Haeyang Pak

Characteristics of Pulverized Coal Burner Using a High-Oxygen Partial Pressure

An investigation has been undertaken into the combustion of coal with oxygen. A burner similar to a pulverized coal–air combustion burner modified for combustion with oxygen in a closed system was designed and tested in a bench-scale (145 kW) furnace. Data were obtained after a stable flame was achieved, i.e. stable combustion intensity and combustion products. The fundamental characteristics of the flame were investigated for different stoichiometric ratios (mass of oxygen required per mass of oxygen supplied). The result of stoichiometric combustion shows more than 99.8% burnout, an average CO 2 concentration of 90% and NO x emission lower than 1400ppm in flue gas.

New Mass Spectrometric System for Direct Detection of Intermediate Species in Flames

To obtain energy with high efficiency and reduce the toxic emission during combustion, identification of intermediate chemical species in flames is important for better understanding of reaction mechanisms. We have developed a unique system based on ion attachment mass spectrometry (IAMS) for this purpose. In this system, the chemical species generated in flames under atmospheric pressure are introduced directly through a sampling cone of a newly developed interface into the ionization chamber (2Pa). Then the species are ionized by Li + ion attachment and introduced into a quadrupole mass spectrometer operating at 1 x 10 -3 Pa. Intermediate species in flames have successfully been detected. It should be noted that the production of highly toxic environmental pollutants, such as formaldehyde (HCHO) and acetaldehyde (CH3CHO), were confirmed to be produced during combustion of promising alternative fuels, dimethyl ether (CH3OCH3, DME) and ethanol (CH3CH2OH). Additionally, by moving the burner position for detection of the species at various positions, the

NOx emission and fly ash characteristics from oxygen-blown pulverized coal combustion

Bench scale pulverized coal combustor with oxygen has been designed. Experiment is conducted in a down-fired, cylindrical and vertical furnace. An Indonesian sub-bituminous coal is used for combustion experiment. The heat balance in the furnace is estimated with temperature distributions. High combustion efficiency has been achieved, and it depends on the oxygen ratio and primary and secondary oxygen flow ratio. The NOx concentration is raged from 1650 to 1800 ppm on the complete combustion region, and the conversion ratio of fuel nitrogen to NOx is increased significantly as the oxygen ratio increased. Decreasing of weight fractions of Na, Mg, K and Ca that have lower boiling points in ash is confirmed, since very high temperature flame vaporized these matters.