| Summary: | 碩士 === 長庚大學 === 化工與材料工程學系 === 104 === The numerical analysis method and Fortran software is used to simulate pressure swing adsorption of four step. With numerical simulation method we can figure out how the consequence change when the parameter change rapidly and find the most adapted condition of operation.
The assumptions of the mathematical model are: the mixture gas follow ideal gas law, neglecting pressure and velocity gradient on the axial direction, extended Langmuir isotherm formula is used, and use linear driving force model formula to describe the rate of mass transfer correlation between gas phase and solid phase. With the assumptions pre-condition we can get the mathematical model including mass balance equation in adsorption bed, mass balance equation in adsorbent, and energy balance equation. With Orthogonal collocation method, we can let the partial differential equation turn to normal differential equation and use the parameter and operational condition of the reference(S-J.Doong and R.T.Yang[1]) to substitute into the normal differential equation .Finally we use Fortran program to solve the equation and we can realize how to the mole fraction in bed ,the mole fraction in adsorbent and the temperature change from the change of time.
The results indicated that the time of feed step from 160s to 200s evaluate the productivity of hydrogen obtained at 550(mol/hr-kg) and the purity of hydrogen is no change , the purity of methane obtained at 26% and the productivity of methane obtained at 270(mol/hr-kg), the purity of carbon dioxide obtained at 40.5% and the productivity of carbon dioxide is not change.The increasing velocity ratio of purge step from 10.6 to 21.2 evaluate the purity of hydrogen is no change, and productivity of hydrogen is no change, the purity of methane obtained at 20%, and the productivity of methane obtained at 210(mol/hr-kg), the purity of carbon dioxide obtained at 31% and the productivity of carbon dioxide is not change. The increasing column length has no effect on purity,and the productivity of hydrogen obtained at 340(mol/hr-kg), the productivity of methane obtained at 190(mol/hr-kg) and the productivity of carbon dioxide is not change.
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