The glass melting furnace is composed of different parts. When selecting refractory bricks for the glass furnace, we comprehensively consider the high temperature performance, chemical stability, thermal stability, volume stability and mechanical strength of each part, and at the same time do not pollute the furnace，the molten glass in the pool does not affect the quality of the molten glass. This article will introduce in detail how to choose refractory bricks for glass furnaces.
1. What are the structural characteristics of the float glass melting furnace?
The float glass melting furnace belongs to the cross-fired glass melting furnace. According to the functions of each part, its structure is divided into four parts: glass melting, heat source supply, waste heat recovery, and smoke exhaust, gas supply. The melting part is further divided into feeding port, melting, refining and homogenization zone, cooling zone and separation device, etc.
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2. What is the structure and material of the feeding port?
The feeding port, also known as the doghouse, is composed of the feeding pool and the upper retaining wall (L-shaped front face hanging wall).The temperature of the feeding port is generally 1100~1400 ℃, which plays the role of pre-melting and sealing for mixed materials.
① Many float glass melting furnaces have adopted a feeding pool with the same width as the melting part, which makes the material layer thinner and can prevent partial material. The refractory material used for the wall of the feeding pool (brick thickness 250mm) is AZS36# zirconium corundum brick;
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②L-shaped hanging wall (brick thickness 305mm) is widely used for the upper retaining wall. The hanging wall is suspended separately, and the feeding pool can be lengthened, which not only strengthens the sealing and reduces the flying of materials, but also strengthens the pre-melting effect on the batching materials. ;The hanging wall adopts imported high-grade silica bricks, and also adopts fused mullite or zirconium corundum bricks;
③The front end of the upper retaining wall (ie the front end of the nose area of the L-shaped hanging wall) is hung with a row of flame-blocking bricks or a group of water bags, which mainly play a sealing role. The flame-blocking bricks are made of low-expansion silica bricks.
3. What is the structure and material of the melting part?
The melting part is the part where batch materials are melted and the glass liquid is clarified and homogenized; due to the melting method of flame surface heating, the melting part is divided into two parts, the upper part is called the flame space, and the lower part is called the kiln; the temperature of the melting part is generally 1400~1600℃.
①The flame space is a space system composed of a breast wall , a large arch, a front wall and a rear gable. The flame space should be able to satisfy the complete combustion of the fuel, ensure the supply of heat required for the melting of the batch material into glass and its clarification, and should minimize heat dissipation and seal.
a. The breast wall (brick thickness of 300 mm) in the melting area, including burner bricks, hook bricks and lower clearance bricks (brick thickness of 230 mm), the use conditions include powder scattering, shedding after melting of the dome and hot flames Therefore, it is advisable to use AZS33# zirconium corundum bricks; the breast wall in the refining area (brick thickness 350mm), its use conditions have no unfavorable factors in the melting area, so high-quality silica bricks can be used, so that the matching use saves investment;
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b. Big arch (brick thickness is about 500mm, with 3*64mm light silica bricks outside), its use conditions are high-temperature alkali vapor and hot flame gas, generally high-quality silica bricks (some melting areas are imported high-quality silica bricks , the refining area is domestic high-quality silica brick);
c. The upper gap (special shape), its use conditions are the same as the big arch,and it plays the role of separating the large sill silica brick and the breast wall AZS zirconia corundum brick to avoid their contact reaction. High-quality zircon bricks should be used (note: silica bricks are acidic, zirconium corundum bricks are alkaline, and zircon bricks are neutral);
d. The front wall and the rear gable (brick thickness is about 350mm), of which the front wall has been described in Clause 2. The use conditions of the rear gable are same as the breast wall in the clarification area, and high-quality silica bricks are used;
e. Supporting iron plate, in order to facilitate the expansion of the kiln and the hot repair during normal production, the breast wall and the big arch are supported independently; the supporting iron plate plays the role of supporting the breast wall, and the inner edge of the supporting iron plate is blocked by the hook brick at the bottom of the breast wall to prevent burnout.
②The kiln is the place where the batch materials are melted into molten glass and clarified and homogenized. Try not to pollute the molten glass. It is rectangular and has enough steel structure support at the periphery and bottom. The walls and bottom of the pool are built with large bricks.Reduce the amount of material processing and facilitate construction and reduce erosion;
a. The pool wall (brick thickness is about 250mm), its use condition is that it is in contact with the glass liquid and washed, and the upper edge of the pool wall in the melting area is also subject to the scattering of batch materials and flame ablation, all using AZS36# zirconium corundum bricks;
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b. The upper layer of the pool bottom (paving brick 75mm, middle ramming material 55mm, lower clay large brick 200mm), its use conditions are contact with glass liquid and scour, gas-liquid phase upward drilling erosion, paving bricks are made of AZS33# zirconium Corundum brick, the ramming material is zircon.
