The core causes of high differential pressure in baghouse dust collectors can be divided into five major categories, among which filter bag clogging and caking is the
most common primary trigger. For normal operating equipment, the differential pressure generally stays within the range of 800-1500Pa, and a sustained value
exceeding 2000Pa is regarded as an abnormally high state.
Abnormalities of the Filter Bag System
Filter bag clogging and paste bag: High-humidity flue gas, condensation when the temperature drops below the dew point, or oil mist/adhesive substances contained in
the dust will cause the dust to get damp, harden and adhere to the surface of the filter bag, blocking the micropores of the filter material which cannot be removed by
conventional ash cleaning, resulting in a significant drop in air permeability.
Aging and failure of filter bags: Under the long-term influence of high temperature and chemical corrosion, the fiber structure of the filter bag deteriorates and hardens,
and the pores are irreversibly filled, so that the resistance cannot be restored even after ash cleaning.
Improper installation or type selection: Wrinkled and skewed filter bags, poor sealing with the tube sheet, or insufficient reserved filtration area leading to excessive
filtration velocity, which causes local airflow blockage and rapid dust accumulation.
Functional Failure of the Ash Cleaning System
Faults of core components: The diaphragm of the pulse valve is damaged, the coil is burnt out, or the lift valve of the off-line ash cleaning model is not closed tightly,
which results in the fact that the dust cannot be effectively stripped during ash cleaning, and even the situation of "air passing while cleaning ash" occurs, so that the
dust is repeatedly sucked back into the filter bag.
Abnormal injection parameters: When the injection pressure is lower than 0.3MPa, the injection time is too short, and the injection interval is too long, the ash cleaning
speed cannot keep up with the dust accumulation speed, and the dust is compacted layer by layer.
Problems of air source quality: The compressed air contains water and oil, which adheres to the surface of the filter bag along with the injection airflow, aggravating the
dust hardening, and meanwhile blocks the injection holes, leading to uneven ash cleaning distribution.
Deviation of Working Condition Parameters from Design Values
Overload: The actual air volume to be processed is far beyond the design value, leading to excessive filtration velocity; or the upstream process fluctuates, resulting in a
sharp increase in the inlet dust concentration that exceeds the conventional ash cleaning load of the dust collector.
Abnormal temperature and humidity: The flue gas temperature is too low to cause condensation, the humidity is too high, or a large amount of adhesive dust is mixed
in, which directly increases the risk of paste bags and rapidly raises the operating resistance.
Problems of Equipment Body and Structure
Air leakage of the box body: The access doors, flanges, and pipe interfaces are not tightly sealed, a large amount of cold air seeps into the box body, forming a local
low-temperature area to cause condensation, meanwhile disrupting the airflow balance in the box body, leading to serious dust accumulation on local filter bags.
Dust bridging in the ash hopper: The ash discharge valve fails, the dust gets damp and agglomerates, the height of the accumulated dust in the ash hopper exceeds
the
bottom of the filter bag, the secondary lifted dust re-adheres to the filter bag, and meanwhile reduces the gas circulation space.
Air duct blockage: The deflector and the air inlet pipe are covered with dust, the ventilation cross-sectional area becomes smaller, and the overall wind resistance of
the
system increases.
Factors of Instruments, Operation and Maintenance
False faults of meters: The pressure measurement pipeline for differential pressure is blocked and the probe is covered with dust, which leads to an excessively high
reading instead of a real increase in operating resistance.
Non-standard operation and maintenance: Complete ash cleaning is not performed after shutdown, and the residual dust cools, absorbs moisture and hardens; the
front-end pre-treatment equipment (such as the cyclone dust collector) is not cleaned in time, and a large amount of coarse powder directly flows into the filter bags.
