Transcript OPG WTP Performance / Trends in High Purity Water Treatment

OPG WTP Performance / Trends in High
Purity Water Treatment
Presented at IAPWS Workshop
May 11, 2009
By
Gabriel Nicolaides
Outline
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Darlington WTP - Background
Pickering WTP - Background
Demin Water Quality: DND vs. PND
Demin Water Quality Survey
Trends in High Purity Water Treatment
New WTP Design Considerations
RO for Primary Demineralization
UF for Pretreatment
Different Options for Polishing Deionization
Darlington WTP - Background
 WTP design finalized in 1985, WTP in service 1986
 Fourth in a series of WTPs designed by “old” Ontario
Hydro: 1. PNGS, 2. BNGS-A, 3. BNGS-B, 4. DNGS
 “conventional” WTP design consisting of clarification /
sand filtration / activated carbon / ion exchange
 Key features incorporated into the design of the WTP:
• Deep water intake 1 km off-shore, 10 m below the water surface
• Dual clarifiers
• External regeneration of mixed beds
Darlington WTP Process
Pickering WTP - Background
• OPG’s 1st outsourced WTP
• 10 year operating contract awarded to
Nalco in Feb. 2001; a local company, EcoTec, supplied the equipment and assists
with WTP operation and key maintenance
activities
• WTP in-service since Oct. 2001
Site Selection/Raw Water Source
• WTP located outside of protected area;
allows vendor ready access and permits
equipment retrofits as commercial
modifications
• CCWR outfall structure used for raw water
supply pumps, warm raw water for
improved RO efficiency and reduced footprint
Pickering WTP – External View
OPG owns the building housing the WTP;
Nalco owns and operates the equipment
PND WTP Process
Pickering WTP – Internal View
Demin Water Quality: DND vs. PND
WTP Demineralized Water Quality at PND and DND vs. OPG Specifications and WANO Guidelines
Parameters
Temperature
Resistivity at 25 ºC
Calculated Conductivity at 25 ºC
Sodium
Reactive Silica
Total Organic Carbon (TOC)
Units
( ºC)
Mohm-cm
mS/m
µg/kg
µg/kg
µg/kg
Pickering WTP
(Mean: 2004 - 2006)
20.6
18.28
0.0055
0.074
0.33
6.1
Darlington WTP1
Darlington WTP2
(2003 Quality Data) (Mean: 2006 - 2007)
NA
NA
17.2
0.0058
0.14
2.33
125
16.9
0.0059
0.08
5.38
NA
"NA" - Not Available;
"NS" - Not Specified
1 Darlington WTP Plant Performance Review, Report No. N-REP-74000-10000 R00, 2003
2 Darlington WTP Plant Performance & Operating Cost Review, Report No. N-REP-74000-10003 R00, July 2008
3 OPG Chemistry Specifications, N-STH-01807-10000, Section B16, Rev. 00, June 19, 2003
4 Guidelines for Chemistry at Nuclear Power Stations, WANO GL 2001-08, August 2002
Demin Water Chemistry Control Limits
WANO Achievable PWR
Pickering
NA
OPG / Darlington3
NA
Make-up Water Guidelines4
NA
> 16.7
< 0.006
< 0.2
< 2.0
< 10.0
> 12.5
≤ 0.008
≤ 1.0
≤ 10
NS
> 12.5
< 0.008
< 1.0
< 10
< 20
Demin Water Quality Survey
• DND WTP was ranked against 24 other
Nuclear Stations. DND WTP ranked 10th
out of 25 stations, placing it in the 2nd
quartile
• PND WTP ranked 6th out of the 25
stations, placing it in the 1st quartile
Trends in High Purity Water Treatment
• Outsourcing of WTP Operation
• Extensive Use of Membrane-Based
Technologies (e.g. UF, RO)
• Improved demin water quality especially
lower Na & TOC levels
• Reduction / elimination of hazardous
chemicals (acid, caustic)
• Automatic operation / remote monitoring
reduces labour cost
New WTP Design Considerations
• What are you starting with? - Feed water Quality
& Characteristics
– Source – surface water, well water, other
– Seasonal Variations & Effects
– Dissolved & Suspended Solids
• What quality do you need? - Finished water
Quality & Characteristics
– Benchmark Chemistry
– Dissolved Solids (TDS, specific ions, etc.)
– TOC
“Heart” of the Water Treatment System is RO
UF
RO
EDI
or
IX polishing
RO Membrane Feed Specs
• RO feedwater requirements are:
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SDI:
Chlorine (free):
Iron:
Turbidity:
< 3.0
< 0.01 ppm
< 0.1 ppm
< 0.2 NTU
Filtration Spectrum
Hollow-fibre Ultrafiltration
Permeate to Treated
Water Storage
Permeate/
Bakcpulse
Pump
Inlet Water
Storage
Tank
1 mm Screen
Screen
Backpulse
Tank
NaOCl
Citric Acid
Membrane Tank
ZW1000V3
Air Scour
Blower
Reject / neutralized
drain
Drain/
waste to
Recirculation
Pump
Reject Neutralized
Waste to Drain/Sewer
Sodium
Bisulphite
NaOH
Optional for Neutralization
Comparison of UF vs. MMF
Pretreatment
UF
Conventional
Description
• ZW 1000 IHF UF, Out/In
• 0.02 m nominal pore size
• MMF
• 5 m cartridge filter
Treated Water
Quality
• Consistent, reliable quality
• SDI < 2.5, 100% of the time,
usually < 1.5
• Turbidity:
< 0.1 NTU
• Positive barrier to particles
and pathogens - no
breakthrough
• Bacteria:
> 5 log removal
• GiardiaCyst: > 4 log removal
• Virus:
> 4 log removal
• Fluctuating quality
• SDI < 4 ~90% of the time
• Turbidity: < 1.0 NTU
• MMF not a positive
barrier to colloidal and
suspended particles.
Quality of water produced
fluctuates significantly
with respect to
particulates.
RO Membrane Systems: < 2 MegOhm
• RO rejection range of 96 – 99+% on
dissolved solids
Deionization: 2 – 18 MegOhm
– Electrodeionization (EDI) – regenerated
continuously with electricity
– Traditional DI – resin is regenerated with acid and
caustic on-site
– Traditional DI – resin regenerated off-site
Acknowledgements
• GE Water & Process Technologies: Sandy
Schexnailder