【作者】 温雅；

【导师】 胡仰栋；

【作者基本信息】 中国海洋大学 ， 化学工程， 2007， 硕士

【摘要】 分离过程的设计通常以系统的总费用最小为目标,涉及选择适宜的分离方法,确定最优的分离序列,实现系统热集成等环节,是化工过程系统工程研究的重要问题之一。对多组分分离过程,相平衡模型及计算方法是过程设计最关键也是最复杂的环节,然而目前仍未有更简单有效的针对多组分相平衡问题的计算方法。本文在分析多组分分离过程本身特性的基础上,提出了一种基于拟二元法的相平衡计算方法,并将该法用于分离过程设计问题的研究。1、用拟二元相平衡模型表达多组分精馏与恒沸精馏的相平衡关系,并可求取得到拟二元体系的平衡数据和平衡相图,且可直接用于多组分精馏过程的图解设计计算。提出基于迭代的拟二元逐级计算的多组分精馏塔的设计法。首先采用基于优化的逐级计算法计算每块塔板上各物质的组成,然后进行拟二元精馏过程的设计。实例研究表明:这一方法也可以容易的得到多组分精馏的最小回流比和最少理论板数;而且也适用于理想、非理想体系,对恒沸精馏该方法也能得到比较好的结果。2、提出一种多组分精馏塔的简捷设计法。首先应用Aspen plus软件模拟计算每块塔板上各物质的组成,然后通过VB语言编程进行拟二元精馏过程的设计,并通过软件集成使整个设计过程可以自动运行。实例研究表明,这一方法很容易得到多组分精馏的最小回流比和最少理论板数;既可以用于理想的精馏体系又可以用于非理想的精馏体系;对于有夹带剂加入的恒沸精馏过程,这一方法仍然适用。3、针对改良西门子法多晶硅生产中尾气分离工艺操作条件苛刻的缺点,对尾气分离工艺进行改进。首先应用Aspen plus软件,将精馏、吸收、吸附等不同分离方法进行组合,确定分离尾气混合物的分离序列,并构建了四个可行的工艺流程。模拟结果表明:四个流程都可在比较温和的操作条件下达到较好的分离效果;其次用温焓图进一步分析各流程的能量利用情况,结果发现:四个流程进行热集成的意义不大,但分离所需的冷凝温度为250K,易于实现;最后比较四个流程的设备以及流程中吸收剂的加入量、主要设备的操作压力、接吸附的流股中H2的摩尔分率、QH,min和QC,min的大小,最终得到了分离尾气的最佳流程。该流程在第①步中用两个闪蒸罐完成分离,用作预分离的闪蒸罐操作压力为506.6kPa;第②步的吸收过程可将H2由0.89提高到0.981(摩尔分率),吸收剂用量为278kmol/h;第③步塔顶分凝器所需温度为253K,且可将HCl比较完全的分离到塔顶;第④步吸收剂用量为111kmol/h,HCl被提纯到0.99;第⑤步为简单的二元精馏,进料混合物中仅含有SiHCl3和SiCl4。更多还原

【Abstract】 The design of separation process generally makes the minimum total expense as object , involving selecting proper separation method,determining optimum separation sequence , realizing system heat integration etc, which is a important problem studied in chemical process systems engineering . In poly-component separation process, phase equilibrium model and calculation method are the most pivotal and complicated link, there is not yet a simplified calculation method which can be used to solve poly-component phase equilibrium problem simply and effectively at present. A new phase equilibrium calculation method based on quasi-binary method is put forward based on analysis of the self property of poly-component separation process, and this method is used in the study of separation process design problem.1、quasi-binary based phase equilibrium model can be used to express phase equilibrium relationship of poly-component distillation and azeotropic distillation. The equilibrium data and the equilibrium phase diagram of quasi-binary system can be attained and can be applied in graphical design of poly-component distillation process direct. The iteration based quasi-binary stage by stage calculation poly-component distillation column design method is put forward. This optimization based stage by stage computation method is used to calculate the component composition on every stage, and the design of quasi-binary distillation process is carried out. It is indicated from examples study that: the minimum reflux rate and smallest theory stages can be attained easily by this method; the method not only suits for ideal distillation system but also suits for non-ideal distillation system; and the better results can be attained when this method is used to in azeotropic distillation.2、A poly-component distillation column shortcut design method is put forward based on quasi-binary method: firstly Aspen plus software is used to simulate every component composition on every stage, and the design of quasi-binary distillation process is carried out through VB language programming and can be run automatically through software integration. It is indicated from examples study that: the minimum reflux rate and the smallest theory stages can be attained easily by this method; the method not only can be used in ideal distillation system but also can be used in non-ideal distillation system; and also can be used in constant boiling distillation process with entrainer added in.3、As to the shortcoming of rigorous operation condition of stove tail gas separation technology in the modified siemens polycrystalline silicon production , the tail gas separation technology is modified. Firstly Aspen plus software is used to combine different separation methods for example distillation、absorption、adsorption et al .The tail gas separation sequence is fixed on, and four feasible process flows are built, it is indicated by simulating results that: the four flows all can reach better separation effect under moderate operation conditions. Secondly temperature-enthalpy diagram is used to analyses energy utilization state of every flow, and it is discovered that there is little significance for heat matching of the four flows, but the condensing temperature requirement of the separation process is 250K, which is easy to be realized. Finally the optimal flow is attained for the separation of tail gas through comparing parameters of material adding quantity of four flow equipments and adding quantity of absorbent、major equipments operation pressures、the H2 mol rate in feed flow of adsorption column, the size of QH,min and QC,min. In the first step of this flow, two flash tanks is used to complete separation, the flash tank used for pre-separation is operated at pressure of 506.6kPa; in the second step, H2 mol rate can be raised from 0.89 to 0.981 in adsorption process , absorbent dosage is 278kmol/h; in the third step, the temperature requirement of fractional condenser on top of column is 253K, and HCl can be separated completely from the top of column; in the fourth step, absorbent dosage is 111kmol/h, HCl purity is purified to 0.99; the fifth step is about simple binary distillation, only SiHCl3 and SiCl4 is contained in feed mixture.更多还原