Elohopean ja muiden hivenaineiden höyrystyminen pyrolysoitaessa hiiltä ja jätepolttoaineita leijupetireaktorissa
Notice bibliographique
Résumé
The objective of this thesis was to investigate the release of mercury and other trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Tl, V, Zn, Ti and Se) from coal and waste derived fuels during pyrolysis in a bubbling fluidised bed reactor. The release of mercury was of particular interest, as it is the most volatile, difficult to control and causes greatest public health concern of all trace elements. In addition to this, mercury exists in flue gas in three forms: gaseous elemental mercury, gaseous oxidised mercury and particulate bound mercury. It is imperative to know the speciation of mercury in order to address questions concerning mercury emission control, toxicity, mobility, bioaccumulation, and atmospheric fate and transport because each form has different physical, chemical and biological properties. In the theoretical part of this thesis, the sources, health effects, legislation and behaviour of trace elements during thermal processes are introduced, with special focus on mercury. Measurement of trace elements in and their removal from flue gas are also discussed. The focus of the reviewed literature was placed on the most recent studies conducted. In the experimental part of this thesis, the release of mercury and other trace elements from coal, sewage sludge and automotive shredder residue during pyrolysis in a fluidised bed reactor was examined. Mercury emissions were measured by a manual, wet sampling method, Ontario Hydro Method, which has an ASTM standard. Other trace elements were sampled by directing the flue gas flow through a scrubber tank containing of 15 litres of HNO3/H2O2 liquid, of which samples were taken during the test. The compositions of bed sand, fuel and char were also analysed. FTIR gas analyser was used to measure concentrations of about 20 gaseous species in the flue gas. The release of trace elements and the speciation of mercury were evaluated based on the results of these measurements and analyses. According to previous studies, mercury is completely volatilised during combustion and gasification processes and almost completely vaporised during pyrolysis in temperatures below 600 °C. Other trace elements can be released in gaseous form, enriched in fine particles or stay in the bottom ash depending of the characteristics and of the mode of occurrence of the particular trace element. During the experiments, it was noticed that all of the mercury was vaporised from each of the fuels used already at below 320 °C. The behaviour of other trace elements was dependent of the fuel as both vaporisation and enrichment in the char was detected.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,003 | 0,003 |
| Méta-épidémiologie (sens large) | 0,002 | 0,001 |
| Bibliométrie | 0,007 | 0,004 |
| Études des sciences et des technologies | 0,001 | 0,001 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,004 | 0,002 |
| Intégrité de la recherche | 0,002 | 0,002 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,010 | 0,036 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; les deux têtes enseignantes s’accordent sur ce qui est montré ici.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».