Ignition modes of pulverized coal clouds

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:549525

Sheng, C ^[1]; Yuan, J; Xu, M; Ma, Y ^[2]

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1. Southeast Univ. (China). Dept. of Power Engineering
2. Huazhong Univ. of Science and Technology (China). National Lab. of Coal Combustion

Experimental investigation on ignition modes of pulverized coal clouds relating to the dust concentration is performed in a drop tube furnace. The clouds are formed by premixing pulverized coal and air with different dust concentrations. Three coal types of widely different rank are used. During the Experiment, a cloud is continuously fed into the furnace. When the cloud flows down, it is heated, ignites, and combusts. A water-cooled probe is applied to sample partially burned solids and gases. Moving the probe along the furnace axis, the solid and gaseous samples at different combustion positions can be collected. The ignition mode of pulverized coal clouds is determined by the following method. The ignition of the clouds is characterized by abrupt increment of CO{sub 2} produced during the combustion. The ignition mode of the cloud is deduced from variation of VM/FC ratio of partially burned solids with the sampling positions. If VM/FC ratio decreases during ignition, the ignition mode of the cloud is homogeneous. Otherwise, if VM/FC ratio keeps constant or increases, it means heterogeneous ignition occurs in the cloud. Sometimes, the variations of consuming degrees of fixed carbon and volatile matter during ignition are used to confirm these judgments. In the experiment, it is found that homogenous ignition occurs if the concentration of pulverized coal is higher. As the concentration decreases, ignition mode transits from homogeneous to heterogeneous. Effects of particle size and oxygen fraction on the transition of ignition modes are also investigated.

• OSTI ID: 549525
• Report Number(s): CONF-960954--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
AEROSOLS
COAL
COMBUSTION KINETICS
CONCENTRATION RATIO
FUEL-AIR RATIO
IGNITION
PARTICLE SIZE
PULVERIZED FUELS
VOLATILE MATTER