Rotary kiln information about structural characteristics and working principle

Rotary kiln concept

Rotary kiln is also called rotary calcining kiln, commonly known as rotary kiln, which belongs to the category of building materials equipment. In many production industries such as building materials, metallurgy, chemical industry, environmental protection, etc., rotary circular machines are widely used for mechanical, physical or chemical treatment of solid materials. Rotary kiln can be divided into cement kiln, metallurgical chemical kiln and lime kiln according to different materials.

Structural characteristics of rotory dryer machine 

1. Rotary kiln supporting roller device: The supporting roller device is divided into two types: with and without a retaining roller. A set of supporting roller devices includes two supporting roller groups and a supporting roller base. Some supporting roller devices also have a supporting roller device. The wheel set, the supporting wheel set includes the supporting wheel, the supporting wheel shaft and the supporting wheel bearing, etc. The supporting roller is the load-bearing device of the rotary kiln, so the tug is a part that works under heavy load conditions. The supporting roller of the rotary kiln is mainly composed of the tug, the shaft and the retaining ring on the shaft. When the supporting roller moves in series due to the axial movement of the kiln body, the supporting roller can be supported on the top of the bronze bearing bush by the retaining ring.

2. Rotary kiln retaining wheel: The retaining wheel is installed on both sides of the rotary kiln rolling ring, mainly to indicate and properly prevent the axial movement of the cylinder. There are generally only one pair of retaining wheels, which are clamped on both sides of the rolling ring, and the distance from the two sides of the rolling ring is determined by the allowable axial movement distance of the cylinder to ensure the contact between the rotary kiln rolling ring and the supporting roller, and can also be used in the rotary kiln cylinder. Both ends act as seals.

3. Rotary kiln rolling ring: In order to prevent the rolling ring from falling off when the cylinder body is heated and axially expanded and stretched and axially moved, the surface width of the rotary kiln supporting roller should be wider than the rolling ring by 10-80mm.

4. Large gear of rotary kiln: There is a large gear on the cylinder of the mechanical transmission rotary kiln, which is generally located in the middle of the rotary kiln. The large gear is driven by the pinion located on the civil foundation of the transmission device. The general general structural form of mechanical transmission is that the main drive motor drives the main reducer, and then drives a pair of open gears. After multiple speed changes, the small gear connected to the large ring gear can be driven at the required speed, so that the large ring gear drives The rotation of the kiln body can meet the requirements of the process operation.

5. Rotary kiln coupling: The auxiliary drive motor is connected to the high-speed input shaft of the reducer after passing through a set of reduction devices, and the main transmission motor and the reducer are directly connected by a coupling. In addition to the low-speed output shaft of the main reducer, both ends of the high-speed input shaft are connected to a motor, one is the main drive and the other is the auxiliary drive motor.

6. Rotary kiln bearings: Rotary kiln bearings are generally sliding bearings with thin oil lubrication and water cooling pipes. Considering the possible bending of the cylinder, the sudden increase of the load on the supporting roller and the harsh working environment of the supporting roller, the rotating The bearings of the kiln must have a large safety factor, good lubrication, sealing and water cooling. In order to adjust the axial movement of the cylinder, the supporting roller bearing of the rotary kiln must be made to be adjustable and movable, so that the supporting roller can move in the horizontal direction.

The working principle of used rotary cement kiln

Cement firing equipment includes shaft kiln, wet rotary kiln (rotary kiln), ordinary hollow dry kiln, Li Boer kiln, preheater kiln (SP) and the new type of dry rotary kiln (rotary kiln) commonly used at present.

The rotary kiln equipment (rotary kiln) is a cylindrical object with a certain slope, the slope is 3-3.5%, and the rotation of the kiln promotes the stirring of the materials in the rotary kiln (rotary kiln), so that the materials are mixed and contacted with each other. to react. The coal injection combustion at the kiln head produces a large amount of heat, and the heat is transferred to the material by means of flame radiation, hot gas convection, and kiln brick (kiln skin) conduction. The material moves forward in the kiln depending on the inclination of the kiln cylinder and the rotation of the kiln.

1. Rotary kiln equipment (rotary kiln) is a combustion equipment on the one hand, in which pulverized coal is burned to generate heat; at the same time, it is also a heat transfer equipment, and 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 the fuel combustion can be transferred to the raw materials in time during the time the raw materials pass through the rotary kiln (rotary kiln), which has reached high yield, high quality and low consumption. the goal of.

2. The movement of raw material particles in the rotary kiln equipment (rotary kiln) is relatively complicated. If it is assumed that the raw material particles do not slide 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 slowly rises together with the kiln wall as a whole under the action of friction, and when it turns to a certain height When the angle formed by the surface of the raw material layer and the horizontal plane is equal to the accumulation angle of the raw material, the raw material particles will slide down along the material layer under the action of gravity. Since the rotary kiln (rotary kiln) has a certain inclination, when the raw material particles roll, they fall in the direction of the maximum inclination, so they move forward a certain distance. When the raw material moves in the kiln, the movement mode of the raw material particles changes periodically, or it is buried in the material layer and moves upward together with the kiln, or it falls on the surface of the material layer. But only as the raw material particles fall along the surface layer, it can proceed along the length of the kiln.

The movement of the raw material in the kiln will affect the residence time of the raw material in the kiln (that is, the heating time of the raw material); the filling coefficient of the raw material in the kiln (that is, the heating area of the raw material); the turning of the raw material particle size will also affect the uniformity of the raw material (that is, affecting the surface temperature of combustion products and raw materials). The influence of various motion conditions on the central angle, that is, the influence on the filling factor of the raw material particles, must be paid attention to. If you want to maintain a certain filling coefficient in the kiln, you need to make the kiln speed and feeding speed match each other and maintain a certain ratio; this is also the process conditions for improving output, quality, stabilizing the thermal system, and overcoming agglomeration.