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Tycho
02-11-2015, 08:00 PM
So I just got back from Poland after commissioning the 110tons/24hr system on a factory trawler.

Almost done that is, filled the system and got it signed off by the class agency (Dnvgl), when the ship comes to Norway in three days we'll be running endurance tests and cleaning all the filters.

As some might remember I started the installation the first week of september, and was supposed to go back for an inspection after 3 weeks, this didn't happen because I gut stuck on a service job that kept me in Las Palmas for 5 weeks :)

So the first thing I did when I came on board was to have a pipe rebuilt. I'm attaching some pictures and 10 points to whoever spots which pipe I had to have rebuilt :)

https://drive.google.com/open?id=0B3LHul15B8u9QUM3OENRTFVOUDA

Grizzly
02-11-2015, 09:52 PM
That will be the Liquid Pump Differential gauge lines!
As to any others- Hey>
I am only human.
You Nordic chaps do like to cram in a lot. I have a site I have been involved with recently where the Danish Consultant has never heard of "Best Practice".

Not you or your colleagues, my friend.
Grizzly

Tycho
02-11-2015, 11:12 PM
That will be the Liquid Pump Differential gauge lines!
As to any others- Hey>
I am only human.
You Nordic chaps do like to cram in a lot. I have a site I have been involved with recently where the Danish Consultant has never heard of "Best Practice".

Not you or your colleagues, my friend.
Grizzly

I give, those had to be re done because the insulating crew stepped all over them :)

However there was a major rebuild that had to be done because it wasn't safe for the operation of the system ;)

a hint, it has to do with the economizer ;)

Tycho
02-11-2015, 11:13 PM
That will be the Liquid Pump Differential gauge lines!
As to any others- Hey>
I am only human.
You Nordic chaps do like to cram in a lot. I have a site I have been involved with recently where the Danish Consultant has never heard of "Best Practice".

Not you or your colleagues, my friend.
Grizzly

hahaha, you should tell the danish guy to stop being danish and do it the Norwegian/proper way :D

Tycho
02-11-2015, 11:19 PM
oh and I just got a phone call from the ship owner that the insulation guys drilled a hole in an ammonia pipe...

this is still a mystery to me, if you are working with drilling holes in 0.5mm steel, how do you manage to drill a hole in a 4.5mm black steel pipe???

it has happened to me twice in two months and I am still baffled :D

RANGER1
02-11-2015, 11:52 PM
I give, those had to be re done because the insulating crew stepped all over them :)

However there was a major rebuild that had to be done because it wasn't safe for the operation of the system ;)



a hint, it has to do with the economizer ;)

Could it be no pressure regulator on economiser suction to compressor?
Can only see ICS with EVM.
Or is it something to do with isolation of subcooled liquid & small non return valve to allow for expansion of cold liquid?

Tycho
06-11-2015, 05:22 PM
The economizer suction pipe was laid from the top of the economizer tank and then down to the deck, then back up to the compressor again. making it a perfect place for condensation to occur and shoot it into the compressor :)
Also the NRV valve was placed 2 meters from the economizer port on the compressor, also making it a perfect place for oil to gather during low capacity operation, just waiting to be mashed back in :)

About the pressure regulator, it's done a bit backwards here, there is an AKVA between the top of the economizer and compressor suction, so if the pressure in the economizer is to high the AKVA will open and bleed the pressure down and not open the main ICS valves until the pressure in the economizer is at the setpoint.

Tycho
06-11-2015, 05:27 PM
oh and I just got a phone call from the ship owner that the insulation guys drilled a hole in an ammonia pipe...

this is still a mystery to me, if you are working with drilling holes in 0.5mm steel, how do you manage to drill a hole in a 4.5mm black steel pipe???

it has happened to me twice in two months and I am still baffled :D

Not me drilling a hole in a pipe, but insulation guys :) same thing happened in las palmas, the guy drilled a hole in the main return line and taped over it with aluminum tape. luckily I had just started the system and pulled down the pressure, but it took me 6 hours to get the line closed of (23 plate freezers) and the pressure down so it could be welded

RANGER1
06-11-2015, 09:56 PM
The economizer suction pipe was laid from the top of the economizer tank and then down to the deck, then back up to the compressor again. making it a perfect place for condensation to occur and shoot it into the compressor :)
Also the NRV valve was placed 2 meters from the economizer port on the compressor, also making it a perfect place for oil to gather during low capacity operation, just waiting to be mashed back in :)

About the pressure regulator, it's done a bit backwards here, there is an AKVA between the top of the economizer and compressor suction, so if the pressure in the economizer is to high the AKVA will open and bleed the pressure down and not open the main ICS valves until the pressure in the economizer is at the setpoint.

