Cross-Flow versus Counterflow Air-Stripping Towers

Toluene removal from nonionic surfactant coacervate phase solutions by vacuum stripping

“…Many models have been proposed and developed for VOC mass transfer determination in countercurrent air [12][13][14][19][20][21][39][40][41] or vacuum stripping using a packed column [22,23,[25][26][27]. For example, Onda's correlations have been used for determining the mass transfer coefficient of VOC removal from water [20,39,40]. The surfactant air stripping model (SASM) was designed for examining the VOC mass transfer in surfactant recovery [13,14].…”

Air Stripping

“…The processes have been extensively applied for ammonia stripping, groundwater remediation, and industrial wastewater (ammonia and VOCs) stripping (21)(22)(23)(24)38). Crosscurrent stripping was found to be an advantage over the conventional countercurrent stripping because the mass-transfer coefficient in crosscurrent operation is insensitive to the gas flow rate, thereby allowing a high air-to-water ratio, G′/ ′ L / / ′, without chances of flooding (21).…”

“…Crosscurrent stripping was found to be an advantage over the conventional countercurrent stripping because the mass-transfer coefficient in crosscurrent operation is insensitive to the gas flow rate, thereby allowing a high air-to-water ratio, G′/ ′ L / / ′, without chances of flooding (21). Crosscurrent stripping also offers a significant economic advantage over countercurrent stripping due to the savings in energy costs, when the target contaminants are considerably less volatile (23). However, the drawback of applying a high air-to-water ratio in crosscurrent stripping is the increased cost of off-gas treatment.…”

“…With progressive development of the computer technology, substantial advancement has been made in the area of developing models to simplify the air-stripping tower design procedure so that the tower configuration associated with tower performance can be optimized and the overall cost (sum of capital and operating costs) associated with installation and operation can be minimized (22,23,(25)(26)(27)(28)(29). The relationships of optimum design parameters to Henry's law constants and the sensitivity of tower overall cost to specific design parameters can be well demonstrated by computer simulation (23).…”

“…The relationships of optimum design parameters to Henry's law constants and the sensitivity of tower overall cost to specific design parameters can be well demonstrated by computer simulation (23). By computer iteration, these programs provide a quick prediction of the tower performance with limited inputs of design parameters.…”