Rotary degasser and rotor therefor

Patent metadata

Field	Value
Publication number	US-9506129-B2
Application number	US-201514918471-A
Country	US
Kind code	B2
Filing date	Oct 20, 2015
Priority date	Aug 7, 2009
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

A device for dispersing gas into molten metal includes an impeller, a drive shaft having a gas-transfer passage therein, and a first end and a second end, and a drive source. The second end of the drive shaft is connected to the impeller and the first end is connected to the drive source. The impeller includes a first portion and a second portion with a plurality of cavities. The first portion covers the second portion to help prevent gas from escaping to the surface without entering the cavities and being mixed with molten metal as the impeller rotates. When gas is transferred through the gas-transfer passage, it exits through the gas-release opening(s) in the bottom of the impeller. At least some of the gas enters the cavities where it is mixed with the molten metal being displaced by the impeller. Also disclosed are impellers that can be used to practice the invention.

First claim

What is claimed is:

1. A device for releasing and mixing gas into molten metal, the device comprising:
(a) a motor;
(b) a drive shaft having a first end connected to the motor and a second end, the drive shaft having a passage through which gas can travel and opening at the second end through which the gas is released; and
(c) an impeller for dispersing gas into the molten metal and being connected to the second end of the drive shaft, the impeller having:
(i) a gas-release opening through which gas from the second end of the drive shaft is released;
(ii) a top portion having a first lower surface;
(iii) a second portion below the first lower surface and connected to the first lower surface, the second portion including a second lower surface, a plurality of cavities and a protrusion between each of the plurality of cavities, wherein each protrusion has an edge for shearing gas as the impeller rotates, and the cavities, protrusions and edges are covered by the first lower surface; and
(iv) a plurality of channels, wherein each of the plurality of channels leads to one of the cavities;
wherein when gas is released from the gas-release opening it rises into the plurality of cavities and the lower surface of the top portion helps to retain the gas in the plurality of cavities to help mix the gas and molten metal, and the edges of the protrusions shear the gas into smaller bubbles to assist in mixing the gas with the molten metal.

2. The device of claim 1 , wherein the drive shaft is comprised of:
(1) a motor shaft having a first end and second end; and
(2) an impeller shaft having a first end and second end, the first end of the drive shaft being connected to the drive source and the second end of the motor shaft being coupled to the first end of the impeller shaft.

3. The device of claim 2 further comprising a coupling for connecting the drive shaft to the impeller shaft, the coupling having a first portion connected to the second end of the drive shaft and a second portion connected to the first end of the impeller shaft.

4. The device of claim 1 , wherein each of the plurality of cavities is the same size and shape.

5. The device of claim 1 , wherein the first lower surface has an outer perimeter, each cavity has a curved side surface, and at least part of each of each curved side surface is inside the outer perimeter of the first lower surface.

6. The device of claim 1 , wherein the impeller has four channels and each channel leads to the center of one respective curved side surface.

7. The device of claim 1 , wherein each of the cavities is beneath the lower surface of the top portion.

8. The device of claim 1 , wherein there are eight cavities.

9. The device of claim 1 , wherein the impeller has a center and gas is released from an opening positioned at the center of the second lower surface.

10. The device of claim 1 , wherein each cavity is defined by a fully curved side surface and a top surface, and the channel extends from the center of the impeller to the center of the curved side surface.

11. The device of claim 1 that is comprised of graphite.

12. An impeller for dispersing gas into the molten metal and being connected to the second end of the drive shaft, the impeller having:
(i) a gas-release opening through which gas is released;
(ii) a top portion having a first lower surface;
(iii) a second portion below the first lower surface and connected to the lower surface, the second portion including a second lower surface, a plurality of cavities and a protrusion between each of the plurality of cavities, wherein each protrusion has an edge for shearing gas as the impeller rotates, and the cavities, protrusions and edges are covered by the first lower surface; and
(iv) a plurality of channels, wherein each of the plurality of channels leads to one of the cavities;

wherein when gas is released from the gas-release opening it rises into the plurality of cavities and the lower surface of the top portion helps to retain the gas in the plurality of cavities to help mix the gas and molten metal, and the edges of the protrusions shear the gas into smaller bubbles to assist in mixing the gas with the molten metal.

13. The impeller of claim 12 , wherein each of the plurality of cavities is the same size and shape.

14. The impeller of claim 12 , wherein the first lower surface has an outer perimeter, each cavity has a curved side surface, and at least part of each of each curved side surface is inside the outer perimeter of the first lower surface.

15. The impeller of claim 12 , wherein the impeller has four channels and each channel leads to the center of one respective curved side surface.

16. The impeller of claim 12 , wherein there are eight cavities.

17. The impeller of claim 12 , wherein the impeller has a center and gas is released from an opening positioned at the center of the second lower surface.

18. The impeller of claim 12 , wherein each cavity is defined by a fully curved side surface and a top surface, and the channel extends from the center of the impeller to the center of the curved side surface.

19. The impeller of claim 12 that is comprised of graphite.

Assignees

• Molten Metal Equipment Innovations Llc

Inventors

• Cooper Paul V

Classifications

• C22B9/05 Primary

  Refining by treating with gases, e.g. gas flushing {also refining by means of a material generating gas in situ} · CPC title

• F01D5/147

  Construction, i.e. structural features, e.g. of weight-saving hollow blades (F01D5/148, F01D5/16 and F01D5/20 take precedence; blade shape F01D5/141; blades with cooling or heating channels or cavities F01D5/18; heating, heat-insulating or cooling means on blades F01D5/18) · CPC title

• C21C1/06

  Constructional features of mixers for pig-iron · CPC title

• F27D27/00

  Stirring devices for molten material (charging or discharging liquid or molten material F27D3/14) · CPC title

• F27D3/16

  Introducing a fluid jet or current into the charge (F27D3/18 takes precedence) · CPC title