A shift in mindset has finally begun in the glass industry and focus is now moving towards a carbon free future - several hybrid and all-electric melting initiatives are becoming a reality. The need for larger installed power supplies brings new design challenges as well as interesting opportunities. Choosing a power supply provider with a high level of expertise is key to achieving the most energy efficient and cost effective solution, says René Meuleman.
As a power supply system provider, Eurotherm by Schneider Electric obviously had to anticipate this shift in developments ahead of time and fortunately it was not rocket science to predict these advancements. Knowing that each tonne of glass produced would need approximately 2.8GJ – 3.0GJ of electrical energy, it was not difficult to calculate that a new generation hybrid or all-electric furnace would need around 10 to 12MW of installed power, to achieve an average pull rate. That’s nearly five times the amount of electrical power installed for a typical furnace boosting system on today’s regenerative end-port furnaces!
Even though traditional 1.5 – 2MW furnace boosting power supply systems need to be carefully designed, 10MW systems will bring entirely different design challenges. To start with, it is likely that the traditional method of firing the electrodes against each other will need to be reconsidered and discontinued. Long cables or busbars will need to be avoided to prevent unacceptable magnetic induction impacting the power system’s efficiency and perhaps also personal safety. The supply current will also need to be kept as low as possible to reduce the need for expensive high current switch gear, transformers and thicker cables or busbars.
New furnace designs will unavoidably need modelling studies carried out, resulting in glass resistivity assumptions which, in turn will impact transformer design and cost. Mistakes in transformer specification and design are difficult to correct and over-engineering systems, to limit design risks, is both expensive and contrary to the goal of reducing environmental impact. The world’s furnace builders and designers should be aware of the flexibility that modern power control systems are capable of providing. Because, with or without the help of the few companies providing furnace modelling expertise, this flexibility will help them find the most cost and energy efficient electrode positioning for the process.
Furnace and electrical power supply designs are mainly based on physics and there are lots of parameters that affect each other. Furnace builders are well respected for their furnace design capabilities, but power solution providers such as Eurotherm by Schneider Electric should be considered the power supply experts, having decades of history in specifying, designing, engineering and installing SCR controlled systems, along with the associated products and components. As the industry steps up to +10MW of installed electrical power, technical knowhow is imperative whether for an all-electric or hybrid furnace design. Therefore, furnace building and power supply expertise should now be combined together to achieve efficient glass manufacturing melting systems. Each party can provide their knowledge and IP which will minimise the risk of failure of the whole furnace design. The way the energy is deployed from the grid to the electrodes is crucial. Therefore, the efficiency of the complete system, grid stability, personal safety and availability of the furnace are highly dependent on the selected power control system. Common sense dictates that this kind of knowledge can only come from an experienced power solution provider.
Installation of +10MW power supplies will also change the way utilities can be managed. Microgrid and smart grid power supply capabilities will put glass manufacturers’ energy purchasing departments in a much better position to negotiate energy contracts. For example, by utilising the freedom of electrical power control to help stabilize increasingly unstable electrical grids and getting lower energy tariffs in return. With a +10MW installed supply, it makes absolute sense to combine glass manufacturers’, furnace builders’, power supply providers’ and energy utilities’ business cases to find win-win situations through collaboration: taking advantage of the best of multiple worlds with each party contributing their skillset. The bottom line is that with increasing power demand, both size and expertise matter!
Special thanks to former Business Leader for Global Glass at Eurotherm, René Meuleman, for authoring the original content of this article.
The full version of this article appears in the May/June 2020 issue of Glass Worldwide alongside a broad cross-selection of editorial that assists with all areas of production and processing.
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