Cross-flow absorber operation

In Fig. 15-9 two potentiostatically controlled protection rectifiers and an additional diode are included to drain peak currents. At pipeline crossings with an external rail network (e.g., in regions outside the urban area), the forced stray current drainage should be installed as close as possible to the rails that display negative potentials for the longest operation time. The currents absorbed from the positive rails continue to flow also in the region outside the rail crossings. Here the use of potentiostatically controlled rectifiers is recommended these should be connected not only to the rails but also to impressed current anodes. 

A tower packed with metal Montz B1-300 structured packing is to be designed to absorb S02 from air by scrubbing with water. The entering gas, at an S02-free flow rate of 37.44 mol/m2-s of bed cross-sectional area, contains 20 mol% of S02. Pure water enters at a flow rate of 1976 mol/m2-s of bed cross-sectional area. The exiting gas is to contain only 0.5 mol% S02. Assume that neither air nor water will transfer between the phases and that the tower operates isothermally at 2 atm and 303 K. Equilibrium data for solubility of S02 in water at 303 K and 1 atm have been fitted by least squares to the equation (Seader and Henley, 1998) ... 

---