Original message
| exbt2
 |  "Surge Problems on 19XRV Carrier"
, posted Wed 31 Aug 14:05  
We have 2 500 ton evergreen carrier chillers. They both have surge problems. Our #2 chiller is our problem child. It cuts off due to excessive surges. The float valve chamber sweats and the top of the condenser is hot. We have approximently 1500-3000 gpm capability of condenser water available. I have been told unofficially its a float valve problem, is this possible? The chiller had surge problems before they installed it in our plant and they took 200# of 970# out to help with the surge problems. Has anyone heard of this particular problem? Can anyone shed any light?
Harry
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Replies:
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| can
| "Re(1):Surge Problems on 19XRV Carrier" , posted Thu 29 Sep 01:42:
I'm repairing the Carrier centrifugal chiller over 18 years. I hope that I can help you to fix your problem. Would you like to email me a log sheet of these chillers, all the configuration in the service mode of your PIC 2 control system and all settings of your chiller and the VFD settings to me? I also need to know the complete model, serial number, design volt, Hz, Rated Load Amps, design water temp. flow rate, delta P for the condensiong water and chiller water. If you trust me you can try to get the above information. My English is not very well. But hope that can help you. My email address is southeng@biznetvigator.com
Can
Thank you & best regards!
Can
Thank you & best regards!
[this message was edited by can on Thu 29 Sep 02:00] |
| chiller guy
| "Re(1):Surge Problems on 19XRV Carrier" , posted Mon 5 Sep 19:33
Since I do not know your experience level please bear with me if I get too basic. Most common surge problems are low cond water flow, non condensibles(air)in the machine, fouled cond tubes. Also a low refrig charge, or hot tower water will give you fits.Did the situation improve when refrigerant was removed? Who removed it (Carrier rep)? You have plenty of tower water but are you using it?
First thing I suggest is to run an operating log on the unit. Then start analyzing what the unit is doing. What are the approaches, flows, temp drop thru evap vs temp rise thru cond. The unit is designed to shut down in a prolonged surge condition as it could destroy the chiller if left uncorrected
Does this unit have a freq drive.
All refrigerants are safe - All refrigerant are dangerous. The difference is YOU !!!
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| | exbt2
| "Re(2):Surge Problems on 19XRV Carrier" , posted Tue 6 Sep 04:23
Thank you for your response. My chiller experance is limited but I seem to be gaining knowlege every day from people like you in the know. The condenser flow is above design flow with a delta P of 8 or greater. The chiller tubes, both evap side and condenser side were cleaned last winter and we maintain good water chemistry in our loop. We normally run both our cooling towers to keep everything circulating and also keep water flowing through the lag chiller as per suggestion of a carrier tech. Even when we have the other chiller on the condenser loop the delta P is above design. We take daily logs and have been watching them like a hawk. Friday the carrier tech was here and much to our amazement BOTH chillers, when we started them up did NOT have any heat exchange. 2 deg diffrence on evap side and condenser side for a while till we shut them down. Before shutting them down we checked the flow through both heat exchangers and they were both fine, above the desighn delta P. Then they both started working! we were both amazed, especially the tech. My problem is this. We are being told by a carrier engineer that the problem is one as you stated, a condenser flow problem, but we have eliminated that. The tech's (more then one) are saying its very possible its a float valve problem. I could almost see that as causing the no heat exchange problem because there is no flow of referigent.(just a guess). We do have a VFD and have had alarms of low vfd speed, vfd over 10%, those kinds of alarms. The tower water seems to be at 82 degrees in the daytime,(we are in Florida) but there is almost always a 10 degree delta P.
Thanx,
Harry
Harry
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| | All Good Man
| "Re(3):Surge Problems on 19XRV Carrier" , posted Sat 6 Oct 15:45
Did you solve your operating problem?
The float valve is easy to inspect and should be if not already checked.
What was the position of the Inlet Guide Vanes (IGV's)when the unit surged? Is a Split Ring Difuser used on your model?
85 degree inlet water temperature is on the high side but the unit controls should be able to handle it knowing your geographic location.
EWM
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| | gsxrsquid
| "Re(3):Surge Problems on 19XRV Carrier" , posted Fri 28 Apr 16:02
When they cleaned the tubes did they mess with the balance valves in the condenser water circuit. If the valves were opened all the way the flow could be too fast to get a good heat exchange.
It has been awhile since I ran chillers but My experiences with surging was air in the chller, or condenser water problems of one sort or another,, flow/exchange/temp.
I dont know how your towers are sized in relation to chillers. Sometimes that is a problem as well.
90% of being smart is knowing what you are dumb at
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| | chiller guy
| "Re(3):Surge Problems on 19XRV Carrier" , posted Tue 6 Sep 19:57
One thing I find interesting is the same problem with both chillers. Look for a common denominator that could be affecting both. Two things you mentioned caught my attention:
1. Higher than design delta P. I am assuming water flow
2. VFD on the units.
Just like any other refrigeration system you must maintain a minimum differential between cond and evp pressures (think of a TXV).If the pressure gap narrows too much the refrigerant will not flow between the exchangers properly and will act like it is short of gas. This can create a surge like condition.
Now add to this a FREQ drive that is moving little refrigerant as it unloads and the problem is compounded. Then throw in an excessive amount of condenser water that carries away what little heat you have(there goes the head pressure).
Are you seeing this surge during low load conditions or full load? Try getting the flows back to design until you get a handle here.
Clean tubes last winter(or last week)don't mean squat. You can foul those tubes in a week or less. The cond approach compared to the cond pressure and tower water in and out will tell you if you have any fouling. It only takes about .0025" of insulation( fouling) to screw up your heat transfer.
All refrigerants are safe - All refrigerant are dangerous. The difference is YOU !!!
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