Research On The Effect Of Combined Pickling-torrefaction Pretreatment On The Pyrolysis Characteristics Of Millet Straw And Bran

Level to further reveal the two coupled pretreatment on biomass pyrolysis products composition and the effect of this research by millet straw,millet bran,washed millet straw and washed millet bran roasting pretreatment on bran as test material,the torrefaction temperature of 230℃,260℃and 290℃respectively,torrefaction time for 30 minutes,the torrefaction carbocoal produced were collected for Fourier infrared spectrum analysis of the surface functional groups,baking liquid with GC-MS detection component.Again of millet straw,bran,washed millet straw,washed bran and its different torrefaction temperature of carbocoal set up by a total of16 kinds of sample in a fixed bed tube furnace pyrolysis experiments on the pyrolysis reaction platform,occurring in the process of the liquid products were collected for GC-MS detection components,solid product fourier infrared spectrum analysis,and then explore the deashing deoxidization coupled pretreatment on biomass pyrolysis products production rate and organic liquid product components.The content of ash and volatiles in rice straw was lower than that of millet bran,and the content of volatiles was higher than that of millet bran.When the raw materials were pretreated by washing and torrefaction,the volatiles content of the samples decreased,the ash content and fixed carbon content increased,and the calorific value increased.The fixed carbon content and calorific value of millet bran were the highest after pickling and two-stage coupling pretreatment after baking at290℃.The contents of C,O and H of the two raw materials have little difference.Torrefaction pretreatment can significantly reduce the content of element O and increase the content of element C,and with the increase of the degree of torrefaction pretreatment,the influence will be more significant.Compared with single pretreatment,combined pretreatment had significant influence on the content of these three elements,and the influence trend was basically consistent with that of single baking pretreatment.The torrefaction liquid of the two samples is millet in acetic acid,furfural,2,3-dihydrobenzofuran,levoglucose and other components.The relative content of levoglucose in the baking liquid of the pickling sample is much higher than that of the unpickling sample.The absorption peaks in the FTIR spectra of the two raw material samples are similar.The absorption peak did not disappear obviously in the spectra before and after pickling.The FTIR spectra showed the same trend after different curing treatments.The positions of the absorption peaks of some main groups were almostthe same,but the intensity of the absorption peaks was different.Deashing deoxidization joint after preprocessing pyrolysis tar-CH₂stretching vibration characteristic peaks corresponding to the peak,some hemicellulose and cellulose and lignin characteristics of the peak of the peak area of a sharp decline in,show that the sample fracture and form a part of oxygen containing functional groups in the main water,acetic acid and furan baking product liquid and CO and CO₂gas,increase the samples after pretreatment of C/O,then improve the calorific value.After the torrefaction pretreatment,the yield of coke and non-condensable gas generated by the pyrolysis of millet straw and millet bran samples decreased to26.94%and 27.82%respectively,while the yield of bio-oil increased to 45.24%.By analyzing the three-phase yield of biochar pyrolysis of millet bran after washing and torrefaction pretreatment,it can be found that the yield of bio-oil is higher than that of raw materials ofmillet bran during light baking,but with the increase of torrefaction degree,the yield of bio-oil drops sharply.The combination pretreatment with acid washing,ash removal and deoxidation can improve the sugar content of bio-oil and reduce the phenols,acids and furans,thus improving the quality of bio-oil.