Mathematical Simulation Of Reactive Distillation Of F-T Wax Hydrocracking

The F-T synthesis product has little sulfur, little nitrogen, little aromatic hydrocarbon and very good combustion characteristic. But due to the restriction of Anderson-Schultz-Flory rule, the F-T synthesis product can not be directly used as a pure and high-concentration component. Therefore, hydrocracking has become an important process to overcome this disadvantage. By building mathematical models of isothermal fixed-bed reactor, distillation column and reactive distillation process, the research content and simulation result are listed as follows:Mathematical model of isothermal fixed-bed reactor is built. By combining kinetic equations compiled by Fortran software, physical property equations brought by Aspen Plus and reactor module Rplug, the calculation platform for hydrocracking process is formulated. On the basis of such comparison,9-lumped kinetic model are chosen as the one to insert into mathematical model for sensitivity analysis of isothermal fixed-bed reactor, with the result showing:T= 375℃, P= 4.7MPa, H/O= 0.105wt/wt, WHSV= 2 h-1. Under such optimized operational conditions, distillation process is developed by using reactor’s outlet products as inlet feed. Results show wax conversion rate is 58.0% and diesel selectivity is 20.0%.With the reference of reactor mathematical model, mathematical model of reactive distillation process is built. Under the same parameters according to distillation process, results are gained with wax conversion rate being 60%, diesel selectivity being 80.2% and heat duty of reboiler being decreased by 50%. Based on such result, the design and operational parameters of reactive distillation column are further optimized with the result of optimal reflux ratio being 1.8, condenser temperature being 30℃, stage numbers being 27, reactive stages being 13, distillation stages being 12, feed temperature being 330℃, H/O being 0.105wt/wt, pressure being 4.7MPa.Based on above investigation, mathematical model of reactive distillation process is further improved with multi-feed streams, side extraction and bottom unconverted wax recycling implemented under the development of equivalent simulation processes. The 3 proposals respectively increase diesel selectivity by 4.36%,9.78% and 9.79%. The total heat duty of reboiler is down by 2.55%.