Float glass production lines are a high-energy-consuming industry. The core equipment, such as the melting furnace and regenerator, generates a large amount of high-temperature flue gas during operation, and the waste heat contained in this flue gas accounts for a significant portion of the total energy consumption of the production line. Waste heat boilers, through targeted design and operation management, can convert this waste heat into steam or hot water for production heating, power generation, and other applications. They are not only important equipment for reducing energy consumption in the production line but also an effective support for environmental protection and emission reduction. Xinli Boiler will summarize the key points of waste heat boiler application practice in float glass production lines, considering the process characteristics of the production line, from the perspectives of application design, operation management, practical effects, and problem solving.
I. Waste Heat Characteristics of Float Glass Production Lines: Application Prerequisites
The application of waste heat boilers must be based on the waste heat characteristics of the float glass production line. The main sources and parameters of waste heat are highly specific to the industry, and can be summarized as follows:
1. Main Sources of Waste Heat: Concentrated in High-Temperature Stages
The waste heat in float glass production lines mainly comes from the flue gas at the furnace outlet and the exhaust gas from the regenerator. These two are the main heat sources for the waste heat boiler.
Furnace outlet flue gas: The temperature is in a high range, making it a high-grade waste heat resource for the production line. The flue gas volume matches the scale of the production line, and it contains a small amount of incompletely burned combustible materials, resulting in high waste heat recovery value.
Regenerator exhaust gas: After heat exchange in the regenerator, the flue gas temperature decreases, but the flue gas volume is basically the same as that at the furnace outlet. The alkali metal salt content in the composition is higher, which is prone to deposition on the heating surface.
2. Core Characteristics of Waste Heat: High Alkali Content, Dust, and Fluctuation
The alkali metal components in the float glass raw materials and the characteristics of fuel combustion lead to the significant characteristics of "high alkali content, dust, and fluctuation" in the waste heat flue gas, which directly affects the design direction of the waste heat boiler.
High alkali content: The concentration of alkali metal compounds in the flue gas is high, and it is easy to form hard slag on the heating surface as the flue gas flows, affecting the heat transfer efficiency.
Dust content: The flue gas contains dust (mainly quartz sand and feldspar particles), and long-term scouring can cause wear on the heating surface. Fluctuation Characteristics: During production line load adjustments (such as changes in glass production) or fuel switching, flue gas temperature and flow rate will fluctuate to a certain extent. Short-term temperature and pressure fluctuations also occur during the furnace firing process, requiring high adaptability from the boiler.
II. Application Practice of Waste Heat Boilers: Key Aspects
The application of waste heat boilers in float glass production lines requires a comprehensive approach encompassing "selection and design – installation and commissioning – operation optimization." Each stage must be matched to the process characteristics of the production line to ensure waste heat recovery efficiency and equipment stability.
1. Selection and Design: Targeted Matching to Float Glass Process
Selection and design are fundamental to the effective operation of waste heat boilers, requiring focus on three key aspects: heat transfer surface design, anti-slagging and anti-wear design, and load adaptation design.
Heat Transfer Surface Design: For high-temperature flue gas from the furnace, a segmented heat transfer surface design of "high-temperature section + medium-temperature section" is adopted. The high-temperature section uses heat-resistant alloy steel for the heat transfer surface components to prevent high-temperature oxidation; the medium-temperature section uses low-alloy steel for the heat exchange elements, connecting to the exhaust from the regenerator to maximize the utilization of waste heat in different temperature ranges. Fin tubes and other structures can be used to enhance heat transfer, and appropriate element spacing is selected based on the flue gas ash content to reduce the risk of ash accumulation.
Anti-Slagging and Anti-Wear Design: The heat transfer surface adopts a co-current flow arrangement to shorten the residence time of alkali metal salts on the tube wall; the diameter of the heat transfer tubes is appropriately increased to reduce the risk of slagging and blockage; wear-resistant protective components are installed at the flue gas inlet to reduce wear on the heat transfer surface caused by dust erosion. Acidic gas corrosion is mitigated by controlling the flue gas temperature at the waste heat boiler outlet to be above the dew point temperature within a certain range.
Load Adaptation Design: The boiler's rated load adjustment range must cover the possible fluctuation range of the production line. Variable frequency induced draft fans and automatic control valves are equipped to quickly adjust the boiler's flue gas and water flow when the production line load fluctuates, avoiding insufficient output or overpressure operation. For companies with multiple production lines, multiple boilers can be connected in parallel to reduce the impact of flue gas parameter fluctuations. 2. Installation and Commissioning: Connecting to the Production Line, Minimizing Production Downtime
Float glass production lines typically operate continuously, so the installation and commissioning of the waste heat boiler must consider both "construction efficiency" and "equipment compatibility" to avoid prolonged production downtime.
