Repair and maintenance of cement plant machinery and equipment

Mechanical equipment is an indispensable part of cement enterprises and an indispensable part of cement production. In the process of using equipment in the cement industry, various degrees of damage may occur from crushers, elevators, rotary kilns to cement machines. Among them, cement crushers are one of the most serious damages: the internal wear of the crusher is serious and it is difficult to operate normally, and the wear to a certain extent will also cause equipment damage. The damage of the crusher is very serious in all cement enterprises. Generally speaking, one crusher will be damaged for every 1 million tons of cement (usually cement crusher damage occurs in every 1 million tons of cement clinker); one rotary kiln will also be worn for every 1 million tons of cement. Such complex and very serious equipment damage is very rare in other industries. Of course, due to the particularity of the cement industry itself and the influence of various factors, a large number of mechanical equipment will be seriously damaged every year. Therefore, in-depth research on the equipment used in the cement industry has guiding significance for equipment replacement, maintenance and repair. This article introduces the problems, solutions and measures in the maintenance of cement machinery and equipment.

With the development of the times, the demand for mechanical equipment in the cement industry is growing. At present, in order to expand their scale, many enterprises have put more and more mechanical equipment into production, including various large-scale mechanical equipment and small and medium-sized mechanical equipment into different production lines. From large machines to small and medium-sized machines and equipment, production equipment is a very important part of the entire enterprise, so its maintenance work must be done well.

Although each cement enterprise has formulated a very complete maintenance system, there are still some small machines and equipment that do not meet the standards and cannot be effectively maintained. According to statistics, the number of cement machinery and equipment is large and is growing at a very fast rate every year. At present, from the perspective of the types of large-scale mechanical equipment, it has developed from the original common equipment to various new equipment, such as hydraulic presses, mixers and many other types of equipment.

From the perspective of specific operations, with the continuous development of the cement industry, the types of such new equipment are also increasing, but for most production enterprises, they simply use ordinary mechanical equipment to maintain and maintain them. The emergence of these equipment has greatly increased the difficulty of equipment repair and maintenance.

1. Problems in the maintenance of cement plant machinery and equipment

1.1 Wear

Wear refers to the wear or damage of a certain part of the equipment, mainly including cutting, friction and grinding. Cutting refers to the phenomenon that the cutting tool or tool rubs and breaks within a certain range. Among them, friction is mainly caused by friction; grinding refers to the phenomenon that parts are damaged by cutting. Therefore, in the production process, the operating procedures and process requirements must be carefully implemented to ensure that the cement machinery and equipment operate in good condition.

Wear includes two forms of wear: longitudinal and transverse. Transverse wear is caused by the gap between the inner blade and the outer blade, while longitudinal wear is caused by the equipment being unable to withstand the internal pressure. Longitudinal friction is caused by transverse torque; and transverse friction is caused by longitudinal torque. In daily work, we must conscientiously implement the maintenance system to ensure that the equipment is fully supervised and managed during operation, and do a good job in material performance analysis and testing. Abnormal phenomena found during use should be eliminated in time. During the maintenance process, the function of the parts can be improved by adjusting the material properties and dimensions of the parts. Only by ensuring that the mechanical equipment is in good working condition can it run more smoothly and efficiently.

1.2 Cracks

Due to the existence of certain working pressure, load and working temperature of mechanical equipment, a certain number of cracks will occur when the mechanical equipment is in high-speed operation. The most common defects are pores, burning and peeling. Porosity is caused by the internal pressure of the mechanical equipment during the start-up, operation and shutdown of cement equipment. Its main effect is the formation of cracks, but the loss caused by it is also very large. Generally, it needs to be eliminated through overhaul. Therefore, when cracks appear in cement machinery and equipment, the degree of damage must be taken seriously.

For example, when the cracks in cement machinery and equipment are close to the cylinder body and the cylinder head, its working condition and damage must be carefully observed in order to determine the best maintenance plan and take corresponding measures to deal with it. In addition, the cracks must be inspected and fixed in place with wooden sticks, wires or nails; the damaged parts must be repaired first, and those that cannot be repaired must not be used; newly purchased and unrepaired cement machinery and equipment must be installed according to the original design drawings; and cement equipment that is severely damaged and in large quantities must be overhauled. For cement equipment that has been used for a long time and is more serious (such as new cars), it must be repaired or replaced with new parts.

Before repairing, first check whether there is any crack formation; at the same time, carefully clean up dust and foreign objects such as debris in the cracks to prevent the cracks from continuing to expand; at the same time, the surface of the concrete equipment must be treated and carefully observed for cracks.

Usually, there are many ways to repair cracks in metal equipment, such as acetylene welding, laser cladding and other metal material remanufacturing technologies. In contrast, laser cladding is the best for metal repair, and can almost completely achieve the quality level of casting. The metallurgical bonding layer formed on the workpiece after laser cladding repair can be 5-10 times stronger than the original part, and has excellent properties such as wear resistance, high temperature resistance and corrosion resistance.

