Dust bag filter mechanism – – insulated mechanism

First, the isolated capture mechanism.

The fibrous layer filter material is composed of many individual fibers. First, the mechanism of the capture of individual fibers is studied. When the dust-containing airflow flows around the fiber body, the interception effect, the inertial effect, the diffusion effect, the electrostatic effect, and the gravity effect occur, trapping the dust particles.

Inertial effect

When the dust particles move along the current line near the fiber body, the gas flows around and the larger mass dust particles deviate from the current line by the inertial force, move tangentially and collide with the trapped fiber.

Interception effect

When dust particles move along the streamline near the fiber body, most fine dust particles flow around with airflow, and only dust particles with a radius greater than or equal to the distance between the center of the dust particle and the edge of the fiber are trapped by the interception of the fiber.

Dissemination effect

Particles with a particle size of 0.1 microns produce an irregular Brownian diffusion under the action of the thermal motion of the fluid molecules, leaving the current line trapped by the fibers. For particles of 0.1 microns, the diffusion distance can reach 17 microns per second at room temperature. The smaller the particle size and the higher the temperature of the dust-containing gas, the more obvious the diffusion benefit.

Electrostatic effect

Dust particles or fibers are charged by induction of friction or an external electric field. When the polarities of the two charges are opposite, under the action of the Coulomb force, the dust particles are attracted to the fibers and trapped.

Effect of gravity

When the particle size of the dust particles is larger, the mass is heavier and the velocity of the airflow is lower, the dust particles separate from the path of motion under the action of gravity, and the surface of the fiber settles and picks up.

Besides, there is the van der Waals effect of intermolecular attraction, the thermally induced migration effect caused by the temperature difference, and the concentration diffusion effect caused by a concentration difference.

The various trapping effects above are described using individual fibers as isolated trapping groups. In fact, the filtering function is a large number of fiber aggregates arranged ina certain organizational structure, and the fibers affect each other. At the same time, filtering. The process is usually not a single effect for publication, but multiple effects at the same time. The capture effect of various capture effects varies with the size of the dust particles and the level of the flow velocity.

It can be seen that for dust particles with a particle size greater than 1.0 micron, inertial collision, gravity, and interception effects are dominant, and for particles with a particle size less than 0.2 micron, molecular diffusion, and electrostatic effects are dominant; When the flow velocity is greater than 15 cm/s the effect of inertial collision is strengthened. When the flow velocity is less than 5 cm/s, the effects of gravity, interception, and diffusion are evident.