DEVELOPMENT AND IMPROVEMENTS OF THE CONTROLLED ATMOSPHERE PYROLYSIS APPARATUS

Abstract

Previously developed, the Controlled Atmosphere Pyrolysis Apparatus (CAPA) was designed to address the needs of a well-characterized gasification apparatus from which material properties could be derived. Although the data from CAPA has been well-validated through modeling and other various means, only a single functional and published version of the apparatus exists which hinders widespread acceptance. Additional concerns and questions about the design remain which warrants further improvement and investigation. In this work, elements of CAPA are revisited, redesigned, and improved to provide a more defined environment for bench-scale material evaluation. Existing geometrical constraints were maintained to allow for a direct comparison to previous work and confirm previous characterizations. In pursuit of these goals, several improvements were made. Implementation of an integrally water-cooled chamber was accomplished through additive manufacturing, allowing chamber temperatures to remain steady throughout the duration of a test, reducing additional radiant heat flux to the sample. Measurement resolution was increased with an upgraded thermal imaging camera, mass balance, and data acquisition system. Full analysis of the gas temperatures, chamber temperatures, oxygen concentration, and overall thermal environment was performed to replicate previous results and provide quantitative information for use in a pyrolysis modeling. Characterization experiments confirmed that heat flux profiles and gas temperatures are within the experimental uncertainty of both apparatuses. Chamber temperatures were reduced, providing for more clear boundary conditions and simplified modeling. Experimental results of this improved version of CAPA were compared against previous experiments conducted on poly(methyl methacrylate) (PMMA) and oriented strand board (OSB). Mass loss rate and surface temperature data were comparable indicating the apparatus performs as intended. Several problems and concerns were identified in this process for further study. This work provides further confirmation of the usefulness and accuracy of CAPA for use in analyzing the thermal decomposition of materials.