The effects of pressure, oxygen partial pressure, and temperature on the formation of N{sub 2}O, NO, and NO{sub 2} from pulverized coal

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Combustion and Flame

DOI:https://doi.org/10.1016/0010-2180(95)00019-3· OSTI ID:116441

Aho, M J; Paakkinen, K M; Pirkonen, P M ^[1]; Kilpinen, P; Hupa, M ^[2]

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1. VTT, Jyvaeskylae (Finland). Energy Research Institute
2. Aabo Akademi Univ., Turku (Finland). Dept. of Chemical Engineering

The main features of a new, pressurized, entrained-flow reactor are described and results presented of experiments investigating the formation of nitrogen oxides from pulverized Polish coal, burned in the reactor at temperatures (T) 800--1,300 C, pressures (p) 1--20, bar and oxygen partial pressures (pO{sub 2}) 0.05--2.4 bar. The experimental results are compared with the results of detailed gas-phase kinetic calculations at 850 C, where HCN was used as the source of coal-nitrogen, and H{sub 2}, H{sub 2}O, CO and C{sub 2}H{sub 4} were used to describe the gaseous products of pyrolysis and char combustion. NO formation decreased sharply with pressure and increased with pO{sub 2} and T. Total pressure and pO{sub 2} did not affect N{sub 2}O formation in the pO{sub 2} range 0.15--0.6 bar. At higher pO{sub 2} the conversion of fuel-N to N{sub 2}O decreased with both total pressure and pO{sub 2}. An increase in T strongly reduce N{sub 2}O formation, independently of pressure and pO{sub 2}. No N{sub 2}O was found at or above 950 C. NO{sub 2} was formed in sufficient concentrations to find a regression model at high partial pressures (>0.5 bar) of oxygen. Like N{sub 2}O formation, the yield of NO{sub 2} decreased with T. But like NO, and in contrast to N{sub 2}O, the formation of NO{sub 2} increased with pO{sub 2}. NO was the only nitrogen oxide produced above 1,000 C at 4--16 bar. Concentrations of NO, NO{sub 2} and N{sub 2}O obtained in kinetic computations showed similar trends to the measured values. Calculations also showed the concentration of O, OH and H radicals to decrease with pressure and also that HO{sub 2} becomes the dominating radical at high pressures.

• OSTI ID: 116441
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 3 Vol. 102; ISSN 0010-2180; ISSN CBFMAO
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
CHEMICAL REACTION YIELD
COAL
COMBUSTION KINETICS
FUEL-AIR RATIO
KINETIC EQUATIONS
NITRIC OXIDE
NITROGEN DIOXIDE
NITROUS OXIDE
PRESSURE DEPENDENCE
PULVERIZED FUELS
REACTION INTERMEDIATES
TEMPERATURE DEPENDENCE