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transcript
POLYAMINES: STEAM SYSTEM TREATMENT OF THE 21ST CENTURYAQUATECH Industrial User Experience
© Roy van Lier, November 6, 2015
No. 1
GELEEN SITE
No. 2
PECULARITIES OF INDUSTRIAL STEAM GENERATION
Boiler design and operation dictated by (petro)chemical process conditions
Very high heat flux steam generators
Minimalistic design, little monitoring
Multiple individual steam systems with centralized treatment
High make-up water demands
Reuse of potentially contaminated condensates
Condensation of steam both at low and high temperatures
No preventive chemical cleaning
Long turnaround intervals
CRACKER HIGH PRESSURESTEAM SYSTEM
No. 4
INTRODUCTION
Anon., “SHG Double Tube Heat Transfer Line Exchangers in Ethylene Plants”, Schmidt’sche Heissdampf-Gesellschaft mbH
No. 5
TRANSFER LINE EXCHANGERS –EXAMPLES OF ENGINEERING ASPECTS
Tunnel flow design: Double tube design:
Anon., “SHG Double Tube Heat Transfer Line Exchangers in Ethylene Plants”, Schmidt’scheHeissdampf-Gesellschaft mbH
Anon., “Tunnelflow Transfer Line Exchangers(Quench Coolers) for Ethylene CrackingFurnaces”, Deutsche Babcock-Borsig AG
No. 6
TRANSFER LINE EXCHANGERS –SUSCEPTIBILITY TO DAMAGE DUE TO FOULING
“HEAT FLUX x FOULING = BOILER TUBE FAILURES”
No. 7
MAGNETITE – APPEARANCE, MORPHOLOGY
Microscopic:
Macroscopic:
current steel surface
original steel surface“dense” topotactic
layer
porous epitacticlayer
CONVENTIONALCYCLE TREATMENT
No. 9
“SOLID” ALKALIS FOR BOILER WATER TREATMENT
Caustic soda, NaOH
TSP, TriSodium Phosphate, Na3PO4
A major drawback of these alkalizing agents is that they may cause boiler damage!
Caustic Gouging Caustic Stress Corrosion Cracking Phosphate Wastage
No. 10
Ammonia, the simplest amine
Classic “engineered” amines, including
• cyclohexylamine
• ethanolamine (MEA)
• 2-(diethylamino)ethanol (DEAE)
• 3-methoxypropylamine (MOPA)
• morpholine
NEUTRALIZING AMINES FOR ALL-VOLATILE TREATMENT (AVT)
Selection on the basis of the “3Ds”:
1. Dissociation (basicity)2. Distribution (volatility)3. Degradation (thermal stability)
No. 11
MORPHOLINE (1)
Geleen cracker HP steam system was treated using ammonia/morpholine ever since startup
Conventional measures failed to resolve iron oxide deposition and corrosion problems
Compounding factor:
thermochemical instabilityof morpholine
J. Savelkoul et al., PowerPlant Chemistry, 2001 3 (6), p. 326-330
No. 12
MORPHOLINE (2)
FCC = First Condensate CorrosionFAC = Flow-Accelerated Corrosion
Steam/Cond. Corrosion
Phenomena
FeedwaterCorrosion
Phenomena
MagnetiteTransport/ Deposition
Boiler Tube Failure
Morpholine Organic Acids
FAC
FCC FAC
erroneouspH corrections
POLYAMINES – INTEGRALCYCLE TREATMENT
No. 14
FILM FORMING AMINES –THE INTEGRAL TREATMENT APPROACH
For certain steam systems it is impossible to satisfactorily solve fouling and corrosion issues using conventional chemistry
and
Some plants just cannot meet the stringent “power plant inspired” water quality guidelineslaid down by technical institutes like VGB (Germany) and EPRI (USA)
This reality has prompted us to look for an alternative treatment methodbased on the philosophy that it is more important to maintain a clean boiler system
than to remove the last traces of impurities from the water
Utilization of combined “cleaning effect” and“steel/water interface alkalinity” provided by filming amines
of the oligoalkylamino fatty amine family,in particular N-oleyl-1,3-propanediamine
No. 15
FILM FORMING AMINES
G. Bohnsack, VGB Kraftwerkstechnik, 77 (10) 1997, p. 841-847
No. 16
TREATMENT PROGRAM TOLERANCE TO IMPURITIESWITH RESPECT TO BOILER TUBE FAILURES
Table courtesy of A. Bursik:
BFW BW Tolerance towards Impurities
AVT(R) no ����
AVT(O) no ��������
OT NaOH ����������������
AVT(R) NaOH ��������������������
AVT(O) NaOH ����������������������������
AVT(R) Na3PO4
+ 1 mg · L–1 NaOH
����������������������������������������������������
AVT(O) Na3PO4
+ 1 mg · L–1 NaOH
����������������������������������������������������������������������������
Amine Polyamine, Polyacrylate, NaOH
����������������������������������������������������������������������������
CRACKER POLYAMINE APPLICATION
No. 18
INTRODUCTION
Block diagram of the Geleen cracker’s steam system:
Conversion to polyamines was done end 2005
To the best of our knowledge no other cracker in the world uses polyamines (yet)
R. van Lier et al., PowerPlant Chemistry, 10 (12) 2008, p. 696-707
No. 19
SUMMARY OF RESULTS
Results after 10 years:
• Thinner magnetite layers• Improvement of water/steam quality• Exceptionally clean turbines• Water & energy savings due to
blowdown reduction• Longer interval between
cation exchanger regenerations• Less analyses
• Unexpected (fouling) incidents• Supplier issues• Product stability issues• Analytical issues
No. 20
EXAMPLES OF POSITIVE RESULTS
Lowering of (18 bar export) steam acid conductivity to ~0.3 µS/cm
Exceptionally clean and mechanically sound turbines
Most importantly: stable operation, no major upsets, no (TLE) damage
No. 21
EXAMPLES OF NEGATIVE RESULTS
Accumulation of sticky, messy iron oxide deposits in low velocity zones, specifically in early days of polyamine program
CONCLUSIONS ANDFINAL REMARKS
No. 23
CONCLUSIONS AND FINAL REMARKS
A cracker high pressure steam system can be safely, reliably and cost effectively treatedusing polyamines
Time has come for VGB, EPRI, KEMA etc. to accept polyamine treatment as a valuablealternative treatment option
“We can't solve problems by using the same kind of thinkingwe used when we created them” (Einstein)
The main hurdle for the furthering of polyamine chemistry is the elevated acid conductivity of steam (condensate) it brings about in relation to turbine warranty