Study On The Separation Process Of High-temperature Fischer-tropsch Synthetic Oil

The Fischer-Tropsch synthesis technology is a method for preparing hydrocarbon organics by using synthesis gas as a raw material.High-temperature Fischer-Tropsch synthetic oil has a narrow carbon number distribution and a high content of linear olefins and alkanes.The components obtained after purification are high-quality raw materials for the preparation of ?-olefins and alkanes.In this paper,the light hydrocarbon,liquid wax and soft wax obtained from high-temperature Fischer-Tropsch synthetic oil are used as raw materials,combined with Aspen Plus simulation and field experiments to study the separation process of high-temperature Fischer-Tropsch synthetic oil.The C6 fraction of light hydrocarbons is divided into model substances,and combined with reactive distillation and extractive distillation to obtain 1-hexene.Using 2-ethyl-1-butene(2E1B)as raw material,ethanol as etherifying agent,D005 acidic cation exchange resin as catalyst,etherification was carried out using high-pressure batch reactor and fixed-bed reactor,studying the thermodynamic and kinetic analysis of synthetic tert-hexyl ethyl ether(THEE3).The conversion and product selectivity at different temperatures(50?80?),space velocity(20?50h-1)and ethanol to olefin ratio(0.5?2)were measured respectively,and finally the etherification of tertiary carbon olefins and ethanol was obtained the experimental equilibrium constant of the reaction and the kinetic rate equation,the test result and the calculated value are basically consistent.Using Aspen Plus to simulate the separation of 1-hexene in C6 fraction,with 1-hexene purity and recovery as the final optimization goals,a three-stage separation process was designed:reactive distillation to remove C6 tertiary carbon olefins;extractive distillation to separate Alkenes and alkanes;solvent recovery and purification of 1-hexene.The mass purity of 1-hexene was 99.7%,and the recovery rate was 99.77%.Combined with the separation requirements of liquid wax and soft wax,a pilot rectification tower was designed.The theoretical calculation results of the parameters such as the selection,diameter,height and pressure drop of the packed column were checked,and selected pilot-scale rectification tower with the 4mm ? Random packing,50mm tower diameter and 5m tower height to meet the processing capacity was determined.The experimental results of separating single-carbon n-alkanes from liquid wax and soft wax using this device show that high-purity single-carbon alkanes can be prepared by liquid wax to meet the separation requirements,and the material balance of each component is conserved;soft wax preparation is high The purity of the monomeric alkane,the carbon number of the target product increases,the product purity decreases,and the material balance of the C20 component is not conserved.The possible reason is that the soft wax component has undergone high temperature dissociated during the distillation process due to the excessive temperature of the tower kettle,and finally influenced product quality.