Conversion of cud and paper waste to biochar using slow pyrolysis process and effects of parameters

A series of laboratory studies were undertaken in Gondar to explore the effects of temperature, air mass flow rate, heating rate, and residence duration on cud and waste paper char yields in slow pyrolysis. Cud and waste paper were burned at a low pyrolysis temperature to generate biochar (167 °C). The rate of decomposition depends on the feedstock and the process conditions. The biochar yield is mostly governed by the applied regulated temperature and airflow rate, according to the data. During the experiment, the main airflow rate delays the pyrolysis process. The temperature rises when both the primary and secondary air inlets open at the same time, resulting in lesser biochar output. The experiment was carried out at a slow pyrolysis temperature of 167 °C, with 15% biomass moisture, 60% humidity, and a 0.35–1.5 kg/s air mass flow rate. At this temperature, 30 kg of feedstock, cup, and paper in the reactor generate 10 kg–23kg and 10–20 kg of biochar, respectively, at a 0.35 m/s airflow rate. As the airflow rate increases within the restricted values, a temperature gradient appears and tends to increase. However, as the pyrolysis temperature and airflow rate rise, the biochar yield decreases. In this study, the effect of parameters on composite char production was investigated.•The effects of primary and secondary air on composite char yield was examined•The maximum temperature of 167 °C was used to produce the char.•Energy exchange in the reactor during char production at maximum air flow rate was analyzed.•11 kg–25 kg of biochar yield was obtained in the reactor from 30 kg of feedstock.•The corresponding air flow rate and temperature was included in the text for every biochar yield result