System for releasing gas into molten metal

Abstract

A device for releasing gas into molten metal includes a base having a discharge. The discharge has a first section including a first cross-sectional area and a second section including a second cross-sectional area, wherein the first section is upstream of the second section and the first cross-sectional area is smaller than the second cross-sectional area. A gas-release opening is positioned so that it can release gas into one or more of the first section or the second section. As the molten metal moves from the first cross-sectional area to the second cross-sectional area gas is released into the molten metal and the molten metal flow helps to draw the gas into the flow, thereby lowering the pressure required to release gas into the molten metal. Metal-transfer conduits other than a discharge incorporated in a pump base are also disclosed, as are pumps including either a discharge or other metal-transfer conduit according to the invention.

1 . A base for a molten metal pump, the base comprising: 
 a pump chamber;    a discharge in communication with the pump chamber, the discharge including a first section having a first cross-sectional area and a second section having a second cross-sectional area, the second section being downstream of the first section and the second cross-sectional area being larger than the first cross-sectional area; and    a gas-release opening in communication with one or more of the group consisting of the first section and the second section.    
   
   
       2 . The base of  claim 1  wherein the gas-release opening is positioned in the second section.  
   
   
       3 . The base of  claim 2  wherein the gas-release opening is positioned along a side wall of the second section.  
   
   
       4 . The base of  claim 2  wherein the gas-release opening is positioned near a top wall of the second section.  
   
   
       5 . The base of  claim 1  wherein the gas-release opening is positioned in the first section.  
   
   
       6 . The base of  claim 5  wherein the gas-release opening is positioned in a top wall of the first section.  
   
   
       7 . The base of  claim 2  wherein the gas-release opening is positioned within 3″ of the first section.  
   
   
       8 . The base of  claim 1  wherein the discharge is fully enclosed.  
   
   
       9 . The base of  claim 1  wherein the second cross-sectional area is between 110% and 350% larger than the first cross-sectional area.  
   
   
       10 . The base of  claim 1  wherein the discharge further includes a third section having a third cross-sectional area, the third section being downstream of the second section and the third cross-sectional area being larger than the first cross-sectional area but smaller than the second cross-sectional area.  
   
   
       11 . The base of  claim 1  that is comprised of graphite.  
   
   
       12 . A molten metal pump including: 
 a base for a molten metal pump, the base comprising:    a pump chamber;    a discharge in communication with the pump chamber, the discharge including a first section having a first cross-sectional area and a second section having a second cross-sectional area, the second section being downstream of the first section and the second cross-sectional area being larger than the first cross-sectional area; and    a gas-release opening in communication with one or more of the group consisting of the first section and the second section.    
   
   
       13 . The molten metal pump of  claim 12  that further comprises a gas-transfer conduit, the gas-transfer conduit having an end including the gas-release opening and an opposite end connected to a gas source, wherein gas from the gas source can pass through the gas-transfer conduit, through the gas-release opening and into the discharge.  
   
   
       14 . The molten metal pump of  claim 12  that further includes a metal-transfer conduit connected to the discharge.  
   
   
       15 . The molten metal pump of  claim 12  wherein the gas-release opening is positioned in the second section.  
   
   
       16 . The molten metal pump of  claim 15  wherein the gas-release opening is positioned less than 12″ from the first section.  
   
   
       17 . The molten metal pump of  claim 15  wherein the gas-release opening is positioned within 3″ of the first section.  
   
   
       18 . The molten metal pump of  claim 12  wherein the discharge is fully enclosed.  
   
   
       19 . The molten metal pump of  claim 12  that further includes a device positioned in a pump chamber in the pump base, the device having a displacement structure and an inlet structure defining one or more inlets wherein the displacement structure and the inlet structure rotate as the device rotates.  
   
   
       20 . The pump of  claim 15  wherein the gas-release opening is positioned near a top wall of the second section.  
   
   
       21 . The pump of  claim 12  wherein the gas-release opening is positioned in the first section.  
   
   
       22 . The pump of  claim 21  wherein the gas-release opening is positioned near a top wall of the first section.  
   
   
       23 . The pump of  claim 12  wherein the discharge further includes a third section having a third cross-sectional area, the third section being downstream of the second section and the third cross-sectional area being larger than the first cross-sectional area but smaller than the second cross-sectional area.  
   
   
       24 . A metal-transfer conduit for connecting to a molten metal pump base, the metal-transfer conduit having a first section with a first cross-sectional area and a second section with a second cross-sectional area, the second cross-sectional area being greater than the first cross-sectional area and a gas-release opening in communication with one or more of the group consisting of the first section and the second section.  
   
   
       25 . The metal transfer conduit of  claim 24  wherein the gas-release opening is positioned in the second section.  
   
   
       26 . The metal-transfer conduit of  claim 24  wherein the gas-release opening is positioned within 3″ of the first section.  
   
   
       27 . The metal-transfer conduit of  claim 24  wherein the second section has a side wall and the gas-release opening is positioned near the side wall.  
   
   
       28 . The metal-transfer conduit of  claim 23  wherein the second cross-sectional area is between 110% and 350% of the area of the first cross-sectional area.  
   
   
       29 . The metal-transfer conduit of  claim 24  that is made of graphite.  
   
   
       30 . The metal-transfer conduit of  claim 25  wherein the gas-release opening is positioned within 12″ of the first section.  
   
   
       31 . The metal-transfer conduit of  claim 25  wherein the gas-release opening is positioned near a top wall of the second section.  
   
   
       32 . The metal-transfer conduit of  claim 24  wherein the gas-release opening is formed in the first section.  
   
   
       33 . The metal-transfer conduit of  claim 32  wherein the gas-release opening is formed in a top wall of the first section.  
   
   
       34 . The metal-transfer of  claim 24  wherein the second cross-sectional area is between 110% and 350% larger than the first cross-sectional area.  
   
   
       35 . The metal-transfer conduit of  claim 24  wherein the discharge further includes a third section having a third cross-sectional area, the third section being downstream of the second section and the third cross-sectional area being larger than the first cross-sectional area but smaller than the second cross-sectional area.  
   
   
       36 . The base of  claim 1  wherein there is as-release opening in communication with the first section and a gas-release opening in communication with the second section.  
   
   
       37 . The pump of  claim 12  wherein there is a gas-release opening in communication with the first section and a gas-release opening in communication with the second section.  
   
   
       38 . The metal-transfer conduit of  claim 24  wherein there is a gas-release opening in communication with the first section and a gas-release opening in communication with the second section.