| The classification and coupling utilization of coal resource is one of the most advancing clean-utilization technologies of coal,and it also catches the eyes of National Development and Reform Commission.A lot of researches focused on the gasification process of pure coal and the mixture of coal with different types of biomass have been conducted in the last decades.But as for oil shale,one of the most potential non-traditional fossil fuel,there are few researches carried out on the coupling utilization of it with coal.Based on the significant property distinct between coal and oil shale,it is worthy to explore the potential economical and environmental benefit of coupling utilization of coal with oil shale.The detailed understandings of the characteristics of kinetics,gaseous emission and inter-active reactions during the coupling utilization process of coal with oil shale are quite necessary before we are capable to design a suitable system out of them.According to this,in this dis-sertation,we applied the experimental analysis,modeling validation together with numerical simulation to carry out the researches on the follow aspects:1)The possibility of oil shale in the field of efficient-clean utilization of coupling utilization with coal;2)The mechanism of devolatilazition and char gasification processes during coupling utilization of coal and oil shale;3)The application of numerical simulation on the characteristics researches of the coupling uti-lization of coal and oil shale.First,the experiments aimed on getting pyrolysis characteristics and gaseous emission anal-ysis of different types of coals,shale oil and their blends were conducted on the coupling plat-form of TG-FTIR.The pyrolysis process was controlled by the constant heat rate program.The single variable method was applied here to study the effects of the coal type,mixing ratio,etc.on the pyrolysis characteristics and gaseous emission property during coupling pyrolysis.A increased of 1.4%in the yield of gaseous and liquid products was observed in the case which the proportion of oil shale in the blends was 30%.At the same time,in-situ FTIR and KBr-disc technologies were introduced to conduct the analysis of the inorganic and mineral components on the surface of the samples.The selective effect on gaseous products was found during the coupling pyrolysis process between lignite and oil shale by comparison analysis between the experiments values and the calculated ones,since the ratio of aromatic-C-H to aliphatic-C-H increased during coupling pyrolysis.And the inhibition of the overall pollutants emission was also observed during the gaseous emission analysis,and the results were combined with the for-mal researchers' achievements about the input-output model of pyrolysis process to develop a new model to describe the devolatilazition behaviour of blends of coal and oil shale.Then in order to have a better understanding on the coupling pyrolysis process,two model free methods are applied to obtain the values of apparent activation energy of oil shale pyrolysis.The value varies from 210.32 kJ/mol to 268.33 kJ/mol as the conversion rate changes from 0.2 to 0.9.The Malek method was conducted to validate the active energy values.The Sestak Breggren model was determined as the reaction model for oil shale's pyrolysis process.The simulations on the TG experiments were conducted by the integrated model which coupling the single-step pyrolysis model with Lee model(for water evaporation),decomposition model of mineral contents and heterogeneous gasification reaction model for char.The pyrolysis phenomenon was further explained by comparison analysis between the simulation result and the experiments.The further work was to combine the finite volume method with the pyrolysis model which derived from formal work and others models,eg.momentum equation,species transport equa-tions and energy equations,to carry out the numerical simulation of the heat transfer process of the oil shale on a certain lab-scale fix bed.It is for the calibration of the heat and mass transfer models.The program developed here was then updated to a large-scale gasifier to sim-ulate the actual oil shale pyrolysis process.In addition,the effects of the key parameters of the gasification process,the property of fuels,bulk density,carrier-phase velocity and pyrolysis temperature,etc.on the characteristics of heat and mass transfer were studied.In order to get a comprehensive understanding of the coupling utilization of coal and oil shale,other two studies were carried out on the same TG-FTIR platform to specify the influ-ence of the coupling utilization on the other reaction processes.The first study was of the C02 gasification characteristics of nascent pyrolysed particles from coals and oil shale.In this pa-per,we developed a novel method,a four-stage valve-controlled method,to explore the CO2 gasification characteristics of nascent pyrolysed particles.In this part,the effects from the types of fuels,pyrolysis temperature and volatile residues on the coupling gasification process were carefully analysised.The activities of the chars obtained from mixture samples is higher then the individual coal and oil shale.Based on the truth of oil shale's high ash-content,SEM and XRD technologies were applied to conduct the porous and structure analysis of oil shale chars obtained from different pyrolysis temperatures.So the main effects of the temperature on oil shale chars were collected and also contributed to the analysis on the acceleration effect from oil shale chars during the coupling utilization with lignite.For the second study,the oil shale chars were produced separately on a horizontal fixed bed reactor.And then we processed the experiments which mixed the oil shale chars with raw lignite samples.By conducting a set of characterisations,which includes oxygen-containing functional groups on the surface,mineral compositions,inorganic oxides and the content of certain trace elements,on the oil shale chars obtained from different conditions,the physical and chemical properties of them were well stud-ied.The obvious increase in the content of-S=O,-C=O,-CH(both aromatic and aliphatic)and CH4 proved the upgrading of syngas.The potential of the catalytic lignite pyrolysis through oil shale which had higher activities as well as better syngas qualities were validated by the TG analysis and the real-time gaseous emission detection data.At the very end,a integrated solver for solid fuel gasification was developed based on the finite volume method.In order to conduct the validation of the simulation program for solid fuel gasification which was built based on finite volume method,a set of numerical simulations were carried out to simulate the Columbia coal gasification experiments on a small-scale gasify furnace.The predictions results meet well with the experiment data with a relative deviation within the 20%limit and absolute deviation within 4%limit.The sensitive analysis and un-certainties analysis of the model were carried out based on the baseline case.By combining with the coupling pyrolysis model,and other models for describing the homogeneous and cat-alytic heterogeneous reactions,several cases were carried out on this model,to study the fluid field,temperature distribution,gaseous field and other important parameters during the coupling pyrolysis of coal and oil shale.The results shown that this program is capable to give the rea-sonable result to study the characteristic of important variables and also to provide the advice on the operation optimisation.It is also self-developed model friendly,namely by integrating more detailed models into it,the program is capable to give more useful and realistic results to provide the theory guidance in industrial gasifier design and operation optimisation. |
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