Study On Pyrolysis Characteristics Of Oil Shale And Spent Mushroom Substrate And Catalytic Effect During Their Co-pyrolysis

Energy has important impacts on the survival of human,development of the society and security of the country.All countries in the world have to find other energy resources to alleviate energy crisis.Oil shale,as the one of petroleum supplementary resources,can produce shale oil via the pyrolysis,which is of great significance for alleviating the contradiction between energy supply and demand and promoting development of the society.At present,how to increase the yield of shale oil is still the main focus.In addition,the pyrolysis utilization of biomass resources has attracted the attention of the world due to its characteristics of renewability,variety and geographically ubiquitous.China is the main producer of the edible mushrooms in the world,and produces a large number of spent mushroom substrates(SMS)every year.These wastes will bring serious environmental pollutions if it is not effectively processed.Therefore,the work on the pyrolysis utilization of the SMS and its co-pyrolysis behavior with oil shale is of great significance for increasing the reutilization value of biomass wastes and the yield of shale oil.In this paper,oil shale and spent mushroom substrate were used as experimental materials.The aims of this paper were to achieve comprehensive utilization of the SMS and increase oil yield.The pyrolysis behaviors of oil shale and the SMS and their co-pyrolysis behavior were studied,the products yields produced by the pyrolysis alone/co-pyrolysis of oil shale and the SMS were discussed,the catalytic effect of alkali metal salts on pyrolysis of oil shale was studied and the characteristics of the oils were analyzed.Moreover,the utilization of oil shale semi-coke(OSS)in the pyrolysis of the SMS was also studied.The main work of this paper is as follows:1.The pyrolysis behavior of Huadian oil shale was studied by using thermogravimetric analysis method and the Coats-Redfern model,and influences of hydrothermal pretreatment on pyrolysis behavior of oil shale were discussed,the effects of pyrolysis temperature,hydrothermal pretreatment temperature and time on products yields were discussed,and analyzed the characteristics of shale oil produced by the pyrolysis of oil shale after hydrothermal pretreatment.The results showed that the thermal decomposition process of oil shale mainly occurred at 350-520℃.Hydrothermal pretreatment process influenced the structure and characteristics of oil shale,which led to the reduction of the apparent activation energy and caused the decomposition process of oil shale occurred at low temperature zone.The optimal hydrothermal pretreatment temperature was 200℃ and the time was 2.0h.Moreover,hydrothermal pretreatment process caused the contents of elements and compounds in the oil.2.The pyrolysis behavior of the SMS was studied by using thermogravimetric analysis method and the influences of the heating rate on pyrolysis behavior of the SMS were discussed,the effects of pyrolysis temperature and the feeding rate on products yields were discussed,and the characteristics of bio-oil were also analyzed.The results showed that the thermal decomposition process of the SMS mainly included four stages,the decomposition process of hemicellulose and cellulose was the main pyrolysis stagte.The increase of the heating rate could increase the values of the relative pyrolysis parameters.Comparing with other biomasses,it was found that the activation energy of SMS was lower.The optimal pyrolysis temperature of the SMS was 470℃ and the feeding rate was 0.63g/min.The obtained bio-oil had high heating value,and could be used as the synthetic fuel or chemical feedstock.3.The inorganic minerals and metal elements in the oil shale and the SMS were studied by using X ray diffraction and energy spectrum analysis method,the catalytic effect during their co-pyrolysis were discussed,the influences of pyrolysis temperature,the mixing ratio on products yields were studied,and the characteristics of oil were also studied.The results showed that there were obvious catalytic effects existed during their co-pyrolysis,the addition of the SMS significantly improved the pyrolysis characteristics of oil shale.The metal elements in the SMS had significant influence on the catalytic pyrolysis of oil shale.The optimal mass fraction of the SMS in the blended sample was 50%.The addition of the SMS produced some influences on the characteristics of the oil.4.The catalytic effects of three alkali metal salts(LiCl,NaCl and KCl)on the pyrolysis of oil shale were studied,the influences of the proportion of sodium salt on products yields were discussed,the pyrolysis behaviors of oil shale loaded Na Cl and KCl were discussed,and analyzed the characteristics of shale oil.The results showed that the addition of alkali metal salts significantly affected products yields.The optimal mass fraction of the NaCl was 1.5%,and the oil yield was 22.27 wt.%.Oil shale loaded NaCl and KCl promoted the decomposition of oil shale,leading to the formation of more volatiles.The alkali metal salts improved the characteristics of the oil and produced some influences on the content of chemical compounds.5.The pyrolysis behavior of the OSS and its co-pyrolysis behavior with the SMS were studied,the influences of the OSS mass fraction in the mixture on products yields were discussed,and the characteristics of the obtained oils were also studied.The results showed that the addition of the OSS produced catalytic effect during their co-pyrolysis,which increased the oil yield.The optimal OSS/SMS mixing ratio was 1:1.Moreover,the addition of the OSS led to the formation of more aliphatics and aromatic compounds and increased the amount of alcohols in oil.Therefore,the OSS had potential utilization value.