There are two types of line heaters: Indirect and Direct fired. An Indirect-Fired Line Heater has a firetube immersed in a heat medium, such as glycol. The glycol heats up and transfers it’s heat through the coils; the desired product to be heated is passed inside the coils.
Direct-fired line heaters, the firetube is immersed in the product being heated (similar to how a Treater heats the emulsion). NRG specializes in Indirect-Fired Line Heaters.