Thermosysphin Help - Surging Liquid

Hello All.
I am new here and not sure if this is where i need to post this but here goes.

I have a 10 Ton Flooded evap thermosyphin chiller with a hasagawa compressor.

The surge drum is over filling and shutting down the chiller on high level. I shut off the liquid line to the Ha Phillips float valve and tried to pump down the system. The level in the surge drum kept rising and fallling even though the liquid source had been valved off.

Why would the level fluxuate that much when no liquid was entering?

What would cause the level to rise too high? I took apart the float valve assembly and cleaned all the parts then reinstalled it and it seems to help.

I have attatched pics to see the level indicators.
You can actually see DIFFERENT levels in each glass when this problem occurs. There is distinctly levels inside the glass ports. WEIRD

any opinions or help would be greatly appreciatied

Clay

I can email better pics if anyone needs.

Quote:

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Originally Posted by Iamclayman2000

The level in the surge drum kept rising and fallling even though the liquid source had been valved off.

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Is the compressor loading and unloading when this occurs?

Hi,
excuse me please I don't know much English, but when close supply to the tank and Shall I on compressor lading, surface begins storm, accrues it as when soars, but stop down. I trust as though do you understand my thought.

nh3wizard - Is the float the only thing controlling th level? If just operating on the float I would suggest checking the head and see if it is opening and closing the valve, if its not, replace the head.
The float is the only thing controlling liquid but there is a hot gas valve for low load.
The valve is a HA PHILLIPS valve. I ordered a new one and replaced it this morning.

Were you able to pump it down? Your feed valve might not be closing all of the way, and thats why you keep getting shut down on high level.
I was not able to pump it down. When i tried i filled the reciever 100%. But during the pumpdown period the surge drum was still surging but with no liquid entering.

Are your pressures remaining steady? When does this happen? During start-up or does it happen when its been running for a while?
Cant tell on pressures, the chiller does not stay online long enough. It happend after 11days straight running at -30F setpoint with no load besides Hot Gas.

I've jumped around a bit but hopefully you'll understand.

US Iceman - Is the compressor loading and unloading when this occurs?
The compressor is running unloaded while being pumped down and surging.

josef - Hi,
excuse me please I don't know much English, but when close supply to the tank and Shall I on compressor lading, surface begins storm, accrues it as when soars, but stop down. I trust as though do you understand my thought.
I do apologize but i dont understand your thought.

Hi Iamclayman 2000,
when will close cooler, liquid cooler returns to the separator and surface soars, how double take piping you have you got?, what dimension?, cooler NH3?

double take piping?

it is R507 refrigerant

is there a better way to control the level in the surge drum.

clay

it just shut down again on high level.

grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr

i dont know what eles to do.

clay

Oh, at our place use on bigger achievements ammonia. As large R 502 system I don't know, I'm sorry you, I can't assist in. :mad:

Hello Clay,
What type of evaporator do you have on bottom of surge drum? Is it a shell and tube or something else as cant tell from pictures.I was thinking on two lines,one is product you are cooling have a good flow rate (bye the way what is it )?
or or is it freezing up on tubes causing poor heat transfer.Also on fridge side is evaporator logged with oil or a valve say in wet return line not opening properly.
I had ajob recently where a air cooler with a surge drum on ammonia would not pump down at all from a high level because air cooler was oil logged .The surge drum was iced up on level control column etc,
but due to no circulation of refrigerant no cooling or heat transfer took place so level would not lower in vessel.This unit had a leaking liquid line solonoid as well but isolating valve was ok.
Your hot gas low load valve could also have been leaking not helping matters.
Other questions
if the level is ok is commressor loading up and how fast?
has this system been operating ok in the past and is this a new problem ?
has any recent work been carried out which could have some link to your problems
has compressor had any oil carry over or oil return issues?
has product temps been gradually deteriorating?

Quote:

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Originally Posted by me

Is the compressor loading and unloading when this occurs?

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Quote:

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Originally Posted by Iamclayman2000

The compressor is running unloaded while being pumped down and surging.

reply to nh3wizard:
But during the pumpdown period the surge drum was still surging but with no liquid entering.

....but there is a hot gas valve for low load.

It happened after 11 days straight running at -30F setpoint with no load besides Hot Gas.

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Check the hot gas bypass valve to make sure it is controlling properly. If the valve was selected properly the hot gas valve should start to open when the compressor is at the minimum step of capacity control. At that point, the hot gas valve should modulate to control suction pressure.

