Vertical reboiler

Fixed Tube Sheet Both tube sheets fixed to shell Condensers liquid-liquid gas-gas gas-liquid cooling and heating, horizontal or vertical, reboiling Temperature difference at extremes of about 200°F. Due to differential expansion 1.0... 

Figure 10-97A. Heat transfer data of reboilers boiling a pure hydrocarbon at low pressure in horizontal and vertical reboilers. (Used by permission Yilmaz, S. B. Chemical Engineering Progress, V. 83, No. 11, p. 64, 1987. American Institute of Chemical Engineers. All rights reserved.)...

Fair s presentation provides the development of the design technique. The method recognizes two-phase flow in a vertical reboiler and points out that slug-type flow is most predominate and that mist-flow should be avoided. 

A vertical reboiler has very little piping and its length determines the height of the tower skirt. Supports at grade are saved but supports on the tower must be added. 

This is the driving force for vertical reboilers. Friction losses should be smaller than this. 

Figure 7-75. Relative elevation between the tower bottom and the bottom of a vertical reboiler.

In vertical reboiler circuits, reboiler losses are greater and pipe losses are smaller than in horizontal circuits. This often results in a difference of two pipe sizes between the downcomer and riser — also, in larger pipe sizes than in horizontal reboilers (assuming the same liquid, flow and evaporation rate). 

Figure 7-76 shows a vertical reboiler with a high draw-off nozzle. Using this figure, the driving force is ... 

It is good practice to provide tubesheet vents (134, 254, 358 Fig. 15.106) opposite the top vapor inlet nozzle in a vapor-heated vertical reboiler (condensing on the shell side). This is essential in steam reboilers, where a small steam purge should be continuously vented to atmosphere. Shell corrosion due to CO2 accumulation is known to have occurred in steam reboilers that had no such vent (234, 254). 

Before proceeding, after completing this example, it was brought to our attention that reboiler pumps are used normally with vertical reboilers, not with kettle reboilers. When appropriate to add a reboiler pump, or any other equipment item, to the mapping, the procedures in this section should be followed. 

An important feature to remember when working with tower-supported vertical reboilers, not requiring springs, is highlighted in Exhibit 6-17A. 

---