Imagination at work.
Anthony M. Rossi Global Boiler Product Manager GE Water & Process Technologies
Novel Terpolymer Technology for
Scale Prevention in Steam Boilers
2 GE Title or job number
3/5/2014
Why is effective control of
excessive Boiler scale
formation important to you?
Fuel costs – Maintaining design efficiency
Reliability – Avoiding tube failures & unscheduled outages
Controlling maintenance, repair & cleaning costs
Typical Boiler Plant Cost Factors
Fuel 75% Labor 9.5%
Equip.
Depreciation
9.5% Electricity
2.5%
Sewer 1.2%
Water 0.8%
Water Treatment Chemicals 1.5%
5 / GE /
Potential efficiency loss due to waterside scale
6 / GE /
Additional implications of excessive waterside scale deposits
Not just reduced efficiency, but …
Tube failures due to – o Long-term overheating
o Poor circulation leading to starvation – overheat
o Under deposit acidic or caustic corrosion
Thermal conductivity of common waterside scale deposits versus boiler steel
Thermal Conductivity
(BTU/hr per ft2 per F per inch)
Boiler Steel 310
______________________________________________
Calcium phosphate 25
Iron oxide 20
Calcium carbonate 16
Magnesium phosphate 15
Typical silicate scale <1
> 850 F
600 F o
500 F o 500 F o
Metal Wall
Tube
Metal Wall Tube
Waterside Waterside Fireside Fireside
Scale
BOILER TUBE HEAT TRANSFER
o
Design Temperature
Profile
Temperature Profile
With Scale
600 psig Boiler Overheating tube failure due to Water side scale
9
Water wall tube from a 400 psig Boiler receiving RO make-up Example of metal oxide deposit-induced overheating & under
deposit corrosion
Heavy metal oxide-dominated deposit resulted in
overheating rupture that was associated with tube
thinning due to severe under deposit corrosion
11 / GE /
Maintaining clean waterside surfaces Critical elements
1. Effective Pretreatment Removal or reduction of scale-forming ions
2. Effective cycles & dissolved/suspended solids control
Automated blowdown control
3. Effective chemical treatment
12 / GE /
Three Key Polymer Deposit Control Mechanisms
1. Dispersion - prevents particle attachment to surfaces & to each other
2. Crystal Modification - retards particle growth & size
3. Complexation – keeps scaling hardness cations – calcium & magnesium - in solution
Calcium Phosphate - Magnesium Silicate
mixed hardness deposit Untreated Condition – 4000X
Untreated condition
4000x photo
Note that the individual deposit crystals have coalesced Into a large agglomerated mass. This large particle is difficult to maintain in the boiler water and remove with blowdown.
Same hardness contaminant matrix and boiler conditions as previous slide
except for addition of an effective polymeric dispersant
Treated with carboxylated polymer
With an effective polymeric dispersant, the hardness deposit is maintained as a population of small, easily dispersed particles which are colloidal and can be removed via blowdown.
4000x photo
15 / GE /
First Generation Polymer Chemistries
CH2 C
C
O-
n
Polyacrylate
H
Polyacrylamide Polymethacrylate
O
CH2 C
C
NH2 n
H
O
CH2 C
C
O-
n
CH3
O
PMA PAA PAAM
Solus AP Boiler Terpolymer (BTP) • Patented terpolymer technology
- Acrylic acid plus two unique monomers
• Two unique sulfonated monomers enhance performance on iron, magnesium & silica
• Derived from highly successful previous generation patented GE boiler copolymer technology
Dual Sulfonated Functional groups
x
Wide spectrum deposit control performance
Deposition Rate at Heat Transfer Surface
with Solus AP versus Untreated Control
Solus AP boiler internal treatment is designed to maintain clean, essentially scale-free & efficient boiler heat transfer surfaces, even under upset and stressed conditions
Actual GE Research Boiler Test Heat Transfer Surface Comparison at 300 psig
Impact of Solus AP Treatment
Untreated control at 300 psig in hardness-dominated feedwater
Solus AP treatment at 300 psig under identical test conditions in hardness-dominated feedwater
Enhanced Transport of Iron, Magnesium, and Silica
Contaminants thru the Boiler
Reduced sludge accumulation
Reduced sludge accumulation
0
10
20
30
40
50
60
70
80
90
100
150 300 600
% F
ee
dw
ate
r Ir
on
Tra
nsp
ort
to
Blo
wd
ow
n
Boiler Pressure (psig)
Solus AP Iron Transport Performance in GE Research Boilers
Benchmark
Solus AP
Solus AP Terpolymer
Polymethacrylate Benchmark
Reduced sludge accumulation
Solus AP Magnesium Transport
Performance in GE Research Boilers
Solus AP Terpolymer
Polymethacrylate Benchmark
Reduced sludge accumulation via enhanced contaminant rejection to blowdown
0
20
40
60
80
100
120
Ca Transport % Fe Transport % Mg Transport % SiO2 Transport %
Solus AP Contaminant Transport Profile at 300 psig
Solus AP
None
Dosing Forgiveness
Feedwater upset recovery performance
Feedwater upset recovery performance
GE Research Boiler On-line deposit removal evaluation
300 psig/ Magnesium silicate-dominated deposit
Deposit formed under upset conditions without Solus AP
After Solus AP Treatment for
upset recovery
Ease of application
and control
Ease of application and control
• Stable, non-corrosive, liquid product
• Fully compatible with automated feed systems
• May be fed neat or diluted with high quality water
• Stable, non-volatile, product tracer provides
accurate & convenient dosing control & verification
• Compatible with existing polymer storage and feed
system alloys, elastomers & plastics
Field
Performance
Watertube Boiler Steam Drum Conventional All-Polymer – Prior to Solus AP
Before
170 psig D-Type Watertube Boiler August 2012 Inspection
Benchmark Polymer 2 All-Polymer Program
Steam drum surface Waterside of boiler tube
170 psig D-Type Watertube Boiler August 2013 Inspection
One year on Solus AP All-Polymer Program
Steam drum surface Tubes under belly plate
Watertube Boiler Steam Drum One Year After Initiation of Solus AP Treatment
Q&A
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