In industrial production, Centrifuge Basically, it is a post-treatment equipment, mainly used for dehydration, concentration, separation, clarification, purification, solid particle classification and other technological processes. It has developed with the development of various industrial departments. For example, after the industrial revolution in the 18th century, with the rapid development of the textile industry, the cotton cloth dehydrator appeared in 1836. In 1877, in order to meet the needs of the cheese processing industry, a separator for separating milk was invented. After entering the 20th century, with the development of comprehensive utilization of petroleum, it is required to remove water, solid impurities, tar like materials, etc., so that heavy oil can be used as fuel oil. In the 1950s, a disc piston slag extractor with automatic slag removal was successfully developed, and by the 1960s, it had developed into a complete series of products. With the needs of modern environmental protection and the development of three wastes treatment, the requirements for industrial wastewater and sludge dewatering are very high, so Horizontal spiral discharge sedimentation centrifuge The disc centrifuge and the tripod lower discharge sedimentation centrifuge have further developed, especially the horizontal spiral discharge sedimentation centrifuge. Today, in the separation equipment for the production of synthetic plastics (PVC, polypropylene) and synthetic fibers (polyethylene terephthalate), Screw centrifuge It has become one of the key equipment.
The first screw centrifuge with real modern practical value in China was manufactured in 1954. Due to its unique characteristics of continuous operation, large processing capacity, less power consumption per unit output and strong adaptability, it has developed rapidly. During more than 40 years of development, its structure, performance and parameters have changed greatly, separation quality and production capacity have been continuously improved, and its application scope has been wider, It has always played an important role in the field of centrifuges. At various international exhibitions, all kinds of spiral centrifuges are the most attractive models among the centrifuges on display, with good prospects for development.
Since the end of 1970s, China has introduced screw centrifuges, which are used to produce Horizontal screw centrifuge It is imitated. The decanter centrifuge is a key scientific and technological project of the original Ministry of Chemical Industry during the "Seventh Five Year Plan" period. In 1989, Nanjing Lvzhou Machinery Factory copied the ALFANx42o large cone angle (20) centrifuge (L201) for the separation of corn gluten, and made a prototype in 1992; Since then, Chongqing Jiangbei Machinery Factory, PLA 4819 Factory and Jinhua Railway Machinery Factory have developed a series of spiral discharge sedimentation centrifuges and successfully applied them to production practice. But on the whole, China is still far behind the industrial developed countries. With the development of modern industrial civilization and human attention to the environment and sustainable development strategy, good separation effect, low vibration and low noise become important conditions for centrifuge to be accepted by the market. This requires the centrifuge to have good dynamic characteristics. In general, dynamic characteristics include critical speed, unbalance response and stability. The parameter selection and optimization of horizontal screw centrifuge is the first step to improve the dynamic characteristics of horizontal screw centrifuge.
In order to improve the performance of the spiral discharge sedimentation centrifuge, people tackle the common problems of the centrifuge and carry out finite element analysis on the main components. Some achievements have been made. Mainly: Gu Wei, master of Beijing University of Chemical Technology, applied the finite element analysis software ANSYS to establish a parametric three-dimensional finite element model of the screw conveyor, carried out structural static analysis, obtained the stress field and displacement field of the screw conveyor under various load conditions, and checked the stress intensity of the screw conveyor with reference to the analysis and design method of pressure vessels, The radial displacement of helical blades was investigated. It lays a foundation for structural optimization design.
Cai Xianxin, senior engineer of China Aviation Industry, proposed the method of combining shell element and ring element to conduct elastic-plastic analysis on integral centrifugal impeller with splitter blade. The blade is simulated by shell element, and the wheel body is simulated by axisymmetric ring element. The double coordination condition is approximately satisfied at the junction of the impeller and the wheel body. The results show that this method has high precision and good time saving.

