U.S. patent application number 11/413982 was filed with the patent office on 2007-11-01 for gas-transfer foot.
Invention is credited to Paul V. Cooper.
Application Number | 20070253807 11/413982 |
Document ID | / |
Family ID | 38648482 |
Filed Date | 2007-11-01 |
United States Patent
Application |
20070253807 |
Kind Code |
A1 |
Cooper; Paul V. |
November 1, 2007 |
Gas-transfer foot
Abstract
The present invention includes a molten metal pump and
associated components that enable gas to be released into a stream
of molten metal. The gas may be released into the molten metal
stream (preferably into the bottom of the stream) flowing through a
passage. Such a stream may be within the pump discharge and/or
within a metal-transfer conduit extending from the pump discharge.
The gas is released by using a gas-transfer foot that is positioned
next to and is preferably attachable to the pump base or to the
metal-transfer conduit. Preferably, the conduit (and/or discharge)
in which the gas is released comprises two sections: a first
section having a first cross-sectional area and a second section
downstream of the first section and having a second cross-sectional
area, wherein the second cross sectional area is larger than the
first cross-sectional area. Preferably, the gas is released into or
near the second section so that the gas is released into an area of
relatively lower pressure.
Inventors: |
Cooper; Paul V.;
(Chesterland, OH) |
Correspondence
Address: |
SQUIRE SANDERS & DEMPSEY LLP
TWO RENAISSANCE SQUARE, 40 NORTH CENTRAL AVENUE
SUITE 2700
PHOENIX
AZ
85004-4498
US
|
Family ID: |
38648482 |
Appl. No.: |
11/413982 |
Filed: |
April 28, 2006 |
Current U.S.
Class: |
415/90 |
Current CPC
Class: |
F17D 1/04 20130101; F04D
7/065 20130101; F04D 7/00 20130101; Y10T 137/85978 20150401; F04D
29/708 20130101; F04D 31/00 20130101 |
Class at
Publication: |
415/090 |
International
Class: |
F01D 1/36 20060101
F01D001/36 |
Claims
1. A molten metal pump including: (a) a motor; (b) a rotor; (c) a
shaft connecting the motor to the rotor; (d) a base comprising: a
pump chamber; a discharge in communication with the pump chamber,
the discharge having a bottom surface and 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 greater
than the first cross-sectional area; and an opening on the bottom
surface in communication with one or more of the group consisting
of the first section and the section; and (e) a gas-transfer foot,
the gas-transfer foot comprising: a gas-inlet port through which
gas enters the foot; and a gas-outlet port in communication with
the opening so that gas can be transferred from the gas-outlet port
through the opening and into the discharge.
2. The pump of claim 1 wherein the gas-transfer foot is connected
to the base.
3. The pump of claim 1 wherein a notch is constructed in the base,
the notch configured to receive at least part of the gas-transfer
foot such when the gas-transfer foot is received in the notch the
gas-outlet port is in communication with the opening.
4. The pump of claim 1 that further includes a metal-transfer
conduit extending from the discharge.
5. The pump of claim 1 wherein the opening is in the first
section.
6. The pump of claim 1 wherein opening is in the second
section.
7. The pump of claim 1 wherein opening is in both the first section
and the second section.
8. The pump of claim 1 that further includes a gas-transfer conduit
having a first end connectable to a gas source and a second end
connectable to the gas-inlet port of the gas-release foot.
9. The pump of claim 1 wherein the pump base and the gas-transfer
foot are comprised of graphite.
10. The pump of claim 1 wherein the notch has a first end at a side
of the base and a second end opposite the first end, the first end
having a width greater than the width of the second end.
11. The pump of claim 10 wherein the gas release opening is formed
at the second end.
12. The pump of claim 1 that further includes a metal-transfer
conduit in communication with the discharge such that at least some
of the molten metal moving through the discharge enters and passes
through the metal-transfer conduit.
13. The pump of claim 12 that further includes a structure for
releasing gas into the discharge.