The surging liquid could be caused by the hot gas valve opening and closing (blowing hot gas into the liquid) or the compressor is loading and unloading causing the liquid to boil violently.

Iamclayman2000 did you ever figure out your problem?

Sorry it has been crazy here.
I have not solved my problem, infact it has gotten worse. The only way to get the system to stay on line is to pump it down and let it run again.

RANGER1

Hello Clay,
What type of evaporator do you have on bottom of surge drum? Is it a shell and tube or something else as cant tell from pictures.
It is a shell and tube with oil return lines draining the bottom of the evap, surge drum, and sight glass piping back to the oil reciever via a venturi.
I was thinking on two lines,one is product you are cooling have a good flow rate (bye the way what is it )? Flow rate is good, 50gpm.
or or is it freezing up on tubes causing poor heat transfer.Also on fridge side is evaporator logged with oil or a valve say in wet return line not opening properly. Return lines are working, they have sight glasses in them and you can see the flow.
I had ajob recently where a air cooler with a surge drum on ammonia would not pump down at all from a high level because air cooler was oil logged .The surge drum was iced up on level control column etc,
but due to no circulation of refrigerant no cooling or heat transfer took place so level would not lower in vessel.This unit had a leaking liquid line solonoid as well but isolating valve was ok.
Your hot gas low load valve could also have been leaking not helping matters.
Other questions
if the level is ok is commressor loading up and how fast? Level is ok and compressor is loading like normal. it doesnt matter which stage it is in.
has this system been operating ok in the past and is this a new problem ? been an ongoing problem but it is usually solved for a few months by changing or cleaning the HAPhillips float valve cartrige
has any recent work been carried out which could have some link to your problems no work done on it.
has compressor had any oil carry over or oil return issues? no oil problems, oil in the reciever and in the sump.
has product temps been gradually deteriorating? no problem with process temp except when the system goes down
.
US Iceman

Check the hot gas bypass valve to make sure it is controlling properly. If the valve was selected properly the hot gas valve should start to open when the compressor is at the minimum step of capacity control. At that point, the hot gas valve should modulate to control suction pressure.
after pumping down the system last thursday i left the hot gas valve off by accident but the system still shut down on high surge tank level a few times over the weekend.
The surging liquid could be caused by the hot gas valve opening and closing (blowing hot gas into the liquid) or the compressor is loading and unloading causing the liquid to boil violently.

What i dont understand is that the surge tank was STILL surging while i was pumping down. the level was going up and down in the sight glasses like normal (as if liquid was being fed in via float vavle(but it was valved off)).
What could cause the surging???
it was like a violent storm in the tank.

What effect could AIR or NON CONDENSABLES have on the system?
The system is in a vacume when down to setpoint and very well could have leaks.

Thanks
Sorry for the delay.
Clay

Quote:

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Originally Posted by Iamclayman2000

The surging liquid could be caused by the hot gas valve opening and closing (blowing hot gas into the liquid) or the compressor is loading and unloading causing the liquid to boil violently.

What i don't understand is that the surge tank was STILL surging while i was pumping down. the level was going up and down in the sight glasses like normal (as if liquid was being fed in via float valve(but it was valved off)).
What could cause the surging???
it was like a violent storm in the tank.

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When you say pumping down; did you only have the liquid supply closed? If the hot gas bypass valve is still active and open to the discharge line the flow of high pressure refrigerant into the surge drum could occur.

As the suction pressure decreases, the hot gas regulator should begin to open. This is the purpose of the hot gas bypass; to maintain constant suction pressure and false load the compressor.

If you are pumping down the system, the hot gas valve can admit high pressure refrigerant into the surge drum which can cause violent boiling (especially if the hot gas connection is under the liquid level in the surge drum).

And also...

Depending on where the liquid level is in the surge drum in relation to the float switch this could be part of the problem also. When the system is off, the liquid level in the vessel is calm. However, when the compressor starts up the suction pressure is reduced which begins to boil the refrigerant. If the suction pressure is pulled down too fast the liquid level in the vessel can rise or appear to be very chaotic inside.

How cold are you actually trying to maintain? A vacuum on R-507 starts at about -52°F evaporating temperature. That is pretty darn cold for liquids!

