Investigation on Ash Slagging Characteristics During Combustion of Biomass Pellets and Effect of Additives

This study reports a systematic investigation into ash slagging behavior during combustion of barley straw and barley husk pellets with or without additives in a residential pellet burner. The slagging tendencies of the pellets were evaluated based on the amount, chemistry, mineralogy, and morphology of inlet ash formed as slag and sintering degrees of residual ash. The barley straw and husk pellets showed high slagging tendencies with 39 and 54 wt % ingoing ash formed as slag. Analyses using X-ray fluorescence and scanning electron microcopy combined with energy-dispersive X-ray spectroscopy revealed high concentrations of K, Si, and Ca but a minor amount of P in barley straw slag. The slag mainly contained melted potassium silicates directly observed by X-ray diffraction. For the barley husk, high ash slagging tendency was observed and mainly attributed to the formation and melting of potassium phosphates, potassium silicates, and complex mixtures of the two mineral phases. Addition of marble sludge completely eliminated ash slagging during combustion of barley straw and husk pellets because it led to the formation of high temperature melting calcium potassium phosphates, calcium rich potassium silicates, and oxides. Addition of calcium lignosulfonate showed a less pronounced ability to mitigate ash slagging issues during pellet combustion, although it promoted the formation of calcium-rich silicates and phosphates (both with high-melting points) in barley straw and husk ash, respectively. This process was accompanied by considerable reduction in the amount and sintering degree of the formed barley straw and husk slag

Norwegian households' perception of wood pellet stove compared to air-to-air heat pump and electric heating

In 2003, the high dependency on electric heating combined with the high electricity price prompted a significant number of Norwegian households to consider alternative heating systems. The government introduced economic support for wood pellet heating and heat pumps. In contrast to the fast growing heat pump market, this financial support has not resulted in a widespread adoption of wood pellet heating. This paper studies factors that influence the choice of heating system based on Norwegian households' perceptions. Electric heating, heat pump and wood pellet heating were compared, with a special focus on wood pellet heating. This study was conducted as a questionnaire survey on two independent samples. The first sample consisted of 188 randomly chosen Norwegian households, mainly using electric heating; the second sample consisted of 461 households using wood pellet heating. Our results show that socio-demographic factors, communication among households, the perceived importance of heating system attributes, and the applied decision strategy all influence the Norwegian homeowners. The significance of these factors differs between the two samples and the preferred type of anticipated future heating system. Strategies for possible interventions and policy initiatives are discussed.Norwegian perception Heating choices Multinomial logistic regression (MLR)