14. The pump of claim 1 wherein the discharge has sections in
addition to the first section and second section.
15. A molten metal pump including: (a) a motor; (b) a rotor; (c) a
shaft connecting the motor to the rotor; (d) a base comprising: a
pump chamber; and a discharge in communication with the pump
chamber; (e) a metal-transfer conduit extending from the discharge,
the metal-transfer conduit in communication with the discharge such
that at least some of the molten metal moving through the discharge
also moves through the metal-transfer conduit; the metal-transfer
conduit having an internal channel 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 greater
than the first cross-sectional area; and a gas-release opening on
the bottom surface of the channel in communication with one or more
of the group consisting of the first section and the second
section; and (f) a gas-transfer foot comprising: a gas inlet port
through which gas passes into the gas-transfer foot; and a gas
outlet port in communication with the gas-release opening so that
gas can be transferred from the gas outlet port through the
gas-release opening into the conduit path.
16. The pump of claim 15, wherein a notch is formed in the
metal-transfer conduit such that when the gas-transfer foot is
inserted into the notch it is in communication with the gas-release
opening.
17. The pump of claim 15 wherein the gas-release opening is in
communication with the first section.
18. The pump of claim 15 wherein the gas-release opening is in
communication with the second section.
19. The pump of claim 15 wherein the internal channel has sections
in addition to the first section and second section.
20. A gas-transfer assembly for a molten metal pump, the
gas-transfer assembly comprising: (a) a gas-transfer conduit having
a gas-release end and an opposite end connectable to a gas source;
and (b) a gas-transfer foot, the gas-transfer foot comprising: a
gas-inlet port in communication with the gas-release end of the
gas-transfer tube; and a gas-outlet port downstream from the gas
inlet port, wherein the gas-transfer foot is attachable to a
component of the molten metal pump such that the gas outlet port
can transfer gas into the bottom of a flow of molten metal.
21. A gas-transfer foot for a molten metal pump, the gas-transfer
foot comprising: (a) a gas inlet port through which gas passes into
the foot; (b) a gas outlet port downstream from the gas inlet port,
wherein the gas-transfer foot is attachable to a component of the
molten metal pump such that the gas outlet port can transfer gas
into the bottom of a flow of molten metal.
22. A base for a molten metal pump, the base comprising: (a) a pump
chamber; (b) a discharge in fluid communication with the pump
chamber for discharging a molten metal stream, the discharge having
a bottom surface; (c) a gas-release opening on the bottom surface
of the discharge; and (d) a notch constructed in the base such that
an inserted gas-transfer foot is in communication with the
gas-release opening so that gas may be released into the
discharge.
23. The base of claim 22 wherein the discharge includes 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 greater than the first cross-sectional area.
24. The base of claim 23 wherein the gas-release opening is in
communication with the first section.
25. The base of claim 23 wherein the gas-release opening is in
communication with the second section.
26. The base of claim 23 wherein the discharge has sections in
addition to the first section and second section.
27. A metal-transfer conduit for a molten metal pump, the
metal-transfer conduit comprising: (a) an internal channel
extending therethrough, the channel having a bottom surface; (b) a
gas-release opening in the bottom surface of the channel; and (c) a
notch formed in the metal-transfer conduit, the notch configured to
receive a gas-transfer foot having a gas-outlet port such that when
the gas-transfer foot is received in the notch, the gas-outlet port
is in communication with the gas-release opening so that gas may be
released into the channel.
28. The metal-transfer conduit of claim 27 wherein the conduit path
includes 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 greater than the first cross-sectional
area.
29. The metal-transfer conduit of claim 28 wherein the gas-release
opening is in communication with the first section.
30. The metal-transfer conduit of claim 28 wherein the gas-release
opening is in communication with the second section.
31. The metal-transfer conduit of claim 28 wherein the conduit path
has sections in addition to the first section and second section.
Description
FIELD OF THE INVENTION
[0001] The invention relates to releasing gas into molten metal and
more particularly, to a device for releasing gas into the bottom of
a stream of molten metal that may utilize the flow of the molten
metal stream to assist in drawing the gas into the stream. In this
manner, the gas may be more effectively mixed into the molten
metal.
