“effective handling of air, water, and oil in ammonia
TRANSCRIPT
Laxmikant Dandawate ( Director – Marketing )Star Coolers & Condensers Pvt LtdEmail : [email protected] No : +91 20 25395550Cell No : +91 9422088939
“Effective Handling of Air, Water, and Oil in Ammonia Refrigeration Systems to Conserve Energy”
Sustainable Management of Refrigeration Technologies in Marine and Off-Shore Fisheries Sectors , 6-8 April 2017 ,
Bangkok
Why bother at all?In our experience:
Air, water and oil are the cause of most problems in refrigeration
systemsSymptoms include:
• Loosing capacity over the years• Capacity problems during the summer• Increased power consumption• Higher service/maintenance costs• Oil decomposing • Unexplained behavior…
Often the symptoms are addressed not the root problem
What happens ?• Air
• Occupy condenser surface -> higher condensing pressure• Blocking drainage of liquid• Chemical reactions, oxidation of oil and metals• Control problems due to air pockets (HP float valves)
• Water• Chemical reactions, breaking down of oil, Corrosion• Shift in saturated vapor pressure• Lubrication problems (especially ball and roller bearings)
• Oil• Heat exchanger and / or evaporator fouling• Cost of oil, filling and draining by authorized personnel, disposal• Risk of ammonia leaks during draining
Consequences on performance
“Rules of thumb”
1°C increase mean approx.:1% lower cooling capacity3% lower COP3.1% higher power consumption
1°C decrease mean approx.:
At Capacity COP Power+10°C -3.6% -5.0% +5.2%
0°C -4.0% -4.3% +4.5%-10°C -4.4% -3.8% +4.0%-20°C -5.1% -3.5% +3.6%-30°C -5.5% -3.9% +4.1%-40°C -6.5% -4.4% +4.6%-50°C -7.3% -5.0% +5.2%
Numbers from average of Sabroe recip and screwPower is with unchanged cooling capacity
Condenser
EvaporatorCompressor
Discharge pressure
Suction pressure
Receiver
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kch
ICE DRAW
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•Drawn into low pressure systems:•Leaking shaft seals, gaskets, valve stems etc. draw in air including moisture
•Service and maintenance, all systems:•”Pure” anhydrous R717 contain 0.3% water•Inappropriate evacuation after opening (vacuum pumps used correctly?)•Residual R717 absorb moisture from air
•Chemical reactions (non-condensibles), all systems:•Ammonia and metals (especially aluminum and zinc)
•Alu gaskets, galvanization, zinc chromating on valves etc.
•Ammonia and oil in the presence of water/air reacts chemically
Conclusion:ALL systems will be contaminated over time no matter the suction pressure is above atmospheric pressure
How do we get air and water in systems?
“I don’t have air in my system”
Symptoms of air in the system?
LP float valve systems
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Condenser
Discharge pipe
Liquid drain:Max 1 to 1.5K subcooling.ALWAYS same temperature.
Receiver
To system
Deviation from this mean air in system and/or wrong piping
Hot top and cold bottom= problems
Pressure equalization
Symptoms of air in the system?
HP float valve systems
CondenserAir cycles in the system:
•No alarming high condensing pressure!•Compressor takes air and recompress it•Decreased cooling capacity•Decreasing COP•Accelerating chemical reactions in compressor oil and LP side of system•Corrosion, sludge and black oil
HP floats always have a bleed hole because of air
Note: Air is heavier than ammonia gas
HP-float valveTo system
Subcooling in condenserDesuperheating
Condensing
Subcooling
Subcooling
Correct function
Air Filled
Flooded
Works
Doesn’t work
80°C
14°C
22°C
18°C
22°C
Example: Condensing temp 22°C, Air wet bulb approx 8°C
Solving problems“Words to live by”
How do we get air out?LP float valve system
Correct piping and an effective air purger
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ICEDRAW.DK
EV L
Air purger type – CPA-10
RT5ART3CONTROL BOX
PurgeON
OFF
Receiver
Condenser
To wet suction
Liquid to evaporators
Discharge pipe
Liquid from
pumps
2 mm slitCollecting air above liquid surface
How do we get air out?HP float valve system
Correct piping and an effective air purger
EV L
Air purger type – CPA-10
RT5ART3
CONTROL BOX
