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Transcript of ONE SOURCE ONE PURPOSE MANY SOLUTIONS Utility Users Group Meeting Orange Beach, AL August 4, 2015...
ONE SOURCE ONE PURPOSE MANY SOLUTIONS
Utility Users Group MeetingOrange Beach, AL
August 4, 2015
Steam Surface Condensers: GUIDELINES & TECHNIQUES FOR THE EFFECTIVE CONTROL OF CONDENSATE DISSOLVED OXYGEN
(DO2) IN STEAM SURFACE CONDENSERSPrepared and Presented by
Darren M. NightingaleDirector of Engineering, TEi Condenser Division
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
Darren M. Nightingale Director of Engineering,
Condenser Division
Telephone: 323.838.1173 (Office)
Telephone: 323.627.5527 (Cell)
E-Mail: [email protected]
THERMAL ENGINEERING INTERNATIONAL, INC.
10375 SLUSHER DRIVE
Santa Fe Springs,
CA 90670-3748
Introduction
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
GUIDELINES & TECHNIQUES FOR THE EFFECTIVE CONTROL OF CONDENSATE DISSOLVED OXYGEN IN
STEAM SURFACE CONDENSERS:
Low levels of dissolved oxygen in the condensate produced within steam surface condensers, is highly desirable and an increasingly important aspect related to the efficient operation of today’s power plants. The presence of high levels of dissolved oxygen within condensate can quickly contribute to accelerated corrosion & additional treatment requirements as well as increased maintenance and operational challenges. Under certain operating conditions, steam surface condensers can be expected to produce condensate with pre-defined, or guaranteed, levels of dissolved oxygen. However, these levels can only be achieved by a combination of following design guidelines and not exceeding operational limitations - this is not always the case. This 20min presentation includes the latest design guidelines, operational limitations and general considerations, as well as practical techniques, for minimizing dissolved oxygen levels for condensate produced within the condenser.
Abstract - Overview
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
• WHAT? – Is Dissolved Oxygen?• WHY? – Is DO2 a Problem?
• WHERE? – Does DO2 Come From?• HOW? – Should My Condenser Perform?• WHEN? – Does ‘High’ DO2 Occur?
• HELP!? – Can I Reduce my DO2?!
Presentation Agenda
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
WHAT? – Is Dissolved Oxygen?
• Oxygen: Colorless, Odorless & Tasteless Gas.• Occurs in its Free State as a Gas, O2
• Liquid only at -297.4°F. • Oxygen in Air is 20.9% by Volume.• Oxygen in Air is 23.1% by Mass.• DO2 in Air Saturated Make-up: 8,000 – 14,000 ppb O2
…the amount of free (NOT chemically combined)
oxygen dissolved in the condensate, usually
expressed in milligrams per liter, parts per million/billion,
or percent of saturation. Often called DO or DO2.
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
WHAT? – Is Dissolved Oxygen?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
Power Plant System Diagram - FOSSIL
Cooling TowerDeaerator
LPHeaters
Air Preheater
Condenser
Stack
Flue gasdesulfurization
Electrostaticprecipitator or Baghouse
Steam Turbine
Utility Boiler
Air
Superheater
Reheater
Economizer
FuelFiring
System
Generator
Low NOx Burners
SCR (DeNOx)
Pulverizer
Boiler Tubes
HPHeaters
WHY? – Is DO2 a Problem?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
LOWPRESSURETURBINE
HIGHPRESSURETURBINE
CONDENSER
BOILER
LOWPRESSUREHEATER 4
LOWPRESSUREHEATER 3
HIGHPRESSUREHEATER 2
HIGHPRESSUREHEATER 1
DA
Nuclear / Coal Fired
Typical Steam Power Plant Cycle
WHY? – Is DO2 a Problem?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
WHY? – Is DO2 a Problem?
• HENRY’S LAWBased on Henry's Law formulated by the English chemist William Henry states that at a given temperature, the solubility of a gas is directly proportional to the pressure of the gas directly above the liquid.
• LE CHATELIER’S PRINCIPLELe Chatelier's principle states that a change in any of the factors determining equilibrium will cause the system to adjust to the changes in order to restore equilibrium.
Le Chatelier's principle predicts that the solubility of a gas willincrease as a system loses heat, and will decrease as a system gains heat.