BACKGROUND OF THE INVENTION
[0002] As used herein, the term "molten metal" means any metal or
combination of metals in liquid form, such as aluminum, copper,
iron, zinc and alloys thereof. The term "gas" means any gas or
combinations of gases, including argon, nitrogen, chlorine,
fluorine, Freon, and helium, which are released into molten
metal.
[0003] Known pumps for pumping molten metal (also called "molten
metal pumps") include a pump base (also called a housing or
casing), one or more inlets, an inlet being an opening to allow
molten metal to enter a pump chamber (and is usually an opening in
the pump base that communicates with the pump chamber), a pump
chamber, which is an open area formed within the pump base, and a
discharge, which is a channel or conduit communicating with the
pump chamber (in an axial pump the pump chamber and discharge may
be the same structure or different areas of the same structure)
leading from the pump chamber to the molten metal bath in which the
pump base is submerged. A rotor, also called an impeller, is
mounted in the pump chamber and is connected to a drive shaft. The
drive shaft is typically a motor shaft coupled to a rotor shaft,
wherein the motor shaft has two ends, one end being connected to a
motor and the other end being coupled to the rotor shaft. The rotor
shaft also has two ends, wherein one end is coupled to the motor
shaft and the other end is connected to the rotor. Often, the rotor
shaft is comprised of graphite, the motor shaft is comprised of
steel, and the two are coupled by a coupling, which is usually
comprised of steel.
[0004] As the motor turns the drive shaft, the drive shaft turns
the rotor and the rotor pushes molten metal out of the pump
chamber, through the discharge, which may be an axial, tangential
or any type of discharge, and into the molten metal bath. Most
molten metal pumps are gravity fed, wherein gravity forces molten
metal through the inlet (either a top inlet, bottom inlet or both)
and into the pump chamber as the rotor pushes molten metal out of
the pump chamber.
[0005] Molten metal pump casings and rotors usually employ a
bearing system comprising ceramic rings wherein there is one or
more rings on the rotor that align with rings in the pump chamber
(such as rings at the inlet (which is usually at the top of the
pump chamber and/or bottom of the pump chamber) when the rotor is
placed in the pump chamber. The purpose of the bearing system is to
reduce damage to the soft, graphite components, particularly the
rotor and pump chamber wall, during pump operation. Known bearing
systems are described in U.S. Pat. Nos. 5,203,681, 5,591,243 and
6,093,000 to Cooper, the respective disclosures of which are
incorporated herein by reference. Further, U.S. Pat. No. 2,948,524
to Sweeney et al., U.S. Pat. No. 4,169,584 to Mangalick, U.S. Pat.
No. 5,203,681 to Cooper and U.S. Pat. No. 6,123,523 to Cooper (the
disclosure of U.S. Pat. No. 6,123,533 to Cooper is also
incorporated herein by reference) all disclose molten metal
pumps.
[0006] Furthermore, copending U.S. patent application Ser. No.
10/773,102 to Cooper, filed on Feb. 4, 2004 and entitled "Pump With
Rotating Inlet" discloses, among other things, a pump having an
inlet and rotor structure (or other displacement structure) that
rotate together as the pump operates in order to alleviate jamming.
The disclosure of this copending application is incorporated herein
by reference.
[0007] The materials forming the components that contact the molten
metal bath should remain relatively stable in the bath. Structural
refractory materials, such as graphite or ceramics, that are
resistant to disintegration by corrosive attack from the molten
metal may be used. As used herein "ceramics" or "ceramic" refers to
any oxidized metal (including silicon) or carbon-based material,
excluding graphite, capable of being used in the environment of a
molten metal bath. "Graphite" means any type of graphite, whether
or not chemically treated. Graphite is particularly suitable for
being formed into pump components because it is (a) soft and
relatively easy to machine, (b) not as brittle as ceramics and less
prone to breakage, and (c) less expensive than ceramics.
