Screw Heat Exchanger Keeping Itself Clean

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KÖLLEMANN GmbH

Unfortunately, these machines required a lot of maintenance and also complex control systems to prevent the flights from touching (and damaging) each other. Köllemann’s aim of creating machinery with unbeaten records of reliability and safety led them to dismiss this design.

The second attempt resulted in the machine that is currently in production. This features a twin-shaft design in which the shafts rotate in the same direction at relative speeds in the ratio 2:1. Narrow gaps between the flights maximize shear forces within the conveyed material. Thanks to the co-rotating design, the flights on each shaft constantly remove adherent material from those on the other shaft.

The 2:1 speed ratio is achieved through an extremely rigid gear that provides accurate mechanical synchronization without the need for external control systems.

Manufacturing Challenges

Even though the new design is both effective and reliable, it is still challenging to manufacture. The large number of weld seams require a correspondingly large heat input, which in turn causes the shaft to shrink in length. To ensure a perfect fit with a narrow gap between the flights, both shafts are therefore fabricated side by side and flight by flight. The result is a precisely matched pair of shafts.

For Specific Requirements

Like all screw heat exchangers from the company, the self-cleaning design can utilize a wide variety of heat exchange media — typically water, oil, steam, or brine. Other options such as modular insulation covers, flow controls, rotation monitoring and nitrogen blanketing can also be installed. The company offers almost 50 years of experience in the design and manufacture of screw heat exchangers. The biggest preheaters for calcined petroleum coke are also built by them. Every machine is designed and manufactured to suit the specific process requirements, including a wide range of construction materials.

* * Matthias Ginster is Head of the Project Department at Köllemann GmbH, Adenau/Germany. Contact: Phone +49-2691-308-50

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