Iceman - I would close the liquid line service valve and the hot gas service valve to prevent any refrigerant to enter the vessle.
While pumping down the liquid is very chaotic, and there is nothing entering the vessle.
What do you mean about the relation of the float switch and the liquid level? the float swich is aprox 10" above the float level control.
While pumping down the pressure would stay around 5psi.
Process temp setpoint is -40deg.
Process fluid is a citris based antifreeze, delimonene

Do you do long distance service calls iceman?

Clay

Hi, Iamclayman2000 :)

Quote:

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Originally Posted by Iamclayman2000

Iceman - I would close the liquid line service valve and the hot gas service valve to prevent any refrigerant to enter the vessle.
While pumping down the liquid is very chaotic, and there is nothing entering the vessle.
What do you mean about the relation of the float switch and the liquid level? the float swich is aprox 10" above the float level control.
While pumping down the pressure would stay around 5psi.
Process temp setpoint is -40deg.
Process fluid is a citris based antifreeze, delimonene

Do you do long distance service calls iceman?

Clay

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with US Iceman you are in good hands.... long distance service calls ... why not but he will decide about....

....regarding level switch and level float ... maybe you can rise level switch for a little 50mm/2inches to avoid high level alarm.... check your documentation about changing of levels by moving level switch up or down on pipe....

.... regarding hot gas valve .... I am not sure but I think it is installed for this

Quote:

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Originally Posted by US Iceman

As the suction pressure decreases, the hot gas regulator should begin to open. This is the purpose of the hot gas bypass; to maintain constant suction pressure and false load the compressor.

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and for protection ... in case of low evaporating temperature it is possible to freeze citris based antifreeze, delimonene and damage your chiller .... maybe is not bad idea to control a flow and temperature of delimonene ..... we use a similar hot gas protection in cooler for direct cooling of young beer:)


Best regards, Josip :)

Could there be too much refrigerant in the system?

As long as you have flow through the chiller, the liquid inside will be surging/boiling quite heavlily, even if there is no new refrigerant introduced to the chiller.

the best time to read the liquid level is the instant you stop the compressor, for a second or two, the liquid will settle before starting to boil again until the circulation of coolant is stopped and the temperature of the refrigerant and coolant is equalized.


I would check the refrigerant level. on most flooded chillers, depending on the level control it should be 75% of the shell.

if the shell and tubes are 100% flooded, it will surge/boil to high heavens

Quote:

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Originally Posted by Iamclayman2000

What do you mean about the relation of the float switch and the liquid level? the float switch is aprox 10" above the float level control.

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What happens during a pump down or increase in capacity is the suction pressure decreases. This causes the liquid to boil. In some cases it is possible for the boiling refrigerant to cause the float switch to trip off and then shut down the compressor.

Part of the problem may also be where the return line from chiller dumps into the vessel, which agitates the liquid to make it look like it is surging.

Has this been occurring every since you have had this packaged system?

Yes, I could travel out to your facility and help you to discover the problem. If any corrections are required your normal refrigeration contractor or yourself would have to do the repairs needed. I'm strictly a consultant (although I do know how to pull wrenches when I have to:)).

If you want to, send me a private message and we can exchange emails to discuss.

Ok I may be stupid here but how do you do a private message. I dont see it anyware to send one.

The skid is approx 12yrs old and has been modified several times since it was installed.
It has not happended since the beginning but it has happened many times this year.

And we are the refrigeration/ac contractor on site for the owner. There is a refrigeration contractor that is responsible for the equipment if we cant figure it out but they are out of Houston TX. They have been contacted but have not responded yet.

Clay

Clay,

Hold your cursour over my pen name next to the picture of the rotors. Left click on my name and a small menu should appear. One of the options is to send a private message. Left click on that and compose the meesage. When done, click the submit button ( or send button, I don't remember the exact name).

Tried that and it doesnt show the compose message thing.
I may be too new to have that capability.



Clay

I have decided to remove the charge and leak check.

We found 15 leaks in the system.

We are in process of fixing.

Anyone heard of a restricter tee for the oil skimmer line that uses hot gas to suck it out of the surge drum and evaporator.
I cant find it anyware.

Clay

I think you are refering to a Eductor. FES tried them on screw compressors to remove oil from the seperator as I recall. Google Eductor and you will find explanations of how they work in non-refrigeration applications.

NH3LVR is right; it's probably an eductor.

