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Edition 02/2018

Article and compact news


Pneumatic conveying: Knauf and ISS rely on screw compressors made by AERZEN

At the Knauf site Rottleberode AERZEN screw compressors type Delta Screw are used for the pneumatic transport.

Knauf has recently invested around €33 million in the Rottleberode site in the southern Harz region - and in 2017 a modern fibreboard plant was taken into operation. Cellulose and stucco are the main components of the boards, which are very versatile in interior design applications. A pipe system is used to transport the fired and finely ground natural stone between the gypsum and fibreboard plants. AERZEN screw compressors type Delta Screw provide the appropriate pressure and volume flow during pneumatic transport.

The energy revolution will make the gypsum industry increasingly dependent on natural stone deposits in the future. The entire industry is in a state of upheaval, because the FGD gypsum produced in the desulphurisation plants of lignite-fired power plants is a dying breed due to the shutdown of these power plants. On the other hand, the possible applications of gypsum are becoming more and more diversified for example: fire-retardant or water-repellent gypsum plasterboard, plaster, flowing screed and gypsum fibre board are just some of the applications in the construction industry. No industry can do without gypsum anymore. This makes it all the more important for leading manufacturers, such as Knauf, to use limited raw materials sparingly.

The hunger for gypsum

The fibreboard production at Knauf in Rottleberode is supplied with stucco from the gypsum plant via a specially built pipe(line) bridge.

At the Rottleberode plant, for example, Knauf returns the edge breaks which occur during the production of gypsum fibreboard to the material flow in the same way as the dust during surface grinding. “Every crumb of gypsum is important for us. This is why raw materials should no longer be disposed of during production,” emphasises plant manager André Materlik. His company is the only one within the Knauf Group which exclusively processes natural gypsum from the quarries in the southern Harz region. In view of the move away from lignite mining, industry experts argue that only those companies which develop and secure mining areas in the long term will continue to exist – and demand for gypsum in Germany alone is already high at around ten million tonnes per year. According to Materlik, around 450,000 tons of finished product leaves the Rottleberode plant every year, with around 100 truckloads a day.

Stucco plaster, fine cellulose from waste paper and water: this is the mixture from which gypsum fibreboards are made. ISS Schüttguttechnik GmbH from Wilnsdorf in the Siegerland region plans and builds blow moulding machines to supply the mixers. ISS had already done a good job at Knauf before the new fibreboard plant was built, and had successfully got to grips with the problems involved in conveying and metering pulverised lignite. The fuel develops the necessary heat for calcining the rough stones. In the process, the natural gypsum loses a large part of its crystallised water content. “For uniform thermal processes, the constant transport of lignite without pressure or volume fluctuations is essential,” explains the plant manager. Any deviation from the ideal line is noticeable and can affect the product quality of the stucco, the deposits in the calcining mill, the CO values in the exhaust gas flow or the energy consumption of the screw compressors. “Uniform processes require less air,” says ISS Sales Managing Director Robert Partzsch, who speaks from experience.

Process-safe with high efficiency

ISS Schüttguttechnik has planned and realised the new stucco supply together with Knauf Engineering.

For this reason, ISS has also put all of its know-how into the development of an overall solution for the conveying of stucco plaster, which was developed in Rottleberode together with the plant planners of Knauf Engineering GmbH. The company, under the Knauf umbrella, planned the entire new building at Iphofen and also ordered the conveyor technology. The main focus was on process safety, longevity and energy efficiency. „The high efficiency is due to the AERZEN screw compressors,“ says Partzsch. In addition, the Delta Screw series is recommended because of its pressure range, which is ideally suited for the transport of stucco.

It is important to know that according to the experience of the ISS Managing Director in the pneumatic conveying of bulk materials, compressed air with 5 to 6 bar is often first generated in order to feed an air vessel. This makes available an often significantly lower delivery pressure. “Intermediate buffering always results in energy losses,” emphasises Thomas Koch, head of technical mechanics at the Knauf plant in southern Harz. The Joule-Thomson effect is proof of this. Every 100 millibar increase in pressure causes a temperature rise in the compressed air of +10 degrees centigrade, due to the increased friction of the molecules. The effects of this physical connection can be limited if air vessels are dispensed with - as is the case at Knauf. However, since thermal energy cannot be completely prevented during pneumatic conveying, Knauf uses it in winter with recovery for heating purposes.

Never wasting any energy

Delta Screw units of type VM21 supply a volume flow up to 1200 cubic meters per hour.

In view of the fact that it is always better not to use electricity in the first place, rather than returning it later as heat, the goal must be to use compressors in energy-intensive compressed air that deliver the required volume flow with exactly the required pressure without intermediate storage. “AERZEN is simply the leader in the range from 2 to 3.5 bar,“ notes Partzsch and adds: „why should I generate 6 bars when I only need 3 bars?“

The Delta Screw units type VM21 with a motor rating of 90 kW supply a volume flow of 1,200 cubic metres per hour. The maximum pressure is 3.5 bar. The Generation 5 machines of the Delta Screw series installed at Knauf are designed by AERZEN as universal machines - with great attention to efficiency. Developed as a flexible modular system, the different compressor units can be suitably configured with motors of varying performance and an extensive range of accessories. Belt drive adjustment options, for example, provide the basis for accurately adjusting the volume flow even at fixed speeds - with the aim of preventing energy-intensive excess generation. This claim is backed up by the renunciation of redundancy at Knauf. Compressors and conveying systems work so reliably that separate „backup technology“ can be dispensed with. “The plant is designed for a capacity of twelve tons of gypsum per hour,” says Koch. If one assembly is taken off the grid, a temporarily switched bypass solution ensures reliability of supply. “However, our installation generally provides that one compressor always serves one system,” he adds.”


