High temperature pyrolysis of composite wastes for syngas production

Abstract

The increasing demand for energy on a global scale has led to the need for alternative energy sources and alternative energy production methods becoming even more important. Among alternative energy sources, waste is one of the most important sources that have come to the fore in recent years. Evaluating wastes with appropriate technologies and obtaining products with high added value are of great importance in terms of sustainability and circular economy. In this study, it was aimed to evaluate composite label wastes and commercial waste pellets in similar content with pyrolysis technology towards syngas generation rich in hydrogen and methane. Composite label wastes were supplied from Frimpeks A.Ş. in rolls. These rolls were cellulosic or plastic materials. The rolls were shredded and pelleted in mixtures with different cellulose-plastic proportions. Secondly, commercial pellets in similar composition were supplied from USA for comparison. Commercial and in-house prepared pellets were characterized with the well-known techniques such as proximate and ultimate analysis, calorimetry, thermal gravimetric analysis, X-ray fluorescence, inductively coupled plasma atomic emission spectroscopy. Pyrolysis tests were performed in both the batch reactor and continuous reactor at pilot scale. Experimental results have shown that that syngas yield was improved at increasing plastic content of the pellets and also with pyrolysis temperature. Moreover, wax formation was observed for plastic containing pellets in batch reactor unit but in a less amount at comparatively high temperatures. On the other hand, wax formation was disappeared for the same pellets pyrolyzed in continuous reactor unit, possibly due to the more extended secondary cracking reactions. When the pellets contained some portion of plastics, higher yields of pyrolysis oil and waxes were obtained depending on the pyrolysis temperature, reactor configuration and reaction mode, batch or continuous. Since the objective of study was to obtain high syngas yields rich in hydrogen and methane, studies were continued over continuous pyrolysis reactor at high pyrolysis temperature, namely at 900 °C. Thanks to the secondary thermal cracking reactions under these conditions, 66% to 76% of the feedstock was converted into pyrolysis gases.