In the modern industrial system, glass, as an important fundamental material, is widely used in construction, automotive, electronics, packaging, and many other fields. With the continuous development of the global economy and the acceleration of urbanization, the market demand for glass is growing steadily. However, the rapid development of the glass industry has also led to severe energy consumption issues. According to statistics, the energy consumption of the glass industry accounts for a considerable proportion of total industrial energy consumption, and the total volume continues to rise, placing dual pressures on energy supply and the environment.

 

In the glass production process, the glass furnace, as the core thermal equipment, is the main source of energy consumption. Its energy consumption level directly affects the overall production cost and energy utilization efficiency. During operation, a glass furnace consumes large amounts of fuel (such as natural gas, heavy oil, coal) and electricity to heat raw materials to high temperatures and melt them into a homogeneous molten glass. Typically, glass melting energy consumption accounts for 30% to 75% of the total energy consumption of the entire glass industry, with the specific proportion varying depending on the glass type, production process, and glass furnace type. Simultaneously, the proportion of energy costs in glass production costs cannot be ignored, usually between 10% and 25%, and is even higher in some small enterprises with backward technology. The combustion efficiency of the glass furnace has a direct and critical impact on production costs. Combustion efficiency refers to the ratio of the effective heat actually released by the fuel during combustion to the theoretical calorific value of complete combustion. Higher combustion efficiency means the fuel is fully combusted, more chemical energy is converted into thermal energy, providing sufficient heat for glass melting, thereby reducing fuel consumption, lowering energy procurement costs, and reducing pollutant emissions from incomplete combustion, thus decreasing environmental treatment costs. Conversely, low combustion efficiency requires more fuel to meet the heat demand, significantly increasing production costs, and may lead to unstable glass melting quality, such as uneven temperature, increased bubbles, and other issues, affecting product quality and yield, further driving up costs.

 

From the perspective of energy consumption, improving the combustion efficiency of glass furnaces is a key measure to reduce the energy consumption of the glass industry. Against the backdrop of increasingly tight global energy resources and continuously rising energy prices, reducing energy consumption is crucial for the sustainable development of glass enterprises. On one hand, improving combustion efficiency consumes less energy to produce the same quantity and quality of products, alleviating energy supply pressure and reducing the risk of production interruptions; on the other hand, it also complies with national energy conservation and emission reduction policies, helping enterprises reduce carbon emissions, fulfill social responsibilities, and enhance corporate image and market competitiveness. Therefore, in-depth research on its role and active exploration of improvement methods are of great significance for the sustainable development of the glass industry.


 

1. Analysis of the Role of Glass furnace Combustion Efficiency

 

1.1 Core Lever for Cost Control

 

The combustion efficiency of a glass furnace is closely related to energy costs and is a key factor affecting glass production costs. Fuel costs account for a relatively large proportion of the total cost, and the level of combustion efficiency directly determines the amount of fuel consumption. When combustion efficiency is high, the fuel is fully combusted in the glass furnace, releasing more effective heat, providing sufficient thermal energy for glass melting, thereby reducing fuel usage for producing the same quantity and quality of products.

 

For example, a large glass enterprise adopted advanced combustion technology and equipment, optimized the combustion system, and increased the glass furnace combustion efficiency from 60% to 80%. Before optimization, the company‘s annual fuel cost was 50 million yuan; after improvement, the fuel cost dropped to 37.5 million yuan, saving 12.5 million yuan annually. This case fully demonstrates that efficient combustion can significantly reduce fuel consumption, save energy procurement costs, and enhance economic benefits.

 

In addition, improved combustion efficiency can indirectly reduce other related costs. For example, reduced fuel consumption can lower the logistics costs required for transportation; complete combustion reduces pollutant emissions, reducing environmental treatment inputs, such as the operation and maintenance costs of exhaust gas treatment equipment. Therefore, improving combustion efficiency is an important means for glass enterprises to achieve cost control and enhance market competitiveness.

 

1.2 Invisible Guardian of Glass Quality

 

Combustion efficiency has a crucial impact on glass quality, mainly reflected in heat distribution and the physical and chemical properties of the molten glass. When combustion efficiency is high, the fuel is fully combusted, and heat is distributed more evenly within the glass furnace, which is conducive to the glass melting and refining process, ensuring all parts of the glass batch are fully heated and the molten glass temperature remains consistent.

