Design And Optimization Of Distillation Separation Processes For Petroleum-based And Coal-based C₉aromatics

C₉ aromatics come from a wide range of sources and contain many products with high added-value,such as mesitylene,methyl-ethyl benzene,trimethylbenzene and other fine chemical raw materials.However,there is a lack of multi-component purification process of C₉aromatics.The development of multi-component separation technology of C₉ aromatics and the improvement of resource utilization rate of C₉aromatics are helpful to promote the development of fine chemical industry and the comprehensive utilization of resources.In this paper,firstly,the main sources and applications of C₉ aromatics are described,and the energy-saving technology of distillation separation is introduced.Secondly,according to the composition characteristics of petroleum-based and coal-based C₉aromatics,the distillation separation sequence was designed,and the binary tree method was used to arrange and combine the isolates.14 kinds of coal-based C₉aromatics and 42 kinds of petroleum-based C₉ aromatics were obtained.The sequence was calculated by using the separation ease coefficient,the relative cost function method and the gas flow rate method to determine the relatively optimal sequence.Finally,the optimized process was strictly calculated by simulation software,and the optimal separation sequence was determined based on the total annual cost（TAC）as the objective.Aiming at the key components of C₉ aromatics,mesitylene and p-methylethyl benzene,the vapor-liquid equilibrium data of binary system under different pressures（10 k Pa,20 k Pa,50 k Pa,101.3 k Pa）were measured by vapor-liquid double-cycle equilibrium kettle.Then three activity coefficient models（NRTL,Wilson,UNIQUAC）are used to fit the experimental data,and the thermodynamic model parameters of the binary system are obtained.Wilson model is more suitable for C₉ aromatic distillation separation calculation.On this basis,according to the optimal sequence of petroleum-based and coal-based C₉ aromatics distillation separation,a simulation flow was established to design the low pressure thermal integration,and atmospheric pressure decompression coupling thermal integration energy saving process.After economic calculation,the low pressure thermal integration process of coal-based C₉ aromatics saves energy by 14.75%and TAC by 11.76%compared with that before thermal integration.The atmospheric pressure decompression coupling thermal integration process saves energy by 34.07%and TAC by 14.58%compared with that before thermal integration.The energy consumption was reduced by 9.02%and TAC by 16.02%in the low-pressure thermal integration process of petroleum-based C₉aromatics.The energy consumption was reduced by 48.9%and TAC by 17.93%in the atmospheric pressure decompression coupling thermal integration process.Finally,the composition and separation products of petroleum-based and coal-based C₉ aromatics are analyzed,and the economic benefits of petroleum-based and coal-based C₉ aromatics separation processes are compared.It is determined that atmospheric pressure decompression coupling thermal integrated distillation separation is more suitable for C₉aromatics separation,and the economic benefits of coal-based C₉aromatics are higher than those of petroleum-based C₉aromatics.