[China Glass Net] The main purpose of glass melting furnace cold modification is to increase melting capacity, improve melting quality, save energy and reduce consumption, and extend kiln age. There are a number of corresponding transformation measures for each transformation purpose. Some of the transformation measures can only improve one of the economic and technical indicators of the furnace, and some of the transformation measures can improve the various indicators of the furnace.
When the glass melting furnace is operated to the later stage of the kiln age, the kiln body often suffers from the weakening of the local structure. When it runs again, there may be a large area collapse; or the energy consumption increases, the product quality deteriorates, and the operating efficiency decreases. Happening. Before such a situation arises, it is necessary to prepare for the cold repair of the melting furnace.
Under normal circumstances, the kiln should be placed with glass water, and then the old kiln should be demolished to build a new kiln, that is, the glass furnace should be “cold repairedâ€; there is also a case of “hot repair†of the furnace, which is usually in the kiln body. If the damage is broken and the rest of the parts are still in good condition, the production should be stopped or reduced during the short period of heat repair, and the furnace should be insulated and resumed immediately after the heat repair.
The glass melting furnace is a large-scale, small-volume, non-type thermal equipment. It is rarely rebuilt according to the original drawings during cold repair. It is often more or less necessary to carry out some technical transformations, and some have to undergo major renovations. . The purpose of the transformation is: 1 increase the melting capacity, 2 improve the melting quality, 3 save energy consumption, 4 extend the kiln age, and so on.
According to different transformation purposes, there may be different modification measures. Some transformation measures can only improve one economic and technical index of the melting furnace. Some transformation measures can improve many indexes of the melting furnace, for example, reasonable design. The size of the kiln, the use of high calorific value fuels and high-performance spray guns, and the ordering of high-quality refractory materials, etc., are beneficial to the glass melting furnace to increase the melting capacity, improve the melting quality, save energy and reduce consumption, and the length of the kiln.
one. Measures to increase the melting capacity of glass melting furnace
According to the operating experience of float glass furnaces at home and abroad, the main measures for increasing the melting capacity of float glass furnaces can be summarized as: kiln size, fuel and spray gun, refractory material, full kiln width feeding, plus Large pre-melting zone, increased flame coverage, increased number of spray guns, increased melting temperature, electric fluxing, etc.
1. The main process of the kiln shape is reasonable: the main process size of the kiln shape should match the melting capacity, especially the pool width, the length of the pool and the ratio of the length of the pool to the width of the pool in the melting and melting zones are critical. When the melting capacity is too large, it affects both the melting quality and the energy saving.
2. High calorific value fuel and high efficiency spray gun: To improve the melting capacity of the glass melting furnace, high calorific value fuel and high efficiency spray gun are needed to achieve the desired high temperature melting effect in the melting zone. The melting temperature is the melting capacity of the glass melting furnace. The decisive role, high calorific value fuels include: heavy oil, liquefied petroleum gas (LPG), natural gas and so on. There are two types of spray gun installations for glass melting furnaces: 1 spray gun ignited in a small furnace, including top-insertion, side-insertion, and bottom-insertion; 2 spray guns ignited outside the small furnace, which is a furnace type. At present, most glass melting furnaces in China use the furnace type spray gun, which is convenient for maintenance and replacement. In comparison, the spray gun ignited in the small furnace is more efficient than the spray gun fired outside the small furnace, but the investment is large, and the maintenance and replacement is not convenient.
3. Full kiln wide feeding technology: In the past, the narrowing feeding port corresponding to the width of the melting section is about 80%. Since the width of the cloth hopper (commonly known as ç°¸è) of the feeder is narrower than the feeding tank, the batching material is in the kiln. The distribution width inside is also about 70% of the kiln width, so that the narrow strip enters the kiln. It is obvious that the flame in the kiln does not make good use of the heating area of ​​the batch. With the full kiln wide feeding tank, the distribution width of the batch material in the kiln can reach about 90% of the width of the melting section, and the heating area of ​​the kiln flame to the batch material is fully utilized, which melts the melting furnace. The ability and the quality of the molten glass are quite high. The use of a full kiln wide feed tank can increase the melting capacity by about 8 to 10% compared to the use of a narrow feed tank.
4. Increasing the length of the pre-melting zone: the length of the pre-melting zone is generally the size of the center line of the small furnace to the front end of the melting section, and the actual pre-melting zone also includes the portion below the nose zone of the L-shaped hanging wall. The glass batch entering the kiln is heated by a long pre-melting zone, which is advantageous for improving the melting ability.
