Download as PDF, PPTX
![O-
O-
Phosphonate
P = O
Poly (isopropenyl phosphonic acid)
PIPPA
O P
C
CH3
OH
X
O-
CH2
=
R
HEDP
P
- O
O
C P
CH3
OH
O
O -
- O
O -
=
=
Polyethylene glycol allyl ether (PEGAE)
CH2 CH
C = O
O- H+
CH2 CH
CH2
O [CH2 CH2 O]m
H
n
Typical Polymer Structures](https://image.slidesharecdn.com/boilerbestpractices1639939606-220808031754-e4070bb2/85/Boiler_Best_Practices_1639939606-pdf-34-320.jpg)
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Boiler_Best_Practices_1639939606.pdf
- 1. Boiler Water BestPractises Boiler Water Best Practises
- 2.
- 3. Why is EffectiveInternal Boiler Water Treatment Necessary ?
- 4. Effective Internal BoilerWater Treatment Controls • Deposition • Corrosion • Carryover and
- 5. Enhances System Reliability andEfficiency • Avoids unscheduled shutdowns • Helps ensure uninterrupted production • Reduces maintenance costs • Reduces operating costs
- 6. What Operating Costsare Associated with Boiler Operation ?
- 7. Boiler Operating Costs •Fuel - Gas, Oil, Coal • Water - Influent and Effluent • Regenerants - Salt, Acid, Caustic • Water Treatment
- 8. • Fuel -Gas, Oil, Coal • Water - Influent and Effluent • Regenerants - Salt, Acid, Caustic • Water Treatment Boiler Operating Costs
- 9. • Need tominimise all operating costs Reducing boiler water blowdown gives water, energy and chemical savings • Need to maximise efficiency Maintain clean heat transfer surfaces Heat recovery systems Boiler Operating Costs
- 10. Effective Internal BoilerWater Treatment Controls • Deposition
- 11. Boiler Water DepositControl • Hardness salts • Calcium • Magnesium • Metal oxides • Iron • Copper
- 12. Comparison of HeatTransfer Surfaces With and Without Deposits Fireside Waterside Fireside Waterside Metal Metal Scale Without deposits With deposits 600°F 500°F 500°F 800°F and above
- 13. Energy Loss fromScale Deposits (from Energy Conservation Programme Guide for Industry & Commerce) 1 64 1 32 3 64 1 16 5 64 3 32 0 Scale Thickness, inches or mm Energy Loss % 8 7 6 5 4 3 2 1 I r o n & S i l i c a S c a l e High Iron Content Scale "Normal" Calcium Carbonate Scale 0.4 mm 0.8 mm 1.2 mm 1.6 mm 2.0 mm 2.4 mm
- 14.
- 15. Boiler Water DepositControl • Removal of impurities • Pretreatment plant • Chemical treatment • Controlled blowdown
- 16. Effective Internal Boiler WaterTreatment Controls • Deposition • Corrosion
- 17. Boiler Water CorrosionControl • Oxygen pitting • Caustic corrosion • Embrittlement or gouging • Acidic attack
- 18. Oxygen Corrosion -Pitting
- 20.
- 21.
- 22. Effective Internal Boiler WaterTreatment Controls • Deposition • Corrosion • Carryover
- 23. Control of BoilerWater Carryover • Effective mechanical steam separation • Proper control of boiler water chemistry • Antifoam, as needed • Avoid major contaminant ingress • Proper boiler operating practices
- 24. What Types of InternalBoiler Water Treatments are Available ?
- 25. Internal Treatment Programmes General Classifications •Precipitating • Solubilising • Combination
- 26. • Phosphate/Polymer • Phosphonate/Polymer •Chelant/Polymer • Phosphate/Chelant/Polymer • All Polymer • Coordinated pH/Phosphate/Polymer • All Volatile Treatment (AVT) Internal Treatment Programmes
- 27. Boiler Water Polymers areCrucial to the Success of any Internal Treatment Programme
- 28. How do BoilerWater Polymers Function ?
