Weld Overlay High Temperature Corrosion in Biomass ... · PDF fileWeld Overlay High...
Transcript of Weld Overlay High Temperature Corrosion in Biomass ... · PDF fileWeld Overlay High...
www.azz.com/wsi-europe 1
Weld Overlay
High Temperature Corrosion in Biomass Combustion
World Bioenergy Conference
Hans Bengtsson
2014-06-05
www.azz.com/wsi-europe 2
AZZ® at a Glance
AZZ® incorporated
HQ: Fort Worth Texas, USA
Employees: 3,400
Locations: 49
Market cap: $ 1,05bn
AZZ is listed on the NYSE (AZZ)
Markets: Refining, Nuclear, Fossil power, Waste to
Energy, Chemical/Industrial processing, Pulp/Paper,
Steel manufacturing processing
• Steel manufacturingWSI
Innovative maintenance through automatic
weld repair solutions
• PQR/WPS development (600+ procedures)
• Welding plans (1500+) / repair plans
• 2013: 800 scopes executed in 35 countries
WSI Global Footprint
Galvanizing
Electrical & Industrial
WSI/SMS
www.azz.com/wsi-europe 3
Our capabilities
WSI is a specialized global service company offering innovative maintenance through
Automated Weld Repair Solutions that extend the lifetime and maximize the value of
our customers' assets in the Energy Industry
Qualified QA programs• Requirements/technical review
• WPS/PQR
• Craft qualification certificates
• Testing/inspection procedures and material inspection reports
Non-Nuclear Quality Assurance Programs• NBIC certified R, S, U, U2
• EN ISO 3834 – 3
• ASME Section I and VIII, Div. 1 & 2
• Ad 2000 Merkblatt HPO, TRD 201
Safety• Automation that allows safety performance
• PPE to reduce risk and fatigue
• Highly skilled and qualified craft and qualified HSE managers
• Human performance-based prevention
• Safety equipment and plans
Example quality
Certificate
Ad 2000 Merkblatt
HPO, TRD 201
www.azz.com/wsi-europe 4
Our products
Lakeside UK - Boiler, October 2013
UT Readings – Ultrasone Testing
Welding engineers involved
in every step of our work
Shop products - fabrication of front and floor tube panel
using UNIFUSE® 625/CS overlay tubes and membrane bar
Field services – on site weld overlay
Tie-in finishing after replacement
Field Services• Waterwall overlay, re-overlay
• Tie in
Shop fabrication• Panel
• Tubes
• superheater, evaporator, etc
Inspection and maintenance program:• QA Inspectors
• Welding engineer
www.azz.com/wsi-europe 5
Biomass challenges
Biomass as collected/harvested and dried
Semi-processed biomass (pellets, etc)
The ready availability of waste biomass in many countries differs from one to other:
Straw
Differnt wood sources
Harvested product – depending
on the area: pine, eucaliptus,
olive, rice, etc
Corrosion on biomass facilities has
turned into a real challenge. Every
plant shows different behaviour:
• Operational parameters
• Waste composition
• Relative new technology
Need to establish a relationship
between: manufacturers, end
user, maintenance providers, R&D Black liqour or mixed fuel also
containing municipal waste, industrial
waste, animal residues, sewage, etc
www.azz.com/wsi-europe 6
Biomass fuel and boiler
Biomass fuel
• Chemical composition: agricultural wastes typically contain more alkali metals and
chlorine than conventional fuels
• Fuel characteristic: chips, rejected wood, straw, or fuel characteristic in general may
cause ashes leading to erosion
• Fuel procedence: harvested fuel as in pine and eucaliptus brings also sand, leading
to erosion
Corrosion Erosion
Every plant may have a dominant
wear phenomena, depending on
fuel, operational paramenters, etc
Chlorine causing accelerated
corrosion and fouling
www.azz.com/wsi-europe 7
Corrosion problem at waterwall and superheater
1) Chlorine, potassium, sodium and sulfur ashes deposited on pressure boundary
bringing heat steam to higher temperature levels
2) Surrounding corrosive flue gases
3) Operational temperature factors: depending on the temperature:
- Alkali salts molten on tube surface reacting with protective oxides
- Alkali salts forming low melting temp. eutectics with other ash materials
(ex. KCl is more corrosive than NaCl and has a lower melting temperature)
Operational parameter:
Reduction of steam and
metal temperatures
Fuel characteristics:
Reduce chlorine content
by mixing or using
additives
Improve metallurgy on
evaporator and SH tubes,
heat exchangers and hot
gas paths
Metal alloy for corrosion protection has to be commercial available, economically
efficient and easy to apply
www.azz.com/wsi-europe 8
Protection for Waterwall
Welding overlay with alloy 625 ON-SITE
Welding overlay with alloy 625 on shop panels for replacement + on site TIE-IN
Shop panel protection on-site installation + tie-in
On site weld overlay on both
CS or on old 625 is possible
Old fatigued alloy 625 grinded off until smooth
surface, then automatic weld overlay
Panel replacement when tube
thickness is too low.
