Kinetic Study And Simulation Of Trickle Bed Reactor For Hydrorefining Of Full Fraction Coal Tar

Coal tar is the main by-product of coal pyrolysis process.Because it contains high sulfur,nitrogen and other heteroatoms,it is generally used after hydrorefining.At present,the theoretical research on coal tar hydrodesulfurization?HDS?and hydrodenitrogenation?HDN?is still in the exploration stage,especially the research on the complex system of full-distillation coal tar has not been widely reported at home and abroad.In addition,the application of computer simulation technology in the chemical production process is increasing day by day.In order to accurately describe the hydrogenation reaction process of full-distillate coal tar,it is urgent to conduct in-depth research on its reaction kinetics and reactor simulation technology.In this paper,1512 hours hydrofining experiments were carried out in a trickle bed reactor using full fraction coal tar as raw material.The reaction conditions were as follows:pressure 10-14 MPa,liquid hourly space velocity?LHSV?0.2-0.4 h^-1,temperature 613-653K,volume ratio of hydrogen to oil 1000:1.the multi-parameter modified kinetic models were established,respectively.The isothermal laboratory trickle bed reactor model and adiabatic industrial reactor model were established under the gPROMS software platform.The main conclusions are as follows:?1?Nonlinear fitting of HDS and HDN kinetic parameters were carried out.The results were as follows:activation energy 94965 J/mol,98173 J/mol,reaction order 1.5,1.58,catalyst half-life 20140 h,12196 h,respectively.The accuracy verification results show that the model has higher prediction accuracy.?2?In the calculation of the laboratory scale reactor model,the axial variation of each substance in the gas,liquid and solid phases were obtained.It has been found that the presence of hydrogen sulfide doesn't have inhibitory effect on HDS.The influences of reaction condition were as follows:the higher the pressure and temperature,the lower the space velocity,the higher the sulfur and nitrogen removal rate.HDN reaction exhibits a higher catalyst efficiency factor,the pressure has a lower effect on nitrogen removal rate of HDN reaction.?3?In the calculation of the industrial scale reactor model,three design schemes were adopted:equal temperature rise of catalyst bed,equal catalyst bed length,and equal catalyst bed length with different inlet temperatures.By calculating the hydrogen addition,chemical hydrogen consumption.It can be concluded that scheme 1 can realize the optimal configuration of the catalyst bed,but can't meet the reasonable utilization of thermal energy,resulting in higher addition of hydrogen;scheme 2 can't meet the single-stage bed temperature rise requirement,and it is easy to cause hot spots in the catalyst bed;scheme 3can realize self-utilization of reaction heat,and the minimum amount of hydrogen required is 47360.65 Nm³/h.The temperature rise of each beds were 23.74,21.39,12.90,6.42?,sulfur and nitrogen removal rates were 81.65%and 80.36%,respectively.By comparing with the crude oil,it is found that the temperature rise of catalyst bed formed by hydrogenation of coal tar is higher,the number of bed segments required is larger,and the length of the single-stage bed is shorter.