- 29. Boiler Water Polymers The mechanismsby which boiler water polymers function are • Complexation / Solubilisation • Crystal modification • Dispersion
- 30. Calcium phosphate, magnesium silicate crystalsformed in boiler water without dispersant
- 31. Calcium phosphate, magnesium silicate crystalsformed in boiler water in the presence of a sulphonated polymer
- 32. Variables Affecting Polymer Performance •Functional group • carboxylated (SCP/SCCP) • sulfonated (SSP) • phosphorylated (HTP) • Polymer backbone • Molecular weight
- 33. CH3 O- Polymethacrylate X C CH2 C=O CH O- CH2 Polyacrylate C =O X CH2 OH CH Acrylate-Acrylamide Copolymer CH2 NH2 CH X C = O C = O CH2 SO3 - CH Sulfonated Styrene-Maleic Anhydride Copolymer CH CH C X Y C = O O O = Typical Polymer Structures
- 34. O- O- Phosphonate P = O Poly(isopropenyl phosphonic acid) PIPPA O P C CH3 OH X O- CH2 = R HEDP P - O O C P CH3 OH O O - - O O - = = Polyethylene glycol allyl ether (PEGAE) CH2 CH C = O O- H+ CH2 CH CH2 O [CH2 CH2 O]m H n Typical Polymer Structures
- 35. Polymer Performance vs Molecular Weight PolymerMolecular Weight Deposition
- 36. Programme Selection Considerations • Boilerpressure, design • Pre-treatment plant type • Feedwater quality • Hot well, deaerator type • Steam turbine • Control capabilities
- 37. Chemical Factors • TotalDissolved Solids (TDS) • Alkalinity • Silica • Suspended Solids
- 38. ASME Boiler FeedwaterQuality Guidelines for Modern Industrial Water-Tube Boilers • Drum Pressure • (kg/cm²) • 0 - 21 • 22 - 31 • 32 - 42 • 43 - 52 • 53 - 63 • 64 - 70 • 71 - 105 Iron (ppm Fe) 0.10 0.05 0.03 0.025 0.02 0.02 0.01 Copper (ppm Cu) 0.05 0.025 0.02 0.02 0.015 0.015 0.01 Hardness (ppm CaCO3) 0.30 0.30 0.20 0.20 0.10 0.05 0.0
- 39.
- 40. Phosphate/Polymer Treatment • Reactions: •Ca + PO4 + OH Ca(OH)PO4 • Calcium Phosphate Hydroxide Hydroxyapatite • • Mg + SiO3 + OH Mg(OH)SiO3 • Magnesium Silica Hydroxide Serpentine
- 41. Phosphate/Polymer Treatment Characteristics • Hardnesscontrolled by precipitation • Polymers used to control hardness sludge and metal oxides • Phosphate residual used for programme control • Hydroxide alkalinity required (pH : 10.5 - 12)
- 42. Phosphate/Polymer Treatment Boiler Control Parameters •Phosphate residual as PO4 depending on hardness in the feedwater • usually associated with boiler pressure • and environmental legislation • M alkalinity of 700 ppm as CaCO3 (25 % of TDS) • Polymer : min 360 ppm as SP8100 • Still the most used method for treating low pressure boilers
- 43. Phosphate/Polymer Treatment • Disadvantages • Isa precipitation programme (some deposition is normal) • Higher blowdown rates may be required Advantages • Tolerates a wide range of feedwater hardness • Non corrosive treatment • Suitable for low to medium pressure systems • Easy operator control
- 44. Internal Treatment Programmes •Phosphate/Polymer • Phosphonate/Polymer
- 45. Phosphonate/Polymer Characteristics • Organic phosphordonors combined with three synergistic polymers • Complexes hardness, iron and copper ions in BFW • Disperses/solubilises contaminants in boiler minimising sludge formation
- 46. Phosphonate/Polymer – 200 -300 ppm in blowdown – (BFW hardness + tot Fe) max 1 ppm for 300 ppm in boiler – filtered tot. PO4 min 6 ppm in BD – Other : • conductivity • SiO2 • M-alk a) Solubilising Boiler Control Parameters
- 47. b) Precipitating • Phosphateresidual as PO4 depending on hardness in the feedwater • M alkalinity of 700 ppm as CaCO3 (25 % of TDS) Phosphonate/Polymer Boiler Control Parameters
- 48. Internal Treatment Programmes • Phosphate/Polymer •Phosphonate/Polymer • Chelant/Polymer
- 49. Chelant/Polymer Treatment • Common ChelatingAgents • EDTA • NTA
- 50. Chemical Structure of EDTA -OOC - CH2 - OOC - CH2 N - C - C - N H CH2 - COO - CH2 - COO - H H H
- 51.
