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Re: Refrigeration System with Ammonia
Your guidance and assistance shall be very mush appreciated as I find that most of you have an expertise in Ammonia systems. Also let me know if Screw Compressors would be suitable for such applications.[/QUOTE]
...You must try ammonia if you use them in industrial purpose...
...and try Sabroe screw compressors 202LF or 283L...
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Re: Refrigeration System with Ammonia
Quote:
Originally Posted by Sinke
...You must try ammonia if you use them in industrial purpose...
I'm not sure I understand what you mean by this. :confused: Screw compressors can work with almost any gas or refrigerant if applied properly.
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Re: Refrigeration System with Ammonia
Screw Compessors are suitable for any refrigerants and conditions. There are a large manufacturers of good screw compressors.
I myself am learning a lot about ammonia from this forum. If I could be of any help to you, please do put in a post so that the experts in this forum will also be able to guide you.
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Re: Refrigeration System with Ammonia
Hello Samarjit Sen
I just finished a project for an Ice Cream Plant using ammonia as refrigerant.
The projets has three suction temperature levels
-10°C,-35°C and -45°C.
-10°C is used for a water IceBank and Chilled water. The Icebank are flooded
-35°C is used mainly to keep the temperature in store room and some proces machines. The Ice Cream should be kept at -28°C so you should evaporate the ammonia at -34°C and 1°C temperatura loss to the compressor. The evaporator in the Freezer are overfeeded 5:1.
-45°C is maily to hardener tunnel They are also overfeeded 5:1
We used to have two stage Recip commpressor and with the new project we move to open screw compressor. The compressor oil is cooled by thermosifon.
The plant will handle 400Tr at -45°C, 350Tr at -35°C and 1400Tr at -10°C.
The plant will work in two stage with intercooler.
I hope this comments will be helfully for you
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Re: Refrigeration System with Ammonia
Hi gwapa,
That seems like a nice project.
Are you using the -10°C as your intercooler temperature?
Also, if I may ask... why did you use a 5:1 circulation rate?
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Re: Refrigeration System with Ammonia
Hello Gwapa,
Thank you for the information. I shall be more than grateful if you could please give me more information on the system. We have executed similar projects with R 22. Now I am interested to use Ammonia, and as such your informations would be of great help.
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Re: Refrigeration System with Ammonia
Hi Us Iceman
It is nice to greeting you all
Yes ,I am using the -10 °C as intercooler temperature. This is a flash intercooler. It also has an sideload conection to handle the load coming from -10°C .That is the Ice Back and water Chiller. So the intercooler works as a knock down vessel too.
The truth is that 5:1 overfeed is a mean value. There are some process machines using 6:1 and evaporators 4:1.
My expirence is that when we have several evaporator in paralle operation in diferentes applictions one has to pump ammonia for the installed load and not to the pick calculated load. Let me explain my self. If you have a pick load of 100Tr. but you have installed evaporator for 120Tr then one should pump ammonia for 120Tr.What do you think?
By the way US Icemann and all the experts in the forum, the intercooler is a big tank 2,00 m x 4,5 m. It is horizontal shape
I ask to the provider in order to make the diameter smaller,but I have not had any lock . Do you have the designg parameter for an intercooler?. That is the residence time of the ammonia hot gas bubbles into the liquid.
What will be the gas speed leving each hole in the distribution pipe?
Again nice to hear from you all
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Re: Refrigeration System with Ammonia
Hello Samarjit Sen
It is glad to help you in any question regarding the Ice Cream Plant project using ammonia
Best regards
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Re: Refrigeration System with Ammonia
Gwapa, size the intercooler based on the gas velocity per ASHRAE or use Stokes equation. I never exceed 80% of the calculated velocity for an intercooler of suction side vessel.
As for the distribution of the hot gas under the liquid, I use a perforated plate in the bottom of the I/C and distribute the gas under this plate. I use a total hole area that is about 50% of the area of the vessel (vertical vessel). For the liquid out of this vessel, I leave a portion of the plate without perforations and build a weir About 12" high and let clear liquid settle there and take this liquid to the rest of the system.
Since the liquid level will lift from the gas distribution in the bottom at start up, you need to make sure you have enough height between the operating level and safety shut down level.
Another way to do this is to take your discharge pipe to the bottom and cap it. Them use perforations in the side of the pipe....about 2 times the pipe area for the total hole area.
In either case, you will need to have a anti-siphon hole in the top of the inlet elbow inside the vessel. This will equalize the pressure and keep liquid from backing up in the discharge pipe at shut down conditions. Usually about a 3/8 to 1/2" hole will do OK.
Ken
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Re: Refrigeration System with Ammonia
Horizontal intercoolers are more involved for design requirements than a vertical vessel I think. The depth of the liquid pool in a vertical vessel tends to be higher than what is found on a horizontal vessel (if you do not want loose your surge volume).
