Study On Optimization And Control Of Isoprene Separation Process By Cracked C5

Cracked C5 resource is an important by-product of naphtha cracking to ethylene.If it can be reasonably utilized,it will not only protect the only earth resources,but also improve the comprehensive competitiveness of China’s ethylene industry.Therefore,it is particularly important for petrochemical enterprises to realize the effective utilization of C5 resources.In addition,isoprene（IP）is the material with the highest added value and the most widely used in cracked C5 resources,and its demand in China also shows an increasing trend year by year.Therefore,how to realize the separation of high-purity IP products efficiently and energy saving has become an important research direction for the comprehensive utilization of C5resources.In order to actively respond to the national"double carbon"policy of energy conservation and emission reduction,combined with the disadvantages of long process,complex process and high energy consumption of the traditional thermal dimerization two-stage extractive distillation process which has realized industrialization in China,this thesis adopts process strengthening means,The steady-state design,multi-objective optimization and dynamic control of thermal coupling process were studied in the raw material pretreatment section and extractive distillation section of cracked C5 to high-purity IP process.For the raw material pretreatment section,based on the reactive distillation technology,this thesis further couples it with the dealkyne tower to form the cracked C5 reactive dividing wall column（RDWC）process,which takes the response surface tool（agent model）as the bridge,MOEA/D multi-objective algorithm（the optimization objectives are total annual cost（TAC）,CO₂emission and cyclopentadiene dimerization selectivity）is used to optimize its structure and operating parameters,so as to realize the trade-off between process economy and environmental protection,and then provide more choices of optimal operating conditions for process personnel.The optimization results show that compared with reactive distillation process,RDWC process can save TAC by 12.3%,reduce CO₂emission by 34.8%,and improve the selectivity.For the extractive distillation section,the conventional extractive distillation column（CEDC）,extractive dividing wall column（EDWC）,extractive dividing wall column with intermediate reboiler（IR-EDWC）and improved differential pressure thermal coupling extractive distillation（IDPT-ED）were designed,simulated,optimized and compared by simplifying raw materials and starting from the selection of extractants.The results show that although IDPT-ED process shows great energy-saving potential,its TAC is higher than CEDC process due to the need to add compressor;Compared with CEDC process,the thermal load of EDWC process is smaller,but it needs more high-grade heat sources,its TAC is also relatively high,while IR-EDWC process shows better effect,and its TAC and CO₂emissions are better.Compared with the CEDC process,the CO₂emission can be reduced by 41.9%and24.9%respectively.In order to ensure the accuracy of the data in this thesis,the simulation optimization of IR-EDWC process with the original C5 pretreatment product as the feed is further completed.The results show that compared with CEDC process,it can save TAC by30.78%and reduce CO₂emission by 44.32%.Considering that the raw materials of RDWC and IR-EDWC processes are complex and highly coupled,the research on their dynamic control is also the focus and difficulty.Therefore,in the fifth chapter,the position of the temperature sensitive plate and the pairing relationship between the temperature sensitive plate and the controlled variables are determined through the improved relative gain matrix and non square relative gain matrix method.Based on this,the control scheme design,simulation calculation and disturbance analysis of RDWC and IR-EDWC processes are completed.From the dynamic response results of the disturbance,it can be seen that the control scheme designed in this chapter can better deal with the flow and composition disturbances,Its instantaneous deviation and residual error are very small,and its transition time is also satisfactory for the highly thermal coupling process control process under such complex feeding conditions.