The Characteristics Of Rotary Kiln And The Co-pyrolysis Investigation Of Coal/biomass Blends In Rotary Kiln

As the increasing shortage of fossil fuels and environment pollutions,biomass take much attention since it is renewable and clean.Co-pyrolysis of biomass with coal are widely investigated because high hydrogen and alkali in biomass may upgrade the quality of liquid products during coal pyrolysis.However,most co-pyrolysis investigations are conducted in fixed-bed reactors and drop-tube reactors.It is necessary to take the pilot scale test for co-pyrolysis of biomass with coal.Compared with other type reactors,rotary kilns have advantages of large processing capacity,adjustable residence time,high mass and heat transfer efficiency.Consequently,they are widely applied in solid such as tires and fossil fuels pyrolysis.Residence time played an important role in pyrolysis process since shorter residence times leads to incomplete reactions while longer residence times may vary the pyrolysis products and result in extra energy costs.Consequently,measuring the residence time distribution in rotary kiln and studying the influential factors are vital for its application.Additionally,modeling mean residence time were necessary for designing and operating in rotary kilns.A simple step-change method was developed in our research.Two sizes(1.25~2mm,3~3.75mm)of sands were applied as the raw materials and the salts was applied as the tracer.The residence time distribution can be get by determining the salinity of the mixtures in the exit.The influence factors of residence time distribution and mean residence time such as inclination,rotational speed and size were studied.Furthermore,a predictive model for rotary kilns at low inclination was set up since large deviation was found between experimental results and previous models.The results were applied in pyrolysis research and the influence of solid residence time on coal pyrolysis process was studied.The optimum residence time was get at 3°incline and 2rpm.It was applied in co-pyrolysis of biomass with coal and the experimental results were compared with additive models to investigate the synergistic effects.Furthermore,the influence of biomass blending ratio on synergistic effects are investigated and 50% biomass ratio was found to exhibit most devotions between experimental and predicted liquid product yield.