PurgeON
OFF
HP-float valve
Condenser
Liquid to evaporator
Discharge pipe
To wet suction
LiquidFrom
pumps
Purging air, not R717
HBLC
ALAR
MLI
QU
ID
POW
ER
HBLE
E
V
LC
O
N T R O L
R
SCA
AIRVENT(ARMSTRONG)
SVASVA
ORIFICE
FIA
EVM+CVH
EVM+CVH
SVA
INLET – HIGH PRESSURE FOULED GAS (Refrigerant and non-condensable gas)
OIL DRAIN
AIR OUT
WET SUCTION
LIQUID FROM PUMPS
ICEDRAW.DK
AIR PURGER TYPE – CPA-10
RT5A RT3 CONTROL BOX
PurgeON
OFF
1011
12
1
2
34
5
6
7
8
9
14
15
13
Air purger capacity R717 [m3/hr]
0,312
0,314
0,316
0,318
0,32
0,322
0,324
0,326
0,328
0,33
0 10 20 30 40 50 60
Condensing temperature [°C]
Vol
ume
flow
at C
onde
nsin
g pr
essu
re [m
3/hr
]0
1
2
3
4
5
6
7
8
9
10
Vol
ume
flow
at 1
atm
, 20°
C
[m3/
hr]
Flow at Condensing pressure Flow at 1 atm, 20°C
Highest pressure at lowest temperature -> lowest possible R717 content
Consequences – H20 in R717
2% reduction in refrigeration capacity each 1% water
1% more power consumption each 1% water
% Water1%0,5%
Max 1%
•Increased power consumption
•Reduced refrigeration capacity
•Lower evap pressure at the same temperature
•Oil is broken down and creates nitro compounds
•Nitro compounds can dissolve in the NH3 and colour it
•Leaks due to embrittlement of O-rings and gaskets
•Leaks due to galvanic corrosion
•Wear and tear on valves and controls
•Sludge in the system
Note: Water accumulate on the low pressure side
Measuring H20 in R717
Weight % water in ammonia
0%1%2%3%4%5%6%7%8%9%
10%
0 0,5 1 1,5 2 2,5 3
Water remaining in glass
Wat
er w
eigh
t %
W%(50 ml glass) W%(100 ml glass)
Always take sample from Low pressure side of system
Sample from polluted System (H2O and nitro compounds)
H20 content in Oil
Effect on Ball and roller bearings:
Less than 100ppm recommended
300ppm -> half service life
CPW-15 water purger
•Self regulating •No regulation devices•No maintenance•No electrical connections•Easy installation •Energy neutral
Low load High load
“Everything should be made as simple as possible, but not simpler”
Albert Einstein
LP- float valve
Ice
Liquid from receiver
Liquid to subcooledliquid line
To wet suction
Insulation
NozzleLP-liquid frompump
Ice
Liquid from receiver
Liquid to subcooledliquid line
To wet suction
LP- float valve
Nozzle
Insulation
LP-liquid frompump
Oil management
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kch kch
Receiver
Compressor Compressor
Condenser
Oilfreehot gas
for defrosting
Motorvalve
Liquid to evaporators
Pressure equalization
(Closed when defrosting)
HBSO1
ICE DRAW ICE DRAW
HBSO1
CPO
120ppm 120ppm
35ppm
35ppm
>1ppm oil
Note !High TC (heat pump) :De-gassing vessel necessary
CPO – HP oil separation unitOil separation in liquid R717
HP liquid containing oil
CPO variants/options:•Stand alone•Combined with receiver•With oil cooler liquid priority•Defrost hot gas supply
< 1 ppm oil
Advantages: •Oil stays on HP side, no pollution or breakdown•Very simple oil return system•Maintenance free oil management•No oil consumptionDisadvantage:•Increased refrigerant charge
Dry clean oil to compressors
Proof of concept:178 liters separated in 9 months.17 liters found on LP side due to hotgas defrost
HB- oil switches
Oil-freehot gas
for defrostingCPO
Separation: Require knowledge about oil not commonly available
Tomorrows problem-free R717 system
ICE DRAW by Kurt C. Hilbrecht
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Evaporative condenser
NH3 pump NH3 pump
To open air
Oil-free hot gas line
Equalization line
Liquid line
Liquid line (sub cooled)
LLG
Pump separator
ReceiverSystem cleaner- CPW Air purger
- CPA
Oil collector
Purge line
HBSR
Economizer
MVS 661
HBLC
ICE-SCREW Mk 1
ICE-MATIC
MVS 661
MVS 661
Shell and Tube Chiller
Screw compressor
Reciprocatingcompressor
HBSR
CONTROL BOX
Purge ON
OFF
O
LE
EV
L O
HBLC
HBSR
HBSR
HBLC
HBSR
HBSR
HBLT-A1 HBLT-C1
HBSO1
HBSO1
HBOC
HBSR
HBSR
HBSR
To open air
To open air
HBCP
HBLT-A1
HBLT-C1
To open air
Control box
Make-upwater
system
Receiver
REG
Air cooler – pump system
Plate freezer- pump system
REG
ICEDRAW.DK
HBSO1
kch
CONTROLSYSTEM
ICE-MATIC
ICE DRAW
HBOC
ICE DRAWHBCP-X
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Flake ice machine
kch
REG
CPO
HBSR
