Above the glass surface, the entire flame-filled furnace space surrounded by the front wall (L hanging wall), the parapet, the large chute and the back gable is called the melting part superstructure, also called the flame space. This space is not only a flame burning space, but also a heat transfer space where the flame gas transfers its own heat to the glass liquid, the breast wall and the large chrysalis.
The size of the flame space is related to the scale of the kiln, the type of fuel, and the amount of fuel consumption. The greater the amount of melting, the greater the total fuel consumption, the greater the space required for combustion, and the greater the size of the flame space. When heavy oil is used as fuel, because the combustion of heavy oil in the kiln is different from the combustion of coal gas, the processes of atomization, evaporation of oil droplets, thermal decomposition, diffusion, mixing and combustion are all carried out in the flame space. There must be sufficient combustion space to ensure complete combustion of the oil mist. So from the perspective of combustion, the flame space of oil-fired kilns is slightly larger than that of gas-fired kilns. For melting furnaces that also use heavy oil, the form of inserting heavy oil spray guns on the surface of the pool wall is adopted. Since the nozzle bricks raise the burner nozzle of the small furnace, the combustion space is larger than that of inserting heavy oil spray guns at the bottom of the small furnace or the top of the small furnace. In the form of space. However, from the perspective of energy saving, it is better to use a small furnace bottom kang or small furnace top to insert a heavy oil spray gun than a flat surface insert on the pool wall.
Generally, the width of the flame space is wider than that of the kiln, and each side is wider than 250~300mm. Because the inner side of the kiln bricks is eroded soon after the furnace is put into production, it is easy to be damaged. In order to protect the parapet wall and prevent the iron parts from burning, the parapet wall is laid out.
The height of the flame space is equal to the height of the parapet wall to increase the trellis strands. The size of the flame space must meet the space required for fuel combustion. Therefore, the height of the flame space mainly determines the type and amount of fuel used in the furnace. At the same time, it is necessary to consider reducing the external heat dissipation of the furnace and the stability of the furnace. The height of the parapet wall is increased after the gas is changed to fuel oil, and the small furnace is changed to the plug-in type, but the flame space should not be too high, otherwise it will increase the heat dissipation of the kiln body and increase the useless space in the kiln body to make the flame It is soft and floating, which is not conducive to heat transfer in the kiln. Therefore, generally under the premise of ensuring the cross-sectional area of ??the nozzle and the stability of the large turret, the height of the flame space tends to be lowered to facilitate the heat transfer of the flame and the large turret to the batch material and the molten glass and reduce the heat dissipation loss of the kiln body to the outside. .
(1) Front wall structure
The front wall or L hanging wall is the front end wall of the flame space of the melting part. It forms the front space of the melting part together with the large chute, and its main function is to block the hot air ejection at the front end of the melting furnace to save fuel; Reduce the heat radiation of high temperature to the feeder and kiln head silo.
Nowadays, L suspended walls are often used as the front wall. The L suspended wall has a reasonable structure and does not require thermal repair, and the thermal strength is much better than that of the front wall whose main structure is arched and flat suspended walls.
The L suspended wall is composed of two upper and lower steel structures [as shown in Figure 1(a) and (b)] and a brick structure. The lower structure (usually called the nose area) has 45°, 30° and 60° (nose area) The angle between the inclined plane and the horizontal plane) is a variety of forms, commonly used is a 45° air-cooled suspended column suspended wall. The nose area of ??the L hanging wall (as shown in Figure 2) uses 33# oxidation method non-shrinkage fused zirconia corundum bricks and sintered zirconium mullite backing bricks composite zirconium composite bricks (as shown in Figure 3) Due to the low temperature at the lower end, sintered zirconium corundum bricks are still used; high-quality silica bricks are used in the straight areas, and the junction between zirconium composite bricks and high-quality silica bricks uses a layer of sintered zircon bricks for transition. Various brick materials are passing When the special hooks are hung on the heat-resistant steel castings, they are all built with refractory mud. During production, the cooling air enters the inflatable box truss and is diverted to several vertical air column pipes. The heat-resistant steel casting claws also Fastened to the pipe, the airflow directly cools the claw hooks. During normal production, the air pressure in the cavity composed of the suspended wall steel structure and the brick structure is required to be higher than the furnace pressure by 40~60Pa, and the temperature shall not be higher than 110°C. The limit instantaneous temperature does not exceed 160°C. In order to facilitate the control of wind pressure and temperature, a fan is usually used alone for adjustment.
