Analysis of the Service Life of Oxy-Fuel Combustion Glass Furnaces

Time:2025-06-12 Views:26

Oxy-fuel combustion technology, a significant innovation in the glass industry, is increasingly replacing traditional air-fuel methods due to its energy efficiency and low emissions. However, furnace lifespan remains a critical challenge for widespread adoption. By examining key factors—including design, materials, construction, and operation—it proposes standardized, scientific, and systematic approaches to extend service life through advanced materials and processes. The findings offer theoretical and practical insights for optimizing oxy-fuel furnace performance, supporting the industry’s green transition.

1. Characteristics of Oxy-Fuel Combustion Technology
2. Applications of Oxy-Fuel Combustion Technology
3. How to Improve Furnace Service Life
4. Outlook

1. Characteristics of Oxy-Fuel Combustion Technology
Oxy-fuel combustion (also known as pure oxygen combustion) utilizes a fuel + oxygen combustion mode. Compared to traditional air-fuel combustion in glass furnaces, this technology eliminates the involvement of large amounts of nitrogen from the combustion air, making energy savings more achievable. Additionally, it results in lower initial NOx emissions, easier pollution control, and more predictable outcomes.With the rapid advancement of domestic oxygen production technology and reduced electricity costs, oxy-fuel combustion (oxygen + fuel) has become a superior alternative to conventional air-fuel combustion in modern industries.

This is due to its outstanding performance in:
Environmental protection
Energy efficiency
Increased production capacity
Improved product quality
Reduced equipment investment
Savings in factory space
Currently, oxy-fuel combustion technology has been widely adopted in China across industries such as metallurgy, power generation, chemicals, building materials, and processing.

2. Applications of Oxy-Fuel Combustion Technology

In China, oxy-fuel furnaces were first applied in display devices (CRT) in 2001, with most early technologies being imported from abroad. However, the real expansion of this technology occurred in electronic glass-ceramics. Today, oxy-fuel combustion is used in the production of:Glass-ceramics;High borosilicate glassware;High-alumina glass (e.g., cover glass);Pharmaceutical glass (low/medium borosilicate glass);Soda-lime glass (yellow tint);Optical glass;Solar photovoltaic glass;Electronic materials;Low-melting-point glass;Lead-free glass (lighting);Glass wool;High-lead glass;Glass microspheres;Fiberglass;Ceramic & enamel glazes;Daily-use bottles & containers;Water glass (sodium silicate);Basalt fiber.
Advantages of Oxy-Fuel Combustion:

(1) Energy savings & reduced consumption(improves economic efficiency)
(2)Enhanced product quality (especially for products requiring specific combustion conditions, such as high temperature, atmosphere, or color—where traditional air-fuel furnaces struggle)
(3)Effective NOx reduction solution
(4)Compliance with carbon emission regulations(some regions mandate oxy-fuel for new production capacity approvals due to environmental policies).

2.1 Service Life of Oxy-Fuel Glass Furnaces

2.1.1 Normal Furnace Lifespan

The industry has established conventional benchmarks for furnace lifespans. Meeting these benchmarks is considered acceptable—for example, opaque glass furnaces are generally expected to operate for 18 months.For glass furnaces (whether air-fuel or all-electric), there are no mandatory international regulations or guidelines on service life. However, with advancements in new technologies, materials, and processes, the average lifespan of furnaces, including oxy-fuel furnaces, has been gradually increasing.Furnaces that fail to meet or approach industry-recognized lifespans—or shut down after only a few months—are typically deemed abnormal failures or malfunctions.

2.1.2 Key Factors Affecting Furnace Lifespan

(1) Design
A well-executed design is half the battle for a successful project.
Furnace design is a systematic engineering task, involving:
Mechanical and thermal calculations
Fluid dynamics
Refractory material science
Structural mechanics
Instrumentation and control
With tightening environmental policies, exhaust gas treatment must also be integrated into the design framework.
A comprehensive design should cover:Process layout, furnace dimensions, and energy distribution;Flame space optimization, length-to-width ratio;Molten glass/combustion gas flow velocities;Refractory material specifications (size, type, quantity);Steel structure design;Control systems (e.g., DCS);Burner selection and configuration;Electrical component specifications;Process control points and adjustment protocols;Furnace construction, installation, heat-up, and insulation;Environmental protection systems;Pre-project feasibility studies (EIA, safety assessments);Post-commissioning technical support and process optimization.
Current Industry Issues:Some domestic companies undervalue design, opting to copy existing blueprints. This approach risks stunting technological progress and industry competitiveness.

