Kinetic investigation of the thermal decomposition of CH_4 by direct irradiation of a vortex-flow laden with carbon particles

摘要

The kinetics of the thermal decomposition of CH_4 for co-producing H_2 and carbon black are examined for a vortex flow confined to a cavity receiver and directly exposed to mean radiative power fluxes of 2500 kW/m~2. The CH_4 flow is laden with carbon particles that serve as radiant absorbers and nucleation sites. The temperature dependence of the reaction rate can be described by the Arrhenius law with an apparent activation energy in the range 147-162 kJ/mol and a frequency factor in the range 1.07 x 10~6-7.54 x 10~6 s~(-1), assuming a first-order decay rate law and either a mixed flow or a plug flow reactor model. Based on the latter model, a residence time of 0.3 s is required for obtaining 90% chemical conversion at 1500 K.