Confidential and proprietary to Garratt-Callahan Company
Sugar Boiler Water Treatment Technology
2010 Jamaica Association of Sugar Technologists(JAST)
Confidential and proprietary to Garratt-Callahan Company
Bagasse Boiler
Confidential and proprietary to Garratt-Callahan Company
Typical Firetube Boiler
3
Confidential and proprietary to Garratt-Callahan Company4
Water-Tube Units– Water passes through (inside) tubes.– Used in power generation and industrial process steam.– Used for high pressure and high steam demand applications,
also used with low demand application too.– Best suited for large plants with steam turbines.– Very high and fast steaming rate, with low contained volume
of water.
Boiler Types
Confidential and proprietary to Garratt-Callahan Company5
Water-Tube Units– Has large square feet of heating area.– Responds quickly to fluctuating steam loads.– Requires more care in water treatment, as tubes can get
plugged with scale, inhibiting circulation.– Has a steam drum and mud drum with interconnecting tubes.– Must be treated with preconditioned water. e.g. Softened.
Boiler Types
Confidential and proprietary to Garratt-Callahan Company6
Water-Tube Unit Circulation
Boiler Types
Boiler Types
7
Water-Tube Unit Types
Boiler Types
8
Water-Tube Unit Types
Boiler Types
9
Water-Tube Unit Types
Boiler System Overview
10
Feed WaterTank or
Deaerator
Boiler
Ion Exchange
Makeup(Pretreatment)
BottomBlowdown
Steam
Condensate
FeedwaterPump
Load
SurfaceBlowdown
Confidential and proprietary to Garratt-Callahan Company
Condensate
• Condensate from the evaporators, pans and turbines supply in excess of 150% of the boiler feed water
• Condensate can be contaminated with sugar• Sugar contamination
– Drops the pH to acid levels under pressure.– Low pH feed water corrodes the tubes.– Corroded iron is laid down as scale on the tubes.– Sugar can caramelize and be laid down as carbon scale on the
tubes
Confidential and proprietary to Garratt-Callahan Company 12
Pre-Treatment Systems Sodium Cycle Cation Exchange
Strong AcidCation
ExchangerSodiumCycle
2HCO3
SO4
2Cl2NO3
CaMg2Na
CaMg2Na
SiO2
Influent
RegenerantNaCl
Regenerant Waste
CaCl2MgCl2NaCl
To Process
NaHCO Na2CO3Na2SO4
NaCl NaNO3SiO2
Make-up WaterSoftener
13
Elution Study
14
•Use a graduated cylinder and a Salometer
•Take samples every 5 minutes and plot curve.
Confidential and proprietary to Garratt-Callahan Company15
Deaerating Heaters - Oxygen Removal .005 cc/L 7 pbb.
Confidential and proprietary to Garratt-Callahan Company
Dissolved oxygen:
– Can cause corrosive pitting attack on feed water/boiler surfaces.
– Usually caused by dissolved oxygen gas brought in by makeup water.
– Best removed with a deaerator (removes O2 down to 7 ppb).
– Oxygen scavengers are used to react with remaining amounts of oxygen.
16
Confidential and proprietary to Garratt-Callahan Company17
Deaerating Heaters
• Mechanical Deaeration– Spray Type– Tray Type– Atomizing Type
Confidential and proprietary to Garratt-Callahan Company
Deaerator
18
Confidential and proprietary to Garratt-Callahan Company19
Pressure vs. Temperature
• For every 1 # pressure there is a loss or gain of 3o F temperature
• 5 # pressure = 227o F • At 5 # pressure or 227o F the deaerator
removes O2 down to 7 ppb• Insure that you have gages to measure
both pressure and temperature
Confidential and proprietary to Garratt-Callahan Company20
Deaerating Heaters
• Mechanical malfunction or flow control problems result in poor Oxygen removal.
• Causes of Improperly operating deaerators.– Inadequate venting.– Inadequate quantities of steam or steam pressure fluctuations.– Wide fluctuations in feed water flow.– Flow rates outside design specifications.– Malfunctioning spray nozzles, missing, plugged or broken.– Malfunctioning trays, missing, plugged or broken.
• Problems will almost always manifest as a broad temperature differential (>2°F; 1°C) between dome and storage section.
Confidential and proprietary to Garratt-Callahan Company21
Oxygen Removal - Reducing Agents and Passivating Agents.
