Experimental investigation on the destruction rates of organic waste with high moisture content by means of self-sustained smoldering combustion

Self-sustained smoldering has been identified as an effective and efficient treatment for waste with high moisture content. To create the necessary conditions for the propagation of a smoldering reaction through the material, the waste is mixed with an inert material, such as sand, to create a porous matrix. This work shows the effect of different experimental parameters (moisture content, fuel concentration and airflow) on the fuel consumption rate during smoldering experiments under robust conditions. Fuel composition was the same for all experiments conducted. The main observation of these experiments is that the consumption rate remains invariant with the original moisture content of the waste, while showing a linear relationship with fuel concentration and airflow. An expression that describes the fuel consumption rate as a function of both parameters is presented. Based on the experimental observations, a kinetic mechanism analogous to the Eley-Rideal model for gas reactions on the surface of a solid is proposed. Finally, an expression that describes the smoldering front propagation velocity as proportional to the airflow and to the inverse of the density of the sand is presented. This expression is verified by 80 smoldering experiments under a wide range of operating conditions and four reactor sizes. The equation can be utilized for every reactor size, moisture content, fuel concentration and airflow rate, so long the smoldering reaction is robust. (C) 2016 by The Combustion Institute. Published by Elsevier Inc.