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CEMENT PRODUCTION PROCESS

CEMENT PRODUCTION PROCESS. ROLLER MILL. ROLLER MILL. V ertical R oller M ill (VRM) - 3 Sections. Separation  Grinding  Drive . Vertical Roller Mill (VRM) - Details. VRM - Working principle. Grinding force = Roller weight + (pressure) Force. Material bed.

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CEMENT PRODUCTION PROCESS

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  1. CEMENT PRODUCTION PROCESS ROLLER MILL

  2. ROLLER MILL

  3. VerticalRollerMill(VRM)- 3 Sections Separation  Grinding  Drive 

  4. Vertical Roller Mill (VRM) - Details

  5. VRM - Working principle Grinding force = Roller weight + (pressure) Force Material bed Roller rolls freely with table Feed material Table moves with drive Max Particle size in feed: 5-8 % of roller diameter

  6. VRM - Material Flow inside Separator: removes fine material rejects coarse material Gas & Product Material Feed Material Internal gas flow Separator Rejects Internal Circulation Large Material falls through to scraper Material Material & Gas Gas

  7. VRM - Some Common Mill Configurations G.Pfeiffer Loesche FLS Atox Polysius

  8. VRM - Built-in Separator Static type Conventional Rotor type Cage Rotor type Separation control: 1. Vane adjustment 2. Speed control

  9. Separators of 3rd Generation (Vertical roller mill) Reject cone Cage rotor Guide vane system

  10. VRM - Separator Fotos Angle affects product sizing Rotor speed affects product fineness Rotor seal affects separator efficiency

  11. Potential Problems/clogging Cage rotor separator casing partly clogged guide vane system Material deposits due to insufficient airflow or airflow distribution

  12. VRM - External Circulation Used for reducing gas flow pressure lost over the mill (less pneumatic internal circulation)

  13. VRM - Example flow-sheet • Control points • gas flow • pressure difference • return gas flow pressure • outlet temperature • external recirculation

  14. VRM - Control & Maintenance Control • Gearbox - Vibration monitor - Temperature monitor • Gas flow - Temperatures & pressures • Hydraulics - Pressures Maintenance • Wear - Rollers & Table - Separator (sealing!) & Housing • Lubrication & Hydraulics (filters and seals)

  15. VRM - Control

  16. Vertical roller mill internals suffering from wear Outlet duct Inlet chute Separator Separator cone Mill housing Armour & nozzle rings Rollers and table liners Scrapers

  17. Roller and grinding track liners Grinding track liners: • Monobloc • Segments Roller liners: • Monobloc • Segments

  18. Wear resistance material alternatives • Nihard 4 • High Chromium alloys % C % Cr % Ni Weldable < 3.5 < 10 < 6.5 yes % C % Cr % Other Weldable Example < 3.6 < 17 Mo + Ni yes Chromodur, FMU18, VegalineV16s < 20 Mn < 2.6 No FMU 52 < 3.5 < 28 < 1.2 No FMU 46

  19. Wear resistance material alternatives • Metallic inserts roller liner Soft material base Hard metallic insert

  20. Wear resistance material alternatives • Ceramic inserts roller and grinding track liners Metallic base (High Cr) Ceramic insert

  21. 40 [mm] = ~ 2’000 [h] 2’500 [h] = 50 [mm] Minimum allowed thickness Wear rate monitoring

  22. Wear resistance material alternatives • Surface reconditioning on grinding track and roller liners % C % Cr %Others Weldable Example < 29 Ni, Mo yes < 5 Vautid 100, HC-O < 5.5 ~ 22 6 – 7 Ni yes CN-O, CNV-O

  23. VRM - Accessories Rotary valve Pendulum valve Reduces false air entering with feed material. Good for dry, small size material. Reduces false air entering. Better for lumpy or humid feed material. Weigh belt Metal extraction Metal objects damage the roller & table. The magnet removes them Weighs the passing material ensuring a continuous grinding bed in the mill

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