Reboiler sizing screen
Quick screening of reboiler area by type — kettle, thermosyphon (vertical and horizontal), forced circulation and plate — using typical overall-U ranges, LMTD and a wall-temperature check.
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Results
Heat Exchanger Excel kit
Shell and tube performance, fouling, LMTD and NTU rating, condenser and reboiler performance, plate exchanger — with print-ready reports, any units and visible formulas.
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How this calculator works
This is a screening tool, not a full thermal design. It takes the reboiler duty, the heating-medium conditions and the boiling temperature and estimates the required heat-transfer area for each common reboiler type using published ranges of overall heat-transfer coefficient U. The result is a band (low U to high U) so you can see which types are feasible and roughly how large each would be.
LMTD is calculated as isothermal for steam and fired heaters (the medium temperature is constant, so LMTD = Tmedium − Tboil) and as a true log-mean for hot oil (where the oil cools from inlet to outlet against the constant boiling temperature).
The wall-temperature check estimates the tube-wall temperature as the arithmetic mean of the medium and process temperatures. If this exceeds the maximum allowable wall temperature you enter, the reboiler type is flagged. This is a crude screen — in practice, the wall temperature depends on the film coefficients on each side, fouling, and the tube-wall resistance — but it catches the obvious cases where a high-temperature medium would overheat a fouling-sensitive fluid.
Typical U ranges are from GPSA, Perry, Kern, and HTRI published guidelines. The actual U depends on the fluid, fouling, geometry and operating conditions, so treat the bands as ±30 % screening estimates.
Limits: This screen does not account for nucleate-boiling flux limits, circulation rates, two-phase pressure drop or column hydraulics. A full reboiler design needs a proper thermal rating (e.g. HTRI or BJAC) and a hydraulic check of the thermosyphon loop.