Activated carbon pressure drop through beds

Redesign the VOCs adsorber of Example 9.15 for a breakthrough time of 4.0 h. The pressure drop through the bed [calculated using the Ergun equation, (2-91)] should not exceed 1.0 kPa. Calculate the new dimensions of the bed and the total amount of activated carbon required. 

Small particle size activated carbon will produce a high pressure drop through the activated-carbon bed. Figure 22.1.12 compares the pressure drop of cylindrically-shaped activated carbon pellets with activated-carbon granulates. The activated carbon particle diameter must not be excessively large, because the long diffusion distances would delay adsorption and desorption. Commercially, cylindrical pellets with a particle diameter of 3 to 4 mm have been most efficient. 

Figure 12-41. Pressure drop through diy-packed activated-carbon beds for air flowing downward at 1 atm pressure and 70°F. Union Carbide Corp.

---