• Steam Surface CondenserNeeds to operate with maximum efficiency to remove as much Dissolved Oxygen as possible, however, this IS limited by Operational Parametrics!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
WHY? – Is DO2 a Problem?
• CORROSION!!• pH Levels,• Seal Faces,• Cavitation Pumps, etc.
• 5ppb+ can induce pitting corrosion!!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
• LP Exhaust – Steam.• LP Exhaust – Shaft Seals.• Gland Seal Steam.• Steam Bypass (CCGT).
> Desuperheater• Entrained in Condensate.• ‘Cold Water’ Make-Up.
Especially if TMU < TSat
• Air In-Leakage.• Shell Cracks.• Gasket Leaks.• Etc., etc.
WHERE? – Does DO2 Come From? Problem?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
WHERE? – Does DO2 Come From? Problem?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
• 7 ppb … 0.005 cc/l• 14 ppb … 0.010 cc/l• 21 ppb … 0.015 cc/l• 42 ppb … 0.030 cc/l
• Most Condensers should not exceed 42ppb under practical operating conditions. [BWR-Nuke, 10-50ppb]
• Condensers can achieve as low as 7ppb and 14ppb given stable operation at the Design conditions (100% Duty!).
• Condensers do NOT perform well when they…• …Operate at LOW LOAD Conditions!• …Cycle or have Transient Operation!• …Have to deal with High Quantities of Make-Up < TSat!!
HOW? – Should My Condenser Perform?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
KNOW THE ‘3/7 - 5/14’ RULE!• To Maintain ≤ 7ppb
• ‘Cold’ Make-Up < TSat.
• < 3% Steam Flow.• To Maintain ≤ 14 ppb
• ‘Cold’ Make-Up < TSat.
• < 5% Steam Flow.• HEI > DO2 Curves > Guarantees!
• Figures 3 & 5.• 7ppb and 14ppb Curves.• C.W. Inlet Temp., Duty & Back-Pressure.
HOW? – Should My Condenser Perform?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
HEI: Standards for Steam Surface CondensersHEI (Heat Exchange Institute)Standards for Steam Surface Condensers
– 11th Edition [Oct. 2012]– Addendum 1 [Aug. 2014]– Design Guidelines for DO2
– Section 4.3 – O2 Condensate– Sample Calculations– Venting Capacity– Performance Curves
HEI = Guaranteed Performance!!!
HOW? – Should My Condenser Perform?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
HEI Figure 3Absolute Pressure Limit Curves for Oxygen Content
Saturation Pressure versus C.W. Inlet Temperature
Predicts Condensate Dissolved Oxygen Content at
Curve A ≤ 7ppb
Curve B ≤ 14ppb
Superimpose Figure 3 on Condenser Performance Curves (versus Load)…
HOW? – Should My Condenser Perform?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
HEI Figure 5Absolute Pressure Limit Curves for Guarantees.
Saturation Pressure versus C.W. Inlet Temperature.
Predicts Cut-Off Point and Zero Load Performance.
Curve A ≤ Cut-Off
Curve B ≤ Zero LoadSuperimpose Figure 3 and Figure 5 onto Condenser Performance Curves – C.W. Inlet, Duty & Back-Pressure vs DO2 Levels
HOW? – Should My Condenser Perform?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
HEI Figure 5
Cut-Off to Zero Load must be reflected on Performance Curves to predict DO2 Performance!
NOTE: 5°F TTD is a Guarantee Limit!!
HOW? – Should My Condenser Perform?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
PERFORMANCE CURVES Back-Pressure (0.5-6.0 inHgA)
Heat Duty (0-120%)
Circ. Water Temps. (70-110°F)
Cleanliness Factor (85%)
Curve A ≤ 7ppb
Curve B ≤ 14ppb
Performance Curves should be provided by all Condenser
OEM’s for predicting your DO2 performance!!
HOW? – Should My Condenser Perform?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
• Do Not Address Leaks! i.e Fix Leaking Gaskets, etc.• Make-Up <Tsat
• 3%+ of WS >> 7ppb+• 5%+ of WS >> 14ppb+
• Make-Up is in Poor Location• Below Bundle!• NO Reheat!!
• Baffle/Elbow vs Spray Pipe• Operational Parametrics
• LOW LOADS!• Cycling / Transient• Low C.W. Inlet (Winter)
WHEN? – Does ‘High’ DO2 Occur?
