Long distance belt conveyor system is already well known and rail, marine and competing pipeline position, and showing exceptional economy. The advantage of using a long-distance conveyor is that it can achieve continuous and efficient transportation with large volume; it can protect the material being transported because there is no or only a few transfer stations; it is suitable for any terrain, such as hilly and slope, especially suitable for valleys. Transport of the zone; easy to cross rivers, railways, highways, residential areas and industrial areas.
2. Overview of the development of long distance belt conveyor of the earliest overseas long distance belt conveyor is designed to be used in Spain Buke La apatite open in the plateau region of Western Sahara SHI Guang, the line up to 100km, the long 6. It consists of a belt conveyor with a bandwidth of 1000mm. It adopts ST3150 steel cord core tape with a belt speed of 4.5m/s and a capacity of 2000t/h. It was put into use in 1972 with a total investment of 200 million marks.
The 20km long-distance belt conveyor line in Chaanna Iron Mine, Australia consists of a long-distance belt conveyor with a length of 10.3km, a curve radius of 9km and an arc length of 4km, and a 10.1km long straight-line belt conveyor. . The system uses advanced roller manufacturing technology, horizontal turning technology and dynamic analysis technology.
The single-machine long-distance belt conveyor of the Yeshan limestone mine in Japan was transported from the Mengyin border to the long-distance belt conveyor of the domestic gravel in Bangladesh. The length of the single machine was 17.5km, which was put into use in 2005. China Shandong University of Science and Technology Co., Ltd. Ji Ning Ke large design Chaohu, Anhui coal power plant shipped long distance belt conveyor, single length of 11km, and put into use in 2006.
3. Driving method of long-distance belt conveyor The remarkable feature of long-distance belt conveyor is the longitudinal dimension of the conveyor. To overcome various resistances during operation, it must have sufficient driving capability. Therefore, most of the current length The driving method of the belt conveyor system is: a long-distance belt conveyor of a common structure. Its structure is the same as that of the ordinary belt conveyor, and its application range is the widest. It is generally believed that the maximum length of the single machine of this structure can reach 10-intermediate unit driving mode and five-string hanging roller group mode. Most of this structure is used on broadband conveyors. It has an intermediate drive with a wheelbase of 5 to 10 km, so the tension of the tape is reduced and the unit drive power of the conveyor is kept within a relatively economical range.
Roller drive method. In addition to driving at the head and tail, the conveyor of this type is driven by a driving roller equipped with a motor, so that the tension of the conveyor belt can be greatly reduced, and the length of the single machine can reach the wire rope traction belt conveyor. It uses a wire rope to drive and steer through large drive wheels. Since this structure separates the traction and carrying functions of the conventional conveyor belt, the length of the conveyor can be increased.
4. Reasonable selection of parameters for long-distance belt conveyors The design of belt conveyors is usually based on standard calculation methods. Practice has proved that the standard belt conveyor designed by the standard method has achieved good results, but for long-distance, high-speed conveyor system design, some problems that have not been paid attention to in the past for the design of ordinary belt conveyors are outstanding. .
4.1 The economical long-distance belt conveyor system of the conveyor system has a huge investment, and its investment amount is in the millions, tens of millions or even hundreds of millions of yuan. Therefore, how to carry out economic and rational design, saving engineering investment and reducing operating expenses is extremely Importantly, the method currently used is to properly arrange the idler spacing and reduce the number of idlers, thereby reducing the investment in the idler. The width of the idler is generally between 1. 0 and 1.5 m. The 20km conveyor system of the Caina Iron Mine in Australia has undergone economic analysis. The idler spacing of the roller conveyor is 2-3m. The spacing of the idler conveyors of the conveyor can also be arranged in unequal spacing. This not only ensures the operation requirements of the conveyor, reduces equipment investment, but also eliminates the resonance problem of the conveyor.
