Integrated Process Of Steam Methane Reforming And Slurry Bed Hydrotreating: Numerical Modeling And Optimization

Vacuum residue is the heaviest and most difficult to process heavy fraction in petroleum fractions and needs to be lightened by hydrotreating.Slurry bed residue hydrotreating technology can achieve higher conversion rate and longer operating cycle,but the complex flow state inside the reactor and the hydrothermal cracking mechanism of the residual oil invalidate the conventional plug flow reactor model.The existing process simulation platform is in the process of hydrogen-hydrogenation coupling process design.In this study,a multi-phase fluid dynamics model was established for the slurry bed reactor,and various factors such as reactor flow field,residual hydrogen thermal cracking process and phase content distribution were systematically investigated,which provided basic data for process simulation;a slurry bed reactor model based on axial diffusion model and a reaction kinetics model were established to simulate the hydrothermal cracking of the slurry bed reactor vacuum residue hydrotreating;based on the established mathematical model,the natural gas steam reforming process of hydrogen production and slurry bed vacuum residue hydrotreating coupling process was established and simulated,and the design and optimization of hydrogen production and hydrogenation process were realized.Based on the multiphase fluid dynamics method,a CFD model of the Euler-Euler multiphase reaction of the slurry bed considering the reaction kinetics of the hydrothermal cracking process of the residue was established.An axial diffusion model was established for the slurry bed reactor,and the rapid calculation of the slurry bed residue oil hydrogenation process was realized under the condition of ensuring the calculation efficiency.The model was further integrated into the process simulation platform to realize the slurry bed vacuum residue hydrotreating simulation of the entire process of oil hydrogenation.Based on the established CFD model of the slurry bed reactor,the laboratory and industrial scale residue hydrotreating slurry bed reactors were simulated respectively.The flow field characteristics in the reactor from 0 to 317 s were systematically investigated.Rate distribution,velocity distribution,and flow field-reaction coupling characteristics.The results show that the flow field distribution of gas-liquid two-phase is consistent when the gas is fully dispersed in the reactor as a bubble;since the liquid phase outlet of the reactor destroys the symmetry of the reactor,with the movement of the internal fluid,the flow field in the reactor gradually changed from the initial symmetrical state to the overall circulation,but had little effect on the residence time.The investigation of the flow field-reaction coupling showed that the flow field distribution and reaction rate distribution in the slurry bed reactor had certain consistency.Based on the established process simulation platform,a hydrogenation-slurry bed residue hydro-coupling process flow for natural gas reforming was established.The reactor size was determined by airspeed,conversion rate and hydrogen consumption.The results of product distribution at different operating temperatures showed that when the operating temperature was at 370~420°C,the conversion ratio of residual oil hydrogenation and operating temperature was close to the proportional relationship,but when at 420~480°C,the temperature change has little effect on the conversion rate.The effect of hydrogen flow rate and purity on the residue hydrogenation process was further investigated.When the membrane area is low and the hydrogen entering the reaction system is insufficient,hydrogen is the decisive factor of the conversion rate of the residue;when the membrane area is increased and the hydrogen is sufficient,the conversion rate of the residue depends on the operating temperature.By optimizing the membrane area ratio,98.3%hydrogen recovery rate and 99.82 mol%hydrogen concentration are achieved,which can fully meet the residue hydrogenation demand.The economic investigation results show that when the operating parameter is Membrane-201area 10,000m~2,the coupling process can reach 81.22%residual oil conversion rate,and the profit of the process is 58,000 RMB/h,which has good economic benefits.