Method for improving quality of photovoltaic rolled glass
By controlling the temperature and pressure difference between the branch passage and the overflow port, the problem of glass melt quality degradation at the edge of the branch passage in photovoltaic rolled glass was solved, achieving thermal and chemical uniformity of the glass melt and improving the quality of photovoltaic rolled glass.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA LUOYANG FLOAT GLASS GROUP
- Filing Date
- 2026-03-09
- Publication Date
- 2026-05-05
AI Technical Summary
In the production of photovoltaic rolled glass, the thermal and chemical inhomogeneities caused by the contact between the molten glass at the edge of the branch channel and the refractory material of the pool wall lead to a decline in the quality of the molten glass, especially the introduction of bubbles and stone defects.
By controlling the amount of pull per unit cross-sectional area of the branch passage, and by using the branch passage edge temperature regulation system and the overflow outlet temperature and pressure regulation system, the lateral temperature difference between the edge and middle of the branch passage and the lateral temperature difference between the edge and middle of the overflow outlet are adjusted respectively, and the positive pressure in the branch passage is controlled, thereby reducing the number of bubbles and stones in the molten glass.
It effectively reduces the number of bubbles and stones in photovoltaic rolled glass, improves the thickness uniformity of the glass sheet, and enhances the overall quality of photovoltaic rolled glass.
Smart Images
Figure CN121974545A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to glass manufacturing technology, specifically a method for improving the quality of photovoltaic rolled glass. Background Technology
[0002] Photovoltaic rolled glass is a type of flat glass. It is named rolled glass because it is formed by pressing and stretching between the upper and lower rollers of a rolling mill. It is used as cover and back sheet for photovoltaic cell modules.
[0003] In current photovoltaic rolled glass production, due to the need for energy conservation and emission reduction, the scale of melting furnaces is becoming increasingly large, generally exceeding 1000T / D. A single forming line cannot handle the volume of molten glass produced by a large melting furnace, so the forming section needs to be divided into multiple branches to form the molten glass and manufacture photovoltaic glass products.
[0004] This method of dividing the glass into multiple branches is usually implemented using branch passages. The molten glass enters the neck from the melting section, then enters the transverse passage, and then enters the branch passage. Each branch passage outlet is connected to a rolling mill for forming.
[0005] While this method successfully diverts and shapes molten glass from large-tonnage furnaces, it is limited by the fact that the rolling rolls cannot be expanded indefinitely. Therefore, the width of the corresponding branch passages is also limited, mostly below 4.5m.
[0006] The increasing size of melting furnaces and the limited width of branch passages result in large drawing volumes and high glass flow rates in individual branch passages. Consequently, a significant portion of the glass flowing at the edges of each branch passage, which is in contact with the refractory material, enters the forming flow. Because the glass at the edges is in contact with the refractory material of the furnace wall, its thermal and chemical uniformity differs from that of the mainstream glass. Furthermore, it is prone to containing defects such as bubbles and stones, which, when mixed with the mainstream glass, leads to a decline in the overall quality of the glass. Summary of the Invention
[0007] In response to the problems raised in the background art, the purpose of this invention is to propose a method for improving the quality of photovoltaic rolled glass, aiming to solve the problem of quality degradation of photovoltaic rolled glass caused by molten glass at the edge of the branch channel.
[0008] To achieve the above objectives, the present invention adopts the following technical solution: A method for improving the quality of photovoltaic rolled glass includes: when molten glass flows through a branch passage in a melting furnace, controlling the amount of pull per unit cross-sectional area of the branch passage, and using a branch passage edge temperature regulation system to reduce the temperature at the edge of the branch passage, controlling the lateral temperature difference δ1 between the edge and the middle of the branch passage to be 50℃-60℃; when molten glass flows out from the overflow port, using an overflow port temperature and pressure regulation system to reduce the lateral temperature difference δ2 between the edge and the middle of the overflow port, and controlling the atmospheric pressure in the branch passage to be positive. The overflow outlet temperature and pressure regulation system includes a flame deflector brick device, a temperature detection device, and a pressure detection device. The flame deflector brick device includes multiple flame deflector bricks arranged side by side above the overflow outlet. Each flame deflector brick is connected to a lifting mechanism on its upper part. The lifting mechanism adjusts the lateral temperature difference of the molten glass at the overflow outlet and the atmospheric pressure in the branch passage by adjusting the opening of the flame deflector bricks.
