Thermal degradation of driftwood: Determination of the concentration of sodium, calcium, magnesium, chlorine and sulfur containing compounds

Published Date 

Waste Management

February 2017, Vol.60:151–157, doi:10.1016/j.wasman.2016.08.035

Special Thematic Issue: Urban Mining and Circular Economy

Author 

• P. Bartocci ^,
• M. Barbanera
• M. D’Amico
• P. Laranci
• G. Cavalaglio
• M. Gelosia
• D. Ingles
• G. Bidini
• C. Buratti
• F. Cotana
• F. Fantozzi

• Department of Engineering, University of Perugia, Via G. Duranti, 06125 Perugia, Italy

Received 4 May 2016. Revised 4 August 2016. Accepted 29 August 2016. Available online 2 September 2016. 

Highlights

• •
  Gasification releases about 45%w alkaline earth metals in driftwood.
• •
  Combustion releases about 55%w alkaline earth metals in driftwood.
• •
  Gasification and combustion release respectively 65% and 80% of alkali metals.
• •
  Pyrolysis at 600 °C has a low release of chlorine, calcium and magnesium.

Abstract

The annual production of driftwood in Italy has been estimated to be more than 60,000 tonnes. This wood can be used as an energy source. Particular attention should be paid to its content of alkali and alkaline earth metals, sulfur and chlorine. Few works are available in the literature on this topic. For this reason, the authors propose experimental tests of combustion, gasification and pyrolysis, to evaluate the fate of alkali and alkaline earth metals, sulfur and chlorine in the solid residues and compare the three thermal degradation technologies. The results show a release of alkaline earth metals of about 45% of the initial quantity for gasification and a release of 55% of the initial quantity for combustion (while pyrolysis at 600 °C has a very low release). The release of sodium is about 65% for gasification and 80% for combustion. It can be seen that the release of sodium is higher than that of alkaline earth metals; this is due to the divalency of the last ones. Dealing with the release of major elements (chlorine, sulfur and AAEMs) the tests have shown that pyrolysis process is a low emitting technology.

Keywords

Driftwood

Pyrolysis

Gasification

Combustion

Alkali metals

Chlorine

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Nomenclature

α

release ratio [–]

m

content of alkali metals and alkaline earth metals [%w]

CHP

Combined Heat and Power [–]

HHV

Higher Heating Value [MJ/kg]

ICP

Inductively Coupled Plasma [–]

OES

Optical Emission Spectrometry [–]

AAEM

Alkali and Alkaline Earth Metals [–]

Subscript

rm

raw material [–]

td

thermally degraded sample [–]

 Table 1

Table 1.

 Table 2

Table 2.

 Table 3

Table 3.

Fig. 1.

Fig. 2.

 Table 4

Table 4.

 Table 5

Table 5.

Fig. 3.

 Table 6

Table 6.

Fig. 4.

• ⁎ 
  Corresponding author.

© 2016 Elsevier Ltd. All rights reserved.

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