I am looking for more details on selection of Liquid Ammonia Pumps & the system. Infact if there are any articles on this, that shall be very useful. What are the Flow rates recommended through coils, plate freezers etc.
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I am looking for more details on selection of Liquid Ammonia Pumps & the system. Infact if there are any articles on this, that shall be very useful. What are the Flow rates recommended through coils, plate freezers etc.
Hi, smpsmp45 :)
Please check this thread:Quote:
Originally Posted by smpsmp45
http://www.refrigeration-engineer.co...erfeed+systems
or even better: click the Search button and then write down what you need (pumps, overfeed, system, ammonia etc).....need some time to read answers, but for sure less then we used to write them;)
Of course someone can come with some other link/s....
Best regards, Josip :)
Normal circulation rates for pump sizing on ammonia are 4:1. This provides an overfeed rate of 3:1 for the evaporators.
What this means is the pump is selected for 4 times the refrigerant boil-off rate of all the evaporators connected to that pump at 100% capacity.
At 100% capacity the refrigerant exiting the evaporator will have 3 parts liquid and 1 part vapor with a 4:1 circulation rate being feed into the evaporator.
Many thanks for the proper reply. I shall study all the material available & may be even I can write a small note for all.
http://www.ior.org.uk/ior_/images/pdf/general
PL. check this out for Ammonia Pump Guidance details
smpsmp45,
The link you posted is a members only link I believe. You might want to check this.
No, I could get a print out of that file. If needed I can send it. I am not sure if It can be posted on this site. There are almost 18 pages
If the file size is less than 100 kb, then you can post it in a thread. Otherwise, you will have to resort to sending copies by email.
The attachment file sizes are limited due to the volume of information contained on this site.
I can't download this link and I'm interested in it.
The file is 950kb size. I think I shall have to send it to those who are interested by mail? is there any other way?
Indeed, posting it on Megaupload.com, it's free and the files may be very large.
You will receive afterwards a link which you have to post here.
Smpsmp45 send me the pdf file.
This is the link to Megaupload. It will stay there for only 14 days after the last download of someone.
http://www.megaupload.com/?d=TPQCMSMT
Thanks for sharing the file smpsmp45, and also thanks to Peter for uploading it on the web.
I have read this quickly and it appears to be a good paper. The only thing I did not care for was the mention of putting strainers in front of the pump. It makes perfect sense to say this as you want to keep debris out of the pump.
However, this also adds pressure loss to the pump suction and reduces the available NPSH. While the use of a strainer in this location solves on problem, it also creates another.
What do others think?
I wouldnt do it myself, all of our pumped liquid lines have strainers on every valve group which will catch any trash coming from the pump anyway, just something else you would have to check / clean if there were problems.
I looked that over quickly, and it suggested that a strainer before the pump may cause problems with NH3 systems.
I could guarantee it would.
I try screening a ventilation fan years ago in a processing plant. It was amazing how how much performance suffer with any kind of meaningful screen.
Imagine the scenario where you shut down a pump recirculated NH3 system that has not had oil drained properly for some time. It can take hours to get a restart. Now imagine the thick oil trying to move through the screen.
R-22 systems might do much better, however I would think this is still looking for trouble.
I have heard of several large R-22 liquid overfeed systems that had strainers placed in the pump suction. They had problems too, because of the oil and wax collecting on the mesh at low temperatures.
I could possibly see a use for a strainer in the pump discharge line to catch a lot of the junk. Being on the discharge side does not cause problems for the NPSH requirements. This might also make it a little easier for maintenance and start-up problems.
I have already sent the PDF file to Mr. peter christia. & he is going to use Megaupload.com for all to use that
Oh Sorry, My msg was meant for earlier days. But by mistake it was posted today.
I also checked the Manual of Pumpen- German Pump manufacturer. They recommend Strainer during commissioning stage & later insist to be removed. We in our other plant had provided the strainers, but after reading the manual, removed the strainers & yes, the performance did improve. The operators were always suggesting to remove the strainers in the first place.
I can certainly understand why the pump manufacturers request the suction strainers. It helps to protect their pumps from physical damage caused by debris.
Unfortunately, the additional pressure loss caused by the strainer causes a lot of problems when pumping a volatile fluid at it's bubble point.
My vote is with the operators to not use them. For a system start-up situation the more you can do to keep the system clean during installation will pay huge savings.
A strainer used in the pump discharge line is easier to change than a lot of smaller strainers out by the evaporators too. You still need the strainers on the liquid line solenoids and pressure regulators and need to keep them clean. However, the strainer in the pump discharge line is easier to clean because it is more accessible.
Noting is a complete solution to the problem unfortunately.:o
It is interesting to read this article rom a distinguished member of IIAR. He has written no of articles in Ashrae journal on this issue & has ben reently awarded life membership by IAAR
This discussion of Strainers in Pump Suctions is interesting. Since I do not apply them it is mostly theoretical.
However I was out of town Monday and would be passing by a Plant I had done work for in the past. The Manager had invited me to stop by and see the new 1000HP (NH3) Blast Freezer they were having installed by another contractor.
As is common in this area, the out of state Contractor had hired a local Mechanical Contractor to do the actual installation. (It is difficult here to meet the State Requirements.)
Since the Manager was not in I explained who I was to the Foreman and was allowed to wander around a bit, although they were a bit cautious.
Looking at the LPR I noticed several things that seemed a bit strange.
The Hermetic pumps were mounted fairly high on the Drop Leg. And there were what appeared to be 90 degree strainers close coupled to the Pump Inlets.
Not wishing to push the limits of my welcome I merely confirmed with the Foreman that they were indeed strainers.
Now it may be that they intend to remove the strainers after the initial start, although the wisdom of having a 90 degree turn close coupled to the pump is a question.
I will try to stop by in the near future and see how this works out.
I want that file, could you send to me by email? My eamil is XXXX.
Thanks!
I can't download this link too!
In order to have a summerised view of the basic issue & various answers to those points . I have pre[ared a summary in Q& A format. Few of the answers were received from variopus experts right from Denmark to USA. Few even from our forum.
But to have a clarity on the basic issues, I think my summary of Q & A format should help all.
Few answers are extraploated based on forum views too.
I have printed out the PDF and will look at it over the weekend.
Dear US ICEMAN
I was eagerly waiitng to hear from you on that
Ooops. I forgot. Sorry.:o
I will try to read it ASAP.
I am in need of branded liq ammonia pump selection chart with datasQuote:
Originally Posted by smpsmp45
Well, flow rate has to be calculated as per different project wise and designed. Looking for personal datas.Quote:
Originally Posted by Avtar S Bhui