•Reducing Agents: Include a wide variety of oxygen scavengers and passivating agents, reducing agents are electron donors.
Oxygen scavengers react with dissolved oxygen directly.
Passivating agents react with iron and copper to form a protective oxide films even in the presence of up to 5 pbb dissolved oxygen.
Confidential and proprietary to Garratt-Callahan Company22
Oxygen Removal / Passivation
Sodium Sulfite (or Bisulfite)Oxygen Scavenger:2SO3
= + O2 2SO4=
No Passivating PropertiesControl Range: Boiler Water
25-50 ppm <400 psig10-20 ppm 400-800 psig3-10 ppm 800-1250 psigNot Recommenced >1250 psig
Non-volatile, adds TDS, Can Poison Process catalysts.Not for use in attemperating water or standby in non-drainable superheaters.
Confidential and proprietary to Garratt-Callahan Company23
Oxygen Removal / Passivation
HydrazineOxygen Scavenger:N2H4 + O2 2H2O +N2
Passivating Properties:N2H4 + 6Fe2O3 4Fe3O4 + 2H2O + N2
Control Range: Boiler Water20-50 ppb Feedwater at economizer inlet.
Passivates iron and copper, Does not increase TDS, non-volatile, suspect carcinogen, and breaks down to ammonia.
Confidential and proprietary to Garratt-Callahan Company24
Oxygen Removal / Passivation
Diethylhydroxylamine (DEHA)Oxygen Scavenger:4(C2H5)2NOH + 9 O2 8 CH3COOH+ 2N2 + 6H2OPassivating Properties:2(C2H5)2NOH + 27Fe2O3 18Fe3O4 + 4CH3COOH + 3H2O + NControl Range: Boiler Water
100-150 ppb Feedwater at economizer inlet.
Very similar to hydroquinone but: generates very little ammonia, volatile, and not as thermally stable. Volatizes with steam.
Confidential and proprietary to Garratt-Callahan Company25
Oxygen Removal / Passivation
• Chemical Feed Considerations– Use stainless steel feed systems.– Use floating lids to minimize loss of products.– Use high purity, warm condensate or deaerated water
to prepare feed solutions. Never use cold water.– Limit agitation of the feed solution to 1-2 minutes– If there is no attemperation (control of superheated
steam temperature), any of the products may be fed to the deaerator storage section, just below the waterline.
– With attemperation, all sulfite products, are to be injected after attemperation takeoff.
Confidential and proprietary to Garratt-Callahan Company26
Dissolved Oxygen Analyzer
The Series μAI-9060 Dissolved Oxygen System is a state-of-the-art microprocessor-based instrument package developed specifically for use in measuring low and high concentrations of dissolved oxygen in the power, desalination, and petrochemical industry.
•Disposable DO Sensor
•Automatic Calibration
•Auto Range Switching
Confidential and proprietary to Garratt-Callahan Company
Internal Boiler Water Treatments
27
Confidential and proprietary to Garratt-Callahan Company28
Internal Boiler Water Treatment Programs
• Carbonate Cycle• Phosphate-hydroxide• Coordinated pH-phosphate• Phosphate and polymer• Chelant Treatment and/or chelant polymer• All-polymer
Confidential and proprietary to Garratt-Callahan Company29
• Chelant Treatment and/or chelant polymer– Chelant react with residual divalant metal ions
to form soluble complexes.– The complexes are removed through continues
blowdown.– Inconsistency in boiler water chemistry create an
imbalance:• Excessive chelant will result in attack on boiler
tubes. • The presents of dissolved oxygen will result in
greater deposition problems.
Internal Boiler Water Treatment Programs
Confidential and proprietary to Garratt-Callahan Company30
• All-polymer– Polymers maintain clean heat transfer surfaces in
several ways: scale inhibition, metal ion solubilization, crystal modification, and particulate dispersion.
– Polymer inhibit scale formation by disrupting the growth of deposits.
– Carboxylated polymers will form a soluble complex with feed water hardness.
– Polymers cannot be tested in process for residual, therefore inbalances in boiler water chemistry create dosing problems
Internal Boiler Water Treatment Programs
Crystal Modification
Crystal Modification
Confidential and proprietary to Garratt-Callahan Company33
• Phosphate and polymer– Phosphate precipitation.– Polymers disperse particles.– Polymers alter particle surface area and
surface charge to non scaling.– Can clean scaled boiler online.– Can be measured in process
Internal Boiler Water Treatment Programs
34
THE HIDDEN COSTS OF BOILER WATER TREATMENT
AN EVALUATION OF BOILERS IN THE LOUISIANA SUGAR INDUSTRY
James A. Cuddihy, Jr., Walter J. Simoneaux, Robert N. Falgout, and James S. Rauh
Confidential and proprietary to Garratt-Callahan Company35
Do you have Boiler Problems?
