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Edition 03/2019

Article and compact news

Our AERZEN customer journal "AERZEN" will provide you with detailed information at regular intervals about our company, our products and application solutions.


Under pressure: tunnelling in groundwater

Aerzen Rental establishes itself as a competent partner for preliminary application

In Karlsruhe, an underground tram line is being built between Ettlinger Tor and Marktplatz. The tunnel, which is just over 300 metres long and passes through the centre of the city, is challenging because of its special geological formation. To prevent water penetrating into the construction site, the company Pressluft Frankfurt Drucklufttechnik GmbH relies on our compressor technology.

In Karlsruhe, the eight CVO4400 units of Aerzen Rental are combined into two-storey units to save space.

Anyone who stands on Karl-Fried-rich-Straße in Karlsruhe during a downpour and takes a look at the asphalt will notice a fine-pearled foaming road.  The reason: the tunnel underneath, with its base 15 metres below street level, loses air. “Here, we have to deal with a lot of sand, gravel and loose rock. These are materials which are not useful in tunnel construction,” says Robert Schweitzer, Construction Manager, describing the challenges he faces in the centre of Karlsruhe.  On one side, due to the geological conditions, BeMo Tunnelling GmbH is forced to stabilise the walls by propelling shotcrete at them, as otherwise the ground could behave unpredictably. On the other side, the pores are so large that the ground water would run directly out of the walls if the appropriate counterpressure is not provided on site. This leads to the conclusion that the work is literally under pressure. In the first construction phase, this is at a delta of 0.75 to 0.85 bar to the atmosphere. Therefore, the project is subject to German compressed-air regulations which define the relevant rules regarding job safety. Against this background, nobody is permitted to enter the pressure lock without a special briefing - and must not leave it without decompression taking place. 

The pressure sluice supplies data to a control room where the sluice monitor always has an overview of the operating status of all compressors on a display.  Twelve assemblies are installed - four underground and eight on the road directly above. The spatial division is due to the fact that soil analyses undertaken at the beginning of the tunnel project suggested a higher degree of impermeability. This assessment subsequently proved incorrect and thus the flow capacity which had been calculated for the compressors did not apply either. “Making forecasts for old riverbeds is almost impossible.” We simply do not know what to expect”, says Peter Engelke, project manager of Pressluft Frankfurt. The company received an order from BeMo to design the compressed air according to the initial soil analysis in the Rhine plain.

Efficient and quickly available solution

Four compressors - initially provided for underground work - are not sufficient to reliably prevent the groundwater from penetrating, due to the sandy soil.

As it soon became clear that the calculated performance would not be sufficient, Pressluft Frankfurt and Aerzen Rental started looking for an efficient solution that would be quickly available. “The cooperation between all three companies is quite flexible and very professional”, emphasises Engelke.  

“We have integrated the compressors with Delta Screw packages (VM 60, 1.140 to 4.550 m³/h, 45 to 250 kW) as core within container frames. These can be easily transported, combined to form space-saving units on site and, thanks to the cartridge design, can also be stacked on top of each other,” explains Peter Link who is responsible for the German rental business. The headquarters of Aerzen Rental is at Duiven in the Netherlands. In Karlsruhe, the compressors type CVO4400 are combined with water coolers which cool down the air outlet temperature of the compressor from 120°C to 20°C. 

Efficient reserves are required

During the not so deep work, the assemblies pump 100 to 140 cubic metres of air per minute into the tunnel on a daily average. This also explains the foaming road when it rains. The deeper the site is, the more the pressure increases from the groundwater. Robert Schweitzer expects a pressure delta of up to 1.3 bar by the end of the structural work. Therefore, the pressure losses will increase exponentially and a higher volume flow will be required. For this reason, and according to the compressed air regulations after sufficient redundancy, the equipment supplied by Aerzen Rental covers adequate reserves. “We have to cover the complete demand by two thirds of the installed machine performance. Four of the twelve assemblies serve as spare machines”, explains the mechanical engineer. “The specific performance of the assemblies is unrivalled,” emphasises Engelke, describing the start of cooperation between AERZEN and Pressluft Frankfurt more than 30 years ago. “In all these years, I have never had a broken machine - this signifies long working life and reliability.” 

