Research Of Caking Property Destruction And Pyrolysis Of Low-rank Caking Coal To Producing High Quality Oil And Gas

Low-rank caking coal is an important energy resource.It is a type of coal between low-rank non-caking coal and coking coal.It accounts for about 29%of my country's coal,a large proportion.Due to its caking,this kind of coal will undergo violent expansion,agglomeration and wall sticking during its high-value utilization(gasification,liquefaction and pyrolysis),which will seriously affect the safety of the reactor.At present,only a small part of this type of coal is used for combustion,and most of it is in an untreated accumulation state.Both waste resources and pollute the environment.The rational use of low-rank caking coal will create huge economic value and social benefits for the society.Aiming at the above-mentioned problems of high-value utilization of low-rank caking coal,this paper establishes pyrolysis technology coupled with caking property destruction,which enriches the research on caking property destruction and pyrolysis of low-rank caking coal in my country.The main research results as follows:1)Low-temperature air oxidation was used to caking property destruction and pyrolysis of low-rank caking coal,and the effects of temperature and atmosphere on the caking of low-rank caking coal were investigated,as well as the pyrolysis of coal sample tar and pyrolysis gas after pretreatment.The quality of the coal sample is analyzed by physical property analysis(Proximate analysis,Ultimate analysis and Caking index analysis),infrared analysis and specific surface area and pore size analysis to characterize its impact on the coal sample's caking,as well as through GC-MS,simulated distillation and GC to characterize the quality of pyrolysis tar and pyrolysis gas.The results show that increasing the pretreatment temperature is conducive to reducing the caking performance of low-rank caking coal.The content of 5-ring compounds in pyrolysis tar is continuously reduced to 0.00%,the yield of light oil continued to increase,a relative increase of 141.46%,and the yield of heavy oil continued to decline,a relative decrease of 15.33%and the CO₂content in the pyrolysis gas decreased by 29.55%.This shows that pretreatment of coal samples is beneficial to improve the quality of pyrolysis tar and pyrolysis gas.2)Low-temperature catalytic oxidation of K₂CO₃ was used to caking property destruction and pyrolysis of low-rank caking coal.The influence of catalyst K₂CO₃concentration and reaction time on the caking of low-rank caking coal and the final temperature of pyrolysis on low-rank caking coal were investigated.The characteristics of low-rank caking coal's caking performance were analyzed by XRF and XRD,and the pyrolysis tar and pyrolysis gas were analyzed by GC-MS,simulated distillation and GC characterization.The results show that increasing the catalyst K₂CO₃concentration,reaction time and reaction temperature are conducive to caking property destruction of low-rank caking coal;increasing the pyrolysis temperature reduces the yield of pyrolysis char,and the yield of pyrolysis tar first increases and then decreases.The maximum value reached at 500?was 8.66%.Between 500?and 800?,the yield of heavy tar dropped from 4.02%to 3.30%,a relative decrease of 17.77%,and the content of light components continued to increase from 53.59%to 57.61%.The relative increase of 7.50%,the pyrolysis gas yield increased from 1.67%to 16.03%,and the CO₂yield in the total gas continued to decline,from 60.67%to 7.91%,a relative decrease of 86.96%,which indicates that the pyrolysis products improved quality is conducive to the high-value utilization of low-rank caking coal.3)Using composite catalysts K₂CO₃ and CaO(K&Ca) low-temperature catalytic oxidation to caking property destruction and pyrolysis of low-rank caking coal.The influence of different catalyst dosages on the caking of low-rank caking coal was investigated.The influence of the pyrolysis kinetics of low-rank caking coal and the influence of the heating rate of different temperature sections on the pyrolysis behavior,and the pyrolysis products were characterized and analyzed by SEM,GC-MS,simulated distillation and GC.The results show that increasing the mass fraction of catalyst Ca O is beneficial to caking property destruction of low-rank caking coal;between 426?and 470?,the pyrolysis activation energies of Rawcoal,Ca and K&Ca are 39.17 k J/mol and 35.96 k J/mol and 27.01 k J/mol,respectively.it shows that adding the composite catalyst K&Ca to Rawcoal is beneficial to reduce the activation energy of the pyrolysis reaction and promote the progress of the pyrolysis reaction,that is,the release of volatiles;at 500??700?,increase the temperature rate,pyrolysis char yield,furan compound content and combustible gas yield(H₂,CH₄,CO and C2+)increase,pyrolysis tar yield,pyrolysis gas yield,asphalt fraction content,phenolic compound content decrease.