The ignition characteristics and combustion processes of coal gangue under different hot coflow conditions in O₂/CO₂ atmosphere: in pellet form

ABSTRACT

The ignition characteristics and combustion processes of coal gangue pellets in O₂/CO₂ atmosphere were studied in a drop tube furnace with oxygen concentration range from 21% to 100%, the experimental gas flow temperature was set to 923, 1023, and 1123 K, and the flow rate was considered to be 5 L/min, 10 L/min, 20 L/min. High-performance camera which can film video at the speed of 60 frames per second was used to seize the ignition phenomena and volatile combustion process. The transformation of ignition mechanism between heterogeneous and homogeneous was found at 21% and 100% oxygen concentrations when the temperature was 923 K at a flow rate of 10 L/min, while the turning point changed to 30% and no more than 30% when the temperature was 1023 and 1123 K, respectively. Both the ignition delay and internal ignition temperature decreased with increasing temperature and oxygen concentration. The volatile combustion burnout time was decreased with increasing oxygen concentration, while the flame was observed only on the upper section of the pellet. Both increasing flow temperature and flow rate could increase the length of volatile flame, but increasing gas flow oxygen concentration shortened that.

Graphical Abstract

KEYWORDS:

• Coal Gangue
• Ignition Mechanism
• Gas Flow Conditions
• Combustion Process
• O₂/Co₂ Atmosphere

Highlight

• The ignition characteristics and combustion processes of coal gangue pellet in O₂/CO₂ atmosphere with drop tube furnace were designed and constructed.

• Three kinds of ignition phenomena of pellet and the transformation mechanism and conditions of these ignition modes were observed.

• Ignition delay and internal ignition temperature of the pellet changing with the oxygen concentration were discussed.

• The burnout time and combustion characteristics of volatile were studied.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [No. 51376171].