[0008] Three basic types of pumps for pumping molten metal, such as
molten aluminum, are utilized: circulation pumps, transfer pumps
and gas-release pumps. Circulation pumps are used to circulate the
molten metal within a bath, thereby generally equalizing the
temperature of the molten metal. Most often, circulation pumps are
used in a reverbatory furnace having an external well. The well is
usually an extension of a charging well where scrap metal is
charged (i.e., added).
[0009] Transfer pumps are generally used to transfer molten metal
from the external well of a reverbatory furnace to a different
location such as a ladle or another furnace. Examples of transfer
pumps are disclosed in U.S. Pat. No. 6,345,964 B1 to Cooper, the
disclosure of which is incorporated herein by reference, and U.S.
Pat. No. 5,203,681.
[0010] Gas-release pumps, such as gas-transfer pumps, circulate
molten metal while releasing a gas into the molten metal. In the
purification of molten metals, particularly aluminum, it is
frequently desired to remove dissolved gases such as hydrogen, or
dissolved metals, such as magnesium, from the molten metal. As is
known by those skilled in the art, the removing of dissolved gas is
known as "degassing" while the removal of magnesium is known as
"demagging." Gas-release pumps may be used for either of these
purposes or for any other application for which it is desirable to
introduce gas into molten metal. Gas-release pumps generally
include a gas-transfer conduit having a first end that is connected
to a gas source and a second submerged in the molten metal bath.
Gas is introduced into the first end and is released from the
second end into the molten metal. The gas may be released
downstream of the pump chamber into either the pump discharge or a
metal-transfer conduit extending from the discharge, or into a
stream of molten metal exiting either the discharge or the
metal-transfer conduit. Alternatively, gas may be released into the
pump chamber or upstream of the pump chamber at a position where it
enters the pump chamber. A system for releasing gas into a pump
chamber is disclosed in U.S. Pat. No. 6,123,523 to Cooper, and in
copending U.S. application Ser. No. 10/773,101 entitled System for
Releasing Gas Into Molten Metal filed on Feb. 4, 2004.
[0011] The advantage of a system for releasing gas into molten
metal within the confines of a metal-transfer conduit is that the
gas and metal should have a better opportunity to thoroughly
interact. One problem with releasing gas into a metal-transfer
conduit is that, in some systems, the conduit (called a
gas-transfer conduit) that transfers the gas from a gas source into
the molten metal stream typically extends into the metal-transfer
conduit, usually extending downward from the top of the
metal-transfer conduit, and disrupts the flow of molten metal
passing through the conduit and creating a low-pressure area behind
the portion of the gas-transfer conduit extending into the
metal-transfer conduit. The low-pressure area can interfere with
the released gas mixing with molten metal passing through the
metal-transfer conduit because, among other things, the gas
immediately rises into the low-pressure area instead of mixing with
molten metal throughout the metal-transfer conduit. This can create
a phenomenon known as "burping" because a large gas bubble will
build up in the low pressure area and then be released from the
discharge instead of thoroughly mixing with the molten metal.
SUMMARY OF THE INVENTION
[0012] The present invention includes a molten metal pump that
enables gas to be released into a stream of molten metal so that
the gas is mixed into the molten metal stream. The gas may be
released into an enclosed molten metal stream at location(s) within
the pump assembly, including at a stream within the pump discharge
and/or a stream within a metal-transfer conduit extending from the
pump discharge. The gas is released by a structure called a
"gas-transfer foot." The gas-transfer foot is positioned next to
and/or is attachable to the pump base and/or a metal-transfer
conduit extending from the pump base.
[0013] The discharge (pump base) and/or channel (metal-transfer
conduit) in which the gas is released may be comprised of two
sections: a first section having a first cross-sectional area and a
second section downstream from the first section having a second
cross-sectional area that is larger than the first cross-sectional
area. Preferably, the gas is released into or near the second
section so that the gas is released into an area of relatively
lower pressure.
