Cement and Energy

Studies have demonst rated that vi rtually no flow losses occur in the area outside the dip tube radius. The main reasons for the flow losses are the vortex or the cyclonic flow in the axial zone of the centrifugal separator. Th is makes clear that the cycloni c core in the separation chamber and the ex hau st pipe, lead to very hi gh acceleration and turbulence in the proximity of the ax is. which can be regmded as the main cause of the sizeable flow losses. l n particular, the dip tube design has a major effect on the flow configuration. Demands on the intake device In view of the practical demands fo r smooth operation th roughout the plant's service life, dip design shou ld secure minimum pressure losses . The so luti on mu st therefore be simple, as low manufacturing costs firs t ensure economic appli cation on a large technical scale. One precondition is that the classifying capacity of the separator may not be adversely affected, as then its main function. namely, good separat ion, wo uld not be fulfill ed. Hence, the theoretica l target for a practica l solution with regard to centrifugal cyclone separators can he formu lated as being the use of an exhaust pipe dev ice, which is virtually as simple as the exhaust itself. ln more precise terms. this means: • Generally no rree flow smaller than around I00 mm. • No increased operational procedure demands. • The tendency to improved separation under otherwi se unchanged conditions. Known dip tube forms Reverse exhausl air spiral : Under laboratory cond itions, the reverse air spi ral can provide pressure loss reductions of 25%, particularly when it has a very f lat shape. However, this is frequently impossib le for smooth operati on, as deposits quickly have a negative effect on results. Therefore, an exhaust air spiral is more important under c ramped structural condition s. where a more favourable pipe intake is possible. In current terms. the contribution to energy savings is moderate. Conical dip tubes : Due to their simplicity, conical di p pipes are quite practical in high- performance cyclones. Their co ntribu tion to sav ing energy is moderate, but acceptable in relation to the costs. The actual effect in combination with the exhaust air spiral and the exhaust p1p1ng system can frequ ently not be assessed without model testi ng. Prac tical utilisat ion is therefore problematic, as energy savings are virtuall y impossible to prove. Annual passage d([{ttser soltt!ion s 11·ith numerous guide vanes : These solutions provide good results, but due to the high manufacturing costs and their tendency to defects caused by the relatively small tlow channels, are seldom used and have little meaning on a major technical scale. In addit ion, to attain correspond ingly good res ult s, without precise model tests the design of such annu lar passage guide vane apparatus is impossible. Aga in, a limited effect is onl y apparent whe n the process parameters arc altered. The Hurriclon vortex finder vanes This system is a simple tube, which takes in the gas tlow just within the di p tube radius, where the flow losses are small , and creates a favourable flow path into the exhaust its el f. During compara ti ve testing, th e new, low, resistance value for the exhaust flow was established and then implememed in accordance with the model laws in the large-scale sizes required under practica l cond itions . Ope rational measuremen ts confirm the fu nd amental in formation gathered during comparati ve testing and are simultaneously the springboard for the new technology demonstrated under practical conditions (Figu re I) 10