Constant-pressure flow splitter

Figure 1.9 illustrates the operation of a simple propane-butane splitter. The tower controls are such that both the pressure and bottoms temperature are held constant. This means that the percent of propane in the butane bottoms product is held constant. If the operator increases the top reflux flow, here is what will happen if... 

The flow cross-section within a given spiral channel is constant and at the designers discretion. A further important feature is that the effective disc area for heat transfer is enhanced by the inter-spiral walls which act as very efficient fins. From a mechanical point of view the spiral fins also serve to reinforce the disc surface so that it remains undistorted by the differential pressure forces between the heating channel and the process fluid - an inherent problem with the splitter plate design. 

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