[0014] The gas-transfer foot preferably includes a gas inlet port
through which gas enters the foot and a gas outlet port through
which gas exits the foot. The gas-transfer foot may be configured
to be attachable to a pump base and/or metal-transfer conduit such
that gas exiting the outlet port can enter the bottom of a stream
of molten metal. The gas-transfer foot is preferably coupled to a
gas-transfer tube to form a gas-transfer assembly. The gas-transfer
tube includes a first end connectable to the inlet port of the foot
and a second end connectable to a gas source.
[0015] For example, the gas-transfer foot may be attachable to a
base of a molten metal pump. In that case the gas-release opening
is preferably on the bottom surface of the discharge that is in
communication with either the first section, the second section, or
both the first and second sections.
[0016] The gas-transfer foot may also be attachable to a
metal-transfer conduit, which may extend form the pump discharge.
The metal-transfer conduit includes an inlet port, an outlet port,
a conduit, and a gas-release opening. The inlet port is in
communication with the base discharge. The outlet port is
downstream from the inlet port and is connected to the inlet port
via the conduit. The conduit preferably has a bottom surface and
includes a first section having a first cross-sectional area and a
second section having a second cross-sectional area. The second
section is downstream of the first section and the second
cross-sectional area is greater than the first cross-sectional
area. The opening is preferably positioned on the bottom surface of
the metal-transfer conduit and is in communication with either the
first section, the second section, or both the first and second
sections. The gas outlet port of the foot is in communication with
the opening in the metal so that gas can be transferred from the
gas outlet port through the opening and into the conduit.
[0017] The base of the molten metal pump configured to receive a
gas-transfer foot according to the invention. Such a base includes
a gas-transfer foot notch or ("notch") to receive the foot and
position it such that the gas exiting the gas-release opening in
the foot enters the molten metal stream in the pump base. The
opening is preferably on the bottom surface of the discharge and
enables gas to enter the bottom of the discharge. The notch is
preferably constructed so that gas-transfer foot is positioned so
that gas exiting the outlet port enters a relatively lower pressure
section of the molten metal stream.
[0018] The metal-transfer conduit may be configured to receive a
gas-transfer foot. The notch is preferably constructed so that the
gas outlet port of a gas-transfer foot is in communication with the
gas-release opening when the gas-transfer foot is inserted into the
notch.
[0019] Both the foregoing general description and the following
detailed description are exemplary and explanatory only and are not
restrictive of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1A depicts a molten metal pump according to one
embodiment of the invention.
[0021] FIG. 1B depicts a three support post variation of the molten
metal pump shown in FIG. 1A.
[0022] FIG. 1C depicts a bottom isometric view of a molten metal
pump according to one embodiment of the invention.
[0023] FIG. 2A depicts an isometric view of a base for a molten
metal pump according to one embodiment of the invention.
[0024] FIG. 2B depicts the discharge of a molten metal pump base
according to one embodiment of the invention.
[0025] FIG. 2C depicts a top isometric view of a pump base with a
gas-transfer foot notch according to one embodiment of the
invention.
[0026] FIG. 2D depicts a bottom isometric view of a pump base with
a gas-transfer foot notch according to one embodiment of the
invention.
[0027] FIG. 2E depicts a vertical cross-sectional view of a pump
base and attached gas-transfer assembly according to one embodiment
of the invention.
[0028] FIG. 2F depicts a horizontal cross-sectional view of a pump
base and attached gas-transfer foot according to one embodiment of
the invention.
[0029] FIG. 2G depicts a top-down horizontal cross-sectional view
of a pump base according to one embodiment of the invention.
[0030] FIG. 2H depicts an isometric horizontal cross-sectional view
of a pump base according to one embodiment of the invention.
[0031] FIG. 3A depicts a gas-transfer assembly according to one
embodiment of the invention.
[0032] FIG. 3B depicts an isometric view of a gas-transfer foot
according to one embodiment of the invention.
[0033] FIG. 3C depicts another isometric view of a gas-transfer
foot according to one embodiment of the invention.
