One of the World´s Most Modern Float Glass Plants in Operation

In Saxony-Anhalt, f l glass GmbH put one of the world´s most modern plants for the production of float glass into operation. Each day 700 tons of plate glass are manufactured, for the solar industry among other things. The technical know-how and the machines come almost exclusively from Germany.

Dr. Arjen Steiner points to a wall on which more than two dozen monitors hang. Here, he explains, "is the heart of the entire facility, so to speak." He is referring to f l glass GmbH´s recently completed float glass plant. At the gates of Magdeburg, in the little village of Osterweddingen, one of the world´s most modern facilities for the production of float glass was erected under the supervision of DTEC Engineering & Consulting GmbH. Founded in 1999 and based in Gelsenkirchen, DTEC and its two subsidiaries, Continental Glass and Engineering GmbH (CGE) and Glasinvest Engineering und Anlagenbau GmbH, specialise in the planning of glass manufacturing and processing plants. As project manager, Dr. Steiner was responsible for the construction of the plate glass plant in Osterweddingen. According to the graduate engineer, "We are capable of placing turnkey facilities for glass production virtually anywhere in the world on a Greenfield site." In Osterweddingen DTEC was responsible for general planning, project management and construction supervision.

Gross Annual Capacity: 255,000 tons
On an area of 42 hectares and in the record time of one year, f l glass GmbH had a float glass plant erected in close vicinity to the provincial capital of Saxony-Anhalt, in which 255,000 gross tons of window and white or solar glass are manufactured annually. "The goal," states production supervisor and graduate engineer Gerd Steger, is a fifty-fifty ratio, although the tendency leans clearly toward white or solar glass. f l glass partners – also active in the glass-manufacturing field – are the Dutch Scheuten Group with 51 percent, and the German-based Interpane Industry AG, who holds the remaining 49 percent of the partnership shares. The total investment amounted to roughly 190 million euros. Included in the price is also a magnetron facility in which the glass can be processed to serve as sun and heat protection glass by applying metal-oxide layers. This plant is intended to go into operation in the first half of this year. The same applies to the production start for single-pane safety glass.

As with most float glass facilities, the scale of the new plant is quite impressive. The production line alone is 800 metres long. The chimney for the melting furnace, in which the batch is melted into glass, juts a proud 84 metres into the sky, and the gargantuan 68,000 square-metre warehouse and shipping hall offers space for 60 days worth of production. Add to this a large silo plant in which the necessary raw materials, including sand, lime and dolomite are stored in 16 enormous steel containers, as well as a several-100-square-metre cullet storage area. According to production chief Steger, approximately 240 people are currently employed.

Turnkey Batch Plant
The equipment for the plant come almost exclusively out of German machine and equipment manufacturers´ production facilities. The batch preparation plant, in which – depending on the type of glass –various raw materials are, for example, weighed and mixed before they are finally melted into glass in the melting furnace, was delivered by the Wertheim-based specialist for batch preparation plants, Zippe Industrieanlagen GmbH. To wit, as the company´s responsible project manager, Heiko Brand, emphasises, "on a turnkey basis." Each of the various raw materials is transported via screw conveyer to one of the eight scales and from there via conveyer belt to one of the two mixers.

True, one mixer would suffice. Should one malfunction sometime, however, the second can immediately be put into operation to prevent a loss of production. For the same reason there are also two conveyer belts from each mixer to the trough pre-silo, from which the batch from four batch chargers (also from Zippe) is pushed into the melting furnace. The trough pre-silo serves to translate the discontinuous batch preparation process into a continuous glass melting process – an important step in glass manufacturing, in which no errors can be tolerated. The cullet system, also made by Zippe, handles the transport and subsequent recycling of the cullet accumulated during glass processing. The cullet thus gained is subsequently reused in the manufacture of new glass.

Furnace Said to Last 20 Years
The heart of the entire plant is the mighty melting furnace, of which graduate engineer Wolfgang Räbiger, technical director at f l glass is especially proud. Räbiger was significantly involved in the conception of the furnace. The paragon, he explains, was a furnace he was also involved in and that was in operation for 16 years without a problem. The new one, he is confident, will last at least 20 years. Conceptually it is a dual-chamber side-fired regenerative furnace. The necessary heat – up to 1,600 degrees Celsius – is delivered by six natural gas-burning burner pairs. The capacity of the 66-metre long and 12.5-metre wide furnace amounts to approximately 2,200 tons, which corresponds to roughly three days´ production. It took close to three weeks for it to reach operating temperature during the start-up phase.

Two Roller Drive Units
After the batch has been melted to liquid glass in the melting furnace, it swims in the form of an endless ribbon on a bed of liquid tin into the annealing lehr, where it is slowly cooled to reduce stress in the glass to a minimum. The drive system that ensures that the 289 rollers always move the glass ribbon steadily and precisely in the right speed through the lehr was delivered by Z&J Technologies GmbH in Düren. A second drive unit that can quickly take over in an emergency ensures a high level of production security. Also from the company in Düren are the six rerouting systems for flue gas and combustion air, with which, as explained by Eberhard Ruhland, division director for the glass industry product line at Z&J Technologies, the firing process in the melting furnace can be controlled. The company also delivered the furnace pressure control cap for the melting furnace; it sits in the main channel and ensures that the pressure remains within tolerances.

Optimisation System Installed
From the lehr, the glass ribbon is transported into the so-called "cold end", which was – with the exception of the inspection system for automatic flaw detection – delivered by Grenzebach Maschinenbau GmbH, part of the Grenzebach Group. Roller conveyors move the glass ribbon through the various workstations, where it is inspected for flaws and subsequently cut and broken according to the delivered data. In order to ensure the best possible cut quality, the borders are broken on the inside and outside. A further inspection follows, during which the geometry of the panes is controlled and the panes precisely measured. At the end of the line, the finished panes are then stacked, either tin side or atmosphere side out depending on the customer´s specifications. This entire process takes place fully automatically. The optimisation system for our plant, states Egbert Wenninger, member of the management at Grenzebach, "ensures that the cull is reduced to an absolute minimum and the entire plant runs optimally according to the respective requirements – all the way to the stackers."