Study On Separation Technology Of Nbutanol-Isobutanol-Water System

Butanol,n-butanol and iso-butanol,are important organic chemical raw materials and high-energy alternative fuels,which are widely used.In recent years,the rapid increase in demand and the continuous increase in energy prices put forward higher requirements for butanol recovery and utilization,so it has considerable economic,energy and environmental protection value to recover butanol effectively from waste liquid for reuse.Although the recent increase in oil prices and CO₂ emissions has once again caused concern for the bio-butanol production technology,but the technology has low yield and high energy consumption,so butanol is still mainly relied on oil refining production.For butanol-water systems,it is present in a variety of chemical wastewater effluents.Not only cause serious harm to the environment,at the same time,due to the lack of effective process technology for the recovery of mixed butanol in China,but also cause waste loss of important organic chemical raw materials.In this paper,a chemical enterprise in Shandong province butanol production wastewater as the research object,using chemical simulation development platform aspen plus for its development process and simulation calculation,using aspen plus UNIQUAC model to predict its vapor-liquid and liquid-liquid equilibrium,the results show that the data in good agreement with the literature,proved that the model simulation calculation data is accurate and reliable.N-butanol-isobutanol--water system was separated and recovered at a mass flow rate of 100 t/h.Because the ternary system can form azeotrope,the separation of high purity can not be realized by ordinary distillation.In this paper,the conventional azeotropic distillation and extractive distillation?using 1,4-butanediol as extractant?were used to construct and simulate the mixed system,and the necessary tray number,feed position,reflux ratio and other important parameters were optimized.The purity of n-butanol,iso-butanol and water can reach99.99%?w%?respectively,and the purity of extractant in extractive distillation can reach more than 99.99%?w%?.Based on the high energy consumption of the traditional two separation methods,an energy-saving extractive distillation process is proposed in this paper.the vacuum operation of the extractive distillation column is carried out.part of the heat source of the reboiler in the column bottom comes from the high-temperature steam at the top of the solvent recovery column.Thus,the latent heat of the steam is fully utilized,and energy saving is realized.Aspen plus was used to optimize the process,and the important operating parameters such as plate number,feed position,reflux ratio and solvent ratio were obtained.The purity of n-butanol,iso-butanol and wat can reach99.99%?w%?respectively,and that purity of extractant can reach more than 99.99%?w%?.Finally,the economics of the three processes are calculated and compared.it is found that azeotropic distillation has obvious advantages over traditional extractive distillation in terms of energy consumption.the annual investment cost of traditional extractive distillation in steam is 5.64 million dollars more than that of azeotropic distillation.Traditional extractive distillation processes are also about$1.50 million higher in equipment investment.The total operation cost of the new process is saved by 5.38 million us dollars per year compared with the azeotropic distillation process,and the operation cost of the original process is saved by 50.90%per year;Compared with the traditional extractive distillation process,the operation cost of the original process is saved by 68.02%every year by saving$11.02 million.In tac,the new process saved$5.16 million,about47.77%,compared with azeotropic distillation.Compared with the traditional extractive distillation process,the new process can save us$10.95 million,about65.99%,and the benefit is remarkable.