Aluminum plate-fin heat exchanger is a kind of high efficiency, compact and cryogenic heat exchanging equipment, with characteristics of complicated design theory, high fin molding precision and brazed to be a whole piece at one time, especially applicable to the cases of multi-stream or state changes during heat transfer.

Most brazed aluminum plate-fin heat exchangers have been installed in process plants used to separate a feed gas into its constituents, for example by the partial liquefaction of the feed and subsequent distillation and separation. The products and waste streams are then re-warmed against the feed streams. Condensers and reboilers are associated with distillation columns. Often chillers using standard refrigerants are used. Brazed aluminum plate-fin heat exchangers are well suited for these and many other services.

The major applications of brazed aluminum plate-fin heat exchangers have been in the cryogenic separation and liquefaction of air (ASU); Natural Gas Processing (NGP) and Liquefaction (LNG); the production of petrochemicals and treatment of offgases; large refrigeration systems.  

The maximum working pressure for brazed aluminum plate-fin heat exchangers can be over 100 bar g while also having a natural ability to accommodate a full vacuum design condition. Manufacturer dimensional constrains and thicker components are required at high pressures, however. It is possible to have over twelve process streams, at various pressures from minimum to maximum, in a single heat exchanger.

The maximum temperature rating is typically specified at 65°C. An upper limit of 65°C is suitable for most applications, and it allows manufacturers to use 5083 aluminum alloy piping which is more economical. However, designs are available for up to +204°C at lower pressures, and design temperatures in excess of 65°C are common. The minimum design temperature is -269°C. See Chapter 6 for a full material listing.

In general, fluids should be clean, dry, and non-corrosive to aluminum. Trace impurities of H ₂S, NH₃, CO₂, SO₂, NO₂, CO, Cl and other acid-forming gases do not create corrosion problem in streams with water dew point temperatures lower than the cold-end temperature of the brazed aluminum plate-fin heat exchanger. Under specific conditions, mercury can corrode aluminum and therefore caution must be used when handling mercury-containing fluids.

Proper filters (usually mesh filters) must be installed upstream of the heat exchanger system and maintained according to the filter manufacturers’ recommendations to prevent plugging from particulates such as pipe scale or molecular sieve dust. If a brazed aluminum plate-fin heat exchanger is accidentally plugged, proven cleaning procedures are available.

Fluids containing compressor lube oils, and other heavy hydrocarbons are acceptable provided these contaminants do not precipitate out on the fin surface. In the event of heavy fouling, chemical solvent cleaning of the exchanger is a proven method of cleaning.

Most governing jurisdictions require a pressure test of the piping system after a heat exchanger is installed. The test shall meet the requirements of the relevant code authority.  It is highly recommended that a pressure test is NOT conducted with water as the test medium. Water removal after the heat exchanger is installed is difficult and residual water trapped within the heat exchanger can freeze during unit operation causing serious damage and lead to premature failure of the heat exchanger.  Each stream of the heat exchanger system must be tested individually, with the other streams unpressurized. Oxygen-free nitrogen of dew point -40°C or better should be used as the test medium.

Zhongtai is at the forefront of industry for plate-fin heat exchanger design and manufacture, especially for high pressure, phase transition and multi-stream cores.  Zhongtai’s design always brings customers a minimum total investment for plate-fin heat exchanger.  At the moment, the highest design pressure of Zhongtai’s plate-fin heat exchanger is 9.28MPa, the biggest single core size is 1.3*1.2*8.5m and main heat exchangers are applied for the biggest ASU 6 trains of 820,000Nm³/h.  Zhongtai’s plate-fin heat exchangers, based on ASME code and PED, have been exported to 16 countries including USA, Russia, Europe and India, etc.