Can someone give me a run down on how aqua ammonia would occur in an ahydrous ammonia refrig system - Thanks
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Can someone give me a run down on how aqua ammonia would occur in an ahydrous ammonia refrig system - Thanks
JCollins
If air enters system it has moisture in it .
You purge air out but moisture remains .
Over a period moisture builds up especially plants that run in a vacuum .
Other ways it can enter are poor practices with oil or new / secondhand equipment being installed with water in them for whatever reason .
Some accidents also happen if purging ammonia into a bucket of water and it accidently sucks water in ( been there done that and you usually only do it once in your career if your lucky ) .
Can be referred as dead ammonia which can be removed from system , usually low side by distilling samples of ammonia .
Hansen make an automatic one combined with air purger or you make your own as its basically an oil pot with a heater .
Hope this answers your question .
If your system runs in a vacuum you essentially leak into the system. The air can be removed by an older auto-purger but the water remains. Newer purgers can remove water as well.
One of our systems is a 16,000# ammonia system running at 12" of vacuum. It's been running an older autopurger 13 years now and has yet to have a water problem at all despite our old autopurger running about 50 times a day. We test for water content in the LPR every two years.
Some of the pipes and units are from the 60's so we're fairly happy with that performance.
Hi JCollins.
I agree with all the above posts, system in vacuum, old equipment, valve stems etc.,
But sometimes doubt the label stating anhydrous ammonia on bottles. On larger plants when adding several bottles to system, the autopurgers seem to go ballistic afterwards.
In hansen purger litrature it states after adding ammonia system it will probably need purging .
Not sure why as surely they fill bottle after bottle on vacuum , maybe they dont bother sometimes .
to get the gas out is normal with the purgers, and they should run very much after taking in, to get the water out of the system is very hard to do , as it is very soluable, and the only good way is with active coal, a normal drier is not good enough, however ammonia can have lots of water before something happens.
Let’s talk in large system .
Air can be removing very easy from system by air purge system or by vent valves one top of Condenser and Receiver, Normally Air purge is used in two stages or 3 stages system
But about Water?
You know in large system we have oil drain in several place if the designer had a good experience and knowledge and attention about removing water it can be done in system .
Receiver – Separators – Under the collector of NH3 pumps
The best place to remove oil and dirty oil and … is a Receiver (during system operating )
But in Separators and Collector of NH3 pump we have different design for different pressure .
Sometimes we use element to heat oil and … to remove it with valve system
Sometimes we use valve system without heating by elements.
Sometimes just we have oil drain valve.
If you are sure about water in system and you don’t have those system to drain it
(Element to heat oil and … to remove it with valve system) in two stages system,
You have to turn it off until oil and … get soft to drain from Separators (Oil drain valve)
I had experience when I opened NH3 pumps for maintenance I saw water drop and I found
They didn’t drain oil from system and just they have oil drain valve under separator . I put
Small tank under separator and connected to oil drain and another to top of separator tank ( it was valve for gage on top of separator I put T there and used that one) with valve system and element . it worked and we removed all oil and dirty oil and water from system in one month
BUT NOT MOISTURE
the best and easy way to remove moisture put Air purge always in running position and use air vent valves frequency in two or three month
mbc you are NOT complying with regulations.
When you open a vent on top of receiver most of it will be refrigerant and not air.
That is the beuaty of a good air separator it makes the refrigerant so cold it will liquify and not vent.
And NO water will not get out by venting however the ammonia can be cooked out and the rest can be flushed. And yes if any oil in this it will also be flushed. This oil should not be reused as it is full of water. it is hazardous and should be collected as my colleague already told us.
BTW same applies for ***** systems.
I would like to urge every installer to have a purger unit on every 12 installations once a month running one month.
With a good logbook the owners will be happy with the savings they will see on power.
Shooter , each country has its own regulations .
If its Ammonia and not affecting anyone , I would purge to atmoshere .
If I did'nt have a choice and needed plant to run .
Dear Shooter
1 - This is NH3 Not *****
2 – Air vent on top of the receiver goes inside water to solve NH3 and also cover smelling
3 – Time of to use Air purge depends on system operation in what pressure is working and also how often it you have maintains in your system and how often you charge your system.
4 – Main air vent should be done on top of condenser ((highest point in discharge pipe))
Just to add the non condensibles should only be purged from top of condenser when plant is off and water pump + fan run in manual for say 15 minutes . The air migrates to top then purge .
You can purge off top or reciever anytime and condenser liquid drain only
when plant running .
One remark. We can purge the air from the top of the condenser when plant is running. Assume that we have 2 or more condensers. Close discharge inlet valve to one condenser and keep operating water, air on manual. After 15 min. you can purge from the top of this condenser and plant keep running.Quote:
Originally Posted by RANGER1
You can not purge from the top of an ammonia condenser or receiver, well, you can but it's not a very good way to do it.
Ammonia gas is lighter than air.
On a running system the air and gas will be somewhat mixed because of turbulence so venting gas from the top of the receiver or condenser is possible, but you will also release a inconvenient large amount of ammonia at the same time.
On a system that is not running, the air/non condensable gas will remain as a layer between the ammonia liquid and ammonia gas, if you now vent from the top of the condenser or receiver, you have to vent very hard until the air again mixes with the gas that is evaporated from the liquid in the receiver and again you will release an inconvenient amount of ammonia gas.
Most systems that are not fitted with and automatic/ semi automatic air purger should have venting points various places between the condenser and receiver.
If you have an air purger, it will collect small amounts of air mixed with ammonia gas, the ammonia is condensed and drained back to the receiver while the air remains in the purger until it is full of air and unable to condense any more ammonia, now you will either have to purge it yourself, or an automatic one will do it on it's own and continue running these cycles.
The purger is usually connected on the purge points between the condenser and receiver, with a separate line for draining condensed ammonia back to the receiver, or a single larger line that both supplies it with air/gas and drains the condensed ammonia back.
On ***** systems on the other hand, the ***** gas is heavier than air, and so if you stop the system but keep the condenser pumps/fans running, you can purge air from the top of the condenser.
I'd like to clarify my previous post.
I have mentioned about evaporative condensers with liquid seal at the bottom. When we close inlet discharge valve and keep pump and water running, ammonia will start condensing inside of this condenser. Gradually the liquid ammonia will fill up all condenser except air pocket at the top and air can be purged. It is very convenient because the plant can continue to run.