Siemens technology plays a decisive role in the plant’s success.
After successfully beginning production in the fall of 2009, f | glass GmbH in Osterweddingen, Germany, now produces up to 700 tons of float glass a day. The stockholders of f | glass are the Dutch glass industry specialist Scheuten Group and Germany’s Interpane Industrie AG. The joint venture’s float-glass plant sets industry standards in several ways: not only does it lead the way in terms of process and plant technology, the production plant also stands out for product quality and construction time. It took only 15 months from groundbreaking to the start of production.
Optimum conditions – that was the motto from the very start of the project, according to Herbert Köhler, CEO of f | glass GmbH. “The decision to build in Osterweddingen itself was a real milestone. There were a number of sites with similar infrastructure, but Osterweddingen offered the best total package overall: ideal connections to the gas and electricity supply, good links to the traffic network, and good raw material supply. In addition to the optimum site, such a project also requires clear goals. We therefore set a fixed deadline for the start of production. And this was to be achieved within the set budget. We achieved both. We are very proud of this, especially in view of the complexity of the project.”
Dr. Ing. Wolfgang Räbiger, chief technology officer at f | glass, adds: “Within a very short period of time we built a fully integrated solar-glass production unit that allows a relatively new product – a very low-iron glass designed specifically for the solar industry – to be manufactured at one site: from the float-glass unit to the cutting lines and the coating of large-format glass sheets all the way to our solar-glass center where we give the glass specific properties that are important for the solar industry. Here especially, we have conquered new territory in machine technology.”
Innovative technology “Made in Germany”
There is a technological highlight right at the beginning of the process: the glass furnace, a regenerative cross-fired furnace with six pairs of gas-fired burners. Räbiger continues: “Our goal was to build a furnace that is able to do just about anything. It was supposed to be able to melt normal glass, white glass for construction, and solar glass, but also consume as little energy as possible and have a long service life – altogether a real challenge for the furnace design.” The previous furnace, also co-developed by Räbiger, was in operation for 16 years. “We clearly want to do better than this. I am certain that the new furnace will be in service for 20 years,” he predicts.
Not only the furnace is based on German know-how; nearly all the other equipment for the plant was supplied by German machine and plant equipment manufacturers. For Dr. Thomas Belgardt, managing director of glass processing at f | glass, supplier quality is decisive: “In this regard, it is not just about the technology being delivered but also about a long-term partnership. After all, in 10 to 15 years we still want to be able to rely on competent support. That is why we always select market-leading suppliers.”
State-of-the-art energy recovery
Osterweddingen is one of the first glass plants in the world to recover a large part of the process waste heat using a modern heat-recovery system. The system’s most important component is a compact Siemens industrial steam turbine with a rated capacity of 2.5 MW, which f | glass uses to generate electrical power from the waste heat in the process exhaust air. The energy-recovery system not only saves energy, but, according to Räbiger, “the energy-recovery process also helps ensure process security. By producing 60 percent of the electricity required for the float-glass plant ourselves, we are better able to cope with a power outage, for example. The turbine is also a very important technological installation in this respect.”
Reliable control technology
The control technology system in Osterweddingen, which is based on the most recent version of Simatic PCS 7, was implemented by the Siemens Industry Partner STG. The system is operated via five Simatic WinCC clients, an engineering station, and a web server. The operating level is connected to the two redundant control system servers via Industrial Ethernet. The system bus is also based on Industrial Ethernet. The furnace, float bath, and annealing lehrs are each controlled by a dedicated PCS 7 AS 416 automation system. Visualization of the top rollers as well as the electrical and control technology systems is also integrated within PCS 7. Reversal switching is redundant and is controlled by the furnace automation system and a lower-level Simatic ET 200M of the automation system in the float bath. “We are very satisfied with the technology being used,” says Räbiger. “The constructive and committed approach demonstrated by the Siemens specialists as they supported us in solving problems was excellent, as was the professional and successful implementation of the project.”
Since officially starting production in the fall of 2009, the plant has been working perfectly apart from a few minor hitches, as was to be expected with a greenfield project of this nature. Gross output at f | glass is currently 255,000 t of float glass per year. At the beginning of 2010, the Magnetron coating line began production and is coating around 6 million m2 of glass a year – or more upon request. Around 80 percent of the production output is shipped to the building construction sector; however, in the next five years the share of ultrawhite glass and solar glass is to be increased to approximately 50 percent. Thanks to its high-performance production technology, Osterweddingen is optimally equipped for the job.
Highly transparent solar glass boosts solar yield
One product of the f | glass Osterweddingen plant is f | solarfloat HT, a special highly transparent solar glass. The glass, which features an innovative antireflective coating, achieves unsurpassed values for energy input into the solar module and thereby increases the solar yield. The antireflective coating increases the share of sunlight used for power generation, even in the case of an unfavorable, flat angle of incidence. The coating is made of extremely resistant quartz glass – this protects from harmful environmental influences. The narrow manufacturing tolerances as well as the comparatively flawless surface of the float and solar float glass guarantee reproducible high edge quality as well as superior glass strength. The characteristic bending tensile strength of the 3.2 mm thin tempered glass by f | solar far surpasses the standard requirements for conventional 4.0 mm thick tempered glass. The reduced weight saves costs and offers logistical advantages: per truckload, it frees more than 4,000 kg of cargo capacity. Ultimately, the thinner glass also helps reduce the weight of the finished solar module.