Current Status of Vertical Grinding Technology in China and Problems Needing Attention in Selection
I. Overview
Since the development of the first vertical mill in Germany in the 1920s, it has overcome many of the shortcomings of the ball mill grinding mechanism with its unique grinding principle. Because the vertical mill uses the material bed grinding principle to grind the material, it has high grinding efficiency, low power consumption (20-30% energy saving than the ball mill), large drying capacity, large grain size allowed for grinding, and grinding process. Simple, small footprint, low civil construction cost, low noise, low wear, long life, easy operation, etc., attracting many powder engineering researchers equipment manufacturers all over the world. After nearly a century of development, vertical grinding technology has been very mature. Since the 1960s, with the birth of kiln decomposition technology and the development of large-scale, vertical mill foreign cement industry has been widely used, and its technical level has been further improved. More than ten companies at home and abroad have successively developed various types of vertical mills, all of which have achieved success.
Germany LOESCHE company developed LM vertical mill, Pfeiffer company developed MPS vertical mill, KruppPolysius company developed RM vertical mill, Denmark FLSmith company developed Atox vertical mill; Japan Ube company produced German LOESCHE company technology, produced UB -LM vertical mill;
Germany LOESCHE is currently manufacturing LM69.40 vertical mill, the main engine installed capacity is 7000Kw, the output can reach 1200 tons / hour, will be used in India and Nissan 10,000 tons clinker cement production line supporting grinding cement raw materials, the world's largest vertical mill.
Second, at present, several domestic large-scale vertical mills are available for domestic use and their main features
1.HRM vertical mill
HRM Vertical Mill Hefei Cement Research and Design Institute can be widely used in building materials, metallurgy, electric power, chemical industry, non-mine industry and other industries to grind various non-metallic materials, high-efficiency energy-saving drying and grinding equipment, the first HRM1250 vertical grinding In 1989, it was used in the cement factory of Mengcheng County, Anhui Province. In 1993, it passed the ministerial technical appraisal. In 1996, it won the second prize of scientific and technological progress in the building materials industry. The HRM vertical grinding disc is disc-shaped and the grinding roller is tire-shaped, which constitutes a reasonable grinding area, high grinding efficiency and low power consumption. The grinding roller can be turned out of the machine for maintenance. The roller sleeve can be used for turning over, which can prolong the service life. It can prevent the roller sleeve and the disc liner from directly contacting the limit device, which can avoid the violent vibration caused by the material break during the operation of the mill.
The roller bearing is forcedly lubricated by thin oil circulation and naturally sealed outside the machine. The bearing can be well lubricated and cooled, which greatly improves the service life of the bearing. The horizontal axis of the grinding roller is supported by rolling bearings and is maintenance-free. The pressurized cylinder is designed to quickly split the structure, which is very convenient for maintenance and overhaul. HRM4800 Vertical Grinding Each grinding roller is pressurized with a double cylinder, which reduces the cylinder diameter and increases the reliability of the cylinder. The separator is a dynamic-static high-efficiency separator with high powder selection efficiency and low resistance.
Up to now, HRM vertical mills have produced more than 600 sets and are growing at a rapid rate of 100 sets per year. It can be used not only for grinding cement raw materials, but also for grinding non-metallic materials such as coal, slag and non-mine. It has four series of cement raw material grinding, coal grinding, slag/cement grinding non-mine super fine grinding, 30 A variety of products, widely used in building materials, chemicals, electricity, metallurgy, non-mineral and other industries, and exported to Pakistan, Turkey, Egypt, India, Vietnam, Algeria, United Arab Emirates and other countries.
In October 2008, the country's largest vertical mill - HRM4800 vertical mill Zhejiang Hushan Group 5000 tons / day cement clinker production line put into operation, the grinding area of ​​the equipment is Ø4800, the outer diameter of the grinding area is Ø5600, the outer diameter of the grinding disc For Ø6100. Under the condition that the grinding index of the grinding material is 15.2 kWh/t hard-wearing material, the output still reaches 450 t/h, and the system grinding power consumption is 13.5 kWh/t. The main technical and economic indicators have reached the advanced level of international similar products.
HRM4800 vertical mill is designed according to the grinding raw material with the daily production of 5000~7000 tons of cement clinker production line. It only needs different speed reducer and motor to meet the needs of different cement production lines. At present, China's largest vertical mill.
2.TRM vertical mill and LGM vertical mill
The TRM vertical mill LGM vertical mill structure is the same as the LM vertical mill. The grinding disc is a flat disc and the grinding roller is a frustum type. The grinding roller can be turned out of the machine for maintenance. The separator is also a dynamic-static separator. The main features are the same as the German LOESCHE mill.
