Study On Separation Process Design Of Poly-component

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.