So question is where did you measured amperage, since 100A or 90A will trip compressor safety devices?
Amperage should be checked at compressor power conections.
Printable View
The system was charged 3 and half years ago when I was in another plant. From previous commissioning data temp. Difference through HE always 1-2 C.
Amperage measured at compressor power connections.
& compressor did not trip for high amp. even its amp. reached 103 amp.
One of our engineer checked and replay us it will trip after a certain period of time. Only the chiller tripped for freezing fault for several times. Whenever HE inlet ref. temp. reached at 3 deg. C.
This caught my eye.
The thought occurred to me that if the water were to have frozen & deformed the inside of the PHE - without rupturing the plates - that perhaps the water is simply bypassing the rest of the evap?
What are the real refrigerant-side pressure drops like in the evap, I wonder? I'll go back through your measurements again, before I comment further.
@Bashir,
I'm looking to see what you have mentioned about your air-cooled condenser. To me, the air is heating up a lot, considering that the evap is hardly operating.
What is happening to the condenser fan? What is the air velocity entering the condenser face? I'd expect it to be in the range ~ 1.8 - 3.6 m/s. What have you got?
Are there any head-pressure control valves, or hot-gas bypass circuits in this system?
I have to also wonder if someone has not perhaps worked on the system & topped up with the incorrect gas, or oil? Something weird seems to be going on.
Perhaps it would be an idea to reclaim the refrigerant, drain the oil, flush the system, replace filter-drier/s, clean/check TXV orifice, add new oil charge, pressure test with N2, purge with N2/vacuum x3, add fresh refrigerant to manufacturer's recommendations? I'm concerned that something may has occurred in the system that is not obvious from the data we are seeing. At least then you will have a firm base to work from.
No Head-pressure control valves or hot-gas bypass circuits in this system, or filter-drier(all inside the compressor).
Ok, I am clearing you, its a three and half years old system, as per our maintenance history book we never topped up the system only we clean the evaporator for six time (in last one year), and clean the condenser fin as outside environment is quite dirty.
And recently we changed the chiller position and find not sufficient or no cooling, and then we charge/topped up the system (we charge slowly as by weight & also monitor comp. amp).
One thing is common that previously chiller was tripped due to frizzing fault and still that problem present, we check all the thermocouples (chilled water in/out, freeze protection), find no problem.
We are already asked for spare parts to the supplier, but if the problem present inside HE then what happen if we change EEV, charge the system properly, still system will act as present. I think management will not forgot or forgive us!
I agree recover charge and oil and start fresh. Any way to measure pressure drop accross evap? Check agains design op.
If your HE has Δt of 0K or 1K as measured and stated in your data than freezing fault mean that your set point is set to low or you have some changes in water flow during operation that can lead to high Δt. Or you have faulty temperature sensors.
Also, alarm of 3°C should be triggered by water outlet temperature.
According to our previous discussion I think that main problem there is incorrect water flow which probably varies as other circuits on that network closes or opens for regulation and by that action changes balance of flows. That can be connected with reading of evaporation temperature at 9:10, 10:30, 11:30. So you should first ensure steady and corect water flow at that chiller. Where did you measuring water outlet temperature. Is that measured at common pipe of other chillers, or at evaporator outlet?
Next what can be read from your data is that you still have lack of any subcooling. Ether it is short of refrigerant, incorrect or contaminated refrigerant or your air flow is incorrect or your heat exchanger need cleaning.
So you should measure airflow, clean condenser and recover portion of refrigerant in drum and check its correct PT ratio.
Also, according to your data, you have negative approach at condenser in amount which is possible only when there is no saturated refrigerant there.
If there is no liquid refrigerant at enter of EEV than there is no liquid refrigerant that evaporate and that is why other data looks like that in your table.
No subcooling at condenser outlet
No subcooling at EEV inlet
Low amperage
High evaporator approach
Negative condenser approach (no saturation)
everybody confirm that PHE is in trouble.so better to overhaul or replace PHE.please go to this link.you can down load PHE maintenance manual
http://www.schaufcompany.com/v3/owner/alfalaval.html:)moideen-dubai
Sir,
Thanks, we will do what you suggest.
