Glass production can be traced back to before the Roman civilization. The Latin term “glesum” can be roughly translated as “transparent lustrous substance”. Flat glass has changed very little since its inception as blown cylinders flattened out and the majority of today’s flat glass (about 90%) is produced using the float glass (Pilkington) process that was developed in the 1950s in England.
The global flat glass market was estimated to be over $30 billion in 2012, driven largely by demands of construction and automotive glass sectors. Current demand by China, North America, and Europe account for over 70% of products delivered. Future demand is expected to increase steadily as emerging markets develop.
To sustain these demands, there are over 200 float glass production plants worldwide. They produce over 60 million tons (about 7.5 billion square meters) of glass annually! But float glass production can be expensive due to the high cost of transportation and energy required for glass melting (often up to 1700 °C). In order to reduce costs, these plants tend to be regionally distributed to minimize the high costs of transportation and tend to operate continuously to minimize losses.
Energy consumption represents approximately 21% of the total cost of float glass production. The high temperature processes of glass melting and forming account for about 80% of the energy usage. Accurate and precise temperature measurement is critical for efficient and cost effective melting, glass quality control, heat zone adjustment, and stress reduction. Monitoring the temperature is also directly related to prolonging the life of critical assets such as refractory walls.
For non-contact infrared temperature measurement systems, fully understanding the importance of various parameters is critical to select the correct instruments. These parameters include transmission (τ), reflection (ρ) emissivity (ε) (or absorption (α)). For instance, a pyrometer or thermal imager with a detector that is sensitive at 1 µm can be used to look through thin glass and measure wall temperatures as the glass emissivity is small, and transmission is large. For thinner glass, selecting detectors that are sensitive in the 5-8 µm range will ensure very high emissivity and provide accurate measurements on the surface of the plate. A 3.9 µm detector can be used to measure the temperature a few centimeters down into the glass.
System solutions involving non-contact thermal imaging and pyrometry can help increase production efficiency, reduce waste, and save money in the regenerator, melting tank, tin bath, and lehr. Keep in mind that a 1% efficiency gain can result in significant savings – over $1 Million annually for an average float glass production facility!
What solutions have you implemented to save on energy consumption costs?
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