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Application of Ceramic Welding and Repair Technology in Glass Furnaces

The improvement in the maintenance level of glass furnaces is attributed to the continuous progress in material performance and the ongoing development and maturity of process technology. Ceramic welding and repair technology perfectly combines these two aspects. Since its extensive application in the maintenance of various thermal kilns, this technology has made it possible to perform in-situ thermal repairs on damaged areas inside the furnace, significantly extending the furnace’s lifespan, reducing overall costs, and indirectly enhancing product quality.

I. Why Introduce Ceramic Welding and Repair Technology to Glass Furnaces

Certain areas are challenging to maintain externally, making ceramic welding and repair technology a convenient solution for issues such as:

1.1 Firing of glass furnaces using furnace gas and the leakage of hot gas through the separating wall of the gas storage chamber.

If black smoke continues to be emitted without changing the chimney direction, it is likely that hot gas is leaking through the separating wall. According to data, a furnace with a 60 square meter surface area can burn an additional 2 tons of coal per day due to gas leakage. Moreover, as the leaking area continues to burn, there is a possibility of the separating wall collapsing, leading to forced shutdown and cold repairs.

1.2 Various parts of small furnace spouts

Small furnace sloping tongues, shelf tongues, and separating walls are often quickly damaged. Sloping tongues and shelf tongues are challenging to repair externally, yet they can affect flame combustion, impacting energy consumption and glass quality.

1.3 Large shelf corner bricks

Due to fuel or upper clearance sealing issues, shelf corner bricks may be damaged. Since large shelf corner bricks bear weight, they need to be repaired.

1.4 Large holes at the top of the furnace

If the maximum size of the hole far exceeds the thickness of the shelf, it is undoubtedly a significant hole. Traditional repair methods are prone to dropping refractory materials into the furnace, and the strength cannot reach the original level. The best effect is achieved by hanging the bricks and then performing ceramic welding and repair.

1.5 Hook bricks

The reversal of hook bricks is a common problem for many glass factories. The main issue is that after the reversal, they can burn into the support plate, affecting the furnace’s safety.

For the above areas, traditional thermal repair methods are ineffective and costly, with poor safety. Therefore, ceramic welding and repair technology need to be introduced. As long as the area is above the liquid level, ceramic welding can be used for repairs.

II. How to Effectively Conduct Ceramic Welding and Repair

2.1 Detect furnace interior problems early

Glass factories should establish regular contacts with capable ceramic welding and repair companies to conduct periodic endoscopic inspections of furnace interiors. Based on the analysis of images, repairs should be prioritized for safety-related issues, such as the firm resolution to repair weight-bearing parts.

The level of internal furnace inspection depends on whether the welding and repair company can provide professional reports, with consideration given to the presence of professional engineers rather than sales personnel. The report should neither exaggerate nor overlook problems.

To conduct a proper internal inspection, glass factories should prepare oxygen and cooling water at the furnace head. Temporary shutdowns may be necessary when required.

2.2 Immediate repairs reduce costs

Timely ceramic welding can reduce the amount of maintenance work, thereby lowering costs. Once furnace erosion occurs, it rapidly advances in the eroded area, similar to a domino effect.

Therefore, for areas not severely affected during inspection, the repair project may significantly increase during maintenance. This situation is common in glass thermal repairs. One of the principles of glass furnace thermal repair is to act promptly. Timeliness is crucial. Adequate allowances should be considered for thermal repairs—better more than less. Repairs should not be delayed for an extended period after furnace inspection.

2.3 Planned annual thermal repairs

It is advisable to perform ceramic welding annually during the operational cycle of the furnace, especially for furnaces firing coal tar or petroleum coke.

2.4 Combining with traditional thermal repairs

For example, when repairing large holes on the shelf, glass factories can hang the bricks themselves and then perform internal welding and repair.

III. Clarification of Several Misconceptions

3.1 New furnaces do not need repairs

In terms of maintenance, there is no distinction between old and new furnaces; the only difference lies in whether repairs are necessary. Some experienced engineers have mentioned that furnaces should be prepared for thermal repairs on the day of commissioning. For instance, if there are issues with hook bricks after kiln roasting, timely repairs are not only necessary but also responsible. In this way, the furnace can establish the foundation for safe operation throughout the entire kiln period.

Furnaces that undergo constant inspections and repairs may seem to have numerous problems, but they often exceed their service life.

3.2 One-time permanent repairs after thermal repairs

No thermal repair can be permanent. When problems are discovered in the furnace, they may be related to raw materials, fuel, operating methods, materials, design, etc. Glass factories need to identify the causes and make adjustments promptly. The welding and repair company can guarantee that the repaired parts will function normally for a certain period.

IV. Requirements Achieved by Ceramic Welding and Repair

Before and after welding, comparative photos should be taken. The repaired area’s internal surface should be smooth, tightly integrated with the original material, not show signs of heat transmission or reddening externally, and have complete sealing.

V. Comparison with Traditional Thermal Repairs

No.ItemTraditional Thermal RepairCeramic Welding and Repair
1Impact on Production1. Sometimes, kiln pressure and flow rate need to be reduced. 2. Easy to drop refractory materials into the furnace.1. No requirement to reduce kiln pressure or flow rate. 2. Almost no material drops.
2Repair TimeLongShort
3Labor IntensityHighLow
4Number of ParticipantsManyFew
5Engineering MaterialsZero expansion silica bricks, electrically fused bricks, and various amorphous heat repair materials.Specialized non-structured welding and repair materials, also requiring oxygen and a small amount of nitrogen.
6Repair PrincipleFrom the outside to the inside.From the inside to the outside.
7Repair ScopeSmall.Above the liquid level.
8Required Equipment and AncillariesSimple equipment, such as protective fans, heat repair materials, mixing tanks, trowels, and pokers.Professional equipment, including welding guns, water pipes, material pipes, mixers, pressure pumps, busbars, protective air ducts, quick connectors, and high-pressure hoses.
9OperabilityRelatively difficultRelatively easy
10Labor Protection SuppliesGenerally cotton clothing, cotton pants, etc.Professional supplies.
Conclusion

The application of ceramic welding and repair technology in glass furnaces has solved many challenges in furnace thermal repairs for glass companies. It has bridged the gaps in the development path, contributing to the advancement.

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