On-line repair of Common problems such as bearing Chamber, bearing position and Roller body Wear in Coal Vertical Mill

Date: 2019-07-01 Views:

1. General situation of equipment


Coal vertical mill, also known as medium speed coal mill, is suitable for grinding bituminous coal and lean coal and other medium hardness materials. It can be widely used in power, metallurgy, building materials, chemical and other industries, especially in blast furnace coal injection system, which needs a large number of bituminous coal. Because of its special technology and structure, the coal vertical mill has less dust and less noise in the production process, and the pulverized coal produced has high efficiency gradation and excellent combustion performance. The coal vertical mill has the advantages of simple process, compact equipment, stable pulverized coal fineness and uniform particle size.

The coal vertical mill is driven by motor and drives the mill disk to rotate through the planet reducer. The 2 / 4 rollers on the grinding disk rotate under the drive of the grinding disk. The raw coal coming in through the coal falling pipe is distributed on the grinding plate. Due to the action of hydraulic loading force, the large particle raw coal is crushed by extrusion between the grinding roller and the grinding disk. The small particle coal is crushed by the sliding friction produced by the relative movement of the roller and the grinding disk; while the raw coal is ground in the mill, the hot air (usually below 300 ℃) that passes into the vertical mill dries off the moisture of the raw coal to meet the requirements of the finished pulverized coal; the pulverized coal after grinding is transported into the separator through the primary air transportation. Separation. The qualified pulverized coal is transported to the pulverized coal bin, and the unqualified coarse pulverized coal is returned to the mill for re-grinding.

2. Common faults and causes analysis

2.1. Bearing chamber wear


The reason for the wear of the bearing chamber is that, in addition to the large stress, the main reason is that the metal characteristic of the material of the bearing chamber is determined, the metal is high in hardness, but poor in yield (which cannot be recovered after deformation), the impact resistance is poor, and the fatigue resistance is poor. So that the adhesion and wear, the fatigue wear, the fretting wear of the bearing outer ring and the bearing chamber can be easily caused.

2.2, bearing position wear


In the process of long-term operation of the equipment, the bearing temperature increases and bears the action of axial force and radial force at the same time, which leads to the matching clearance due to the interference size metal fatigue between the shaft and the bearing, which makes the relative motion between the bearing and the bearing position aggravate the wear. In addition, the quality problem of the bearing itself and the lubrication and maintenance are not in place in the process of use, which is also easy to cause bearing position wear.

2.3, roller body wear


The reason for the wear of grinding roll is generally due to the wear caused by the outer ring of roller skin for a long time, enterprises usually choose to surmount the roll sheet, and each surfacing welding will produce a slight deformation, the more times of surfacing welding, the thicker the surfacing thickness, the greater the deformation, so it is impossible to guarantee the arc of the circle, at the same time, there is also the influence of thermal stress, there is a small crack in the roll sheet, the more times, the thicker the surfacing thickness, the greater the deformation, so it is impossible to guarantee the roundness, at the same time, there is also the influence of thermal stress. The gap between the roll sheet and the roll body leads to the wear of the roll body, another reason is that in the process of operation and use of the equipment, due to the uneven material will appear radial impact on the grinding roll, resulting in large vibration is easy to bolt loosening, if not timely fastening bolts to maintain a good pre-tightening The force can easily lead to the insufficient pre-tightening force of the fastening bolt, which will lead to the matching gap between the body and the roller sheet, which will cause wear between the body and the roller sheet. of course, the failure of maintenance and repair is also the cause of this problem. The wear amount of the wear roller is not repaired in time, resulting in more and more wear until the roller surface is damaged and the equipment is shut down.

3. Comparison between traditional repair mode and field repair mode.

3.1, traditional repair model


in that case of the wear of the roll body of the grinding roll and the wear of the drive parts such as the bearing position and the bearing chamber, the traditional process is often used for machining after the repair welding, or the process of electroplating and the like is adopted, And the input manpower and material resources are relatively large. in addition, the thermal stress generated at the high temperature of the repair welding can not be completely eliminated, the material damage can be easily caused, cracks of the parts are caused, and the brush plating is limited by the thickness of the coating and is easy to be peeled off, and the above method is to repair the metal with the metal, and the matching relationship of the "hard-to-hard" cannot be changed, And can not reach 100% of the matching surface, and the comprehensive action of each force can be realized. Next, it will still cause another wear and tear.

3.2, site repair mode


Different repair schemes can be adopted according to different wear conditions. Polymer composites have good adhesion and mechanical properties, not only the strength and hardness of metals, but also their concessions. The application of polymer composites can be repaired without disassembly and machining, without the influence of welding thermal stress, and the repair thickness is not limited, which can ensure the repair accuracy and meet the installation requirements. The application technology of polymer composites can make the enterprise repair quickly and effectively in the first time, and the repair cost is lower than that of the traditional repair process. Generally, the amount of polymer composites can be calculated according to the wear amount, and then the repair cost can be calculated, and the repair cost can be effectively avoided. All kinds of time and economic losses, and the repair of polymer composites belongs to cold welding technology, there are no thermal stress and other problems, which can effectively avoid the secondary damage of the substrate.

4. Conclusion


Make full use of the comprehensive properties of composite materials, customize the targeted repair scheme and rigorous and scientific implementation repair scheme, change the traditional repair means of users, realize the repair difficult problems in the field for a short time, ensure the normal operation of the equipment, the process is simple, the cost is low, the production cost can be realized without large disassembly, and the reasonable control of production cost is realized. In addition to the above, Fushilan technical products have also been widely used in other equipment transmission parts of cement industry, such as wear, running leakage, heat exchange equipment cleaning and so on. It not only saves maintenance funds for enterprises, the most important thing is to save shutdown time for enterprises, but also save manpower and material resources.

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