Micromixing Efficiency Of A Rotating Packed Bed With Foam Packings

Micromixing efficiency of a reactor has direct influence on the chemical reaction process, especially on the fast complex reactions. The selectivity and conversion of chemical reactions can be changed by the micromixing efficiency, which resulted in the change of the quality of final products. Thus, it is necessary to extensively investigate the micromixing efficiency of reactor.A rotating packed bed (RPB) can greatly intensify the process of mixing and transfer, and it has been widely used in many fields such as chemical engineering, environmental protection, and preparation of nanomaterials. As the core part, the packing loaded in the rotor of a RPB is vital to the process of mixing. In this paper, we studied micromixing efficiency in a RPB with different ceramic foam packings and nickel foam packings by using the iodate-iodide test system, and the influence of microstructure on packing’s surface and hydrophobicity of packing on micromixing efficiency were discucced. On the base of experimental study, micromixing characteristic time of RPB with different packings was calculated by the incorporation model. Some findings are listed below:(1) Micromixing efficiency of the RPB with ceramic foam packing increased with the increase of rotational speed and solution flowrate, and it decreased with the increase of the volume flow ratio and the concentration of hydrogen ion. Compared with the RPB with stainless mesh packing, the micromixing efficiency in the RPB with ceramic foam packing was greatly improved. It was noted that the ceramic foam packing with smaller aperture has better micromixing efficiency. And microstructure (aperture<500nm) on packing’s surface obtained by chemical etching can further improve the micromixing efficiency in the RPB.(2) Within the low rotational speed range, the high micromixing efficiency of the RPB with the ceramic foam packing with or without modificaiton can be obtained.(3) The micromixing efficiency of the RPB with either nickel foam packing of larger aperture (5ppi) or stainless steel mesh had the same trend with the change of rotational speed, the former was better than the later. The nickel foam packing of smaller aperture (50ppi) can not only improve the micromixing efficiency, but also keep it stable in the occasion of lower rotational speed.(4) After the modification of the nickel foam packing, the contact angle of the packing was increased by30°, which decreased the effect of feed flowrate and led to the segregation index was a almost the linear function of the rotational speed and flowrate.The enhancement of the micromixing efficiency was found.(5) The micromixing characteristic time of the RPB with foam packings was smaller than that of the RPB with stainless steel packing. The micromixing characteristic time of the RPB with modified foam packing was smaller than that without modified ones. And the RPB with modified nickel foam packing (50ppi) had the smallest micromixing characteristic time(3.28-4.63ms) in present study.