Process Design And Simulation Of 1,3-Butadiene Production From Ethanol

1,3-butadiene is an important organic chemical material and plays an important role in synthetic rubber industry.There are mainly three methods for the production of butadiene: ethanol method,dehydrogenation of butene or butane,separation of the by-product C4 from ethylene cracking by extractive distillation.The latter two methods belong to petroleum route.Ethanol method can use bioethanol as raw material,so it owns great advantage and potential in the long run.In this work,a new process for butadiene production from ethanol with annual output of 150000 tons was established.The process mainly contains four sections: the reaction section,crude separation of butadiene,refine of crude butadiene,ethanol recovery.Compound ethanol absorption method was proposed for the crude separation of butadiene,which performed very well and avoided the discharge of by-product acetaldehyde and ethyl ether from overhead of the absorption tower.Through simulation and calculation,the main process parameters of each section were optimized.And under the optimum conditions,the final purity of butadiene can reach 99.83wt%,confoming to the quality requirements of polymer grade.Three control schemes were designed and tested for the absorption-desorption system,key part of the butadiene process,by dynamic simulation.Based on CS1,CS2 changed the manipulated variable for desorber bottom level from withdrawal of bottom kettle to feed rate of fresh sorbent,which greatly reduced the fluctuation time when facing the sudden 10% increases of feed gas.In CS3,on the basis of CS2,feedforward control was added for the feed rate of recycle sorbent and the reboiler duty of desorber,and the maximal fluctuating amplitude of butadiene content in off-gas was significantly reduced.For the sudden 10% decreases of feed gas and the sudden 10% increase/decrease of butadiene mole fraction in the feed gas,each control scheme can perform well.In terms of the above four kinds of interferences,CS3 was the optimal in the three control schemes.The process design and steady state simulation of butadiene production from ethanol,as well as the control structure design and dynamic simulation for the absorption-desorption system,can give some guidence for industrial production of butadiene from ethanol.