Claims
- 1. A multiple hearth furnace comprising:an upright cylindrical furnace housing; a plurality of vertically spaced hearth floors dividing said upright cylindrical furnace housing into a plurality of vertically aligned hearth chambers; a vertical rotary shaft extending centrally through said hearth chambers; at least one rabble arm associated with each of said hearth floors, said rabble arm being fixed to said vertical rotary shaft and being arranged and designed so as to urge, during its rotation, processed material over the associated hearth floor towards a drop hole therein, said processed material falling through said drop hole onto a lower hearth floor; at least one cleaning lance inlet port sealingly connected to said cylindrical furnace housing and radially leading into one of said hearth chambers; and a cleaning lance assembly including: an elongated mount that is arranged outside said furnace housing; and at least one cleaning lance slidably mounted on said elongated mount, said at least one cleaning lance being connected to a cleaning fluid distribution system and comprising at least one cleaning nozzle; wherein: said at least one cleaning lance can be sealingly introduced through said at least one lance inlet port along a radial trajectory into said hearth chamber by moving it along said elongated mount; and said at least one cleaning nozzle is arranged on said cleaning lance, so as to be capable of directing a jet of cleaning fluid onto a rabble arm that is positioned in a cleaning position in the vicinity of said radial trajectory when said cleaning lance is slidably moved along said elongate mount.
- 2. The multiple hearth furnace as claimed in claim 1, wherein said cleaning lance assembly includes:a first cleaning lance slidably mounted on said mount so that it can be introduced through a first lance inlet port in said cylindrical furnace housing along a first radial trajectory into said hearth chamber; a second cleaning lance slidably mounted on said mount so that it can be introduced through a second lance inlet port in said cylindrical furnace housing along a second radial trajectory into the same hearth chamber; said first cleaning lance and said second cleaning lance being connected to a cleaning fluid distribution system and each comprising at least one cleaning nozzle; wherein said first radial trajectory is determined so that said at least one cleaning nozzle of said first cleaning lance is capable of directing its jet of cleaning fluid onto the top of a rabble arm that is positioned in said cleaning position, and said second radial trajectory is determined so that said at least one cleaning nozzle of said second cleaning lance is capable of simultaneously directing its jet of cleaning fluid laterally onto rabble teeth of the same rabble arm in the same cleaning position, when said first cleaning lance and said second cleaning lance are moved along said mount.
- 3. The multiple hearth furnace as claimed in claim 2, wherein said first cleaning lance and said second cleaning lance are mounted on a common lance support carriage that is slidably supported on said mount and driven by an endless chain mounted in said mount.
- 4. The multiple hearth furnace as claimed in claim 1, wherein said cleaning lance comprises at its front end a lateral array of cleaning nozzles.
- 5. The multiple hearth furnace as claimed in claim 4, wherein said cleaning lance comprises at its front end at least one radial cleaning nozzle that is capable of directing a jet of cleaning fluid radially onto said vertical rotary shaft.
- 6. The multiple hearth furnace as claimed in claim 1, wherein said cleaning lance comprises an internal cooling circuit.
- 7. The multiple hearth furnace as claimed in claim 1, wherein said cleaning lance assembly is permanently supported in front of the same lance inlet port.
- 8. The multiple hearth furnace as claimed in claim 1, further comprising a vertical lifting device supporting said cleaning lance assembly, so that the latter can be lifted to different hearth chamber levels, wherein said at least one cleaning lance can be introduced through a lance inlet port into the respective hearth chamber at each of said hearth chamber levels.
- 9. The multiple hearth furnace as claimed in claim 8, wherein said mount has a front end and a rear end and comprises a support roller for said at least one cleaning lance on its front end.
- 10. The multiple hearth furnace as claimed in claim 8, wherein said cleaning lance assembly is pivotably supported by said vertical lifting device, so that it can be rotated about a substantially vertical axis between an operating position, in which said at least one cleaning lance is substantially parallel to a central axis of a lance inlet port, and a lifting position, in which said at least one cleaning lance is substantially perpendicular to said central axis of said lance inlet port.
- 11. The multiple hearth furnace as claimed in claim 10, wherein said vertical lifting device includes:a vertical rail assembly that is supported so as to be capable of rotating about its vertical axis; a lifting carriage slidably supported in said vertical rail assembly, said cleaning lance assembly being supported by said lifting carriage; first drive means for moving said lifting carriage along said vertical rail assembly; and second drive means for rotating said vertical rail assembly by an angle of 90° about its vertical axis.
- 12. The multiple hearth furnace as claimed in claim 1, wherein said lance inlet port includes:a rigid inlet pipe connected to said cylindrical furnace housing; a ring-shaped lance sealing body connected to said rigid inlet pipe by means of a gastight flexible joint.
- 13. The multiple hearth furnace as claimed in claim 12, wherein said lance inlet port includes a pivotable sealing flap.
- 14. The multiple hearth furnace as claimed in claim 1, wherein said lance inlet port includes a pivotable sealing flap.
- 15. The multiple hearth furnace as claimed in claim 1, wherein said cleaning fluid is a gas-water mixture or mist.
Priority Claims (1)
Number |
Date |
Country |
Kind |
90793 |
Jun 2001 |
LU |
|
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is entitled to the benefit of and incorporates by reference in their entireties essential subject matter disclosed in International Application No. PCT/EP02/06683 filed on Jun. 18, 2002 and Luxembourg Patent Application No. 90 793 filed on Jun. 26, 2001.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/EP02/06683 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO03/00292 |
1/9/2003 |
WO |
A |
US Referenced Citations (11)
Foreign Referenced Citations (1)
Number |
Date |
Country |
8624717 |
Oct 1986 |
DE |