“Four Fatal Factors” of Dust Explosions
Why have flour mills become high-risk areas?
1. Combustible dust: Flour particles typically have a diameter ranging from 5 to 150 μm, with a large specific surface area, making them highly susceptible to suspension and reaching the explosion limit (with a minimum ignition concentration of only 0.05 g/m³).
2. Confined space: The pipelines, storage tanks, dust collectors, etc. in the production workshop form “dust-rich dead zones” that can ignite instantly upon contact with open flames or electrostatic sparks.
3. Energy sources: Mechanical friction, sparks from electrical equipment, and even static electricity generated by workers wearing synthetic clothing (with voltages reaching thousands of volts) can all serve as “fuses”.
4. Chain effect: The initial explosion raises more sedimentary dust, triggering a second, larger explosion, with the destructive power increasing exponentially.
Prevention and control strategy: From passive defense to active immunization
1. Engineering transformation: Eliminating the “breeding ground” for explosions
Explosion-proof zoning design:
In Class A explosion hazard areas (such as grinding rooms and packaging areas), reinforced concrete frame structures are used, with doors and windows opening outwards to avoid the superposition of explosion shock waves.
Installing explosion suppression system: Embedding pressure relief valves and chemical explosion suppression devices in dust collectors and conveying pipelines can inject fire extinguishing agents within milliseconds to suppress flame propagation.
Inertization protection:
Store nitrogen cylinders in flour silos, and automatically replenish nitrogen when the oxygen concentration drops below 12%, thus eliminating the conditions conducive to dust ignition. A case study indicates that this method reduces the risk of explosion by 90%.
2. Source control: Cut off the “lifeline” of dust
Intelligent dust removal system:
Equipped with a pulse-jet bag filter with a filtration accuracy of 0.5μm, coupled with a negative pressure dust suction device, it ensures that the dust concentration in the workshop remains below 25% of the lower explosion limit.
Anti-static full-process control:
The equipment grounding resistance is ≤4Ω, and the conveyor belt is made of conductive rubber to eliminate static electricity accumulation.
Workers should wear anti-static clothing, and it is prohibited to use chemical fiber mops to clean the floor.
3. Monitoring and early warning: building a “digital sentinel”
Real-time sensor network:
Laser dust meters and infrared thermal imaging devices are deployed in key areas. When the dust concentration exceeds the standard or the equipment temperature is abnormal, the system automatically triggers an alarm and activates the sprinkler system.
4. Emergency response system: The “golden plan” for racing against time
Hierarchical response mechanism:
Level 1 warning (dust concentration reaches the critical value): automatically shut down and activate the sprinkler system.
Level 2 warning (localized fire): Power outage throughout the factory, release of foam.
Level 3 warning (explosion occurs): The emergency exit automatically opens, and the broadcasting system guides the evacuation.
Conclusion: Safety is the “lifeline” of a flour mill
From engineering renovation to cultural innovation, from hardware investment to fundamental cognitive transformation, preventing and controlling dust explosions is not a short-term accomplishment. Instead, it requires a three-dimensional protective network built by enterprises with a “zero tolerance” attitude.
Post time: Jul-05-2025