Fire‑proof design for coal grinding systems is a core component of industrial safety. Because coal dust is highly flammable and explosive, relevant standards—such as GB 50414–2018—impose stringent requirements in this regard. The underlying principle is to eliminate potential hazards through preventive design and to mitigate the consequences of accidents by relying on structural safeguards. The following are the key considerations based on national standards and practical experience:
Process Design and Proactive Prevention
Medium and Heat Source Control: The drying medium must be free of sparks; for example, hot-air furnaces should be equipped with exhaust chimneys and separated from the mill by partition walls. The system should be designed to remain sealed, preventing significant air leakage and ensuring that no high‑temperature sources enter the system.
Inerting and parameter control: The key is to limit the oxygen concentration (e.g., to below 12%); simultaneously monitor temperature, with bituminous coal powder not exceeding 70°C and anthracite not exceeding 80°C; furthermore, the residence time within the silo should be controlled—no more than 5 hours for bituminous coal and no more than one week for anthracite—while creatively establishing conditions that promote maximum inerting.
Equipment and Structural Protection
Explosion Resistance and Pressure Relief: Equipment shall be capable of withstanding explosion pressures, and pressure-relief vents shall be installed at the mill outlet, pipelines, dust collectors, and pulverized-coal bins, with the vent openings oriented to avoid personnel and equipment.

Isolation and Fire Suppression: Quick-shut-off valves shall be installed at the inlet and outlet of dust collectors to prevent flame propagation; critical equipment such as dust collectors and coal-powder silos must be equipped with fire-suppression systems (e.g., nitrogen or carbon dioxide). When a fire occurs, the CO concentration will rise; CO concentration data shall be used to determine whether a fire has broken out, and appropriate measures shall be taken promptly.
Monitoring and Control Strategy
Continuous monitoring: Temperature, carbon monoxide, and oxygen concentration monitoring and alarm systems shall be installed at the inlet and outlet of the coal mill, in the pulverized-coal bunker, and in the dust collector.
Stable Operation: Practice has shown that continuous operation is safer than frequent start–stop cycles, as it reduces the risk of oxygen accumulation and explosion.
Operation and Maintenance Management
Hot Work Control: Open flames and smoking are strictly prohibited within the area; any hot work during maintenance must be authorized with a permit and thoroughly cleaned of accumulated dust.
Parking and Cleaning: During extended parking, the coal dust must be completely drained, and the use of compressed air to blow away accumulated dust is strictly prohibited to prevent the formation of dust clouds.

Technical Information on Pulverized Coal Burners and Coal-Pulverizing & Coal-Handling Systems

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