Study On Synergistic Effect Of Co-Pyrolysis From Municipal Solid Waste And Rice Husk Gasification Tar

Municipal solid waste（MSW）is the most common household waste,and its random discharge will cause serious pollution to the atmosphere,underground water,soil and so on.At the same time,China has a large quantity of agricultural and forestry biomass resources.Pyrolysis gasification is a common method to effectively utilize biomass to obtain clean energy,but it will produce a large number of tar wastes in the process of utilization.MSW and gasification tar wastes have the characteristics of large carbon content and high heating value,which has the potential of energy utilization.In this research,MSW and rice husk gasification tar were used as raw materials,the response surface method and small pyrolysis device were used to carry out co-pyrolysis experiments.The influences of three factors of co-pyrolysis（pyrolysis temperature,residence time and tar percentage）on the yield and properties of pyrolysis products（biochar,bio-oil and pyrolysis gas）were explored.The interactions between raw materials during co-pyrolysis were analyzed.The fitting equation and three-dimensional relationship model between the product properties and the three factors of co-pyrolysis were established,and the optimal experimental conditions for the yield or properties of the target products were determined.The research results will provide data basis and theoretical basis for the effective utilization of MSW and biomass gasification tar.（1）Research on biochar from co-pyrolysis of MSW and rice husk gasification tar.Biochar was prepared by co-pyrolysis of rice husk gasification tar and simulated MSW.Response surface methodology was used to study the influence of three factors（pyrolysis temperature:400–800°C,residence time:5–30 min,tar percentage:0–100 wt.%）of co-pyrolysis on the yield and quality of biochar.The results showed that under the conditions of 600°C,17.5 min and tar percentage of 50%,the experimental yield,fixed carbon content and HHV of biochar were 2.06 wt.%,3.3 wt.%and 1.08 MJ/kg higher than the theoretical value respectively.Therefore,there is synergistic effect in the co-pyrolysis process of MSW and tar.The molten plastic waste is wrapped around the surface of the raw material particles,and the porous structure of the biochar is blocked,thus inhibiting the release of volatile gases.These three factors have different effects on the performance of biochar.The tar percentage has the greatest impact on the HHV of biochar,while the pyrolysis temperature plays a major role in determining the fixed carbon content of biochar.By establishing the model and fitting equation of biochar and co-pyrolysis factors,the biochar yield and HHV were optimized and verified,and the relationship between biochar yield and properties and co-pyrolysis factors was obtained.（2）Research on pyrolysis gas from co-pyrolysis of MSW and rice husk gasification tar.The composition and properties of pyrolysis gas from co-pyrolysis products were studied.The results showed that under the conditions of 600°C,17.5 min and tar percentage of 50%,the total yield of pyrolysis gas was 1.74 wt.%higher than the theoretical value.Among the pyrolysis gas components,CO yield increased the most,followed by CH₄ and C_nH_m yield,and CO₂ and H₂ yield remained unchanged.Among the three factors,the pyrolysis temperature has the greatest influence on the total pyrolysis gas yield and yields of CO,CH₄ and H₂,while the tar percentage has the greatest influence on HHV,and the residence time has the greatest influence on the Cn Hm yield.For the total HHV of pyrolysis gas,the sum of the energy contribution rates of CH₄ and C_nH_m has always been above 77%,and these two gases are the main sources of total energy of pyrolysis gas.By establishing the fitting model equation between the three factors of co-pyrolysis and the total yield of pyrolysis gas,gas component yield and HHV,the optimization and verification experiments of pyrolysis gas composition and HHV are carried out,which provides data basis for regulating the gas composition of pyrolysis gas.（3）Research on bio-oil from co-pyrolysis of MSW and rice husk gasification tar.The yield and HHV of bio-oil from co-pyrolysis products were studied and analyzed.The results showed that under the conditions of 600°C,17.5 min and tar percentage of 50%,the experimental yield and C content of bio-oil decreased slightly compared with the theoretical value,but the H content of bio-oil increased compared with the theoretical value.In the three factors of co-pyrolysis,the increase of tar percentage has a positive impact on bio-oil yield,C content and HHV.By establishing the fitting model equation of co-pyrolysis three factors with bio-oil yield and HHV,the optimization and verification experiments of bio-oil yield and HHV were carried out.The optimized experimental conditions showed that for bio-oil to have high yield,the pyrolysis temperature was close to 604°C,the residence time was 5 min,and the tar percentage was close to 96 wt.%.For bio-oil to have high HHV,the pyrolysis temperature is close to 684°C,residence time is close to 5 min,and tar percentage is close to 93 wt.%.