Abstract
Biomass burning for production of electricity and heat
has been increasing due to legislation in Europe. Growing
awareness of environmental problems has led to strict
restrictions on greenhouse emissions in the energy
sector, and increased demand for higher use of renewable
energy sources and carbonneutral fuels, such as biomass.
There are over 1000 biomass boilers in Europe, and the
number is increasing. These plants often face serious
problems due to high temperature corrosion. Fouling and
corrosion in biomass boilers can lead to tube failure and
leakage. In addition, demand for higher efficiency of
electricity and heat generation requires an increase in
steam temperatures, which raises the material
temperatures of boiler tubes and may result in more
severe corrosion problems. To overcome corrosion damages
to boilers, commonly used low-alloyed steels are being
replaced by higher-alloy tube materials. However, the
high price and sometimes difficult machinability of these
materials hinders their adoption. Thermal spray coatings
can offer an attractive solution for corrosion protection
of boiler tubing.
The objective of this work was to determine the corrosion
resistance of thermal spray coatings in biomass
combustion conditions. The overall research aim wasto
enhance the lifetime of the heat exchanger surfaces of
biomass power plant boilers. The research focused mainly
on improving the high temperature corrosion resistance of
thermal sprayed HVOF (high velocity oxy-fuel) coatings by
optimizing their structure and verification of corrosion
performance in biomass boiler conditions. Focus was also
placed on determining the corrosion mechanisms of nickel-
and iron-based coatings. The corrosion performance of the
selected coatings was validated in both laboratory
conditions and real biomass boiler conditions. According
to this research, the tested HVOF sprayed nickel- and
iron-based coatings can offer protection for low-alloy
substrates in biomass boiler conditions. The results of
the present study will help optimize the coating process
for high temperature corrosion applications, and in
adopting the use of thermal spray coatings for protection
of the heat exchanger surfaces of biomass boilers.
| Original language | English |
|---|---|
| Qualification | Doctor Degree |
| Awarding Institution |
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| Supervisors/Advisors |
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| Award date | 23 Jan 2015 |
| Place of Publication | Espoo |
| Publisher | |
| Print ISBNs | 978-951-38-8206-8 |
| Electronic ISBNs | 978-951-38-8207-5 |
| Publication status | Published - 2015 |
| MoE publication type | G4 Doctoral dissertation (monograph) |
Keywords
- thermal spray
- coating
- process optimization
- high temperature corrosion
- biomass burning
- corrosion protection