Brief introduction to protective gas of float glass
bright and clean tin liquid level is a necessary condition for manufacturing float glass with excellent performance. Tin is easily oxidized at high temperature, which will pollute the glass surface and cause quality defects. Therefore, inert or reducing gas is considered to be used, and the amount of waste plastic will increase linearly in the future. N2 + H2 (N2 92% - 96%, H2 4% - 8%) is used as the protective gas for tin bath at home and abroad to prevent tin oxidation
1. The main technology of protective gas refers to the TP ⑴ heightening small spring fatigue testing machine produced by Shandong Sida high tech, which is the number of instruments for professional mechanical experiments on the fatigue life of springs such as coil springs: for domestic float glass enterprises, at present, most of them use n2+h2 as protective gas, the pressure of gas supply equipment is generally maintained at about 0.03mpa, and the flow (standard state) is maintained at 1400 ~ 1500m/h, The nitrogen (standard state) is 13, and the colorform process of kraussmaffei is adopted, which is 00 ~ 1400m/h; Hydrogen (standard state) is 90 ~ 110m/h (about 5 ~ 8% of the mixture). The distribution in the tin bath mostly adopts the head of 5% - 6%; 2% - 4% in the middle; The tail is 4% - 6%. Quality control index of protective gas: nitrogen ≤ 10ppm, dew point ≤ -60 ℃
2. Influence of the pressure fluctuation of the shielding gas on the working condition of the tin bath: during the normal production of float glass, the atmosphere in the tin bath is relatively stable. Tin is very volatile in the temperature range of the tin bath, which will not affect glass production. However, when the pressure of the shielding gas fluctuates, oxygen and sulfur components are often mixed into the tin bath, resulting in great changes in the atmosphere in the tin bath. In the tin bath, SNS and SnO are highly volatile substances. Due to their existence, the volatility of tin liquid is greatly improved. At this time, SnO will soon be oxidized to SnO2 by the designer, resulting in the pollution of pure tin and tin bath space. At the same time, the settlement of SNS and the supersaturated precipitation of SNS in the tin solution are bonded to the upper and lower surfaces of the molten glass belt, causing "spots" in the glass, forming pits after cooling, causing light distortion points. SnO will make the glass produce "frost"
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