1. About the structural design of the liquid hole
The liquid hole is an important part of the glass furnace. The melted, clarified, and homogenized glass liquid passes through it and enters the distribution channel and supply channel for further homogenization and cooling, and finally enters the molding equipment for production and molding. There are 360~400t of molten glass passing through this narrow channel every day, and the erosion and wear of the molten glass on it is great. Moreover, the working environment of the liquid hole is poor and the surrounding temperature is high. Once there is a problem, it cannot be replaced. Therefore, fused AZS41# bricks or sawn bricks with better corrosion resistance are used in liquid flow holes. The fused AZS brick has an upward corrosion hole at the interface of the solid, liquid and gas phases. The fused AZS brick is the solid phase, the glass liquid is the liquid phase, and the bubbles remaining in the glass liquid are the gas phase, resulting in liquid holes. The cover bricks eroded more than other places. In 5 to 6 years, the thickness of the cover bricks was eroded upward by 300 to 400 mm. After the cover bricks of the liquid hole were eroded by 300 to 400 mm, the depth of the glass liquid was shallower, equivalent to the original depth. The depth of the kiln pool has been reduced by 300~400mm, and the output of the kiln will definitely be affected. In order to meet the output, the only way to increase the furnace temperature is to increase the energy consumption. After a few years, the furnace cover and other furnace bodies will be burned, the furnace body will become thinner, the internal temperature will increase, and the heat dissipation of the furnace body will further increase.
In summary, the structure of the liquid tunnel will affect the life of the kiln, the discharge volume and energy consumption. In view of the erosion mechanism of the liquid hole cover brick, we designed the contact surface between the liquid hole cover brick and the glass liquid to be inclined. The bubbles in the glass liquid are not easy to attach to the liquid hole cover brick, thus greatly slowing down the process. It prevents the erosion of the liquid hole cover bricks and extends the life of the liquid hole, which also extends the life of the kiln.
2. About the bottom structure of the pool
The bottom structure of the kiln can also easily affect the life of the kiln, especially the kiln with high white material or crystal white material. Due to its good heat permeability, the temperature of the bottom of the tank is high, and some metal objects will inevitably be brought into the batch materials. , metal objects corrode the fused AZS more severely (downward corrosion holes). Once the fused AZS bricks are corroded and the glass liquid penetrates under the floor bricks, “upward corrosion holes” will occur, forming stalactites. Erosion will quickly corrode the AZS bricks on the bottom floor, causing great harm to the safety of the entire pool bottom and affecting the life of the kiln. In serious cases, material leakage accidents at the bottom of the pool may occur.
In order to prevent such incidents from happening, firstly, the entry of metal objects in the batch materials must be strictly controlled, and secondly, the anti-leakage structure at the bottom of the pool must be strengthened. The pool bottom structure designed this time is a multi-layer composite structure.
3. Length and width of melting pool
Once the melting rate is determined, the melting area of the kiln is determined. The design philosophy we adhere to is: when considering the coverage of the flame, we not only consider the width of the flame, but also pay more attention to the length of the flame. When designing, we draw lessons from the principles of float glass furnaces, that is, we distinguish the five stages of glass melting (1. silicate reaction, 2. glass formation, 3. glass homogenization, 4. glass clarification, 5. Glass cooling), these five melting stages are carried out in different spaces and at the same time. Therefore, we believe that the design of the horseshoe flame furnace should have a larger aspect ratio within the length that the flame can reach, so that there is a certain area for the clarification and homogenization of the glass liquid. That is, if the flame can reach it, the absolute length of the kiln must be larger.
In order to reduce dead spots and facilitate the flow of molten glass, we designed the front pool wall bricks of the melting pool into a figure-eight shape.
4. Depth of melting pool
At present, the melting pools of more advanced kilns are divided into shallow pools and deep pools. In order to strengthen hot spots and improve the quality and output of glass, kiln sills are generally installed. We designed a shallow pool in front of the kiln sill and a deep pool behind the kiln sill. In front of the kiln sill is the melting zone (also called the primary melting zone). The surface of the glass liquid in the melting zone is covered with thick batch materials and foam formed during the melting and decomposition of the batch materials. They are poor conductors of heat and are a layer of heat insulation. . Since the heat insulation layer affects the penetration and transfer of heat, the depth of the shallow pool should not be too deep. If it is too deep, a thick immobile layer or slow-moving layer will be formed at the bottom of the pool. The thickness will change with changes in the temperature of the bottom of the pool or changes in the discharge volume, thereby adding to the natural convection of the glass liquid, thereby affecting the quality of the glass liquid; and the glass liquid in these immobile layers or slow-moving layers adds to the natural convection of the glass liquid. After convection, repeated heating of the glass liquid will occur, increasing energy consumption.