Reduce the transport resistance of the conveyor and reduce energy consumption to reduce the operating costs of the conveyor system. In order to reduce the resistance, it is necessary to improve the quality of the manufacture and installation of the rollers and to appropriately increase the diameter of the rollers. In the manufacture and installation of the 20km conveyor system in Chaona Iron Mine, Australia, a new molding tool and a tire are used, and the diameter is The 178mm large diameter roller reduces the friction coefficient of the linear conveyor to 0.00980 and reduces the tension of the conveyor belt. The reduction in belt tension has the potential to result in a lower strength grade conveyor belt during the design process, thereby reducing the belt investment. The reduction of the running resistance of the conveyor helps to reduce the tension of the conveyor belt. In addition, the multi-roller, multi-point drive and intermediate drive can effectively reduce the tension of the conveyor belt, but these driving methods have yet to be further improved.
Choose a reasonable drive system. In the design of the original long-distance belt conveyor, an excessively large motor was used to provide the necessary starting torque. Unfortunately, this powerful output has a very high torque, which causes the conveyor belt to be subjected to large oscillation waves. The use of large motors will make the conveyor starter more difficult.
4.2 Reasonable selection of the safety factor of the conveyor In the various design standards of the belt conveyor, in order to determine the reasonableness of the safety factor of the conveyor, the design calculation of the conveyor must use a lot of calculation coefficients, some of which are obtained through theoretical analysis. Some are based on design and usage experience and take into account common problems. This is suitable for conventional belt conveyors, but not for large, long-distance belt conveyor designs. The reason is that the small relative error brings a large absolute error to the long-distance transport opportunity.
A design parameter that has a great influence on the design of the conveyor, that is, the selection of the safety factor of the conveyor belt is an important issue for the study of the value. For the long-distance conveyor system, the cost of the conveyor belt accounts for 30% of the total cost of the conveyor. 35% If the safety factor is not properly selected, it will have a greater impact on the investment of the conveyor. Therefore, special attention and further analysis are required. Only by selecting the correct and reasonable safety factor can the designed belt conveyor be reasonable.
3 Correctly determine the conveyor volume of the conveyor In the current design data, the cross-sectional area of ​​the loose material on the tape is mainly determined by a tabular method. The problem is that, first, the factors considered are discrete. The groove angle and the stacking angle cannot be continuously changed, and interpolation is generally used to cause a certain error. Second, the calculation of repeated work is large. The section factor of the material needs to be selected repeatedly to match the section factor determined by the calculated bandwidth. Third, the tabular method is not conducive to computer program implementation. Therefore, in the design calculation of the long-distance belt conveyor, the cross-sectional area of ​​the loose material on the tape is correctly calculated by the formula method, and the material section coefficient of the belt conveyor is reasonably determined, and it is extremely important to determine the calculation productivity of the conveyor. . Based on these data, you can choose the optimal width and running speed of the tape to achieve better economic results.
Dynamic analysis of long-distance belt conveyor design. Establish the dynamic equation of the belt conveyor during start-up and shutdown, solve the changes of different points on the conveyor belt with time, and find out that the intense tension wave may cause The destruction, this is the dynamic analysis of the belt conveyor. The dynamic analysis technology not only analyzes the dynamic characteristics of the whole machine operation process, but more importantly, it is the high-tech of the world in the basic theory of its application and the use of modern advanced technology for system research. The use of dynamic analysis technology for design can not only achieve optimal design, reduce equipment investment costs, but also prevent the occurrence of operational accidents and improve the reliability of equipment operation. In foreign countries, Germany, the former Soviet Union, Australia, the United States, Poland, South Africa, Japan, etc., have conducted in-depth research on dynamic analysis techniques, and some have been applied in practical engineering. The methods and concepts of domestic dynamic design are still in the rigid mechanics stage, and have not really been applied to the design. Mastering the dynamic analysis technology will not only make a qualitative leap in the technical level of belt conveyors in China, but also bring huge economic benefits.
China's long-distance belt conveyor has greatly improved in terms of design, manufacturing level and production capacity, basically meeting the needs of national key projects, but we must also see the gap between us and foreign advanced levels. First of all, in terms of performance parameters, secondly, in terms of multiple varieties, the third is still in the research of dynamic design, high-speed vibration and soft-start (brake-drive) devices, which requires us to study, design and manufacture. Carry out scientific research, accelerate the development of new technologies and new products, and better serve the industrial development.
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