 

If heat distribution is uneven, it may lead to local temperatures being too high or too low. Excessively high temperatures can cause the molten glass to be over-melted, changing its chemical composition and affecting optical performance and mechanical strength; excessively low temperatures may lead to incomplete melting of raw materials, leaving unmelted particles, forming internal defects, and reducing glass transparency and uniformity. Uniform heat distribution helps stabilize the melting and refining process, reduce internal defects, and improve glass quality. Uniform heat distribution also helps improve the optical performance and mechanical strength of the glass. For optical glass, internal defects can cause light scattering and refraction, affecting transmittance and refractive index; high combustion efficiency and uniform heat distribution can reduce such defects, meeting the requirements for high-end applications. In terms of mechanical strength, uniform heating allows the molten glass to contract more evenly during cooling, reducing internal stress, improving impact resistance and bending resistance, and enhancing glass durability.

 

1.3 Secret to Extending Glass furnace Life

 

Efficient combustion has a significant protective effect on the service life of glass furnaces, mainly involving the erosive impact of combustion products on refractory materials. When combustion efficiency is low, incomplete combustion of fuel produces reducing gases such as carbon monoxide, hydrocarbons, and unburned particles. These substances interact with oxygen, water vapor, etc., forming corrosive gases or compounds.

 

For example, sulfur dioxide combines with water vapor to form sulfurous acid, which is further oxidized into sulfuric acid, corroding refractory materials and reducing their strength and stability; nitrogen oxides form corrosive substances like nitric acid in high-temperature and humid environments, damaging refractory materials. Efficient combustion reduces the content of corrosive gases and unburned substances, alleviating erosion on refractory materials and extending their service life.

 

A glass enterprise optimized its combustion system through technical transformation, improving combustion efficiency. Before the transformation, the glass furnace refractory materials required large-scale replacement every 2 years at a cost of 2 million yuan, and frequent repairs affected production; after the transformation, the service life of the refractory materials was extended to 5 years, with replacement costs reduced to 2 million yuan every 5 years, while also reducing the frequency and cost of repairs. This not only reduced equipment replacement costs but also improved glass furnace operating stability and production efficiency, bringing significant economic benefits.

 

2. Insight into the Current Status of Glass furnace Combustion Efficiency

 

Currently, the overall level of combustion efficiency in China‘s glass furnaces is not optimistic, generally below 30%, which is a significant gap compared to the international advanced level (40% to 50%, with some top technologies reaching over 50%). This gap limits the competitiveness of Chinese glass enterprises in the international market and poses severe challenges to sustainable development.

 

There are multiple reasons for the low combustion efficiency, with the unreasonable fuel-to-air ratio being the most prominent. During combustion, a reasonable fuel-to-air ratio is key to achieving efficient combustion. However, due to insufficient precision in combustion control systems, varying levels of technical skill among operators, inaccurate monitoring, and other factors, ratio deviations often occur. When the air supply is insufficient, the fuel cannot fully contact oxygen, resulting in incomplete combustion, causing energy waste and generating harmful gases such as carbon monoxide and hydrocarbons, increasing the difficulty and cost of exhaust gas treatment. Research shows that when the air supply is 10% below the theoretical demand, the incomplete combustion rate can reach 20% to 30%.

 

Aging combustion equipment is also an important factor leading to low efficiency. Some glass furnace combustion equipment has been used for a long time, lacking timely maintenance and updates, with problems such as severe wear, decreased sealing performance, and degraded burner performance, affecting fuel injection and air mixing effects, and reducing combustion efficiency. For example, wear of the burner nozzle can lead to uneven fuel distribution, with local concentrations too high or too low, causing incomplete combustion. Aging equipment is also prone to frequent failures, affecting normal production and increasing costs.

 

The instability of the combustion process should not be ignored. Factors such as fuel quality fluctuations, changes in thermal load, and changes in ambient temperature and humidity can all affect the combustion process. If adjustments and optimizations cannot be made in time, it can easily lead to unstable combustion. For example, when the fuel calorific value suddenly decreases, if the fuel supply or air ratio is not adjusted, the combustion temperature will drop, and efficiency will decrease. Unstable combustion may also cause fluctuations in molten glass temperature, affecting melting quality and yield rate, increasing the scrap rate and energy consumption.