5. Increasing flame coverage: Flame coverage is defined as the percentage of the total width of the kiln's small furnace blast opening as a percentage of the length of the melting zone. The greater the flame coverage, the more uniform the flame distribution in the kiln, and the more favorable the melting effect, the better the melting capacity of the furnace.
6. Increasing the number of spray guns: The operation results of many domestic melting furnaces show that when two guns are arranged in the small furnace, the flame distribution in the kiln is not uniform: when multiple guns are used above three guns, the flame distribution in the kiln is evenly distributed. Sex has improved a lot. The uniform distribution of the flame in the kiln is equivalent to an increase in the flame coverage, which is beneficial to the melting effect and can improve the melting ability of the melting furnace.
7. Increasing the melting temperature: High-temperature melting is very effective for improving the melting ability. The high-temperature melting means that the temperature system takes a higher temperature curve before the hot spot in the melting zone, and the hot spot temperature should reach 1590 ° C or higher. This is done in the case of the structural conditions of the furnace (including the reasonable size of the kiln, the use of high calorific value fuels and high-performance spray guns, and excellent refractory properties).
According to the data, the temperature of the chest wall in the melting section of the former Soviet Union is increased by 10%, and the average unit temperature is increased by 4%. There is also a saying that the melting temperature is increased from 1560 ° C to 1600 ° C, which can increase the glass furnace output by 12% to 15%. Based on these data, it can be roughly considered that the melting capacity can be increased by 3% to 4% for every 10 ° C increase in the melting temperature.
8. Electric Flux: Foreign merchants (FIC, UK) that provide electric fluxing equipment have made it clear that electric fluxing can increase the melting capacity by about 10%. For the furnace of the new float line, as long as there is no such limitation as the narrow space, it is not necessary to power on the melting equipment from the beginning. It is often the case that after the melting furnace is put into production, it is found that the melting assist is considered when the melting ability is insufficient.
two. Measures to improve the quality of molten glass
For the structure of the float glass furnace itself, the main measures to improve the melting quality of the molten glass can be summarized as: kiln size, fuel and spray gun, refractory material, large clarification area, bottom decking, mixing facilities, blocking facilities, space separation , kiln pressure is stable, temperature is constant, etc., such measures.
1. The main process of the kiln shape is reasonable: the main process size of the kiln shape matching the melting capacity, especially the pool width of the melting part and the melting zone, the length of the pool and the ratio of the length of the pool to the width of the pool are also critical to the quality of the melt. Large or small will have an adverse effect on the quality of the molten glass.
2. High calorific value fuel and high efficiency spray gun: To melt high quality float glass, high calorific value fuel and high efficiency spray gun must be used to achieve the desired high temperature melting effect in the melting zone, melting temperature and melting of the glass melting furnace. The quality of the slope liquid plays a decisive role.
3. The refractory materials in all parts of the melting furnace are properly arranged and the quality is guaranteed: the refractory material that contacts the glass liquid part and may fall into the glass liquid has a great influence on the quality of the glass liquid. The key part is the small furnace squirting port and the cooling part after the hot spot. The bottom of the pool, the wall of the pool and the outlet of the cooling section should be made of bricks with excellent erosion resistance. The refractory materials of all parts of the furnace should be properly arranged and guaranteed.
4. Longer clarification zone: The glass solution just formed in the melting zone contains many bubbles and ash bubbles (small bubbles) to be discharged in the clarification zone: at the same time, the chemical composition and temperature, density and viscosity of the newly formed glass solution are not The same, very uneven, must be homogenized. There is a clarification zone longer than the hinge to allow more bubbles to escape and the homogenization of the molten glass is more pronounced.
The bottom of the kiln pool: the flow of glass at the bottom of the kiln (usually opposite to the surface flow) will flush the bottom of the pool, and the refractory powder of the bottom of the pool will be washed into the glass, and It is not easy to be melted, which is one of the important reasons for the melting defects of the molten glass. The refractory material with good erosion resistance can solve this problem better.
6. Glass liquid stirring device: Stirring can significantly improve the uniformity of the glass liquid, and reduce the glass defects caused by the chemical composition, temperature, density, viscosity and the like of the glass liquid. Common agitation devices include horizontal agitators and vertical agitators. In comparison, horizontal agitators are simple and durable, while vertical agitators provide better agitation.
7. Glass liquid surface floating material blocking device: In the glass melting furnace, some floating objects sometimes appear on the surface of the molten glass. These floating objects mainly come from two reasons: one is the unmelted glass batch material residue; the other is the furnace in the furnace operation. Refractory particles or fragments that are peeled off or dropped on the body structure. A large water bag is placed at the neck of the float glass melting furnace, one of which is to intercept the floating surface of the glass liquid.
