# Fig xA Schematic of fluidized bed Figure optionsDownload full size

Fig. 3. Schematic of fluidized bed.Figure optionsDownload full-size imageDownload as PowerPoint slide

3.2. Mass balance in the continuous phase

Eqs. (17) and (18) show the material balance in the continuous phase. Where r is a symbol of the reaction rate and is determined according to Eq. (1) which is a pseudo first-order chemical reaction. The rate of reaction depends on the SO2 concentration.equation(17)m?bcon. z-m?bcon. z+Δz-m?mcon.-m?r=macc.equation(18)AUmfCc z-AUmfCc z+Δz-NQ(Cc-Cd)-r=Vc∂Cc∂t

The unreacted core model justifies this S Tag dependency. According to this model, the reaction occurs on the outer layer of catalyst initially and then continues in the other inner layers. So, the whole catalyst will be deactivated, finally. Regeneration process should occur to keep the catalyst active. It is assumed that the catalyst dimensions remain unchanged during the reaction, so the rate of reaction is expressed as Eq. (19). The rate of solid–gas reaction is determined by two diffusion resistances which one is between the catalyst layers and the other is in chemical reaction. So, K is defined as Eq. (20). Where, Ks the constant rate of the first order reaction is expressed as Eq. (21).equation(19)r=kAcCcr=kAcCcequation(20)k=1rp(rp-rc)rcDeff.+rp2rc2ksequation(21)ks=ksoexp-EaRT