Kettle Type Reboiler:

Kettle reboilers are commonly applied when a wide range of process operations (high turndown capability), large heat exchange surface, or high vapor quality is required.
Kettle reboiler is also called a “submerged bundle reboiler”. Installations include column bottom reboilers, side reboilers, or vaporizers. Kettles are generally more costly than other reboiler types due to shell size, surge volume size, and uncertainty in the TMTD.
They are often used as vaporizers, as a separate vapor-liquid disengagement vessel is not needed. They are suitable for vacuum operation and for high rates of vaporization up to 80% of the feed.
The kettle reboiler is an exchanger that has a tube bundle immersed in a liquid bath, with substantial vapor disengaging space above the vapor. Vapor and liquid are separated in the reboiler’s disengaging space, so the return line carries essentially vapor. Kettle arrangements are once-through systems; reboiler effluent liquid does
neither recirculate nor back-mix with bottom tray liquid.
Vaporization takes place on the outside of tubes immersed in a pool of liquid. The bottom product is taken from an overflow from the liquid pool and there is no recirculation between the reboiler and the column. In some designs, the tube bundle can be installed in the base of the column as an internal reboiler. The kettle reboiler incorporates a volume above the liquid pool and tube bundle for vapor and liquid disengagement.

Here some of design for kettle reboiler:

1. The shell diameter is typically 40% greater than the bundle diameter.
2. The height of the tube bundle is usually 40-60% of the shell ID.
3. Kettle reboilers are typically designed with an overflow weir, which creates a
separate liquid product compartment within the exchanger shell.