Comparison of Mass Transfer Characteristics between Countercurrent-Flow and Crosscurrent-Flow Rotating Packed Bed

The rotating packed bed (RPB), mainly including the countercurrent-flow RPB (Counter-RPB) and the crosscurrent-flow RPB (Cross-RPB) that are classified from the perspective of gas-liquid contact style, is a novel process intensification device. A significant measurement standard for evaluating the performance of RPB is the mass transfer effect In order to compare the mass transfer characteristics of Counter-RPB and Cross-RPB with the same size, the liquid volumetric mass transfer coefficient (k(L)a(e)) and effective interfacial area (a(e)) were measured under identical operating conditions. Meanwhile, the comparison of comprehensive mass transfer performance was conducted using the ratio of Delta P (pressure drop) to k(L)a(e) as the standard. Experimental results indicated that k(L)a(e) and a(e) increased with the increase in liquid spray density q, gas velocity u, and high gravity factor beta. Furthermore, compared with the Cross-RPB, the Counter-RPB has higher liquid volumetric mass transfer coefficient and slightly larger effective interfacial area. The experimental results of comprehensive mass transfer performance showed that the Counter-RPB had higher Delta P/k(L)a(e), than the Cross-RPB with changes in liquid spray density and high gravity factor, and there exists a turning point at 0.71 m/s accompanied by a variation with gas velocity. Moreover, the relative error of experimental value to calculated value, which was computed by the correlative expressions of k(L)a(e), was less than 5 %. In conclusion, the mass transfer characteristics of RPB are deeply impacted by the manner in which the flows are established and the Cross-RPB would have a great potential for industrial scale-up applications.