Thermosyphon oil cooler pipework

[seanf]

Have a system with thermosyphon oil cooling for three compressor skids. On the discharge pipe at the condensers the three thermosyphon pipes join into their own header, and from the header into the discharge pipe before it goes to two condenser. See badly drawn pipe diagram.

Green arrow - discharge to condensers
Red - stop valve
Orange arrows - thermosyphon oil cooler pipes (piped into top of discharge)
Blue arrows - to condensers (piped into side of discharge running horizontal)



On the discharge pipe where the thermosyphon header connects, there is a horizontal pipe loop (drawn as below discharge pipe) with a stop valve, with its connection either side of the thermosyphons connection to the discharge.

Just interested to know what this loop with shut-off is for?

Im guessing its to control flow through the thermosyphon oil coolers, by increasing the discharge pipe cross-sectional area to reduce discharge velocity, and so increasing static pressure seen by the thermosyphon pipe.

Cheers

[RANGER1]

seanf,
Can you draw in all the pipe sizes?

Would be interesting to measure discharge temperature before & after this "trap" as from your sketch it looks like a place to pool liquid on condenser inlet.
Sabroe pipe similar to this way. but they probably pipe in everything to above condenser inlets.

This does not answer question, but good link below.

070.900-E Thermosyphon Oil Cooling R-717 & R-22 (johnsoncontrols.com)

[seanf]

Hi Ranger,

I'll try and get the pipe sizes tomorrow. There roughly - 12" discharge, 6" loop with shut-off, 6" thermosyphon header to discharge, 4" thermosyphon risers.

Sorry its not a trap, the condenser inlets are from the side of the discharge pipe running horizontal. Just my cr4ppy drawing pointing them up. Thermosyphon pipes are above discharge and connect in the top.

Cheers

[Josip]

Hi seanf,

your scheme shows the good way how to make easy money .... by installing 2 pieces of 6" ellbows with 6" stop valve and some 6" pipe (valve is just of a nice size and installed in nice place to use it as regulating valve to reduce dicharge velocity)

That 6" loop for sure can increase internal cross-section in that part of piping and affect gas velocity but why?

Who and when will go up to condensers and use 6" valve for regulation ... .... why is necessary to reduce velocity in discharge pipe that I do not know .... but maybe you can find out ... and share that with us ... maybe I am wrong and what I know about is out of date.


Usually when oil cooler and pipes are properly calculated and installed there is no need for additional help (as far as I know) ... those systems are working for decades without problems, because there are no valves and those systems are self regulated i.e. regulated with regulation of condenser/s.


Another wrong installation (in my opinion) is to connect discharge oil-cooler pipes into comon header and then into header going to condensers ... each oil cooler outlet pipe should be connected from top directly to condenser header ...


Unfortunately it is not possible to upload some GRAM-JPG files showing suggestions how we did that job in the past ... all my files are too big ... I'll try to reduce JPG sizes and upload them later ...


Best regards, Josip

[Josip]

Hi seanf,

as promised before here are two reduced jpg files ...

First one is showing detail connection of oil cooler discharge pipe into main header going to condenser/s ...
THOC_78 red.jpg

Second one is showing multiple oil coolers connected separately into main condenser/s header
(just imagine that instead of thermosyphon receiver we have condenser/s, of course all other piping will be as needed for condenser/s)

THOC_83 red.jpg

Unfortunately, that big loop of 6" still is enigma ...
not found any explanation within my documents ...


Best regards, Josip

[seanf]

Thank you Josip.
I will take another look through the paper work on site and see if there is anything in there about it.