Kaeser boosters in the German Aerospace Center (DLR)
German Aerospace Center (DLR)

Carbon fiber – nothing burns.

Compressed air and nitrogen supply from KAESER for the research autoclaves.

The center for lightweight production technology at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR) researches time-saving methods for the fully-automated mass production of super-lightweight carbon fiber components. Heavy equipment. With Kaeser expertise.

Whether for airplanes, cars or bicycles, lightweight construction is essential when it comes to making advances in energy efficiency. Carbon-fiber reinforced polymers (CFRP) are expected to play a major role in this endeavor.

The DLR’s Center for Lightweight Production Technology(ZLP) in Stade is looking for practical ways to mass-produce high quality CFRP components (up to 100,000 units per year) and make them more affordable for a greater number of applications. The ZLP aims to convert the theoretical knowledge gained at the laboratory level to an industrial scale and to examine non-scalable effects using original size components. In order to do this, the applications are fully simulated. This takes place in the research autoclave.

Compressed air and nitrogen supply from KAESER for research autoclaves
A colossus – the largest research autoclave in the world.

An autoclave is an oven in which materials are fused at high temperature under pressure; in other words it really does work like a pressure cooker. It can be used, for example, to make and analyse complete aircraft fuselage components, wings or rudders. With an external length of 27 m, and external diameter of 6.50 m, the 181 tonne tube is an imposing sight.

Transport – a logistical challenge.

The autoclave had to be transported from its manufacturing site in Coesfeld to Stade. The first stop was the inner harbor at Coesfeld. The autoclave was loaded onto a ship, which transported it over 300 km to Stade. After being transferred to a heavy-load transporter, the “pot” finally crossed the A26 autobahn, which was closed specifically for this purpose.

The autoclave – a “pressure cooker” that uses compressed air and nitrogen.

The research autoclave operates at 420° C. At these temperatures, there is a risk that the research objects inside could ignite. This is why nitrogen is used, which acts as a protective gas, and prevents the components from burning.

This is where Kaeser plays a key role: Compressed air is broken down into its constituent parts of nitrogen and oxygen in a Kaeser nitrogen generator.

First, the air is dehumidified in a desiccant dryer (DC 169 E) before being compressed to 35 bar by the booster. Two further refrigeration dryers (THP 142-45) and two microfilter-activated carbon adsorber combinations ensure that only dry and highly-purified compressed air flows into the nitrogen generator.

Forming the second stage of the compressed air system, two CSD 125 SFC (75 kW, variable speed) rotary screw compressors alternately feed a 9.5 bar compressed air system or three N 502-G 9.5/ 35 bar reciprocating boosters.

The nitrogen is then stored at 30 bar in two air receivers each with a capacity of 200 cubic meters.

The compressed air in the 9.5 bar system - dried in a TF 251 energy-saving refrigeration dryer and purified in a microfilter-activated carbon adsorber combination - is used to operate air cushion transporters that can handle payloads of up to 70 tonnes – because efficiency and performance are Kaeser specialties!