36
Facility:Date 3/17/2004
Boiler Clean Slightly Moderately Heavily Chipped Pit UnderTube Scaled Scaled Scaled Scaling Corrosion Scale
Corrosion
Boiler # Ctr Tube X Iron Oxide XDn Cmr X
Up Comr X XCtr Tube X XUp Comr X X
Dn Cmr X X
Boiler # Ctr Tube X XDn Cmr X XUp Cmr X X
Ctr Tube X XUp Cmr X XDn Cmr X X
Boiler # Ctr Tube XDn Cmr XUp Cmr X
Ctr Tube X XUp Cmr X X XDn Cmr X X
Boiler # Ctr Tube XDn Cmr X XUp Cmr X
Ctr Tube
Borescope Observation Form
37
Borescope SummaryMill Clean Slightly Moderately Heavily Chipped Pit Under
Tube Scaled Scaled Scaled Scaling Corrosion Scale
8 Mills / 43 Boilers / 222 Tubes 1/32" 1/16"+ Corrosion
A 3 4 10 2 1 3
B 6 10 12 9 3 7 7
C 3 8 16 7 15
D 3 15 1 2 3
E 1 1 18 3 1 1
F 5 12 19 2 26 4
G 2 1 7 25 7 11 20
H 9 12 5 5 6 5
Total 24 51 55 92 24 54 58
Average 10.8% 23.0% 24.8% 41.4% 10.8% 24.3% 26.1%
Confidential and proprietary to Garratt-Callahan Company38
Scale/Deposit Formation
• The primary reason for deposit and scale formation in steam generating systems is the fact that the solubility of many of the deposit forming salts decreases with an increase in temperature and concentrations. The water constituents usually responsible for these deposits are:
Calcium (Ca) Magnesium (Mg)Bicarbonate (HCO3) Iron (Fe)Sulfate (SO4) Carbonate (CO3)Silicate (SiO2) Phosphate (PO4)
Confidential and proprietary to Garratt-Callahan Company39
Light Scale (1/32”)
40
Light Scale (1/32”)
Confidential and proprietary to Garratt-Callahan Company41
Calcium Phosphate Scale Typical 1/16” Deposit
Confidential and proprietary to Garratt-Callahan Company42
Heavy Scaling
Confidential and proprietary to Garratt-Callahan Company43
Heavily Scaled
Confidential and proprietary to Garratt-Callahan Company
Heavy Scale
44
Confidential and proprietary to Garratt-Callahan Company
Heavy Scaling / Corrosion
45
Confidential and proprietary to Garratt-Callahan Company46
Chip Scale
Confidential and proprietary to Garratt-Callahan Company
Chip Scale
47
Confidential and proprietary to Garratt-Callahan Company
Pit Corrosion
48
Confidential and proprietary to Garratt-Callahan Company49
Pit Corrosion
Confidential and proprietary to Garratt-Callahan Company
Pit Corrosion
50
Confidential and proprietary to Garratt-Callahan Company51
Scale & Corrosion
Confidential and proprietary to Garratt-Callahan Company
Under Deposit Corrosion
52
Confidential and proprietary to Garratt-Callahan Company53
Under Deposit Corrosion
Confidential and proprietary to Garratt-Callahan Company
Under Deposit Corrosion
54
Confidential and proprietary to Garratt-Callahan Company55
EFFECTS OF DEPOSIT AND SCALE FORMATION
1. Heat transfer is retarded
• Boiler tube metal temperatures increase. The approximate softening temperature of boiler tube metal is about 900 0F. If heat retardation of boiler deposits causes this temperature to be reached, tube softening and rupture will occur.
• Even when deposit build-up may not be sufficient to cause tube failure, their insulating effect may still result in reduced boiler operation efficiency and energy wastage by allowing excessive heat to exit the boiler with the stack gas.
Confidential and proprietary to Garratt-Callahan Company56
2. Deposits in boilers can reduce circulation through tubes.
• This encourages further deposit formation due to the reduction of the washing effect of circulating water on solids concentrating at heat transfer surfaces.
