The release of nitrogen in the combustion and pyrolysis of coals and macerals

Conference · Sat Dec 31 04:00:00 EST 1994

OSTI ID:254785

Hindmarsh, C J; Varey, J E; Thomas, K M ^[1]

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1. Univ. of Newcastle, Newcastle upon Tyne (United Kingdom)

The release of nitrogen oxides is controlled to an extent by the combustion conditions but there are also variations due to coal properties. In low NO{sub x} burners and fluidized bed combustion, fuel nitrogen is the major contributor to NO{sub x} formation. Therefore an understanding of the nitrogen in coal and its release during combustion is an important consideration. Coals are a complex heterogeneous material with a cross-linked macromolecular structure. This gives rise to problems when characterising the coal for combustion purposes. This structural heterogeneity can be described at a variety of levels. At the macroscopic level coals may have a banded structure. At the microscopic level the structure may be described as microscopic components, macerals or associations of macerals which are termed microlithotypes. Macerals can be separated and have distinct physical and chemical properties, for example, volatile matter, nitrogen content, reactivity etc. When considering coal the heterogeneity must be considered since the small particles used in pulverised fuel (pf) combustion, depending on the coal, may be regarded as pure macerals or associations of macerals. When considering the nitrogen in coal at the molecular level the nitrogen functionality must be considered. The nitrogen may be described as pyrrolic, pyridinic or quaternary nitrogen. The objective of this paper was to study the release of coal nitrogen as NO{sub x} during temperature programmed combustion of coals and macerals, with the emphasis being on the identification of reactive intermediate species and a comparison of the differences between macerals.

• OSTI ID: 254785
• Report Number(s): CONF-940813--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
COAL
COMBUSTION
DEVOLATILIZATION
IGNITION
MACERALS
NITROGEN OXIDES
PYROLYSIS
REACTION INTERMEDIATES
TEMPERATURE DEPENDENCE
VOLATILE MATTER