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Steam and Water Sampling. “Sampling 101” and Sample System Components. Utility Market Components. Back Pressure/Relief Valve - BPRV ™. Sample Coolers. Cation Resin Columns. Thermal Shut Off Valve - TSV ™. Variable Pressure Reducing Elements VREL ™. Steam and Water Sampling. Why sample?

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utility market components
Utility Market Components

Back Pressure/Relief Valve - BPRV™

Sample Coolers

Cation Resin Columns

Thermal Shut Off Valve - TSV™

Variable Pressure Reducing Elements

VREL™

steam and water sampling1
Steam and Water Sampling
  • Why sample?
    • Monitor/adjust water chemistry to:
      • Maximize heat transfer efficiency
      • Maximize time between chemical cleanings
      • Maximize boiler life and turbine life
      • Minimize operating & maintenance costs
important sample conditioning parameters
Important Sample Conditioning Parameters

“The Primary objective of any sampling system is to transport and condition a sample without altering the characteristics of interest. The system parameters which need to be controlled are velocity, pressure and temperature.”

Source: EPRI CS-5164, April 1987

sample point selection cc system
Sample Point Selection, CC System
  • Gas Turbine
  • Generators
  • Steam Turbine – Main Steam SiO2, Na, CC
  • HRSG – Boiler Drum - pH, SC, PO4, SiO2, Na, Chloride
  • Condenser – pH, SC, CC, Na, SiO2, DO
  • Feed water – SC, CC, Na, pH, SiO2
  • Boiler Feed Pump
  • Not shown:
  • Deaerator – DO, pH, SC, CC
  • Economizer – pH, CC
sample point selection
Sample Point Selection

Based on:

  • System design
  • Subject constituents
  • Chemical treatment
  • System specific problems
sample velocity
Sample Velocity
  • Velocity should be 5-6 ft/sec (1.8 m/sec) to maintain equilibrium of ionic and particulate components
  • Ideally, sample lines in sample system should be 1/4” (6.35mm) tube; flow rate at of about 1200 cc/min and velocity at 6 fps (1.8 m/s).
  • Flow rate of 3300 cc/min in a 3/8” (9.5mm) tube with .065” (1.65mm) wall is 6 fps
sample lag time
Sample Lag Time

Flow rate Velocity

Tube Size cc/min Ft/sec Lag Time/1000’

1/4”x.042” wall 500 2.5 6.5 min

12006.02.8 min

3/8”x.065”wall 500 0.9 18.7 min

1200 2.2 7.6 min

16663.05.6 min

Theoretically correct > 3300 6.0 2.8 min

But not practical

1/2”x.125 wall essentially equal to 3/8”x.065 wall

6.0 ft/sec is approximately 1.8 m/sec

temperature control primary coolers
Temperature Control – Primary Coolers
  • Primary sample cooler approach temperature: 5 ºF (2.8 ºC) of coolant temperature
  • Corrosion resistant tubing (18% Cr, 8% Ni), 316 SS, internal baffles
  • Coil tubing to meet velocity requirements (1/4”, 3/8” O.D.) (6.35mm, 9.5mm)
sample coolers2
Sample Coolers
  • High Efficiency, Counter Flow Design
  • All Stainless Steel Construction
  • Single Gasket Design
  • 100% Hydrostatic Testing, Tube and Shell
  • Variety of Shell and Tube Materials Available
sample coolers materials

Standard Shellside Materials:

  • 316/316L Stainless Steel
  • 304 Stainless Steel
  • 90/10 CuproNickel
Sample Coolers - Materials

Standard Tubeside Materials:

  • 316/316L Stainless Steel
  • Alloy 625 (Inconel 625)
special sample coolers
Special Sample Coolers
  • Special sample coolers
    • Cooling water with elevated chlorides and DO such as cooling tower water or potable water sources
    • High temperature samples
    • Use Inconel 625 coils, CuNi shells
sample coolers materials1
Sample Coolers - Materials

Optional Tubeside Materials, short coil only:

  • Alloy C-276 (Hastelloy)
  • Alloy 200 (Nickel)
  • Alloy 400 (Monel)
  • Titanium
  • Zirconium
  • 310SS

Optional Shellside Materials:

  • 316/316L SS

Additional materials may be possible.

