Study Of Pyrolysis And Combustion Characteristics And Kinetics Of Oil Sludge

Pyrolysis treatment has the characteristics of harmless treatment and easy industrialization.In this paper,the comprehensive analysis of Jihua oil sludge is carried out,including Fischer assay analysis,proximate analysis,ultimate analysis and calorific value test,etc.The basic properties of oil sludge and its pyrolysates were determined,and the results were compared with those obtained by extraction.Through experiments,The pyrolysis and combustion characteristics and kinetics of Jihua oil sludge were studied using thermogravimetric analyzer.The research results of this paper can provide experimental data foundation support for the sludge pyrolysis treatment technology.The oil content of Jihua oil sludge is 14.7%,which has good recovery value.The main components of pyrolysis gas include hydrogen,carbon dioxide,carbon monoxide and hydrocarbon.The volume fraction of hydrogen reaches 48%,which can be separated by membrane separation technology and is used in the hydrogenation process of oil products.The pyrolysis oil is dominated by straight-chain alkanes,and the diesel fraction accounts for 40%,which can be used as raw materials to produce high-quality diesel.Through XRF analysis of semi-coke,it is confirmed that the content of heavy metals and other harmful substances in semi-coke is low,and it can be used as a raw material for the production of ceramic tiles and other products.The pyrolysis process of Jihua oil sludge is mainly divided into two stages.One is the volatilization of organic matter at 150-380℃,and a small amount of reactive heteroatoms is pyrolyzed.The other is pyrolysis process of a small amount of volatile heavy components at 380-550 ℃.The activation energy was calculated using Coats-Redfern model.The activation energy in volatilization stage is about 37 k J/mol,and the activation energy in the pyrolysis stage is about 150-180 k J/mol.The activation energy calculated by the Friedman model in the volatilization stage is about 63-88 k J/mol,and the activation energy in the pyrolysis stage is increased from 127 k J/mol to235 k J/mol.The activation energy calculated by the DAEM model in the volatilization stage is about 61-81 k J/mol,and the activation energy in the pyrolysis stage is increased from 121 to 237 k J/mol.The combustion of Jihua semi-coke is divided into two stages,including combustion of macromolecular organic matter,and combustion of fixed carbon.The maximum temperature of semi-coke combustion is independent of the temperature rise rate.As the heating rate increases,the boundary between semi-coke combustion and fixed carbon combustion is more obvious.The first-stage activation energy calculated by Coats-Redfern model decreased from 150 k J/mol to 115 k J/mol,and the second-stage activation energy about 81-90 k J/mol.The activation energy calculated by the DAEM model firstly increased from 156 k J/mol to 170-205 k J/mol.The combustion of Jihua sludge in first stage is the volatile combustion of small molecular organics.The second stage is the volatile combustion of large molecular organics and pyrolysis combustion,and the diffusion of oxygen into the crucible to produce fixed carbon combustion.The maximum burning rate of dry-based organic matter corresponds to the temperature increasing with increasing heating rate.The first-stage activation energy calculated by Coats-Redfern model is 45-53 k J/mol and the second-stage activation energy increases from 86 k J/mol to 104 k J/mol and then decreases to 74 k J/mol.The first-stage activation energy calculated by DAEM model is62-130 k J/mol,and the second-stage activation energy is 65-79 k J/mol.