Suitability of Handheld XRF Analyzer for Recovered Waste Wood and Fly Ash Quality Control
Salvola, Sanni (2015)
2015
Ympäristö- ja energiatekniikan koulutusohjelma
Luonnontieteiden tiedekunta - Faculty of Natural Sciences
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Hyväksymispäivämäärä
2015-02-04
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201501291041
https://urn.fi/URN:NBN:fi:tty-201501291041
Tiivistelmä
Aim of this thesis was to test suitability of handheld x-ray fluorescence (XRF) analyzer for recovered waste wood (RWW) quality control and to find out how it could be utilized in power plant fuel reception. RWW can contain harmful constituents of which especially chlorine and heavy metal content was examined. Findings base on XRF measurements, laboratory analyses, literature, legislation and visits to wood recycling sites and different power plants. XRF device utilized was Niton XL3t GOLDD++.
XRF technology suits best on analyzing homogenous mixtures and flat surfaces. The most feasible method for evaluating the quality of a wood truck was grinding the sample before analysis, providing that sampling is carried out representatively. Sampling plan based on standards EN 14778 and EN 14780. Different wood suppliers and wood fractions were able to be compared together in terms of harmful contents. Painted wood was found out to contain the highest amounts of heavy metals.
In addition to wood, fly ash samples were analyzed successfully with XRF. XRF enabled analyzing elemental composition of fly ash frequently during different fuel mixture trials. It was seen that heavy metals in fly ash come mainly from RWW. Chlorine originated from RWW and drum reject. Fly ash from 2nd and 3rd passes was found out to be cleaner than baghouse filter ash.
Because of deficient calibration and heterogeneous composition, results of wood were not as accurate as the results of fly ash. Heavy elements such as lead were able to be measured pretty accurately, but light elements such as chlorine and sulfur are more challenging for XRF technology. Analysis time of 9 s was seen to be sufficient for detecting the elements present in wood samples (Plastic mode). Accuracy of results increases when analysis time extends. After 90 s the effect of analysis time starts to stabilize.
XRF technology suits best on analyzing homogenous mixtures and flat surfaces. The most feasible method for evaluating the quality of a wood truck was grinding the sample before analysis, providing that sampling is carried out representatively. Sampling plan based on standards EN 14778 and EN 14780. Different wood suppliers and wood fractions were able to be compared together in terms of harmful contents. Painted wood was found out to contain the highest amounts of heavy metals.
In addition to wood, fly ash samples were analyzed successfully with XRF. XRF enabled analyzing elemental composition of fly ash frequently during different fuel mixture trials. It was seen that heavy metals in fly ash come mainly from RWW. Chlorine originated from RWW and drum reject. Fly ash from 2nd and 3rd passes was found out to be cleaner than baghouse filter ash.
Because of deficient calibration and heterogeneous composition, results of wood were not as accurate as the results of fly ash. Heavy elements such as lead were able to be measured pretty accurately, but light elements such as chlorine and sulfur are more challenging for XRF technology. Analysis time of 9 s was seen to be sufficient for detecting the elements present in wood samples (Plastic mode). Accuracy of results increases when analysis time extends. After 90 s the effect of analysis time starts to stabilize.