Concentration profile limestone particle

Single Pellet One Reaction. The sulfation reaction which is considered here for calcium carbonate is given by Eq. 3, and the temperature and concentration profiles of a typical growing limestone particle are shown in Figure 2. The rate of disappearance of sulfur dioxide is assumed to be the first order and is given by... 

Figure 2. Gas-solid reaction of a growing limestone particle at height H in the fluidized bed concentration and temperature profiles...

The refined source profiles that best reproduced the coarse fraction are listed in table 7. The calculated profiles of the two crustal components follow those of Mason ( ), though the calcium concentration of 20 in the limestone factor is less than the reported value. The paint pigment profile strongly resembles that calculated for the fine-fraction data. The only major difference is that unlike the fine fraction, the coarse-fraction profile does not associate barium with the paint-pigment factor. The calculated sulfur concentration in the coarse-fraction sulfate factor is much less than that in the fine-fraction and there are sizable concentrations of elements such as aluminum, iron, and lead not found in the fine-fraction profile. The origin of this factor is not clear although as described earlier a possible explanation is that a small part of the sulfate particles in the fine fraction ended up in the coarse samples. 

Interestingly, Rajamani and Milin found no need to iterate for feed concentrations up to 20% by weight where clean water velocity profiles were used and the separation results compared well with experiments (limestone in water, in a 75 mm hydrocyclone). This is due to the fast dilution process taking place in the flow as pointed out in section 1.4. Only for concentrations above 20% by weight the authors needed to iterate the computations the first iteration of particle trajectories is done with the values of water viscosity and density, from which particle concentrations (and slurry viscosities and densities) are computed at each point. For this the authors use computed particle trajectories and assume that the concentration is proportional to particle residence time in each computational cell. 

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