The burnout of dust collector filter bags is caused by the superposition of multiple factors, which can be fundamentally categorized into five major types of
inducements:
Flue Gas Temperature Overrun
Prolonged Over-temperature: If the flue gas temperature continuously exceeds the maximum temperature resistance limit of filter bags (e.g., 130℃ for polyester,
190℃ for PPS), the filter material will carbonize, harden and shrink, or melt, resulting in perforations.
Instant High Temperature: Abnormal furnace conditions, process fluctuations or heat exchanger failures will cause a sharp rise in flue gas temperature, which directly
burns the surface of the filter bag.
High-temperature Shrinkage: Over-temperature reduces the length/diameter of the filter bag, leaving it tightly fastened to the cage under continuous stress, which
accelerates aging and embrittlement.
Intrusion of Sparks and Incandescent Particles
Direct Spark Burn-through: The flue gas carries unburned coke and metallic sparks. When the dust layer on the filter bag surface is too thin, these sparks will directly
burn through the filter bag to form round holes.
Retention of Incandescent Particles: Under the working conditions of dry quenching coke and biomass, red hot coke and incandescent coke particles enter the dust
collector, attach to the surface of the filter bag, continuously accumulate heat and burn the fibers.
Heat Accumulation and Spontaneous Combustion of Combustible Dust
Spontaneous Combustion of Dust Accumulated on Filter Bag Surface: When the accumulated thickness of coal dust, aluminum powder and biomass dust exceeds 5mm,
they will oxidize slowly and release heat in an environment above 80℃ with abundant oxygen, and spontaneously ignite when the temperature reaches the ignition
point, thus igniting the filter bag.
Heat Accumulation of Dust in Hopper: If the dust in the ash hopper is not discharged in time, the combustible substances will burn inside the hopper, continuously
baking the filter bag until it becomes brittle and burns out.
Secondary Combustion of the System: If the dust collector is not tightly sealed, the oxygen content will be too high, and the combustible dust will undergo secondary
combustion in the aerobic environment.
Defects in Material Selection and System Design
Incorrect Filter Bag Selection: Using normal-temperature filter bags in high-temperature working conditions, or selecting filter materials that are not compatible with
the corrosive components in the flue gas will cause the filter bag to age and damage in advance, and it will be ignited immediately when encountering sparks.
Ignition by Static Spark: Friction between the insulated filter bag and dry dust generates static electricity of tens of thousands of volts. If the dust collector has poor
grounding, sparks will be discharged and ignite the combustible dust within the explosive limit.
Failure of Dust Cleaning System: An excessively long dust cleaning cycle leads to dust accumulation, or excessively high dust cleaning pressure causes filter bag damage,
forming a short-circuit zone for high-temperature flue gas.
Omissions in Operation and Maintenance
No Pre-coating of New Filter Bags: If pre-coating is not carried out after replacing new filter bags online, the high-temperature flue gas carrying sparks will directly
contact the exposed filter material, which is extremely prone to burn damage.
Absence of Early Warning and Inspection: The failure of temperature monitoring sensors makes it impossible to detect over-temperature in time; if the dust is not
completely cleaned before shutdown, the residual dust will spontaneously ignite during unattended operation.
Illegal Hot Work Operations: When performing operations such as welding around the dust collector without isolation protection, sparks will be sucked into the filter
bag area by the air flow and cause combustion.