8. The upper space separating device between the melting portion and the cooling portion: due to the influence of the commutation or the like, the temperature, the kiln pressure, the atmosphere, etc. in the melting portion have a certain periodic influence on the cooling portion, which is very good for producing high-quality float glass Not working. The function of the neck hanging wall is to separate the upper part of the melting part and the cooling part to a large extent, and the separation effect of the neck hanging wall is as strong as possible.
9. Kiln pressure adjusting device for cooling section: In order to stabilize the production of float glass, the kiln pressure in the cooling section is required to be slightly higher than the kiln pressure of the melting section, and is adjustable. The fine-tuning air system of the cooling section is mainly used to adjust the kiln pressure of the cooling section.
10. The temperature adjustment device of the cooling part: the temperature of the cooling part can be kept constant, which is very important for producing high-quality float glass, especially the temperature of the glass liquid at the end outlet of the cooling part, and the small fluctuation will produce a great effect on the intrinsic quality of the glass. Significant influence, many foreign glass melting furnaces are equipped with temperature regulating devices in the cooling section, mostly using wind or water cooling devices, but also using heating and heating measures.
11. High temperature melting: High temperature melting is very effective for improving the melting quality of molten glass. High temperature melting means that the temperature system should take a higher temperature curve before the hot spot in the melting zone, and the hot spot temperature should reach 1590 ° C or higher.
12. Preventing the viscous edge of the eccentric material: the phenomenon of viscous material eccentricity is relatively easy to occur in the operation of the glass melting furnace. It is difficult to melt the glazed glass raw material residue after reaching the hot spot. To seriously affect the quality of the glass, various feasible measures must be taken. Prevents skewing of the adhesive edges and prevents unrefined raw material residues from appearing after hot spots for various reasons.
In addition, there are some measures such as bubbling, kiln, electric fluxing, etc., which have certain effects on the melting quality of some small tonnage furnaces or special glass furnaces. The float glass melting furnace has large tonnage and strong inertia. The use of bubbling, kiln, electric fluxing and other measures can not improve the melting quality, and it may bring some hidden dangers.
three. Energy saving measures
For the structure of the float glass furnace, the main measures for energy saving can be summarized as: kiln size, fuel and combustion, flame height, full kiln width feeding, kiln insulation, kiln sealing, lattice configuration, shallow Pool, narrow card neck, operating system and other measures.
1. Kiln size: The main process size of the kiln shape should be designed reasonably. The main process size of the kiln shape matching the melting capacity, especially the length and width dimensions and the length and width ratio of the melting part and the melting zone are reasonable and preferable. . When this value is achieved, not only the melting capacity and the melting quality of the melting furnace are ensured, but also the energy consumption is low. The main reason for the high energy consumption of many glass melting furnaces in China is that the length of the melting zone is too large, the flame in the kiln is dispersed, and the heat flux density is low, which does not reach the melting temperature.
2. Fuel and Combustion: Using high calorific value fuels and high-performance guns to achieve the desired high temperature melting in the melt zone. Select the appropriate fuel and air ratio so that the flame length is 3/4 of the kiln width; accurately adjust the spray gun to achieve a proper fuel supply angle and flow rate; achieve automatic adjustment of the combustion process; adjust the fire change time to a smaller limit; Continuous control of smoke composition is the basic condition for energy saving in glass melting furnaces.
3. Flame height: The height between the flame in the kiln and the liquid level of the glass should be minimized. The flame sprayed into the kiln from the small furnace blasting port should not interfere with the glass surface and should be as close as possible to the glass surface. Many foreign furnaces use the "top insert, side insert, bottom insert" type spray gun. The upper part of the fire exit port is a small furnace bunker brick. The top of the small furnace top is about 500mm higher than the top of the pool wall (between 470 and 580mm). ), the combustion air is tilted down in the small furnace and the fuel meets and then burns to form a flame into the kiln. The flame adheres to the glass surface without disturbing the liquid surface, and the thermal efficiency is relatively high.
At present, the glass melting furnace designed by the country basically adopts the down-type spray gun. The nozzle metal for the spray gun is to be set between the fire-breathing hook brick and the small furnace tongue. The height of the nozzle brick is generally 200mm. The kneading surface is about 700 mm higher (between 670 and 780 mm) than the top of the pool wall. The height between the flame and the liquid level of the glass is increased by 200mm. Obviously, this keeps the flame away from the liquid surface of the glass, reducing the thermal efficiency of the flame, which is about 3 to 5% lower. The top of the small furnace is higher than the top of the pool. The more the flame is produced, the lower the thermal efficiency.