Orbitally welded long coils currently available in Zirconium

competitive products
Competitive Products
  • Waters Equipment – USA
  • Dr Thedig - Germany
  • Forbes Marshall – India
  • Lowe – U.K.
  • DKK – Japan
  • Nikkiso – Japan/Taiwan
  • Eurosysteme
  • Watcom
  • Westhoff
competitive products1
Competitive Products
  • Analyzer manufacturers
    • ABB
    • Yokagawa
    • Emerson
    • Swan
  • Others –local
competitive products2
Competitive Products
  • May not offer performance calculations
  • Carbon steel shells
  • Thin wall shells (drawn)
  • May not offer dual baffle
  • Tie-rod designs
  • May offer dual-tube units which don’t work for ASTM recommended flows
important sample conditioning parameters secondary cooling
Important Sample Conditioning Parameters – Secondary Cooling
  • Secondary cooling
    • Recommended to control sample temperature to 77 °F +/- 1 °F (25 °C +/- .5 °C)
    • Analyzer temperature correction algorithms should be evaluated for:
      • Suitability given the expected sample matrix
      • Sample temperature range
      • Sensitivity
      • Potential correction factor error
important sample conditioning parameters secondary cooling1
Important Sample Conditioning Parameters – Secondary Cooling
  • Isothermal Bath
    • Coils in chilled water bath
      • Chiller with hot gas bypass
      • Thermal bypass valves
    • Must have good mixing in bath
    • Bypass valves can be problematic
important sample conditioning parameters secondary cooling2
Important Sample Conditioning Parameters – Secondary Cooling
  • Individual sample coolers
    • Individual, high efficiency coolers for each sample stream
    • Chilled water supply with hot gas bypass 75-76 °F +/- 1 °F (23.9 –24.4 °C)
    • Hot gas bypass can add heat into system if samples are sub cooled
important sample conditioning parameters secondary cooling3
Important Sample Conditioning Parameters – Secondary Cooling
  • Field Study
    • 19 Fossil and Nuclear plants
    • 11 isothermal bath systems
    • 8 individual cooler systems
    • Isothermal baths averaged 77 °F +/- 5 °F ( 25 °C +/- 2.7 °C)
    • Max deviation 28 °F (15.6 °C)
    • Individual secondary coolers averaged 77 °F +/- 2 °F ( 25 °C +/- 1 °C)
    • Max deviation 5 °F (2.7 °C)
important sample conditioning parameters1
Important Sample Conditioning Parameters
  • Pressure Reduction
    • All Wetted Parts Stainless Steel
    • Needle valves for 500 psig and less
    • Rod-in-tube for pressures greater than 500 psig
    • Drag valves and capillary tubes are prone to plugging
    • Adjustable rod-in-tube preferable
      • Cleanable in place
      • Adjust to proper flow
competitive products3
Competitive Products
  • Look alike or similar rod-in-tube designs – may or may not operate well
  • Capillary tubes - plug
  • Drag valves – plug - expensive
  • Multiple needle valves – wear – same price as VREL
important sample conditioning parameters2
Important Sample Conditioning Parameters
  • Flow Control
    • EPRI/ASTM recommends a Rod-in-tube pressure reducing device and backpressure valve combination
    • Constant sample velocity/flow
      • Reduced possibility of crud bursts
      • Constant flow to on-line analyzers for repeatable analysis results
    • BP/RV acts as a “shock absorber”
bp rv
BP/RV
  • Assures Constant Pressure/Flow to Analyzers
  • Protects System From Over Pressurization
  • Large Orifice Won’t Plug or Stick
  • Constant Pressure Over Wide Flow Range
  • Regulates to 20 psi (standard)
  • Metallic Wetted Parts – Stainless Steel
  • Elastomer – Viton
  • Seat – PEEK
  • Optional pressure settings: 5 psig (0.3 barg), 7 psig (0.5 barg), 12 psig (0.8 barg), 28 psig (1.9 barg), 42 psig (2.9 barg), 60 psig (4.1 barg)
competitive products4
Competitive Products
  • Tescom
  • Go
  • Coniflo
    • Not designed specifically for the application
thermal shut off valve tsv
Thermal Shut Off Valve (TSV)
  • Protects analyzer cells
  • Protects operators
  • Mechanically Actuated, Automatic Shut-Off for Thermal Protection
  • Visual Trip Indication
  • Optional Switch for Remote Indication
  • Requires Manual Reset
  • Latching Design
  • No Pneumatic or Electrical Power Required
competitive products5
Competitive Products
  • Wax valves – automatically reset or are one use
  • Sensor, controller and solenoid valve – expensive – problematic
  • Bi-metal, mechanical or electro-mechanical – trip point is not accurate, prone to failure
thermal shut off valve tsv1
Thermal Shut Off Valve (TSV)
  • Standard Wetted Materials
    • 316 Stainlesss Steel, Viton, PEEK
  • Optional Elastomer
    • Kalrez
  • Standard Temperature Set Point = 120° F (49° C)
  • Optional Temperature Set Points = 104° F (40° C), 140° F (60° C), 160° F (71° C), 153° F (67° C), 194° F (90° C), 203° F (95° C), 210° F (99° C)
slide52

Cation Resin Column

  • Ion exchange resin uses porous beads that have a Hydrogen ion that can be exchanged for a cation.
  • R = the resin and H = hydrogen ion
  • 2R-H +Ca+2 <=> R2-Ca +2H+
  • The Resin column acts somewhat like a “filter”
  • Reduces the “masking” effect of ammonia
  • Proper length – dia. Ratio for good ion exchange
  • Prevents “channeling”
  • Refillable
slide53

Cation Resin Column

  • Major Cations in water
    • Ca+2
    • Mg+2
    • Na+
    • Fe+2
    • Cr+6
    • Ni+3
    • Cu+2
    • Zn+2
    • NH4+
competitive products6
Competitive Products
  • Many, varied
  • Resin is mostly the same but length to diameter ratio is key to proper ion exchange
  • A larger column may offer more resin but poorer ion exchange
  • Tubes are usually thinner, poor quality
astm standards
ASTM Standards

ASTM 3370 – Standard Practices for sampling water from closed conduits

ASTM 5540 - Standard Practices for flow control and temperature control for On-Line water sampling and analysis

Shortcut to ASTMD5540.pdf

ASTM 1066 – Standard practices for sampling steam

Note:

ASTM 1192 – Similar to D5540 - suspended

conclusion
Conclusion

“ A properly designed sample system transports and conditions samples from the point of extraction to analysis points without altering the characteristics of interest”

sample line fouling solutions
Sample Line Fouling Solutions

Traditional sintered element filter, low temperature

Strainer, high pressure and temperature

sample line fouling solutions1
Sample Line Fouling Solutions
  • Sludge trap
    • Designed to “drop out” particles rather than trap them and hold them in the flow stream.
    • Installed upstream of primary sample cooler
    • Usually limited to boiler drum or similar samples
    • Requires periodic flush to drain and piping to safe location (HP header, blow down tank)
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