Pyrolytic conversion of agricultural residue using continuous auger reactor for resource recovery

In this research work, agricultural residue was pyrolytically converted in a continuous semi pilot auger reactor. Studies have been carried out with variation in operating conditions such as temperature, and its effect on product yield and quality has been analyzed comprehensively. It was found that with increase in temperature from 400 to 500 degrees C, the oil yield increased; however, reduced on further increasing the temperature. The char yield decreased from 50 to 20 wt% and gas yield increased with rising temperature. For cotton stalk pyrolysis, maximum biochar yield of 51% was obtained at 400 degrees C, whereas maximum bio-oil yield of 46.5% was obtained at 500 degrees C. Maximum gas yield of 55% was obtained with mustard husk feedstock at 700 degrees C temperature. Water content of the cotton stalk bio-oil (35%) was found to be lower than mustard husk bio-oil (79%). The water content in bio-oil was found to enhance with increase in temperature. GC-MS analysis confirmed that different chemical value compounds are present in the bio-oils obtained from both cotton stalk and mustard husk. In addition, the chars obtained had a calorific value of 24.15 MJ/kg for cotton stalk and 24.57 MJ/kg for mustard husk. At 500 degrees C, biochar showed good thermal stability in TGA analysis and major weight loss occurred in the temperature range of 500-600 degrees C. It was also observed that biochar contains high amount of micronutrients and can be used for improving crop productivity by partially replacing synthetic fertilizers.