During the production and operation of the melting furnace, it is constantly eroded and washed by flames, waste gas, and molten glass. In about five years or more, some parts will be seriously damaged, threatening the normal production and the service life of the kiln body. This requires continuous maintenance. Under the conditions of adding glass water, not stopping production, and keeping the furnace running, when the kiln age reaches more than eight years, repairing a certain part is called "hot repair" of the furnace. Generally, the parts that are often hot repaired include pool wall bricks, regenerator checker bricks, port grate and slope grate, nozzle bricks, large grate or regenerator grate, corrosion holes, bubbler replacement, etc.

The meaning of hot repair

Thermal repair of the furnace is a necessary means to ensure the normal operation of the furnace and extend the life of the furnace. The kiln is the main thermal equipment for glass production. Daily maintenance alone cannot solve all problems. Thermal repair is to maintain the kiln so that it can better serve production. Parts with serious burn damage can be basically restored to their original structural state after hot repair to meet process requirements, maintain normal production, and extend the kiln life; hot repair can reduce heat dissipation in severely burned parts, saving energy and reducing consumption; for some Parts that have been proven to be incompatible with production conditions in practice can be improved, supplemented or transformed through hot repair to achieve the purpose of increasing production; hot repair is indispensable to ensure the safe operation of the furnace, avoid personal and equipment accidents, and improve economic benefits. Effective measures.

Hot repair process and refractory material selection

There is currently a new thermal repair welding process called ceramic welding technology. This process uses a mixture of dry refractory powder and ultra-fine metal powder, which is sprayed onto the high-temperature surface of the furnace refractory material with an oxygen stream. The metal powder in contact with the hot surface quickly ignites and burns, releasing a large amount of heat energy, causing the surface temperature of the furnace refractory material to reach over 2000°C, causing the mixed powder of the refractory material to melt quickly and tightly combine with the refractory material matrix to be repaired. At the same time, the molten material fills the holes, joints, gaps, etc. on the refractory bricks and restores them to their original good condition.

Hot repair gunning equipment consists of a powder mixer, a material delivery system, and control equipment that can adjust different injection parameters. If it is necessary to repair the inside of the furnace, a water-cooled spray gun that can penetrate deep to the left and right should be equipped.

The key to using ceramic welding technology for thermal repair is to form a material that is compatible and matched with the base material. The earliest used welding material is silicone material. The general chemical composition (mass fraction) of silicone material is: SiO2 95%, Al2O3 2.5%, CaO 2%, Fe2O3 0.5%. It is especially suitable for the siliceous roof of the furnace, such as the joint between the roof and the opening of the front wall, the corroded parts caused by flame erosion, etc. The repair process is not affected by the atmosphere in the kiln, and the thermal shock resistance and corrosion resistance of the welding layer can reach the original level.

For hot repair of fused cast AZS bricks, the surface should first be "cleaned" because at high temperatures the glass phase inside the zirconium corundum bricks will migrate to the surface of the bricks in a short time, and the volatile substances in the kiln will Contamination on the brick surface will form a glass layer. Therefore, before hot gunning, this part of the glass layer must be removed from the surface to form a good combination between the brick and the welding material.

For the fused cast AZS bricks of the side walls of the port mouth, the port roof and the breast wall, the chemical composition (mass fraction) of the gunning material is: SiO2 15.5%, Al2O3 50.5%, ZrO2 32%, Fe2O3 0.13%, TiO2 0.03 %, CaO 1.5%, MgO 0.05%, Na2O 0.07%, K2O 0.01%.

For high-aluminum materials, mullite welding material can be used. The Al2O3 content in the welding material can be as high as 98%. This material has excellent corrosion resistance and thermal shock resistance.

The refractory materials used for thermal repair should be made of the same material as the original design, or materials that will not react chemically with the masonry in contact and will not cause low-temperature eutectic melting. Fill the corroded parts according to the degree of damage, and then paint them immediately with hot repair mud. At present, there are many varieties of refractory materials in our country, including various sintered materials, electric fusion materials, ramming materials, etc., which creates conditions for hot repair.