What are the methods for thermal repair of glass furnace pool wall tiles

The walls of domestic glass melting furnaces are mostly made of various types of fused zirconia corundum bricks. Their quality has been greatly improved in recent years, but there is still a large gap compared with similar bricks in advanced countries. Domestic kiln pool wall tiles generally only have a safety period of 2 to 3 years. Therefore, during the entire service life of the furnace, the severely damaged parts of the tank wall usually need to be hot repaired once or twice. The upper pool wall tiles near the hot spots are most severely burned and corroded. In severe cases, only 20~30mm is left. If not repaired in time, there is a risk of water leaking from the glass. Therefore, the melter and kiln bricklayer must pay attention to and measure the remaining thickness of the pool wall bricks, and propose the parts to be hot repaired for the technical department to formulate a hot repair plan.

There are three methods for hot repairing upper pool wall tiles.

(1) Cooling water pipe method

 When there is a gap of 80~100mm between bricks, a seamless steel pipe with a diameter of 20~50mm can be used and immersed along the eroded pool wall 50~80mm below the liquid level inside the kiln pool to solidify the nearby glass liquid and maintain the outlet water temperature. Around 50℃. Although this method is effective, it increases heat and water consumption and can only be used on the upper part of the pool wall. It is difficult to be effective when most of the entire brick is eroded and thin, so this method is rarely used.

(2) External iron brick method

 (Building bricks, tying bricks) In the middle and later stages of the melting kiln, when the thickness of the pool wall is very small, bricks can be tied to the pool wall. When the iron brick is eroded to less than 30mm thick and has a wolf tooth shape, an 80~100mm thick iron brick (also called a tied iron brick) can be attached to the outside, using No. 33 or 36 oxidation method non-shrinkage zirconium corundum Bricks, specifications are 300mm × 400mm × 100mm. Use a heating box to heat the bricks on the pool wall until the temperature of the bricks reaches about 900°C. Then use special tools to take them out on site and tie them from the No. 1 small furnace to the pool wall corresponding to the hot spot. Fixed in position. The contact surface between bricks should be as smooth as possible, and the gaps between the bricks should be small. Each time bricks are tied and the air volume of the pool wall is appropriately increased, it can generally be used safely for about 2 years. Bricks can generally be tied 2 to 3 times in one kiln period. If the kiln is more than 8 years old and still needs to lay bricks, a descending liquid surface should be used to bring it to a safe position, the original tiles should be removed, and then the tiles should be reinstalled.

(3) Top iron brick method

 For layered pool walls, this method can be considered when the top layer is 400~600mm high. First prepare enough iron bricks, arrange them in advance, and preheat them. The cooling workers install the supporting steel frame and prepare all the tools. After the new iron bricks are discharged, they remove the gap bricks and clean them. They use clay bricks to block the fire opening, and then place hook-shaped water bags at both ends. After the jacking screw is installed, stop 40~60mm and then start jacking. The first push is 40~60mm, the second push is 70~80mm, and the third push is completed, with an interval of about 40mm each time. Remove the hook-shaped water bag and place gap bricks. During operation, please note that the old iron bricks on both sides that do not need to be replaced will tilt inward, and the top screw must be moved down to less than 3/4 of the top surface of the iron bricks. Several jackscrews should be pushed forward evenly to ensure balanced movement of the new iron bricks. When the bricks are topped, the gap bricks are removed and the air ducts are removed, so that cold air is blown into the kiln and the temperature drops. Therefore, the melting workers need to cooperate to control the temperature and pressure of the kiln as stable as possible to maintain normal production. At present, most of the pool walls are integrated.

(4) Use retaining water bag and cooling water hook

 At present, most float glass manufacturers adopt a "double high heat load" melting operation system to increase the temperature of No. 1 to No. 2 small furnaces, which will correspondingly increase the temperature of the feeding pool, causing the root of the stockpile to be more "living". Due to the melting operation, the temperature of the pool walls on both sides is lower than the temperature in the middle of the furnace. The resulting transverse convection of molten glass will lead the advancing material pile to the pool wall. Furthermore, large float glass melting furnaces mostly use two blanket-type Feeder, each material strand cannot adjust the direction of the material strand independently. The longer the time, the easier it is to form an "inverted figure-eight" material pile that is deflected to both sides of the pool wall. The skewed pile of material directly adheres to the pool wall bricks of the small furnace in the chemical area and gradually melts, which has a greater scouring effect on the pool wall and accelerates the erosion and erosion rate of the pool wall bricks in the small furnace in the chemical area.

①Middle solid water pipe

 The temperature of the glass liquid at the pool walls on both sides increases. When the temperature difference between the middle part of the furnace and the two sides of the glass liquid is reduced and the transverse convection is balanced, the stability of the material pile can be ensured without deflection, which has a good effect on preventing material deviation, reducing tank wall erosion and improving glass quality. For large kilns (such as 900t/d), it has limited effect, but some manufacturers are still using it.

② Pool wall retaining water bags on both sides

 If the melting operation is difficult to correct for the "inverted eight-shaped" material pile caused by specific reasons in the melting furnace, a 76mm, 7~8m long retaining water bag can be installed on both sides of the feeding pool to stick to the glass. The liquid level is placed at an angle slightly tilted toward the center of the furnace. The skewed material pile is forcibly blocked within the effective length of the blocking water bag, changing the tilting direction of the material pile, reducing the extent to which the material pile is close to the wall of the small furnace in the chemical area, which has a certain effect on reducing the erosion of the material pile against the pool wall. effect. For large kilns, it has limited effect, and some manufacturers are also using it due to operating habits.

③Cooling water hook on pool wall

 Since the pool wall is constantly being eroded by erosion and the furnace has been running for a certain period, when the thickness of the pool wall bricks in the chemical area is thin (about 100mm), some manufacturers install cooling water hooks from the lower gap bricks. Generally, a small furnace pool wall Install 2~3 cooling water hooks. The water hooks are L-shaped and have a length of 800~1000mm. The cooling water hooks are close to the inside of the pool wall and extend into the material layer to a depth of 60~70mm (specifically determined according to the height of the lower gap brick). The hook holds the skewed material pile so that it does not stick to the pool wall, and can also reduce the viscosity of the glass liquid there, reduce the erosion rate of the material pile on the pool wall, and protect the pool wall. However, the cooling water hook on the pool wall is a double-edged sword, which has advantages and disadvantages. Due to the cooling effect of the cooling water hook on the pool wall, the temperature difference between the middle and both sides of the furnace is increased, making it easier for the material pile to deviate. You can consider using internal hanging bricks to replace the cooling water hooks to solve the shortcomings of the water hooks.