The equipment is designed to increase the temperature of Hydrocarbons (liquid or gas) through heat (energy) exchange. There are two kinds of pre-heaters:
Water bath heaters: Heat is generated in a fire chamber with fuel (eg: natural gas). This heat is transferred to a Water Bath where a coil is immersed. The fluid to be heated flows into this coil. Heat is then transferred from the water to the Hydrocarbon. This is indirect heating.
Fire Heaters: The fluid (natural gas etc.) is in direct contact with the Fire Tubes. These can be of the horizontal or vertical design.
Heaters are used to increase separation efficiency, reduce the viscosity for oil transportation, and increase the gas temperature to avoid condensations in pipe-work (Dew Point).