Talking about the Technological Characteristics of Three Different Transmittances of Float Glass

As we all know, ordinary white glass is mainly used in the field of construction, but also the main product of many float lines, its product characteristics for the glass transmission rate of 67% to 89% (its value with the glass thickness changes) It is a high-quality, multi-functional high-grade new glass, the transmission rate is generally more than 91.5%, while the ultra-transparent glass is a high-quality glass, Iron content is generally controlled below 150ppm; the high white glass mentioned in this article is a kind of between the white and ultra-white glass varieties, the transmission rate is generally controlled between 89.5% ~ 91.5%, iron content control at 200 ~ 400ppm, and its use is to be processed into handicrafts glass to meet the requirements of the market decoration.

 1, three different transmittance glass process characteristics

In this case,The process control of different transmittance glass varieties is determined by its process characteristics. The following are the contrast (%) of the white glass, high white glass and ultra-clear float glass:In this case,The difference between the three types of glasses with different transmittance is the difference of the content of Fe2O3, and the difference is big. The content of Fe2O3 in the clear float glass is about 8 times that of the ultra-clear float glass, and the high clear float glass is 2 to 3 times . Therefore, in the three different transmittance glass species switch to each other, mainly taking into account the changes in the content of Fe2O3 affect the glass through the heat, different glass permeability will affect the glass melting process of heat transfer, the whole furnace The temperature gradient and the vertical gradient of the molten glass change, which will affect the reflux of the molten glass in the whole pool furnace, which will affect the glass quality. Therefore, the switch from the white glass to high white glass, high white glass from the switch to ultra-white glass, according to the different glass permeability through the development of appropriate process systems and process control process, and in the course of the amendment to be melted Quality comparison of the glass to meet the needs of users.

2, three different transmittance glass process control

In this case,In the actual production process, from the low transmittance of the glass species to the higher glass transition rate of the species switch, the glass will gradually increase the heat permeability; according to the foregoing, high clear glass, ultra-white glass thermal conductivity The rate will be higher, the glass liquid in the vertical direction of the furnace heat transfer faster, so the bottom of the temperature will rise. However, due to high white glass, ultra-white glass has a high transmittance, the melting furnace glass liquid radiation coefficient will reduce, which determines the fuel combustion heat released by the glass liquid heat absorption will be reduced to a certain extent, The heat radiated to the body of the furnace and the heat taken away with the flue gas will increase, resulting in the higher heat permeability of the glass, the more difficult the melting, the higher the energy consumption per unit of glass; The higher the glass through the heat better, the production will appear at the bottom of the glass at high temperature, resulting in a higher average temperature of the glass, but the surface temperature of the lower glass, glass liquid in the horizontal direction of convection Strength increases, molding circulation in the clear zone residence time is short, most likely there will be clarification of poor glass. At the same time for the three different transmittance of the glass, the depth of the vertical depth of the vertical direction of the temperature gradient and viscosity of the order of the general white glass, high white glass, ultra-white glass, glass temperature difference between the upper and lower convection The corresponding weakening, the difficulty of bubble discharge will have a greater degree of difference. Because the temperature gradient is large, the discharge of bubbles is the easiest. Due to the heat permeability, the temperature gradient is small and the bubble discharge is more difficult. The bubble discharge of the high-white glass In the white and white high white glass, so high white glass, ultra-white glass production is the first to solve the problem of clarification.In this case,Therefore, in the actual production process, the above three different transmittance glass between the switch, the process characteristics according to their needs to develop appropriate process control system, in order to improve the quality of the glass, The following is the process from the production of white products to switch to high white products or ultra-white products, process control process: (1) broken glass: the current float in the production of general white glass production rate is generally high, so back Glass is less, the general glass production line of white glass maintained at about 10%, but in the high white glass, ultra-white glass switch, due to differences in heat absorption and clarification, in order to produce high-quality glass, so To raise the broken glass to a certain extent, broken glass generally increased to 20 to 30%, is conducive to enhancing the molten glass melting and clarification process. (2) adjustment of the melting process heat load: the production of high white, ultra-clear glass is mainly to solve the problem of clarification of the glass, it is necessary to reduce 1 #, 2 #, 3 # small heat load, increase clarification loop 4 # 5 #, 6 # small furnace heat load, but at the end of the small heat load of the furnace do not increase too much, otherwise the bottom of the flow of molten glass has been liquid glass absorption of micro-bubbles easily rise to the surface flow to the second Bubbles, but also likely to exacerbate the erosion of the bottom of the refractory material, resulting in precipitation of refractory foam. (3) Furnace-related auxiliary equipment adjustment: First, from the white product to high white, ultra-white product switching, the need to increase the deep Jiaobo pressure deep into the liquid glass, glass clarification to enhance the hot liquid Second, try not to use the Kabo stirrer, can effectively prevent the secondary bubble generation probability; Third, the appropriate adjustment of the bubbler to enhance the melting furnace, to enhance the temperature of the bubble, The convection of the molten glass in the vertical direction of the cell furnace accelerates the discharge of bubbles. (4) optimization of the furnace process: First, the small furnace flame optimization, including the flame of the rigidity, angle, etc .; Second, Glauber's salt content, the proportion of carbon powder with the adjustment; Third, the furnace redox atmosphere Adjust the glass; Fourth, the thermal expansion coefficient of glass to adapt to the adjustment; Fifth, material layer thickness adjustment.

3, three different varieties of glass transmission rate of production switching cases

In this case,According to the needs of the market situation, a certain ultra-white float line needs to produce white, white and ultra-white varieties of transparent glass in a certain period. The following is to change the material from white glass to high white glass. clear glass furnace process changes:In this case,From the general white material is gradually switching to high white material, and finally switched to ultra-white material, the bottom temperature increased by 30 ~ 50 ℃, which is due to the existence of the difference between the three glass permeability and the formation of; With the glass through Different heat, targeted to the small furnace heat load was adjusted, the purpose is to improve the clarity of glass liquid capacity to reduce the probability of occurrence of bubbles. It can be seen from Figure 1, the production of high transmittance glass species, the number of micro-bubbles per unit area showed an upward trend, this is because the upper and lower temperature difference of glass is relatively small, the bubble discharge than ordinary float glass As difficult. As the temperature of the molten glass below the forming flow is increasing, the microbubbles absorbed by the molten glass are re-released into the molten glass under the action of thermochemistry, and the viscosity of the low-iron glass liquid is low , The micro-bubbles can easily rise to the surface flow, thereby forming bubbles. Therefore, to improve the production of high-white, ultra-white glass quality, it must be based on its process characteristics, to develop a reasonable process control parameters.In this case,White, high white, ultra-white three different transmittance glass production, the higher the transmittance of the molten glass in the horizontal direction of the convection the greater the vertical direction, the temperature gradient, the smaller the viscosity, and Ordinary float glass production compared to the melting circuit of the heat load should be appropriately reduced, and clarify the loop of the heat load should be appropriately increased, but at the end of the small furnace can not be too high, and to ensure its strong oxidizing atmosphere, so as to Effective control of the probability of air bubbles to produce high-quality glass to meet the high-end building products.