Interesting, as on land probably unlikely to be piped like you explain.
Economizer line close to compressor if no gas flow can be a bit of a hot spot, so more pipe between stop check & compressor could also be a problem as well.
I think I would feel very vulnerable working on these plants, especially if a leak that was a bit out of control.
A little bit of ammonia goes a long way in confined area.

Josip
08-11-2015, 06:35 PM
Hi, Tycho


The economizer suction pipe was laid from the top of the economizer tank and then down to the deck, then back up to the compressor again. making it a perfect place for condensation to occur and shoot it into the compressor :)
Also the NRV valve was placed 2 meters from the economizer port on the compressor, also making it a perfect place for oil to gather during low capacity operation, just waiting to be mashed back in :)

About the pressure regulator, it's done a bit backwards here, there is an AKVA between the top of the economizer and compressor suction, so if the pressure in the economizer is to high the AKVA will open and bleed the pressure down and not open the main ICS valves until the pressure in the economizer is at the setpoint.


Agree with you regarding piping to Eco port ... pipe must come from top and NRV should be close as posssible ...

And for sure ... during installation works there must be someone (when disposition drawings are not good) to take care about piping and some other sometimes small, but very impotant things ...

One thing is not clear to me ...why you use AKVA and ICS .... As I know when start compressor eco port on compressor is under suction presssure ... when slide valve passes eco port (capacity > 60-70%) then we have intermediate pressure and this pressure is self regulated according to suction pressure ... is there some particular reason to regulate economizer pressure ...

I have now a similar case with propane - for process cooling .. where suction pressure we keep at 0,7 bar (-30*C) for direct cooling, but suction from economizer is at 3 bar (-5*C), because delivery of too cold liquid into one HE is not good for process - actally we have suction return lines from 3 HE working under different parameters. It is also a little strange design of refrigeration plant but ... it is installed and now we have to start it up...


Best regards, Josip :)

Tycho
13-11-2015, 03:11 AM
What we have is a closed economizer tank, previous experience with an open economizer tank left us with too many problems with level control... anyways.

This system has a closed economizer, liquid is fed into the tank from the receiver, and liquid going from the receiver to the liquid tank is passed through 50 meters of pipe coiled inside the economizer tank.

what happens is as the compressor is started and as it works it's way from 10 to 100% capacity, the liquid in the economizer is heated to condenser pressure, so if the ICS opens at this point, we are pumping 10 bar pressure into the economizer port, and bringing the compressor motor to it's knees.

So there is a bleed valve from the economizer tank to the compressor suction to help bring the pressure down to a suitable level instead of kneeling the compressors.

It could as well have worked with a CVPP or whatever it is called, but this is the solution that has been chosen, and I don't have a say :)

RANGER1
13-11-2015, 09:30 AM
Tycho,
Any reason you know of as to not use PHE economizer?
less liquid in system, compact, maybe cheaper.
Just a thought
Put it in suggestion box at work, see what engineering department say.

Tycho
30-11-2015, 08:46 PM
Tycho,
Any reason you know of as to not use PHE economizer?
less liquid in system, compact, maybe cheaper.
Just a thought
Put it in suggestion box at work, see what engineering department say.

I know what the engineering department would say to a PHE, and from the designs I have seen, I am prone to agree with them.

You would need some kind of thermostatic expansion valve on the cold side (compressor economizer suction) to control the superheat through the economizer PHE, and unless you have a very stable liquid feed from the HP receiver to the LP receiver (through the economizer), you will get a very erratic economizer pressure, as I see it, and very little subcooling of the liquid from the hp receiver as it passes through the PHE to quickly.