4. Full kiln wide feeding technology: The energy saving effect produced by the whole kiln wide feeding technology can be said from two aspects: one is that in the melting process, the full kiln wide feeding tank is put into the kiln to make the mixing belt wider and more The thinness increases the heated surface area and heat permeability of the batch material, so that the heat in the melting zone is absorbed more quickly and faster by the batch material, thereby reducing the loss of heat to the outside of the kiln. Secondly, in the structure of the melting furnace, the full kiln wide feeding tank can make the pool width and the pool length of the melting portion slightly smaller, which reduces the surface heat loss of the entire kiln body, thereby generating energy saving effect.
5. Kiln insulation: The insulation of the kiln is very clear to the energy saving effect of the melting furnace. The key parts that need to be insulated include: the large part of the melting part, the chest wall, the pool wall, the bottom of the pool, the bottom plate of the small furnace, the side wall, and the top The upper wall of the regenerator, the top raft, the wall of the flue and the raft.
6. Kiln body seal: The sealing effect of the kiln body on the energy saving of the melting furnace is clear. The key parts of the melting furnace that need to be sealed include: the bottom of the brick wall of the nose wall of the feeding wall, the bottom edge of the brick wall, and the top of the pool wall of the melting part. Between the hook bricks, the large expansion joints of each section, the expansion joint of the small furnace, the wall between the regenerator and the lame, the expansion joints of the various sections of the regenerator, and various operating doors, holes, holes, etc. Seal at any time.
7. Lattice configuration: the combustion temperature of the fuel in the glass melting furnace is proportional to the preheating temperature of the combustion air. The preheating temperature of the combustion air has a great relationship with the rationality of the lattice configuration. Whether the lattice configuration is reasonable or not is mainly reflected in The lattice heat storage area and the lattice height. If the lattice structure is reasonable, the preheating temperature of the combustion air can be increased, and the combustion temperature of the fuel is increased, thereby generating an energy saving effect.
Decreasing the temperature of the exhausted flue gas will also have a significant effect on the energy saving of the glass melting furnace. At present, the temperature of the flue gas discharged from the regenerator of the glass melting furnace is generally around 600 ° C. If it can be lowered to 200-300 ° C, it will be More than 10% energy saving, to do this is the need to do development and research work.
According to the information: increasing the preheating air preheating temperature can greatly reduce the fuel consumption. If the temperature of the combustion air is raised to 1000 °C, if the temperature is raised to 1100 °C, the fuel can be saved by 8%. By 1200 ° C, you can save 15% of fuel. According to this information, it can be roughly considered that for every 100 °C increase in the preheating air temperature, fuel can be saved by 7% to 8%.
8. Shallow pool structure: The glass bath is a large heat sink. For a glass furnace with a certain plane size, the pool depth is different. The larger the pool depth, the larger the total heat dissipation. The bigger it is. In the past, the deep melting pool of the glass melting zone was 1400-1500 mm deep, and now it is mostly shallow pool of about 1200 mm, and the depth of the cooling section can be about 900 mm. The shallow pool structure has a certain energy-saving effect.
9. Narrow card neck: It can be seen from the longitudinal section of the glass flow in the melting furnace that the flow direction of the glass flow is different at different depths of the neck, and the upper layer close to the glass surface flows to the cooling part, close to the bottom of the pool. The lower layer flows back to the melt. The temperature of the molten glass flowing to the cooling portion is lowered, and after being returned to the melting portion, it is again subjected to secondary heating, which consumes heat, and the neck narrowing can reduce the fuel consumed by the secondary heating.
10. Temperature system: The melting rate of glass batch materials is closely related to the temperature system in the kiln. The high temperature operation system can accelerate the melting of glass batch materials and produce glass liquid, which has obvious energy saving effect.
four. Extending kiln age measures
From the structure of the float glass furnace, the main measures for extending the kiln age can be summarized as: refractory material, furnace steel structure, expansion joint, L-shaped hanging wall, kiln pressure, air cooling, water cooling, furnace masonry , barbecue kiln, maintenance and other measures.
1. Refractory: The quality of refractory materials in all parts of the furnace must be ensured. The refractory materials in different parts should be matched properly. The parts that need to be separated by acid and alkali must be separated by reliable materials. The refractory materials in contact with the glass must be resistant to glass liquid corrosion. Resistant to erosion, in the middle and upper sections of the regenerator, the material should be resistant to high temperature and alkali dust.
