Simulated In-situ Conversion And Pyrolysis Kinetics Of Oil Shale

In this paper,the properties of oil shale from Maoming,Guangdong Province were evaluated,including Fischer assay,proximate analysis,heat value analysis and ultimate analysis.As shown in results,the oil content of Maoming oil shale is 11.15%,providing that it can be refined to obtain shale oil.The content of volatile is 36.38%and the heat value of Maoming oil shale is 9870kJ·kg^-1,so it can be used as fuel.An autoclave was used to simulate oil shale in-situ conversion experiment and the pyrolysates were collected and analyzed.The effects of pyrolysis temperature?constant time and heating rate on yield and properties of pyrolysates were investigated.The results show that increasing pyrolysis temperature and prolonging constant time can promote the kerogen pryolysis to release shale oil.The yield of shale oil increaseed with rising temperature and then decreased after 400?.Because of secondary cracking,The yield of oil will be decreased after 400?.Meanwhile,the yield of pyrolysis gas continue to increase.The heating rate has little effect on the yield of pyrolysates within a certain range,but a larger heating rate will increase the pyrolysis rate of oil shale and increase the yield of shale oil.Pyrolysates obtained under different reaction conditions were analyzed.The results show that increasing pyrolysis temperature and prolonging constant time advisably can contribute to improve the quality of shale oil and the heat value of pyrolysis gas.The content of gasoline and heavy oil fractions in shale oil increased first and then decreased.And the content of diesel fraction decreased first and then increased with rising temperature.The content of saturated fraction and aromatic fraction increased and then decreased,but the content of resin and asphaltene decreased first and then increased.Pyrolysis gas are primarily composed of CO and CO₂,the content of CO and CO₂ begin to decreased with the rising temperature and the prolonging constant,and the content of hydrocarbon gas increased.Therefore,the heat value of pyrosis gas rised.But the change of heating rate has little effect on shale oil properties,gas product composition and heating value under a low heating rate.The thermal experiment on Maoming oil shale was performed at different heating rates of 5,10,15,20 and 25?/min using thermogravimetric analyser.The kinetics parameters were calculated according to thermal data.It is found that the apparent activation energy obtained from integral and differential methods are closed,the results were 116.30 kJ·mol^-1 and 126.30 kJ·mol^-11 respectively.The result calculated using Friedman method shows that the activation energy increased with rising conversion rate,and the plot of InA vs.E for Maiming oil shale becomes a liner line,which is E=18.865+6.694lnA.The value of activation energy using maximum pyrolysis rate method is 169.61kJ·mol^-1.The time needed to finish 95%conversion for Maoming oil shale pyrolysis at the temperature of 500?is about 4.59 minutes.