Pyrolysis of wheat straw pellets in a pilot-scale reactor: Effect of temperature and residence time

Pyrolysis of two types of pellets (T1: 100% wheat straw, and T2: 70% wheat straw; 10% sawdust, 10% biochar, and 10% bentonite clay) was performed in a pilot-scale reactor under a nitrogen environment at 20 degrees C to 700 degrees C. This was to investigate slow pyrolysis yields and gas composition as a function of temperature and residence time. The experimental data were obtained between 300 degrees C and 600 degrees C, with a residence time of 90 min, a nitrogen flow rate of 50 cm3/min, and a heating rate of 20 degrees C/min. The results indicated that the maximum pyrolysis temperature is 605 degrees C with a residence time of 55 min. The product analysis showed that the proportion of gas was higher than that of biochar and bio-oil. The conversion efficiency increased with higher temperatures and varied between 66% and 76%. The results showed that carbon dioxide was the main component in the produced gas, and the maximum gas concentration was 63.6% at 300 degrees C for T1. The higher temperature and longer residence time increased the syngas (CO + H2) composition for both T1 and T2 treatments. Nevertheless, the produced biochar had a high carbon content and retained a high calorific value, indicating slow pyrolysis is the ideal utilization route of wheat straw pellet biomass for biochar. A potential method for converting biomass to bioenergy is through pyrolysis. image