Kinetics investigation on the combustion of waste capsicum stalks in Western China using thermogravimetric analysis

Abstract

The combustion kinetics of waste capsicum stalk (WCS) in Western China is investigated through thermogravimetric analysis compared with sawdust and coal, and co-combustion of WCS with coal is also investigated. Results show that the ignition characteristics of WCS is better than that of sawdust and coal, and the activation energy E of WCS-volatile combustion and WCS-char combustion are 78.55 kJ mol⁻¹ and 44.59 kJ mol⁻¹. However, integrating the characteristics of ignition and burnout, the combustion characteristic factor (S _N) of WCS is lower than that of sawdust. With the increasing in the heating rate, the ignition of WCS is delayed. Oxygen concentration $C_{{{\text{O}}_{2} }}$ affects E and k ₀ of volatile combustion largely under rich-oxygen condition, when $C_{{{\text{O}}_{2} }}$ increases from 0.2 to 0.8, E has increased threefold and k ₀ also intensively increases from 10⁶ to 10¹³–10²². Oppositely, effect of $C_{{{\text{O}}_{2} }}$ on the E and k ₀ of char combustion is little, and there is an exponential relationship $S_{\text{N}} = 7. 1 2 8 \times 10^{ - 9} \times { \exp }(C_{{{\text{O}}_{2} }} /0. 3 6 8) - 6. 1 2 6 \times 10^{ - 9}$ between S _N and $C_{{{\text{O}}_{2} }}$. For the tests of co-combustion, all the experimental and weighted-average curves coincide well, and there is no remarkable synergistic effect. With the increase of mixing ratio that WCS added, E and k ₀ of volatile combustion increase, but correspondingly E and k ₀ of char combustion decrease.