SEPTEMBER
2014
LNGINDUSTRY
47
Xavier Guérif and Pol Dunoyer, GEA Batignolles
Technologies Thermiques S.A.S, France, offer an
alternative solution to enhance the performance of air
cooled heat exchangers.
S
aving on natural resources is becoming an increasingly important
topic in the contemporary plant engineering environment. Air cooling
is becoming the method of choice when it comes to the selection of
heavy duty cooling equipment for new installations in the oil and gas industry,
especially in the field of gas liquefaction. At the same time, plot of the cooling
equipments and concrete racks, power consumption of the fans, and steel
needed for the structure of the air cooler are all important factors when it
comes to the selection of the right cooling method.
Air cooled heat exchangers (ACHE) have already been widely used in the
petrochemical, oil refining, gas and power industries for decades. As the air is
not the most efficient fluid to exchange the heat, ACHE size is now becoming
a major issue in the plant environment. ACHE are commonly equipped with a
bundle of tubes surrounded by fins that are either wrapped, embedded or
extruded, allowing an increase in the heat exchange surface area by a factor of
up to 20 compared to the inner surface. The fluid to be cooled or condensed
flows inside the tubes and the air circulates around the fins forced by the
appropriate fan system. Typically, two or three axial fans are used to serve one
or two bundles (see Figure 1). This assembly is called a ‘bay’. For a given
thermal service, a combination of bays operate in parallel. All bays together
are called a ‘train’ (see Figure 2).
It is very common in the industry to increase the number of finned tube
rows in order to reduce the plot area, even if doing so decreases the efficiency
in the heat transfer. This is why there was significant demand for an innovative
solution to reduce the plot without decreasing the heat transfer efficiency in
the finned tube bundle. After deeper analysis of the topology of the air flow
inside the bundle, it is clear that large recirculation areas are located just
behind each of the tubes. These dead zones account for the very poor heat
transfer coefficient, meaning that these parts of the fins are not used for the
heat transfer.
After observing this phenomenon, GEA decided to investigate solutions
that benefited from this unused surface, thus resulting in the development of
the ‘groovy cooling technology’. The patented groovy cooling concept is
groove
Into the