 

3. Exploration of Methods to Improve Glass furnace Combustion Efficiency

 

3.1 Application of Advanced Combustion Technologies

 

3.1.1 Analysis of Oxy-Fuel Combustion Technology

 

Oxy-fuel combustion technology uses high-purity oxygen (purity greater than 90%) as the combustion-supporting gas, abandoning the traditional air combustion-supporting method. About 78% of the nitrogen in the air does not participate in combustion but absorbs heat and is discharged with the flue gas, causing heat loss. Oxy-fuel combustion technology eliminates the influence of nitrogen, allowing the fuel to react with oxygen in a pure environment, significantly improving combustion intensity.

 

In practical applications, oxy-fuel combustion technology greatly improves combustion efficiency. On one hand, without nitrogen dilution, the temperature in the combustion zone increases, the flame is more concentrated, and the heat acts more densely on the glass batch, accelerating the melting and reaction process, and improving melting efficiency. Research shows that the melting rate of glass furnaces using oxy-fuel combustion technology is 20% to 30% higher than that of traditional air combustion-supporting glass furnaces, and production efficiency is significantly improved. On the other hand, this technology reduces heat loss, improves thermal efficiency by 15% to 25%, and greatly reduces energy consumption.

 

Oxy-fuel combustion technology also has a positive impact on flame shape and thermal radiation. Increased oxygen concentration accelerates flame propagation speed, covering a wider range, uniformly covering the glass batch, ensuring all parts are fully heated, and improving the quality and uniformity of the molten glass. At the same time, the high-temperature flame has stronger thermal radiation capability, efficiently transferring heat and accelerating the melting and refining process. However, oxy-fuel combustion technology also faces challenges. The water vapor content increases during combustion, which may erode refractory materials and metal parts at high temperatures, shortening their service life. Therefore, adopting this technology requires selecting refractory materials that are more resistant to high temperatures and corrosion, and optimizing the glass furnace structure and equipment design.

 

3.1.2 Explanation of Oxygen-Enriched Combustion Technology

 

Oxygen-enriched combustion technology improves combustion conditions by increasing the oxygen content in the combustion-supporting air (to 25% to 35%), thereby improving combustion efficiency and energy utilization. Traditional air has only 21% oxygen content, and the contact and reaction between fuel and oxygen are insufficient, resulting in slow combustion speed and low efficiency. Oxygen-enriched combustion technology increases oxygen concentration, provides a more abundant oxidizer, and enables faster and more complete fuel combustion.

 

After the oxygen content is increased, the collision probability between fuel molecules and oxygen molecules increases, the combustion reaction rate accelerates, the flame propagation speed increases, combustion becomes more intense, more heat is released per unit time, the glass furnace temperature increases, promoting rapid melting and reaction of glass batch, and improving production efficiency. At the same time, complete combustion reduces the generation of incomplete combustion products, reduces energy waste, and improves energy utilization. Research shows that after adopting oxygen-enriched combustion technology, the fuel consumption of glass furnaces is reduced by 10% to 20%, and energy utilization is improved by 10% to 15%.

 

For example, a flat glass enterprise carried out oxygen-enriched combustion technology transformation, increasing the oxygen content in the combustion-supporting air to 30%. After the transformation, the glass furnace combustion condition significantly improved, the flame became brighter and more stable, the glass melting speed accelerated, and production efficiency increased by 15%. At the same time, fuel consumption significantly reduced, saving about 100,000 cubic meters of natural gas per month, and energy costs decreased by 15%. In addition, complete combustion reduced the content of carbon monoxide and hydrocarbons in the exhaust gas, reducing environmental pollution.

 

3.2 Optimization of Glass furnace Structural Design

 

3.2.1 Strategies for Improving Thermal Insulation Performance

 

The thermal insulation performance of a glass furnace is crucial to its thermal efficiency. Selecting high-quality insulation materials and improving the insulation structure are key to enhancing thermal insulation performance. In the selection of insulation materials, priority should be given to materials with low thermal conductivity and excellent insulation performance, such as ceramic fiber materials, which have a thermal conductivity of 0.03 to 0.05 W/(m·K) and can effectively prevent heat transfer. Compared with traditional insulation materials, ceramic fiber materials have better insulation effects, significantly reducing the surface heat loss of the glass furnace.

