Laboratory studies of the pyrolysis of organic wastes for obtaining useful products

Abstract

This work investigated the influence of different set-point temperatures from 550 °C to 950 °C on the performance of the pyrolysis process of mesocarp oil palm fibre (OPF). The experiments were performed in a fixed bed reactor with a length of 780 mm and an inner diameter of 97 mm, with a split furnace; the temperature difference between the experiments was 100 °C. For all the experiments, the heating rate was set to 20 °C⋅min-1 and the fixed N2 flow rate of 2.463 g⋅min-1 was used. To assess pyrolysis performance, the yields of each phase were determined and its products were characterized. The results show, that the char yield slightly decreased with the increase of temperature, while the liquid yield had its maximum at a set-point temperature of 850 °C. The gas yield was calculated by mass difference. The higher heating value (HHV) of the char and the liquid was nearly constant around 28 MJ⋅kg-1, and only in the liquid phase the value dropped at a set-point temperature of 850 °C. The HHV of the gas phase increased with rising temperature and the maximum obtained value was 2.2 MJ⋅(Nm3)-1. Regarding char properties, with increasing temperature, the fixed carbon content in the char increased until a temperature of 850 °C, and its maximum was 79 %. Its ash content was constant around 12 % for all experiments. The bio-oil may have several compounds in its composition like carboxylic acid, ketones, aldehydes, alcohols, aromatic, acyl and alkoxy groups that were determined by FTIR. In the gas composition the production of H2 increased more than six times along the tested temperatures, with a maximum value of 10.96 mol⋅(kg OPF)-1, at the highest tested temperature. The CO production increased rapidly with increasing temperature as well. For the CO and CH4 production the increase was not as high. This work shows that products obtained from the OPF pyrolysis can be used as energy sources and for obtaining chemicals.