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Thread: Flooded Ammonia Part Two
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09-03-2006, 01:58 AM #1
Flooded Ammonia Part Two
The screw compressors are: Howden, Sullair, Mycom, and Dunham-Bush. Most of these are at least 20 years old, and all run very well.
The one thing I do not like about the pumper drums is that you have to maintain a minimum gas pressure for pumping the liquid. Otherwise they are very simple to understand. You are exactly right about the NRV's.
This thread is getting very long. Perhaps we should start a new one??
Yes, almost forget nothing about controls and valves: old one Phillips Refrigeration, Johnson Controls, Danfoss or other..
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09-03-2006, 07:39 PM #2
Re: Flooded Ammonia Part Two
Sullair started off by manufacturing twin screw compressors for compressed air systems. Sometime in the 1960's or 70's they started to package compressors for refrigeration applications; ammonia, *****, and helium among others.
I installed several of these and really like them. Very simple, easy to work on...
Sometime in the late 1980's they were involved in a very large heat pump system for an office building. R-22 liquid overfeed, ice banks for thermal storage, evaporative condensers, etc. An industrial refrigeration system being used for office air conditioning.
Someone miscalculated the building envelope loads and the whole thing became a legal mess. Everyone had to pay some money. Shortly after that Sullair did not sell compressors for refrigeration service anymore.
I don't know what the whole story was, but the legal problems left a bad feeling for everyone involved in the project from what I heard.
The good thing about pumper drums is that you can change the transfer rate. A little more or a little less. It is hard to do that with a mechanically pumped system.
I really prefer the mechanically pumped systems though. If you have the liquid feed valves setup properly, you can really reduce the discharge pressure on the compressors.
If you reduce the discharge pressure on the pumper drums too much, the transfer rates begin to slow down so you could run out of liquid to the evaporators.
If we can find enough to discuss, can we make it to "Flooded Ammonia, Part III?
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09-03-2006, 08:07 PM #3
Re: Flooded Ammonia Part Two
Josip,
Here is a picture of a Sullair screw compressor package.
From one of my old catalogs...
They were painted about the same color of green we have on the RE forum pages.
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09-03-2006, 10:15 PM #4
Re: Flooded Ammonia Part Two
Originally Posted by US Iceman
The good thing about pumper drums is that you can change the transfer rate. A little more or a little less.
It is hard to do that with a mechanically pumped system.
I really prefer the mechanically pumped systems though. If you have the liquid feed valves setup properly, you can really reduce the discharge pressure on the compressors.
If you reduce the discharge pressure on the pumper drums too much, the transfer rates begin to slow down so you could run out of liquid to the evaporators.
Using pumps is ok and very simple, having problem with pressure when you have a small cooling demand 2-3 roms out of 10-12.
For that reason they install double ammonia charging lines to evaporators, one from pumper drum and another one from economiser coil. This coil is smaller becuse it is working during recharging of pumper drum.
If we can find enough to discuss, can we make it to "Flooded Ammonia, Part III?
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09-03-2006, 10:31 PM #5
Re: Flooded Ammonia Part Two
Originally Posted by US Iceman
Today all of them are very high maybe for easier maintenance . You must have scaffolds around to do service.
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10-03-2006, 03:51 AM #6
Re: Flooded Ammonia Part Two
Originally Posted by Josip
This is what I have seen.
On one system we ran the discharge pressure down very low in the winter to see what would happen. Everything worked OK except for the pumper drums (these were for transfer, not liquid overfeed). The accumulator started to fill up because the transfer rate was not fast enough. The system shut down on high liquid level.
I would expect a similar thing to happen on the liquid make-up valves (intercoolers, etc.). The lower pressure differential changes the valve capacity, so once again we need larger valve ports.
The trick is to find a way to use multiple valves, or a valve that have sufficient capacity at both conditions (minimum and design differential).
Using pumps is OK and very simple, having problem with pressure when you have a small cooling demand 2-3 rooms out of 10-12.
For that reason they install double ammonia charging lines to evaporators, one from pumper drum and another one from economiser coil. This coil is smaller because it is working during recharging of pumper drum.
Can you provide a quick piping sketch of the system you describe please?
Like Star Wars or The Lord of the Rings/
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10-03-2006, 03:58 AM #7
Re: Flooded Ammonia Part Two
Originally Posted by Josip
Some of the very large screws are still mounted down low. The separator shells cannot accommodate the very high weights and motor torque.
Personally I like the lower models because they are much easier to work on. You do not have to be a monkey to work on anything.
