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Prashant Kumar
10-03-2009, 10:32 AM
Hi guys.am new to this industry.and am being give a task of computing the required referigeration load for a Vertical Co2 polyeurethane(6" thik) insulated tank.The problem is when continoulsy running the chiller for 8-9 hrs, the pressure drop is negligeble..ie when the Chiller was switched on, the pressure was 21bar and after continously running for 9 hrs the pressure inside the tank was 20.5 bar..
Should it be considered that the chiller used is inssufficient.Can somebody let me know how do i size the unit or the reasons that may be affecting the system
It would be great if you could give me a few inputs..Following are the tank details:
Tank capacity: 10000T
6"thk polyeurethane insulated vertical tank.
Ref: R404A

Prashant Kumar
10-03-2009, 11:41 AM
sorry a small correction..capacity is 10 T and not 10000T..regret the mistake..

NoNickName
10-03-2009, 01:24 PM
Let me try to understand: you have a tank filled with 10 metric tons of liquid CO2 at 21bar (-18C). Is that correct?
What final temperature or pressure do you want to achieve? In how much time?

chemi-cool
10-03-2009, 06:12 PM
CO2 liquid tanks come in 2 insulations: foamed polyurethane and vacuum.

The evaporator is built inside the tank and has no fins, just bare pipes.

Recently I had to find out the cooling capacity for a 10 ton vacuum insulated tank.
It is 1KW at -20C evaporating temp.
If it is insulated with polyurethane, I assume it will be much more.
The manufacturer should know that detail. contact him.

Kp3
10-03-2009, 07:43 PM
u need to get the evap down to -40degrees c. they are static coils and the ones i have installed for 10tons usually have a 2kw condensering unit on them 3phase. usually get a problem with 1phase comp electrics.

Prashant Kumar
11-03-2009, 08:16 AM
Hi NoNickName, .Let me clear it.The Tank Max allowable working pressure is 24bar & hence the required operating pressure is around 18 bar..In order to maitain this pressure we have provided a chiller/ref unit.But inspite of operating this refer unit, the tank pressure is not comming down.Now would like to know what may the factors affecting it..?
Thanks chemi cool...
Hi KP3... Currently we have 4.5KW unit with 3 phase,440V,50Hz...

Also as chemi cool mentioned about the evaporator coil built inside the tank, we did take this coil off from the tank & made modifications by allowing the CO2 gas to pass through the coil inside the chiller having referigerant. Is this clear or you would like to have an attachement indicating the same...

Regds..Prashant

quarterpounder
22-04-2009, 09:09 PM
I've worked on a few tanks over the past year and my understandingis that the condensing units are not meant to pulldown the pressure rather maintain a constant 19-18.5barg.

As the liquid is used it will lower the temperature.

try looking at other reasons

too high pressure in the delivery lorry, normally the driver blows in down unless he's in a rush.

back feed from another tank or process

blow it down to 18bar and see if it maintains in over a few days.


10ton tank is samll 1kw units grand

hope it helps

sterl
24-04-2009, 07:55 PM
If this thing is brand new: Did they FIP the urethane?

If its still curing out you will have a good excess heat load for some time to come!