Cement firing equipment includes shaft kiln, wet rotary kiln (rotary kiln), ordinary hollow dry process kiln, LIBOR kiln, preheater kiln (SP) and new dry process rotary kiln (rotary kiln) widely used at present.

Rotary kiln (rotary kiln) is a cylindrical object with an inclination of 3 ~ 3.5%. The rotation of the kiln can promote the mixing of materials in the rotary kiln (rotary kiln), so that the materials can mix and contact each other for reaction. The coal injection combustion at the kiln head produces a lot of heat, which is transmitted to the materials by means of flame radiation, hot gas convection, kiln brick (kiln skin) conduction, etc. The materials move forward in the kiln depending on the inclination of the kiln barrel and the rotation of the kiln.

Working principle of rotary kiln sintering

1) On the one hand, rotary kiln (rotary kiln) is a combustion equipment in which pulverized coal is burned to produce heat; At the same time, it is also a heat transfer equipment. The raw material absorbs the heat of the gas for calcination. In addition, sometimes conveying equipment transports raw materials from the feed end to the discharge end. The fuel combustion, heat transfer and raw material movement must be reasonably coordinated, so that the heat generated by fuel combustion can be transmitted to the raw materials in time when the raw materials pass through the rotary kiln (rotary kiln), and the purpose of high yield, excellent quality and low consumption has been achieved.

2) The movement of raw material particles in rotary kiln (rotary kiln) is relatively complex. If it is assumed that there is no sliding phenomenon of raw material particles on the kiln wall and inside the raw material layer, it is generally considered that the raw material movement is as follows: the raw material rises slowly together with the kiln wall as a whole under the action of friction. When it turns to the height, that is, when the angle formed between the surface of the raw material layer and the horizontal plane is equal to the stacking angle of the raw material, the raw material particles are under the action of gravity, Slide down along the material layer. Because the rotary kiln (rotary kiln) has an inclination, and when the raw material particles roll, they fall along a large direction of the inclination, so they move a long distance forward.

When the raw material moves in the kiln, the movement mode of raw material particles changes periodically, or is buried in the material layer and moves upward with the kiln, or falls down on the surface of the material layer. However, only when the raw material particles fall along the surface layer can it advance along the kiln length.

The movement of raw materials in the kiln will affect the residence time of raw materials in the kiln (i.e. heating time of raw materials); Filling coefficient of raw materials in the kiln (i.e. heating area of raw materials); The turnover of raw material particle size also affects the uniformity of raw materials (i.e. the surface temperature of combustion products and raw materials).

The influence of various motion conditions on the center angle, that is, the filling coefficient of raw material particles, must be paid attention to. If you want to maintain the filling factor in the kiln, you need to make the kiln speed and feeding speed match each other and maintain the proportion; This is also the process condition to improve the output and quality, stabilize the thermal system and overcome agglomeration.