Session: 1.1.1 - Fuels, Combustion & Material Handling

Paper Number: 108750

108750 - Thermochemical Conversion of Cow Manure With Different Heating Rates 

Cow Manure, excreta of bovine animal, is bioresource on our planet that is available and cheap. Over the centuries, it was commonly used in many countries as fuel source after being dried.  Thermochemical conversion is one the pathways that has been used for now to convert animals’ manure into useful energy as an alternative clean energy to fossil fuels. Thermochemical conversion includes combustion, pyrolysis, liquefaction, and gasification. The Differential Thermal Gravimetry (DTG) apparatus, located at Global Water Center, Wisconsin, is used simultaneously to perform Differential Thermal Analysis (DTA) and Thermogravimetric (TGA). This paper investigates the chemical kinetics for two major thermochemical conversion processes, pyrolysis, and gasification, of cow manure at different heating rates. Extent of reaction, rate extent of reaction and differential thermal analysis are included in this study. Nitrogen is used for pyrolysis while Air and carbon dioxide are used for gasification. For each process, eight heating rates are studied, 5-40 ^oC/min with 5 ^oC/min incremental. Exothermic reactions were obtained when using nitrogen and air as gas agents while endothermic reaction was obtained in case of carbon dioxide. Exothermic reaction is always preferable over the endothermic one because it is self-sustainable and does not need any external heat source for reaction continuity. Like most of the animal’s manure, cow manure consists of three main components: Hemicellulose, cellulose, and Lignin.  For the pyrolysis process, 5 and 10^oC/min show the most stable exothermic reaction to compared to all other cases however the 10^oC/min is recommended since it is faster which means less time and less energy supplied. In this case, the hemicellulose is broken 321^oC. Increasing the heat rate shifts this phenomenon to higher temperatures, 360^oC for 35^oC/min. With the same concept, the cellulose takes place at 475^oC and around 500^oC for all other heat rates. Finally, the lignin thermal degradation occurred at 760^oC. Air Gasification follows the same structure, partial combustion, the 5^o C/min achieves a stable exothermic reaction while other cases have a rapid exothermic reaction. Two main reasons are behind this irregularity. The first reason is the delay of the device's response to the fast increase in heating rate.  The second reason is the lake of time for the reaction to be completed before the increase in heat rate. This observation is found in all energy carriers. For CO2 Gasification, all the heat rates used to lead to an endothermic reaction which means that the chemical reaction is not self-sustainable and requires more energy compared to air gasification.

Presenting Author: Mohamed Maache University of Wisconsin-Milwaukee

Presenting Author Biography: Research Assistant