ABSTRACT

Packed towers, tray towers, and even spray towers can be used for energy recovery through the direct contact of a heat-absorbing liquid (usually water) with a hot gas stream. These devices may also simultaneously remove soluble gaseous pollutants. In these systems the rate of heat transfer is controlled by the difference in temperature between the hot gas and absorbing liquid. The amount of heat absorbed is controlled by the mass of liquid that passes through the device. Devices that are strictly counterflow, such as a packed or tray tower, exhibit higher heat transfer efficiency than devices such as a spray tower that may entrain liquid upward and therefore reduce the differential in temperature required for optimum heat transfer. With proper design, however, spray towers can be effectively used for heat recovery.