[0009] The pulling amount per unit cross-sectional area of the branch path is controlled by the following method, as follows: When the total pull amount of the branch path is ≤200T / D, the pull amount per unit cross-sectional area of the branch path is ≤55T / (D*m). 2 ); When 200T / D < total pull amount of branch path ≤ 300T / D, 55T / (D*m) 2 <70T / (D*m) of pull per unit cross-sectional area of branch path 2 ); When 300T / D < total pull amount of branch path ≤ 400T / D, 70T / (D*m) 2 < 80T / (D*m) of pull per unit cross-sectional area of branch path 2 ).
[0010] The branch passage edge temperature control system includes a guide duct, valves, and thermocouples. The guide duct passes through the breast wall of the branch passage, with its air inlet located outside the branch passage and connected to an external cooling air source. The air outlet of the guide duct is located above the molten glass at the edge of the branch passage. The valve is installed at the air inlet, and the thermocouples are installed at the top of the branch passage arch. The thermocouples are grouped in sets of three, with the thermocouples in the same group evenly spaced laterally above the molten glass in the branch passage, and each thermocouple being at the same height from the molten glass.
[0011] The branch passage edge temperature regulation system is controlled by the following method: when the temperature difference is less than 50℃, the valve opening on the guide pipe is increased; when the temperature difference is greater than 60℃, the valve opening on the guide pipe is decreased.
[0012] The pressure detection device consists of a pressure tapping pipe and a pressure gauge. The pressure tapping pipe is installed at the breast wall of the branch passage and communicates with the inside of the branch passage through a through hole in the breast wall. The pressure tapping pipe is connected to the pressure gauge to detect the pressure change in the branch passage after the cooling airflow is introduced.
[0013] The temperature detection device includes two sets of infrared thermal imaging systems. The lenses of the two sets of infrared thermal imaging systems are respectively arranged on both sides of the overflow port, and the display ends are arranged in the control room. Each set of infrared thermal imaging systems monitors the temperature data of the glass melt at multiple points at half of the overflow port.
[0014] The control method of the overflow port temperature and pressure regulation system is as follows: First, adjust the height of each flame deflector brick according to the temperature information detected by the temperature detection device so that the lateral temperature difference between the edge and the middle of the overflow port meets the requirements; second, detect the atmospheric pressure in the branch passage. If the atmospheric pressure in the branch passage is negative, reduce the overall height of the flame deflector brick device.
[0015] The beneficial effects of this invention are as follows: By controlling the pulling amount, combining the branch path edge temperature adjustment system to adjust the lateral temperature difference between the branch path edge and the middle of the branch path, and the overflow port temperature and pressure adjustment system to adjust the atmospheric pressure in the branch path and the lateral temperature difference between the overflow port edge and the overflow port middle, this invention can reduce the number of bubbles and stones in the molten glass and effectively control the thickness difference of the glass plate after forming, thereby improving the overall quality of photovoltaic rolled glass products. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the branch passage edge temperature regulation system of the present invention.
[0017] Figure 2 This is a schematic diagram of the overflow port temperature and pressure regulation system of the present invention.
[0018] In the diagram, 1-branch passage, 2-bottom of pool, 3-pool wall, 4-breast wall, 5-arch top, 6-guide air duct, 7-air inlet, 8-valve, 9-air outlet, 10-observation hole in breast wall, 11-thermocouple, 12-overflow port, 13-flame baffle brick, 14-lens end of infrared thermal imaging system, 15-hole, 16-hanging chain, 17-pressure tapping pipe. Detailed Implementation
[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0020] It should be noted that, as Figure 1-2 As shown, the branch passage 1 and overflow port 12 described in this invention are existing technologies in glass melting furnaces. The branch passage 1 consists of a pool bottom 2, a pool wall 3, a breast wall 4, and an arch top 5. The overflow port 12 is the tail structure of the branch passage 1. This invention mainly achieves the corresponding technical effects by controlling the temperature and pressure of the molten glass flowing through the branch passage 1 and the overflow port 12.
