Bkout - Reducing Energy and Water in Boiler House · PDF fileWith Flash Tank Bottoms With...
Transcript of Bkout - Reducing Energy and Water in Boiler House · PDF fileWith Flash Tank Bottoms With...
Presented by
Charles AstburyCommercial Operations
GE Water & Process Technologies
Reducing Energy & Water In Your Boiler House
What areas can you impact?
• Reduce Blowdown– Saves water and energy
• Recover heat from Blowdown– Saves energy
• Recover Condensate– Saves water and energy
Cycles of Concentration
Cycles of Concentration
Cycles of Concentration
82
4=
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
Fuel
At 10 Cycles BD = 10.9T/HrCBD
IBD
BFW100 MT/Hr
2 MT/Hr
C=50
98 MT/Hr
2%
CBD
IBD
BFW100 MT/Hr
2 MT/Hr
C=50
98 MT/Hr
2%
Impact of blowdown on efficiency
Cycles % BD FW BDWith No Heat
RecoveryWith Flash Tank
Bottoms
With Flash Tank and Heat Exch
klb/hr klb/hr10 10% 111,111 11,111 $367,531 $147,947 $11,83620 5% 105,263 5,263 $174,093 $70,080 $5,60650 2% 102,041 2,041 $67,506 $27,174 $2,174
BasisSteam 100,000 lb/hrPressure 600 psi
BD Heat Lost, $/yrBTU Value of Blowdown Heat
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
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
Discussion Topics
BFW & steam purity requirements
Pretreatment Methods
Membrane solutions for boiler– RO in front of demineralizers– RO replacement of softeners
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?
ASME GUIDELINESTable 1 - Watertube Boiler with Superheater/Turbine
All Pressures: FW dissolved oxygen < 7 ppb (with DA)Feedwater pH: 8.3 - 10.0 (0- 900 psig) / pH 8.8 - 9.6 (> 901 psig)
0 to 300300 to 450451 to 600601 to 750751 to 900901 to 1,0001,001 to 1,5001,501 to 2,000
DrumPressure
(psig)Iron
(ppm Fe)
0.1000.0500.0300.0250.0200.0200.0100.010
Copper(ppm Cu)
0.0500.0250.0200.0200.0150.0150.0100.010
TotalHardness
ppm CaCO
0.3000.3000.2000.2000.1000.0500.0000.000
SilicappmSiO
15090403020821
Totalalkalinity
ppm CaCO
350300250200150100
--
SpecificConductance µmhos/cm)
(Unneutralized)
350030002500200015001000150100
Boiler Feedwater Boiler Water
3 2 3( ))( ( ) (
Note: All limits are expressed “less than” the value specified (e.g., < 0.100 ppm)
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
<100 <100 <100
* “ Steam Purity Recommendations for Utility Steam Turbines”, GEK 72281A, July, 1996
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 OsmosisEDI - Electrodeionization
Technologies to Improve Makeup Water Purity
Softeners
Dealkalizers
Demineralizers
Reverse Osmosis Systems
Resin Based Pretreatment Performance
Softener 0.2-1.0 ppm hardness (no TDS reduction)
0 to 600
Dealkalizer 50 to 90% alkalinity reduction (no TDS reduction)
0 to 600
Standard two-bed demineralizer
<10 µmho <200 ppb silica
400 to 900
Two-bed demineralizer with counterflow regeneration
<5 µmho <50 ppb silica
900 to 1,200
Two-bed demineralizer with mixed bed polisher
<0.1 µmho <10 ppb silica
1,200+
System Typical EffluentQuality
Typical BoilerOperating
Pressure (psig)
Zeolite Softening & Dealkalization
AdvantagesInexpensive – Cap & Op costs
Simple-to-operate
Durable
Safe & inexpensive sodium chloride regenerant
LimitationsNo 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
Resin-based demineralization
Advantages
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
Limitations
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
Reverse OsmosisAdvantages
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
LimitationsRO alone not suitable for HP boiler feedwater > 1000 psig with turbine
Higher electrical costs than resin-based systems (high-pressure pumps)
Generates significant reject stream(typically 20 – 30% of input stream)
Does not reject CO2 (g)
What are the tools available?
• CCR Bankbook• Feedwater Economic Models• BoilerCalc• Condensate Modeling System
What are the tools available?
• CCR Bankbook• Feedwater Economic Models• BoilerCalc• Condensate Modeling System
Touch on this
Focus on this
CCR Bankbook
Potential Membrane Solutions for Boiler Systems1. 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
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
Key input variables for modeling & analysis
TDS of influent water
Capital equipment costs
Caustic and acid costs
Electrical power rates
Influent water costs
Sewer costso Volume or Vol/TDS-basis?o Can plant reuse RO reject?o Credits or incentives for reuse
Regenerant neutralization costsDifferential labor costs
Reduction of acid/caustic inventory
Safety - chemical exposure
Water scarcity issues
Discharge/permitting issues
Economic Environmental
RO preceding DemineralizerApproximate TDS Breakeven
360500$2.00$1.50
310470$2.00$.50
275405$1.00$.50
230380$.50$.50
Flow, 450 gpm
Flow,
50 gpm
Waste Water, $/kgal
Raw Water, $/kgal
Presented by
Economic Models
Two New powerful tools for quick evaluationproviding value to our customers
Data input section
Result output section
Soft saving section
Saving Water & Energyis 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