Analysis of the Screening Effect of Fine Coal by Flip Flow Screen and Banana Screen
Introduction
Flip Flow Screen and Banana Screen, as two common screening devices, exhibit different effects in the screening process of fine coal. The Flip Flow Screen performs a slack and taut motion on the screen surface, effectively enhancing the screening efficiency. Particularly for the permeability of fine coal, the alternating tension and relaxation of the screen surface of the Flip Flow Screen cause better loosening and stratification of coal particles on the screen surface, thereby improving the screening accuracy and output of fine coal. The screen surface of the Banana Screen is banana-shaped, with a high middle and low ends. This design makes the movement trajectory of materials on the screen surface more complex, increasing the contact opportunities between materials and the screen surface, which is beneficial for the screening of fine coal. When dealing with fine coal, the Banana Screen can better control the flow rate and thickness of materials, making the screening process more stable and the screening efficiency relatively higher. The following will explore the screening effects of Flip Flow Screen and Banana Screen on fine coal.
Working Principles of Flip Flow Screen and Banana Screen
Flip Flow Screen
The Flip Flow Screen achieves the vibration of the screen body through resonance, and at the same time, it uses the elliptical vibration to drive the other floating beds to expand and contract, so that the vibration amplitude of the floating beds is much larger than that of traditional vibrating screening equipment. Meanwhile, different material groups in the raw coal being screened have their own movement patterns. The separation and screening of different material layers are realized by utilizing the exciting force generated by the movement of the exciter.
Banana Screen
The Banana Screen movement adopts a box-type exciter and transmits the vibration force through couplings and transmission shafts. Under normal working conditions, the exciter drives the screen box to move, allowing the materials on the multi-layer screen to oscillate and advance from the feed inlet to the discharge outlet of the screen body. Different particle sizes and properties of materials are sorted and arranged in sequence. Different inclined screens with an inclination of 4° each are installed on the screen frame, and there are a total of 7 screens, which are installed in decreasing order. Under the same oscillation frequency, the materials on different screens will have different movement speeds and throwing intensities, and they will decrease successively from the feed inlet to the discharge outlet, thus keeping the thickness of the materials from the feed inlet to the discharge outlet basically unchanged and achieving equal-thickness screening of raw coal.
Screening Effect of Flip Flow Screen and Banana Screen
In two sets of screening systems A and B, the raw coal feed, the undersize product after screening, and the oversize product on the upper part of the screening screen were screened according to the specified particle size requirements. The screening effects of the two different screening screens were compared, and the data after screening were sorted and analyzed. The screening effect of the Flip Flow Screen was compared with that of the Banana Screen.
As the input of raw coal increased, the screening rates of both screening screens showed a decreasing trend, but the screening rate of the Banana Screen decreased more significantly. At the same time, when the screening screens were under low load, the screening rates of both screening equipment could reach over 60%, indicating that both screening devices had good application effects at low processing capacities.
As the input of raw coal increased, when the Flip Flow Screen reached 60% of its rated processing capacity, its screening efficiency could still reach over 60%. When the input of raw coal continued to increase, its screening efficiency gradually decreased. When the input of raw coal for the Banana Screen reached 35% of its rated processing capacity, the screening efficiency could still approach 60%. When the input of raw coal continued to increase, the screening rate of the Banana Screen decreased sharply. If a screening rate of 60% is taken as the boundary, the processing capacity of the Banana Screen is lower than that of the Flip Flow Screen, but the processing capacity of the Flip Flow Screen is only 65% of its rated processing capacity. As the input of raw coal increased, the difference in screening rates between the two screening devices became more and more obvious. Although the rated processing capacity of the Banana Screen is higher than that of the Flip Flow Screen, under the premise of ensuring the screening rate, the processing capacity of the Flip Flow Screen is higher than that of the Banana Screen.
Therefore, it can be concluded that under the same working conditions, the screening rate of the Flip Flow Screen is higher than that of the Banana Screen, and its overall performance is also superior to that of the Banana Screen.
Conclusion
By comparing the screening effects of Flip Flow Screen and Banana Screen under the same conditions, it can be seen that under the same conditions, the screening rate of Flip Flow Screen is significantly higher than that of Banana Screen, and its processing capacity is also more prominent. Therefore, in the actual production process, Flip Flow Screen should be given priority for the screening of raw coal to improve the economic benefits of the coal preparation plant and the washing effect of raw coal. At the same time, from the application effect of Flip Flow Screen in the coal preparation plant, it can be seen that there is still a large room for improvement in the washing effect of fine coal by Flip Flow Screen, and continuous optimization research is needed to better meet the needs of fine coal washing in the coal preparation plant.
