Causes and Countermeasures of several bubbles in t

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Causes and Countermeasures of several bubbles in float glass

bubbles will appear in the production process of float glass for different reasons. The following briefly introduces the causes and Countermeasures of several bubbles

clarifying bubbles

(1) the appearance bubbles are evenly distributed on the surface of the glass plate, and the bubble diameter ranges from 0.1mm to 1.0mm. The small bubbles are round, and the large bubbles are oval, which are mostly distributed in the glass plate

(2) there are no condensates on the bubble wall. According to the bubble composition analysis, there are many N2 and CO2 gases in the bubble

(3) causes

a. if the addition of clarifier has insufficient requirements for elongation, it will cause poor clarification

b. the hot spot atmosphere is partial oxidation, which makes SO3 unable to be discharged and cannot give full play to the role of clarifier

c. insufficient thermal barrier (glass liquid flow barrier formed by hot spots)

d. the last pair of small furnaces of the furnace operate in a strong reducing atmosphere

e. poor melting causes the bubble boundary to move backward and the clarification area is too short

f. the melting temperature is too low

(4) take measures

a. adjust the mirabilite content according to the residual amount of SO3 in the finished glass and the product quality to ensure that the finished glass contains 0.19 ~ 0.25% SO3

b. adjust the hot spot furnace atmosphere to be neutral to reductive

c. strengthen the thermal barrier

d. adjust the flame atmosphere of the last pair of small furnaces to be at least oxidizing and neutral

e. adjust the position of bubble boundary to ensure the length of clarification zone

f. maintain a suitable melting temperature

over reducing bubble

over oxidizing bubble (a kind of mirabilite bubble)

bubbles formed by refractory

(1) due to the complex position of appearance, there is no regularity in size, shape and position in the glass plate. Generally speaking, in the rear area, due to the reducing substances in the refractory, the bubble diameter is large, and the bubble size formed by the gas discharged from the apparent pores of the refractory is different

(2) if the microstructure is a bubble formed by carbon in the refractory, the bubble wall has a slight trace of sulfur precipitation. If the bubble is formed by the discharge of the refractory hole, the gas composition in the bubble is close to the air

(3) causes

a. due to different production methods, some refractory materials will introduce some carbon. After contacting with the liquid glass, these carbon will form CO2 bubbles with oxygen dissolved in the glass or react with SO3 dissolved in the liquid glass to form SO2 precipitation and bubbles

b. refractory materials will contain certain porosity during processing. During the erosion of molten glass, the gas wrapped in the hole will penetrate into the molten glass and form bubbles

(4) take measures

a. select high-quality refractory materials to reduce the porosity of the liquid glass in direct contact with the liquid glass

b. the second thing to reduce the refractory materials in contact with glass is the carbon content of the door sill in the tender

c. reduce the reaction temperature and prevent the chemical reaction between glass and refractory

stirring bubble

(1) the appearance bubble diameter is large, generally more than 1.0mm, located on the upper surface of the glass plate, with ripples, and the bubble position is fixed

(2) under the microscope, there are vacuoles, and the gas composition in the bubble is close to the air composition

(3) causes:

a. the liquid level of the mixing rod into the glass is too shallow, and the air is wrapped into the liquid glass

b. the rotating speed of the mixing rod is too fast, so that the air is wrapped in the liquid glass

(4) take measures:

a. adjust the depth of the mixing rod into the liquid glass

b. reduce the stirring speed without affecting the surface quality (optical deformation)

bubbles formed by solid or liquid inclusions

some solid and liquid inclusions can directly enter the glass melt, such as bubbles generated by substances such as dust, condensate, soot, oil droplets and so on. When slightly vibrated,

bubbles formed by solid and liquid inclusions can be divided into two categories

① reducing substances are oxidized by the melt

② substances with high vapor pressure or decomposition pressure at the temperature of the melt. Under the economic internal circulation of China glass () department, in April 2021, China Chengdu Jianbo Jinmin lightweight material washing machine inner cylinder will talk with you about new opportunities in the industry

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