Natural gas liquefaction plants are the biggest single users of AFC's today. One example will clearly describe the situation: on a 4 MMTPA liquefaction train based on the Air Products C3MR process, the largest service is the propane condenser which will reject approx. 200 MW into the atmosphere resulting in a ca. 200m long AFC.
The first air cooled LNG plant was started up in 1989 in Australia but water cooling remained dominant, being used for Technip’s projects in Nigeria LNG (trains 1, 2 & 3), Yemen LNG and the Qatari AP-X mega trains.
The shift to AFC’s results from the drive to lower project costs, the growing importance of plant reliability and the regulatory preference for air cooling that avoids any impact on the aquatic environment. However, despite this shift, AFC technology has changed little over time.
In 2007, Technip and Wieland were starting to see the trend that today means the GEWA-PB tube is the dominant solution for propane evaporators and the efficiency of GEWA-KS dual enhanced tubes in the water cooled propane condensers of all six AP-X trains in Qatar was on the way to be demonstrated. However, it was realized that with few exceptions all future onshore LNG plants were going to be air cooled.
There was a strong desire to transpose the GEWA-KS success to an air cooled equivalent. This resulted in the partnership with GEA-BTT, the leading supplier of AFC’s for LNG and which was quick to see the opportunity of creating a new industry-leading product.
DIESTA is quite simply a better exchanger. The improved heat transfer performance can be used to reduce the equipment size, to increase capacity, or to save energy.