While the tank we are using has might hold 100 kg of nh3, it has 50 meters of pipe coiled inside that are submerged in liquid -20 - -15 liquid, so even when the compressor is working with full slide, but low load on the system, we still get subcooled liquid and a higher load on the economizer port.


if that makes sense :)

RANGER1
30-11-2015, 09:02 PM
I know what the engineering department would say to a PHE, and from the designs I have seen, I am prone to agree with them.

You would need some kind of thermostatic expansion valve on the cold side (compressor economizer suction) to control the superheat through the economizer PHE, and unless you have a very stable liquid feed from the HP receiver to the LP receiver (through the economizer), you will get a very erratic economizer pressure, as I see it, and very little subcooling of the liquid from the hp receiver as it passes through the PHE to quickly.


While the tank we are using has might hold 100 kg of nh3, it has 50 meters of pipe coiled inside that are submerged in liquid -20 - -15 liquid, so even when the compressor is working with full slide, but low load on the system, we still get subcooled liquid and a higher load on the economizer port.


if that makes sense :)


Fair enough, probably cause more trouble than it's worth.

Tycho
10-12-2015, 10:56 PM
On a side note, we have finally started using AKVA valves with a PID controller instead of a TEAT valve on our systems with LRI, as was suggested here on RE :)

Took a while, because after "airing" the idea, the guys in the office needs time for us technicians to forget that we brought it up, so they can implement it as their own idea :)

But it works like a charm :)

Føroyar
22-12-2015, 07:37 PM
oh and I just got a phone call from the ship owner that the insulation guys drilled a hole in an ammonia pipe...

this is still a mystery to me, if you are working with drilling holes in 0.5mm steel, how do you manage to drill a hole in a 4.5mm black steel pipe???

it has happened to me twice in two months and I am still baffled


Norwegian guys ?

Tycho
22-12-2015, 11:58 PM
oh and I just got a phone call from the ship owner that the insulation guys drilled a hole in an ammonia pipe...

this is still a mystery to me, if you are working with drilling holes in 0.5mm steel, how do you manage to drill a hole in a 4.5mm black steel pipe???

it has happened to me twice in two months and I am still baffled


Norwegian guys ?

I'm Norwegian, the owner is Norwegian, and while I was on the plane back home I got a call from the ship owner
where he sounded panicky, rightfully so,because some dumbass guy working for the insulation company maaged to drill a hole in in a pipe leading to the discharge (pilot receiver)... lucky for them, I had emptied the discharge side of the plant into the low pressure side of the system, so it had low pressure.
Also the crew on board knew what to do.

Førøyar guy, probably, all the guys that made the problem were guys from the feroe islands ;)

Glenn Moore
23-12-2015, 01:12 AM
Hi Tycho
Glad to hear you now use the AKVA in place of the TEAT valve . Used with the EKC 319A controller or similar its control is far more stable, leading to less foaming of the oil and less carryover. It took me a long while to convince Danfoss industrial guys of how good its control was before they would even put it in the catalogue.
The EKC319A was first designed for use as a de super-heater system for low temp Maneurop Scroll compressors but I then first sold the idea to J&E HAlls for their mono screw, to replace the temperamental TEAT valve and helped them install some to make sure it worked OK. I even made a conversion guide from TEAT to AKVA for customers.
Nice to know someone else is now using a nice user friendly control and benefitting from it.
Best Regards Glenn

Tycho
25-12-2015, 08:47 PM
Hi Tycho
Glad to hear you now use the AKVA in place of the TEAT valve . Used with the EKC 319A controller or similar its control is far more stable, leading to less foaming of the oil and less carryover. It took me a long while to convince Danfoss industrial guys of how good its control was before they would even put it in the catalogue.
The EKC319A was first designed for use as a de super-heater system for low temp Maneurop Scroll compressors but I then first sold the idea to J&E HAlls for their mono screw, to replace the temperamental TEAT valve and helped them install some to make sure it worked OK. I even made a conversion guide from TEAT to AKVA for customers.
Nice to know someone else is now using a nice user friendly control and benefitting from it.
Best Regards Glenn

