Hi, RichardB777

welcome to RE forums ... maybe you can tell us a little more about yourself, later ... here .. http://www.refrigeration-engineer.co...p?72-New-to-RE

Quote Originally Posted by RichardB777 View Post
Hello,
We are planning to install a second refrigeration plant. It will work with the other one, sharing the same vapor, liquid and hot gas lines. It is a propane refrigerant system. Has anyone worked or is working on a similar system? What are some of the things to note? I can not find much info
through process books. The part I'm trying to work through is the controls. One system is three centrifugal compressors the other system will be two screw 1600 hp. They'll be two hundred meters apart, with the chilling trains between. The new system will have all the vessels and condensers of its own. So far as control, on suction pressure or one base load and the other swing. Caution or question, is receiver levels balance? There is no hot gas BP around the CW condenser, or will be. On thing I have found out is our new receiver pressure will be 1300-1400 kPag (winter-summer).
For simplicity I only put down two chillers. The duty in the existing system is 4500KW @-15, which does fluctuate in the summer and winter. The new addition it will
change to 10000KW @-25.
Thank you,
very interesting project ... definitely not simple to solve...

I am working for many years with similar systems, but all of them are custom made and unfortunately you cannot find a lot of info on the WWW ... With all my respect, what I saw many times are copy&paste projects with the same mistakes from day one ... this is refrigeration plant within petrochemical plant and approach must be from refrigeration point with best possible COP...

I must admit I am a little bit lost between your numbers ... OK, English is not my mother tongue and maybe within translation something is lost ... anyhow, i believe you can put some light on the "gray" zones ...

Your existing system is about 4,5MW working @-15*C (1,91barg)...
new system will change all to total of 10MW !?!, but second system will work @-25*C (1,03barg) that means you are planing to install two (2) screw compressors (I suppose) each with electric motor of 1600 hp (1190kW)...

I am not sure how you plan to connect two refrigeration systems with different suction pressures to the same chiller trains (maybe I misunderstood something?) ... you can install back pressure valves, but that is not easy to control ... you have two control loops (loop within loop) and then that became a problem ...

What type of economizer you are planning to use (probably open flash - because you have refrigerant recirculation pumps) ... probably better will be S&T type economizer ...

In general regulation of refrigeration system is the best with refrigerant pressure ... temperature signal is too slow ...

I do not understand your question regarding receiver levels? You can level them with pumps and check valves, but with lot of level controls and of course lot of problems...

What type of oil cooler you are going to use?
What type of refrigerant condensers you are going to use ... air, water or EC?

I believe you can give us answers in a simple way ... without your good description we are blind.

Sorry, about so many questions, but to be able to give some suggestion i.e. help we need to know "idea" of your system quite good.

Best regards, Josip