Hairpin Heat Exchangers
An efficient alternative to conventional shell and tube heat exchangers.
Hairpin Heat Exchangers use true counter-current flow. Unlike multi-pass shell and-tube designs where correction factors are used to account for inefficiencies resulting from counter current passes, this process maximizes temperature differences between shell-side and tube-side fluids.
Owing to having fewer sections and less surface area, a hairpin heat exchanger is the most efficient design when a process requires a temperature cross i.e. the hot fluid outlet temperature is below the cold fluid outlet temperature.
Process conditions particularly suited to hairpin heat exchangers:
- Process requires a temperature cross
- Applications with high pressure on the tube-side
- Cyclical service
- High flowrate ratios between shell-side and tube-side fluids
- High terminal temperature differences (300°F/149°C or greater)
- The exchanger is subject to thermal shock
- Heating or cooling vapors
- Complete vaporization is required
- Solids are present in the process stream
Double-Pipe and Multi-Tube Exchangers
Double-Pipe heat exchangers utilize a single pipe-within-a-pipe design and are commonly used for high fouling services such as slurries where abrasive materials are present, and for smaller duties. Standard shell diameters range from 2” to 6”.
Multi-Tube heat exchangers are used for larger duties with standard designs for shell diameters up to 30” and surface areas in excess of 10,000 ft2 per section. Free floating U-tube bundles allow for differential expansion and eliminate the need for expansion joints.
- Separate tubesheets handle large temperature differences and cycling duties more effectively than shell and tube units
- Durable baffle cage construction welded directly to the tie rods removes the need for sleeves or internal nuts
- Movable support brackets allow thermal expansion and contraction of the shell
- Tube- and shell-side connections are at the same end for simplified installation and pipework connection
- No inetrnal bolting
- Double-pipe exchangers utilize pipe instead of thin wall tubing for enhanced integrity
Heat Transfer Augmentation
Longitudinal ﬁn pipes and ﬁn tubes provide augmented heat transfer surface area for both double pipe and multi-tube hairpin exchangers. This provides further space saving in applications where the shell side heat transfer coefﬁcient is the limiting factor, for example with low pressure gases and highly viscous ﬂuids.
IMB has also engineered peripheral bafﬂes that further enhance extended surface effectiveness, without increasing pressure drop.
Clean Energy Applications
Hairpin heat exchangers are the preferred design to withstand the demanding process requirements associated with increasing capacity at LNG storage and processing plants. IMB has a proven track record in this field with the design and manufacture of large units (ND > 20").
Twin 28" and 33" ND IMB multi-tube heat exchangers replaced eight conventional shell and tube units at two concentrated solar plants, delivering investment cost savings, together with more efficient performance and reduced maintenance.
Hairpin heat exchangers are also widely used in oil and gas processing.