TRM vertical mill Tianjin Cement Industry Design and Research Institute developed vertical mill, which features faster grinding disc speed. Therefore, compared with other types of vertical mills, under the same conditions, the output is higher, and under the same capacity conditions, the specifications are better. Small, the device is light in weight and can be adapted to the external circulation system of the wind sweeping part. The TRM53.40 vertical mill with the daily production of 5,000 tons of cement clinker production line was put into operation in September 2008, and reached various technical and economic indicators.
3.MLS (MPS) vertical mill
MPS vertical mill Shenyang Heavy Machinery Factory introduced German extraordinary company to introduce vertical grinding technology from West Germany PFEIFFER company in December 1985. The contract stipulates the transfer of all design and manufacturing inspection techniques for eight types of products, as well as the complete laboratory equipment for MPS mills for test selection to meet the needs of 700t/d, 1000t/d, 2000t/d cement plants.
As the contract has expired, Shenyang Heavy Machinery Factory changed the vertical mill product to MLS vertical mill, and developed and designed MLS3626, MLS3626 reinforced and MLS4531 raw material vertical mills, respectively, with 2500t/d, 3000t/d5000t/ d cement clinker production line supporting grinding raw materials. The vertical grinding and grinding area is a ring groove type, the grinding roller is a tire type, and the roller sleeve is a split type structure. Each grinding machine has three grinding rolls, and the hydraulic cylinder presses the three grinding rolls through a pressure frame.
Third, the selection of vertical grinding should pay attention to several problems
1. Through several sets of 5000t/d cement clinker production line, the large vertical mill is equipped with domestic reducer. The domestic vertical mill and reducer design and manufacturing technology are basically mature, which can meet the needs of 5000t/d cement clinker production line. The delivery period is shorter and the price is lower. Imported vertical mills have long lead times and high prices (more than 50% more expensive than domestic reducers), and domestically imported vertical mill reducers have been used for 3 to 5 years, with frequent maintenance cycles and high replacement parts costs. It is difficult to arrive in time, and the whole production line has been shut down for several months. Therefore, it is recommended that the domestic production line prefer the domestic vertical mill and reducer.
2. When choosing the domestic vertical mill, pay attention to whether the structure is reasonable, whether the maintenance and repair are convenient, whether the technical and economic indicators are advanced, whether the after-sales service is guaranteed, whether the operation cost is low, and whether the supplier has strong R&D capability and technical update. Ability and so on. These require users to conduct in-depth and meticulous research, not just to look at enterprise-scale advertising.
3. Do not be superstitious about imported parts. Importing foreign famous brand parts is beneficial to improve equipment reliability, but it should also be comprehensively analyzed from maintenance, maintenance, parts guarantee and cost. It is worthy to import hydraulic components, cylinder seals and other low value, easy to replace parts. . For expensive parts such as main reducers and roller bearings, it is recommended to use domestic equipment.
One of the reasons: if the vertical grinding roller bearing with the Nissan 2500 ton cement clinker production line is imported bearing, compared with the domestic bearing, the added cost is enough to buy a complete grinding roller assembly as a spare part; Nissan 5000 tons of cement clinker production line supporting raw materials vertical mill using imported main reducer, compared with the use of domestic reducer, the added cost is enough to buy a complete reducer assembly as a spare part;
The second reason: in the past few years, imported and Nissan 2,500 tons, 5,000 tons of production line supporting raw materials vertical grinding machine reducer, a large proportion of faults, maintenance costs are very high, and the entire production line is suspended for a long time, resulting in losses Very large, some imported reducers have to rely on domestic reducer manufacturers to repair.
4. Do not stick to the kiln and one grinding production line equipped mode, it should be adapted to local conditions. The kiln-milling production line has simple process and few process steps, but the mill has large specifications and difficult transportation. For the inconvenient transportation area, it is recommended to select a kiln two-grinding process plan. This kind of process has more than 30 production lines in China, and the technology is also very mature. The equipment investment is low, the supply period is short, the equipment maintenance is easy, and one peak can be stopped at the peak of power consumption, and it is beneficial to improve the operation rate of the kiln system.
Two 5000t/d production lines of a large-scale cement group company's daily production capacity of 10,000 tons of cement clinker production base use imported single vertical mill domestically produced two HRM3400 vertical mill grinding materials, and the results of two domestic vertical mill system raw material processing The power consumption is 11% lower than that of the imported single vertical mill system. Therefore, the two-mill-kiln system is not necessarily more expensive than the one-mill-kiln system.
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