The bottom bubbling technology is to set up one or two rows of bubbling points at the bottom of the tank between the melting zone and the clarification zone of the glass melting furnace, thereby blowing a certain pressure of gas into the kiln without destroying the normal convection of the glass liquid. In this case, the rising movement of the bubbles drives the movement of the surrounding glass liquid, thus promoting the clarification and homogenization of the glass liquid.
Advantages of bubbling technology
After bubbling, a bottom-up annular liquid flow is added near the hot spot of the glass melting furnace, which strengthens the heat convection formed by the hot spot and can effectively block the unmelted scum from flowing to the clarification zone. . The rise of bubbles drives the surrounding glass liquid to move, promoting the elimination of bubbles in the glass liquid. The bubbling stirring effect increases the temperature of the glass liquid at the bottom of the pool, strengthens the heat exchange between the glass liquids, can significantly improve the chemical uniformity and thermal uniformity of the glass liquid, improve the uniformity of the glass products, and make the product bubbles Defects such as , stones and streaks are greatly reduced. Bubbles can also increase the output and save energy. It is better to use bubbling technology in the production of various glass products, especially in the melting process of colored glass with poor heat transmittance such as brown and green.
Technical parameters of bubbling
Although the bubbling at the bottom of the pool has many advantages, if it is improperly designed or operated, it may be counterproductive and increase defects such as bubbles in the glass. Therefore, it is very important to reasonably design the bubbling device and control the bubbling parameters.
① The position, number, distance and arrangement of bubbling points
The more suitable bubbling position is at the hot spot in the kiln or a little behind the hot spot, so that the reflux of the glass liquid formed in this way basically coincides with the reflux formed by the hot spot, and the material blocking and stirring effects are better played. Otherwise, the flow field of the glass liquid in the kiln will be destroyed, and bubbles and stones will be easily generated.
The number of bubbling points is related to the size of the bubble diameter, the distance between the bubbling points, the width of the kiln and other factors. Generally, one bubbling point is set for every 6~10m2 melting area. The distance between the bubbling points is 0.4~0.8m. The larger the bubble diameter, the fewer the number of bubbling points and the larger the distance between the bubbling points. In order to prevent excessive damage to the pool wall, the distance between the outermost bubbling point and the pool wall should not be less than 0.8~1m.
The arrangement of the bubbling points is related to the number of bubbling points and the size of the melting furnace. Smaller melting furnaces are mostly arranged in a single row, while large furnaces are arranged in two rows in a staggered manner. Bubbling points are mostly arranged in a straight line, and sometimes they can also be arranged according to the shape of the bubble boundary.
② Bubbling method, speed, size and pressure
There are two bubbling methods: low-pressure continuous bubbling and high-pressure pulse bubbling.
The pressure used for low-pressure continuous bubbling and the diameter of the resulting bubbles are smaller than those of high-pressure pulse bubbling, but the bubbling speed is faster. The bubbling speed depends on the stirring intensity of the glass liquid, usually 20~40 bubbles/min.
During high-pressure pulse bubbling, the bubbling speed is slower, 2~15 bubbles/min, and the bubble diameter is about 100~250mm.
The bubbling pressure depends on the viscosity and depth of the glass liquid and the method of gas supply. When the pressure is too high and the gas flow rate is too large, the normal bubble shape turns into a jet shape. In addition to large bubbles, small bubbles will appear in the glass liquid, which is not conducive to clarification. The bubbling pressure of low-pressure continuous bubbling is 0.03~0.05MPa. When the pressure is less than 0.02MPa, the bubbling operation is difficult to stabilize and is easy to "extinguish". The bubbling pressure of high-pressure pulse bubbling is 0.2~0.4MPa. In order to prevent the glass liquid from flowing back into the bubbling nozzle during the interval, it is necessary to maintain a balance pressure of 0.01~0.02MPa.
Structure and installation of bubbling nozzle
Since the temperature of the glass liquid at the bottom of the pool increases significantly after bubbling, the flow speed of the glass liquid near the nozzle is accelerated, especially the glass liquid in the immovable layer at the bottom of the pool is also involved in the flow, thus aggravating the erosion of the refractory materials at the bottom of the pool near the bubbling point. If not handled properly, it is easy to cause leakage and shorten the kiln life. Therefore, the bubbling nozzle should be resistant to high temperature, erosion, high strength, and not easy to oxidize. Commonly used materials include platinum and platinum rhodium (as the head of the nozzle), heat-resistant steel, corundum, silicon dimolybdenum, metal ceramics, etc. The inner diameter of the bubbling nozzle is generally 1~3mm, and several small holes are generally opened on the nozzle, which is convenient for bubble formation and can prevent the glass liquid from flowing back into the bubbling nozzle.
The nozzle brick should adopt the 41 oxidation method AZS brick with extremely strong corrosion resistance, and the two rows of pool bottom bricks before and after the nozzle brick should be 50~100mm higher than other pool bottom bricks, and the nozzle brick should be 50~100mm higher than the two rows of pool bottom bricks before and after the nozzle brick, forming a stepped shape
The degree to which the bubbling nozzle penetrates into the glass liquid is very important for bubbling. If the nozzle goes too deep, the stirring effect on the glass liquid is not strong enough, and the glass viscosity is low, so the glass liquid is easy to flow back into the nozzle during the bubbling interval; if the nozzle goes too deep, the erosion of the refractory material at the bottom of the pool will be too serious, which will affect the life of the melting furnace. The nozzle is generally 200~500mm higher than the bottom of the pool, and 50~100mm higher than the nozzle brick to prevent the glass liquid from flowing too fast to flush the bubbler nozzle and cause the bubbler tube to be blocked.
Bubbling air source
Purified compressed air is generally used as the bubble air source. The air from the non-lubricated air compressor is freeze-dried to remove moisture, and then purified by coarse and fine filters. Because the bubble nozzle is continuously running in the high-temperature glass liquid during the entire kiln cycle, the poorly purified air contains impurities such as water, oil and dust, which will scale on the tiny inner wall of the bubble nozzle, blocking the air outlet and causing "scaling blockage". The air supply pressure must be stable, and there must be a backup air source to prevent emergencies such as power outages.
Wechat Us 
