A STUDY ON MULTICOMPONENT, BULK GAS MIXTURE SEPARATION BY PRESSURE SWING ADSORPTION AND ON BREAKTHROUGH CURVE.

摘要

In this work, the multicomponent, bulk gas mixture separation by PSA processes were studied experimentally and theoretically. The gas mixtures up to quinary system, including H(,2), CO, CH(,4), CO(,2) and H(,2)S, are typical composition in coal gasification products. A high purity H(,2) product, a high purity CO (from H(,2)/CO binary system) or CH(,4) (from H(,2)/CH(,4)/H(,2)S ternary system) product, a clean fuel gas product (from quinary system) and an acid gas product were obtained by single column PSA processes. The effects of operating conditions, such as feed rate, feed pressure, purge/feed ratio and cycle time etc., on PSA separation were studied. It was found that the bed utilization on adsorption step and the cocurrent depressurization step were the major factors on the purities of strongly adsorbed components.; A mathematical model was proposed to study the performance of multicomponent, bulk PSA processes in which both mass and heat balance were considered. An equilibrium model, a linear-driving-force model and a pore diffusion model for mass transfer were applied and compared in the model simulation of PSA processes. The predicted PSA separations were in good agreement with the experimental data. The model was able to predict PSA performance at various operating conditions. The numerical method used in this work was stable and convergent.; The high and low temperature zones which would ruin the gas separation were observed in commercial size PSA apparatus, it also was predicted by the adiabatic PSA model. Two methods, heat exchanger PSA and inert additives, were suggested to improve the temperature distribution along the column. The model simulations proved that these two methods could improve the PSA separation significantly.; An analytical solution for breakthrough curve has been derived, in which external fluid film-macropore-micropore mass transfer resistances have to be considered. The solution was in good agreement with numerical solution and experimental data when one or two mass transfer resistances were important. The relative importance of each mass transfer resistance and equilibrium constant was studied by the solution.