Reducing Energy & Water In Your Boiler House Charles Astbury Commercial Operations GE Water & Process Technologies

Transcription

1 Reducing Energy & Water In Your Boiler House Charles Astbury Commercial Operations GE Water & Process Technologies Presented by

2 What areas can you impact? Reduce Blowdown Saves water and energy Recover heat from Blowdown Saves energy Recover Condensate Saves water and energy Maintain clean water side & fire side Saves Energy

3 Cycles of Concentration

4 Cycles of Concentration

5 Cycles of Concentration 8 2 = 4

6 Impact of blowdown on water At 10 cycles have 10% blowdown At 20 cycles have 5% blowdown At 50 cycles have 2% blowdown At 100 cycles have 1% blowdown 98 MT/Hr Fuel BFW 100 MT/Hr C=50 CBD At 10 Cycles BD = 10.9T/Hr 2% 2 MT/Hr IBD

7 Impact of blowdown on efficiency BTU Value of Blowdown Heat BD Heat Lost, $/yr With No Heat Recovery With Flash Tank Bottoms With Flash Tank and Heat Exch Cycles % BD FW BD klb/hr klb/hr 10 10% 111,111 11,111 $367,531 $147,947 $11, % 105,263 5,263 $174,093 $70,080 $5, % 102,041 2,041 $67,506 $27,174 $2,174 Basis Steam 100,000 lb/hr Pressure 600 psi 50 cycles versus 10 cycles saves $300,000/yr 50 cycles versus 10 cycles saves $120,000/yr 50 cycles versus 10 cycles saves $10,000/yr

8 How do you reduce blowdown? Turn it down... Increase deposition risk High performance chemicals Decline in steam purity Steam purity is a direct function of boiler water dissolved solids content Improve makeup water quality

9 Discussion Topics BFW & steam purity requirements Pretreatment Methods Membrane solutions for boiler RO in front of demineralizers RO replacement of softeners

10 Begin the feedwater system design process by defining your end state water quality needs What level of water purity do the boiler and steam processes require?

11 ASME GUIDELINES Table 1 - Watertube Boiler with Superheater/Turbine All Pressures: FW dissolved oxygen < 7 ppb (with DA) Feedwater ph: (0-900 psig) / ph (> 901 psig) Boiler Feedwater Boiler Water Drum Pressure (psig) Iron (ppm Fe) Copper (ppm Cu) Total Hardness ppm CaCO Silica ppm SiO Total alkalinity ppm CaCO ( ) ( )( ) Specific Conductance ( μmhos/cm) (Unneutralized) 0 to to to to to to 1,000 1,001 to 1,500 1,501 to 2, Note: All limits are expressed less than the value specified (e.g., < ppm)

12 GE Steam Purity Recommendations for Utility Steam Turbines with Reheat Steam Parameter All Volatile Treatment Phosphate Treatment Equilibrium Phosphate Treatment Sodium, ppb <3 <5 <3 Cation Conductivity, us/cm <0.15 <0.3 <0.15 Silica, ppb <10 <10 <10 Chloride, ppb <3 <3 <3 Sulfate, ppb <3 <3 <3 Total organic carbon, ppb * Steam Purity Recommendations for Utility Steam Turbines, GEK 72281A, July, 1996 <100 <100 <100

13 BFW quality considerations Boiler pressure and superheater/turbine steam purity requirements generally define pretreatment and feedwater quality requirements. In general: Softened or single pass RO < 600 psig Demineralized or RO/EDI > 900 psi RO Reverse Osmosis EDI - Electrodeionization

14 Technologies to Improve Makeup Water Purity Softeners Dealkalizers Demineralizers Reverse Osmosis Systems

15 Resin Based Pretreatment Performance System Softener Dealkalizer Standard two-bed demineralizer Two-bed demineralizer with counterflow regeneration Two-bed demineralizer with mixed bed polisher Typical Effluent Quality ppm hardness (no TDS reduction) 50 to 90% alkalinity reduction (no TDS reduction) <10 μmho <200 ppb silica <5 μmho <50 ppb silica <0.1 μmho <10 ppb silica Typical Boiler Operating Pressure (psig) 0 to to to to 1,200 1,200+

16 Zeolite Softening & Dealkalization Advantages Inexpensive Cap & Op costs Simple-to-operate Durable Safe & inexpensive sodium chloride regenerant Limitations No reduction in TDS FW quality can limit boiler cycles Not suitable for high-pressure boiler operation (> 900 psig) No silica reduction No alkalinity reduction without dealkalizer

17 Resin-based demineralization Advantages Limitations Reduction in all dissolved solids Enables high cycles operation Suitable for high-pressure boilers Can tailor to specific purity needs Excellent silica rejection Excellent alkalinity/co2 rejection Strong acid/caustic required for regeneration Caustic costs high & variable Limited anion resin life Silica and sodium leakage Manpower intensive Operating costs directly proportional to TDS

18 Reverse Osmosis Advantages Rejection of all dissolved solids Operating costs not directly dependant on TDS Enables high cycle boiler operation Requires no chemical regenerants (acid/caustic) Not labor intensive Versatile pairings with resin-based systems Ideal for mobile applications Limitations RO alone not suitable for HP boiler feedwater > 1000 psig with turbine Higher electrical costs than resinbased systems (high-pressure pumps) Generates significant reject stream (typically 20 30% of input stream) Does not reject CO2 (g)

19 What are the tools available? Feedwater Economic Models CCR Bankbook BoilerCalc Condensate Modeling System

20 What are the tools available? Feedwater Economic Models CCR Bankbook BoilerCalc Condensate Modeling System Touch on this Focus on this

21 CCR Bankbook

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25 Potential Membrane Solutions for Boiler Systems 1. RO in front of existing demineralizers 2. RO in front of, or to replace existing softeners 3. New plant RO/MB or Demin/MB? 4. 2 pass RO/EDI to replace resin-based demineralizer - Mixed-bed quality train 5. Ultrafiltration in front of demin. or RO to replace traditional filtration/clarification

26 RO ahead of Existing Demin Reduced acid & caustic regenerant costs 90 95% reduction in regenerant usage is typical 10 to 15% more feedwater production each month 90% less (high TDS) regenerant waste Extended ion exchange resin life 40 50% extension in resin life typical Much longer regen. cycles & reduced iron/organic fouling Improved feedwater & steam quality Sodium & silica slippage & breaks reduced Detailed economic & environmental benefit analysis and modeling is required

27 Key input variables for modeling & analysis TDS of influent water Capital equipment costs Caustic and acid costs Electrical power rates Influent water costs Sewer costs o o o Economic Volume or Vol/TDS-basis? Can plant reuse RO reject? Credits or incentives for reuse Regenerant neutralization costs Differential labor costs Environmental Reduction of acid/caustic inventory Safety - chemical exposure Water scarcity issues Discharge/permitting issues

28 Presented by Economic Models

29 Two New powerful tools for quick evaluation providing value to our customers

30 Data input section

31 Result output section

32 Soft saving section

33 Saving Water & Energy is a Big Win in Every Way, and the creative use of Membrane solutions for Boilers can help you to make it happen at your facility! These are just two of the many possibilities Thank you for your time & attention