 

Ceramic fiber materials also have advantages such as light weight, high temperature resistance, and good chemical stability, reducing the glass furnace load, lowering structural requirements, adapting to high-temperature environments, and extending service life. In addition, nano insulation materials are gradually being applied. Their nano-scale pore structure inhibits heat conduction by gas molecules, with thermal conductivity as low as 0.01 to 0.02 W/(m·K), further reducing heat loss.

 

Improving the insulation structure is also an important measure. Reasonably design the thickness and number of layers of the insulation layer to form an effective thermal barrier. Increasing the thickness of the insulation layer can increase the resistance to heat transfer; adopting a multi-layer insulation structure can utilize the interface effect between different materials to reduce the thermal conductivity coefficient. For example, first lay ceramic fiber blanket on the glass furnace wall, then cover it with nano insulation boards, and finally seal it with insulation coating, giving full play to the advantages of the materials and achieving the best insulation effect.

 

In terms of sealing treatment, the sealing of connection parts and openings should be ensured to prevent heat loss through gaps. Use materials such as sealant and gaskets to seal glass furnace doors, observation ports, pipeline interfaces, etc., and regularly inspect and maintain them, replacing aged and damaged materials in time. By selecting high-quality insulation materials and improving the insulation structure, the heat loss of the glass furnace can be reduced by 30% to 50%, thermal efficiency can be significantly improved, energy consumption can be reduced, and production benefits can be enhanced.

 

3.2.2 Measures for Improving Ventilation Performance

 

Optimizing the design of the ventilation system to ensure uniform air distribution inside the glass furnace is the key to improving ventilation performance. Reasonably arrange the position and number of air inlets and outlets so that air enters the glass furnace from multiple directions, avoiding local air shortage or surplus; the outlets should consider the airflow path to discharge exhaust gas in time and maintain normal circulation.

 

Zoned ventilation can be adopted. According to the temperature and combustion requirements in different areas inside the glass furnace, adjust the ventilation volume separately. Increase the air intake in the glass melting area to support combustion; appropriately reduce the ventilation volume in the cooling area to avoid excessive cooling. Precisely control the ventilation volume in each area to achieve uniform air distribution, improve combustion efficiency and molten glass quality.

 

Installing air guiding devices is also an effective method. Set up devices such as guide vanes and ducts inside the glass furnace to guide the direction of air flow and make it more evenly distributed. The guide vanes can be adjusted according to the airflow situation to change the flow direction and avoid the airflow impacting refractory materials or the molten glass; the ducts can deliver air to specific locations to ensure sufficient oxygen supply.

 

Regularly clean ventilation pipes and equipment to prevent dust and debris from blocking the passages and ensure ventilation performance. Dust accumulation in ventilation pipes increases air flow resistance, reduces ventilation efficiency, and affects air distribution. Therefore, they should be regularly cleaned and maintained to ensure smooth flow. By optimizing the ventilation system design and ensuring uniform air distribution, the glass furnace can maintain a stable temperature, avoid energy waste caused by temperature fluctuations, improve glass melting quality and yield rate, reduce production costs, and enhance economic benefits.

 

3.3 Precise Control of Process Parameters

 

3.3.1 Precise Regulation of Glass furnace Temperature and Pressure

 

According to the requirements of the glass production process, precise control of glass furnace temperature and pressure is a key link to achieving efficient combustion and high-quality production. Different production stages have strict requirements for glass furnace temperature. In the melting stage, the glass furnace temperature needs to be raised to 1500–1600°C to fully melt the raw materials and undergo chemical reactions, forming a uniform molten glass. If the glass furnace temperature is too low, the raw materials will not melt completely, affecting quality; if it is too high, it may increase gas solubility, generating defects such as bubbles, while also increasing energy consumption.

 

In the refining stage, the glass furnace temperature needs to be appropriately reduced to 1400–1500°C to promote bubble discharge and chemical composition homogenization. Fluctuations in glass furnace temperature will affect the bubble discharge effect, leading to residual bubbles and reducing transparency and strength. Therefore, precise control of glass furnace temperature is crucial to ensure glass quality and reduce energy consumption.