In Karlsruhe, the speed of the compressors is adjusted so that their actual performance corresponds exactly with the pressure losses from the tunnel - these measure 15,000 cubic metres from Marktplatz to Ettlinger Tor. In addition, it is economical for BeMo Tunnelling and Pressluft Frankfurt to rent these compressor packages in such special application cases, instead of buying them. And the independent Aerzen Rental service takes care of all the maintenance during the time that the equipment is in operation.

Compact news

AERZEN is World Market Leader

AERZEN is World Market Leader

Big thumbs-up from Wirtschaftswoche: In a study, the renowned German business magazine has found out that AERZEN is the world market leader 2020 in the field of “Positive Displacement Blowers and Screw Compressors”.

The economist Prof. Christoph Müller, from the University of St. Gallen in Switzerland, has developed a robust assessment procedure for the magazine, on the basis of which he draws up a list of world market leaders every year.

Wirtschaftswoche published a tabular overview of the 450 companies with turnover and sectors in which they dominate in a special issue dated 14 October 2019.

“Star of Product” for AERZEN Delta Hybrid

Aerzen China received the award “Star of Product” for the rotary lobe compressor Delta Hybrid at the 14th International Water Conference in Qingdao, China. The event took place from 25 to 28 June 2019. A total of 20 companies were nominated for the award. AERZEN won due to the outstanding performance, reliability and economical energy consumption of the Delta Hybrid. Lang Weiguo, Sales Director Aerzen China, accepted the award on behalf of the company. Tony Chien, Sales Manager Aerzen China for the water industry, gave a lecture on energy savings and new developments in blowers for wastewater treatment.

Aerzen China participated for the second time in the water conference in Qingdao and has already confirmed its participation for the next year. More than 2,500 participants showed great interest in the company’s energy-saving solutions and products. The China Association for Science and Technology and the Qingdao Municipal People’s Government are the hosts of the event.

Aerzen Turbo Korea successfully validated for US-American CTPAT programme

Aerzen Turbo Korea successfully validated for US-American CTPAT programme

Thanks to the successful re-validation of Aerzen Turbo Korea as a foreign supplier, Aerzen USA can continue its participation in the CTPAT programme. CTPAT, which is the Customs Trade Partnership Against Terrorism, is intended to strengthen international supply chains and improve border security in the United States. Every four years the re-validation of a supplier abroad becomes necessary, in this case Aerzen Turbo Korea. Aerzen USA has been participating in this programme since 2016, which brings considerable advantages for the import of goods. For example, CTPAT members are subject to fewer customs inspections and waiting times at the border for the import of products are reduced.

Craig Russell leads the Middle East and Africa

At the beginning of September 2019, Craig Russell took over as Managing Director of Aerzen Gulf and Head of the Middle East & Africa. Born in Scotland, he will lead the AERZEN Group in the Middle East and Africa from Dubai and sees great potential in the region: “Taking over responsibility for the Middle East and Africa is a privilege for me,” says Russell. “The emerging markets generally offer us numerous opportunities, and this region is definitely already very successful. I support many of the initiatives that have already been launched, such as the expansion into East and West Africa and the development of local production.”

Russell has lived with his wife and two children in Dubai for many years, where he initially worked for American and Japanese family businesses in the food processing and packaging industries and later was responsible for the restructuring and sale of engineering companies.

New Head of Supply Process Gas

Walter Reiter has taken over the global management of Supply Process Gas at AERZEN and succeeds Pierre Noack. Reiter has over 30 years of experience in management positions in German plant and mechanical engineering companies.

New Head of After-Sales

Björn Heuer took over the management of After-Sales from Bernd Brakemeier on September 1, 2019. With more than 25 years of professional experience, including time as service engineer and product manager for Delta Blower and Delta Hybrid, he has extensive practical experience as well as in-depth product and application knowledge. For the past five years he has been responsible for the After-Sales Field Service division.