Eco friendly scrubbingtimes four

In two scrubbing stages, the gas scrubbers from Körting neutralise acids - and do so for longer than planned, thanks in part to the high product quality.

High resistance thanks to special plastic

The International Space Station (ISS) is the oldest space station to date. Construction started in 1998 and it’s still in use today. At a west German chemicals group, machinery with Körting gas scrubbers has been running for virtually the same length of time. And longer than originally planned thanks, in part, to superior quality. After just under 25 years in operation, they’re now being replaced by four new ones. “We’ve been collaborating with the customer on a wide range of ventures for a very long time. The manager approached us with this project and ordered not three, but four scrubbers, which are identical in terms of process engineering,” comments the engineer concerned.

They are made of carbon steel and painted on the outside. At 2.80 metres in height and 800 mm in diameter, they’re relatively small, but sophisticated nevertheless. Each is coated on the inside with a special plastic called ECTFE, a polymer that, like Teflon, isn’t attacked by most acids and has good thermal resistance and non-stick properties. But why is the carbon steel tank lined with plastic and not made entirely of plastic in the first place? If a scrubber is normally operated at atmospheric pressure, it's a pressure vessel designed for three bar overpressure in this case.

Customised solution for optimal conditions

The system’s job is to remove sulphur dioxide (SO2) and hydrogen chloride (HCl) from the process stream. Caustic soda (NaOH) allows incoming components to be neutralised and cleaned. The gas flows through two scrubbing stages in a row. In this case, the motive fluid serves as the scrubbing medium and is injected into the jet scrubber from top to bottom in the same direction as the gas. Packing material is added to the second apparatus and the flow is again from bottom to top. “This packing material has little volume but a large surface area. It’s selected based on the application concerned, the material and requirements. The purpose is to create the largest possible mass transfer area,” explains Körting’s project engineer.

The project is scheduled to take 12 months. This customised solution, is, of course, underpinned by both parties working together as a team. “We’re focusing on working with the customer for a long time to come,” stresses Körting’s head of the technical sales department. While the ISS will be decommissioned for technical reasons by 2030 at the latest, Körting’s gas scrubbers are still going strong.

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