 

Glass furnace pressure control is equally critical. Excessively high pressure can cause flame ejection, resulting in heat loss and safety hazards. Conversely, excessively low pressure leads to air infiltration, which reduces the temperature and compromises both combustion efficiency and product quality. Typically, the glass furnace pressure should be maintained at a slightly positive level of 5 Pa to 10 Pa. This is achieved by installing pressure sensors and control dampers to monitor and adjust the pressure in real time, ensuring it remains stable within the set range.

 

To achieve precise regulation, advanced automatic control systems can be used. These systems collect parameters such as glass furnace temperature and pressure in real time through sensors, transmit them to the controller, and automatically adjust the burner fuel supply, the amount of combustion-supporting air, and the air volume of the ventilation system according to preset parameters and algorithms to achieve precise control. The automatic control system has fast response speed and high control accuracy, improving the stability and controllability of the production process, reducing energy consumption, and improving quality and production efficiency.

 

3.3.2 Reasonable Adjustment of Feeding Speed

 

The feeding rate must be adjusted appropriately based on the glass furnace combustion conditions and the glass melting rate. This is a critical measure to ensure complete melting of the batch and to prevent energy waste. If the feeding rate is too high, the batch will not have sufficient time to melt completely. Consequently, unmelted material will be carried along with the molten glass, adversely affecting the final product quality. This situation also leads to energy waste and increased costs, as the unmelted batch must be reprocessed and melted again, consuming additional energy. If the feeding speed is too slow, the heat inside the glass furnace cannot be fully utilized, leading to excessively high temperatures, increasing energy consumption, and possibly damaging refractory materials and shortening the glass furnace life. Therefore, reasonably adjusting the feeding speed to match the combustion situation and melting speed is key to improving combustion efficiency and production quality.

 

To achieve reasonable adjustment, it is necessary to monitor the combustion situation in the glass furnace and the glass melting speed in real time. By installing temperature sensors, level sensors, and other equipment, obtain information such as temperature and molten glass level in real time to judge the melting speed; at the same time, monitor parameters such as the flame state of the burner and the composition of the flue gas to understand the combustion situation. Based on the monitoring data and production experience, adjust the operating speed of the feeding equipment in time to achieve optimal control.

 

Advanced automatic feeding systems can also be used to automatically adjust the feeding speed according to preset programs and real-time monitoring data. By linking the feeding speed with the combustion situation and melting speed for control, production automation and intelligence can be achieved, improving production efficiency and product quality, and reducing energy consumption and costs. For example, when the system detects a temperature increase and accelerated melting speed, it automatically increases the feeding speed to fully utilize the heat; when the combustion situation is poor or the melting speed slows down, the system automatically reduces the feeding speed to avoid the generation of unmelted raw materials.

 

3.4 Application of Advanced Monitoring and Control Systems

 

3.4.1 Application of Flue Gas Analysis Technology

 

Real-time monitoring of the content of oxygen, carbon dioxide, carbon monoxide, and other gases during the combustion process through flue gas analysis technology is an important means to optimize the combustion process and achieve energy conservation and emission reduction. The composition and content of combustion products reflect combustion efficiency and quality. Analyzing flue gas can obtain key information and provide a basis for adjusting combustion parameters.

 

Oxygen content is an important indicator. Excessive oxygen content indicates that the air supply is too much, the fuel has not fully reacted, there is excess air, leading to heat being taken away, reducing efficiency, and increasing energy consumption; excessively low oxygen content indicates insufficient air supply, the fuel cannot burn completely, producing incomplete combustion products such as carbon monoxide, wasting energy and polluting the environment. Therefore, monitoring oxygen content can help adjust the air-to-fuel ratio in time to keep the combustion in the best state.

 

Carbon dioxide content is also an important parameter reflecting combustion efficiency. During complete combustion, the carbon in the fuel is completely converted into carbon dioxide, and the content is high; when efficiency is low, the content decreases, and other products such as carbon monoxide are generated. Monitoring carbon dioxide content can judge whether the combustion is sufficient and adjust the combustion conditions to improve efficiency.

