Study On The Pyrolysis And Product Characteristics Of Biomass Under Different Atmospheres

China is rich in biomass resources,and produces a large amount of waste biomass in agriculture,forestry,animal husbandry and life every year.The use of thermal cracking technology can realize the efficient use of these biomass energy,and is also an effective way to solve the comprehensive utilization of agricultural wastes such as straw,it can also alleviate the fossil energy crisis and solve environmental pollution.Under low oxygen(anaerobic)and a certain temperature and heating rate(slow and fast),biomass undergoes a series of thermochemical reactions to eventually generate gas(cracked gas),liquid(wood vinegar)and solid(biochar)phase product.Slow thermal cracking is dominated by solid-phase products,and the current application of biochar has wide prospects,However,the slow thermal cracking gas-phase products contain volatile organic pollutants,which are harmful to human health.Whether they can be effectively used is the main problem restricting the large-scale production of biochar.In this paper,ten different biomass raw materials of white pine,Pinus sylvestris var.Mongolica,bamboo willow,ginkgo leaf,sycamore leaf,corn stalk,rice straw,rice husk,corn cob and waste mushroom sticks were selected.By controlling the raw material particle size,pyrolysis temperature,Heating rate and carrier gas flow rate,gas phase product yield,light gas components(H2,CH4,CO,CO2)content,higher heating value and energy were studied in the process of slow thermal cracking under inter(high purity argon)and low oxygen atmosphere Conversion efficiency,and detection of volatile organic pollutants in thermal cracked gas.The research results should below:Under inter atmosphere:With the increase of thermal cracking temperature,the yield of 10 kinds of biomass gradually decreases,the yield of liquid phase does not change much,the yield of gas phase gradually increased.The contents of CH4 and CO2 in 10 types of biomass pyrolysis gas decreased with the increase of thermal cracking temperature;except for waste mushroom sticks and ginkgo leaves,the H2 content in all biomass pyrolysis gases increased;The CO content in the pyrolysis gas of white pine,Pinus sylvestris var.mngolica and rice husk decreased with the increase of pyrolysis temperature,and the CO content in the pyrolysis gas of other biomass increased.The higher heating value of different biomass pyrolysis gases vary.The higher heating values of the five biomass pyrolysis gases of white pine,Pinus sylvestris var.Mongolica,Ginkgo biloba,Sycamore leaves,and corncob all reach the maximum at 550?,respectively.17.76,15.57,13.08,17.20 and 17.90 MJ/Nm3.With the increase of heating rate,the three biomasses of white pine,Ginkgo biloba and rice husk reduced the yield of solid phase products,and the yield of liquid and gas phase products did not change much.The contents of H2 and CH4 in the pyrolysis gas of white pine,Ginkgo biloba and rice husk decreased with increasing heating rate,while the contents of CO and CO2 gradually increased.The higher heating value of white pine,Ginkgo biloba and rice husk decreased with the increase of heating rate.As the carrier gas flow rate increases,the CO2 content in the biomass pyrolysis gas gradually decreases,the H2,CH4,and CO content gradually increase,and finally tends to be flat.As the particle size of raw materials decreases,the yield of gas phase products of white pine gradually increases,the yields of liquid and solid phase products change little,and the yields of liquid and solid phase products of white pine and rice husks change little.Under the same particle size,the higher heating value of white pine is greater than that of rice husk.Under a low-oxygen atmosphere:with the increase of pyrolysis temperature,the solid phase yields gradually decreased,and the gas phase and liquid phase yields gradually increased.The contents of H2 and CH4 in ten types of biomass pyrolysis gas gradually increased with the increase of pyrolysis temperature,while the contents of CO and CO2 gradually decreased.The higher heating value of 10 biomass pyrolysis gases all increase with the increase of pyrolysis temperature,from 6.2 MJ/Nm3 to 17.99 MJ/Nm3.The energy conversion efficiency of all ten biomass pyrolysis gases increases As the pyrolysis temperature increases,at 550?,only 4.00%-9.22%of the energy is retained in the pyrolysis gas,while at 750?,8.15%-24.41%of the energy is retained in the heat cracked gas.As the heating rate increases,the solid-phase products gradually decrease,the liquid-phase products gradually increase,and the gas-phase products gradually decrease.With the increase of heatiog rate,the content of H2,CH4,CO,CO2 is not obvious.The higher heating value of white pine increased with the increase of heating rate,from 12.53 MJ/Nm3 to 15.25 MJ/Nm3,but the high calorific value of the two biomass pyrolysis gases,corn stover and rice husk,gradually decreased.The gas energy conversion efficiency of white pine increased with the increase of the heating rate,from 7.91%to 11.90%;the gas energy conversion efficiency of corn stalks gradually decreased,from 8.12%to 5.61%;the gas energy conversion of rice husk The efficiency increases first and then decreases.Using thermal desorption-GC/MS full scan mode,the pyrolysis gas of pinus sylvestris var.mongolica at 650? was qualitatively analyzed.A total of 17 compounds were detected.Except for nitrogen and carbon dioxide,the remaining components were organic hydrocarbon(alkanes,alkenes,alfynes)hlow-carbon ketones,low-carbon aldehydes,of which organic hydrocarbons are the main components.