FINE GRINDING ROLLER MILL

• US 20090121060A1
• Filed: 11/13/2008
• Published: 05/14/2009
• Est. Priority Date: 11/14/2007
• Status: Active Grant

• Current Assignee: Schenck Process LLC (Schenck Process Holding GmbH)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Chen, Michael M.
• Granted Patent: US 7,963,471 B2
• Time in Patent Office: Days
• US Class Current: 241/110
• CPC Class Codes: B02C 15/003 Shape or construction of discs or rings
• CPC Class Codes: B02C 15/004 Shape or construction of rollers or balls
• CPC Class Codes: B02C 15/02 Centrifugal pendulum-type mills
• CPC Class Codes: B02C 2015/002 combined with a classifier

Abstract

A roller mill 10 for pulverizing fine material has a grinding mechanism that includes a plurality of grinding rolls 64 and a grinding ring 66 that coact to pulverize material within a mill housing. The grinding ring has an inner grinding surface wherein the inner surface includes an upper vertical portion and inwardly sloped lower portion. The lower portion of the ring provides a means for retaining more fine particles on the ring during pulverizing, as well as an increase in grinding surface. The grinding rolls have a generally cylindrical shape with an outer grinding surface that includes an upper vertical portion and a lower portion of the outer grinding surface. The outer grinding surface of the roll is complementary to the inner grinding surface of the grinding ring.

Claims

1. A grinding mechanism for a roller mill for pulverizing material;

said grinding mechanism comprising;

a grinding ring having an inner grinding surface wherein the inner grinding surface includes an inwardly sloped lower portion; and

a grinding roll that coacts with the grinding ring to pulverize the material, the grinding roll having a generally cylindrical shape with an outer grinding surface wherein a lower portion of the outer grinding surface is complementary to the inner grinding surface of the grinding ring.

2. The grinding mechanism of claim 1, wherein the inner grinding surface of the grinding ring has a substantially vertical upper portion.

3. The grinding mechanism of claim 1, wherein the lower portion of the inner grinding surface of the grinding ring is curved.

4. The grinding mechanism of claim 1, wherein the lower portion of the inner grinding surface of the grinding ring is concave.

5. The grinding mechanism of claim 1, wherein the lower portion of the inner grinding surface of the grinding ring is generally frustoconical.

6. The grinding mechanism of claim 2, wherein the outer grinding surface of the roll has a substantially vertical upper portion.

7. The grinding mechanism of claim 1, wherein the lower portion and an upper portion of the inner grinding surface of the grinding ring are sloped inwardly downward.

8. The grinding mechanism of claim 1, wherein the lower portion of the ring extends inwardly to shield a portion of the material disposed on the inner grinding surface of the grinding ring.

9. The grinding mechanism of claim 1, wherein the lower portion of the ring extends inwardly approximately one eighth to one half of the height of the roll.

10. The grinding mechanism of claim 1, wherein a substantial portion of the inner grinding surface of the grinding ring slopes inwardly downward.

11. The grinding mechanism of claim 4, wherein the inner grinding surface of the grinding ring includes a concave upper portion.

12. The grinding mechanism of claim 1, further including:

a mill housing that defines a grinding chamber;

a classifier including a rotor having a plurality of blades disposed within a classifier housing defining a classifying chamber, where the rotor rotates to separate fine sized particles from oversized particles, whereby the finer sized particles pass through the blades and exit the classifier and the oversized particles are propelled outward against the classifier housing, the grinding chamber being in fluid communication with the classifying chamber; and

a baffle disposed along the inner periphery of the mill housing spaced at a distance from the mill housing to provide an inner passage and an outer annular passage, the inner passage for directing particle laden air upward through the grinding chamber to the classifier, the outer annular passage receiving and directing the oversized particles downward to the grinding mechanism of the mill such that the baffle minimizes influence of the upward particle-laden airflow through the inner passage of the grinding chamber with the downward flow of the oversized particles, the baffle having an opening at the bottom of the outer annular passage for directing the oversized particles to the grinding mechanism.

13. The grinding mechanism of claim 1, further including a journal having a threaded end portion, wherein the threaded end of the journal extends through a central hole in the roll whereby a threaded fastener engages the threaded end of the journal for securing the roll to the journal.

14. The grinding mechanism of claim 1, wherein the grinding roll includes a tread extending from the outer grinding surface of the grinding roll.

15. The grinding mechanism of claim 1, wherein the grinding ring includes a tread extending from the inner grinding surface of the grinding.

16. A grinding mechanism for a roller mill for pulverizing material;

said grinding mechanism comprising;

a grinding ring having an inner grinding surface; and

a grinding roll that coacts with the grinding ring to pulverize the material, the grinding roll having a generally cylindrical shape with an outer grinding surface wherein at least one of the inner surface of the ring and the outer surface of the roll includes a tread.

17. The grinding mechanism of claim 16, wherein the tread extends from at least one of the inner surface of the ring and the outer surface of the roll.

18. The grinding mechanism of claim 17, wherein the tread includes a plurality of protrusions circumferentially-spaced around at least one of the inner surface of the ring and the outer surface of the roll

19. The grinding mechanism of claim 17, wherein the tread includes a plurality of ribs circumferentially-spaced around at least one of the inner surface of the ring and the outer surface of the roll

20. The grinding mechanism of claim 18, wherein the protrusions are spaced such that only one protrusion substantially engages the inner grinding surface of the ring.