Dynamic Simulation Of Cryogenic Distillation Column With Hydrogen System

Researches into the nuclear fusion reactions has created a need for handling the deuterium tritium fuel employed, and cryogenic fractional distillation was selected as one of the best process for making the required separations due to relatively large separation factors, low power consumption, high throughputs, relatively short start-up times, and flexibility of design. However, only limited data have been available for hydrogen isotope system, so there is not a rigorous thermodynamics model which can accurately predict thermodynamic properties and phase equilibrium of hydrogen fluid by now. In this thesis a rigorous thermodynamics model which can accurately predicate thermodynamic properties and phase equilibrium of hydrogen fluid is established through the method based on equation of state. Using this thermodynamics model we have studied steady state as well as dynamic behavior by founding a fundamentally sound model that is capable of accurately describing the separation process.1. The BWR equation of state modified by Soave in 1999 is applied to the saturated hydrogen solutions. The parameters needed in the equation of state have been modified and optimized through fitting experiment date. p-T-V condition of the saturated hydrogen can be accurately predicted as well as thermodynamic properties and phase equilibrium of hydrogen fluid through this equation. A rigorous thermodynamic model which can be used in simulation of hydrogen isotope-separation by cryogenic distillation is then obtained.2. The rigorous thermodynamic model has been applied to study the characteristics of cryogenic distillation column having feedback stream with hydrogen isotope system in steady state. A side stream is recycled to the external feed stream of the column through an equilibrator as an internal feed stream. The simulation results indicate effects on the characteristics of cryogenic distillation column.Consideration is given to the behavior and characteristics of the set of ordinary differential equations. The numerical integration algorithm which can provide better stability, accuracy and efficiency in computing time has been investigated to solve complex cryogenic distillation dynamic3. problems. By dealing with the logarithmically transformed variables, the equation systems resulting from a dynamic simulation model of distillation processes become more well conditioned, and can be solved using a general integration method.4. The approach coded in MATLAB for dynamic simulation of a distillation column as well as the dynamic model window is described in the thesis. 5. The study of different processes and operations in dynamic behavior of a column has been done in detail using a rigorous thermodynamic model. The dynamic behavior of distillation column during start-up operations have been studied and analyzed. Similarly, the dynamic characteristics of a column having feedback stream with hydrogen system have been studied as well.6. A new kind of operation policy-Quasi-batch distillation is proposed for specific conditions in hydrogen cryogenic distillation. The dynamic behavior of a column in quasi-batch distillation is analyzed in some cases.