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10-03-2006, 11:21 AM #8
Re: Flooded Ammonia Part Two
If your systems use the 3-way valve I think we can use a larger valve port. The larger valve port will allow more gas volume at the lower pressure differential.
This is what I have seen.
This design is not comon here and I want to learn something more...
On one system we ran the discharge pressure down very low in the winter to see what would happen. Everything worked OK except for the pumper drums (these were for transfer, not liquid overfeed). The accumulator started to fill up because the transfer rate was not fast enough. The system shut down on high liquid level.
What sort of problems do you have when only 2-3 rooms are cooling? Is it the pump discharge pressure or pump suction pressure?
This sounds like you have only one pumper drum to feed the system. Most the systems I have seen will use two pumper drums. One fills, while the other is transferring liquid to the evaporators. After one has emptied, the other drum is ready to go. They cycle back and forth to maintain liquid supply.
Can you provide a quick piping sketch of the system you describe please?
Maybe I can make couple of scans and put them together to make it complete.
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10-03-2006, 02:28 PM #9
Re: Flooded Ammonia Part Two
Originally Posted by Josip
What about HG defrost if any, when you have very low condensing pressure?
Since the defrosting pressure is set for the equivalent temperature of 10C, this establishes the minimum hot gas pressure you need. Now you have to add the pipe pressure losses to the defrost pressure setting of the valve.
This total pressure is then the minimum pressure you need for the discharge pressure.
I have worked on some systems where we were able to run the condensing temperature down to about 15C and still defrost the coils in under 30 minutes.
Can you, please, briefly explain idea to use pumper drums for liquid transfer to receiver. Is seems to me very complicated with so many level controls, valves...
If the transfer drum pushes the liquid into a receiver controlled at a pressure lower than discharge pressure, you need sufficient differential to move the liquid.
In other cases, a positive displacement pump is used to transfer the liquid. The Phillips compressor protection method is one way.
As you say these are very complicated with all of the valves, small piping, controls, etc. I do not like these systems for those reasons. I prefer to keep things simple.
Coming down to 2-3 rooms and running compressor even at minimum capacity you can come under set point causing pump stop due to low pressure difference...
In this case you need more capacity reduction in the system, but then you have already explained the problem.
industrial plants where client ask to install minimum units...Last edited by US Iceman; 10-03-2006 at 02:30 PM. Reason: correcting quote
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10-03-2006, 06:06 PM #10
Re: Flooded Ammonia Part Two
Originally Posted by Josip
I hope this explains how the system is being used.
Best Regards,
US Iceman
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10-03-2006, 07:56 PM #11
Re: Flooded Ammonia Part Two
hello everyone, put this link once before ,http://www.wea-site.com/papers.html makes for some good reading, well simplified. US Iceman ever work with any of the los angeles industrial people? my past company had a long relationship with mr Kohlenberger, just curious, best regards
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10-03-2006, 08:14 PM #12
Re: Flooded Ammonia Part Two
Hello, US Iceman
See attachments: freeeee
acad zip and pdf, you can choose
First start manually it was not nice. Not having a readable blue print drawing decide to make one in autocad. take some time but .....
Some valves and lines missing but have no nervs to finish, hope it will be ok if not....ask
Stan1488 your link seems pretty good, need some time to read it, thanks
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10-03-2006, 08:17 PM #13
Re: Flooded Ammonia Part Two
Hello
just entered RE i just love ammonia iam form-Denmark home of Gram Danfoss and Sabroe, i have workede for Sabroe and Yorkref, i can see that you are a fan of sabroe Stan1488,
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10-03-2006, 08:22 PM #14
Re: Flooded Ammonia Part Two
Welcome Casper,
nice to have some more guys loving that stinking but natural fluid
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10-03-2006, 08:30 PM #15
Re: Flooded Ammonia Part Two
hey josip
I just lookede at the system
what is?
The temp of the eco?
the temp of the rooms?
the pressof the eco?
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10-03-2006, 08:48 PM #16
Re: Flooded Ammonia Part Two
Hi guys,
Welcome to the RE forum kasperDK. It is very nice to have other ammonia people to talk to.
I'll try to answer some of the questions...
Originally Posted by stan1488
Thank you for re-posting the web site link. I will review that also.
Originally Posted by Josip
Originally Posted by Josip
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10-03-2006, 09:03 PM #17
Re: Flooded Ammonia Part Two
Hi Josip,
Looked at your drawing.
It looks like the high pressure gas for pumping liquid comes from the receiver. When the pumper drum is filling, the liquid from the economizer is flowing to the evaporators.
After the pumper drum is full, the high pressure gas from the receiver pushes the liquid out of the drum and into the liquid line.
