Theory of Air-Water Interaction in Packed Towers

Variable Increased Factors Increased Factors Decreased 

Chamber inlet temperature Feed rate and thus product rate, particle size product moisture content, chamber wall build-up (a) bulk density (b) 

Chamber outlet temperature product thermal degradation feed rate and thus  

Feed concentration Atomizer speed Atomizer disc diameter product rate, bulk density [b], particle size (b)  

The key properties of mixtures of air and water vapor are described in Section 9.1. Here the interactions of air and water in packed towers under steady flow conditions will be analyzed. The primary objectives of such operations may be to humidify or dehumidify the ait as needed for particular drying processes or other processes, or to cool process water used for heat transfer elsewhere in the plant. Humidification-dehumidification usually is accomplished in spray towers, whereas cooling towers almost invariably are filled with seme type of packing of open structure to improve contacting but with minimum pressure drop of air. 

21) the heat capacity of water has been taken as unity. The approximations that are involved in making an enthalpy difference a driving force are discussed for example by Foust et al. (1980). Rearrangement and integration leads to the results 

TABLE 9.19. Product Numbers and Performance of a 30 X 29 in. Pilot Plant Spray Dryer 

Both forms of the integral are employed in the literature to define the number of transfer units. The relation between them is 

Integration of Eq. (9.21) provides the enthalpy balance around one end of the tower, 

---

THEORY OF AIR-WATER INTERACTION IN PACKED TOWERS 277 TABLE 9.18. Effects of Variables on Operation of Spray Dryers... 

---