What are the effects of high or low filtering air speed on filter bags?

The filtering wind speed is the core operating parameter of the bag filter,which directly determines the filtering load of the filter bag,the formation status of the dust layer,and the cleaning effect.If the wind speed is too high or too low,it will deviate from the design working conditions,not only affecting the overall operating efficiency of the dust removal system,but also causing significant negative effects on the service life and operating status of the filter bag.The fault manifestations and damage mechanisms of the two are significantly different.

Excessive filtering wind speed is the most common parameter loss of control problem in industrial sites,which can cause the filter bag to bear overload operating pressure,leading to a series of chain damage and significantly shortening its service life.Excessive wind speed can rapidly thicken the dust layer on the surface of the filter bag and make it difficult for the cleaning system to effectively blow it off,easily forming a plate structure,directly causing a sudden increase in pressure difference between the inlet and outlet of the dust collector,increasing the operating load of the fan,and at the same time,fine dust will invade the internal pores of the filter material under the push of high-speed airflow,causing blockage and sticking of the filter bag,permanently reducing the permeability of the filter material.High speed airflow can also carry coarse and hard dust to form a"sandblasting effect",continuously scouring weak parts such as the air inlet and bottom of the filter bag,accelerating the thinning and damage of the filter material;Moreover,high wind speeds can cause the filter bag to shake violently during operation,resulting in frequent friction with the cage bones and internal components of the dust collector,which can easily lead to local wire shedding and hole breakage.The high-frequency and high-pressure dust cleaning adopted to alleviate high resistance will repeatedly stretch and impact the filter fiber,causing fatigue aging,and even directly tearing the filter bag.Eventually,due to the unstable formation of the dust layer,fine dust will penetrate the filter material,resulting in excessive dust concentration at the outlet and a significant decrease in dust removal efficiency.

Although a low filtering wind speed does not directly cause physical damage to the filter bag,it can lead to inefficient operation of the dust removal system and indirectly cause filter bag related failures,resulting in waste of equipment resources.The efficient filtration of filter bags relies on the stable initial layer of dust formed on the surface.Low wind speeds can prevent dust particles from quickly and uniformly depositing on the surface of the filter bag,making it difficult to form a qualified initial layer of dust.Fine dust can easily penetrate the filter material,resulting in excessive dust concentration at the outlet of the dust collector and failure to meet the design requirements for dust removal efficiency.At the same time,the airflow velocity inside the filter bag is slow at low wind speeds.If the moisture content of the flue gas is slightly high or there is slight air leakage in the dust collector housing,it is easy to form local condensation on the surface of the filter bag.The viscous dust will adhere to the surface of the filter material to form a thin layer,which gradually solidifies after long-term accumulation,resulting in slow and continuous increase in the resistance of the filter bag.In addition,low wind speed can cause the filter bag to be in a relaxed state,and the blowing airflow during dust cleaning can easily cause the filter bag to expand excessively,bulge,and collide with the cage bone,resulting in slight wear and tear;Moreover,excessively low wind speed means that the filtering area of the dust collector is not effectively utilized,and the overall processing air volume cannot meet the production requirements,resulting in equipment capacity waste and increased operating costs per unit air volume.

GB/T 7714:

ELLENBECKER M J,LEITH D.The Effect of Dust Retention on Pressure Drop in a High Velocity Pulse-Jet Fabric Filter[J].Journal of the Air&Waste Management Association,1980,30(12):1282-1287.

MLA 9th:

Ellenbecker,Michael J.,and David Leith."The Effect of Dust Retention on Pressure Drop in a High Velocity Pulse-Jet Fabric Filter."Journal of the Air&Waste Management Association,vol.30,no.12,1980,pp.1282–1287.

APA 7th:

Ellenbecker,M.J.,&Leith,D.(1980).The effect of dust retention on pressure drop in a high velocity pulse-jet fabric filter.Journal of the Air&Waste Management Association,30(12),1282–1287.