4. What is the usage of the cooling part (ie the working part)?
①The cooling part is the part where the molten glass is further homogenized and cooled, and is supplied to the next forming process to provide pure, transparent, uniform and stable temperature of the glass;
②Operating holes can be reserved on the breast wall of the upper space for the space water bag or dilution air to enter, which can be used to reduce the space temperature and glass liquid temperature in the kiln as required.
5. What is the structure and material of the cooling part (ie the working part)?
The cooling part is the upper space and the kiln, and the operating temperature is about 1200~1400℃;
①The upper space is a space system composed of a breast wall, a large arch, and front and rear gables;
a. For the breast wall and gable wall (brick thickness 300mm), the use conditions are that the temperature is low and the change is small, no dust is scattered, and ordinary silica bricks are used;
b. For the large arch bricks (400mm thick bricks), the use conditions are that the temperature is low and the change is small, no dust is scattered, and ordinary silica bricks are used.
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②The kiln in the cooling part is composed of two parts: the wall and the bottom, which are rectangular and have sufficient support from the outer and bottom steel structures;
a. The pool wall (brick thickness is 200mm), its use condition is that it is in contact with the glass liquid and washed away, so it cannot have any pollution to the glass liquid. It is advisable to use α·β fused corundum bricks or AZS33# zirconium corundum bricks;
b. The bottom of the pool (the upper paving brick is 75mm, the middle ramming material is 55mm, and the lower layer of clay big arch is 200mm), the use conditions are that it is in contact with the glass liquid and washed away, without any pollution to the glass liquid, with high mechanical strength, the paving brick is also made of α·β fused corundum brick, and the ramming material is zircon.
6. What are the separation devices of the furnace? What is each used for?
Separation device has gas space separation device and glass liquid separation device
①Gas space separation devices generally include flying arch and suspended walls, and glass liquid separation devices include necks, cooling water bags, dam wall, etc.
a. The flying arch is to reduce the height of the breast wall, that is the arch that connects the front and rear of the neck with the gable, and that is the arch enters the flow channel of the cooling part, both play the role of blocking the convection of the space gas, and generally reduce the temperature by 30~50 ℃;
b. Suspended walls (mainly U-shaped) are often used in conjunction with the neck. Some suspended walls can be moved up and down, which is easy to adjust the opening, and can almost completely separate the front and rear spaces and play a large cooling effect.
c. The neck is a narrowed kiln between the melting part and the cooling part. It is used in conjunction with the flying arch and the separation wall to separate the gas space between the melting part and the cooling part and the glass liquid, thereby reducing the glass liquid temperature;
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d. The cooling water pipe is composed of a group of round or square steel pipes passing through the cooling water, and the height of the water pipe is determined according to practicality. After the glass liquid near the cooling water pipe is cooled, it forms a moving layer with high viscosity, which forms a retaining wall and has a large cooling effect. Control the quality of the molten glass entering the cooling part;
e. The dam wall is a slope-type partition that can block the convection of the glass liquid. There are multiple kiln sills in the longitudinal direction of the kiln, such as the refining belt. The dam wall can be set when entering the neck and the front end of the working part.
7. What is the structure and material of the small furnace?
The small furnace is an important part of the glass melting furnace. It is a device that mixes the fuel and the preheating air and organizes the combustion. When the fuel is heavy oil, the small furnace only acts as a channel for the preheating air to enter or the exhaust gas in the kiln to be discharged. The channel enclosed by the small furnace arch, the small furnace wall and the small furnace bottom, the operating temperature is 1400~1600 ℃.
①Small furnace arch and wall (brick thickness 200mm), the use conditions are powder scattering and high temperature change, AZS33# zirconium corundum bricks should be used;
②Small furnace bottom (the upper paving brick is 75mm, the middle zirconium insulating layer is 5mm, and the lower clay brick is 114mm), and its use conditions are the scattering of powder and the high temperature change. The material of the upper paving brick is AZS33# zirconium corundum brick.
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8. What is the usage of the regenerator?
The regenerator uses refractory materials as regenerators’ body (called checkers) to accumulate part of the heat from the flue gas discharged from the kiln, and is used to heat the combustion-supporting air entering the kiln. In this way, the waste heat of the flue gas can not only be utilized, but also the combustion-supporting air can be heated to a higher temperature, which is beneficial to increase the working temperature.