This problem becomes worse if you try to install refrigerant pumps under a vessel being used as an intercooler also.
It can probably be designed around to work OK, but I would prefer to use a vessel for separation and do the intercooling in the booster discharge line prior to the vessel.
On the horizontal intercoolers I used a similar approach to TXiceman, but on the sparge pipe I used a 45° arc of holes across the bottom of the pipe. This allows a lot of the surface area of the pipe to be used and it places the holes closer to the bottom of the vessel.
The perforated plate is critical. This should be a mandatory requirement to prevent jets of liquid being pushed up into the vapor space.
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Re: Refrigeration System with Ammonia
TXiceman / US Iceman Thanks for your tips
The anti-siphon hole in the top of the inlet elbow inside the vessel is very import
Thanks again
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Re: Refrigeration System with Ammonia
These are the items and tips you do not find in books. Similar to using vortex breakers in other vessels.;)
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Re: Refrigeration System with Ammonia
Quote:
Originally Posted by
US Iceman
These are the items and tips you do not find in books. Similar to using vortex breakers in other vessels.;)
I grew up in a loging camp next to a hydrodam and a fish hatchery, and seeing how the water would form vortexes at every chance/ fast forward to now/ I all ways wondered how they dealt with any vortexes that would form in the ***** systems! Especialy the larger receivers!? Neat how they do it with the NH3.
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Re: Refrigeration System with Ammonia
I use the same type vortex breaker in ammonia or "*****" systems. But you do need a vortex breaker at every liquid outlet of a vessel, whether it is to a pump of let down to another vessel.
Ken
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Re: Refrigeration System with Ammonia
Hello Samarjit Sen
I would recommendate a two-stage-system with CO2 as lowstage refrigerant and ammonia in the high stage circle. You can design a DX system if have some coldstorage application and a flooded system for freezing tunnels. If you built a flooded system with CO2 watch out for the oil return concept, because compressoroil is in general terms miscible with CO2.
Best regards
Rinaldo1Z from Switzerland:)
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Re: Refrigeration System with Ammonia
Welcome to the RE forums Rinaldo1Z. Can you tell us what type of work you do in Switzerland? You can post your reply in the Introduction area of the site.
Look forward to seeing future contributions from you.
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Re: Refrigeration System with Ammonia
Hi Rinaldo1Z,
Sorry for the delay in replying. We do not have many plants of CO2 in our country, but there is a project where Ice Cream is to be hardened and subsequently stored. The hardening tunnel will be at -40oC and the Storage at -30oC. I would like to use CO2/NH3 for this application.
Can anyone provide me with a schemetic diagram for the this system. It is like any other cascade system, but what I would like to know are the safety features and the equipments to be incorporated.
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Re: Refrigeration System with Ammonia
Dear Mr.Sen
You are intending to harden the ice cream. The recomended temperature for the same is -40 deg.C and even below. -25 to -18 is the preservation temperature of the hardened ice cream.
Size of the each batch and the production of the ice cream per day will decide the type and the size of the refrigeration system to be employed.
you should specify the same.
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Re: Refrigeration System with Ammonia
Dear Mr. Varde,
Ice Cream starts hardening from -18oC core temperature. Generally the Hardening Rooms or the Hardening Rooms are maintained at -40oC. At this temperature usually the hardening is completed within 6 hrs time if not earlier. We have installed some Hardening Rooms with R 22 system and had no problem.
I am now interested in using CO2 as the refrigerant for the hardening chambers. I am seeking information on this and other than the forum, I have collected informations from other sources.
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Re: Refrigeration System with Ammonia
Quote:
Originally Posted by
Samarjit Sen
What I had referred was semi hermetic SCREW compressors.
No I am not going to make any component myself. I would like to procure these from the regular manufacturers.
Please let me know using screw compressors would be suitable and are they suitable for such applications. I am completely depending on you all to help me out, as I have always done good jobs and am known for the same. Till now I have worked on all refrigerant other than ammonia, and as such would like that in case I take it up, it has to be done in the best way.
Dear Samarjit,
You can go for open type screw compressor of single stage machine or two stage reciprocating compressor with flooded type evaporator. You can source evaporator & compressors from OEMs .other shell & tube condenser and receiver can be source localy but manufacturing standard should be compile with ASME CODES.
THANKS
Ramesh Mysore
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Re: Refrigeration System with Ammonia
Hi Ramesh Mysore,
It is nice to have you here. I am trying out the various application and learning the system with Ammonia. As you know in our country, Ammonia System mis still pretty old, due to which there are frequest failures. In this forum you will find members who are vary learned and helpful.
I have also noted your suggestion. Please PM to me your contact number.
