Assessment of Chopped Corn Straw Lengths for Combustion in a Fixed Bed Using a Numerical Model

Abstract

In this paper, both a numerical model and an experimental study were developed to determine the important parameters of corn length for combustion behavior in a fixed-bed reactor. As an important factor impacting thermal conversion, changes in the burning rate follow variations in corn length, which then affect gas emissions. As a result of insufficient knowledge concerning the mechanisms of complex combustion, the development of a combustion system has been restricted. Modeling of this combustion system will complement experimental data; however, improving such a model is challenging as a result of the unique characteristics of corn, such as its moisture content and porosity. The results show that corn straw with a shorter length has a shorter ignition time, increased bed temperature, and reduced amounts of unburned carbon in the ash residues. Furthermore, the burning of shorter corn straw causes high emission concentrations from pyrolysis products, such as CH 4 , CO, and most prevalently NO, near the grate, which indicates the beginning of the char oxidation stage. Corn straw with longer lengths increases the difficulty of accurately modeling the irregular shape of corn straw particles for theoretical calculations. In addition, in an actual bed, local bed structures that have not been uniformly mixed result in uncertainties in the flame propagation as well as the time at which the fuel is ignited. The application of numerical modeling allows for a more detailed description of the corn combustion process and can be used as a reference to develop biomass combustion in a large system.

Nitric oxide emissions and temperature evolution during the char grate‐fired process

“…A one‐dimensional fixed bed is most commonly used in research for industrial boilers and the grate‐fired process . To determine the NO emission control factors, the char grate‐fired process was studied in a small‐scale one‐dimensional fixed‐bed system by adjusting the char/O 2 ratio.…”

Properties of densified solid biofuels in relation to chemical composition, moisture content, and bulk density of the biomass

“…The acceptable level of global greenhouse gas emissions should be 50 to 55% below 1990 levels in 2050 to reach the 400 ppm target (Adger 2006). One of the parameters that affects gas emissions is particle size; the combustion of small particles will result in the lower level of gas emissions (Meng et al 2018).…”