(a) h hanging wall steel structure front; (b) L hanging wall steel structure back
The short wall at the junction between the upper part of the feeding pool and the breast wall of the melting part on both sides of the nose area of ??the L hanging wall is called the wing wall. The wing wall is usually made of 33# oxidation method ordinary cast fused zirconia corundum bricks and high-purity crack-resistant zircon stone bricks. Masonry, its main function is to make up for the places where the hanging wall cannot be sealed; the top of the L hanging wall and the junction of the melting part are sealed with high-quality silica bricks; the outside of the hanging wall is insulated with calcium silicate board, and then 1.5~3mm thick The galvanized sheet is used as the shield seal.
Figure 2L suspended wall photos Figure 3L suspended wall lower nose area composite brick structure sealing.
Since the lower part of the L hanging wall cannot completely block the flame in the kiln, the front face water bag or hanging wall is used to seal the part close to the batch in the nose area of ??the L hanging wall.
(2) Parapet structure
The breast wall is supported on the I-steel columns on both sides of the melting furnace, and is mainly composed of chin palm iron, breast wall pallets, hook bricks, and breast wall bricks. The parapet wall needs to ensure sufficient structural strength at high temperatures. The hook brick is the key part. Its function is to protect iron parts such as the parapet pallet and the chin palm iron. Some furnace hook bricks themselves consist of lower gap bricks and small bricks. protection. The breast wall of the melting part is usually built with zirconium corundum bricks, the breast wall of the clarification part and the cooling part are generally built with silica bricks, and the junction of zirconium corundum bricks and silica bricks is made of zircon bricks. The thickness of the breast wall is generally 400~500mm, mainly to reduce heat loss.
The height of the parapet and the large slabs together constitute the height of the flame space. Therefore, the height of the breast wall is also related to the size of the flame space and the amount of heat dissipation from the kiln body. The height of the breast wall varies according to the fuel used and the height of the nozzle of the small furnace adapted to it. The height of the breast wall of the general float glass production line is 1400~1700mm.
The force transmission path of the parapet wall:
Breast wall weight → hook brick → breast wall support plate → chin palm iron → steel column-kiln bottom secondary beam → kiln bottom main beam → kiln bottom concrete column.
The breast wall of the melting part adopts 30mm thick zirconium sealing material and 65mm thick lightweight high-alumina bricks from the inside to the outside for cold insulation; the breast wall of the clarification part adopts 80~140mm thick light insulation paint for thermal insulation from the inside to the outside.
(3) The structure
Like the breast wall, the big chute is also supported on the I-steel columns on both sides of the furnace, and it is mainly composed of steel chute, side chute brick, big chute brick and brace. Since the melting part is in the high temperature area of ??the entire kiln, in order to ensure the safety of the steel ballast in the melting part, air-cooled cooling should be adopted for the steel ballast in the melting part, and the steel ballast in the clarification part is not cooled.
The function of the big chute: It forms a flame burning space with the parapet, and can also be used as a medium for the flame to radiate heat to the batch and glass liquid, that is, absorb the heat when the fuel burns, and then radiate to the liquid surface. From the point of view of radiation and heat dissipation, the closer to the liquid surface, the more radiant heat is reflected to the glass, and the less heat dissipation. Therefore, the main way to reduce the size is as low as possible while ensuring the strength of the structure. It is to make the strands smaller.
Material selection of large turban bricks: Because the large turban in the melting part is subjected to high temperature, all the large turbans used for air combustion are made of high-quality high-quality silica bricks with high temperature resistance (the melting window for full oxygen combustion is 33# zirconium corundum brick or α-β corundum brick ). The length of large slab bricks is generally 350mm, 450mm for slabs with a span of more than 10m, and 500mm for special load-bearing slabs. The masonry is divided into several sections, each independent, and there is an expansion joint between the two sections to adapt to the expansion performance of the
silica brick during the ignition and baking kiln. During cold repair, the most severely burned section or two sections can be removed without having to renew all of the large dams. The quality requirements are strict during masonry, and the mud joints should be small. The inner surface form of the large silica brick can be flat or honeycomb. The heat radiation rate of the honeycomb ballast is 15% higher than that of the flat type. However, the production cost of honeycomb silicon bricks is relatively high, so it is currently used less.
