Treatment of difficult clarification in the produc

2022-09-27
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In the production of float glass, the treatment method when it is difficult to clarify

the main problem in the production of ultra white float glass is the clarification of glass liquid. Ultra white glass has low iron content and high thermal conductivity, which is 3 ~ 4 times that of ordinary glass, which brings great difficulties to the melting of ultra white float glass. It is difficult to clarify the glass liquid and it is difficult to discharge bubbles: ① due to the low iron content, ultra white float glass has good heat permeability, high temperature of glass liquid, low viscosity, high convection intensity in the horizontal direction, and short residence time of annular flow in the clarification area. ② Due to the low iron content, the vertical temperature gradient in the whole pool depth is significantly smaller than that of ordinary float glass, the temperature at the bottom of the pool is about 6% higher than that of ordinary float glass, the temperature difference between the upper and lower parts of the liquid glass is relatively small, the convection is reduced, and the bubble discharge is more difficult than that of ordinary float glass. ③ The temperature of the reflux liquid glass under the annular flow is not important in the process of moving forward, but to compare the quality of the product and the accuracy of the product, so that the microbubbles that have been absorbed by the liquid glass are released into the liquid glass again under the action of thermochemistry. At the same time, the viscosity of the low iron liquid glass is low, and the microbubbles are very easy to rise into the surface flow, resulting in the obvious rise of bubbles in the liquid glass. ④ In the total oxygen furnace burning natural gas, the content of water vapor is relatively large, accounting for 1/3 ~ 2/3 of the gas composition in the flame space, and the content is the highest at the hot spot of the glass surface, reaching 1/2. With the increase of moisture content, the glass liquid is difficult to clarify, and there are many microbubbles

II. Solutions

(1) adjust the heat load

reduce the heat load of the melting circuit of PE under the condition of insufficient rigidity and heat resistance. Take 6 pairs of small furnaces as an example, reduce the heat load of 1 # ~ 3 # small furnaces, increase the heat load of 4 # ~ 5 # small furnaces, and slightly increase the heat load of 6 # small furnaces, so as to meet the requirements of ultra white float glass. The super white float glass liquid has good heat permeability, which makes the batch easier to melt. Therefore, the heat load of the melting circuit is reduced. However, it is difficult to clarify. In particular, the micro gas industry that it serves in the future can also be extended to military, aerospace and other fields. The bubble is not easy to absorb, which makes the heat load of the clarification circuit increase correspondingly, but the increase of the end to the small furnace should not be too high, otherwise the micro bubbles that have been absorbed by the glass under the forming flow are easy to rise to the surface flow to form secondary bubbles

(2) adopt auxiliary measures

pool bottom bubbling technology can be adopted. The market is in short supply. Add compound clarifiers in the batch, add defoaming agents, etc., and also combine with other advanced melting clarification technologies to reduce the number of bubbles in the liquid glass

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