[0034] FIG. 3D depicts a vertical cross-sectional view of a
gas-transfer foot according to one embodiment of the invention.
[0035] FIG. 4 is another embodiment of a molten metal pump
according to the invention.
[0036] FIG. 5A is an embodiment of a metal-transfer conduit
according to the present invention.
[0037] FIG. 5B is another embodiment of a metal-transfer conduit
according to the present invention.
[0038] FIGS. 6A-D show photographs of other views of metal-transfer
conduits and gas-transfer assemblies according to various aspects
of the invention
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0039] Reference will now be made in detail to the present
exemplary embodiments of the invention, examples of which are
illustrated in the accompanying drawings. FIG. 1A depicts a molten
metal pump 100 according to the invention. When in operation, pump
100 is typically positioned in a molten metal bath in a pump well,
which is typically part of the open well of a reverbatory furnace.
Pump 100 includes motor 120, superstructure 130, support posts 132,
drive shaft 122, rotor 110, base 200, gas-transfer foot 300 and
gas-transfer tube 350.
[0040] The components of pump 100 that are exposed to the molten
metal (such as support posts 132, drive shaft 122, rotor 110, base
200, gas-transfer foot 300 and gas-transfer tube 350) are
preferably formed of structural refractory materials, which are
resistant to degradation in the molten metal. Carbonaceous
refractory materials, such as carbon of a dense or structural type,
including graphite, graphitized carbon, clay-bonded graphite,
carbon-bonded graphite, or the like have all been found to be most
suitable because of cost and ease of machining. Such components may
be made by mixing ground graphite with a fine clay binder, forming
the non-coated component and baking, and may be glazed or unglazed.
In addition, components made of carbonaceous refractory materials
may be treated with one or more chemicals to make the components
more resistant to oxidation. Oxidation and erosion treatment for
graphite parts are practiced commercially, and graphite so treated
can be obtained from sources known to those skilled in the art.
[0041] Pump 100 need not be limited to the structure depicted in
FIG. 1A, but can be any structure or device for pumping or
otherwise conveying molten metal, such as the pump disclosed in
U.S. Pat. No. 5,203,681 to Cooper, or an axial pump having an
axial, rather than tangential, discharge. Preferred pump 100 has a
pump base 200 for being submersed in a molten metal bath. Pump base
200 preferably includes a generally nonvolute pump chamber 210,
such as a cylindrical pump chamber or what has been called a "cut"
volute, although pump base 200 may have any shape pump chamber
suitable of being used, including a volute-shaped chamber. Chamber
210 may be constructed to have only one opening, either in its top
or bottom, if a tangential discharge is used, since only one
opening is required to introduce molten metal into pump chamber
210. Generally, pump chamber 210 has two coaxial openings of the
same diameter and usually one is blocked by a flow blocking plate
mounted on, or formed as part of, rotor 110. Base 200 further
includes a tangential discharge 220 (although another type of
discharge, such as an axial discharge may be used) in fluid
communication with chamber 210. Base 200 will be described in more
detail below with reference to FIGS. 2A and 2B.
[0042] One or more support posts 132 connect base 200 to a
superstructure 130 of pump 100 thus supporting superstructure 130,
although any structure or structures capable of supporting
superstructure 130 may be used. Additionally, pump 100 could be
constructed so there is no physical connection between the base and
the superstructure, wherein the superstructure is independently
supported. The motor, drive shaft and rotor could be suspended
without a superstructure, wherein they are supported, directly or
indirectly, to a structure independent of the pump base.
[0043] In the preferred embodiment, post clamps 133 secure posts
132 to superstructure 130. A preferred post clamp and preferred
support posts are disclosed in a copending U.S. application Ser.
No. 10/773,118 entitled "Support Post System For Molten Metal
Pump," invented by Paul V. Cooper, and filed on Feb. 4, 2004, the
disclosure of which is incorporated herein by reference. However,
any system or device for securing posts to superstructure 130 may
be used.
