Study of heat and mass transfer in PSA carbon dioxide removel from flue gas

A two dimension mathematical model has been developed to simulate the coupled heat and mass transfer in a porous medium undergoing a bulk strong adsorption according to the volume averaging method. The traditional two phase equation model has been employed, the temperature field of bulk flow and the temperature distribution of the solid matrix is solved. The fluid flow is modeled by the Darcy-Forchheimer-Brinkman equation. The temperature-dependent Langmuir isotherm has been used to describe the equilibrium characteristic of CO2 and N-2 binary mix gas on the zeolite 13X. The mass transfer is described by linear drive force model(LDF), and the LDF coefficient is approximated as particle external mass transfer coefficient. The heat generated by adsorption is introduced to the solid matrix. The coupling of these two equations is given by the item of the interfacial heat transfer coefficient. This model is solved numerically by the alternate dimension implicit method, and the numerical results are validated by comparing with the experimental data in literature. An excellent agreement can be seen between the measurements and calculations. This ensure the model and the assumptions are rational, and the process of calculation is accurate. The adsorption features of the packed bed of pellets are analyzed under different conditions by varying the key parameters. The calculated results showed that, increase the bulk flow velocity makes the cycle time decrease, increase the capacity of per volume adsorbent,but the worsen of heat transfer performance and consume more energy. The d(p) increase lead the worse of heat and mass transfer performance slightly, but the flow resistance decrease significantly. Increase the length worse the heat and mass transfer performance, and the pressure difference increase, the throughput of per volume decrease. In a word, increasing the flow rate and d(p), decreasing the length of adsorber will be favarable for the adsorbption Of CO2 on the zeolite 13X. This study will be useful for the design of reactor and choosing the most reasonable operation conditions.