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 co-current passes, this process maximizes temperature differences between shellside and tubeside fluids. Owing to its fewer sections and less surface area, a hairpin heat exchanger is the most efficient design, when a process requires a temperature cross (hot fluid outlet temperature is below cold fluid outlet temperature).
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.
When to use for Hairpin Heat Exchangers
The process results in a temperature cross.
High pressure tubeside application.
High flow rate ratios between shellside and tubeside fluids.
High terminal temperature differences (300°F/149°C or greater).
The exchanger is subject to thermal shocks.
Heating or cooling vapors.
Complete vaporization is required.
Solids are present in the process stream.
Why Hairpin should be preferred
Separate tubesheets: Handle high temperature differences and cycling more effectively than shell-and-tube exchangers.
Durable baffle cage construction: Welded to the tie rods without the need for “sleeves” or internal nuts.
Moveable support brackets: Allow shell expansion and contraction and eliminate the need for sliding plates commonly used for fixed supports. Brackets are slotted for anchor bolts on all four sides for flexibility in installation, and offer the ability to add sections in the future.
Easy installation and piping, as tubeside and shellside connections on the same end.
No internal bolting.
Double-pipe exchangers utilize pipe instead of thin wall tubing to enhance integrity.
Our closure designs offer an effective means of providing a removable tube bundle for a variety of design conditions and applications. All of our closures have the following features:
External Split rings – Split rings are used to lock the bundle to the shell. On outdated models these rings were internal and came into contact with the shellside fluid. Internal split-rings are still used by others.
Better gasketing – Our gaskets do not seat on the tubesheet face where misalignment easily can occur and the potential for erosion exists. Our shellside gaskets are easier to remove than wedge gasketing used by competitors.
Separate tubeside and shellside gaskets – Prevent interstream leakage.
Round flanges – More effective gasket seating than square flanges.
Hairpins with finpipes
Double pipe exchangers and multitube hairping exchangers with longitudinal fin pipes and fin tubes, provide augmented heat transfer area in a compact arrangement, allowing effective space savings for applications where shell side heat transfer coefficient is limiting, as with low pressure gases and high or very high viscous fluids.
The adoption of IMB’s peripheral baffles can further enhance extended surface effectiveness, while keeping pressure drop very limited.
Oil & gas processing
Gas storage / LNG