Printable View
hi guys:
I need help.
i need know the procedure for selection the size of the high pressure receiver. it will work in the system of ammonia what parameters i need know.
i'm from peru.... i sorry.. i don't write so good in english ....i hope you can help me.
Hi, luissandoval :)
Welcome to RE forums....
Generally your receiver must be sized to receive complete amount of ammonia within your plant, BUT...maybe you can do something else....depend on design of your plant....it will be better to give some more info....to give you some suggestion...Quote:
Originally Posted by luissandoval
-type of plant
-system/s
-capacity
meanwhile, please, search RE forums...for.. ...ammonia...receiver....NH3....
I'm sure you'll find what you need and then you can come back with more question/s;)
Best regards, Josip :)
The issue with sizing a high pressure receiver relates to the calculation used to determine the total system refrigerant charge. In some pipes you may have liquid and vapor and you need to choose what fraction of the refrigerant is liquid or vapor to find the correct mass.
Then you also have the problem of the actual pump down volume of the receiver. Since the dip tube in the receiver needs to be covered in liquid to supply refrigerant to the system, this volume of liquid occupies some of the available pump down capacity.
The calculations for most of this are simple, but time consuming because of the nature of the problem.
Your receiver should be sized to accomodate the entire charge of ammonia that the system will hold PLUS 20% head space for vapor containment. As per ASHRAE and other standards this will allow for liquid expansion during the warmer months.Quote:
Originally Posted by luissandoval
Sizing the system can be difficult, however, most manufacturers will list the liquid volumes of refrigerant in evaporators and related equipement (accumulators, recirculators, oil pots, etc).
Unfortunately, almost all receivers are NOT sized to hold the entire charge and operators are required to hold excess liquid in chillers, evaporators and vessels which means keeping the engine room on at all times. It also means that you must use pressure regulators on the low side of the system equipped with automatic bypass reliefs to assist in the transfer of excess pressure back to the engine room to stay below the set points of your relief valves.
Hope that this helps! Best of luck!
For a relatively small system charge ( say 3-4 ton of ammonia ) receiver could be sized for the entire charge.
However if you have 20-30 tons of ammonia inside i see not benefit to install a receiver holding that amount.
I select the receiver just to accomadate the changes on the evaporators and piping. For a large system you mostly have several seperators accumulators and thay have some excess volume to be filled .
So when you need to empty large volumes you send the ammonia to these vessels.
For larger quantities you need a tanker.
I am not qualified to give "expert" advice, but I would like to suggest that you look carefully at your various vessels when designing your system to be certain that you have some place to put your NH3 during maintenance so that you don't need to call out an ammonia truck every time you service your system.
I have about 20,000 pounds of NH3 in my system and don't have much capacity to shift the NH3 around during maintenance. I have emptied one of my low pressure receivers this week to replace relief valves and to replace some old piping, and had just barely enough room in another low pressure receiver. I would really be unhappy if my maintenance schedule were determined by the ammonia truck...