Cement Americas

WIN 2016

Cement Americas provides comprehensive coverage of the North and South American cement markets from raw material extraction to delivery and tranportation to end user.

Issue link: https://cement.epubxp.com/i/636168

Contents of this Issue

Navigation

Page 8 of 39

www.cementamericas.com • Winter 2016 • CEMENT AMERICAS 7 FEATURE WEAR PROTECTION IN A ROTARY VALVE The DuroProtect wear protection concept for rotary valves was developed based on the results of the Co- perion wear test facility and other research projects. The Duroprotect wear protection packages incorporate various suitable materials for wear protection and re- fect the impact of product hardness (Mohs hardness scale from 1 to 10) and conveying pressure on the wear behavior of the equipment. WEAR PROTECTION MATERIALS As shown in Figure 5 the wear tests have shown that the following three wear protection materials are the most suitable protection layers to ensure a long life- time: • Chrome. Chrome layers (DuroChrom) are applied in different thicknesses on the housing bore, end plates and the rotor tips for lower conveying pressures and product hardness. • Tungsten Carbide. Tung- sten Carbide (DuroCarb) is used for the tips of the rotor. Depending on the method of application of the Tungsten Carbide, changes in the matrix structure can result in further considerable improvements in the wear behavior. • Ceramic. Ceramic (DuroCera) is used inside of the housing bore and on end plates for wear protection at high conveying pressures and hard materials like cement or alumina. ROTOR DESIGN Both the wear protection material and the rotor design have an impact on the lifetime and wear resistance of the rotary valve. As shown in Figure 8, an open rotor is used for a drop-through rotary valve with lower con- veying pressures. With increasing conveying capacity a closed rotor, shown in Figure 9, is used to help prevent the material from contacting the end plates and sealing system. To avoid the material getting stuck between the rotor and the end plates, a seal purge system is required. CASE STUDIES OF ROTARY VALVES IN THE MINERALS INDUSTRY Alumina ship unloading with a vacuum suction system A double station with two Coperion ZPC 800 rotary valves with DuroProtect 5 fnish (ceramic in the hous- ing; tungsten carbide on the rotor) was installed in a vacuum ship unloader at an aluminum smelter. The ro- tary valves run at a capacity of 220 tph at a vacuum of 5.8 psi and discharge alumina (Mohs hardness 9) Figure 5: Coperion DuroProtect packages. Figure 6: Tungsten carbide welding. Figure 7: Ceramic housing. Figure 8: Open end rotor. Figure 9: Closed end rotor. Figure 10: Vacuum ship unloader and rotary valve station.

Articles in this issue

Links on this page

Archives of this issue

view archives of Cement Americas - WIN 2016