The importance of two sources of NO formation, nitrogen in combustion air
and nitrogen in the fuel, during black liquor combustion was studied using a laminar
entrained flow reactor. Pyrolysis and combustion experiments were conducted in
nitrogen atmosphere and in a mixture of argon and helium in the composition 99%
argon, 1% helium. The experiments were performed at three different temperatures:
700, 900, and 1100��C and at two residence times: 0.6 and 1.6 seconds. The results
indicated that there was NO formation from the combustion air which was found to be
prompt NO. There was NO formation from combustion air at all temperatures, and it
decreased as temperature increased. Depending on conditions, prompt NO formation
accounted for 6-80% of the total NO formation.
NO reduction experiments were conducted to investigate the effect of molten
sodium carbonate on NO reduction. The experiments were performed at two different
temperatures, 800��C which is lower than the melting point of sodium carbonate and
900��C which is higher than the melting point of sodium carbonate. The rate constant
for NO reduction was calculated and was found to agree well with that obtained in a
previous study. The effect of the molten sodium carbonate on NO reduction was found to be negligible during black liquor pyrolysis. The rate in absence of any reducing gas
components could explain NO reduction during black liquor combustion only to a
limited extent.
Models for nitrogen evolution during pyrolysis and combustion were developed
by using data from previous studies. A model for nitrogen release during pyrolysis was
developed as a function of residence time and temperature. Nitrogen release during
pyrolysis was also found to be directly proportional to carbon release and the rate of
nitrogen evolution with respect to the rate of carbon evolution decreased as
temperature increased. / Graduation date: 1997
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/34401 |
| Date | 21 February 1997 |
| Creators | Rompho, Nopadol |
| Contributors | Iisa, Kristiina |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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