1.3 Jamming

In cement machinery and equipment, damage to bearings and cylinder walls can cause poor lubrication and other phenomena. During operation, these wear and tear are fatal. Therefore, the maintenance of mechanical equipment should strengthen the management of lubricating oil and grease, and replace failed parts and lubricants in leaking oil channels in a timely manner. If you replace unqualified lubricating oil and grease, you must strictly follow the instruction manual or use them reasonably during operation; if the wear is serious, you should repair or replace new oil and bearings in time according to the characteristics of the fault. At the same time, you should strengthen the inspection of the wear condition of bearings and cylinders, and repair and replace them immediately once abnormalities are found. If there is a serious wear on the shaft end face or other reasons that cause unreasonable bearing clearance, you should adjust it in time to ensure the lubrication effect, and you should also strictly follow the instruction manual.

If the equipment is jammed, it needs to be shut down for inspection and maintenance; when replacing parts, it must be shut down for inspection and maintenance before restarting; if it needs to be shut down for inspection and maintenance immediately after inspection and maintenance, it must be repaired and replaced after restoring the original state. Therefore, if cement machinery and equipment is stuck during use, it should be repaired and replaced in time to resume operation; once the equipment is found to have a fault, it should be eliminated in time to avoid harm to the normal production of cement enterprises. For this problem, it is necessary to conduct detailed analysis and research to ensure that the cement production cycle can be effectively shortened, production costs can be reduced, and the quality of cement products can be effectively guaranteed. Of course, in the specific maintenance work, more maintenance methods and measures can be used to improve the effect.

1.4 Deformation

If the equipment is deformed or the degree of damage is very serious, it will have a certain impact on the development of the cement industry. The main reasons for equipment deformation are: ① Loosening of bolts and nuts. ② Incorrect installation of bolts and nuts. ③ Deformation of cylinders and pistons. ④ Deformation of mechanical parts. ⑤ Excessive bearing load or bearing failure. ⑥ Deformation of the cylinder, piston and its connecting pin. ⑦ Excessive spring pressure causes deformation. ⑧ Bearing overload or bearing failure.

Therefore, it is necessary to check each part to eliminate the cause of equipment deformation.
Equipment deformation may cause the equipment to fail to operate normally, resulting in the equipment not being able to fully play its role or even causing equipment failure. When carrying out maintenance work, the following measures can be taken:
(1) Check and deal with deformation problems in a timely manner. Before inspection, analyze the deformation problem and propose corresponding preventive measures and methods.
(2) Eliminate nuts that do not meet standard requirements in the equipment in a timely manner.
(3) Increase the maintenance intensity and speed of parts that may fail.
(4) Do a good job of cleaning.
1.5 Corrosion
The corrosion of cement plant machinery and equipment is mainly caused by the chemical properties of the metal itself and the oxygen, carbon dioxide and water vapor generated in the environment. Among them, water vapor is the most serious corrosion to metal. Under water vapor conditions, metal atoms will diffuse into the surrounding air. In cement machinery, water vapor will cause local high-temperature heating and the formation of an oxide film on the metal surface. After oxidation, the oxide film will cause defects, such as cracks, peeling, carbide loss, etc.
Because water and oxygen have different degrees of absorption and selectivity to metal corrosion. When oxygen is at a high temperature, water and metal react chemically to produce hydrogen, which causes serious failures, which is called acidic water damage or alkaline water damage; when oxygen and metal react chemically, alkaline water damage is produced; when water and oxygen react chemically, corrosive products are formed; when water and oxygen have an explosive mixture, it is oxidative corrosion damage; when water and oxygen cannot react chemically well, it is acidic corrosion damage. If the electric heating wire selected in the cement equipment fails (such as the temperature is too high or too low), the thermochemical reaction it produces will destroy the matrix alloy layer inside the metal and make it ineffective.

Since too high or too low temperature can cause pores and cracks in the metal in the molten steel and cause corrosion, during the overhaul and improvement of technical processes, electric heating wires with good corrosion resistance must be selected to enhance the corrosion resistance of mechanical equipment.

In this case, we can also use laser cladding technology to deal with this problem. At present, the best solution for metal repair and corrosion resistance is laser cladding. The new corrosion-resistant alloy powder and the substrate form a new metallurgical bonding layer during the laser cladding process, which is wear-resistant and corrosion-resistant, which is an effect that metal spray coatings cannot achieve.

2 Suggestions on the repair and maintenance of cement plant machinery and equipment

2.1 Strengthen the construction of the maintenance team and improve the overall quality of maintenance personnel

The maintenance management of cement machinery and equipment is a huge system project, which requires maintenance personnel to have high maintenance skills and rich maintenance experience. At the same time, the training of maintenance personnel is also a difficult task. Due to the high requirements for maintenance technology, maintenance personnel must have solid maintenance theoretical knowledge and proficient maintenance skills, and have a fairly high level of maintenance management. Cement machinery and equipment maintenance personnel should have the following characteristics:
(1) Maintenance personnel must be familiar with mechanical equipment maintenance technology and master the core technology of mechanical equipment maintenance management.
(2) Have a high sense of professionalism and responsibility, master professional technical knowledge and be able to apply it to actual maintenance management work.
(3) Have strong professional knowledge and technical ability, be able to endure hardships, be willing to contribute, pursue perfection and have a spirit of professionalism.
(4) Master various equipment maintenance knowledge and skills, and be able to operate and handle complex cases independently.