Yuan Fucai, an engineer from the School of Mechanical and Electrical Engineering of Harbin Engineering University, analyzed the force on the materials in the horizontal screw centrifuge, derived the calculation formula of the screw pushing torque, and used it as the objective function, and took the process requirements as the constraint condition, used the complex optimization method in the optimization design theory to comprehensively analyze and quantitatively select the parameters of the wL-600 horizontal screw centrifuge, The C program for optimal solution is compiled, which makes the determination of parameters simple, convenient and reasonable.
Shen Jin of China Academy of Agricultural Engineering Research and Design, Du Linghan and Xu Qun of Shanghai Centrifuge Research Institute, general horizontal type for LW-400 Spiral sedimentation centrifuge The directional modification was carried out: several longitudinal blades were added on the inner spiral, and the working surface of the inner spiral was sprayed with cemented carbide. After the improvement, the separation effect and the service life of the whole machine are obviously improved.
Li Fuming, from Sichuan Jiangbei Machinery Factory, established the polar coordinate equation of the constant velocity spiral line according to the shape characteristics of the conical spiral blade of the spiral discharge centrifuge. Through the production and manufacturing of such models of centrifuges as wL-200A, wL-350, wL355xl420-N, wL-450 and wL-600, it is proved that the expansion calculation method is superior to the graphic expansion method in solving the expansion blanking diagram of conical spiral blades, which effectively meets the reliability and use performance requirements of the spiral conveyor manufacturing process.
Liu Youhong, Department of Machinery, Jiangsu Institute of Petroleum and Chemical Technology, proposed to analyze the whole centrifuge drum with two-dimensional three-dimensional unit, and carried out finite element calculation on the large diameter drum of a domestic horizontal scraper centrifuge. The results show that the stress level in the bottom of the drum and the baffle plate is low; The stress level in the rotating cylinder is high, and there is stress concentration around the opening. The maximum virtual elastic stress is far greater than the yield limit of the material.
Dong Junhua, Liu Zhongming and Fan Deshun from the School of Mechanical and Electrical Engineering of Beijing University of Chemical Technology simplified the axisymmetric model of the drum into a two-dimensional model. The two-dimensional finite element model of the double cone angle drum of the large horizontal screw centrifuge was established by using the ANSYS finite element software.
Yan Chunmin, senior engineer of Nanjing Lvzhou Machinery Factory Horizontal Screw Centrifuge Design Institute, qualitatively analyzed the relationship between the sediment condition of horizontal screw centrifuge and its cone angle knife of drum, inclination B of screw conveyor blade, screw pitch of blade, radius of liquid pool and differential speed An, and expounded the design idea of improving the slag conveying condition of horizontal screw centrifuge.
Dong Shuifu, Yang Huitong and Lin Weiqing from Jiangsu Research Institute of Chemical Machinery discussed the influence of feed concentration, separation factor, overflow radius and other parameters on kaolin classification performance of WL-400 centrifuge. Wang Yanhua, Fang Tunan and Wang Tingnan from East China University of Science and Technology introduced the application of horizontal spiral discharge sedimentation centrifuge in the chemical fiber grade, focusing on the influence of feed concentration, feed speed, rotating speed, baffle size, differential speed and other parameters on the grade, and analyzed the reasons for the influence of various parameters on the grade. Their research provides a reference for finding the best operating parameters and applications of centrifuges.
Liu Jinrong, Oilfield Equipment Research Department of Lanzhou Petroleum Machinery Research Institute, and Wang Tianlin, Drilling Technology Research Institute of Shengli Petroleum Administration Bureau, tested the vibration performance of the spiral sedimentation centrifuge, and obtained the relationship between the effective value of the centrifuge vibration acceleration and the processing capacity of the centrifuge, the rotating speed of the drum, and the viscosity and density of the suspension, as well as the natural frequency of the test centrifuge.
Dong Jin, the Third Petroleum Plant of Fushun Petrochemical Company, applied the domestic LWD-430 horizontal spiral sedimentation centrifuge for sludge dewatering process, supplemented with high-efficiency organic flocculant. The test run proves that this process has a remarkable dewatering effect, which can dewater the sludge with a moisture content of 9.8% - 98.5% to 75% - 78%, and the separating liquid has no obvious impact on the sewage treatment device, eliminating the serious problem of secondary pollution caused by sludge.
It can be seen that the structural optimization of centrifugal mechanism can effectively improve the working performance and bring good economic benefits. However, people mostly study the screw conveyor, drum and other parts separately, but seldom study the whole screw drum group.
Centrifuge screw drum group has a complex structure, the force is related to the material, and changes greatly. The traditional analytical method is used to establish the screw drum group multi rigid body system. The dynamic equation and constraint equation of the analytical mechanics method represented by Newton Euler equation or Lagrange equation are analyzed to find out the parameters that affect the dynamic characteristics, the natural frequency and vibration mode of the structure.

It is not ideal to establish the vibration equation with a certain degree of freedom and obtain the phase to reduce the vibration through numerical analysis. As the spiral drum group is a multi-body system composed of rigid body and flexibility, it is also subject to the force generated by the entry of materials when working, and the constraints are complex. It is difficult to establish and solve the equations, which can only be idealized, and the results can not truly reflect the working characteristics of the centrifuge. And because there are many factors affecting the technical parameters, it is very difficult to calculate the complexity of the centrifugal separation effect one by one. Therefore, it is difficult to meet the requirements of good separation effect and low noise when selecting various parameters; According to qualitative analysis, select parameters based on experience, and then rely on the results of small or medium-sized laboratory tests for analog amplification. This method, which is characterized by experience, trial and error, static and qualitative, as well as the continuous cycle of optimization process of "design one prototype, test one modification", is troublesome and costly.

The research on the dynamic characteristics of spiral drum group should consider not only its rigid body motion, but also its flexible body motion. Both multi-body dynamics analysis and finite element analysis are not easy to solve such problems. With the development of high-performance computers and large-scale application software, especially Pr/ E and MSc The application of Visual Nastran, which combines the finite element method with multi-body system simulation to solve the dynamics problem of the spiral drum group, is an innovative method for the research of horizontal spiral centrifuge.

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