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BOILER WATER TREATMENT THE POLYAMINE SOLUTION. SOFTENER BOILER condenser Dosing tank Water meter uses CONDENSATE RETURN FFEED TANK BLOWDOWN RAW WATER.

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Presentation on theme: "BOILER WATER TREATMENT THE POLYAMINE SOLUTION. SOFTENER BOILER condenser Dosing tank Water meter uses CONDENSATE RETURN FFEED TANK BLOWDOWN RAW WATER."— Presentation transcript:

1 BOILER WATER TREATMENT THE POLYAMINE SOLUTION

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

3  Scaling  Corrosion  Carry over MAIN PROBLEMS

4 Including Suspended solids Organic material in solution Dissolved salts Dissolved gas Micro-organisms Sand, mud, colloidal organic material, and so on, Organic acid, vegetation rejection,… Cations : Anions : Calcium Ca 2+ Magnesium Mg 2+ Sodium Na + Potassium K + etc... Bicarbonates HCO 3 - Chlorides Cl - Sulfates SO 4 2- Nitrates NO 3 - etc... Oxygen, carbonic gas, nitrogen Algae, bacteria, fungi Raw water composition

5 unitObservations pH-Acidity or basicity Total HardnessppmCalcium+Magnesium p AlkalinityppmOH and CO3 m AlkalinityppmOH, CO3 and HCO3 Chloridesmg/LDetermination Rc T.D.S.mg/LTotal dissolved salts Conductivity  S/cmWater quality Usual water analysis

6 For P<20 bar According prEN 12953- 10 and 12952-12 standards pH> 8.5> 9.2 TH ppm CaCO3< 3< 2 Oxygen mg/L< 0,1< 0.05 Oil and greaseNo< 1 mg/L Organic mattersNoTOC < 1 mg/L 40b Feed water requirements

7 For P<20 bar General, from manufacturer According prEN 12953-10 and 12952-12 standards pH10.5 to 11.510.5 to 12 p-Alk ppm CaCO3-50 to 750 m-Alk ppm CaCO3< 1200- SiO 2 in mg/L< 200< 160 Conductivity µS/cm-< 8000 PO 4 in mg/L30 à 100< 30 Boiler water requirements

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

9 SiO 2 in steam in ppm Pressure in bar SiO 2 in boiler (mg/L) SILICA

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

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

12 3 Fe + 4 H 2 O  Fe 3 O 4 + 4 H 2 Shikorr reaction : This reaction is catalysed by dissolved oxygen. High temperature corrosion

13  BICARBONATES ARE DECOMPOSED IN CARBONATES BY HEAT WITH PRODUCTION OF CO 2  CARBONATES ARE HYDROLYSED INTO CAUSTIC SODA WITH PRODUCTION OF CO 2 THE REACTIONS :  2NaHCO 3  Na 2 CO 3 + CO 2 + H2O  Na 2 CO 3 + H 2 O  2 NaOH + CO 2 CO2 production by softened water

14 REACTION 1 : 2NaHCO 3  Na 2 CO 3 + CO 2 + H2O % decomposition time mn 100 50 100 °C 90 °C 30 60 90 120 Bicarbonate decomposition

15 REACTION 2 : Na 2 CO 3 + H 2 O  2 NaOH + CO 2 % Hydrolysis 100 50 10 20 30 40 50 P in bars Carbonate decomposition

16 PURPOSE OF BOILER WATER TREATMENT   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

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

18 MAIN OXYGEN SCAVENGERS  sulfites :  Na 2 SO 3 + ½ O 2 Na 2 SO 4  hydrazine :  N 2 H 4 + O 2 N 2 +H 2 O  tanins Oxygen scavengers

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

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

21 FILMING POLYAMINES R-  NH-  CH 2  3 -  n -NH 2   n = 0 to 7 example : octadecylamine  n = 0   R = straight carbon chain with C 12 minimum and C 18 predominant

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

23 ADSORPTION 1. Adsorption 2. Ion - ion 3. Hydrophobic bond 1 1 1 22 33

24 PSEUDO-COMPLEX FORMATION Fe CH 3 CH 2 N O H Fe H O H O H H H CH 3 CH 2 N O Fe O H O H

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 mA mV I E Auxiliary electrode (Pt) Reference electrode Rotating disc electrode (steel) Potentiostat

27 Re Rp Cd C HF R HF Re Rp Cd - jG ( .cm 2 ) R ( .cm 2 ) ReRp HF loop : film evidence IMPEDANCE DIAGRAM

28 Protection of boiler tubes  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 Boiler tube :  = 23 w/cm 2 P = 100 bars T°C = 315 °C Expansion condensation cooling Incondensable gases Emulsion water/steam 24 % Make - up : demineralized water 3 Fe + 4 H 2 O  Fe 3 O 4 + H 2 H2H2 Shikorr reaction Magnetite production : experimental procedure

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

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 in w/cm.°C THERMAL EXCHANGE

33 Film condensation Drop condensation ppm ODA  (%) 5432154321 0 1 2 3 DROP CONDENSATION

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

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


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