A heat exchanger is a system used to transfer heat between two or more fluids. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct contact.
JWW mainly uses the Hairpin style (Dehys), Gas to Gas Exchanger (Contactors), & Overhead Condenser (BTEX Unit)
There is a market for replacement Exchangers, as the tubes inside get plugged over time.