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  1. #1
    Join Date
    Jan 2004
    Posts
    933

    Ammonia for Cold Storage

    Anyone work on ammonia systems? Any body work for cold storage facilities? I do not really understand how cold storage places make a buck. I am comming from the resi side, wondering what life is like on the dark side.
    Still learning opinions welcome.

  2. #2
    Join Date
    Oct 2002
    Location
    Lady Lake, Florida
    Posts
    799
    The only thing I ever did with an amonia system was a cold storage plant in Japan many years ago in the late 70's. We had to baby sit the plant in event of a power outage to perform a shutdown sequence triggered by an alarm. The compressors had a water cooled jacket just like an auto motor. We had to shut and open a series of valves, switches, and disconnects in a certain order. They had gas masks located all thru the bldg at various locations. Basically you sat for 8 hours on second or third shift and prayed you would'nt have to do anything. A few of us volunteered to do it so we could study our books and get comp time off and be exempt from other worse details. It was a cold storage plant that kept -40 degree temps for military commissarys. The japanese civilians worked the plant during the day shift. It was a pretty cool detail.

  3. #3
    Join Date
    Aug 2006
    Location
    Vancouver , Canada
    Posts
    297

    Smile Ammonia systems

    Ammonia is a great refrigerant - 700 btus / pound latent heat of vaporization I believe which is about 10 x R-12 for instance. There cannot be any copper or brass in a system - steel or aluminum are the common metals used ( aluminum for connecting rods on older York direct drive ).

    I have personally serviced and rebuilt numerous ammonia compressors, Vilter, York and Mycom. The applications were skating / curling rinks, bottling plants ( Coca Cola ), food storage, and blast freezing. One has to be aware of the dangers of ammonia, a little goes a long way in the way of alarming you - you get out or don the proper protective gear if there is a leak. Ammonia has a great affinity for moisture, so any cuts, scrapes or sweat on your body burn immediately as the ammonia bonds to the water molecules to for anhydrous ammonia which burns the sesitive skin cells.

    That being said, using proper servicing techniques and donning proper safety gear is paramount; here in Canada, machine rooms are more specialized in the amount of ventilation, alarms, egress etc. I quite enjoyed working on ammonia; though have not for several years. Most systems are flooded chiller brine systems, though TXV systems are common enough. Oil does not move around with refrigerant as well as conventional refrigerants, there is more attention paid to that detail.

    As for the question of how cold storage places make $ ; Low and medium temperature storage is big business - all the food at your grocery store hits a cold storage facility at least once before you get it - I don't know how they charge, but it is like the overflow storage for the food system - the Washington apple you eat today was picked 7 months ago. Other than the initial capital outlay, the biggest cost is warehouse staff and electricity. This is where ammonia comes in - you have to move around 1/10th the number of pounds of refrigerant compared to a CFC system for example - a 125 ton ammonia screw compressor isn't much bigger than a breadbox ( without motor of course ).

    Don't quote me on some of the numbers, but I am close - ah, to long for the days of a burning nose and teary eyes ( you old ammonia techs will know of what I speak ).
    Superheat and subcooling tell it all !

  4. #4
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,463
    sweating balls always got to me.

  5. #5
    Join Date
    Jan 2003
    Location
    San Jose, Ca
    Posts
    2,089
    I grew up around the stuff. Pop worked in an old plant. Origional engine room built in 1912 with used equipment. And they just kept adding on to it over the years. Most of the compressors were cross head machines with flat belts. I loved going to that engine room. I could walk in there and in a feew minutes I knew which machines were running just by the sound.

    Two stage compression on a header system. flooded evaporators with hand expansion valve. By theory the plant was capable of delievering 390,000 tons but during high production times did 490,000 tons. The engine room had to be manned 24/7.

    Building was sold, new owner descided wages were costing too much. Removed all the compressors and installed two bigh 4170 vac compressors fully automated. Power bill went up over $10,000 per month. This was in 1972, power bill increased more than double what the operator wages were.
    Old snipes don't die they just loose their steam

  6. #6
    Join Date
    Nov 2004
    Posts
    25
    gotta love the the ball burner days!!!!!

  7. #7
    Join Date
    Dec 2004
    Location
    Chicago area
    Posts
    1,439
    Quote Originally Posted by 2story View Post
    Anyone work on ammonia systems? Any body work for cold storage facilities? I do not really understand how cold storage places make a buck. I am comming from the resi side, wondering what life is like on the dark side.
    To work on big commercial, you don't necessarilly need to work on ammonia, I've allways wanted to atleast once, but haven't yet, and most likely won't, at least not w/ the Trane company. There are not too many new ammonia systems going in to my knowledge, at least where I am, there are alot of cascade systems aroung here, w/ many various refrigerants. Got one plant at Fermi lab that runs on helium. I don't know the tonage, but it consumes 10% of the electricity here in Illinois.

  8. #8
    Join Date
    Jul 2007
    Location
    Chino, CA
    Posts
    40
    hey freonguy,
    you mentioned that oil doesnt move with "refrigerant" as well as with conventional refrigerants so im assuming that you refer to amonia as refrigerant in your post. would you be able to expand on this a little more? (why oil refrigerant doesn't move well with refrigerant"amonia") and what would happen if you took old amonia coils (25 years old) and used them in a system with R22? would you have more trouble returning the oil back to the compressors? would they even work as far as refrigerating?
    thanks

  9. #9
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,041
    Ahhhh the smell takes me back to my apprenticeship in the UK . First ever refrigeration system I worked on was an ammonia recip system in a brewery.
    Then went to work at a cold storage plant where they had ammonia screws built by a swedish company called Sulzer. I have forgotten all of the tech stuff about it ,only things I really remember are oil return is an issue ,no brass or copper anywhere,venting residue through water kills the smell and we used to leak test using a smoking incense type stick that smoked like crazy when you got close to the leak . That and all the other unpleasant sweaty area stuff .Not pleasant . graham
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  10. #10
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,041
    Im sure some of the more experienced ammonia guys will correct me but I think the oil return issue is to do with the lower refrigerant velocity through the system???? I Think but its along time ago ?? Graham
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  11. #11
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,314
    I'm not an ammonia expert but...the oil return issues with ammonia is because the oil is not miscible with the refrigerant.

    Being heavier than liquid NH3, the oil drops to the bottom of flooded evaporators and low pressure receivers which must be drained of oil.

    Here's a link to an interesting summary of ammonia systems:

    http://www.nhtres.com/differs.php

  12. #12
    Join Date
    Jul 2007
    Location
    Chino, CA
    Posts
    40
    thanks icemaster

  13. #13
    Join Date
    Aug 2006
    Location
    Vancouver , Canada
    Posts
    297

    Oil return

    Thanks for the reply Icemeister - was away from the computer for 3 days.

    Freonguy
    Superheat and subcooling tell it all !

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