| In order to meet the national standard VI for producing clean diesel,the hydrotreating technology in trickle bed reactor has been commercially applied.However,the studies on its kinetics that will be used in reactor design of scaling up are still insufficient,which makes the evaluation of catalyst in laboratory be difficult to predict the operational performance of industrial reactors.The model design and operation of the reactor is the unique way to build an intelligent refinery.In this regard,this thesis analyses the results obtained from experiments over diesel hydrotreating catalyst in different scales of reactors,and based on the experimental results of highthroughput micro-packed bed reactor,we establish the kinetic model for ultra-deep hydrodesulfurization,hydrodenitrogenation and aromatic saturation.After considering the effects of internal and external diffusions,we establish the reactor model of pilot reactor and compare the values of the simulation and the corresponding experiments.The main researches are as follows:Based on the analysis of the experimental results of high-throughput micro-packed bed reactor,the kinetic models of three-zone and two-zone for hydrotreating of diesel are established according to the division of the sulfur content.The three-zone kinetic model includes the series reactions of aromatics and naphthenes in aromatic saturation except the effects of paraffin;the power-law for the hydrodenitrogenation to describe the accelerated reaction rate around 30-50 ?g/g(ppm)and the inhibition effect of H2 S and nitrogen compounds in hydrodesulfurization in the zone 1 and 2 of the sulfur content ranging more than 10,000 ppm to 2000 ppm and from 2000 ppm to 500 ppm,respectively.Their fitting trends are in agreement with the experimental results except the zone 3 of sulfur content below 500 ppm,where the model does not express the trend of reaction rate from fast to low and there are competitive adsorption between sulfur compounds and other compounds like aromatics.In order to minimize the model parameters in the case of taking into full consideration of all kinds of competitive reactions,the hydrotreating kinetics model of two zones is established based on the research of the three-zone hydrotreating model.The paraffin is added to the series reactions and the inhibition of the DA to the hydrogenation of MA is considered in aromatic saturation.For hydrodenitrogenation,in the view of reaction step,the inhibition of intermediate products is considered in the kinetic model.The hydrodesulfurization reaction is divided into two zones,and the effects of H2 S,nitrogen-containing compounds,aromatic hydrocarbons,and virtually refractory sulfur compounds are involved in the kinetic model.The results of the two-zone model are closer to the experimental results than those of three zone model,and the model parameter values are all within the range reported in the literatures.In spite of the high precision of the fitted experimental data,another important feature of the two-zone model is the ability to accurately describe the full range of changes in sulfur content from above 10,000 ppm to below 10 ppm.In addition,an optimal operation interval of such trickle bed reactor is obtained by using the developed two zone kinetic model.For pilot reactor of larger scale,the effects of internal and external diffusion are introduced into the kinetic model of two zones,and a three-phase mass transfer-reaction model of gas-liquid-solid is established.The results show that the difference of hydrodenitrogenation and aromatic saturation in different reactor scales is small,while that is large in the hydrodesulfurization;the external diffusion has little effect on the hydrotreating of diesel in the pilot reactor while the internal diffusion has a great effect on hydrodesulfurization,especially when the sulfur content is less than 2000 ppm.Additionally,the appropriate operating interval is also optimized out in pilot reactor for producing qualified diesel to meet national standard VI of China. |
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