Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 75
Glass melting (at high temperatures)
Оглавление| M1 | Primary batch‐to‐melt conversion, yielding a rough melt still containing considerable amounts of gas bubbles and undissolved solids Time demand: about one hour Intrinsic energy demand: about 2000 MJ/t of produced glass (3.6 GJ = 1 kWh) Temperature range: 600–1200 °C |
| M2 | Sand dissolution (comprising the dissolution of any other crystalline solids) Temperature range: 1200–1400 °C Intrinsic energy demand (mostly for heating up the melt): approx. 280 MJ/t of glass |
| M3 | Fining, i.e. physical removal of residual bubbles via the thermochemical generation of an adequately high‐volume fraction of large bubbles of a fining gas Temperature range: 1400–1500 °C Intrinsic energy demand (for heating‐up): approx. 140 MJ |
| M4 | Refining, thermal, and chemical homogenization, whereby refining denotes the resorption of residual gas bubbles upon steady cooling Target temperature: 1350 °C Heat released: −220 MJ. |
At the end of step M4, the melt is finally conveyed to the forming area where it is transformed into hollow ware (Chapter 1.5), or flat glass (Chapter 1.4), or any other type of product. To maintain a high glass quality, the filling level of the melting compartment must be kept constant. Therefore, the sequence of process steps P1 to M4 must be well balanced logistically. This constraint puts a stringent time interval to act for online corrections to steps P4–P6; the buffer silo between steps P5 and P6 thus serves the sole purpose of widening this interval. Along the path from P6 to M4, no action for correction is possible at all.
