Application of infrared thermometer in the glass industry
In the production process of the glass industry, temperature measurement and control is one of the very important and necessary means. Infrared temperature measurement has the characteristics of simple operation, fast response, no aging, small drift, flexible configuration, and will not contaminate the glass. Solution and other factors are taken seriously.
In the glass industry, the temperature of transparent and opaque objects needs to be measured. Opaque objects include molds, domes, and sides of glass melting furnaces. As the measured object for non-contact temperature measurement, glass is a transparent visible object, and its spectrum is within the near-infrared spectrum range. Its emissivity is related to the wavelength and the thickness of the glass. When the spectral range is between 5 and 8 μm, its emissivity is the highest, so the temperature of the glass can be measured reliably in this range. The measured value is consistent with the surface temperature of the glass, regardless of the thickness of the glass. Within this range, there is basically no radiation. In order to avoid the measurement being affected by the surrounding air, the thermometer only uses a very narrow infrared spectral band. High-quality thermometers only work in the spectral range of this so-called environmental window, because there is no absorption of infrared rays due to air humidity or carbon oxides. This avoids measurement errors due to changes in air humidity or measurement distance. temperature error. Narrowband range 5 (approximately 5 μm) is used to measure surface temperature.
Infrared thermometers generally work in the 5.14μm spectral range, because the hot exhaust gas from the burning burner in this area will not affect the measurement value. For other areas of application, it is necessary to measure the temperature inside the glass, since the glass layer close to the surface is greatly affected by convection currents. What needs to be measured here is the molten glass, so a thermometer in the near-infrared range needs to be used. Since the penetration depth achieved at different wavelengths is also different, the choice of thermometer depends on the thickness of the glass layer. Non-contact temperature measurement technology in glass furnaces, tin baths and annealing kilns is increasingly replacing traditional thermocouple temperature measurement in glass furnaces.
Compared with thermometers, thermocouples will age and drift quickly under high operating temperatures and corrosive environmental conditions. In order to protect thermocouples, platinum metal is required to be used as a protective shell in some places, which will increase the cost a lot. . Specially designed for this field, it does not require a cooling system to work even when the ambient temperature reaches 250°C. By using fiber optic pyrometers, installation and operating costs can be significantly reduced. The fiber optics can be protected by a solid stainless steel housing and can be up to 30 meters. Required installation accessories such as mounting brackets, air cleaners, and peek tubes (can be used up to 1200°C).