[0021] like Figure 1-2As shown, this invention discloses a method for improving the quality of photovoltaic rolled glass, comprising: when the molten glass flows through the branch passage 1 in the melting furnace, controlling the amount of pull per unit cross-sectional area of the branch passage 1, and using a branch passage edge temperature regulation system to reduce the temperature at the edge of the branch passage 1, controlling the lateral temperature difference δ1 between the edge of the branch passage 1 and the middle of the branch passage 1 to be 50℃-60℃; when the molten glass flows out from the overflow port 12, using an overflow port temperature and pressure regulation system to control the atmospheric pressure in the branch passage 1 to be positive, and simultaneously reducing the lateral temperature difference δ2 between the edge of the overflow port 12 and the middle of the overflow port.
[0022] This invention controls the pulling amount using the ratio of the total pulling amount of the branch path to its cross-sectional area. The ratio of the total pulling amount of the branch path to its cross-sectional area is considered as the pulling amount per unit cross-sectional area of the branch path. The pulling amount per unit cross-sectional area of the branch path is controlled by the following method, as follows: When the total pull amount of the branch path is ≤200T / D, the pull amount per unit cross-sectional area of the branch path is ≤55T / (D*m). 2 ); When 200T / D < total pull amount of branch path ≤ 300T / D, 55T / (D*m) 2 <70T / (D*m) of pull per unit cross-sectional area of branch path 2 ); When 300T / D < total pull amount of branch path ≤ 400T / D, 70T / (D*m) 2 < 80T / (D*m) of pull per unit cross-sectional area of branch path 2 ).
[0023] The principle of this invention is as follows: This invention employs the adjustment of the temperature at the edge of the branch passage and the pulling amount of the branch passage. By controlling and increasing the temperature difference between the edge glass melt and the middle glass melt in the branch passage, the flow rate of the edge glass melt can be reduced, the outflow rate of the edge glass melt can be reduced, and the outflow rate of the middle glass melt can be increased. This reduces the interference of the edge glass melt of the branch passage on the forming flow and reduces the number of bubbles and stones in the photovoltaic rolled glass melt. In a branch channel with a fixed cross-sectional area, the greater the pull amount, the faster the glass melt flow rate. Although the glass melt temperature is lower and the viscosity is higher at the edges, resulting in slower flow, the faster-flowing glass melt in the middle has a driving effect on the glass melt at the edges when the overall flow rate increases, which is not conducive to reducing the speed at the edges. This invention uses the pull amount per unit cross-sectional area to control the overall glass melt flow rate in the branch channel within a reasonable range, reducing the driving effect of the main flow rate on the glass melt at the edges, and making it easier to reduce the flow rate of the glass melt at the edges. After the molten glass flows out of the branch passage and into the overflow port, it is directly exposed to the air and dissipates heat quickly, especially at the edges of the molten glass. Therefore, the lateral temperature difference of the molten glass at the overflow port is large, which also causes a large difference in lateral viscosity. During calendering, the viscosity difference will cause uneven thickness and defects such as excessive thickness difference in the lateral direction. The overflow port temperature and pressure regulation system can reduce the temperature difference between the edges and the middle of the molten glass at the overflow port and the atmospheric pressure in the branch passage 1, so that the viscosity of the formed molten glass is more uniform in the lateral direction and the thickness difference of the formed glass plate is reduced.
[0024] The branch passage edge temperature control system includes a guide duct 6, a valve 8, and thermocouples 11. The guide duct 6 passes through the branch passage breast wall 4, with its air inlet 7 located outside the branch passage and connected to an external cooling air source. The air outlet 9 of the guide duct 6 is located above the molten glass at the edge of the branch passage. The valve 8 is installed at the air inlet 7, and the thermocouples 11 are installed at the top of the branch passage arch. The thermocouples 11 are grouped in sets of three, with each group's thermocouples 11 evenly spaced laterally above the molten glass in the branch passage, and each thermocouple 11 is at the same height from the molten glass. Specifically, the guide duct 6 enters the branch passage 1 through the observation hole 10 in the breast wall. The guide duct 6 guides the cooling airflow to the edge of the branch passage 1, reducing the temperature of the molten glass at the edge of the branch passage 1, while minimizing the impact of the introduced cold airflow on the molten glass in the middle. The guide duct 6 is made of heat-resistant stainless steel and can be used for extended periods at 1300℃.
[0025] The branch passage edge temperature regulation system is controlled by the following method: when the temperature difference is less than 50℃, the opening of the guide pipe valve is increased; when the temperature difference is greater than 60℃, the opening of the guide pipe valve is decreased.
