Air Cooled Heat Exchangers

Technical

Quality

Construction

Tube Bundles

Technical

Complete air cooled heat exchangers are thermally and mechanically designed taking into account the performance requirements, design codes and specifications, plot size, noise limitations, safety and maintenance requirements. The supporting steel structure design considers factors such as vibration, winds and earthquakes. Air coolers can be supplied in horizontal or vertical arrangement. Trial assembly in works, supervision of site assembly and commissioning is undertaken.

Air coolers are used to dissipate heat in many applications from water cooling to condensing overhead fractions. They are predominantly used in the petroleum refining, petrochemical, chemical, gas, steel and power generating industries.

Air coolers have a number of advantages compared to water cooling, the most important being:

Unlimited resources of air.
Location irrespective of large quantities of water.
Easy leakage location.
Improved level of environmental protection.
Tube corrosion from cooling medium.
Contamination of the product with cooling water.

Quality

Air coolers are manufactured in accordance with a certified quality system conforming to ISO 9001. Fully qualified inspectors ensure that clients' requirements, necessary codes/standards and internal procedures are strictly followed. Third party inspection authorities frequently visit and the works is approved by all the major inspection authorities:

UDT
TUV
Lloyds' Register
SLV
ASME U Stamp

Construction

Typically an aircooler is made up of one or more tube bundles mounted on a supporting structure with fans and motors. Air coolers comprise:

Tube bundles with finned tubes mounted into headers supported within sideframes.
Fans
Motors
Louvres
Steam coils and circulation housing
Steel supporting structure
Plenum chamber, fan decks, fan rings
Service platforms, handrails and ladders

Tube Bundles

Tube bundles can be supplied with various types of finned tubes and headers to suit the operating conditions and clients' specifications.

Finned Tubes

Finned tubes having aluminium fins are the preferred and most economical option. The main types of finned tubes are G type, L type, KL type, LL type, extruded and extruded serrated. A bundle is normally made up of several rows of finned tubes supported on cast zinc collars, cast aluminium collars, zinc rings, folded aluminium box supports or aluminium bands.

Headers

The finned tubes are connected to headers. Header construction is dependant on the process conditions and clients requirements. There are 4 main types of header:

Plug/box type - a welded box with accesss plugs.
Cover plate type - a welded box with a removable flanged cover allowing access to the inside of the header and tube ends.
Welded D type - a welded half tube or folded plate either removable or completely welded.
Manifold or tubular type - a pipe with finned tubes connected to stub pipes, used in high pressure applications.

Material for headers is in accordance with clients' requirements - carbon steel, alloy steel, stainless steel, duplex stainless steel.

Fans

High performance axial flow fans are required to move air across the bundle. Fans can be supplied with aluminium blades or glass-fibre-reinforced polyester blades and driven by electric motors and belt transmission or gearbox. Manual or autovariable fans can be supplied. The noise specification usually determines fan material selection and process operating requirements determine fan type.

Louvres

Louvres can be supplied which provide additional control of the cooling process and circulation of air. Louvre blades are supplied in aluminium or galvanised steel. Louvres are controlled remotely by means of an electric or pneumatic servo actuator or manually by a hand lever.

Steelwork

Steelwork is designed taking into consideration the loads, thermal forces, vibration, wind, snow and seismic effects. Fireproofing of steelwork is possible.The structure is made of rolled sections. Plenums and fan decks are typically a panel/bent plate construction. Header access platforms, walkways and ladders are of steel construction. Materials are normally carbon steel or low alloy structural steel (for extremely cold ambient temperature). Steelwork is protected by galvanising or painting to clients' specifications. When required trial assembly is carried out in works. Site supervision and commissioning can also be provided.