• Hämäläinen, Jouni
• Järvinen, Timo
• Orjala, Markku
• Vainikka, Pasi
• Kärki, Janne

Abstract

There is a growing interest in utilising renewable fuels in multifuel applications. Main reasons for this are environmental; reduction of CO₂ emissions as well as NO_x and SO₂ emissions. The cofiring, defined assimultaneous combustion of different fuels in the same boiler, thereforeprovides an alternative to achieve lower emission in energy and powerproduction. However, the utilisation of solid biofuels and wastes sets newdemands for process control and boiler design, as well as for combustiontechnologies, fuel blend control and fuel handling systems. The ash behaviourin combustion of biomass-based fuel affects highly on it's combustioncharacteristics compared to peat and coal. Combustion and cofiring propertiesof fuels have been studied both in pilot scale testing at VTT and inindustrial-scale power plant boilers. The formation of alkaline and chlorinecompounds in biomass combustion and their effect on boiler fouling andcorrosion have been monitored by temperature controlled deposit formation andmaterial monitoring probes. Deposit formation monitoring at full-scale boilersprovides unique information on the rate of deposit formation, the effect ofsoot blowing and consequent changes in heat transfer. Additionally, the datafrom deposit formation monitoring has been shown to correlate with boilerperformance, which gives basis for studying the interrelation of: fuel blendcharacteristics - deposit formation - boiler performance. By the aid of theaforementioned means, optimum share of biomass fuel in different fuel blendscan be defined.

Topics

• impedance spectroscopy
• combustion