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Study On Azeotropic Distillation Of Solvent Dehydration In Production Of Terephthalic Acid

Posted on:2007-11-04Degree:MasterType:Thesis
Country:ChinaCandidate:J ZhouFull Text:PDF
GTID:2121360212468059Subject:Chemical Engineering
Abstract/Summary:PDF Full Text Request
Aimed at the dehydration inefficiency and high energy expenditure in the production of purified terephthalic acid in ordinary distillation process, correlative technologies at home and abroad were summarized in this paper, and then a new technology with lower energy expenditure and high recovery of acetate acid was developed. N-propyl acetate was selected as entrainer. Vapor-liquid phase equilibrium data for acetate acid + n-propyl acetate and water + acetate acid + n-propyl acetate was measured. The binary UNIQUAC parameters for acetate acid + n-propyl acetate were correlated. Based on the obtained UNIQUAC model parameters, combined with the model parameters in Aspen database, the solvent dehydration and recovery of p-xylene and methyl acetate processes were simulated by the Aspen Plus software. The influences of reflux ratio, numbers of theoretical plates, feed position, feed temperature, and feed concentration on the total technology had been studied on and preferred operation conditions were respectively obtained. According to the results of simulation, preliminary industry enlargement design calculation of the total technology was performed. Economic evaluation on the equipment cost, working expense and profit was concluded.The study results were as follows: (1) The azeotropic distillation process of solvent dehydration in the production of purified terephthalic acid had been preliminarily designed (had been applied patent in China, Publish NO. CN1696098). The technology was propitious to existing technology reconstruct for some corporation. (2)Vapor-liquid phase equilibrium data for acetate acid + n-propyl acetate and water + acetate acid + n-propyl acetate were measured by the modified Rose still. The thermodynamic consistency of the binary experimental data was carried out by the area test. The binary data for acetate acid + n-propyl acetate was correlated to obtain UNIQUAC parameters, which had been used to predict the ternary VLE data. The predict data were consistent with the experimental ones, which provided the basic data for the later azeotropic distillation simulation. (3) The solvent dehydration process for purified terephthalic acid yearly output 350,000 tones was simulated. The separation effect of solvent dehydration towers in this azeotropic distillation technology was so good that the acetic acid concentration of bottom tower was not less than 95%(wt.) and that of top tower was not more than 0.01%. The recovery of acetic acid was higher than 95%. The separation effect was much better than the ordinary distillation process. The recovered p-xylene concentration was higher than 99%, while the recovered methyl acetate concentration was not less than 96%. The drawback of...
Keywords/Search Tags:Purified terephthalic acid, Solvent dehydration, Vapor-liquid phase equilibrium, Azeotropic distillation, Simulation calculation, Scale-up and design
PDF Full Text Request
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