Replacement panels protected
www.azz.com/wsi-europe 9
Improve metallurgy on pressure parts shop and field both:
• Preventive
• Currative
sCases from boilers in Sweden
www.azz.com/wsi-europe 10
Showcase- MW Power- Vattenfall- Jordbro plant
• MW Power-Vattenfall Jordbro Biomass power station
• Alloy 625 panel weld overlay field (~250m²) and shop (~80m²)
• Project execution in September 2012
Main dimensional boiler data - NEW BUILD on-line June 2010
• Fuel: waste wood and forest residue
• 63MWth / 82 bar / +473 °C
• Boiler efficiency > 90%; Particulate emissions < 15mg/Nm3
• NOx-emissions < 70 mg/MJ
• Fuel need: 20.5 tons at 100% load
• Bottom fly ashes: 1.2 tons/hour
The challenge
• First major maintenance, July 2011: significant erosion/corrosion
• tube wastage were detected down to 2,0mm
• After the outage decision to upgrade CS water panels with 625
• Revision 2012, WOL ~250m² projected, 9 days inside the boiler
• Existing panels with < 4,0mm tube wall thickness replaced
• ~80m² panels provided with 625 shop overlay Bubbling fluidized bed (BFB)
www.azz.com/wsi-europe 11
Scope of work
• Field overlay above refractory cutline up to elevation 18,5 m
• Replacement of ~80m² prior to weld overlay
• Target area 9,2 m to 18,1 m: ~250m² proj.
• Tie-in work
QA/QC – work conducted in accordance with
• EN 288
• EN-ISO 15614-1
• TUV Merkblatt 1156
Quality/Control
• Thickness on progress
• Thickness
• Chemistry: PMI
• Sealing: copper sulfate
Showcase- MW Power- Vattenfall- Jordbro plant
www.azz.com/wsi-europe 12
Showcase- ENA AB-Enköping-Sweden
Background
•Boiler type: Vibrating grate Burmeister & Wein Energy 80 MW.
•Steam pressure: 101 bar
•Temperature: 540C
•Production: District heating and power
•Fuel: Bio fuels mainly residues from logging, waste from sawmills and
paper mills
•Why Alloy 625 Weld Overlay?
The boiler has been boosted with approximately 10% RT chips since yr 2010.
Because of the lower price of RT-chips compared to other bio fuels, the plant has plans
to change to 100% RT chips. To make sure the tubes in the boiler can cope with the
increased use of RT-chips, improvement of tube metallurgy has to be carried out.