Installation Sequence: Prioritize connecting the boiler body to the flue gas ducts of the melting furnace and regenerator. Modular installation methods should be used to shorten the on-site installation period and minimize the impact on continuous production. Flue gas duct modifications require enhanced insulation and sealing, using new insulation materials and sealing structures to reduce heat loss and air leakage. A bypass exhaust gas pipeline should also be installed to ensure quick isolation from the production system in case of boiler failure.
Commissioning Focus: During commissioning, simulate different load conditions of the production line to test the boiler's heat transfer efficiency and pressure stability; simultaneously commission the soot blowing system to ensure effective slag removal and prevent efficiency degradation due to slag buildup after formal operation. Furthermore, the kiln pressure control system needs to be tested, using the coordinated adjustment of flue gas dampers and induced draft fans to ensure stable melting furnace pressure.
3. Operational Optimization: Daily Management to Improve Waste Heat Utilization Rate
The long-term stable operation of the waste heat boiler depends on refined daily management. Key optimization areas include load adjustment, soot blowing management, and water quality control.
Load Adjustment: Adjust boiler operating parameters according to the actual load of the production line to maintain stable steam parameters and avoid waste heat. An automated control system can be used for centralized monitoring and adjustment of parameters, improving operational stability and reducing labor intensity.
Soot Blowing Management: Develop differentiated soot blowing cycles based on the characteristics of alkali metal slagging, setting different frequencies for high-temperature and medium-temperature sections; combine various methods such as sonic, shock wave, or steam soot blowing to both clean slag and avoid excessive soot blowing damage to the heating surface. Regularly check the operating status of the soot blowing device and adjust the blowing intensity and frequency based on the amount of ash accumulation.
Water Quality Control: Strictly control the quality of boiler feedwater, regularly test water quality indicators, prevent scaling or oxygen corrosion of the heating surface, and extend equipment life. Low-pressure steam from the boiler can be used for deoxygenation treatment to optimize the efficiency of the steam-water system.
III. Actual Application Results: Benefits Presented
After applying waste heat boilers in float glass production lines, significant differences in energy consumption and benefits are typically observed. Before application, traditional waste heat recovery equipment was often affected by problems such as slagging and poor load adaptability, resulting in low waste heat utilization rates, significant energy consumption, and frequent downtime due to malfunctions. After the application of waste heat boilers, targeted anti-slagging and load adaptation designs addressed some of the shortcomings of traditional equipment, improving waste heat utilization and steam production. This resulted in significant annual energy savings and reduced carbon emissions, while also improving boiler reliability and reducing downtime. The system thus achieved both economic and environmental benefits. Furthermore, the electricity generated by the waste heat power generation system can be directly used in production and can also serve as an emergency power source during grid failures, reducing the risk of production interruptions.
IV. Common Problems and Solutions in Application
In the application of waste heat boilers in float glass production lines, three types of problems are prone to occur: severe slagging, heat exchange surface wear, and load adaptation deviations. These require targeted solutions.
Severe slagging: If slagging on the heat exchange surface affects heat transfer, the soot blowing frequency and method should be optimized, combined with auxiliary methods such as mechanical vibration to clean the accumulated ash. Simultaneously, the raw material ratio should be checked, and the proportion of alkali metal components in the glass raw materials should be adjusted appropriately to reduce slagging at the source. For highly viscous ash deposits, chemical cleaning agents can be used as an auxiliary treatment.
Heat exchange surface wear: If wear on the heat exchange surface affects equipment safety, wear protection should be strengthened in the flue gas inlet section, wear-resistant components should be replaced, or the flue gas velocity should be adjusted to reduce dust erosion. Reasonable design of the flue gas velocity ensures heat transfer efficiency while reducing the risk of wear.
Load adaptation deviations: If the boiler output fluctuates significantly with the production line load, the automatic control system parameters need to be improved to enhance the timeliness and accuracy of parameter adjustments. By optimizing the linkage logic between the control system and the melting furnace process, the system's adaptability to periodic fluctuations such as flame changes is enhanced.
The core idea of applying waste heat boilers in float glass production lines is "targeted matching of process characteristics"—through designs adapted to high-temperature, high-alkali flue gas and refined operational management, it is possible to maximize waste heat recovery while ensuring the long-term stable operation of the equipment. From practical results, it can effectively improve the waste heat utilization rate of the float glass production line, reduce energy consumption and failure risks, and provide both economic and environmental benefits.