• Since deposits are poor conductors of heat, they retard heat transfer from combustion gases.
Confidential and proprietary to Garratt-Callahan Company57
3. Deposits can also create differential corrosion cells beneath their surfaces (under scale corrosion).
• The result is localized corrosion or pitting. If such corrosion is severe, boiler metal can become thinned and weakened, resulting in ruptures due to internal boiler pressure.
Confidential and proprietary to Garratt-Callahan Company58
Fuel Value of Bagasse
• 1 mt fresh bagasse fiber – (50% moisture)
• 2.2 barrels of fuel oil – (assuming 58% boiler efficiency)
• 13,200 cu ft of natural gas – (assuming 75% boiler efficiency)
Confidential and proprietary to Garratt-Callahan Company59
Cost of Scale Formation Assumptions
• Mill grinds 10,000 TC/Day
• Bagasse = 33% of cane weight
• Fuel Prices– Fuel oil = $100.00 /barrel
• 1 ton of bagasse = 2.2 barrels of oil– Natural gas = $7.50 / mcf
• 1 ton bagasse = 13.2 mcf
Confidential and proprietary to Garratt-Callahan Company60
What is the Cost of Scale?Mill grinding 10,000 tons cane per dayTons bagsse 3,300
Scale % Fuel Tons Bagasse Fuel Oil Natural GasThickness Wasted Wasted Cost Cost
($100 x 2.2 x bwt) ($7.50 x 13.2 x bwt)
1/32" 7% 231 $50,820 $22,8691/25" 9% 297 $65,340 $29,4031/20" 11% 363 $79,860 $35,9371/16" 13% 429 $94,380 $42,4711/11" 15% 495 $108,900 $49,0051/9" 16% 528 $116,160 $52,272
Confidential and proprietary to Garratt-Callahan Company61
Additional Costs of Scale Formation
• Production Downtime• Mechanical Cleaning of Boilers• Acid Cleaning of Boilers• Tube Replacement• Increased Use of Boiler Water Chemicals
Confidential and proprietary to Garratt-Callahan Company
FIELD ANALYSIS Plant of: Date: November 19,2003AND Address:
SERVICE REPORT Attention: Copy To:
Midland Copy To:
SAMPLE FROM
pH P M OH Cl TH CaH
Fe Cu mmhos
SO3N2 H4
PO4 Mo O-P
NO2
Feedwater 12.4 60 64 20 0 .14 .02 280 2.5 0.0
Boiler #G 12.7 76 136 16 56 28 3.33 .07 2600 12.5 .10
Boiler #A 12.1 28 60 4 16 84 4.00 1.94 1200 5.0 7.9
Boiler #B12.6
80 124 36 40 92 4.10 2.25 2800 15.0 0.0
Boiler #C12.4
60 115 5 24 28 4.20 4.60 2300 12.5 0.0
Boiler #D11.8
20 28 12 16 20 3.56 4.63 660 5.0 0.6
Boiler #E11.9
24 40 8 8 68 3.06 .77 800 5.0 1.9
Boiler #F 12.5 64 76 52 16 80 4.21 2.34 2200 2.5 0.1
Control Range
9.511.5
700150300
0 0.10
.05
20003000
2040
2040
Field Analysis
Confidential and proprietary to Garratt-Callahan Company63
Boiler Tube Scale Deposit Analyses
Constituent % Dry WeightTube #1 Tube #2
Calcium Phosphate 10.7 15.0Calcium Carbonate 5.0 0.0Iron Oxide 65.0 51.8Copper II Oxide 10.0 11.2Magnesium Hydroxide 5.8 7.2
Magnetic Yes Yes
Confidential and proprietary to Garratt-Callahan Company64
Hawaiian Sugar Mill
• Produces 60,000 tons raw sugar annually• Generates electric power for HELCO utility grid
BOILER PLANT - STARTUP 1972• Babcock & Wilcox - Sterling, two drum design• Operating Pressure 1200 psi• 825 oF Superheated Steam• Boiler Rating 375,000 lbs steam per hour• Operating Load 330,000 lbs steam per hour (average)• Turbine Generator - 23,800 kW• 160 psi Extraction Steam Used For Factory Operation• Condensate Return Averages 85%• Demineralized Makeup• Cochrane Deaerator
Confidential and proprietary to Garratt-Callahan Company65
NEW DIRECTIONS IN BOILER WATER TREATMENT
• Phosphate Polymer Technology• combines internal phosphate treatment with the
latest in synthetic polymer technology• blends of polymers formulated to deal with specific
problems• enhanced thermal stability for high pressure boiler
performance• gives improved phosphate stability for hardness
control• disperses metal oxides and transports them
through the system• provides on-line removal of deposition - including
metal oxides
Confidential and proprietary to Garratt-Callahan Company66
CHEMICAL TREATMENT PROGRAM RESULTS
• Tube failure in old section of arch tubes• Boiler inspected:
• one leak found in a waterwall tube• lesser amounts of loose deposit found in boiler• significant removal of old deposit on waterwall
tubes• new (replaced) arch tube sections deposit free
Confidential and proprietary to Garratt-Callahan Company67
• Tube samples• Arch (Nose) tube and waterwall tube
Confidential and proprietary to Garratt-Callahan Company68
• Sections cut from waterwall tube• A - “bracelet” distorted• B - “hot” side• C - “cold” side
Confidential and proprietary to Garratt-Callahan Company69
• 1 inch length tube “bracelet”• Distorted to show extent of deposit
70
Original deposit condition• Waterwall tube removed
Confidential and proprietary to Garratt-Callahan Company71
• 8X magnification
• Original deposit on waterwall tube removed
Confidential and proprietary to Garratt-Callahan Company72
• Deposit condition after 12 months on Polymer Program
• Adjacent waterwall tube removed• Significant removal of old deposit
Confidential and proprietary to Garratt-Callahan Company73
• 8X magnification
• Diminished deposit on adjacent waterwall tube removed after 1 year
Confidential and proprietary to Garratt-Callahan Company74
• New Arch tube installed
• No adhering deposits
Confidential and proprietary to Garratt-Callahan Company75
• 8X magnification
• Clean arch tube after one year
Confidential and proprietary to Garratt-Callahan Company
Identifying Sugar Incursions
• Conductivity meters cannot measure sugar in boiler feed water– You measure the carryover solids (i.e.; ammonia,
non-sugars, organics)• Tracers and florescence light have not proved effective
at identifying sugar incursions at ppm.
Confidential and proprietary to Garratt-Callahan Company
Conductivity Meter Setup
1. Install automatic dump valve prior to feed water storage tank2. Place conductivity probe in condensate line prior to the dump
valve 1. False sugar positives will occur during stop and go
production as ammonia will buildup and set-off the alarm3. Set the conductivity valve set-point just above the background
reading4. When the conductivity meter sets off the alarm, the dump valve
should open automatically5. Factory personnel should test the water with Alpha-Naphthol
Test1. Find the point of contamination or if it was a false positive,
close the automatic valve.
Confidential and proprietary to Garratt-Callahan Company78
Steam Treatment: Sugar Industry
Due to the ammonia carryover from the organics in the evaporators, the residual effect maintains a high enough pH so that amines are not normally needed for steam line treatment.
Chemical Feeding Methods and Feed Points
Feed WaterTank or
Deaerator
Boiler
BottomBlowdown
Steam
Condensate
FeedwaterPump
Load
SurfaceBlowdown
12
Economizer
3 3a
4
5
Treatment Feedpoint
Sulfite 1
Hydrazine 1
Sludge Conditioner 2
Chelant 3 or 3a
Phosphate 4
Neutralizing Amine 2,4,or 5(a)
Filming Amine 5 or 3a
(a) Must be diluted with condensate of feedwater.
Confidential and proprietary to Garratt-Callahan Company80
Boiler Blowdown
• Surface blowdown– Removes dissolved solids, controls the
cycles of concentration.• Bottom blowdown
– Removes suspended solids, normally done once a shift for 5-10 seconds. Do not use to control cycles.
Confidential and proprietary to Garratt-Callahan Company81
Anti-Foams
1. Counteracts the surfactant effect of High TDS, suspended solids, oil, or other organics.
2. May be more economical than increased blowdown or additional external treatment.
3. Frequently reduce fuel consumption by permitting lower blowdown rates while producing high quality steam.
4. Will only help with normal entrainment. Will not prevent volatile (Silica) carryover.
Confidential and proprietary to Garratt-Callahan Company82
Anti-Foams
•Two types:
•Polyglycols
•Use in all boilers.
•Feed directly to boiler drum.
•Silicone
•Use in boilers with low operating pressure.
•Feed directly to boiler drum.
•Use in very small applications.
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