Therefore, the maintenance management level determines the position of enterprise maintenance management in the industry and its future development direction to a certain extent. Improving the comprehensive quality of maintenance personnel means improving their familiarity with equipment performance, improving their comprehensive maintenance capabilities, and improving their operation and maintenance levels. Maintenance personnel should constantly learn new knowledge and new technologies, constantly improve their working methods, constantly improve their business quality, master equipment performance, maintenance theory, working principles, on-site working conditions and other aspects of knowledge, and constantly update their concepts. Maintenance personnel will encounter many new problems in the process of mechanical technical work. In order to ensure the quality of maintenance, maintenance personnel must master certain maintenance theory knowledge and skills. Maintenance personnel should establish a lifelong learning concept, insist on applying what they have learned, and constantly improve their mastery of mechanical equipment maintenance knowledge and comprehensive maintenance capabilities.

2.2 Pay attention to the operating environment of cement machinery and equipment

Construction management personnel should manage the operating environment of mechanical equipment to a certain extent. The installation location of cement machinery should be optimized according to the specific equipment conditions. In terms of environmental management, special personnel should be sent regularly to clean the dust on the surface of cement to ensure the normal operation of the machine. In addition, in daily machinery and equipment, workers should be reminded to be careful to prevent dust from splashing onto the machine when using the machine to avoid damage to the machine.

2.3 Increase the repair efforts of key equipment parts

In order to ensure the normal use of cement machinery and equipment, in the maintenance work, the maintenance ideas and methods should be combined, and the key parts of the machine should be repaired. For example, the most common rolling bearing of the rolling mill should be checked frequently during maintenance. The temperature and vibration of the bearing should be checked frequently. Large roller presses can be tested by adding various computer technologies and intelligent systems, so that the fault problem can be accurately judged and the working status of the main parts can be clearly understood. The failure inspection of the converter is also very critical. Its work is to check the key parts of the drum and wheel, and use related detection devices such as tire gap meters and infrared thermometers to effectively check the temperature and gap in the furnace. Efficient maintenance of key components plays an important role in improving the operating quality of the entire device.

2.4 Targeted maintenance combined with the cause of the fault

The maintenance of cement machinery and equipment is relatively complex, which requires finding the root cause of the problem and conducting targeted maintenance to improve the quality of the entire maintenance work. During the inspection, the internal factors of the machine should be checked to check whether the internal structure of the machine is reasonable, whether the material selection of the components is scientific, and whether the manufacturing process meets the requirements. These will affect the working quality of the machine. Therefore, it is necessary to deal with it from the source to achieve quality assurance of product assembly and production process. The external reasons are due to factors such as the application environment, operating load, installation and commissioning of the equipment, as well as corrosion and dust, which will have an adverse effect on the work of the machine. Therefore, environmental protection issues should be paid attention to during maintenance. During the maintenance period, the relevant departments should keep records of the maintenance work to lay a good foundation for the implementation of future maintenance work.

2.5 Optimize the maintenance service system and improve the maintenance service capabilities

To improve maintenance efficiency, maintenance resources must be reasonably allocated and utilized. In terms of service system, different forms or levels of service items are mainly adopted for different manufacturers and different models of equipment. For equipment maintenance, attention should be paid to the construction of maintenance service teams, especially to strengthen the construction of maintenance teams and technical training, and regularly assess the maintenance teams; at the same time, efforts should be made to build service systems to improve the quality of maintenance services.

In terms of maintenance resource integration, the maintenance service system should be integrated with other production maintenance service systems. In terms of after-sales guarantee, cement companies also need to establish a complete after-sales service system to improve their after-sales service capabilities. Due to the high technical content and high requirements of the cement industry, with the continuous emergence of new technologies and new processes, as well as the continuous improvement of production and management technology levels, cement companies need to continue to learn how to ensure that after-sales equipment can better serve the company.

3 Conclusion

The cement industry has been developed in my country for decades, and the maintenance of cement machinery and equipment has gradually matured. In the process of work, cement plants need to attach great importance to the maintenance of mechanical vehicles. Different maintenance plans need to be adopted for different types of mechanical vehicles. Only in this way can the mechanical vehicles be ensured to operate more efficiently, stably and safely. And in the maintenance work, it is necessary to pay attention to the maintenance of equipment parts. In order to ensure that the mechanical equipment has good quality during the normal operation life, it is also necessary to perform regular maintenance work on the mechanical equipment. A special maintenance plan needs to be formulated for each mechanical vehicle to ensure the normal operation of the mechanical equipment and its maximum efficiency. In addition, the maintenance of mechanical vehicle parts and components should be strengthened to ensure that the maximum efficiency can be better exerted in the maintenance of concrete mechanical vehicles.

For friends who are preparing to build a new cement plant, energy is a very important issue. If the natural gas or associated gas in your area is very rich, you can use local materials and use gas generators to generate electricity to power the factory production, which will reduce the overall cost a lot.