What properties should be considered in the dust collector design

Firstly, the classification of dust.

Industrial dust is dispersed with tiny particles of solid particles in the air. There is no uniform method and name for the classification of dust. We classify the characteristics of dust according to its cause, particle size and different characteristics.

From the health point of view, the more fine dust particles on the human body more serious harm to more than 10 microns of dust should not be inhaled into the respiratory system, and less than 10 microns, especially 5 microns below the dust easily inhaled the body, its harm is relatively large, From the point of view of dust collection, it is more difficult to capture the finer the particle size. As for the dust of 100 microns or more, it is easy to settle the dust. Therefore, the dust collector should be separated from the object of 100 microns or less, especially less than 10 microns.

Secondly, the basic nature of dust.

After the block material crushed into tiny particles, its composition did not change, the nitrogen physical and chemical properties but the difference is large, because the material crushed after the total surface area caused by the surge.

1. dust in the dense state of the weight per unit volume, known as the proportion or true proportion. 

Dust in the natural accumulation of the weight of the unit volume, known as bulk density or bulk specific gravity. Dust in the natural accumulation of the state is not dense, so the capacity is less than the proportion of the proportion of dust for gravity settlement and inertia dust removal equipment will have a greater impact. Bulk weight has an impact on the design of dust storage and transportation equipment.

Crushing the solid material formed by the dust, the period will be on the same raw materials, but the role of dust after oxidation, the proportion will change. In addition, the particles formed by the condensation process are aggregated into aggregates, and the specific gravity of these aggregates is smaller than the specific gravity of the individual particles due to the inclusion of air.

2. the adhesion of dust and wetting

The properties of the dust particles are agglomerated to each other. Dust and the wall, wall water film attached to the nature of the attachment known as adhesion. Cohesion and adhesion are collectively referred to as the adhesion of dust. Cohesive matter dust particles increase, is conducive to separation and improve the efficiency of dust removal, adhesion will dust equipment or ducts inside the dust stickers blocked. Dust adhesion strength, mainly depends on the nature of the dust itself and the outside world conditions.

Dust is water or other liquid wet the degree of difficulty called wetting. Dust that is easily wet with water is called hydrophilic dust; dust that is difficult to be wet with water is called hydrophobic dust or hydrophobic dust. Of course, this classification is relative, for 5 microns below the fine dust even if the hydrophilic dust, only in the dust and water droplets have a high relative velocity can only be wet. Some dust and water contact will occur after the adhesion and hardening, this dust is called hydraulic dust. Wet dust removal equipment is the use of dust and dust this feature. Obviously the hydraulic dust and hydrophobic dust are not the same as the use of wet dust collector to separate.

3. dust charge and conductivity

The dust particles in the air medium are often charged with a certain charge, which may occur during the formation of dust particles, or may be caused by ionizing radiation, corona discharge, and collision with each other. The properties of the dust particles have a certain effect on the stability of the dust particles in the air.

4. burning and explosive

After the solid material crushed, its surface area increased to a large extent, due to the increase in surface area, its chemical activity greatly enhanced. So some of the material after the formation of dust, in the air to reach a certain concentration, and the outside world of high temperature, sparks, friction, collision, etc., will cause the possibility of explosion.

There is danger of explosion dust, but only to a certain concentration, in order to explode, this limit is called the lower limit of the explosion. When designing dust removal systems for such dust, they must comply with the building design fire safety regulations and the relevant professional safety regulations.

5. the angle of repose and slip angle

The resting angle of the dust is the angle between the vertebrae and the slope of the cone that is naturally deposited in the horizontal plane, typically 35-50 °. The dust slip angle is the point where the dust is on a smooth plate so that the inclination to the dust can slide down along a straight line, typically 30 ° -40 °. The size of the angle of repose, the angle of the sliding angle and the nature of the dust, particle size, shape, humidity and other factors have a certain impact.

In the installation of the dust collector system, should make the pipe inclination angle of not less than 40 °, ash tank tilt angle of not less than 50 °, to ensure that the natural fall of dust, and will not cause clogging.

6. particle size and dispersion

Dust particles are very irregular in size and shape, and their size can only be represented by a representative size particle size. For spherical dust particles, the particle size refers to its diameter; for non-spherical dust particles, One of the best representative sizes is the particle size. The particle size distribution of dust is often consistent with certain mathematical laws or empirical formulas. For example, in the process of ventilation and dust removal, crushing and screening of industrial dust is mostly subject to the law of the normal distribution of the law.