Strand and span: From a thermal point of view, it is beneficial to have a lower size of the sill. The heat radiation can be distributed evenly along the entire transverse plane as much as possible, and the more radiant energy reflected to the glass liquid. There are two ways to reduce the large arches: one is to reduce the height of the parapet, and the other is to reduce the arches. However, there is a limit to reducing the height of the parapet, and the structural strength of the kiln should also be considered to reduce the trellis. Because the kiln has a horizontal thrust, the force will be greater at high temperatures. If the tie is too loose or too tight or the tension is different, the structure of the kiln will loosen, and the top of the kiln will crack or sink. The smaller the roller, the greater the horizontal thrust. Therefore, the strands can only be minimized under the premise of ensuring sufficient structural strength, steel structure function and a certain flame space.
The way of force transmission of the big scorpion:
The weight of the large ballast→steel ballast→the upper slap iron→steel column→the secondary beam at the kiln bottom→the main beam at the kiln bottom→the concrete column at the kiln bottom.
The foot of the steel upright column on both sides of the tower is fixed on the secondary beam, and the column head is tightened by the brace across the top of the tower to bear the horizontal thrust of the tower.
The breast wall, the big chute, and the kiln pool are divided into three independent supporting parts, and finally the load is transmitted to the steel structure of the kiln bottom. The breast wall of the melting part and the big chrysanthemum are sealed with edge bricks (previously used gap bricks), and the clarification part’s parapet wall and the big chrysalis are sealed with gap bricks to protect the big chrysalis and steel ballast from flames. Radiant heat burns. The lower gap brick protects the hook bricks between the breast wall of some melting furnaces and the kiln pool, and a row of electrofusion head protection bricks are placed on the lower gap bricks to protect the hook bricks and iron parts.
Insulation of the big ring: Because the big ring is the main heat dissipation part of the furnace, in order to save energy and reduce consumption, it is necessary to carry out the necessary heat preservation of the big ring. Because of the difference in the degree of knowledge of insulation materials and insulation technology, various companies adopt different insulation procedures. The typical method is: after cleaning the outer surface of the big chute, pour a layer of 5mm thick siliceous slurry on it in turn to ensure that the brick surface is completely sealed → wipe 30-50mm thick siliceous sealant → dry lay-up 2~ 3 layers of 65mm-thick lightweight silica brick→apply 50~60mm siliceous plastic→apply 80~100mm light-weight thermal insulation coating→apply 40~50mm thick light-weight high-strength thermal insulation coating as a protective layer.
The use of heat preservation can not only greatly reduce the surface temperature of the slab, reduce heat dissipation and save energy, but also reduce the temperature gradient between the inside and the outside of the slab, increase the temperature of the inner surface of the brick, and enhance the effect of the slab on the glass liquid. The heat transfer makes the batch materials melt faster, clarify better and the glass quality is higher.
(4) Anti-snake structure
The reverse structure is mainly used in the furnace that burns producer gas. In the plate glass melting furnace that burns producer gas, the connection part between the small furnace nozzle and the large chute adopts a reverse chute structure.
The function of the anti-chamber is to transfer the weight of the large cupboard on the nozzle of the small furnace to the large cupboard on both sides of the nozzle through the vertical to the direction of the large cupboard, and then be borne by the columns on both sides of the furnace. This structure can greatly reduce the height of the breast wall of the horizontal flame kiln and reduce the heat loss. If the inverted turret structure is not used, the small furnace spout is inserted under the large turret, resulting in a higher breast wall and a large heat dissipation area. Since there are no iron parts at the connection part of the spout and the big chute, the anti-chute structure has no danger of damage to the steel structure.
Anti-spots and stilts are also part of the large stilts. There are no expansion cracks at the counter and ballast, and the masonry quality is very strict. The bricks need to be pre-processed and numbered in advance to ensure sufficient structural strength and tightness. The anti-drapery is built with high-quality silica bricks like the large-supplemented bricks. The anti-draped bricks should be masonry with four sides (and six sides) with large and small heads, which not only satisfies the arc in the direction of the large channel, but also satisfies the anti-drapery. The arc of the direction. With the same width of the spout, the span of the ballast is larger, and the ballast is protected by the small stacks and is not easy to burn. However, the span is too large and the structural strength is reduced. This structure limits the increase in the width of the ejection port.
(5) Back gable
The back gable is a wall at the end of the melting part, which is directly built on the low trellis (also known as the load-bearing trellis). Mainly play a role of separating airflow and sealing. Except for the observation hole and the camera hole, the wall is made of crack-resistant zircon bricks, and the other parts are all made of high-quality silica bricks. Some production lines use double "J"-shaped hanging walls or "U"-shaped hanging walls to replace the ordinary back gables at the melting and cooling sections, which can effectively seal the airflow. However, this type of structure is complex and requires relatively high investment. Big.