We measured chilled water temperature just after the HE, actually we provide two temperature gauges in the chilled water inlet & outlet, and we calibrate it several times with the testo apparatus. And we can check it through inlet outlet sensors.
Thanks Sir,
@moideen
It will help us lot.
Thanking You,
Bashir
It explained that the density of subcooling on refrigeration for correctly making the expansion valve is necessary saturation temperature of 15 degrees Fahrenheit above the temperature cycle is good.
Better characteristics for proper charging system is suctionsuperheat saturation temperature above 10 degrees Fahrenheit is good.If this rate is higher undercharge system. If this amount was less overcharge system</SPAN>
Have you checked that the evaporator is clean and clear on the water wide, in many places even supposedly clean water can leave scale which creates a restriction in the water lines and insulation from the refrigerant both of which will stop your water from chilling.
Sir,
After cleaning the HE, and adjusting the chilled water inlet and outlet flow we are getting improved result (I mentioned improve result only the basis of chilled water inlet and outlet temp. diff. previously it was 1 or 0 but now it consistently 2 or 3). We close 70% chilled water inlet line & 10% chilled water outlet line (valves r butterfly). What is the logic? If i want to set up a logic. We yet not charged the system as refrigerant is not available, it will take some time.
Motor running amperes are dependent on mechanical state of compressor and compression ratio. With corect charge and various temperatures of evaporation and condensation (which depends on many things) you have various current reading. Therefore, current of compressor is not clear indication of correct charge, but it should be monitored in case if something other is wrong, or to be sure that you are not grossly overcharged.
Sight glass could be misleading especially with blends because they represent difference in flow resistance (therefore pressure change) and liquid refrigerant could flash in sight glass and collapse again after sight glass when flow restriction become same as before sight glass.
Proper subcooling and proper superheat along with proper air/water flows and cleanliness of heat exchangers will tell you that you have balanced and properly charged system.
how has this story ended??? ore is the problem still on??
Ice
Hello
This is Gareth Jones
what type of evaporator is it? Plate heat exchanger or shell and tube?
It would appear that there is a lack of heat exchange occuring, if it is a shell and tube it is possible that the refrigerant is bypassing the evaporator via. a split end gasket, allowing low pressure liquid refrigerant through to the suction. I have had a similar problem in the past but my concern was with the low superheat. The compressor turned out to have the wrong oil, mineral instead of synthetic. This caused waxing on the evaporator tubes which reduced the heat exchange and superheat.
Gareth
CNM ONLINE
sometnhing may happen with the page, I can not replay
@ICE: This is really frustrating for all of us, our knowledge is limited but we tried all the possible ways. It seems that the problem with the beginning or commissioning period nearly two & half years ago (and that time I worked in another Cement plant), we did not have the commissioning report, and if we analysis last one and half year’s operation log sheet we found some interesting observation:
We open the LC for some spare parts and offer help from local HITACHI supplier, hoping that they will fill & understand what they have done with the system two years ago!
Maybe I am wrong in my thinking that flash gas and liquid refrigerant mixture at exit of EXV is not in saturated state. Maybe someone could clear that for both of us.
Here is some thread with that thematic:
http://www.refrigeration-engineer.co...read.php?t=888
Spare evaporator perhaps?
spare complete unit (LOL)
Ice
I am sure that are so many China made chillers of better quality than Hitachi.:rolleyes:
check if you dont mixed two kind of oil
I am sure that are so many China made chillers of better quality than Hitachi.:rolleyes:
Sir,
They provide us lots of papers and ask for data, now we are waiting, waiting, & waiting..............
@dgt: We did nothing with the compressor ever
Hi..
I am new to the site and this is my first post. Not sure what the update is at present ... the post being close to two months now.
I have followed with interest your discussion above and I am curious to know the outcome ... and what made you believe there was a problem in the first place. You mentioned no cooling ... what was the temperature of the medium being cooled ?
What made you believe there was a problem with the chiller ?
Regards