Alloy 625 panel weld overlay in field
2012 July: ~310m²
2013 July: ~250m2
www.azz.com/wsi-europe 13
Field weld overlay
Showcase- ENA AB-Enköping-Sweden
www.azz.com/wsi-europe 14
Protection for superheaters
Welding overlay with alloy 625 for straw and waste wood (temp. limited to 400-540C)
Welding overlay with alloy 310 for recovery boilers
Tig wash process for a smooth surface and to improve ductility. Superheater and or evaporator
bundle made with Unifuse® 360 tubes welded together + manual tie-in
No porosity, no disbonding due to metallurgical bond to base material
www.azz.com/wsi-europe 15
Weld overlay corrosion
At high temperatures, Cr2O3 protective layer
is attacked / volatilized by molten salts, allowing
chlorine to attack (ex. as in T22)
Weld overlay to protect against salt deposit. WOL
Life depends on temperature:
• Corrosion (due to flue gas flow, salt deposits)
• Erosion /corrosion
cross section of a worn 625 overlay waterwall sample
0,5 mm
1,5 mm
Alloy 625
CS tube SEM and EDX on localized corrosion pit on alloy
625 overlay to understand chem. compositions at
different chloride complex phases
30 μm
Severe corroded T22 superheater tube in a
biomass boiler burning hog fuel
www.azz.com/wsi-europe 16
SEM and EDX results
The chemical compositions (wt%) at different phases are:
1: 68% Pb, 11% Mo, 6% Cr, 3% Fe, 3% Ni, 4% S, 3% Cl, and trace elements
2: 63% Pb, 9% S, 6% Cl, 7% Cr, 5% Mo, 2% Fe, 3% Ni, 2% Na, and trace elements
3: 31% Cr, 24% Ni, 2% Fe, 27% Pb, 6% Zn, 5% S, 1% Cl, and trace elements
4: 32% Pb, 14% Cr, 8% Ni, 5% Fe, 10% Mo, 7% Zn, 9% Cl, 5% K, 3% Na, 3% S, and trace elements
5: 52% Pb, 11% K, 13% S, 7% Cl, 6% Mo, 4% Na, 4% Cr, 2% Ni, and trace elements
6: 34% Ni, 23% Cr, 3% Fe, 23% Pb, 7% Zn, 6% Mo, 2% Cl, and trace elements
7: 49% Pb, 12% K, 3% Na, 13% S, 7% Cl, 5% Cr, 6% Mo, 3% Ni, and trace elements
8: 30% Cr, 28% Pb, 13% Ni, 11% Zn, 7% Mo, 6% Cl, 2% K, and trace elements
9: 26% Pb, 22% Ni, 16% Cr, 11% Zn, 7% Cl, 5% Mo, 7% Na, 3% Fe, and trace elements
10: 27% Pb, 19% Cr, 14% Ni, 13% Zn, 9% Mo, 5% Cl, 4% Na, 2% K, and trace elements
11: 54% Ni, 24% Cr, 6% Pb, 5% S, 6% Fe, and trace elements
12: 27% Cr, 19% Ni, 19% Pb, 15% Zn, 9% Mo, 5% Cl, 2% K, 2% Fe, and trace elements
The composition of the deposit and corrosion
products can vary significantly from plant to
plant. In this case, heavy metal corrosion deposits
(Zn and/or Pb) suggest that the corrosion mechanism is
fluxing by molten chloride salts
www.azz.com/wsi-europe 17
• Words from the CUSTOMERS
• "Solid and professional project execution by WSI"
Showcase- MW Power- Vattenfall- Jordbro plant
• Vattenfall
• Euromaint
• ENA Energi
• SYSAV
• Coor Service Management
• E.ON Händelöverket
• Umeå Energi
• Billerud AB
• INEOS A/S
• Fortum Högdalen AB
• Renova
• Boliden Mineral AB
• Halmstad Energi & Miljö
• Södra Cell AB
• Valmet (Metso) Power AB
• Foster Wheeler Oy
• BW Völund
• Andritz
• Rautaruki Steel Oy
WSI referens project Nordic 2004 – up to day
www.azz.com/wsi-europe 18
Future
Inconel 625 limitation:
• Metal temperature
• Erosion/Abrasion properties
WSI has a R&D development program for alternative alloys
Questions!
www.azz.com/wsi-europe 19
THANK YOU!