Long vertical suction line dual risers

Hi guys,

can you please help us with calculating and selection of the suction line for the ice machine
GRAM RIA 10.2? (Pump system - wet return line)
Currently RIA 10.2 is connected without riser and it is located
10 meters below main NH3 wet suction line of the system -45°C and
the main suction line where RIA 10.2 is connected is 20 meters
from vessel -45°C (10m vertical and 20m horizontal pipe).
Liquid NH3 is supplied with TH-WITT pump HRP8050 from vessel -45°C (3:1).
Our client is not always getting temperature of cold brine -40°C, instead they
get temperatures of cold brine from -36°C to -40°C.

I think that the main problem is incorrectly connected vertical suction line
pipe DIN-EN 125 without riser (without botom and top P trap).

In my opinion, for this case, RIA 10.2 suction pipe must be connected with dual risers
because of vertical height of 10 meters and changable capacity.

From ASHREA Refrigeration Handbook (SI) 1994 page 3.26, the velocity in the risers must be 25m/s or higher and on that fact Coolselector2 has selected pipe DIN-EN100 for 70% capacity and DIN-EN65 for 30% capacity.

Are those pipes selected as it should be?
Also attached are tehnical data for RIA 10.2 ice cream machine.


Regards.
Matija

MatijaZGP,
I'm not convinced you need a double riser, as they are for varying loads, do you have varying loads?
Vertical riser might have to be in two steps with shallow traps, as well as if you do require double riser.
Liquid feed in should be very carefully adjusted so as not to over feed to much to log suction riser.
If brine pumps stops etc maybe interlock it to liquid solenoid.
Oil could possibly cause some problems if floating around system , as it cannot return to suction line.

interesting read of specs, coil volume 610 litres, refrig charge 380 litres, confirm it is DX feed or pumped over feed. The riser should be designed for operating design velocities, and agree with Ranger oil logging in coil could be part of problem.

I found shematic from GRAM itself for RIA 10.2 installed in Venezuela as you can see on attached photo. Sadly the vertical high is not written.
Oil is blown to wet suction line when defrost starts, as you can see on the schema.
The RIA 10.2 in my case is connected the same as on this schema, but without dual risers and
P traps top and botom, and the suction pipe is DIN-EN125.
Mostly this RIA operates at full capacity which is 28000 ice cream sticks per hour, but sometimes they slow down do 20000 or 16000 sticks/h, all depends of ice cream type.

Also I have attached technical data for all GRAM RIA ice machines if someone needs it.

Hi
the pipe schematic is hard to read or understand, repeat as a pdf if you can.
A single riser should be ok if expansion vavs are set up correctly, you should have a couple of degrees super heat at coil exit to ensure coil is not totally flooded and you get high velocity vapour all be it super saturated back to surge vessel.

Here are the better photos.
If you can't read the top three main pipes from top to botom one
goes like this: 1. Hot gas, 2. Suction and 3. Liquid.

Update dual risers:

Today RIA 10.2 was put in operation and is working very good.
Before when there was no dual risers they got brine temperature -36°C
and now they have -39°C...-41°C.
The temperature of inlet liquid ammonia is -44°C.

Here is before and after picture of the top P-traps:

Attachment 13984 Attachment 13985

Quote:

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Originally Posted by matijaZGB

Update dual risers:

Today RIA 10.2 was put in operation and is working very good.
Before when there was no dual risers they got brine temperature -36°C
and now they have -39°C...-41°C.
The temperature of inlet liquid ammonia is -44°C.

Here is before and after picture of the top P-traps:

Attachment 13979Attachment 13978

---

Thanks for the update, are you completely happy with result & fine tuning?

I wonder what Gram would supply new today with latest designs, surely it's better!

Yes, we are very happy with the result. (It's important that client is happy also :D)

have you find why it happened?

what was your suction pipe size before ? what is Now ?

if your suction pipe size is small , you have more pressure in evaporator than your suction line therefor you have less temp. or if your liquid flow to evaporator more than your evaporator capacity it give you same result as small suction pipe size ,
in these type of system it is better to put gags between evap. and main suction line.