 

Carbon monoxide is a product of incomplete combustion of fuel, and its content directly reflects the degree of combustion completeness. If the content exceeds the standard, it indicates problems in the combustion process, and it is necessary to find the cause and make adjustments in time, such as adjusting the air-to-fuel ratio, increasing the combustion temperature, optimizing burner performance, etc., to ensure complete fuel combustion, reduce emissions, and achieve the goal of energy conservation and emission reduction.

 

Based on the flue gas analysis results, adjust parameters such as fuel supply, combustion-supporting air volume, and burner operating status in time to optimize the combustion process. For example, when the oxygen content is too high, reduce the supply of combustion-supporting air; when the carbon monoxide content exceeds the standard, increase the air supply or increase the combustion temperature. Through continuous monitoring and adjustment, keep the glass furnace combustion in an efficient, energy-saving, and environmentally friendly state.

 

3.4.2 Advantages of Automatic Control Systems

 

Automatic control systems have many significant advantages in the glass furnace combustion process. They can precisely control the combustion process, improve controllability and predictability, reduce energy consumption risks, and improve production efficiency. Traditional operations mainly rely on manual experience, which is subjective and unstable, making it difficult to precisely control parameters, easily leading to fluctuations in the combustion process, affecting quality and efficiency. Moreover, it is unable to monitor and process large amounts of data in real time, making it difficult to detect problems in time, increasing energy consumption risks and costs.

 

Automatic control systems overcome these shortcomings. Through sensors installed in various parts of the glass furnace (such as temperature, pressure, flow sensors, etc.), operating data is collected in real time and transmitted to the central processor. The processor analyzes and processes the data according to preset programs and algorithms, automatically issues control instructions, and adjusts parameters such as fuel supply, combustion-supporting air volume, and ventilation system air volume to achieve precise control.

 

Automatic control systems also have high stability and reliability, are not affected by human factors, operate stably according to preset programs, ensure the consistency and stability of the combustion process, improve product quality stability, reduce the defect rate, and improve efficiency. The system can also monitor and warn in real time. When it detects that parameters are out of range or abnormal, it immediately issues an alarm and provides fault diagnosis information to help operators solve problems in time, avoid accidents, and reduce energy consumption risks and costs.

 

By analyzing and mining historical production data, the system can provide support for production decisions, predict energy consumption trends, equipment operating status, etc., helping enterprises reasonably arrange production plans, optimize energy management, and improve economic benefits and competitiveness. For example, by analyzing historical data to predict energy consumption under different production conditions, enterprises can adjust process and equipment parameters accordingly to reduce energy consumption and improve efficiency.

 

3.5 Rational Selection of Refractory Materials—Taking Fused Cast AZS Block as an Example

 

Fused cast AZS block, as a commonly used key refractory material in glass furnaces, has characteristics that make it suitable for high-temperature and complex working environments, playing an auxiliary role in improving combustion efficiency. Fused cast AZS block is mainly composed of alumina (Al₂O₃), zirconia (ZrO₂), and silica (SiO₂). Its unique chemical composition gives it excellent performance.

 

From the perspective of high-temperature resistance, fused cast AZS block has a high load softening temperature, generally above 1790°C, allowing it to maintain stable physical form and structural strength in high-temperature environments without softening, deforming, or collapsing, maintaining the normal operation of the glass furnace. When the temperature in the melting end reaches 1500–1600°C, ordinary refractory materials are difficult to withstand, while fused cast AZS block performs excellently.

 

Improving the combustion efficiency of glass furnaces is of great significance for the sustainable development of the glass industry. By applying advanced combustion technologies, optimizing glass furnace structural design, precisely controlling process parameters, using advanced monitoring and control systems, and rationally selecting refractory materials, combustion efficiency can be effectively improved, production costs can be reduced, glass quality and glass furnace life can be improved, and energy consumption and environmental pollution can be reduced. In the future, with technological progress and innovation, combustion efficiency is expected to be further improved, and the glass industry will move towards a more energy-saving, environmentally friendly, and efficient direction, making positive contributions to global sustainable development.



Henan SNR Refractory Co., Ltd. is dedicated to the manufacture, research and development of fused cast AZS refractory blocks and bonded refractory materials for the glass industry. Meanwhile, SNR can provide total solutions and services for glass furnace design, glass furnace construction, renovation, and upgrading. Please contact me if you have any requirements.

CONTACT: 

zoe@snrefractory.com/ WhatsApp:+86 18172389584