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Re: Refrigeration System with Ammonia
Hello Mike,
It is a old thread and more to my present requirement. At present we propose to use a single two stage ammonia compressor with two evaporators. The defrost system we propose to use is electrical. The Evaporators are from Kuba, Germany. These Evaporators have bottom feed.
In the drawing attached in this thread, you shown a drawing with top feed. Should there be any change.
Need your assistance for making the layout.
Thanks in advance
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Re: Refrigeration System with Ammonia
Quote:
Originally Posted by
Samarjit Sen
Will you please advice me as to who are manufacturing two stage ammonia recip. compressors. Generally what I have seen in our country, they use two seprate compressors one for the high stage and the other as the booster.
Since I am new in ammonia I shall follow the advises from you all of the forum.
Dear Samarjit Sen,
GEA Grasso makes two stage ammonia recip. compressors. And this compressors
has well proved to be in our country.
Grasso's recip. compressors are fully welded, the main advantage of this type of construction is the absence of water cooling on the compressor resulting in lower investment and running costs. The externally positioned “air cooled” cylinders make use of natural heat dissipation by means of convection & radiation. At present, when the price for water is expensive enough, this condition is one of main in a choice of the compressor.
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Quote:
Originally Posted by
PVA
Dear Samarjit Sen,
GEA Grasso makes two stage ammonia recip. compressors. And this compressors
has well proved to be in our country.
Grasso's recip. compressors are fully welded, the main advantage of this type of construction is the absence of water cooling on the compressor resulting in lower investment and running costs. The externally positioned “air cooled” cylinders make use of natural heat dissipation by means of convection & radiation. At present, when the price for water is expensive enough, this condition is one of main in a choice of the compressor.
Sorry to inform you, that dear Samarjit is no longer with us on this world!
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Re: Refrigeration System with Ammonia
i am new at this forum, and has followd this topic.
i have a great interest in NH³ , and want to now how this story has ended.
wat kind of compressor was aventualy used, is there a drowing we can see, or the explaned setup for this particular plant.
wat is eventualy the outcome??:)
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Re: Refrigeration System with Ammonia
Quote:
Originally Posted by
nike123
Sorry to inform you, that dear Samarjit is no longer with us on this world!
Oh... it's not good,
thank you for information.
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Re: Refrigeration System with Ammonia
I would like to ask if You have any catalogues with technical data for freezing tunnels and if yes, can You provide these catalogues for me. If not, can You please tell me or give me directions where I can find the information I need.
Thank You in advance
.
Regards,
eng. Miroslava Rasheva
:D
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Re: Refrigeration System with Ammonia
Hi all, pls can anybody explain to me what is the pump rate for example 5:1, 4:1
Thanks
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Re: Refrigeration System with Ammonia
Quote:
Originally Posted by
nafiz
Hi all, pls can anybody explain to me what is the pump rate for example 5:1, 4:1
Thanks
5:1 Pump supplies 5 units of liquid ammonia to the evaporator. 1 unit evaporates, 4 units go back to the receiver.
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Re: Refrigeration System with Ammonia
Quote:
Originally Posted by
Samarjit Sen
Thank you Iceman. The total refrigeration capacity shall be about 30 TR. There shall be in all 6 nos. of evaporators. 3 shall be maintaining a temperature of -40 Deg. C and 3 will be for -30 Deg. C inside the room. What would you recommend.
30 TR not worth to go to ammonia and flooded system you can use dx system, however if you read frick bulletins from york can giveyou a good guidelines for the custom engineered systems, you have to select compressor, then condnser (heat of condenser equal compressor power plus refrigeration inyour case 30 TR =100 kw,
you have to select receiver, surge or recirculated vessel (equivalent to throttling)
as a rule of thump (two third of reciver volume =condenser volume + evaporator volume and 10% for tubes)
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Re: Refrigeration System with Ammonia
[QUOTE=Gaafar;168749]30 TR not worth to go to ammonia and flooded system you can use dx system,
It's often more economical over the life of a system to use ammonia even for 100 kW. Over the years, I've built several 75 kW flooded ammonia systems economically. In fact I built 3 or 4 systems of about that size in Saudi back ion the late 90's.
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Re: Refrigeration System with Ammonia
Quote:
Originally Posted by
Miroky
I would like to ask if You have any catalogues with technical data for freezing tunnels and if yes, can You provide these catalogues for me. If not, can You please tell me or give me directions where I can find the information I need.
Thank You in advance
.
Regards,
eng. Miroslava Rasheva
:D
Dear Miroslava Rasheva,
If you need freezing tunnels you can look next companies:
Aerofreeze Systems
http://www.aerofreeze.com/en-ca/Pages/default.aspx,
Eurotek Engeneering
http://www.eurotek-eng.co.uk/
Intec
http://www.intecvrt.com/