The biggest problem with the TEAT valves were that 70% of them were faulty, and the first thing we'd have to do after charging the system was to replace the thermo part of the TEAT.
The ones the actually worked keeps working for years and years.
Never really had any problem with foaming of the oil, but I'm really satisfied with how the AKVA works :)

Merry Christmas :)

RANGER1
25-12-2015, 09:41 PM
We hardly do liquid injection at all, but the few I have been involved with, we used ICM, not AKVA.
Engineers didn't like the pulsing idea of AKVA against the nice constant flow of ICM.
Use solenoid as backup if valve fails or power failure with t/stat function (probably more expensive than AKVA).

So sounds either way is OK!

TEAT was a problem on larger screws, as not big enough, had to put a needle valve in parallel to keep up.

I think Frick use ICM as well

Tycho
30-12-2015, 02:44 AM
We hardly do liquid injection at all, but the few I have been involved with, we used ICM, not AKVA.
Engineers didn't like the pulsing idea of AKVA against the nice constant flow of ICM.
Use solenoid as backup if valve fails or power failure with t/stat function (probably more expensive than AKVA).

So sounds either way is OK!

TEAT was a problem on larger screws, as not big enough, had to put a needle valve in parallel to keep up.

I think Frick use ICM as well

As of now we use the AKVA up to the full range of the XRV204, if your engineers don't like it, they might me behind the times :)
I was skeptical in the beginning, but as I see now, the AKVA pulsing keeps the discharge temperature steadier than any TEAT I have ever seen.

We also have a smaller AKVA bypass valve that opens if the Discharge temperature passes 65C, with the TEAT, this valve would be active at full capacity, but after we started using the AKVA I have never seen th ebypass opening.


I can see the ICM working, but it just seems like overkill, why brink an ICM to do the job of an AKVA :)

RANGER1
30-12-2015, 04:11 AM
Because we hardly use liquid injection a call was made to use ICM.
It was thought to be smoother constant flow, instead of on/off pulsing, which may have caused an issue we didn't know about.
I installed ICM on Mycom 250L equivalent to WRV255165 high side compressor.
Not sure if capacity of AKVA could handle it, would have to look.
Anyway we now know it works Ok so would consider it next time.
Do you instal a solenoid upstream of AKVA?

Glenn Moore
01-01-2016, 06:17 PM
Hi Ranger /Tycho
you should never fit a solenoid valve in series with an AKV/A valve. Solenoid valves of that size are mostly of the servo action type and likewise so is the AKV/A valve. As the AKVA valve opens and closes , the solenoid valve would do the same due to the stop and start of the refrigerant flow , this causes a double liquid hammer effect. If you feel the need to fit a solenoid valve in series with the AKVA valve use the EVRAT valve or ICM valve in ON/OFF mode , but as the AKVA is a dual solenoid valve/expansion valve there should be no need to fit a further valve.
Some large screw compressors manufacturers use the TEAT 20-8 valve as a pilot valve for the PMFL or PMFH for liquid injection control when larger capacity is involved.

RANGER1
02-01-2016, 12:49 AM
Glenn thanks,
Can't remember but think we use solenoid upstream of AKVA.
We seem to be belts & braces as one call on some things would pay for belts & braces mentality.
Interestingly we can only buy EVRAT in Australia, initially to reduce warehouse double up stock, so not sure if you can even get a EVRA now or spare parts.
Believe you can still get TEAT, but have to buy in individual parts & put it together yourself.

Magoo
02-01-2016, 01:53 AM
Hi ranger1
I know what you are saying about getting Evra valves let alone any service kits for valves. Totally ridiculous situation. If and when we can get them here they are priced beyond stupidity. Via Australia via Singapore via Europe BUT made in China, just up the road so to speak. Grump!!! Mr Dan and Mr Foss have a lot to answer for. So now use Hansen.

RANGER1
02-01-2016, 10:04 AM
Hi ranger1
I know what you are saying about getting Evra valves let alone any service kits for valves. Totally ridiculous situation. If and when we can get them here they are priced beyond stupidity. Via Australia via Singapore via Europe BUT made in China, just up the road so to speak. Grump!!! Mr Dan and Mr Foss have a lot to answer for. So now use Hansen.