Standard equipment on Dunham/Bush screw flooded chillers and low-temperature direct expansion chillers as well. All are 3/8" steel tubing, valves and fittings. The D/B system is supplied with hot gas from the downstream side of the oil separator and has a manual valve before the eductor. The eductor suction (the "bull" of the tee) is piped to either a single or multiple valves on the chiller, and there is a sight glass and check valve in this suction line. The discharge of the eductor is piped to the compressor suction downstream of the suction check valve. In operation, the system scavanges "oil rich refrigerant" from the chiller and dumps it into the compressor suction.

IF the check valve in the eductor suction line were to fail open, and IF the eductor is over-fed with hot gas (we throttled the manual valve before the eductor to "no more open than necessary"), it was POSSIBLE to push hot gas into the chiller. I can't honestly say that I ever saw it happen since too many things would have to go wrong first. Still, it was a possibility discussed amongst the service troops.

Does this sound like your system? Is the tube from the eductor suction to the chiller warm during operation? It shouldn't be.

Hi, cmorris69 :)

Quote:

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Originally Posted by cmorris69

NH3LVR is right; it's probably an eductor.

Standard equipment on Dunham/Bush screw flooded chillers and low-temperature direct expansion chillers as well. All are 3/8" steel tubing, valves and fittings. The D/B system is supplied with hot gas from the downstream side of the oil separator and has a manual valve before the eductor. The eductor suction (the "bull" of the tee) is piped to either a single or multiple valves on the chiller, and there is a sight glass and check valve in this suction line. The discharge of the eductor is piped to the compressor suction downstream of the suction check valve. In operation, the system scavanges "oil rich refrigerant" from the chiller and dumps it into the compressor suction.

IF the check valve in the eductor suction line were to fail open, and IF the eductor is over-fed with hot gas (we throttled the manual valve before the eductor to "no more open than necessary"), it was POSSIBLE to push hot gas into the chiller. I can't honestly say that I ever saw it happen since too many things would have to go wrong first. Still, it was a possibility discussed amongst the service troops.

Does this sound like your system? Is the tube from the eductor suction to the chiller warm during operation? It shouldn't be.

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... nice explanation, but maybe to upload some small scheme where we can see it;)

Best regards, Josip :)

Quote:

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Originally Posted by Josip

Hi, cmorris69 :)



... nice explanation, but maybe to upload some small scheme where we can see it;)

Best regards, Josip :)

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Here goes nothing!

Hi iamclayman2000, just returned from holiday and looked what was happening with your post.Maybe you could try restricting top stop valve on control column to say one turn or so to see what happens to surging .if commpressor suction line is to close to control column inside vessel it can be dragged up control level giving false levels in control column.Also what is big parker valve on bottom right hand side of your first picture ?

Hello Clay,

What is the internal volume of the evaporator?

Jean

Quote:

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Originally Posted by Iamclayman2000

Hello All.
I am new here and not sure if this is where i need to post this but here goes.

I have a 10 Ton Flooded evap thermosyphin chiller with a hasagawa compressor.

The surge drum is over filling and shutting down the chiller on high level. I shut off the liquid line to the Ha Phillips float valve and tried to pump down the system. The level in the surge drum kept rising and fallling even though the liquid source had been valved off.

Why would the level fluxuate that much when no liquid was entering?

What would cause the level to rise too high? I took apart the float valve assembly and cleaned all the parts then reinstalled it and it seems to help.

I have attatched pics to see the level indicators.
You can actually see DIFFERENT levels in each glass when this problem occurs. There is distinctly levels inside the glass ports. WEIRD

any opinions or help would be greatly appreciatied

Clay

I can email better pics if anyone needs.

---

Sorry for the long absence.
Been busy fixing this hunk of junk.

Thanks for the tip on the Eductor, i think that is what it is but much smaller.

We ended up having a bad FES processor and replaced it but are still having problems keeping it running because the program was not saved before replacing it and the EPROMM was destroyed in the old one. OHWELL.

We were finally able to restart the chiller last week and got it to run.
Everything was all hunky dory until this morning. I was called in at 1am for a service call on the machine. It ended up blowing a line and dumping the whole charge into the atmosphere. Time to start from scrach again.
Good news is that the surging went away.
My guess was that it was the 9 or so leaks on the low side in a vacumme and sucking in all the air.
Well after i get the new charge back in and run for a while i will update again.

Clay

Shock suction pressures changes will change levels violently in any system with a surge drum, slow load rate of compressor. And sleep at night. After you get all leak stuff sorted, the initial problem is likely to stem from dud controller eprom /PLC.
magoo
magoo