In the course of building Knauf’s new fibreboard factory in the southern Harz, the newly installed blow moulding systems for pneumatic conveyance of stucco highlight some of the most important elements for minimising the consumption of costly energy - the focus was on increased efficiency and optimal design at the point of operation. Knauf has a clear system concept with the equipment at its works. “It is the combination of scientific and technical knowledge which makes up the solution of ISS. Here, everything is as it should be,” says plant manager Materlik.

Compact news

Aerzen USA continues to grow: new office in Atlanta

Following the expansions of the headquarters in Coatesville/Pennsylvania and the opening of a new sales office in Houston/Texas in 2017, Aerzen USA has now opened up in the southeast of the United States: in May 2018, the AERZEN subsidiary inaugurated a new location in Atlanta/Georgia. The new building covers almost 2,000 square metres of production and storage space, as well as an area of 260 square metres for offices. “We are pleased that we are now closer to our customers in the southeast of the USA,” emphasises Tony Morris, Managing Director, Aerzen USA. “The new facilities will allow us to serve important markets more flexibly and efficiently,” he adds.

The space in Atlanta is available for rental machines, spare parts warehouses, assembly, repair and maintenance of assemblies, as well as state-of-the-art test procedures. The new offices are used primarily for sales, and there is space available to accommodate more employees in the future. The site is expected to be fully operational in the autumn of 2018.

AERZEN China at the IE Expo 2018

Aerzen China had a strong presence at the IE Expo 2018, held in Shanghai from 3-5 May, which attracted more than 60,000 visitors from over 60 countries. At Asia‘s leading trade fair for environmental technology, the company presented itself with the motto: Performance3 - The Next Generation.

At the AERZEN booth, prospective customers could gather information about Aerzen Turbo AT300-0.8, Delta Hybrid D62S, D17L and AERsmart by means of sectional models. The team welcomed not only visitors from China, but also customers from Singapore, Malaysia and Thailand. Chuck Lim, Vice President Aerzen Asia Pacific, also participated in the IE Expo. First Environmental Protection Net conducted an interview with Sam Hoo, General Manager Aerzen China, on 3 May about the innovative AERZEN technology, and this was transmitted online.

The conclusion: the three trade fair days were very positive for AERZEN’s brand awareness and have confirmed the position of the company as a leader in the environmental market. Aerzen China is already looking forward to IE Expo 2019.

Determining savings potential online

With a right-sized machine configuration based on highly developed AERZEN technologies, the company offers maximum savings potential for all plant operators in waste water treatment. AERZEN customers can now easily test how efficient the aeration in their blower station really is with the performance calculator on the AERZEN website. All you have to do is enter your current number of machines, the volume flow and the differential pressure, and you will immediately receive an initial result as to the level of potential savings that can be achieved. You will also be shown what your individual machine configuration would look like with the technologies in question in order to achieve the savings potential.

Since each plant has individual requirements, AERZEN provides the customers with a tailored design based on the AERZEN Perfomance³ product portfolio - consisting of positive displacement blowers, turbo blowers and rotary lobe compressors.

Performance Calculator

Visit from IBAR to AERZEN

On 19th April 2018, a delegation from IBAR, the Upper Austrian sewage works operator association visited AERZEN. The guests were duly informed about the product range and visited the company offices. The visit to AERZEN took place following a suggestion from the Managing Director of AERZEN Austria, Martin Barger, who had made a special presentation at an IBAR meeting last winter. Martin Barger was also present at the head office in AERZEN, in order to welcome our guests, together with Markus Leidinger, applications specialist in wastewater technology.

At the start of their visit, Barger presented the history and product range of AERZEN to the sewage works operators. After this, Leidinger engaged with a compelling presentation about the application and combination possibilities of the different blower types. A factory tour was the next item on the programme. Product manager Ricardo Wehrbein and sales engineer Thomas Kuhn led the guests in groups through the company and presented each individual processing step for the blowers. Josef Ortner, Chairman of IBAR, thanked Barger and the management of AERZEN.

Remko Knol, the new CEO of Aerzen Nederland

On July 1st 2018, Remko Knol became the new Chief Executive Officer (CEO) of Aerzen Nederland B.V., based in Dui-ven near Arnhem. He is thus responsible for the business operations and strategy in the Netherlands. “We are very pleased that Remko Knol has joined our management team. He has a lot of process know-how and knows a lot about the development of production processes, as well as the application of AERZEN solutions,” says Siert Wiersema, Deputy Managing Director Aerzen Nederland.

Knol, who studied mechanical engineering and holds a master‘s degree in general management, can look back on 15 years of experience as a sales manager and managing director in the international technology environment. He has worked for Siemens Power Generation and Siemens Water Technologies, among others. For the past six years, Knol had served as Managing Director of Frames Separation Technologies B.V., Netherlands. The company designs and supplies process plants for the separation of oil, gas and water, as well as the treatment of production water.