One thing I have a question about is the liquid from the economiser. It is at discharge pressure. When the pumper drum transfers liquid into the liquid line is there a NRV in the liquid line from the economiser (before the liquid line from the pumper drum)?
If the gas pressure to the pumper drum is lower than the liquid line pressure from the economiser, the liquid would not flow out of the pumper drum. Unless there is some elevation difference for gravity.
Or, are there other control valves which help this?
Perhaps I am missing something???
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10-03-2006, 09:15 PM #18
Re: Flooded Ammonia Part Two
i have the same idea but i think ther are a ON/OFF valve in the liquid line form the economiser ther are controled for the Pumper drum level indikator
How dos this system react wenn you use HG defrost?
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10-03-2006, 09:19 PM #19
Re: Flooded Ammonia Part Two
Ther are a ON/off valve underthe suction return line to the seperator this must be controled form the level indikator in the Pumper drum
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10-03-2006, 09:22 PM #20
Re: Flooded Ammonia Part Two
Originally Posted by kasperDK
The pressure in the liquid line would decrease due to the lower evaporating pressure. When the liquid line pressure is low enough, the liquid would then flow from the pumper drum.
How dos this system react when you use HG defrost?
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10-03-2006, 09:27 PM #21
Re: Flooded Ammonia Part Two
Now I see the valve. That completes the picture and answers the question.
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10-03-2006, 11:13 PM #22
Re: Flooded Ammonia Part Two
Sorry guys,
forget to put the marks on solenoids and NRV's
On the liqid line before pumper drum is a flap type NRV (reason is; liquid by gravity force can open it to fill up pumper drum) after PD is normal check valve because we are using HP gas to push the liquid by opening left valve group on the top of PD. When we get the signal that PD is empty valve groups on the top of PD cycle (left OFF/right ON) to close the HP gas to equalize pressures in PD and surge drum and start gravity filling.
Simultaneously with right valve group over PD we have ON signal to solenoid valve on liqiud line from economiser to evaporators. This liquid is some kind of make up (notice there is not other line for that) for complete system and liquid delivery during refilling of PD.
There is not any HG defrost becuse this liquid enters machine for butter homogenisation. It is continuous process to produce butter and evaporating temp is -15C but for safety reasons (reduced production or something else) there is HG injection point to prevent freezing of butter and stuck of machinery. Each evaporator is eguipped with pressure and temperature controled valves becuse the quality of butter depends on process temperature.
Complete valve stations for each evaporator (lot of different kind are installed there) were Danfoss. Process plant piping diagram I do not have but when I was there before 20+ years I was impressed and I asked about everything. Later on I was there couple of times for some services and use that time to study complete plant.Last edited by Josip; 11-03-2006 at 09:25 AM. Reason: correction of miswrite
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11-03-2006, 03:25 AM #23
Re: Flooded Ammonia Part Two
Josip,
A very interesting system. Thank you for showing it to us.
Best Regards,
US IcemanLast edited by US Iceman; 11-03-2006 at 03:25 AM. Reason: spelling
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11-03-2006, 11:29 PM #24
Re: Flooded Ammonia Part Two
Hi. Ammonia Just love it, The best refrigeration liquid and gas you can use.
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12-03-2006, 08:45 PM #25
Re: Flooded Ammonia Part Two
Hi Guys
I recently designed a system for pumping all the ammonia charge out of a brine chiller on a cheese plant, prior to the tube side being cleaned by a CIP (Clean in place) system. I based my system on the Sabroe "Thermo Pump" used to cool oil in recip compressors.
I thought I have designed something unique
The process was as follows. using motorised valves.
Shut off the liquid and pump out.
Shut the suction off, evaporat pressure reg in circuit
Open a drain valve at the bottom of the chiller to a drain vessel
Pressure with hot gas, whilst opening a vent to the outlet side of the suction press reg
Close drain valve on a low level cut out and stop the hot gas and start the CIP
After CIP the chiller can be ran as normal with the hot gas used to push the liquid from the drain vessel to the main liquid line.
It seems I have seen a drawing somewhere for a pumper system and copyied it without thinking
Still I think pumper systems are a good idea
Kind Regards. Andy.
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12-03-2006, 11:15 PM #26
Re: Flooded Ammonia Part Two
I think the system Andy described is similar to some ice cream machines I have heard about. I can't remember the name, but I believe they German. Apologies to the company if I'm wrong.
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29-01-2009, 10:17 PM #27
Re: Flooded Ammonia Part Two
All I work on is Sullair Refrigeration products, if you have questions contact me at Mid-States Refrigeration.
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30-01-2009, 01:09 AM #28
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05-02-2009, 03:45 PM #29
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