【摘要】：聚乙烯醇是一種重要的高分子化工原料,被廣泛應(yīng)用于多個(gè)領(lǐng)域。聚乙烯醇聚合工序中大量的醋酸乙烯單體未參與聚合。醇解過程中,聚醋酸乙烯醇解產(chǎn)生大量醇解廢液,其中主要組成為醋酸甲酯和甲醇。這些都是重要的化工原料,一般通過精餾工藝分離回收再利用。因此,聚乙烯醇聚合工段和回收工段精餾工藝進(jìn)行深入研究有助于優(yōu)化工藝過程,提高經(jīng)濟(jì)效益。Aspen Plus流程模擬軟件是輔助工藝研究的重要工具。本文在熟悉國內(nèi)某公司10萬噸/年聚乙烯醇聚合工段和回收工段精餾工藝的基礎(chǔ)上,利用Aspen Plus對其進(jìn)行流程模擬。根據(jù)物系特點(diǎn)分析,聚乙烯醇聚合工段精餾工藝中聚合一塔、聚合二塔和聚合三塔采用NRTL模型,聚合四塔和聚合五塔采用WILSON模型。聚乙烯醇回收工段精餾工藝中回收一塔、回收二塔、回收三塔、回收四塔、回收五塔和回收七塔采用NRTL模型,回收六塔采用NRTL-HOC模型。根據(jù)所選的熱力學(xué)模型,對聚乙烯醇聚合工段和回收工段精餾工藝進(jìn)行單塔以及全流程的模擬計(jì)算,對比實(shí)際值,驗(yàn)證模型的可靠性。在聚乙烯醇聚合工段和回收工段精餾工藝流程模擬的基礎(chǔ)上,利用Aspen Plus靈敏度分析工具分析理論板數(shù)、回流比、塔頂餾出率和進(jìn)料位置等工藝參數(shù)對各塔分離指標(biāo)的影響,獲得較優(yōu)的工藝參數(shù)。通過優(yōu)化后工藝參數(shù),調(diào)整流程模擬,得到回收的醋酸乙烯產(chǎn)品質(zhì)量分?jǐn)?shù)達(dá)到99.86%,整個(gè)聚合工段精餾裝置再沸器熱負(fù)荷降低8.02%,工藝用水減少12.1%。回收的乙醛質(zhì)量分?jǐn)?shù)為98.34%,回收的甲醇質(zhì)量分?jǐn)?shù)為99.94%,回收二塔采出的甲醇蒸氣質(zhì)量分?jǐn)?shù)為99.92%,用于分解的醋酸甲酯質(zhì)量分?jǐn)?shù)為92.58%,用于回收醋酸的水溶液中醋酸質(zhì)量分?jǐn)?shù)為56.13%,回收工段精餾裝置再沸器熱負(fù)荷降低4.8%。結(jié)果表明,通過優(yōu)化工藝參數(shù),達(dá)到了節(jié)能降耗的目的。
[Abstract]:Polyvinyl alcohol (PVA) is an important polymeric chemical raw material, which is widely used in many fields. A large number of vinyl acetate monomers were not involved in the polymerization of polyvinyl alcohol. In the process of alcoholysis, polyvinyl acetate alcoholysis produces a large amount of alcoholysis waste liquid, mainly composed of methyl acetate and methanol. These are important chemical raw materials, which are generally separated and reused by distillation process. Therefore, the further study on the distillation process of polyvinyl alcohol polymerization section and recovery section is helpful to optimize the process, and the. Aspen Plus process simulation software is an important tool to assist the process research. On the basis of familiar with the distillation process of 100000 t / a polyvinyl alcohol polymerization section and recovery section in a domestic company, the Aspen Plus was used to simulate the process. According to the characteristics of the polymerization system, the polymerization of polyvinyl alcohol in the distillation process was carried out in the first column, the second column and the third tower were modeled by NRTL, and the four towers and the five towers were modeled by WILSON. In the distillation process of polyvinyl alcohol recovery section, one tower is recovered, two towers are recovered, three towers are recovered, four towers are recovered, five towers and seven towers are recovered by NRTL model, and the NRTL-HOC model is used for six towers. According to the selected thermodynamic model, the distillation process of polyvinyl alcohol polymerization section and recovery section were simulated and calculated in a single column and the whole process, and the reliability of the model was verified by comparing the actual values. Based on the simulation of the distillation process of polyvinyl alcohol polymerization section and recovery section, the effects of theoretical plate number, reflux ratio, tower top distillation rate and feed position on the separation index of each column were analyzed by Aspen Plus sensitivity analysis tool. The optimum process parameters were obtained. By optimizing the process parameters and adjusting the process simulation, the recovered vinyl acetate product mass fraction reached 99.86, the heat load of the reboiler of the whole polymerization section distillation unit was reduced by 8.02 and the process water consumption was decreased by 12.1. The recovered mass fraction of acetaldehyde was 98.34, the recovered mass fraction of methanol was 99.94, the mass fraction of methanol vapor recovered from the second tower was 99.92, and the mass fraction of methyl acetate for decomposition was 92.58. The mass fraction of acetic acid in the aqueous solution for recovery of acetic acid is 56.13 and the heat load of the reboiler of the recovery distillation unit is reduced by 4.8%. The results show that the energy saving and consumption reduction can be achieved by optimizing the process parameters.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ316

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