Behind the kiln sill is the clarification and homogenization area, also called the fine melting area (referred to as the deep clarification tank). We should deepen the depth of the tank in this area. The deep clarifier plays a very obvious role in improving the quality and output of glass furnaces and reducing energy consumption. First, it increases the volume of the glass furnace and prolongs the residence time of the glass liquid in the furnace; second, “The clarification process of glass refers to the process of eliminating visible bubbles. From a formal point of view, this process is a simple fluid Mechanical process, in fact it is a complex physical and chemical process. The clarification speed of the glass liquid is related to the viscosity of the glass liquid, and the viscosity (including surface tension) is related to the temperature of the glass liquid. If the depth of the deep clarification tank is too deep, although the bubbles The static pressure of the molten glass is relatively large, but due to the low temperature of the molten glass, the viscosity of the molten glass is high, making it difficult to discharge the bubbles. According to computer simulation technology, the temperature of the glass liquid at the bottom of the deep clarification tank should be considered to be no less than 1300°C. Therefore, the depth of the deep clarification tank of this kiln is designed to be 1300mm. When designing and calculating the depth of the deep clarification part of the melting tank, not only the heat permeability of the glass must be considered, but also the size of the kiln. For the same type of glass, large kilns can be appropriately deeper.
5. Structure of the feeding tank
The distribution of the batch materials in the melting pool plays a very important role in the melting speed of the batch materials. The wider the feeding port, the wider the feeding machine. With the same feeding amount, the thickness will be thinner. The wider the material city formed, the higher the heat utilization rate, and the faster the batch melts. Due to the large discharge volume of the kiln this time, although unilateral feeding can reduce the escape loss of radiant heat and high-temperature airflow, considering the long-term operation, the wear and tear of the feeding machine and other batch material conveying systems will increase, and failure is inevitable. It is difficult to ensure normal feeding and discharging of materials, so a symmetrical bilateral feeding pool structure should be adopted. The concept we adhere to when designing the feeding pool is: lengthen the feeding pool, which allows the batch materials to undergo a relatively complete silicate reaction in the pre-melting pool. The surface of the batch materials entering the furnace has already begun to undergo silicate reaction, and the surface has already It becomes sticky, and the airflow of the flame will not easily blow up the fine powder on the surface of the batch material, thereby reducing the clogging of the regenerator grid. Reduce dust flying thereby reducing the erosion of the furnace body and extending the life of the kiln.
The shape of the feeding pool should be determined by the type of feeding machine. Practice at home and abroad has proven that the swing wrap-in feeding machine has the best feeding effect and energy-saving effect at present, and can save about 5% of energy. The energy-saving principle of the swing wrap-in feeder is as follows:
(1) Generally, the batch materials added into the furnace by the feeding machine float on the surface of the glass liquid. Because the batch material is loose, its thermal conductivity is very low and the melting speed is slow. A wrap-in feeder is used, which squeezes the batch materials into the glass liquid. During this process, the high-temperature glass liquid is squeezed up to fill the pores in the batch materials, which increases the thermal conductivity of the batch materials. If the feeder is installed If adjusted well, the batch material will be partially wrapped in the glass liquid like dough, thus the melting speed will be greatly accelerated, the output amount of material can be increased due to fast melting, and the energy consumption will be reduced.
(2) The swing wrap-in feeder can swing and feed materials in three directions: left, middle and right. The number of pushing materials in the three directions can be set and adjusted arbitrarily, so that the material pile is distributed very evenly in the melting pool and the area of the melting pool is fully utilized. , which effectively utilizes the radiant energy in the flame space and improves the utilization rate of the melting pool, thus further accelerating the melting speed.
(3) Since the materials are fed in three directions respectively, the batch materials are in small piles surrounded by the glass liquid in the furnace, which increases the contact area with the glass liquid and realizes thin layer feeding.
(4) From another perspective, the swing wrap-in feeder also has the advantage of extending the life of the kiln. Since the swing wrap-in feeder regularly pushes the batch materials in three directions, the batch materials are at the rear end of the melting pool. Evenly distributed, it is in direct contact with the pool wall bricks for a short time, or even not directly in contact with the pool wall bricks, thus extending the life of the pool wall bricks, because the batch material erodes the pool wall bricks much more than the glass liquid.