Debottlenecking Of Acetonitrile Extractive Distillation Butadiene Plant

Being an important and basic organic material and synthetic rubber monomer in the petrochemical field, butadiene is one of the most important components in the C₄ mixture, the status of which is just inferior to ethylene and propylene in the petrochemical raw materials of olefin. Substitution reaction, addition reaction, cyclization reaction and polymerization reaction can be conducted because of the conjugated double bond involved in its molecule, and therefore it is widely used in synthetic rubber and organic synthesis.Recently, comprehensive utilization of the C₄ mixture is a pressing problem along with the continuous revamping of ethylene plants, especially for existing butadiene plants. So they have been revamped in many enterprises in order to alleviate the pressure of improving the capability though substituting the new type of tray or downcomer. Double pressures of vapor and liquid phases will be loaded onto the trays after revamping because of the requirement about the high ratio of ACN/C₄ in extractive distillation process, and thus some potential problems such as entrainment will be exposed at a lower load. If the trays are designed without enough allowance, these questions will influence the operating stability; even cause the emergence of the flood.In September 2001, the plant of acetonitrile extractive distillation for butadiene in BYPC (Bingjing Yanshan Petrochemical Company) was finished revamping. After that, such problens as instability and flooding emerged due to the bottlenecks of the flaws in design itself and the usage of old equipment. The result of gamma-beam examination discovered that the entrainment is severe inside the column, and the load on the center downcomer was extremely serious. The feasibility of improving hydraulics is studied in this topic and hereby the technological revamping and process optimization was conducted.Upon the technological revamping and process optimization, de-bottlenecking the plant and the stability and capability were increased greatly. The capability increased from 54kta in 2002 to 67kta in 2004.