The liquid is fed by means of a pump. Forced circulation reboilers with vertical or horizontal tubes boiling may be designed. Forced circulation reboilers are similar to vertical thermosiphon reboilers, except the pump is used for the circulation of the liquid and the hot liquid flows inside column. To calculate the heat transfer coefficient it is generally assumed that, heat is transferred only by forced convection. The usual method of shell and tube exchanger design can be used.
Advantage: suitable for viscous and highly fouling fluids.
Disadvantage: high pumping and maintenance cost; pump is required to circulate the boiling liquid through the tubes and back into the column.