Edition 03/2018

It says NaCl in big red letters in the front of the building: Sodium Chloride - and the building contains what it advertises. 4,500 tons are stored here at peak times. The salt that is waiting to be put to use in Bertrange, a town to the west of the city of Luxembourg, is responsible for keeping the 3,960,000 mÇ of highways of the Grand Duchy of Luxembourg free of ice and snow during the cold season. “To make the salt adhere better to the roads, and to achieve the optimal thawing effect, we use a self-produced salt solution containing 22% salt,” says Pierre Servais from the road construction administration of Luxembourg (Administration des ponts et chaussées), which is responsible for the construction and maintenance of public roads. The salt solution is produced directly at the salt depot in Bertrange from rock salt with a purity of at least 98 percent. Because without salt, winter service would not be possible. So every year, before the cold snap begins, the depot is restocked in good time. The precious commodity is delivered by trucks and is unloaded in front of the depot. But how do all of these millions of salt grains get into the 20 metre tall salt silos? For about a year, this has been made possible by a positive displacement blower GM 35S (max. 2,418mÑ/h, 1 bar differential pressure) produced by AERZEN, which is part of the globally successful Delta Blower series. Numerous processes are powered by the versatile compact assemblies. Especially for pneumatic transportation of bulk material - like the salt in Luxembourg for example - the belt driven blowers with rotors are first choice. These work highly efficiently, are oil-free as per class 0, and thanks to patented discharge silencers without any absorption material, are also ATEX certified.

When the old salt conveyor system in Luxembourg failed, immediate support was of the essence. “In winter service we just cannot afford the failure of one of our facilities,” says technical manager Servais. AERZEN helped on the spot and delivered a rental package within 24 hours. “We were convinced by the immediate service and the great performance of the machine.” Because of this, the contract to replace the faulty system was also placed with the Lower Saxony machine manufacturer. Christoph Winter, sales engineer at AERZEN explains: “The old machines were located inside the warehouse where the salt was stored. So it was immediately obvious to us that the system had to be moved out of the salty atmosphere. The reason being that salt is highly corrosive and puts a lot of stress on the equipment. This results in premature corrosion and a short lifespan.” Plenty of space was available for permanent installation of the blower equipment in front of the warehouse, but it turned out that any changes to the appearance of the building were not allowed. The reason for this was that the building was designed by the Luxembourg firm Bruck + Weckerle and its transparent Prokulit light panels have been awarded multiple times: in 2007 the design won the ‘Luxembourg architecture award’ (Prix Luxembourgeois d’Architecture), followed, in 2008, by the ‘Bauhärepräis.’ The solution: the AERZEN blower was mounted on a heavy-duty trailer so that it can be moved and connected to the plant as and when required. In order that the appearance of the warehouse is not impaired the assembly can be stored away in summer. In winter it is set up by the use of a fork lift truck. As soon as the trucks unload the salt, it is picked up by wheel loader and dropped into a funnel. It then passes through a rotary valve distributor, which takes care of the right dosage and a constant throughput, and ends up in the product inlet. From there, it is transported with a pressure of 0.4 to 0.5 bar (maximum of 0.63 bar) and a flow rate of 1,920 mÑ/h in pipe sytems up to lofty heights by AERZEN technology. In total, two silos with a holding capacity of 250 tons each have to be filled.

For the construction of the trailer, as well as the piping, Emde Automation GmbH from Nassau, a company that AERZEN  has worked with for more than ten years, was brought on board. “We recalculated and reinterpreted the product-to-air-ratio inside the pipes and flow-optimised the product inlet,” explains Björn Redert, project manager in the sales department at Emde. “The challenge was to recycle and integrate existing components of the old facility made by our competitor into the new concept.” On top of this, Emde applied protection against wear in some parts of the piping system. This became necessary as the walls of some of the pipes had become thinner due to the friction caused by the salt transportation process. “The cooperation with AERZEN has again been a great pleasure,” says Redert. “It just works - from preparation of quotations to the support and the service. And the quality is also spot-on.” Pierre Servais is also completely satisfied: “It was the right decision to put the blower outside. The system performs significantly better now.” To the Luxembourger, one aspect is particularly important:  reliability. “We need a plant that we can depend on. Because in winter we need to be ready for operation at all times. In AERZEN we have found a reliable partner that provides us with products that are long-lasting and which require little maintenance, as well as competent consulting and comprehensive customer service.” It is beyond all question that this successful cooperation will continue. The first follow-up project is already a done deal. Because just a few weeks ago the second conveyor system for salt in Bertrange also failed. Competitor products were also used here. The details have already been discussed, soon another AERZEN blower will be delivered to Luxembourg.