DIOXIN EMISSIONS FROM SMALL-SCALE COMBUSTION OF BIO-

0,46

MB

FUEL AND HOUSEHOLD WASTE

62

stron

3485

ID

Umeå universitet

2005

rok

TABLE OF CONTENTS

1 INTRODUCTION..1

2 BACKGROUND..2

2.1 Dioxin nomenclature, structures and environmental relevance.2

2.2 Formation of dioxins3

2.2.1 Temperature.5

2.2.2 Oxygen. ..5

2.2.3 Particles (soot and fly ash) ..6

2.2.4 Catalysts and inhibitors .6

2.2.5 How does the chlorine content affect dioxin formation? ..7

2.2.5 Profiles8

2.3 Waste management ..8

2.3.1 Waste characterizations..10

2.4 Waste combustion ..12

2.5 Dioxins in waste..12

2.6 Biofuel..12

2.6.1 Reed canary-grass .13

2.6.2 Environmental problems associated with biofuels.14

2.7 Combustion principles .15

2.8 Backyard burning15

3 EXPERIMENTAL ..16

3.1 General outline of trials..16

3.2 Materials.17

3.2.1 Waste fuels .17

3.2.2 Biofuels 17

3.2.3 Combustion equipments ..18

3.3 Methods19

3.3.1 Sorting analysis19

3.3.2 Logging equipment.19

3.3.3 Sampling flue-gas20

3.3.4 Analysis21

4 RESULTS AND DISCUSSION23

4.1 Sorting analysis of source-sorted waste (Papers I and II).23

4.1.1 Chlorine and PCDD/F in waste fractions and fuel23

4.1.2 Flow of dioxins, Recycle or incinerate – contaminated waste? ..28

4.2 Co-combustion of biofuel and RDF (Papers I and II)..28

4.3 Combustion of pellets and fire-wood in residential stoves and boilers (Paper III) ..29

4.4 Backyard burning (Paper IV) ..30

4.5 Contents of fuels and their significance for combustion emissions (Papers I-IV) .32

4.5.1 The significance of chlorine contents for dioxin emissions32

4.5.2 Information provided from homologue profiles ..37

5 CONCLUSIONS AND SUGGESTIONS FOR FUTURE WORK.40

6 ACKNOWLEDGEMENTS42

7 REFERENCES..43