A Rolling Success – part three

By installing the flow-rectification plates and blade ring, the gas flowing into the separator became smoother in comparison to the conventional designand for the gas flowing out of the separator to the outlet duct, uneven velocity was solved by decentring the outlet duct to allow even discharge of gas in circumferential direction.

The company used classified particle size to evaluate the effectiveness on the classification of the separator after uneven velocity correction.

d0: particle size classified in ideal condition.
d: calculated classified particle distribution.

The company calculated how much d varies from d0 at each section of the separator. Any d/d0 less than 1.0 means that the classified particle size is small. At this classification, even the particles that reach the required fineness get rejected as to the gas velocity passing through the separator is too slow.

In conventional design, the left side (from the outlet duct’s perspective) had large classified particle size while the classified particle size of the opposing side (right side) was small. In contrast, the new design, comprising the blade ring design and decentred duct, has greatly resolved the uneven velocity issue, and classification close to the ideal classification has become possible. From this effect, not only has operation with lower vibration than the conventional design become possible, but power consumption of the mill, separator, and fan has also reduced by 5%. The company is planning on standardising these new designs for the future cement mills.

Conclusion

UBE has a global delivery record of over 540 VRMs and is part of UBE Industries Group, which owns three cement plants within Japan, where 14 UBE VRMs are in operation. Among the 14 VRMs delivered to the company’s cement plants, the oldest model was delivered in 1973 and is still operating smoothly with no major issues at the time of writing.

The company has used its long-term operating experience and feedback received directly from its cement plants to improve the performance of VRMs. The company is dedicated to continuing the development and supply of industry-leading VRMs and to supporting its customers throughout the world by providing cement quality and grindability testing and analysis as one part of its total support philosophy.

This is part three of a three-part article written for World Cement’s February issue and abridged for the website. Subscribers can read the full issue by signing in, and can also catch up on-the-go via our new app for Apple and Android. Non-subscribers can access a preview of the December 2015 issue here.

Read the article online at: https://www.worldcement.com/special-reports/08022016/rolling-success-part-three/