Partitioning of sodium, chlorine and sulfur during coal and char combustion in a fluid bed

Conference · Thu Dec 31 04:00:00 EST 1998

OSTI ID:349073

Bhattacharya, S P; He, Y ^[1]

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1. Cooperative Research Centre for New Technologies for Power Generation from Low-Rank Coal, Mulgrave, Victoria (Australia)

Advanced power generation technologies (IGCC, Advanced PFBC) using high moisture low-rank coals require gasification of coal followed by combustion of char in a fluid bed. A study was undertaken to investigate the bed behaviour of char during combustion in a fluid bed. Three high moisture Australian low-rank coals, which are currently used in Victorian power stations, were chosen for this study. These were air dried, ground and sieved to 1--4 mm size. Char was prepared from these coals by devolatilising in a 76-mm diameter spouted bed at 700 C in presence of nitrogen. Char samples were combusted in the same spouted bed under hydrodynamic conditions similar to that in an atmospheric circulating fluid bed at temperatures of 800 C and 900 C. The three coal samples were also combusted under similar conditions to compare with the combustion behaviour of the char. No significant agglomeration problems were observed during combustion of these coals for periods of up to four hours. For one char, the bed defluidized 70 minutes after combustion at 900 C, while the two remaining chars didn`t present any significant agglomeration during the test period of four hours. Ultimate and inorganic analyses were carried out for the coal and char samples before the tests. The bed materials and cyclone ash after each combustion test were analyzed for inorganics and phases using chemical analysis, XRD and DTA techniques. A significant separation of the sodium and chlorine in coal was observed during pyrolysis of the coal to char. During combustion of char, most of the sodium (in char) was captured in the bed materials. This information was used to explain the bed behaviour observed during char combustion. This paper discusses the results and suggest strategies for mitigation of defluidization, that are currently under trial.

• OSTI ID: 349073
• Report Number(s): CONF-980985--; ISBN 1-890977-15-2
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
20 FOSSIL-FUELED POWER PLANTS
BROWN COAL
CHARS
CHLORINE
COAL GASIFICATION
COMBINED-CYCLE POWER PLANTS
DISTRIBUTION
FLUIDIZATION
FLUIDIZED-BED COMBUSTION
SODIUM
SULFUR