[0026] The overflow port temperature and pressure regulation system includes a flame baffle brick device, a temperature detection device, and a pressure detection device. The pressure detection device consists of a pressure tapping pipe 17 and a pressure gauge. The pressure tapping pipe 17 is installed at the breast wall of the branch passage 1 and communicates with the inside of the branch passage 1 through a through hole on the breast wall 4. The pressure tapping pipe 17 is connected to the pressure gauge to detect the pressure change in the branch passage 1 after the cooling airflow is introduced.
[0027] The flame deflector device includes multiple flame deflectors 13 arranged side by side above the overflow port 12. Each flame deflector 13 is connected to a lifting mechanism on its upper part. The lifting mechanism adjusts the lateral temperature difference of the glass melt at the overflow port 12 and the atmospheric pressure in the branch passage 1 by adjusting the opening of the flame deflector 13. In one embodiment of the present invention, the lifting mechanism is a hanging chain 16 driven by an external sprocket. The hanging chain is connected to the flame deflector 13 through a hole 15 on the flame deflector 13. The opening of the corresponding flame deflector 13 can be adjusted individually by the hanging chain 16.
[0028] The temperature detection device includes two sets of infrared thermal imaging systems. The lens ends 14 of the two sets of infrared thermal imaging systems are respectively arranged on both sides of the overflow port 12, and the display ends are arranged in the control room. Each set of infrared thermal imaging systems monitors the temperature data of the glass melt at multiple points at half of the overflow port 12. In one embodiment of the present invention, each display end is provided with 5 temperature monitoring points, for a total of 10 temperature monitoring points in the entire horizontal direction.
[0029] The control method of the overflow port temperature and pressure regulation system is as follows: First, adjust the height of each flame deflector brick 13 according to the temperature information detected by the infrared thermal imaging system so that the lateral temperature difference between the edge of the overflow port 12 and the middle of the overflow port 12 meets the requirements; second, detect the atmospheric pressure in the branch passage 1. If the atmospheric pressure in the branch passage 1 is negative, reduce the overall height of the flame deflector brick device. Example
[0030] The branch passage edge temperature control system in Example 1 uses 6 sets of guide ducts 6, 3 sets on each side of the branch passage. The 6 sets of guide ducts 6 are symmetrically arranged on both sides of the branch passage 1, and are numbered 1#, 2#, and 3# from the inlet to the outlet of the branch passage. Thermocouples 11 are in groups of three, for a total of three groups. Each group of thermocouples 11 is distributed in the middle and on both sides of the branch passage. The height of each thermocouple 11 from the glass melt is the same, and the distance from the lower end of the arch top 5 is 0.5-1m. Example 1 maintains a total pull amount of 300T / D for the branch path, and a pull amount of 66T / (D*m2) per unit cross-sectional area. In Example 1, without the use of the air guide duct 6, the temperature difference between the edge and the middle of the branch passage is approximately 20°C. After using the air guide duct 6 to deliver cooling air, the temperature difference can be controlled at 55°C. The opening degree of the valve 8 on the air guide duct 6 at this time is shown in Table 1 below: Table 1:
[0031] The overflow outlet temperature and pressure regulation system in Example 1 uses a flame-deflecting brick device consisting of five flame-deflecting bricks 13. Each infrared thermal imaging system of the temperature detection device has five temperature monitoring points on its display end, for a total of ten temperature monitoring points horizontally. The distances of the five flame-deflecting bricks 13 from the upper surface of the molten glass are adjusted from left to right to 100mm, 110mm, 130mm, 110mm, and 100mm. Compared to the previous method using a single flame-deflecting brick at a height of 110mm from the molten glass, the horizontal temperature difference at the overflow outlet 12 is reduced. A detailed comparison is shown in Table 2 below. Table 2:
[0032] When each part of the split flame-blocking brick 13 is at the above-mentioned opening, the pressure in the branch passage is 4 Pa, which can maintain a slight positive pressure.
[0033] After using this technical solution in production, the overall quality of the glass was improved to a certain extent. The number of bubbles decreased from 40 per hour to 26, the number of stones decreased from 15 per hour to 8, the thickness difference of 2mm glass decreased from 0.15mm to 0.12mm, and the total yield increased from 83.5% to 87%.