9. What is the structure and material of the regenerator?
The regenerator is composed of front and rear walls, partition walls and checkers in the regenerator. The operating temperature is divided into the upper part of 1200~1500℃, the middle part of 800~1200℃, and the lower part of <800℃.
①The arch of regenerator (brick thickness 350mm, with 3*64mm insulation bricks), its use conditions are powder scattering, high temperature change, redox reaction, and the material is high-quality silica brick;
②The target wall of the regenerator (brick thickness of 350mm, with 146mm clay bricks and 178mm insulation bricks) has the same conditions of use as the regenerator, and the material is AZS33# zirconium corundum brick;
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③Main wall and partition wall: the upper part (brick thickness 350mm), the use conditions are the same as the arch of regenerator, the material is high-quality silica brick; the middle part (brick thickness 230mm), the use condition is the temperature change of medium temperature, the material is high alumina brick or magnesium brick; the lower part (brick thickness 350mm), the use condition is low temperature change, and the material is low porosity clay brick.
④Checker brick (cylindrical, inner cavity 160mm, wall thickness 40mm)
a. There are 4 layers on the upper part. The use conditions are the scattering of powder and the high temperature change (1200~1400℃), and the material is magnesia zirconium 74/16% brick;
b. The upper 13 layers, the use conditions are high temperature change (1100~1300 ℃), redox reaction, and the material is MgO97% brick;
c. There are 20 layers in the middle and upper parts, the use conditions are the temperature change of medium and high temperature (1000~1200℃), the erosion and redox reaction of sulfate, and the material is MgO95% brick;
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d. 22 layers in the middle, the use conditions are the condensation of sulfate and alkali vapor, the temperature change at medium temperature (800~1000℃), and the material is 72MgO~12CrO bricks.
e. The lower part has 10 layers, the temperature change at low temperature (600~800℃) and the temperature load, and the material is clay brick with low porosity.
⑤ The arch of bottom furnace, the use conditions are the same as the bottom checker bricks, and the material is clay bricks with low porosity.
10. What is the principle of selection of refractories for glass melting furnaces?
①Meet the necessary performance, such as high temperature performance, chemical stability, thermal stability, volume stability and mechanical strength;
② Does not pollute the molten glass in the kiln, and does not affect the quality of the molten glass;
③Long service life as possible;
④ There is no contact reaction between adjacent bricks at high temperature;
⑤ As little material consumption and heat dissipation loss as possible;
⑥ Use high-quality materials for vulnerable parts and general materials for other parts to achieve "reasonable matching and synchronous kiln age".
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11. Why does the melting department choose high-quality silica bricks?
①Due to the direct contact with or close to the hot flame in the melting part, the flame flows in a vortex shape, which is strong and powerful, and has a certain scouring effect; the maximum temperature of the flame is between 1500 and 1600 ° C, and it is mixed with batching dust, alkali vapor and sulfide. and carbon micro-materials, so the brick body of the big tuyere is easy to be damaged and burned;
②The high-quality silica bricks have high high-temperature structural strength (the softening point temperature under load reaches 1640~1700℃). Low creep rate and strong alkali vapor resistance (the disadvantage is that the thermal shock resistance is slightly lower), so it can be fully applied to the conditions of use of the sling.
12. Why choose fused zirconium corundum bricks for the pool wall of the melting part?
Because the melting part pool wall is in contact with the glass liquid, especially the position of the liquid level line is the three-phase interface of gas, liquid and solid, which is very easy to be eroded and washed, coupled with the fluctuation of the liquid level and the high temperature effect of the molten batch. Therefore, the material of the pool wall bricks is required to be resistant to high temperature, erosion, and wash, without causing defects to the glass liquid, with certain thermal shock resistance and low thermal conductivity. The fused zirconium corundum brick just meets the above requirements, can withstand high temperature - its refractoriness is as high as 1780~1800 ℃, has strong corrosion resistance to glass liquid, and is resistant to erosion - almost no pollution to glass liquid, suitable for melting part to resistance thermal shock and low thermal conductivity .
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13.Where can purchase high quality refractory bricks?
Zhengzhou Shennan Refractory (SNR) is well known in domestic markets and abroad for quality of refractory bricks. The refractory materials produced by SNR company have been exported to more than 35 countries such as America, Germany, France, Spain, Italy, Japan, Korea, etc. The main products include Silica Brick, High Alumina Brick, Tank Bottom Fireclay Block, Sillimanite Brick, Corundum Brick, Zircon Brick, Mullite Brick, Magnesia Brick, Insulating Bricks,Silica Carbon Bricks,Magenisea Carbon Brick, refractory castables and refractory mortar of related materials.Any demands ,please don't hesitate contact with us.
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