I think there are a number of things we don't even get to see out here.
Years ago a guy from the UK comes out here & has one of those solenoid magnets for testing, commissioning.
We ask about it & now readily available.
I think they are very geared up for USA these days, as imagine it's a massive market to get into.
They even changed all the valve cap colours to suit them.
The older style solenoids will have to be replaced, as cannot get service kits, so expected to get a new valve.
The kits have so much in them, most of it wasted.

Tycho
02-01-2016, 04:17 PM
Because we hardly use liquid injection a call was made to use ICM.
It was thought to be smoother constant flow, instead of on/off pulsing, which may have caused an issue we didn't know about.
I installed ICM on Mycom 250L equivalent to WRV255165 high side compressor.
Not sure if capacity of AKVA could handle it, would have to look.
Anyway we now know it works Ok so would consider it next time.
Do you instal a solenoid upstream of AKVA?

There is a NRV valve upstream, no extra solenoid.
The biggest problem now is with the NRV, it's a danfoss SCA-X, and the company that builds the units for us seems to manage to clip the o-ring on the valve insert of almost all of them :)


They even changed all the valve cap colours to suit them.

So that's why they switched the colors on the SCA and REG valves, I still have to think twice before telling someone what color the valve is :)

RANGER1
02-01-2016, 10:42 PM
Tycho, any chance you are locking liquid betweeN NRV & AKVA when system off?
Also out of interest, why do you need a NRV in liquid injection line?
As Glenn says you could also get some flashing ahead of AKVA valve.

Føroyar
30-01-2016, 10:25 PM
Info from Danfoss on Liquid hammerhttp://www.coolpartners.dk/wp-content/uploads/2012/12/LIQUID-HAMMER-VERSION-2-NOV-2000.pdf

RANGER1
30-01-2016, 11:40 PM
Info from Danfoss on Liquid hammerhttp://www.coolpartners.dk/wp-content/uploads/2012/12/LIQUID-HAMMER-VERSION-2-NOV-2000.pdf


Very good link, thanks

Tycho
02-03-2016, 02:16 AM
Tycho, any chance you are locking liquid betweeN NRV & AKVA when system off?
Also out of interest, why do you need a NRV in liquid injection line?
As Glenn says you could also get some flashing ahead of AKVA valve.

No possibility of locking liquid in between the valves, no AKVA or any solenoid valves from danfoss lock in the opposite flow direction... that is why the NRV is there, to stop back flow before it reaches the AKVA, but you know that

RANGER1
02-03-2016, 02:27 AM
No possibility of locking liquid in between the valves, no AKVA or any solenoid valves from danfoss lock in the opposite flow direction... that is why the NRV is there, to stop back flow before it reaches the AKVA, but you know that

In your earlier post thought it mentioned check valve upstream of AKVA, which would liquid lock.
Mother way adobo problems.

Tycho
04-03-2016, 05:41 PM
----> AKVA----> check valve----> Compressor

:)

RANGER1
04-03-2016, 10:25 PM
----> AKVA----> check valve----> Compressor

:)

Tycho, what brand or type of check valve.
We had a number disintegrate & pieces enter into rotors.
Because of it's constant cycling, opening & closing millions of times.

Glenn Moore may have some input, hopefully you don't get our problem.

Tycho
07-03-2016, 05:13 PM
Tycho, what brand or type of check valve.
We had a number disintegrate & pieces enter into rotors.
Because of it's constant cycling, opening & closing millions of times.

Glenn Moore may have some input, hopefully you don't get our problem.

In my haste I forgot to mention that there is of course a filter between the check valve and the compressor.

The check valve is a danfoss SCA, they are picton check valves so they have some damping and hopefully won't rattle to pieces :)

RANGER1
07-03-2016, 09:11 PM
In my haste I forgot to mention that there is of course a filter between the check valve and the compressor.

The check valve is a danfoss SCA, they are picton check valves so they have some damping and hopefully won't rattle to pieces :)

All good, is there a reason for the check valve on liquid injection line, or is it just for safety.
I have never seen one in that application, economiser need one for sure.