Oxy-fuel combustion kinetics and morphology of coal chars obtained in N2 and CO2 atmospheres in an entrained flow reactor

M.V. Gil, J. Riaza, L. Álvarez, C. Pevida, J.J. Pis and F. Rubiera

Applied Energy, 2012, vol. 91, issue 1, 67-74

Abstract: The thermal reactivity and kinetics of four coal chars (HVN, UM, SAB and BA) in an oxy-fuel combustion atmosphere (30%O2–70%CO2) were studied using a thermobalance. The coal chars were obtained by devolatilization in an entrained flow reactor (EFR) at 1000°C for 2.5s under 100% N2 and CO2 atmospheres. The reactivity tests were carried out by isothermal thermogravimetric analysis at different temperatures in a kinetically controlled regime. Three nth-order representative gas–solid models – the volumetric model (VM), the grain model (GM) and the random pore model (RPM) – were employed in order to describe the reactive behaviour of the chars during oxy-fuel combustion. From these models, the kinetic parameters were determined. The RPM model was found to be the best for describing the reactivity of the HVN, UM and BA chars, while VM was the model that best described the reactivity of the SAB char. The reactivities of the chars obtained in N2 and CO2 in an oxy-fuel combustion atmosphere with 30% of oxygen were compared using the kinetic parameters, but no differences were observed between the two devolatilization atmospheres. The apparent volatile yield after the coal devolatilization under CO2 in the EFR was greater than under N2 for all the coals studied. According to the scanning electron microscopy (SEM) images of the chars, those obtained in the CO2 atmosphere experienced a greater degree of swelling, some particles showing partially reacted surfaces indicative of reaction between the char and CO2.

Keywords: Coal; Char; Isothermal TG; Oxy-fuel combustion; Kinetics models; Entrained flow reactor (search for similar items in EconPapers)
Date: 2012
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (21)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0306261911005885
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:91:y:2012:i:1:p:67-74

Ordering information: This journal article can be ordered from
http://www.elsevier.com/wps/find/journaldescription.cws_home/405891/bibliographic
http://www.elsevier. ... 405891/bibliographic

DOI: 10.1016/j.apenergy.2011.09.017

Access Statistics for this article

Applied Energy is currently edited by J. Yan

More articles in Applied Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().