Case study of solid biofuels online quality measurement using novel x-ray technology

摘要

In bioenergy production, the solid fuel quality and especially moisture content and share of foreign matter are the key parameters. The water content of the fuel is a parameter used in controlling combustion process. It is also essential for verifying energy content of the fuel delivered to the power plant, which is base for fuel pricing. Moisture content of biofuels varies a lot and they often contains foreign matter such as stones, sand, soil and metals which lowers energy content, decreases plants efficiency and increases the operation and maintenance costs. Current fuel quality control practice bases mainly on manual sampling method where typically, one sample of each truckload is taken and composite samples are analysed in laboratory. Normally only moisture content is analysed in regular basis. This method is unreliable in and requires a lot of manual work. New online biofuel quality measurement system, Inray Fuel, has been recently developed that has several benefits compared to the current practice. System was installed to UPM- Kymmene Oyj’s Kaipola biopower plant (117 MWth) in Finland in November 2013. The target was to demonstrate Inray Fuel online X-ray scanner in relevant environment with challenging solid biofuels in moisture and foreign matter measurement. Measurement location was at the fuel receiving in a belt conveyor after biomass crusher. UPM-Kymmene Oyj organised an intensive test period 10~(th) to 13~(th) of March 2014 where online measurement was compared to current sampling based practise. Tested fuels were forest residues, stem wood chips, whole tree chips and crushed stumps. Totally 45 truckload’s fuel quality was determined. Results shows that current practise is inaccurate because of high moisture content variations within a truckload, which makes reliable sampling challenging. Inray Fuel system was found to be more accurate than current methods because of online measurement eliminates moisture variations, enables foreign matter analysis and more accurate energy content analysis.