What Filtration Velocity to Choose for Boiler Dust Collectors?

What filtration velocity should be selected for boiler dust collectors? A proper selection of filtration velocity is not only crucial for meeting emission standards, but also of great economic significance for enhancing the equipment's capacity to treat dust-laden gas, reducing equipment investment and thus cutting project costs. So how to correctly determine the filtration velocity of boiler dust collectors?

Impacts of Filtration Velocity on Equipment

A relatively high filtration velocity can reduce the filtration area and equipment volume, save floor space and lower investment costs. However, an excessively high filtration velocity will compromise dust removal efficiency, increase the difficulty of ash cleaning, raise filtration resistance, shorten the service life of dust filter bags, and lead to higher operation and maintenance expenses. In fact, determining the filtration velocity is a complex task; it is insufficient to view the above advantages and disadvantages in isolation, and finding a balanced solution to this issue is the top priority.

Considerations for Dust Collection Accessories in Velocity Selection

In recent years, with increasingly stringent environmental protection requirements, the rational determination of filtration velocity has become extremely important in the design of baghouse dust collectors for boilers. Based on practical experience, the filtration velocity of boiler dust collectors should be set below 0.8 m/min to ensure optimal dust removal performance.

Dust collectors for coal-fired boilers mostly adopt high-temperature baghouse systems due to the high temperature of flue dust, which requires high-temperature filter media for the filter bags accordingly. High-temperature filter media typically have a basis weight of around 850 g/㎡, which is much thicker than normal-temperature filter media, resulting in lower air permeability. Therefore, the internal filtration velocity of the dust collector should also be appropriately reduced to guarantee the stable operation of the equipment.

The internal filtration velocity of high-temperature baghouse dust collectors is recommended to be controlled at 0.8 m/min. For scenarios with ultra-strict emission standards, it is preferable to keep the internal filtration velocity at 0.6 m/min. The internal filtration velocity is selected according to different emission standards, which in turn determines the filtration area of the dust collector.

Once the filtration velocity is fixed, and with the typical treated air volume of a boiler being 3000 m³/h, the model selection of dust collectors for boilers of different tonnages can be finalized. The calculation formula for filtration area is as follows:

Filtration Area = Treated Air Volume /60 / Internal Filtration Velocity

The model of the dust collector is determined based on the calculated filtration area.