Gravity liquid/vapor separator to little?

[aphun]

Hi
Im from Peru, i have problems with liquid carryover to suction line compressors in ammonia system for an IQF tunnel, aeroheat model 2010, 2 Mycom N42WB, Gravity Liquid/vapor horizontal separator (2200 mm length x 600 mm dia).
When start 2nd compressor, at 67% capacity, liquid carryover right to compressors. The contractor said the size of the separator is small, need to change for 3500 mm lenght x 1200 mm dia. because when we will load the tunnel could be worse.

is that correct?
thanks
aphun

[aphun]

i forgot diagram

[josef]

Hi Aphun,
600 mm is really little, at least 1000 mm

[RANGER1]

The high pressure liquid level makeup is suspect by your schematic also .
It is close to dry suction, so higher velocities could cause carryover .
Make sure regulating valve is adjusted so it is feeding liquid makeup 70 - 75 % of the time when at max load .
Also make sure liquid reciever has good level so no hi pressure gas blasting into surge drum .

[aphun]

Thanks Josef/Ranger1
Here a contractor thinks if we place a liquid acumulator tank before suction compresors could we avoid that.
But, that means increase the suction length in 10 mts (actual 18mts 5"dia) more, does it afect the suction temperature of the gas in order to get -35ºC in the tunnel?
Thanks
aphun

[RANGER1]

Wont affect temps but you then also have to have heat source to boil off refrigerant that comes back to suction trap .
ie liquid line coil inside suction trap also hi level cut out float control .

[aphun]

Hi Ranger
if the contractor wants to put inside this tank a heater like oil compressor with a level switch, in order to eliminate the liquid every time this turn on?
thanks

[aphun]

Hi
About the liquid carryover, its not the size of vessel; we raise the suction pipe over the level of the LVS, and remove the demister pad inside, instead put drop eliminator; and the problem is gone.
aphun

[US Iceman]

we raise the suction pipe over the level of the LVS, and remove the demister pad inside, instead put drop eliminator...

A demister pad and droplet eliminator (I'm assuming you mean chevron style) both operate with similar velocities therefore, I would think the main issue could be assigned to the suction pipe being too close to the liquid level in the vessel.

If that is the case, then you had insufficient separation distance to dis-engage the liquid form the vapor stream.

[TXiceman]

With out going in and doing a design calculation on your surge drum, I would first look at a few things.

-Liquid level
-where the liquid enters the vessel in relation to suction and liquid level.
-location of wet return
-suction location
-excessive oil in the drum

You would be surprised at the number of so-called refrigeration experts that can not properly design a suction or pump drum.

Ken

[US Iceman]

You would be surprised at the number of so-called refrigeration experts that can not properly design a suction or pump drum.

Now, now, don't be mean.

I agree with you though. Most of the "experts" use rating tables and have no appreciation for the actual mechanics involved.