Equations for Various Types of Dryers

In Fig. 9.10-1 the gas enters at Ti and H, and leaves at T2 and H. Hence, the temperature T and humidity H both vary through the bed. Making a heat balance over 

For the constant-rate period of drying by air flowing parallel to a surface, Eq. (9.6-11) was derived. 

Substituting Eq. (9.10-6) into (9.6-11) and setting X = Xc for drying toXc, we obtain the equation for through circulation drying in the constant-rate period. 

In a similar manner, Eq. (9.7-8) for the falling-rate period, which assumes that R is proportional to X, becomes, for through circulation drying. 

---

Figure 9.10-2. Heat and material balances in a tray dryer. Sec. 9.10 Equations for Various Types of Dryers...

The objective of this chapter is to briefly present the current technology for dryer emission control systems via flowcharts, tables, design equations, and practical description of various dryer emissions and control systems. Recent developments, trends, and regulations are also discussed. No attempt is made to give full design details or to include all dryer emission control equipment. Discussion will therefore be limited to some of the better-known, well-proven, and widely used devices. The reader is referred to the literature cited for more details and additional information on specific types of emission control systems mentioned in this chapter. 

---