Combustion of Tunnel Kiln Natural Gas Burners and Fan Management Analysis

I. Introduction:
In the production of clay-fired bricks, the tunnel kiln plays a central role in determining product quality, thermal efficiency, and environmental performance. Precise temperature control and atmospheric regulation within the kiln are essential. As traditional coal-stoking and manual ventilation give way to internal combustion and automated control systems, the roles of natural gas burners and fans have become even more critical. This article analyzes the coordination between these two systems and proposes optimization strategies based on modern kiln technology and engineering practices.

II. Overview of the Natural Gas Combustion System in Tunnel Kilns
1. The Central Role of Gas Burners
Natural gas burners are the heart of the tunnel kiln’s heat system, converting chemical energy into thermal energy. Their layout, turn-down ratio, flame pattern, and control integration directly affect sintering quality, energy consumption, and NOx emissions.
Key design parameters:
(1) Thermal power: Must match or exceed the peak thermal load of the firing zone, with a 10–20% design margin.
(2) Turn-down ratio: ≥ 1:10, to ensure stable combustion even under low-load conditions.
(3) Flame geometry: Must match the kiln cross-section (e.g., 6.9m or 9.2m wide) to avoid hotspots and thermal imbalance.
(4) Low-NOx combustion: Equipped with FGR (Flue Gas Recirculation), staged combustion, or low-NOx premixed nozzles to achieve<80 mg/m³ NOx emissions.
(5) Control integration: Burners are linked with PLC modules and sensors for O₂, CO, and temperature, supporting closed-loop DCS control.
2. Combustion Control Strategies
(1) Smart firing curves: Heating–soaking–cooling profiles are dynamically adjusted based on product stages.
(2) Zonal temperature control: Subdivided burner zones ensure fine control and adaptability.
(3Real-time feedback: Sensors drive PID control logic, maintaining efficiency and minimizing oxygen excess.

III. Fan System Optimization
1. Key Functions of Fans in Kiln Operation
(1) Oxygen supply: Supports complete combustion and maintains an oxidizing atmosphere.
(2) Thermal balancing: Distributes hot air evenly, avoiding hot and cold spots.
(3) Exhaust & dehumidification: Removes combustion gases and steam, maintaining safe O₂ levels and relative humidity.
2. Fan Configuration and Performance Parameters

3. Intelligent Fan Control with VFDs
(1) Variable-frequency drives (VFDs) allow fan speed to match real-time demand.
(2) Zone pressure & humidity feedback enables real-time ventilation adjustment.
(3) Air–Fuel–Material modeling enables closed-loop automation between combustion and ventilation.
(4) Avoid short-circuit airflow and dead zones, improving fuel use and temperature uniformity.

IV. Coordinated Optimization of Combustion and Ventilation
1. Oxygen Content and Emission Control
(1) Target O₂ concentration: 16–18%, in line with national environmental baselines.
(2) Over-ventilation risks: Wastes energy and increases flue gas volume, raising NOx and CO₂ emissions.
(3) Core strategy: Eliminate "wrong air" and "waste air," focusing on precision airflow delivery.
2. Aligning Energy Efficiency with Emission Reduction
(1) Pollution control systems have evolved from single-stage bag filters to three-stage systems (dust removal, desulfurization, denitrification), increasing CAPEX.
(2) Controlling airflow helps reduce the pollutant load and cut reliance on expensive filtration systems.
(3) Coordinated airflow control is essential for balancing quality, production efficiency, and environmental compliance.
3. Practical Recommendations
(1) Pressure sensors and local PID loops should be deployed for each kiln zone.
(2) Establish digital “air–fire–product” coupling, forming a responsive closed-loop control system.
(3) Train kiln operators in modern “environmental sintering” operations to align with intelligent standards.

V. Engineering Practice Recommendations (Based on Brictec’s Experience)
1. Burner layout: Use top-staggered + side-wall opposed configuration to ensure uniform firing and minimize cold zones.
2. Fan selection: Opt for VFD-controlled axial fans with thermal feedback integration.
3. Control logic: Employ segmented PID with zone-specific feedback from O₂, temperature, and pressure sensors.
4. Safety integration: Include backdraft protection, flame detectors, and emergency shutoffs.
5. Operational monitoring: Implement real-time data collection (O₂, CO, air speed, temperature) and historical database archiving for system analysis and future optimization.

VI. Conclusion
In modern tunnel kiln systems, natural gas burners and ventilation fans are no longer standalone components—they form an integrated thermal control system. Achieving high sintering quality, optimal fuel efficiency, and low emissions demands precise burner control and intelligent airflow management. Moving forward, the industry must transition from experience-based kiln firing to system-driven smart control, enabling sustainable, high-performance brick production.

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Сжигание природного газа в туннельной печи и анализ управления вентиляторами - Новости отрасли обожжённого кирпича из глины