Special Stainless Steels for FGC and CCS

Transcription

1 Special Stainless Steels for FGC and CCS ATI Milan, 13/4/2011 Dr Pascale Sotto Vangeli, Avesta Research Centre Eng. Jim Augustsson, Special Plate

2 Chemical composition and properties Typical chemical composition weight % Outokumpu EN ASTM Cr Ni Mo N PRE* R p0.2 ** LDX S *** Lean Duplex LDX S Lean Duplex S Duplex S Duplex SAF S Super Duplex S Super Duplex L Austenitic L Austenitic L Austenitic 904L N Austenitic 254 SMO S Super Austenitic 654 SMO S Super Austenitic N Super Austenitic S * PRE = %Cr + 3.3x%Mo + 16x%N ** [MPa] Hot rolled plate, min values at 20 o C according to EN ***Not yet in EN 10088, Rp0.2 according to ASTM A240 2 April 13, 2011 Pascale Sotto Vangeli Mn Super Austenitic

3 Corrosion indicators: PRE and CPT PRE Pitting Resistance Equivalent CPT Critical Pitting Temperature Corrosion Resistance, CPT typical Outokumpu 654 SMO has the highest PRE value (56). It is completely resistant to corrosion in standard CPT tests. duplex austenitic 4307 LDX LDX L SMO SMO PRE April 13, 2011 Pascale Sotto Vangeli

4 Characteristics of Outokumpu 654 SMO Outstanding resistance to pitting, crevice and uniform corrosion Extremely high resistance to stress corrosion cracking High erosion resistance Excellent formability Good ductility and toughness Almost twice the strength of common austenitic stainless steels Price advantage alternative to Ni-base alloys Price stablility compared to Ni-based alloys Excellent choice when superior corrosion resistance and high mechanical properties are required 4 April 13, 2011 Pascale Sotto Vangeli

5 Corrosion indicators: CCT tests Crevice corrosion: laboratory and field tests to compare Outokumpu 654 SMO at least as resistant as C-276 to crevice corrosion in oxidizing, highchloride solutions 5 April 13, 2011 Pascale Sotto Vangeli

6 Duplex and austenitic grades Yield Strength R p0.2 [MPa] 750 duplex 500 LDX LDX 2404 TM SMO austenitic L 254SMO C-276 Corrosion resistance 6 April 13, 2011 Pascale Sotto Vangeli

7 Structural efficiency utilize strength of duplex grades Weigth saving potential 60% 50% 40% LDX 2101 weigth saving potential to 304L 2205 weigth saving potential to 316L 30% 20% 10% 0% Cylinder with internal pressure Hollow section loaded in bending Plate loaded in bending Local buckling 7 April 13, 2011 Pascale Sotto Vangeli

8 Case: Duplex as substitute for austenitic in storage tank Benefits: Weight reduction Improved cost efficiency Material cost Initial investment cost Maintenance cost Life Cycle Costing Increased service life ton LDX ton [m] Duplex potential weight saving: ~30% April 13, 2011 Pascale Sotto Vangeli [mm]

9 9 April 13, 2011 Pascale Sotto Vangeli Flue Gas Desulfurization System

10 Economical concept in absorbers Increasing Corrosion Resistance 317LMN 904L 2205 SAF SMO SMO adjust transitions according to operating conditions 10 April 13, 2011 Pascale Sotto Vangeli

11 Guideline for material selection in FGD applications Different colours represent different operating conditions in term of acidity and Cl-/F- concentration. Based on long-term industrial experience, field and laboratory testing. Other factors such as design, processing of material, workmanship, etc. will also have an influence on the materials behaviour.

12 La Spezia, Italy 2001 chloride - max ppm Cl - in quencher recycle - max ppm Cl - in absorber recycle ppm in demister area (during demister cleaning with sea water) acidity: - quencher ph 3,5 5 / 4,5 - absorber ph 5 6,4 / 6 temperature: 5 50 / 42,5 C flue gas entry: / alloy C-276 gas outlet: wall plates / 317L demister area: demister support structure and wall plates / UNS absorber recycle: box ring girder top side, shell plates, spray pipes / UNS collection bowle area: collection bowl, discharge pipe, bowl plates, box ring girder bottom side / UNS quencher recycle: shell plates, floor plates, spray pipes and other internals (sieves, sparger pipes,...) / UNS April 13, 2011 Pascale Sotto Vangeli

13 FGC applications Spray system in Abb.: Fisia Babcock Absorber module in 2205 Abb.: Babcock & Wilcox 13 April 13, 2011 Pascale Sotto Vangeli

14 CCS - stainless opportunities Flue gas cleaning austenitic & duplex Solvent separation systems Amine standard or lean duplex Cryogenic applications 304L, 201LN Tubes & pipes high pressure piping, PSA duplex duplex Compressors part?? Pipe High lines temperature material Burners, High temperature casing, cyclones, material Burners, supports, casing, tube protection cyclones, 153 MA, 253 MA, 304H, 321H supports, Standard tube grades protection 153 MA, 253 MA, 304H, 321H Internals, Standard heat grades exchangers, piping Internals, Clad material heat exchangers, piping standard cladding Clad material solutions standard or duplex Solid or cladding solutions standard or duplex 14 April 13, 2011 Pascale Sotto Vangeli

15 Cooperations Vattenfall, Sweden - Germany Siemens, USA Doosan Power Systems, UK Alstom Power, Germany Hitachi Power Europe, Germany 15 April 13, 2011 Pascale Sotto Vangeli

16 Conclusions FGC Environments in wet cleaning systems are hard to predict and can be very aggressive. Need of corrosion resistant grades. There are large variations in environments between different plants and different locations within plants. Material selection has to be done for each plant/application individually. The main risks for stainless steel are pitting and crevice corrosion. The following ranking applies: 316L < 317L~904L~2205 < 2507~254SMO < 4565 < 654SMO 16 April 13, 2011 Pascale Sotto Vangeli

17 Conclusions CCS By choosing the correct stainless steel grade, it is possible to meet a wide range of demands on corrosion resistance. Need to test in the demanding environments to select the most suitable grade. Utilize the strength of the duplex in big amine towers. Tools on 17 April 13, 2011 Pascale Sotto Vangeli

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