| Epichlorohydrin(ECH),which is a large variety of propylene derivates,is a kind of important organic chemical raw materials,mainly used for the synthesis of epoxy resin,chlorohydrin rubber,nitroglycerine,etc.The epichlorohydrin industrial production methods have high temperature propylene chlorination process,allyl acetate method and the emerging glycerin method.Although glycerol method has many advantages,as oil prices fell sharply,propylene prices plunged,allyl acetate method which characters of low raw material consumption,less wastewater discharge and high product quality compared with the high temperature chlorination process still has living space.Bo Tian chemical plant has two sets of phase?and ? ECH production equipment,in which Japan showa denko allyl acetate method patent technology is used,and has production capacity of 60,000 tons/year.The process allyl acetate production process includes two independent production units,AAL production unit and ECH production unit.In AAL unit,with noble metals as catalyst,the catalytic oxidation reaction of propylene,oxygen and acetic acid occurs in oxidation reactor.The reaction product is allyl acetate.Then,allyl acetate hydrolyzes via hydrolysis reactor to get allyl alcohol(AAL).The obtained allyl alcohol is refined to get 70% allyl alcohol aqueous solution.In EC H unit,the 70% allyl alcohol aqueous solution from AAL unit attends the chlorination reaction in low temperature.The reaction product is 2,3-dichloro propyl alcohol(DC H).The obtained DCH is distilled before saponification synthesis of epichlorohydrin(EC H).The crude ECH is refined through distillation to get the final product ECH.The chemical process simulation software Aspen P lus is used to simulate and analys the problems existing in the operation of epichlorohydrin device of allyl acetate method,the modification schemes and the optimization measures are put forward.Choosing the appropriate property methods,aiming at the problem of high concentrations of allyl alcohol at the bottom of AAL tower,the AAL tower is simulated and the sensitivity analysis is done successively using equilibrium calculation type and rate-based calculation type.The modification scheme is determined by increasing the packing height of stripping section.And the process optimization of the reflux ratio is done.In view of poor HCL desorption effect and frequent flooding problems in hydrochloric acid stripping tower of phase II,rating simulation and sensitivity analysis are carried out to find the reasons for abnormal tower operation.And then the targeted tower internal parts were modified.For large resources waste problem due to discharge of organic waste liquid containing trichlorpropan(TCP)in ECH unit,simulated calculation of distillation process of separation and purification of trichlorpropan is done.After modification and process optimization scheme is applied to the AAL tower in the phase II.AAL content in the bottom product of the AAL tower is greatly reduced from more than 2000 ppm to around 40 ppm.The result is satisfied.Through the modification of feed liquid distributor,liquid redistributor,vapor phase feeding tube,packing support plate in phase II hydrochloric acid stripping to wer,HC L stripping effect is close to the normal reference value and frequent flooding phenomenon disappears.According to the result of Aspen Plus simulation,products containing more than 90% TCP can be obtained simply by adding a packing column.Through adjusting the design and operation parameters of the tower and the epichlorohydrin refining process,TCP product solutions with concentration higher than 95% or 99% product solutions can also be got to meet the different needs of the market. |
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