar to flush out scale from their air purger bubbler and drain. Works a treat.

SMP
18-03-2014, 04:38 PM
So, I got into the mixing stage on a small scale after reading a few more articles.


General.

The corrosion rate of zinc under immersed conditions can be high in acidic solutions below pH 6 and alkaline solutions above pH 12.5. Between these limits the rate of corrosion is much lower.

http://www.galvanizeit.org/hot-dip-galvanizing/how-long-does-hdg-last/in-water

When calculating my solution of vinegar and water 60/40 I get 4.133, flip vinegar and water 40/60 I get 5.098.

To keep in the safest ph range mentioned in the article I would want vinegar to water 20/80 producing ph of 6.064? These are mathematicly produced #s of ph.

An earlier poster mentioned that ph is the value of interest, does this apply to this process? The higher concentration would be a shock treatment correct? The lower concentration would be slower, easier on the galvanizing but would it be to weak to break down the calcium?

Thanks in advance!

SMP
01-08-2014, 11:47 AM
Man life comes at you fast sometimes!

Following up on this thread,

I did spray the coils in a few spots inside with a 60/40 mix, and rinsed 60 minutes later. I was surprised to see it breaking the build up down! Wasnt 100% cleared of coarse but definetly removing it, I sprayed 3 times and there was a notable difference. We added 40 gallons to our larger condensor and ran it for awhile and even that small amount seemed to be making a differnce.

Our company was bought and we had to redisign and rebuild our processing area so no further work was done with the condensor and vinigar however...

The new company approved an automatic system using Potassium Hydroxide injected into makeup water. Further More...

Turns out our auto-purger was not purging correctly, we rebuild it replacing sensors and droped our head pressure 30lbs. Believe it or not theres no temperature sensors on our high side, Im sure that has cost them in the long run... to think a couple hundred bucks wasnt spent that would have saved thousands over the years!

So yes I will be expressing to them the importance of adding some!

Thanks again for your replies and I apolagize for taking so long to reply!

Josip
01-08-2014, 03:45 PM
Hi, SMP :)

welcome to RE forums ...


Hello all,

I'm an apprentice working with two refrigeration operators. As a good opportunity to learn more and contribute to my team I've taken interest in resolving a build up of calcium on our condensors. We have to baltimore condensors, our systems is a 20,000 lb NH3. In our busy season we are freezing 170 tons of fish a day.

On our system it's apparent that the bleed off water line has been closed for some time and as a result or tubes are built up with calcium.

We've contacted a water treatment provider, there hasnt been one, my impression is they are mostly interested in treatment after we get the build up removed.

So, searching the site here I found a thread that briefly mentioned using white vinegar and water 60/40 to break it down.

http://www.refrigeration-engineer.com/forums/showthread.php?33074-Removing-scale-from-evaporative-condensor-by-freezing&highlight=condensor+scale

I've tried a small area and the results look good, but I'm hoping that I can get more information or experiences on doing this... I do not want to damage the galvanizing and since we have to condensors how would you apply this on a large scale?

Thanks in advance!

bleed off water line must be open all the time ... but the best is to find all relevant info about water treatment for your condensers here ...

http://www.baltimoreaircoil.eu/rld

http://www.baltimoreaircoil.eu/downloads

cannot find your type of condensers ... seems some letters are missing ....

hope this will be of some help to you ...


Best regards, Josip :)