Application of high-performance refractory materials in various parts for glass kiln
Refractory materials used in glass kilns are generally divided into the following 9 categories, including pool wall bricks, pool bottom bricks, charging pool bricks, flow cave bricks, cooling pool and forming pool bricks, kiln roof and breast wall bricks, front wall and Bricks for lattice walls, bricks for small furnaces, and refractory materials for special parts.
①Brick use for pool wall
The ideal pool wall brick material for the pool kiln for melting soda-lime-silica materials and boron-containing materials is fused zirconia corundum bricks. The inclined cast brick containing 33% of zr02, with the gate facing outward, is placed underneath. When melting alkali-free or low-alkali glass fiber, due to severe acid corrosion, the pool wall bricks should be made of AZS bricks or dense zircon bricks, or fused silica bricks.
②Brick use for pool bottom
Pool bottom tiles are required to be wear-resistant and have integrity. Nowadays, multi-layer composite bottom structure is mostly used. The multi-layer structure is generally built with an insulation layer under the main layer-clay bricks. A protective layer and a wear-resistant layer are set on the large clay brick. The protective layer is made of zircon sand ramming material or fused corundum ramming material. The wear-resistant layer is on top of the protective layer to protect the bottom of the ramming pool and directly contact the glass liquid. The fused AZS bricks with good corrosion resistance and wear resistance are commonly used. The use effect of this composite pool bottom structure is to reduce heat loss and prolong the life of the pool bottom. In order to prevent leakage of materials when melting glass containing heavy metal elements (such as lead glass) or glass with heavier corrosion (such as opal glass), a protective layer and resistance layer can be added to the original protective layer and wear-resistant layer. Grinding layer. The original protective layer and wear-resistant layer are also called secondary paving layers, which can be sintered AZS bricks or zircon bricks.
③Brick use for feeding pool
The bricks in the feeding pool are eroded by powdered material and molten glass, the material layer is worn out, the liquid flow is scoured, and the flame is affected, so the damage is more serious. High temperature, wear-resistant and corrosion-resistant materials are required, and fused zirconia corundum bricks containing 41% zrO2 without shrinkage are commonly used, and the brick thickness is increased and air cooling is strengthened. In addition to corner bricks, ordinary cast AzS-33 bricks can be used for other parts. Pouring kaolin bricks can be considered for the brick liquid in the lower charging pool.
④Brick use for liquid hole
In the kiln, the flow velocity of the molten glass in the liquid hole is the largest, and the convection is obvious, so the wear is serious and the corrosion is accelerated. Therefore, the liquid hole cover tile should be made of non-shrinkage AZS-41 bricks, and the liquid hole side wall bricks should preferably be made of the same material as the cover brick, at least non-shrinkage bricks should be used. Fused silica bricks are used when melting borosilicate glass.
⑤ Bricks for cooling pool and forming pool
The molten and clarified molten glass is already in the cooling and forming tank, and it has entered the later stage of the process. At this time, must not cause any defects (including bubbles, streaks, stones) to the molten glass. The cooling pool needs AZS-33 brick produced by oxidation method, which has a high precipitation temperature of the glass phase and will not bring bubbles to the glass liquid. The forming pool (such as the forehearth) should use fused α-β Al2O3 bricks or fused α-Al2O3 bricks.
⑥Bricks for kiln roof and breast wall
The damage characteristics of this part of the brick body are corrosion loss (mainly alkaline sulfate condensation, formation of honeycomb corrosion loss) and burning loss. It is required to use a material that is extremely stable to alkali vapor at high temperatures, and has a high load softening temperature and creep resistance. You can choose silicon bricks, high-quality silicon bricks and fused AZS-33 bricks.
⑦Bricks for front wall and lattice wall
These are the front and back walls of the melting department. They also have two damage characteristics: erosion and burning. In addition, the front wall is abraded and eroded by batch materials and scoured by overflowing flames. It is one of the weak parts of the kiln. At present, fused AzS-33 bricks are used, and high-quality silicon bricks and sintered Azs bricks are also used in combination (such as L-shaped hanging walls). In addition to the use of high-quality silica bricks, the front wall also needs to be air-cooled.
⑧ Bricks for small furnace
It can be divided into fire vents, small furnace necks, nozzle bricks and other parts to consider. Bricks for small furnaces are required to be able to withstand high temperature, corrosion, erosion, and have a certain degree of thermal shock resistance. If you burn producer gas (small heat load), you can use silica bricks or even large kaolin bricks. If you burn high-calorific value fuels (high heat load), fire vent wall bricks, vent side wall bricks, floor bricks, and oblique bricks can be used. Fused AZS-33 bricks are used for interlayer bricks, tongue bricks and nozzle bricks. The bottom plate can also be sintered dense corundum bricks.
⑨The selection of refractory materials for special parts
There are some special parts on the masonry of the kiln, such as bubbling holes, kiln ridges, electrode holes, inspection holes, and measuring holes. They have a special purpose, but also have their own damage characteristics. The bubbling hole bricks will be strongly worn and corroded by the rapid circulating liquid flow caused by bubbling. The large temperature difference between the inner and outer surfaces of the bubbling hole bricks will produce large mechanical stress, which is easy to cause cracks. Kiln bricks will also be damaged by severe high temperature liquid flow. Both of these two types of bricks can be produced by oxidation method without shrinkage cavities containing 41% Zr02 fused zirconia corundum bricks. The electrode hole brick is strongly corroded by the circulating liquid flow around the electrode, and the large temperature difference in the brick caused by the cooling of the electrode causes a large mechanical stress, which leads to radial cracks around the brick hole. Therefore, bricks are required to have a certain degree of thermal shock resistance and higher electrical resistance in addition to corrosion resistance and wear resistance. When choosing a material, in addition to its electrical properties, the conductivity of the molten glass and the arrangement of electrodes must also be considered. Generally, the non-shrinkable fused zirconia corundum bricks with 41% Zr02 produced by the oxidation method have poor thermal shock resistance. You can consider using fused silica bricks or dense zirconia bricks produced by sintering. The measuring hole and inspection hole bricks are subject to long-term erosion by the overflow flame in the kiln, and are easily burnt and cracked. Customized fused zirconium corundum bricks containing 33% Zr02 are commonly used.
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