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
• 1. Connection (Re)Design Convert Baffles to Spray Pipes! Revised Location to ABOVE Bundle, not side, or below Install a properly designed Spray Pipe (Reheat)
• 2. Install a Hotwell Sparger High Make-Up (5%+ Q) &/or Low Make-Up Temp (<TSat) Operational Conditions (Low Load, Cycle, Low C.W. Temps)
• 3. Install a Vacuum Deaerator High Make-Up (5%+ Q) &/or Low Make-Up Temp (<TSat) Achieve <5ppb
HELP?! – Can I Reduce My DO2?!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
1. CONNECTION (RE)DESIGN• Effective for
• Improve Reheat Levels.• Improve Deaeration.• Avoid Baffles/Elbows.• Use Spray Pipes (proven).• Re-Engineer Existing Baffles.• Re-Route Internally (if Head!).• Follow HEI & EPRI Guidelines.• Locate above Bundle.• not below, or at side• Improve Distribution• Improve Reheat!• Use St/St Piping (longevity).
• $ Lowest Cost Option (Outage).
HELP?! – Can I Reduce My DO2?!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
1. CONNECTION (RE)DESIGN &/OR (RE)LOCATION
HELP?! – Can I Reduce My DO2?!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
1. CONNECTION (RE)DESIGN &/OR (RE)LOCATION
HELP?! – Can I Reduce My DO2?!
Spray Pipe above vs Baffle on side of Bundle!! Increased Distribution Area & Volume. Improved the Contact/Residence Time. Reheating was vastly improved. Dissolved Oxygen liberated IN Bundle. Dissolved Oxygen removed from Bundle via
Air Draw Off, Vent Duct & Vacuum Equipment Eliminated “Spikes” in DO2 during Make-Up. Reduced DO2 by up to 21 ppb.
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
2. INSTALL HOTWELL SPARGER• VERY Effective for
• Raising Condensate Temperature.• START-UP!
• Use for Cold Start-Up.• Use of Hot Start-Up.
• Design for 30-60 mins. to TSat.
• LOW (Transient) LOADS (Reheat).• LOW C.W. Temperatures (Winter).• Simple Control (On/Off).• Popular in Combined Cycle Plants.• And.…Base Loaded Fossil Units that now Cycle!• Auxiliary Steam (typ. 50psiG @ 350°F & 1,200+ Btu/lb)• When to Operate a Hotwell Sparger? V. IMPORTANT!
• $$ Medium Cost Option (Outage).
HELP?! – Can I Reduce My DO2?!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
Typical Hotwell with Steam Sparger Piping to control dissolved
Oxygen in condensate during Start-Up, Low
Loads & Low C.W. Temperatures.
2. INSTALL HOTWELL SPARGER
HELP?! – Can I Reduce My DO2?!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
HELP?! – Can I Reduce My DO2?!
WHEN TO OPERATE A HOTWELL SPARGER?
• LOW LOADS!• LOW DUTY!• LOW C.W. INLET!• HIGH MAKE-UP!• CYCLING!• ONE BUNDLE
OPERATION!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
3. INSTALL A VACUUM DEAERATOR
• Highly Effective for
• Large Volume Make-Up.• 5%+ of Steam flow
• Low Temp Make-Up.• Make Up <TSat
• Spray & Tray (proven).• Robust (Range of Conditions).• Uses Steam from Condenser.• OR, Auxiliary Steam.• Excellent for Cycling/Transient.• Condenser Mounted !• Operates Continuously.
• $$$ Highest Cost Option (PROJECT)
HELP?! – Can I Reduce My DO2?!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
3. INSTALL A VACUUM DEAERATOR
HELP?! – Can I Reduce My DO2?!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
SUMMARY• Know Your Condenser!• OEM Performance Curves;• w/ HEI 7 & 14 ppb Curves.• Address Air In Leakage.• For ‘Cold Water’ Make-Up.
Especially if TMU < TSat
• Make-Up Design (Spray Pipe)• …and Location (above Tubes)• Use of Hotwell Sparger.• Vacuum Deaerator?• Always Monitor DO2.• Address ‘High’ DO2!!!
SUMMARY – Dealing with Condensate DO2
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
THANK YOU FOR YOUR TIME!!
THANK YOU!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved
QUESTIONS?& ANSWERS!
QUESTIONS? & ANSWERS!
© 2015 Information contained herein is proprietary and confidential to Babcock Power Inc. All Rights Reserved