Pyrolysis of rapeseed stalk: Influence of temperature on product characteristics and economic costs

In this study, the influence of temperature on the pyrolytic product characteristics and economic costs was investigated and an optimum operational temperature was determined. Because of the relatively high contents of CH4 (21 vol%) and H-2 (32 vol%), the low heat value of gas at 750 degrees C reached 17.64 MI/m(3), while the largest yield of gas was achieved at 950 degrees C. The obtained oil could be divided into the following three types in accordance with the temperature change: high acidity oil (250 degrees C-350 degrees C), phenol enriched oil (450 degrees C-650 degrees C), and heavy oil enriched with fused rings (650 degrees C-950 degrees C). The heaviest oil contained fused rings (similar to 50%), phenols (similar to 30%), and acids (similar to 20%), and it showed good stability of ingredients in oil. The largest yield of char was detected below 350 degrees C. To obtain quality smokeless solid fuel and activated char, the operational temperature should be set to 550 degrees C and 750 degrees C, respectively. The results from the economic analysis on biomass pyrolysis using a moving bed reactor suggested that the optimum operation temperature was 650 degrees C and the maximum profit could reach to 25 million yuan per year. (C) 2017 Elsevier Ltd. All rights reserved.