Special materials used to solve corrosion problems

Many process engineering applications with corrosive media require the use of non-metallic materials. Only very few equipment manufacturers are up to this complex challenge – and Körting Hannover GmbH is one of them.

Exceptionally corrosive

Körting built two graphite vacuum systems for use with hydrochloric acid (HCl) gases for a company in Asia for the second time in quick succession. The engineering, planning, performance testing of the jet ejectors on the in-house test rig and the final assembly were all carried out in Hanover, Germany.

The initial planning of two vacuum systems took place in January 2020. The outstanding quality quickly prompted a follow-up order for two more identical vacuum systems to complement the customer’s existing machinery. “Strictly speaking, this is a three-stage system with intermediate and after-connected surface condensers,” comments the project engineer in charge. Via the first jet ejector stage, the acid gas is sucked in at 10 mbar absolute pressure from glass-coated feed pipes and compressed to ambient pressure via the two further stages. Because the gas is highly corrosive, conventional metallic materials can’t be used. Consequently, this factor is a huge benefit compared with conventional mechanical vacuum pumps that require metallic materials.

Hanover-based quality control

The task is so complex due to the material the vacuum ejectors are made of. Graphite is a brittle material, so special care must be taken when transporting it or during assembly. Consequently, Körting graphite vacuum ejectors are supplied pre-mounted on a frame and all external graphite nozzles are fitted with PTFE (polytetrafluoroethylene) bellows. As a result, customers don’t come into contact with the sensitive graphite components. And it’s easy to position the equipment by using the transport securing devices on the frame. We liaised closely with our long-standing local partner to give the customer the best-possible advice and customise the size of the equipment. The customer was even more satisfied because the vacuum system’s performance wasn’t just received in theory, but in practice too.

“At the design phase, to minimise the space required to transport and time taken to install it, we ensured the vacuum system was compact. Basically, the customer can use it virtually out of the box,” explains the project engineer. “The last step was to connect the pipes to the compensators. All the customer had to do was connect the pipes to the skid unit. The vacuum ejector was then ready to go straight away.”

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