(2) Refractory Material Selection
Refractory selection is a systematic process.Designers must understand material properties and match them to the furnace’s product requirements.Evaluate suppliers based on quality control, pricing, and reliability.
Special Considerations for Oxy-Fuel Furnaces:
Due to differences in combustion space temperature, melting rate, and flue gas moisture concentration (vs. air-fuel furnaces), high-quality fused cast AZS materials from reputable manufacturers are critical.
Key areas requiring attention include:
Throat (flow channel)
Bubbling zones
Electrode blocks
Doghouse corners
Discharge blocks
Crown (main arch)
For these areas, higher-zirconia fused cast refractory blocks (e.g., Fused Cast AZS #41 Blocks) are required for enhanced erosion resistance.

(3) Construction Quality
The quality of construction is another critical factor influencing furnace longevity.
Standardized construction should encompass:
Safety protocols
Environmental compliance
Project management coordination
While reputable contractors may charge higher fees, their guaranteed workmanship significantly extends furnace service life. Cutting corners on construction often leads to premature failures.
(4) Process Regime
The establishment of a sound process regime is not only critical for ensuring stable product quality, rational energy consumption indicators, and environmental compliance, but also serves as a key factor in extending furnace service life.For different furnaces, products, and pull rates, a scientific and well-calibrated process regime must be implemented.
Key components of the process regime include:

Temperature profile
Energy distribution
Glass level and furnace pressure control
Batch pile management
Bubbling or electric heating adjustments
Stirring techniques
Overflow or discharge methods
A competent design team should develop a preliminary process protocol during the furnace design phase. This protocol must then be continuously refined based on operational data and production challenges until a finalized, optimized regime is established.

(5) Operation
To achieve extended furnace campaign life, proper operation and usage are equally critical alongside the aforementioned factors.
As a key indicator of glass furnace productivity, the melting rate is prioritized by both design institutes and end-users. Determining an optimal melting rate requires comprehensive evaluation of multiple factors:

Product specifications

Batch formulation

Cullet ratio

Furnace structure

Glass quality requirements

Refractory material selection

Ancillary equipment configuration
Industry Challenges:

While design institutes typically propose conservative yet realistic melting rate targets, some may overstate capabilities amid intensifying market competition.

Plant operators, under market pressures or profit-driven motives, often arbitrarily increase pull rates.
Without corresponding upgrades to furnace dimensions or combustion technology, such practices typically involve:

Modifying batch recipes
Raising melting temperatures

These adjustments compromise both product quality and furnace longevity.
(6）Batch Material Changes

Some manufacturers, driven by market demands, frequently switch batch formulations—or even transition to entirely different products—within a single furnace campaign. This practice significantly impacts furnace longevity, introducing additional risks (e.g., refractory stress, thermal instability), particularly during the furnace’s late operational stages. Such scenarios require heightened monitoring and mitigation measures.
(7) Heat-Up (Thermal Treatment)
Referred to as "heat treatment" by some furnace engineers, the heat-up process tests a supplier’s comprehensive technical capabilities.Critical Considerations for Oxy-Fuel Furnaces: Dry masonry construction (common in oxy-fuel combustion chambers) demands precision heat-up protocols.Poorly executed heat-up increases risks of flame penetration and refractory damage.
Expertise Required:
Temperature ramp rate control
Material selection for expansion joints
Emergency response procedures
Hands-on experience with oxy-fuel furnace characteristics
(8) Cooling Systems
Some domestic enterprises underestimate the importance of furnace cooling, with some even rejecting sidewall cooling due to perceived energy costs. This misconception accelerates refractory erosion and shortens furnace life.
Scientific Approach to Cooling:
Integrated design calculations (heat flux, cooling capacity)
Proper equipment selection (cooling blocks, media flow rates)
Commissioning and operational optimization Fact:
A well-designed cooling system reduces long-term energy losses by maintaining refractory integrity and minimizing repair downtime.
(9) Routine Maintenance

For furnaces with identical configurations, daily maintenance practices determine lifespan disparities.Best Practices:Preventive inspections: Early detection of issues (flame penetration, material leakage, hot spots);Data-driven decisions: Analyze inspection logs to identify wear patterns;
Timely interventions: Address minor anomalies before they escalate
Critical Warning Signs Requiring Immediate Action:
• Flame breakthrough
• Batch material squeezing
• Refractory glowing
Proactive maintenance is the most cost-effective method to extend furnace service life.

