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Biomass Conversion and Biorefinery

, Volume 9, Issue 1, pp 71–82 | Cite as

Influence of wood chip quality on emission behaviour in small-scale wood chip boilers

  • Claudia Schön
  • Daniel Kuptz
  • Robert Mack
  • Volker Zelinski
  • Achim Loewen
  • Hans HartmannEmail author
Original Article

Abstract

The introduction of wood chips into the market for small-scale heating appliances of below 100 kW has become more challenging due to stricter regulations on emission levels for carbon monoxide and particle emission, e.g. in Germany. Therefore, it is important to identify high wood chip qualities that are suitable for failure-free and low-emission combustion. In this investigation, several wood chip assortments produced from stem wood and forest residues were analysed and combusted in up to two different wood chip boilers with a nominal heat capacity of 50 and 99 kW at full load. Some combustion tests were performed at part load (i.e. 30% heat output). Throughout experiments, the emission behaviour was measured (CO, NOX and total particulate matter (TPM)). In total, seven different wood chip assortments were tested in the large boiler, whereas ten wood chip assortments were combusted in the smaller furnace. Wood chips from stem wood are characterized by lower ash contents (0.27–1.05 w%, d.b.), lower nitrogen contents (0.04–0.14 w%, d.b.) and lower aerosol forming elements (379–1075 mg/kg, d.b.) compared to forest residues (A = 0.58–2.05 w%¸ N = 0.13–0.32 w%, aerosols = 728–2199 mg/kg, d.b.). Combustion of stem wood caused lower emissions compared to forest residues at full-load operation. Overall, part-load operation caused higher CO and particle emissions. In addition, increases of fine woody particles lead to increases in CO emissions. The influence of moisture content was more pronounced especially for CO emissions.

Keywords

Wood chip quality Fines Moisture content Emission behaviour Combustion tests 

Abbreviations

A

Ash content

a.r.

As received

BD

Bulk density

CO

Carbon monoxide

d.b.

Dry basis

DIN

Deutsches Institut für Normung (German Institute for Standardization)

EN

European standard

FTIR

Fourier transform infrared spectroscopy

MC

Moisture content

NOX

Nitrogen oxides

PM1

Particles ≤1 μm

Q

Net calorific value

STP

Standard temperature and pressure

TPM

Total particulate matter

VDI

Verein Deutscher Ingenieure (The Association of German Engineers)

WC

Wood chips

Notes

Acknowledgments

This research was funded by Federal Ministry of Agriculture by decision of the German Bundestag with the Fachagentur Nachwachsende Rohstoffe e. V. (FNR) as project executing organization within the projects OptiChip and HackZert. We thank our colleagues Elisabeth Rist, Albert Maierhofer, Benedikt Haas, Stephan Winter and Anja Rocktäschel for their support during these studies.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  • Claudia Schön
    • 1
  • Daniel Kuptz
    • 1
  • Robert Mack
    • 1
  • Volker Zelinski
    • 2
  • Achim Loewen
    • 2
  • Hans Hartmann
    • 1
    Email author
  1. 1.Department of Solid BiofuelsTechnology and Support Centre in the Centre of Excellence for Renewable Resources (TFZ)StraubingGermany
  2. 2.University of Applied Science and ArtGöttingenGermany

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