Cement and Energy

NEW V- SEPARATOR T he V-Scpararor (VS) was developed by KHD Humboldt Wedag as a response to the extreme conditions of particle size and abrasiveness common ly experienced with products from modern and energy– saving high-pressure commi nution machines. It is distinguished by a robust design wi th the absence of any rotating or moving parts, good efficiency of separation with high solids-to-air-loading and the abi lity to disagglomcratc. Design and Working VS is a combination of a erossflow and upstream classifier (Figure I). The feed material cascades down a Figure I: Y-Separator steeply angled array of downwards pointing bafnes. Opposite the cascade is an upwards pointing series of classifying channels. Fine and medi um-sized particles arc dragged out of the cascading !low of solids by the cross-flow or air and transported into the classifying channels. From there, the fines are lifted to the exit, whilst the medium sized particles follow the force of gravity to join the rapid downllow of all the coarse particles towards the bottom outlet. Good efficiency of separation is maintained with solid-to-air ratio ratings or up to 4 kg./m 1 . Experience Hitherto Since the first YS unit ~as commissioned, plant Counesv : International Cemen t Review, December 1996 performance regarding process, cement quality and wear was closely monitored. The mai n findings are : • The dynamic separator, now connected to the tube mill, made not only the tube mi ll work more efficiently, but is now also operating with very lilLie signs of wear. • Inside the VS itself, the initial concrete lining of the front end elements of both, the cascade steps and the classifying channels, broke away under impact of the clinker particles. However, the mi ld steel backing plate, once exposed, lasted in these piaces much longer than the actual concrete iining. Replaci ng these front elements with manganese steel castings brought the expected increase in lifetime (20,000 h until today). The design allows quick and easy exchange of these elements. The overall experience with the VS at the plant in question can be summarised as : * * * Good efficiency of separation Effective deglomeration of pressed clinker cake Much reduced maintenance cost Significantl y lower energy consumption Excellent cement quality The future The VS has also shown good potential in classifying a variety of materials other than cement or cement raw material, for instance : • Dcdusting of industrial minerals and ores. • Splitting of fines from coal with moisture levels of up to 8%. The decision to dry or not to dry within the VS depends on the type of coal , its ini tial moi sture content and requirements regarding the further use of the product. • A most promising concept is single-stage grinding with roller press whereby a new type of YS with integrated high efficiency cage-wheel allows most energy-saving size reduction of a wide range of materials, especially industrial minerals. 8 - -