Reboiler design

The modified Palen-SmaU method can be employed for reboiler design using finned tubes, but the maximum flux is calculated from A, the total outside heat-transfer area including fins. The resulting value of refers to A. ... 

Type 77 units are the condenser and reboiler designs. One side is spiral flow and the other side is in cross flow. These SHEs provide veiy stable designs for vacuum condensing and reboiling seiwices. A SHE can be fitted with special mounting connec tions for refliix-type vent-condenser apphcations. The vertically mounted SHE directly attaches on the column or tank. 

Collins, Gerald K., Horizontal-Thermosiphon Reboiler Design, Chemical Engineering, July 19, 1976. 

Fair, J. R., Vaporizer and Reboiler Design, parts 1 and 2, Chemical Engineering, July 8 and August 5, 1963. 

TheiTnal decomposition, caused by an excessive reboiler temperature (over 404°F), deposits on the firetube, or a poor reboiler design. 

In reboiler design, film boiling should be avoided. However, such rules-of-thumb as 10-12,000 Btu/(hr) (fti) maximum heat flux are frequently quite conservative. 

Several other excellent presentations exist on the subject of reboiler design. Presenting all of the variations here is just not possible designers should refer to Hughmark, Palen and Taborek, Palen and Small, Frank and Prick-ett, and Hajek. ... 

General Guides for Vertical Thermosiphon Reboilers Design... 

In the nucleate boiling region the heat-transfer coefficient is dependent on the nature and condition of the heat-transfer surface, and it is not possible to present a universal correlation that will give accurate predictions for all systems. Palen and Taborek (1962) have reviewed the published correlations and compared their suitability for use in reboiler design. 

The critical flux in forced-convection boiling is difficult to predict. Kern (1950) recommends that for commercial reboiler designs the heat flux should not exceed 63,000 W/m2 (20,000 Btu/ft2h) for organics and 95,000 W/m2 (30,000 Btu/ft2h) for water and dilute aqueous solutions. These values are now generally considered to be too pessimistic. 

In a tube bundle the vapour rising from the lower rows of tubes passes over the upper rows. This has two opposing effects there will be a tendency for the rising vapour to blanket the upper tubes, particularly if the tube spacing is close, which will reduce the heat-transfer rate but this is offset by the increased turbulence caused by the rising vapour bubbles. Palen and Small (1964) give a detailed procedure for kettle reboiler design in... 

COLLINS, G. K. (1976) Chem. Eng., NY 83 (July 19th) 149. Horizontal-thermosiphon reboiler design. 

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