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Catalyst loading, W^rd

Figure 16.34 (a) Effect of catalyst loading in column base (Wcat,bot) on TACs and (b) tradeoff of separator cost (excluding catalyst cost), reactor cost, and bottoms catalyst cost.

Catalyst loading, W^rd

Figure 16.34 (a) Effect of catalyst loading in column base (Wcat,bot) on TACs and (b) tradeoff of separator cost (excluding catalyst cost), reactor cost, and bottoms catalyst cost.

The effects of side stream flowrate FSS on the side reactor configuration design are demonstrated in Figure 16.33a. The optimum side stream flowrate is 1500 kmol/h. A larger side stream flowrate requires a larger reactor volume and more catalyst to achieve the same conversion, which leads to an increase in the reactor cost, as shown in Figure 16.33b. Because more reaction in the side reactor reduces the loading of the column, the separator cost decreases.

Finally, we address the effects of catalyst loading in the column base (Wcat,bot) on the side reactor configuration design. Figure 16.34a shows that Wcat,bot = Wcat,RD is the optimal catalyst amount. As the bottoms catalyst increases, more reaction occurs in the column base. Therefore, the separator requires less vapor flowrate, and the volume of the side reactor is smaller. The tradeoff is revealed in Figure 16.34b. If there is no catalyst in the column base (Wcat,bot = 0, only a side reactor for the reaction), this configuration can still work. However, it requires a larger flowrate of the side stream and a considerable amount of catalyst to achieve the product specification.

Catalyst loading, M^rd

Catalyst loading, Wcat RD

Figure 16.35 (a) Relationships between design variables: catalyst loading versus optimized percentage of equilibrium conversion (%Xeq; to achieve minimum TACs) and (b) catalyst loading versus the optimized side stream flowrate (to achieve minimum TACs).

Catalyst loading, Wcat RD

Figure 16.35 (a) Relationships between design variables: catalyst loading versus optimized percentage of equilibrium conversion (%Xeq; to achieve minimum TACs) and (b) catalyst loading versus the optimized side stream flowrate (to achieve minimum TACs).

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