Docstoc

Zero Liquid Discharge at MacKay River

Document Sample
Zero Liquid Discharge at MacKay River Powered By Docstoc
					              Zero Liquid Discharge at
                   MacKay River
Gary Giesbrecht - February 13, 2007
  Why ZLD?
Number of disposal wells available:
  zero
Cost of 3rd party disposal:
  $100 - $150 / m3
Environmental Considerations
  Water balance improves
  More solid waste
 Water & Salt Configuration
Produced Fluids

                           BFW                        77%
   Prod’n Trt                    Steam Plant
                                                               Inj Stm


                                                             Separator
   Water Trt                           Drive Steam




                                                        Flash Drum
                                                1/3
                Dry Salt         ZLD
                                                2/3
               ZLD Process Flows
                                                      Return Condensate
 Drive Steam
                                         Air Cooled
                                         Condensers




                                                        Forced
                                                      Circulation
                                                      Crystallizer


ZLD Feed               Saturated brine

 850 t/d


                  Vertical Falling
                  Film Evaporator

                                                         Filter
                                                                      Dry Salt
                                                                     42 t/d dry
             Crystallizer
Evaporator


                            Air Cooled Condensers
               LP Steam Supply
                    Injection Steam      LP Drive Steam


HP Wet Steam
                     LV

                                             LV
                                 PV
                                                       To ZLD

                                                       To WTP




                  SG Feedwater        Cooling Glycol
The Good News
Operating at > 100% of design rate
No fouling of heat transfer surfaces or
elsewhere
No sign of SCC in 6% Mo
Silicone based defoamers effective
     but expensive
Issues, Challenges and Valuable
     Learning Opportunities
      Water Soluble Organics (WSO)
        extracted from bitumen
        highly water soluble
        non volatile at OTSG conditions
      Therefore:
        non volatile at ZLD conditions
        accumulate in Crystallizer
        purge as moisture in salt cake
WSO Accumulation
Increased viscosity of crystallizer liquor
  causes poor filterability
  complex filter design didn’t help
Decreased filter throughput
  increased TSS accumulation in crystallizer
  denser, more abrasive slurry
Abrasive Slurry

  Metal loss at:
    vortex breaker
     vapour body (incl diaphragms)
  But not:
    pump/piping
    heat exchanger
  Metallurgy
    254SMO
    AL6XN
       Responses
“Wallpaper” vapour body with new metal
Rebuild vortex breaker
Derate vapour body DP
Keep crystallizer TSS (mostly) in spec
Reduce circulation rate
Short term: Purge and dispose of liquids
Long term: Eliminate filtrate recycle


   Metal loss rate decreased to zero
Capacity Issues
Feedwater TDS
  8000 mg/L target → contract maximum
Wet steam quality
  80% → 77%
Landfill leachate
  intermittently high
Produced water TDS
  might be higher than design, obscured by
  carryover in steam
Need catch up capacity
                ZLD Expansion/Upgrade
                                                                   Return Condensate

Drive Steam



    MVC



                                                                      Crystallizer



 ZLD Feed
  1700 t/d       New
              Evaporator                                                           Exhaust
                           Evaporator   Saturated
                                          brine



                                                    Gas              Gas fired
                                                                    rotary drier
                                                                                   Dry Salt
                                                                                   80 t/d dry

                                                          Filter
                           New           Existing
 Foam Issues
Currently don’t have a vapour
compressor
  TDS upset only
  More stringent control with MVC
Foam carryover can start quickly and
empty the evaporator in minutes.
Evaporator Configuration

                               Condenser
Drive Steam


Condensate                          LT


              LT
                                           Distillate

                   Sump


                          DT
                                  Evaporator Level Upset @ 1h0m0s
       05/09/25 23:15:57                                                             05/09/26 00:15:57
100.00
100.00
 30.00                                                                                Distillate
  1.20                                                                               Tank Level
100.00
 15.00          Feed FV
               Position
                                                                                         Sump
                                                                                         Level




 0.00
 0.00      Steam         Fluid
 0.00                                                                    Outlet
 1.00       Flow        Density
 0.00                                                                    Flow
 0.00
   ** #1   (A) M08LIC365B.PIDA.PV    05/09/26 00:15:57    42.42 % (Avg @1 Min)      EVAP/CDSR
   ** #2   (A) M08LIC450B.PIDA.PV    05/09/26 00:16:33    39.91 % (Raw)       EVAP COND TANK
   ** #3   (A) M08FIC375.PIDA.PV    05/09/26 00:16:33    7.95 M3/HR (Raw)      EVAP/CDSR STM IN (M3/H
   ** #4   (A) M08DIC366B.PIDA.PV    05/09/26 00:16:33    1.05 SG (Raw)        EVAP/CDSR
   ** #5   (A) M08LIC365B.PIDA.OP    05/09/26 00:16:33    51.36 % (Raw)       EVAP/CDSR
   ** #6   (A) M08FIC366.PIDA.PV    05/09/26 00:16:33    4.53 M3/HR (Raw)      EVAP/CDSR OUT (M3/H CW
Risk of foam remains
 Additional sensors in MVC evaporator
 Silicone antifoam effective
   Need base dose plus upset dose
 Hydrostatic level/density measurement
 may not be the best
 Prevention will become essential
   for protection of vapour compressor
Solid Waste Management
  Meets Class II landfill criteria
    no free liquids
    < 2% oil & grease
    no hazardous leachate
  Project Landfill on lease
    add/close cells every few years
    started with separate salt & lime sludge
    cells
    now co-dispose both solid wastes
       Waste Salt




Filtered Saltcake




                    Rotary Drier Product
 Path Forward
MR1 ZLD expansion starts up Q2
2007
MRX configuration very similar
  MVC evaporation
  Steam drive crystallizer
  Gas fired drier
  Ample capacity
Questions?

				
DOCUMENT INFO