[0034] In summary, the method for improving the quality of photovoltaic rolled glass proposed in this invention can reduce the number of bubbles and stones in the molten glass and effectively control the thickness difference of the glass sheet after molding, thereby improving the overall quality of photovoltaic rolled glass products.
[0035] The parts of this invention not described in detail are prior art.
Claims
1. A method for improving the quality of photovoltaic rolled glass, characterized in that, include: When the molten glass flows through the branch passage in the melting furnace, the amount of pull per unit cross-sectional area of the branch passage is controlled, and the temperature at the edge of the branch passage is reduced by the branch passage edge temperature regulation system, and the lateral temperature difference δ1 between the edge and the middle of the branch passage is controlled to be 50℃-60℃; when the molten glass flows out from the overflow port, the lateral temperature difference δ2 between the edge and the middle of the overflow port is reduced by the overflow port temperature and pressure regulation system, and the atmospheric pressure in the branch passage is controlled to be positive. The overflow outlet temperature and pressure regulation system includes a flame deflector brick device, a temperature detection device, and a pressure detection device. The flame deflector brick device includes multiple flame deflector bricks arranged side by side above the overflow outlet. Each flame deflector brick is connected to a lifting mechanism on its upper part. The lifting mechanism adjusts the lateral temperature difference of the molten glass at the overflow outlet and the atmospheric pressure in the branch passage by adjusting the opening of the flame deflector bricks.
2. The method for improving the quality of photovoltaic rolled glass according to claim 1, characterized in that: The pulling amount per unit cross-sectional area of the branch path is controlled by the following method, as follows: When the total pull amount of the branch path is ≤200T / D, the pull amount per unit cross-sectional area of the branch path is ≤55T / (D*m). 2 ); When 200T / D < total pull amount of branch path ≤ 300T / D, 55T / (D*m) 2 <70T / (D*m) of pull per unit cross-sectional area of branch path 2 ); When 300T / D < total pull amount of branch path ≤ 400T / D, 70T / (D*m) 2 < 80T / (D*m) of pull per unit cross-sectional area of branch path 2 ).
3. The method for improving the quality of photovoltaic rolled glass according to claim 1, characterized in that, The branch passage edge temperature control system includes a guide duct, valves, and thermocouples. The guide duct passes through the breast wall of the branch passage, with its air inlet located outside the branch passage and connected to an external cooling air source. The air outlet of the guide duct is located above the molten glass at the edge of the branch passage. The valve is installed at the air inlet, and the thermocouples are installed at the top of the branch passage arch. The thermocouples are grouped in sets of three, with the thermocouples in the same group evenly spaced laterally above the molten glass in the branch passage, and each thermocouple being at the same height from the molten glass.
4. The method for improving the quality of photovoltaic rolled glass according to claim 3, characterized in that, The branch passage edge temperature regulation system is controlled by the following method: when the temperature difference is less than 50℃, the valve opening on the guide pipe is increased; when the temperature difference is greater than 60℃, the valve opening on the guide pipe is decreased.
5. The method for improving the quality of photovoltaic rolled glass according to claim 1, characterized in that, The pressure detection device consists of a pressure tapping pipe and a pressure gauge. The pressure tapping pipe is installed at the breast wall of the branch passage and communicates with the inside of the branch passage through a through hole in the breast wall. The pressure tapping pipe is connected to the pressure gauge to detect the pressure change in the branch passage after the cooling airflow is introduced.
6. The method for improving the quality of photovoltaic rolled glass according to claim 1, characterized in that, The temperature detection device includes two sets of infrared thermal imaging systems. The lenses of the two sets of infrared thermal imaging systems are respectively arranged on both sides of the overflow port, and the display ends are arranged in the control room. Each set of infrared thermal imaging systems monitors the temperature data of the glass melt at multiple points at half of the overflow port.
7. The method for improving the quality of photovoltaic rolled glass according to claim 1, characterized in that, The control method of the overflow port temperature and pressure regulation system is as follows: First, adjust the height of each flame deflector brick according to the temperature information detected by the temperature detection device so that the lateral temperature difference between the edge and the middle of the overflow port meets the requirements; second, detect the atmospheric pressure in the branch passage. If the atmospheric pressure in the branch passage is negative, reduce the overall height of the flame deflector brick device.