Feed-split heat integrated column

Figure 6.24 Heat-integrated columns, (a i Feed split binary) b) light-split reverse [binary) (e) prefractionator reverse (ternary).

Remark 2 The separators are sharp and simple distillation columns (i.e., sharp splits of light and heavy key components without distribution of component in both the distillate and bottoms one feed and two products). The operating conditions of the distillation columns (i.e., pressure, temperature, reflux ratio) are fixed at nominal values. Hence, heat integration options are not considered, and the hot and cold utilities are directly used for heating and cooling requirements, respectively. 

Heat integration, multiple feed and withdrawal, partial splits, and medium recoveiy fractions in distillation column sequencing. 

In the forward heat integration scheme (FHI) the top vapour of the prefractionator is used to heat the reboiler of the main column, and after condensation split in reflux and secondary feed for the main column (Fig. 11.19). The pressure in the prefractionator has to be high enough to ensure a temperature difference of minimum 10 K in the reboiler of the main column. In the reverse heat integration scheme (RHI) displayed in Fig. 11.20, the top vapour from the main column is used to drive the reboiler of the prefractionator. Note that this vapour is practically the pure component A. After condensation this stream is split in top product and reflux of the main column. 

LSR (Light-Split/Reverse Heat Integration). The entire feed is fed to the low-pressure column, with the bottoms product from the low-pressure column fed into the high-pressure column. Here, heat integration is in the direction opposite to that of the mass flow. 

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