2.1.3 Key Strategies for Optimal Furnace Lifespan

To scientifically and rationally evaluate furnace lifespan, it is essential to adopt a "refractory consumption per ton of glass" mindset. While a longer furnace lifespan is generally desirable, its design and management must balance multiple factors:
Construction costs
Product characteristics
Economic viability
End-user requirements
Blindly pursuing an ultra-long lifespan without considering these factors may lead to diminishing returns and market rejection.
(1) Setting a Realistic Melting Rate
Melting rate should not be maximized at all costs. The ideal rate depends on: Product specifications (e.g., glass composition, quality standards);Process constraints (e.g., energy distribution, temperature profile);Investor priorities (e.g., capital vs. operational cost trade-offs)
Best Practice:Establish a techno-economically balanced target and ensure stable operation at that level.
(2) Dynamic Adjustment of Melting Rate

Melting rates should not remain static. Production managers must adapt based on: Refractory wear (e.g., accelerated erosion in late-campaign phases);Operational risks (e.g., hot spots, glass leakage threats)
Critical Action:Proactively reduce melting rates during the furnace’s later stages to mitigate failure risks.
(3) Hazards of Forced Melting
Some designers artificially inflate melting rates by:
Overheating the pre-melting zone
Sacrificing thermal efficiency
Negative Impacts:
Energy consumptionVolatilization of glass components (e.g., boron, lead)
Furnace lifespan due to refractory stress
Industry Warning:
Short-term output gains often lead to higher lifetime costs from premature repairs or rebuilds.

3. How to Improve Furnace Service Life

3.1 Standardization

(1) To achieve an ideal furnace service life, the owner must first select a design institute with proven experience and track record, firmly believing that good products stem from good design.
(2) Secondly, choose a construction contractor with experience in building and heat-up of oxy-fuel furnaces. Oxy-fuel combustion furnaces differ significantly from traditional air-fuel furnaces in terms of furnace construction, heat-up procedures, and thermal treatment. Although the absence of regenerator checkerwork reduces construction workload, the quality requirements for masonry become more stringent. Special attention must be paid to heat-up curves as they vary considerably depending on materials and furnace structure.
(3) Standardize process parameters. Avoid excessive human intervention and arbitrary adjustments to process controls, particularly in pull rates and temperature regimes.
(4) For refractory materials - especially those in contact with molten glass, in combustion spaces, and in areas potentially causing glass contamination - insist on using compliant materials that meet specifications to avoid negative impacts from substandard materials.
(5) Pay utmost attention to equipment that may affect product quality, particularly components critical to furnace longevity and operational safety. These require high-level priority.
(6) Daily inspection and maintenance. While oxy-fuel furnaces eliminate periodic reversing operations (significantly reducing labor intensity), they demand higher staff responsibility. Strict adherence to inspection protocols, proper documentation of equipment records, and planned maintenance are essential to ensure furnace longevity.

3.2 Scientific Operation

When operating oxy-fuel furnaces, operators must first abandon conventional mindsets. Respect the inherent principles of oxy-fuel technology and strictly follow operating procedures.Some owners, influenced by long-term operation habits from air-fuel furnaces, fail to properly adapt to oxy-fuel furnace operation. They neglect data collection and analysis, leading to untargeted problem-solving. A common misconception is addressing seed defects (sometimes called "pitting" or "orange peel" defects) by simply increasing fuel input and raising temperatures. Without proper process controls and thermal gradients, such temperature increases not only waste energy but also adversely affect furnace service life.

3.3 Systematic Approach

A holistic consideration must be given to design philosophy, material and equipment selection, operational contingency plans, and process control, with balanced resource allocation. Simply increasing investment in one area to address a particular issue should be avoided.As a complex system engineering project, a glass furnace consists of multiple interconnected components. Any weak link in this system can compromise the overall furnace lifespan - this is the essence of the "barrel theory" (where the shortest stave determines capacity).

3.4 Innovation

The application of new materials, technologies, and processes forms the foundation for broader adoption of oxy-fuel furnaces in the future.Key developmental directions include:

Low-momentum combustion technology
Thermal oxygen technology
Hydrogen energy combustion
Submerged combustion
Hybrid combustion technologies

Many of these emerging technologies promise revolutionary improvements in extending furnace service life, making them highly anticipated advancements.

4. Outlook
Oxy-fuel combustion technology has been applied in the glass industry for over 30 years globally, with 20 years of accumulated experience in China. Recent years have seen accelerated adoption due to product upgrades and environmental policies, propelling this technology onto a fast development track.Providing customers with stable, reliable, advanced, and safe oxy-fuel furnaces represents the shared mission of all industry professionals.To further enhance the service life of oxy-fuel glass furnaces, comprehensive improvements must be made across:
Design solutions
Material selection
Furnace construction
Process parameter establishment
Furnace maintenance protocols
The application of new technologies, materials, and processes demands a scientific and rigorous approach, where technological innovation becomes the key driver for extending furnace longevity.

Henan SNR Refractory Co., Ltd. has been specializing in the production of fused cast AZS blocks for about 25 years. We use high-quality raw materials and advanced fusion technology to provide customers with high-quality products. From raw material procurement to finished product delivery, every step is strictly quality inspected to ensure that every indicator meets the standards, so you can use it with confidence.