Kettle reboilers are very simple and reliable. Kettle reboilers may require pumping of the column bottoms liquid into the kettle, or there may be sufficient liquid head to deliver the liquid into the reboiler. In this reboiler type, steam flows through the tube bundle and exits as condensate. The most critical element of reboiler design is the selection of the proper type of reboiler for a specific service. Most kettle reboilers are of the shell and tube heat exchanger type and normally steam is used as the heat source in such reboilers.
Kettle reboilers transfer fluids like hot oil or Dowtherm may be used. Kettle reboilers furnaces may also be used as reboilers in some cases.The liquid from the bottom of the tower, commonly called the bottoms, flows through the shell side. Kettle reboilers is a retaining wall or overflow weir separating the tube bundle from the reboiler section where the residual reboiled liquid called the bottoms product is withdrawn, so that the tube bundle is kept covered with liquid.