Float glass production lines are a high-energy-consuming industry. The core equipment, such as the melting furnace and regenerator, generates a large amount of high-temperature flue gas during operation, and the waste heat contained in this flue gas accounts for a significant portion of the total energy consumption of the production line. Waste heat boilers, through targeted design and operation management, can convert this waste heat into steam or hot water for production heating, power generation, and other applications. They are not only important equipment for reducing energy consumption in the production line but also an effective support for environmental protection and emission reduction. Xinli Boiler will summarize the key points of waste heat boiler application practice in float glass production lines, considering the process characteristics of the production line, from the perspectives of application design, operation management, practical effects, and problem solving.
I. Waste Heat Characteristics of Float Glass Production Lines: Application Prerequisites
The application of waste heat boilers must be based on the waste heat characteristics of the float glass production line. The main sources and parameters of waste heat are highly specific to the industry, and can be summarized as follows:
1. Main Sources of Waste Heat: Concentrated in High-Temperature Stages
The waste heat in float glass production lines mainly comes from the flue gas at the furnace outlet and the exhaust gas from the regenerator. These two are the main heat sources for the waste heat boiler.
Furnace outlet flue gas: The temperature is in a high range, making it a high-grade waste heat resource for the production line. The flue gas volume matches the scale of the production line, and it contains a small amount of incompletely burned combustible materials, resulting in high waste heat recovery value.
Regenerator exhaust gas: After heat exchange in the regenerator, the flue gas temperature decreases, but the flue gas volume is basically the same as that at the furnace outlet. The alkali metal salt content in the composition is higher, which is prone to deposition on the heating surface.
2. Core Characteristics of Waste Heat: High Alkali Content, Dust, and Fluctuation
The alkali metal components in the float glass raw materials and the characteristics of fuel combustion lead to the significant characteristics of "high alkali content, dust, and fluctuation" in the waste heat flue gas, which directly affects the design direction of the waste heat boiler.
High alkali content: The concentration of alkali metal compounds in the flue gas is high, and it is easy to form hard slag on the heating surface as the flue gas flows, affecting the heat transfer efficiency.
Dust content: The flue gas contains dust (mainly quartz sand and feldspar particles), and long-term scouring can cause wear on the heating surface. Fluctuation Characteristics: During production line load adjustments (such as changes in glass production) or fuel switching, flue gas temperature and flow rate will fluctuate to a certain extent. Short-term temperature and pressure fluctuations also occur during the furnace firing process, requiring high adaptability from the boiler.
II. Application Practice of Waste Heat Boilers: Key Aspects
The application of waste heat boilers in float glass production lines requires a comprehensive approach encompassing "selection and design – installation and commissioning – operation optimization." Each stage must be matched to the process characteristics of the production line to ensure waste heat recovery efficiency and equipment stability.
1. Selection and Design: Targeted Matching to Float Glass Process
Selection and design are fundamental to the effective operation of waste heat boilers, requiring focus on three key aspects: heat transfer surface design, anti-slagging and anti-wear design, and load adaptation design.
Heat Transfer Surface Design: For high-temperature flue gas from the furnace, a segmented heat transfer surface design of "high-temperature section + medium-temperature section" is adopted. The high-temperature section uses heat-resistant alloy steel for the heat transfer surface components to prevent high-temperature oxidation; the medium-temperature section uses low-alloy steel for the heat exchange elements, connecting to the exhaust from the regenerator to maximize the utilization of waste heat in different temperature ranges. Fin tubes and other structures can be used to enhance heat transfer, and appropriate element spacing is selected based on the flue gas ash content to reduce the risk of ash accumulation.
Anti-Slagging and Anti-Wear Design: The heat transfer surface adopts a co-current flow arrangement to shorten the residence time of alkali metal salts on the tube wall; the diameter of the heat transfer tubes is appropriately increased to reduce the risk of slagging and blockage; wear-resistant protective components are installed at the flue gas inlet to reduce wear on the heat transfer surface caused by dust erosion. Acidic gas corrosion is mitigated by controlling the flue gas temperature at the waste heat boiler outlet to be above the dew point temperature within a certain range.
Load Adaptation Design: The boiler's rated load adjustment range must cover the possible fluctuation range of the production line. Variable frequency induced draft fans and automatic control valves are equipped to quickly adjust the boiler's flue gas and water flow when the production line load fluctuates, avoiding insufficient output or overpressure operation. For companies with multiple production lines, multiple boilers can be connected in parallel to reduce the impact of flue gas parameter fluctuations. 2. Installation and Commissioning: Connecting to the Production Line, Minimizing Production Downtime
Float glass production lines typically operate continuously, so the installation and commissioning of the waste heat boiler must consider both "construction efficiency" and "equipment compatibility" to avoid prolonged production downtime.