2. Furnace steel structure: For example, a 500t/d float glass melting furnace is made up of nearly 20 different types of refractory materials, more than 300 sizes, hundreds of thousands (500,000 to 700,000 pieces), and total weight. Thousands of tons (5,000 to 8,000 tons) of refractory materials are built. The melting furnace steel structure is used to support and restrain the masonry kiln brick structure. The melting furnace steel structure must ensure that the brick structure of each part of the kiln body can be maintained from the beginning of the masonry to the high temperature operation. Does not produce more than the allowed deformation or crush the brick. Therefore, the steel structural parts of various parts of the melting furnace cannot be weak or strong.
3. Expansion joint: The kiln structure of the glass melting furnace should be operated at high temperature for a long time, and the expansion joint of each part of the kiln body has a great influence on the kiln age. The refractory material has thermal expansion. To ensure the safety of the kiln structure, suitable expansion joints must be left for some kiln structures subject to expansion restrictions to ensure that the refractory bricks are not crushed at high temperatures and the kiln walls are not deformed.
4. L-shaped hanging wall: In the past, the front wall of the glass melting furnace was generally made of silica brick. The span of the fish belly is generally smaller than that of the fish. The calculated compressive stress of the fish belly is relatively large; the silicon brick of the fish belly is acidic, and it must withstand the chemical attack of the alkali vapor in the batch; Heat scouring and erosion with high temperature. The fish belly is in such a harsh working condition, and its safety and reliability are very poor. It used to be one of the weaker links affecting the life of the glass melting furnace. The L-shaped hanging wall structure was developed for the short life of the fish belly. With the application of the L-shaped hanging wall structure on the front surface of the glass melting furnace, the safety and reliability of the front wall structure of the melting furnace has been well solved.
5. Kiln pressure: Generally speaking, the kiln pressure in the melting section is 5 to 7 Pa, which means that the pressure in the kiln is 5 to 7 Pa higher than the pressure outside the kiln. The micro-positive pressure in the kiln is to ensure that the cold air outside the kiln is less likely to enter the kiln, and that the kiln is less likely to wear fire outside the kiln. The greater the kiln pressure, the easier it is to wear fire outside the kiln, so that some small gaps should not be worn. Because of the fire, a large seam is formed, which is commonly called “burning through†and burns through. It will have an impact on the structural life of the kiln.
6. Air-cooled, water-cooled: The place where the blower cooling is required on the glass melting furnace mainly includes: the pool wall on both sides of the melting part, the pool wall on both sides of the neck, the foot beam in the melting zone, the iron gate of the feeding port, and the L-shaped hanging wall. The places where water cooling is required mainly include: the outer corner of the pool wall at the entrance of the card neck, and the outer corner of the pool wall where the liquid level pool and the melting portion meet.
7. Melting masonry: The masonry quality of glass melting furnace plays a big role in the life of the melting furnace. It is necessary to choose a qualified professional construction unit, the construction equipment should be complete, the types of work should be matched, the quality supervision should be indispensable, and all parts of the glass melting furnace should be There are detailed masonry requirements that must be guaranteed.
8. Roasting kiln heating: The heating of the kiln is crucial to the operating life of the glass melting furnace, which will irreversibly affect the performance and life of the subsequent melting furnace. For example, due to improper kiln kiln deformation, cracking, sinking, crushing, etc., must affect the kiln age. The heating curve of the kiln must be reasonable. The parts that need to control the expansion during temperature rise must be operated in time and accurately, and strictly controlled.
9. Reasonable operation: The temperature system of the glass melting furnace should be reasonable, the kiln pressure of each part should be reasonable and stable, the fluctuation of the liquid surface should be small, the various facilities are in good condition and the operation is accurate, and the damage to the kiln body during operation is not generated.
10. Maintenance: The kiln body inspection work should be done daily according to the operating rules of the glass melting furnace, and problems should be maintained in time. In the middle and later stages of the furnace operation, maintenance work should be strengthened.
Fives. Conclusion
The above are some conventional measures taken to increase the melting capacity, improve the melting quality, save energy and reduce the kiln age when the float glass melting furnace is cold modified. With the advancement of thermal technology, rich experience in furnace design, and development of new refractory materials, more and better new glass melting furnace technologies will be developed, which will melt the melting capacity and melting quality of glass melting furnaces. New application results have been achieved in terms of energy saving and long kiln age.
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