[0044] A motor 120, which can be any structure, system or device
suitable for driving pump 100, but is preferably an electric or
pneumatic motor, is positioned on superstructure 130 and is
connected to an end of a drive shaft 122. A drive shaft 122 can be
any structure suitable for rotating an impeller, and preferably
comprises a motor shaft (not shown) coupled to a rotor shaft. The
motor shaft has a first end and a second end, wherein the first end
of the motor shaft connects to motor 120 and the second end of the
motor shaft connects to the coupling. Rotor shaft 123 has a first
end and a second end, wherein the first end is connected to the
coupling and the second end is connected to rotor 110 or to an
impeller according to the invention. A preferred coupling, rotor
shaft and connection between the rotor shaft and rotor 110 are
disclosed in a copending application entitled "Molten Metal Pump
Components," invented by Paul V. Cooper and filed on Feb. 4, 2004,
the disclosure of which is incorporated herein by reference.
[0045] The preferred rotor 110 is disclosed in a copending U.S.
Pat. application Ser. No. 10/773,102 to Cooper, filed on Feb. 4,
2004 and entitled "Pump With Rotating Inlet", the disclosure of
which is incorporated herein by reference. However, rotor 110 can
be any rotor suitable for use in a molten metal pump and the term
"rotor," as used in connection with this invention, means any
device or rotor used in a molten metal pump chamber to displace
molten metal.
[0046] Gas-transfer foot 300 and gas-transfer tube 350 combined
forms a gas transfer assembly 360. Gas-transfer foot 300 is
positioned next to (and may be attachable to) base 200 so that a
gas outlet port 320 (shown in FIG. 1B) of the gas-transfer foot is
in communication with a gas-release opening (not shown in FIG. 1A)
in the base. Gas is fed into the gas source end of gas-transfer
tube 350 which flows into the gas-transfer foot and then into the
flow of molten metal within base 200.
[0047] FIG. 1B depicts a variation of the molten metal pump shown
in FIG. 1A. The molten metal pump in FIG. 1B has three support
posts 132 rather than five. FIG. 1B also depicts the gas-releasing
opening 320 of gas-transfer foot 300 when the gas-transfer foot 300
is positioned next to and/or attached to base 200.
[0048] As shown in FIG. 1C, gas-transfer foot 300 may be positioned
next to molten metal pump 100 by inserting into a notch 214
constructed in base 200. In this way, the weight of the pump holds
the gas-transfer foot in place. Methods for positioning, securing
and/or attaching the gas-transfer foot next to the base need not be
limited to the notch shown in FIG. 1C. All that is needed is a
gas-transfer foot that may be positioned next to a molten metal
pump base such that gas flowing through the foot may enter into a
stream of molten metal flowing through the pump base and/or or a
conduit extending from the pump base.
[0049] FIG. 2A depicts an isometric view of a base for a molten
metal pump according to one embodiment of the invention. Base 200
has a top surface 218, a bottom surface 219, a first side 212, a
second side 214, a third side 215, a fourth side 216, and a fifth
side 217. The base need not be constructed with five sides, but may
be of any shape. Base 200 further includes one or more (and
preferably three) cavities 202, 204 and 206 for receiving support
posts 132. The cavities connect base 200 to support posts 132 such
that support posts 132 can support superstructure 130, and can help
to support the weight of base 200 when pump 100 is removed from a
molten metal bath. Any structure suitable for this purpose may be
used.
[0050] Base 200 also includes a discharge 220 that is in fluid
communication with chamber 210. A notch 214 allows for the
gas-transfer foot to be positioned next to the pump base. When in
position the gas-release opening of the gas-transfer foot is in
fluid communication with gas-release opening 230 such that gas may
introduced into a stream of molten metal traveling through
discharge 220.
[0051] As shown in FIG. 2B, discharge 220 has at least two sections
wherein at least one section (a first section) has a smaller
cross-sectional area than at least one other section (a second
section) downstream of the first section. Here, a first section 221
has a first cross-sectional area and a second section 222 is
downstream of first section 32 and has a second cross-sectional
area.
