Drying and devolatilization of large coal particles under combustion conditions

Wildegger-Gaissmaier, A. E.; Agarwal, Pradeep K.

doi:10.1016/0016-2361(90)90256-p

Cited by 27 publications

(10 citation statements)

References 22 publications

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“…those by Dincer and Dost (1995a) (1993) and Yang and Wang (1990). The kinetics of coal devolatilization, devolatilization rates, experimental factors affecting coal devolatilization, the effect of pressure on devolatilization and the devolatilization and combustion characteristics of coal particles have also been investigated by Niksa and Lau (1993), Jia et al (1993), Lee (1990, Wildegger-Gaissmaier andAgarwal(1990) and Saxena (1990). However, the number of articles on heat transfer coefficients in fluidized bed applications is low (see for example George, 1993;Tsukada and Horio, 1992).…”

Section: Introductionmentioning

confidence: 94%

A method of determining thermal parameters of granular coal particles during devolatilization

Dinçer

Dost

1996

Int. J. Energy Res.

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SUMMARYFluidized bed combustion offers great potential for the utilization of high-sulphur coal and low-grade coal in an environmentally acceptable manner. Utilization of fluidized bed technology, especially for the combustion of low quality lignites, enables pollutant emission control as well as efficient combustion. The most important stage during the combustion of coal particles is devolatilization, in which various factors such as heat transfer from the surroundings to the particle surface, heat conduction within the particle, the chemicals involved, the kinetics and the transport of volatile compounds within the particle play significant roles. The heat transfer coefficient, thermal diffusivity, thermal conductivity, heating coefficient and lag factor are the most significant thermal parameters in this process. In this study, a 1-D transient heat transfer analysis is carried out for a granular coal particle during devolatilization in a fluidized bed. The particle is idealized as a spherical solid body. Models are developed to determine the thermal parameters of such particles, and are verified using experimental centre temperatures of a 10mm granular coal particle subjected to devolatilization at a medium temperature of 960K. The data are taken from the literature. The results show that the thermal parameters determined here are in good agreement with experimental findings.

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Section: Introductionmentioning

confidence: 94%

A method of determining thermal parameters of granular coal particles during devolatilization

Dinçer

Dost

1996

Int. J. Energy Res.

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“…Some earlier work concentrated mainly on the analysis of theoretical and experimental heat transfer in the coal particles subjected to the fluidized bed combustion and devolatilization (Agarwal, 1991;Wildegger-Gaissmaier & Agarwal, 1990;Agarwal & la Nauze, 1989;Agroskin, 1957). In this study, an analytical technique is used to analyze transient heat transfer for estimating the dimensionless center temperature distributions during heating of the spherically shaped Modeling Consider that a brick particle is placed in a fluidized bed combustor and is exposed to heating by the airstream.…”

mentioning

confidence: 99%

Transient Heat Transfer During Heating of Spherical Particles in a Fluidized Bed

Dinçer

1997

Energy Sources

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This article presents an analytical model for analyzing transient heal transfer between a brick particle and air flow during heating in a fluidized bed combustor. Both experimental and fheoretical studies were carried out. The experimental inuestigation provided the temperature distributions at the centers of the spherical particles during heating. These data were presented in the dimensionless form and were compared with the results of the present analytical model. The modeling includes two heat transfer coefficienl cases. In the first case, heat transfer coefficient is the only conuection heat transfer coefficient, and in the second case, it is the sum of the conuection and radiation heat transfer coefficients. In the comparison between erperimental data and theoretical results, better agreement was found for the second case. The present results indicate that the radiation heat transfer coefficient has a signijicant effect on transient heat transfer from the single object and should be taken into consideration.

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“…Το θεωρητικό πρότυπο σχεδιασµού ακολουθεί την προσέγγιση της παράλληλης διεξαγωγής των δράσεων ξήρανσης, πυρόλυσης (αποπτητικοποίησης) και αεριοποίησης σε µη-ισοθερµοκρασιακό αντιδραστήρα εµβολικής ροής [158]. του γαιάνθρακα, που αφορά κυρίως στα ελαφρά πτητικά συστατικά του [143].…”

Section: γενικάunclassified

“…Υπάρχουν πειραµατικές ενδείξεις (Johnson,[73],p.162) ότι η παράµετρος αυτή δεν επηρεάζει ουσιαστικά το ρυθµό της αεριοποίησης LRGS. Αντίθετα, φαίνεται να επηρεάζει σηµαντικά το ρυθµό της αποπτητικοποίησης σύµφωνα µε ερευνητική εργασία των Wildegger-Gaismaier and Agarwal [143]. Το θεωρητικό πρότυπο αποπτητικοποίησης που χρησιµοποιείται στην παρούσα εργασία επιβεβαιώθηκε πειραµατικά από τον Merrick µε χρήση σχετικά µεγάλων σωµατiδίων γαιάνθρακα (-3mm) [177] ( ) (…”

Section: επίλυση και αποτελέσµαταunclassified

“…δεδοµένα του χρόνου παραµονής (Πίνακας 31) είναι εξαπλωµένα σε ένα ευρύ διάστηµα χρόνου που απλώνεται από τιµές της τάξης των 6-8 min έως και τιµές που ξεπερνούν τα 100 min. Όπως προβλέπουν οι µελέτες κινητικών ξήρανσης[142], µικροί χρόνοι ξήρανσης (δηλ., χρόνοι των 7-15 min που συγκρίνονται µε κάποια t (ή τ) του Πίνακα 31) µπορούν να θεωρηθούν επαρκείς για τη ξήρανση τροφοδοσιών κονιοποιηµένου λιγνίτη, ενώ τιµές της τάξης του t ≈ 60min ή και υψηλότερες θα µπορούσαν να απαιτούνται για την ξήρανση και πυρόλυση αδροµερών σωµατιδίων λιγνίτη[142,143].Αναφορικά µε το παρακράτηµα των στερεών, ιδιαίτερο ενδιαφέρον παρουσιάζει η εστίαση στη δοκιµή 10 του Πίνακα 31 και ιδιαίτερα στο συντελεστή πλήρωσης του…”

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Αλλοθερμική Αεριοποίηση Στερεών Καυσίμων

Χατζηλυμπέρης¹,

Hatzilyberis²

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Drying and devolatilization of large coal particles under combustion conditions

Cited by 27 publications

References 22 publications

A method of determining thermal parameters of granular coal particles during devolatilization

A method of determining thermal parameters of granular coal particles during devolatilization

Transient Heat Transfer During Heating of Spherical Particles in a Fluidized Bed

Αλλοθερμική Αεριοποίηση Στερεών Καυσίμων

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