1. BOILER WATER TREATMENT THE 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 Suspended solids
Sand, mud, colloidal organic material, and so on,
Organic material in solution
Organic acid, vegetation rejection,…
Dissolved salts
Cations :
Anions :
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 unit Observations pH - Acidity or basicity
Total Hardness
ppm
Calcium+Magnesium
p Alkalinity
OH and CO3
m Alkalinity
OH, CO3 and HCO3
Chlorides
mg/L
Determination Rc
T.D.S.
Total dissolved salts
Conductivity
mS/cm
Water quality

6. Feed water requirements
For P<20 bar
According prEN and
standards pH
> 8.5
> 9.2
TH ppm CaCO3
< 3
< 2
Oxygen mg/L
< 0,1
< 0.05
Oil and grease No
< 1 mg/L
Organic matters
TOC < 1 mg/L
< 0,2 if P>40b

7. Boiler water requirements
For P<20 bar
General, from
manufacturer
According prEN and
standards pH
10.5 to 11.5
10.5 to 12
p-Alk ppm CaCO3 -
50 to 750
m-Alk ppm CaCO3
< 1200
SiO2 in mg/L
< 200
< 160
Conductivity µS/cm
< 8000
PO4 in mg/L
30 à 100
< 30

8. Scale-forming salts mg/L CaSO ,2H O 2200 (gypsum) CaSO (anhydrite )4 2
(gypsum)
CaSO 4
(anhydrite )
CaSO
,1/2H O 4 2
(semi-hydrate)
300
CaCO 3
100 °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 Fe 2+
+ 2 OH - OH -
+ 2 e - OH -
Fe(OH) 2 + H +
Cathodic reaction - + 2H +
2 e H 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 O 2 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
100
100 °C
90 °C 50
time mn
REACTION 1 : 2NaHCO3  Na2CO3 + CO2 + H2O

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

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

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. R-NH- CH2 3-n-NH2 FILMING POLYAMINES n = 0 to 7
example : octadecylamine  n = 0
R = straight carbon chain
with C12 minimum
and C18 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 3 3 2 2 1 1

24. PSEUDO-COMPLEX FORMATION
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 mV E
Auxiliary
electrode
(Pt)
Reference
electrode
Rotating disc
electrode (steel)

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

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. Emulsion water/steam 24 %
Magnetite production :
experimental procedure
Emulsion water/steam 24 % H2
Incondensable gases
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 (%) Film condensation ppm ODA Drop condensation 54 3 2 1
Film condensation
ppm ODA
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