- 52. Chelant/Polymer Treatment Characteristics • Aresolubilising treatments • Chelant complexes hardness and soluble iron / copper • Polymers used to enhance metal oxide control • Must be fed to the feedwater line
- 53. Chelant/Polymer Treatment • Disadvantages •Requires intensive operator control • Potentially corrosive if misapplied Advantages • Solubilising treatment • Effective on hardness and soluble iron • Allow reduced blowdown • Increased reliability and efficiency • Suitable for low to medium pressure systems
- 54. Internal Treatment Programmes • Phosphate/Polymer •Phosphonate/Polymer • Chelant/Polymer • Phosphate/Chelant/Polymer
- 55. Chelant/Phosphate/Polymer Treatment Characteristics • Utilises EDTAchelant (partial chelation) • Primarily a solubilising programme • Phosphate provides back-up upset protection • Residual phosphate test used as programme control • Polymers used to control metal oxides and other precipitates
- 56. Chelant/Phosphate/Polymer Treatment • Disadvantages • Someprecipitation is possible • Potentially corrosive if misapplied Advantages • Primarily a solubilising treatment • Effective on hardness and iron • May allow reduced blowdown • Increased reliability and efficiency • Easy and accurate control test • Tolerates a wide range of feedwater hardness • Suitable for low to medium pressure systems
- 57. Internal Treatment Programmes • Phosphate/Polymer •Chelant/Polymer • Phosphate/Chelant/Polymer • All Polymer
- 58. All Polymer Treatment Characteristics •Certain polymers can be effective complexing agents • Principle mechanism is complexation of soluble impurities • Secondary mechanism is dispersion of particulates • Fed to the boiler feedwater
- 59. Limitations of PolyacrylateBased All Polymer Programmes • Low tolerance to feedwater quality upsets • Potential for calcium polyacrylate deposition • Releases ammonia • Economiser iron pick-up • Precise testing for polymers is difficult
- 60. Internal Treatment Programmes • Phosphate/Polymer •Phosphonate/Polymer • Chelant/Polymer • Phosphate/Chelant/Polymer • All Polymer/OptiSperse AP
- 61. What is OptiSperseAP ? • A new, revolutionary programme using patented co-polymer technology • A stand-alone all polymer / all organic boiler internal treatment programme which provides superior control over hardness and iron deposition
- 62. OptiSPerse AP Treatmentvs. Traditional All Polymer • Traditional All Polymer Programme • Generates ammonia • Forms calcium-polymer deposits with BFW hardness excursions or underfeed • Overfeed may cause foaming • Corrosive to economiser surfaces • Must be fed downstream of copper alloys • OptiSperse AP Programme • No ammonia generated • No treatment related deposition • No steam purity problems • Not corrosive to preboiler circuit • May be fed ahead of copper alloys in BFW
- 63. Research Boiler StudiesUnder Fouling Conditions Test Conditions 900 psig (63 kg/cm2) All-polymer Programme Ca/Mg/Fe present TRADITIONAL ALL-POLYMER OPTISPERSE AP 0 1 2 3 4 5 POLYMER/HARDNESS RATIO DWD
- 64. Research Boiler Studies UnderPotential Fouling Conditions (Equal Polymer Actives) 300 psig (21 kg/cm2) 600 psig (42 kg/cm2) 900 psig (63 kg/cm2) Deposit Weight Density OPTISPERSE AP Traditional All-Polymer
- 65. Internal Treatment Programmes • Phosphate/Polymer •Phosphonate/Polymer • Chelant/Polymer • Phosphate/Chelant/Polymer • All Polymer • Coordinated pH/Phosphate/Polymer
- 66. Coordinated pH/Phosphate Polymer Treatment Characteristics •Primarily for high purity/high pressure systems • Mainly a corrosion control programme • Phosphate used to control pH and neutralise excess caustic • Polymers used to control deposition
- 67. Corrosion of MildSteel vs. pH 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Safe Range Relative Corrosive Attack 8.5 pH 12.7 pH
- 68. Caustic Concentration Mechanism Magnetite NaOH Steam Out NaOH BoilerWater in Fe3O4 Porous Deposit NaOH NaOH NaOH NaOH
- 69. Boiler water in steam escapes porous deposit magnetite Na+ HPO4 2- Na+ Na+ Na+ Na+ Prevention HPO4 2 - HPO4 2 - HPO4 2 - HPO4 2 -
- 70. Minimising Caustic Concentration andCorrosion using Phosphate NaOH + Na2HPO4 Na3PO4 + H2O Caustic Soda Disodium Phosphate Trisodium Phosphate Water
- 71. Co-ordinated Congruent Phosphate/pH ControlChart 2.6:1 Na/PO4 8.2 8.4 8.6 8.8 9.0 9.2 9.4 9.6 9.8 10.0 10.2 10.4 10.6 10.8 10 2 3 4 5 6 7 8 1 15 20 30 40 50 60 Ortho-phosphate, as PO4 mg/l "Free" Caustic Region Maximum Boundary 3.0:1 Na/PO4 Molar Ratio Control Boundary 2.2:1 Na/PO4 Molar Ratio "Captive" Alkalinity Region 2.7:1 Na/PO4 2.8:1 Na/PO4 pH Vector Control Diagram T r i - S o d i u m P h o s p h a t e Caustic M ono-Sodium Phosphate Blowdown Di-Sodium Phosphate
- 72. Internal Treatment Programmes • Phosphate/Polymer •Phosphonate/Polymer • Chelant/Polymer • Phosphate/Chelant/Polymer • All Polymer • Coordinated pH/Phosphate/Polymer OptiSperse HTP
- 73. Characteristics of HTP-2 •A unique new phosphorylated boiler polymer • Particularly effective on iron • Demonstrated clean-up ability • Designed for high purity/high cycles systems • Suitable for use up to 125 kg/cm²
- 74. HTP-2 Polymer Structure OP C CH3 OH X O- CH2 = Poly (isopropenyl phosphonic acid) . . . PIPPA
- 75. Internal Treatment Programmes • Phosphate/Polymer- OptiSperse PO, OptiGuard MCP • Phosphonate/Polymer - OptiSperse PQ • Chelant/Polymer - OptiSperse CL • Phosphate/Chelant/Polymer - OptiSperse CP • All Polymer - OptiSperse AP, OptiGuard MCA • Coordinated pH/Phosphate/Polymer - OptiSperse HTP • All Volatile Treatment (AVT)