Study And Optimization On CH₄/CO₂ Reforming And Biomass Pyrolysis And Coupling

As one of the most development prospect of industrialization of,biomass pyrolys liquid fuel has been focused by researchers all over the world.However,chemical structure of biomass which is abundant with oxygen functional groups is a kind of oxygen-rich and hydrogendeficient substance,resulting in low bio-oil yield with rich oxygen,which restricts the application of biomass tar.Biomass hydropyrolysis,the combination of external hydrogen and free radical generated by pyrolysis,strengthens stability of free radical to reduce polymerization of free radicals,which could improves bio-oil yield and caloric value.However,realizing the industrialization is obstructed by great economic cost-due to the high price of hydrogen resources.Methane and carbon dioxide reforming may generate active hydrogen atom.Because carbon dioxide is a kind of common green gas and methane is the main component of natural gas and coke-oven gas.Using this two kinds of cheap gases as carrier gas of biomass pyrolysis may not only reduce cost,but also make it more environmental-friendly.Hence,based on using biomass pyrolysis experimental system built by author and with the purpose of improving bio-oil yield and caloric value,this paper studies using the reaction product of methane and carbon dioxide as pyrolysis atmosphere,exploring the effect on biomass pyrolysis oil yield under different reaction conditions and employing optimization function of design module in BoxBehnken Design（BBD）of Design-Expert software to assure the optimum operation condition and then does an experimental verification.The author explores the pyrolysis process of rice and corn straw under CO₂ and CH₄/CO₂ reforming atmosphere on the tube furnace.The results indicate that the combination of CH₄/CO₂ reforming and biomass pyrolysis process may increase bio-oil yield and rice and corn straw present same trend whose bio-oil yield are higher than carbon dioxide atmosphere;pyrolytic water yield under methane and carbon dioxide reforming atmosphere is apparently higher than carbon dioxide atmosphere.With regard to factors influencing biomass pyrolysis oil yield,author explores the optimal condition under different atmospheres,final temperature,heating rate and retention time and experiments were carried out about bio-oil yield under these conditions.The results show that biomass pyrolysis tar yield first increase and then decrease with the increase of temperature,with the maximum yield at 500℃;the higher of heating rate,the more yield of bio-oil;the impact on tar yield is evident with 30 minutes’ retention time while it has noobvious effect on tar yield after 30 minutes.To further explore the impacts of these factors on biomass energy oil yield,the author employs Design-Expert software to do a simulation analysis to obtain the influencing factors,as well as their interaction,of bio-oil yield of rice and corn straw under integration of methane and carbon dioxide atmosphere.The result indicates that the retention time is the most remarkable impacting factor on rice and corn straw bio-oil yield;the interaction between heating rate and retention time during rice pyrolysis is the most striking,while the interaction between final temperature and retention time during corn straw pyrolysis is also remarkable.Author employs Box-Behnken Design（BBD）optimization function of design module in Design-Expert software to explore the optimal condition for the highest bio-oil yield of rice and corn straw under three factors and experiments were carried out to verify the optimization.The results show that the optimal condition of rice for the highest bio-oil yield is presented with final temperature of 524.64℃,heating rate of 64.54℃/min and retention time of 31.35 minutes and with the highest yield of 36.51%,and corn straw with final temperature of 510.95 ℃,heating rating of 56.71℃/min and retention time of 27.31 minutes and with the highest yield of 45.36%.