Installation Sequence: Prioritize connecting the boiler body to the flue gas ducts of the melting furnace and regenerator. Modular installation methods should be used to shorten the on-site installation period and minimize the impact on continuous production. Flue gas duct modifications require enhanced insulation and sealing, using new insulation materials and sealing structures to reduce heat loss and air leakage. A bypass exhaust gas pipeline should also be installed to ensure quick isolation from the production system in case of boiler failure.
Commissioning Focus: During commissioning, simulate different load conditions of the production line to test the boiler's heat transfer efficiency and pressure stability; simultaneously commission the soot blowing system to ensure effective slag removal and prevent efficiency degradation due to slag buildup after formal operation. Furthermore, the kiln pressure control system needs to be tested, using the coordinated adjustment of flue gas dampers and induced draft fans to ensure stable melting furnace pressure.
3. Operational Optimization: Daily Management to Improve Waste Heat Utilization Rate
The long-term stable operation of the waste heat boiler depends on refined daily management. Key optimization areas include load adjustment, soot blowing management, and water quality control.
Load Adjustment: Adjust boiler operating parameters according to the actual load of the production line to maintain stable steam parameters and avoid waste heat. An automated control system can be used for centralized monitoring and adjustment of parameters, improving operational stability and reducing labor intensity.
Soot Blowing Management: Develop differentiated soot blowing cycles based on the characteristics of alkali metal slagging, setting different frequencies for high-temperature and medium-temperature sections; combine various methods such as sonic, shock wave, or steam soot blowing to both clean slag and avoid excessive soot blowing damage to the heating surface. Regularly check the operating status of the soot blowing device and adjust the blowing intensity and frequency based on the amount of ash accumulation.
Water Quality Control: Strictly control the quality of boiler feedwater, regularly test water quality indicators, prevent scaling or oxygen corrosion of the heating surface, and extend equipment life. Low-pressure steam from the boiler can be used for deoxygenation treatment to optimize the efficiency of the steam-water system.
III. Actual Application Results: Benefits Presented
After applying waste heat boilers in float glass production lines, significant differences in energy consumption and benefits are typically observed. Before application, traditional waste heat recovery equipment was often affected by problems such as slagging and poor load adaptability, resulting in low waste heat utilization rates, significant energy consumption, and frequent downtime due to malfunctions. After the application of waste heat boilers, targeted anti-slagging and load adaptation designs addressed some of the shortcomings of traditional equipment, improving waste heat utilization and steam production. This resulted in significant annual energy savings and reduced carbon emissions, while also improving boiler reliability and reducing downtime. The system thus achieved both economic and environmental benefits. Furthermore, the electricity generated by the waste heat power generation system can be directly used in production and can also serve as an emergency power source during grid failures, reducing the risk of production interruptions.
IV. Common Problems and Solutions in Application
In the application of waste heat boilers in float glass production lines, three types of problems are prone to occur: severe slagging, heat exchange surface wear, and load adaptation deviations. These require targeted solutions.
Severe slagging: If slagging on the heat exchange surface affects heat transfer, the soot blowing frequency and method should be optimized, combined with auxiliary methods such as mechanical vibration to clean the accumulated ash. Simultaneously, the raw material ratio should be checked, and the proportion of alkali metal components in the glass raw materials should be adjusted appropriately to reduce slagging at the source. For highly viscous ash deposits, chemical cleaning agents can be used as an auxiliary treatment.
Heat exchange surface wear: If wear on the heat exchange surface affects equipment safety, wear protection should be strengthened in the flue gas inlet section, wear-resistant components should be replaced, or the flue gas velocity should be adjusted to reduce dust erosion. Reasonable design of the flue gas velocity ensures heat transfer efficiency while reducing the risk of wear.
Load adaptation deviations: If the boiler output fluctuates significantly with the production line load, the automatic control system parameters need to be improved to enhance the timeliness and accuracy of parameter adjustments. By optimizing the linkage logic between the control system and the melting furnace process, the system's adaptability to periodic fluctuations such as flame changes is enhanced.
The core idea of applying waste heat boilers in float glass production lines is "targeted matching of process characteristics"—through designs adapted to high-temperature, high-alkali flue gas and refined operational management, it is possible to maximize waste heat recovery while ensuring the long-term stable operation of the equipment. From practical results, it can effectively improve the waste heat utilization rate of the float glass production line, reduce energy consumption and failure risks, and provide both economic and environmental benefits.