Pumparound purpose

The purpose of the pumparound is to cool and partially condense the upflowing vapors. The vapors to pumparound tray 10 are at 600°F. The vapors from the pumparound return tray 9 are at 450°F. There are two pumparound trays (9 and 10) in the column. This is the minimum number used. A typical number of pumparound trays is two to five. 

Another purpose of the pumparound is to suppress top-tray flooding. If tray 1 in Fig. 12.2 floods, the operator would observe the following ... 

Direct-contact condensers (Fig. 15.14f). These are used for minimizing pressure drop in vacuum condensation. To accomplish this, the direct-contact zone contains low-pressure-drop internals such as packings, or is a spray chamber. Another common application is intermediate heat removal ("pumparounds ) in refinery fractionators. Here the main purpose is to maximize heat recovery at the highest possible temperature levels. A third common application is intermediate heat removal from absorbers or reactive distillation columns in which an exothermic reaction takes places. In all these applications, condensation... 

Here we examine another application of nonadiabatic columns - to decrease energy consumption in separation. Nonadiabatic columns are widely used for this purpose in petroleum refining (heat output by pumparounds ). 

The manufacture of distillates either directly for fuels or for feed to downstream processing units ordinarily does not require any particular degree of fractionation between cuts. Also, wide cuts are usually acceptable. For these reasons, the distillates can be condensed by cooled pumparound reflux, grid type contacting sections and chimney draw trays. For all practical purposes, the operation of the main condensing sections can be described as a single-stage equilibrium condensation. 

For the purposes of the illustrative design procedure, the pumparound heat removals were assumed on the following bases. 

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