How does a reboiler heater work?
In distillation processes, a liquid that is often composed of different components (e.g. light and heavier hydrocarbons) is drawn from the distillation column into a reboiler, where partial or full boiling occurs. As a result, a vapour of lighter components is produced and returned to the column to drive the distillation separation. The reboiler is positioned at the base of the distillation column to supply the heat. The condenser at the top of the column removes the heat supplied to the column by the reboiler at the base of that column.
Types of reboiler
There is a wide variety of types of reboiler suited to different applications. We can design and manufacture the below reboiler types.
Kettle reboilers
Kettle reboilers allow heating fluid to pass through the tubes that are covered in the liquid, which needs to be distilled.
Steam (often used as a heating medium) or any other heating fluid (such as thermal oil), flows through the tube bundle and exits as condensate while the liquid from the base of the tower flows through the shell side. The tower processes and collects the vapour; the liquid by-product drops to the bottom of the kettle and is withdrawn as per the process design.
Benefits of the kettle reboiler.
- Simple and reliable.
- Suitable for vacuum operation and high vaporisation rate up to about 80% of the feed.
Sterling TT designs and manufactures bespoke kettle reboiler heat exchangers to suit your specific application.
Fired reboilers
A fired reboiler is a pressure vessel filled with process fluids and has tubes running through the vessel. The tubes heat the process fluids as per the process requirements. A pump is required to circulate the column liquid through the heat transfer tubes.
Benefits of the fired reboiler:
- Lowest upfront cost, depending on the construction and installation.
- The maintenance routine is simple.
- Cost-effective heating solution.
Forced recirculation reboilers
A forced circulation reboiler requires a pump to push the liquid to circulate through the reboilers. Depending on the process liquid, this is useful as the flow may be either once-through or recirculating. We can locate this reboiler type far from the main column.
Benefits of the forced recirculation reboiler:
- Suitable for viscous and highly fouling fluids.
- The reboiler can be located far from the column. In that case, we need to add a pump.
Thermosyphon reboilers
There are two primary types of thermosyphon reboiler: vertical or horizontal. The kind of thermosiphon used will depend on the orientation of the heating fluid tubes and the flow of the liquid. These reboilers work on a simple principle based on the difference of densities of liquid and vapour for recirculation between the outlet and inlet line. We don’t need an external pump to inject the vapour into the column.
Benefits of the thermosyphon reboiler:
- Most economical because no pump is required.
Stab-in bundle reboiler
Stab-in bundle, also known as internal reboiler, is a kind of reboiler where a tube bundle is inserted into the bottom of a distillation column. The steam or any other heating fluid will enter the bundle and boil off the liquid occupying the column bottom. Due to column diameter limitations, this method is used for smaller duties and reboiler sizes.
Sterling TT designs and manufactures various types of reboilers to suit specific applications. Simply get in touch to discuss your requirements.
Reboiler design considerations
When selecting a reboiler heater, you need to make some critical choices. These include whether to vaporise on the shell side or tube side, rely on gravity flow or forced flow, orient the unit vertically or horizontally, opt for a flow-through or kettle design, or install baffles inside the tower.
We will work with you to discuss your requirements and design the optimal reboiler heat exchanger for your process.
Coming up with an optimal heat exchanger solution for your application is a complex challenge that requires expert insight. With over 100 years of experience in this sector, Sterling Thermal Technology is the perfect reboiler manufacturer to maximise the efficiency of your process.
