• Hämäläinen, Jouni
• Suomalainen, Anne
• Mäkipää, Markku
• Orjala, Markku
• Vainikka, Pasi
• Kärki, Janne

Abstract

Utilisation of solid biofuels and wastes sets new demands for fuelhandling and feeding systems, as well as for boiler design and combustiontechnologies. Especially ash quality of wood fuels differs remarkablychemically from ashes of peat or coals and other fossil fuels. The alkalinemetals, which are usually responsible for fouling of heat transfer surfaces,are abundant in wood and will be released during combustion easily in gasphase. The combustion and co-firing properties of fuels have been studied bothin VTT's test facilities and in industrial-scale power plant boilers. Theformation of alkaline and chlorine compounds and their effect on boilerfouling and corrosion have been monitored by cooled temperature controlleddeposit and material probes. The experimental studies clearly showed that ifsulphur existed in combustion environment, chlorine was released as HCl anddid not drift into deposits. Fouling of the boiler effects on several factorsat the plant. These factors, e.g. the increment of operating and maintenancecosts caused by fouling of the boiler, can increase the energy productioncosts significantly. In addition to increased need for soot blowing andcleaning, as well as the possible renovation need of the super heaters, theefficiency of the boiler decreases as thermally insulating ash deposits on theheat transfer surfaces of the boiler. By the side of these factors costs arecaused by more often replaced bed material, the increased need for powerconsumption of the plants, and storage costs of wood fuels

Topics

• surface
• compound
• corrosion
• combustion
• wood