1 / 35

BOILER WATER TREATMENT THE POLYAMINE SOLUTION

BOILER WATER TREATMENT THE POLYAMINE SOLUTION. Water cycle in the boiler house. RAW WATER. SOFTENER. Superheater. uses. Water meter. Deaerator. FFEED TANK. condenser. BOILER. BLOWDOWN. Dosing tank. CONDENSATE RETURN. MAIN PROBLEMS. Scaling Corrosion Carry over.

shanon
Download Presentation

BOILER WATER TREATMENT THE POLYAMINE SOLUTION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. BOILER WATER TREATMENTTHE POLYAMINE SOLUTION

  2. Water cycle in the boiler house RAW WATER SOFTENER Superheater uses Water meter Deaerator FFEED TANK condenser BOILER BLOWDOWN Dosing tank CONDENSATE RETURN

  3. MAIN PROBLEMS • Scaling • Corrosion • Carry over

  4. Raw water composition Including Sand, mud, colloidal organic material, and so on, Suspended solids Organic material in solution Organic acid, vegetation rejection,… Cations : Anions : Dissolved salts Calcium Ca2+ Magnesium Mg2+ Sodium Na+ Potassium K+ etc... Bicarbonates HCO3- Chlorides Cl- Sulfates SO42- Nitrates NO3- etc... Dissolved gas Oxygen, carbonic gas, nitrogen Micro-organisms Algae, bacteria, fungi

  5. Usual water analysis

  6. Feed water requirements

  7. Boiler water requirements

  8. Scale-forming salts mg/L CaSO ,2H O 4 2 2200 (gypsum) CaSO 4 (anhydrite ) CaSO ,1/2H O 4 2 (semi-hydrate) 300 CaCO 3 100 40 60 180 °C

  9. SILICA SiO2 in steam in ppm SiO2 in boiler (mg/L) Pressure in bar

  10. Basic corrosion process Anodic reaction H O 2 Fe - 2+ OH Fe + 2 - OH - - + 2 e OH Fe(OH) 2 + + H + Cathodic reaction 2H H - + 2 e 2 2 e With dissolved oxygen : - - ® 4 e + O + 2 H O 4 OH 2 2

  11. Local oxygen corrosion Oxygen cannot reach the metal under the deposit, which creates an anodic area. O 2 O 2 O 2 - OH ++ Fe - OH - e - e - e The cathodic reaction is taking place where oxygen can reach the metal. Metal : Iron

  12. High temperature corrosion 3 Fe + 4 H2O Fe3O4 + 4 H2 Shikorr reaction : This reaction is catalysed by dissolved oxygen.

  13. CO2 production by softened water • BICARBONATES ARE DECOMPOSED IN CARBONATES BY HEAT WITH PRODUCTION OF CO2 • CARBONATES ARE HYDROLYSED INTO CAUSTIC SODA WITH PRODUCTION OF CO2 THE REACTIONS : • 2NaHCO3 Na2CO3 + CO2 + H2O • Na2CO3 + H2O  2 NaOH + CO2

  14. Bicarbonate decomposition % decomposition 100 100 °C 90 °C 50 30 60 90 120 time mn REACTION 1 :2NaHCO3Na2CO3 + CO2 + H2O

  15. Carbonate decomposition % Hydrolysis 100 50 10 20 30 40 50 P in bars REACTION 2 :Na2CO3 + H2O2 NaOH + CO2

  16. pH control of feedwater and boiler water Avoid precipitation of scaling salts: calcium carbonate, silica, iron, copper Internal protection of boiler tubes and drums Protection of condensate return lines PURPOSE OF BOILER WATER TREATMENT

  17. Phosphates Oxygen scavengers Dispersants, anti-scaling agents Neutralizing amines TRADITIONAL TREATMENT

  18. Oxygen scavengers MAIN OXYGEN SCAVENGERS • sulfites : • Na2SO3 + ½ O2 Na2SO4 • hydrazine : • N2H4 + O2 N2+H2O • tanins

  19. Toxicity: hydrazine, morpholine Corrosion of copper and copper alloys Extra salinity added: phosphates, sulfites Problems due to feedwater injection in steam MAIN DISADVANTAGES

  20. A combination of 2 main actions pH control Filming protection POLYAMINE ALTERNATIVE

  21. R-NH- CH2 3-n-NH2 n = 0 to 7 example : octadecylamine  n = 0 R = straight carbon chain with C12 minimum and C18 predominant FILMING POLYAMINES

  22. VARIOUS ACTIONS • ANTI-SCALING EFFECT • ADSORPTION : FILMING EFFECT • PSEUDO-COMPLEX FORMATION WITH METALS • DROP CONDENSATION

  23. ADSORPTION 3 3 1. Adsorption 2 2 2. Ion - ion 1 1 1 3. Hydrophobic bond

  24. PSEUDO-COMPLEXFORMATION CH3 CH3 CH2 CH2 CH2 CH2 H H N N O O H H Fe Fe H H O O O O H H Fe Fe

  25. THE POLYAMINE FILM Polyamines form a protective film on the metal surface. This film has been evidenced by means of electrochemical measurements of corrosion and particulary by electrochemical impedance diagrams.

  26. INVESTIGATION OF THE FILM EXPERIMENTAL PROCEDURE Potentiostat I mA E mV Auxiliary electrode (Pt) Reference electrode Rotating disc electrode (steel)

  27. IMPEDANCE DIAGRAM - jG (.cm2) HF loop : film evidence R (.cm2) Re Rp Cd CHF Cd Re Re RHF Rp Rp

  28. Protection of boilertubes • Polyamines stabilize the magnetite layer formation on the tubes of steam generators. • The study of the effect of POLYAMINE products on the Shikorr reaction (magnetite production) proves the efficiency of polyamines against corrosion.

  29. Magnetite production : experimental procedure Emulsion water/steam 24 % Incondensable gases H2 Expansion condensation cooling Boiler tube :  = 23 w/cm2 P = 100 bars T°C = 315 °C Make - up : demineralized water 3 Fe + 4 H2O  Fe3O4 + H2 Shikorr reaction

  30. Stability of the magnetite layer H2 as vpm (volume per million) Magnetite production POLYAMINE injection 10 2 vpm during 72 hours 2 time

  31. HEAT EXCHANGE • The polyamine film formed on metal surfaces does not affect the thermal exchange. • Presence of polyamines increases the yield of condensers.

  32. THERMAL EXCHANGE  in w/cm.°C

  33. DROP CONDENSATION Dh (%) 5 4 3 2 1 Film condensation ppm ODA Drop condensation 0 1 2 3

  34. Toxicity of hydrazine: LD 50 = 60 mg / kg of weight Carcinogenic Inocuity of the polyamine: LD 50 > 2000 mg / kg Non carcinogenic Toxicity vs inocuity

  35. Efficiency Simplicity Hydrazine free Non toxic Reduction of blowdown Improvement of condenser yield Cost-effective CONCLUSIONS

More Related