What Controls the Dust Cleaning System of Pulse Jet Baghouse Dust Collectors?

The dust cleaning system of a pulse jet baghouse dust collector is mainly controlled by three key parameters: jet pressure, jet cycle and jet duration. The setting of these three parameters directly affects the operation of the dust collector. Below is a detailed breakdown of their technical specifications:

Jet Pressure

Jet pressure refers to the pressure of compressed air for pulse jetting. A higher jet pressure induces more secondary air flow and a greater reverse air velocity, resulting in better dust cleaning efficiency and a more significant drop in the operating pressure difference of the dust collector. With the jet interval and jet duration unchanged, an increase in jet pressure allows for a corresponding rise in the inlet dust concentration. However, excessively high jet pressure can cause over-cleaning, which in turn impairs purification efficiency and leads to an instantaneous dust emission from the baghouse. It also increases air consumption and causes energy waste. Both overly low and excessively high jet pressure will adversely affect filtration performance.

Tests show that a considerable portion of compressed air pressure (up to more than 0.2MPa) is consumed to overcome the resistance of the jet system itself, with the pulse valve accounting for a large share of this resistance. In recent years, several types of low-resistance pulse valves have been developed, such as straight-through pulse valves and double-diaphragm low-pressure pulse valves. Their significantly reduced internal resistance enables a corresponding drop in jet pressure, giving rise to low-pressure jet systems with a minimum jet pressure of 0.2MPa–0.3MPa.

In addition, increasing the diameter of air tanks and jet pipes, and replacing jet orifices with nozzles can all reduce jet pressure. When determining jet pressure, in addition to the resistance of the pulse valve, the length of filter bags should also be considered: lower jet pressure is used for short filter bags, and the pressure needs to be increased accordingly for long filter bags.

Jet Cycle

Jet cycle refers to the time interval (in seconds) from the end of one operation of a pulse valve to the end of its next operation. The length of the jet cycle directly impacts the pressure drop of the dust collector. For pulse jet baghouses with timing control, the jet interval is set by the pulse controller. Adjusting the jet interval can maintain the dust collector's pressure drop at a stable level during operation. Under the premise of not affecting normal operation, the jet interval should be extended as much as possible. This reduces compressed air consumption, minimizes damage to pulse valve diaphragms and filter bags, and extends their service life. While extending the jet interval cuts the power consumption of the jet system, an excessive increase in the dust collector's pressure drop will lead to higher power consumption of the induced draft fan.

Jet Duration

Jet duration (also known as pulse width) is the time during which the pulse valve remains open for jetting. Generally, a longer jet duration delivers more compressed air into the filter bags and achieves better dust cleaning efficiency, but the improvement in efficiency becomes insignificant once the jet duration exceeds a certain value.

With a fixed filtration velocity and inlet dust concentration, the relationship between jet duration and the dust collector's pressure drop varies with different jet pressures. Initially, the pressure drop drops rapidly as jet duration increases; when the duration reaches a certain value, the pressure drop decreases only slightly, while the compressed air consumption doubles or even more.

Therefore, the effect of adjusting jet duration to reduce the dust collector's pressure drop is limited. The jet duration is generally set between 0.1s and 0.2s, with a common setting of 0.15s. Based on the above analysis, controlling the jet pressure at 0.3–0.4MPa and the jet duration at 100–150ms can meet dust cleaning requirements. In actual engineering sites, the jet pressure and duration can be adjusted according to the actual compressed air supply.