[0052] Section 221 is preferably about 1'' in length, 3'' in height
and 41/2'' in width for a pump utilizing a 10'' diameter rotor, and
has a substantially flat top surface 221A, a substantially flat
bottom surface 221B, a first radiused side surface 221C and a
second radiused side surface 221D. Section 221 defines a passage
through which molten metal may pass, and any shape or size passage
suitable for efficiently conveying molten metal may be used.
[0053] Second section 222 is preferably 10'' in length (although
any suitable length may be utilized) and has a top surface 222A
(shown in FIG. 2A), a bottom surface 222B, a first side surface
222C and second side surface 222D. Section 222 defines a passage
through which molten metal passes and any shape or size passage
suitable for efficiently conveying molten metal may be used.
Section 222 preferably has a height of about 4'' and width of about
51/2'' for a pump utilizing a rotor with a diameter of 10''.
Section 222 has a height of about 4'' and width of about 61/2'' for
a pump utilizing a rotor having a diameter of 16'', and preferably
has a cross-sectional area between about 110% and 350% larger than
the cross-sectional area of section 221. However, all that is
necessary for the proper functioning of the invention is that the
cross-sectional area of section 222 be sufficiently larger than the
area of section 221 to reduce the amount of pressure required for
gas to be released into the molten metal stream as compared to the
pressure required to release gas into a metal-transfer conduit that
has substantially the same cross-sectional area throughout.
[0054] Alternatively, discharge 220 or any metal-transfer conduit
in accordance with the invention could have multiple
cross-sectional areas, as long as there is a transition from a
first section with a first cross-sectional area to a second section
with a second cross-sectional area, wherein the second section is
downstream of the first section and the second cross-sectional area
is greater than the first cross-sectional area. It is preferred
that there be an abrupt transition from the first section having a
first cross-sectional area to a second section having a second,
larger cross-sectional area, however, the transition may be
somewhat gradual, taking place over a length of up to 6'' or
more.
[0055] Preferably, a gas-release opening 230 is formed in second
section 222 through bottom surface 219 of base 200. However,
gas-release opening 230 may also be formed in a top or side section
of base 200. Gas-release opening 230 is any size suitable for
releasing gas from an opening in gas-transfer foot 300 into
discharge 220. It is preferred that gas-release opening 230 be
formed outside of the higher-pressure flow of the molten metal
stream (such as in section 222), but it can be positioned anywhere
suitable for releasing gas into discharge 220. For example, as
shown in FIG. 2B gas-release opening 230 may be formed in second
section 222 near (preferably within 3'') first section 221.
However, all that is necessary for the proper functioning of the
invention is that there be (1) a first section for transferring a
molten metal stream having a first cross-sectional area and a
second section downstream of the first section, wherein the second
section has a second cross-sectional area larger than the first
section, and (2) a gas-release opening in the first section and/or
the second section (preferably in or near the bottom surface of
either section), whereby the respective sections are configured and
the gas-release openings is positioned so that less pressure is
required to release gas into the molten metal than would be
required in known metal-transfer conduits that have substantially
the same cross-sectional area throughout. Thus, in addition to a
gas-release opening being formed in the first section or the second
section, a gas-release opening could be formed in the first section
and another gas-release opening could be formed in the second
section, and gas could be released into each section, or into one
section or the other.
[0056] FIGS. 2C and 2D show gas-transfer foot notch 240 for
attachment of a gas-transfer foot. The notch is shaped so as to
accept the gas-transfer foot 300 (described below) and is
preferably positioned in the bottom surface of base 200 so that the
weight of the base secures gas-transfer foot 300 when it is
inserted into notch 240. Though not required, the gas-transfer foot
may be cemented in place or otherwise secured to the base in any
suitable manner. As shown, notch 240 includes one angled side to
accept a gas-transfer foot with an angled side. However, any shape
notch is suitable as long as it is configured to properly position
the gas-transfer foot so that gas released from the gas-release
opening of the gas-transfers enters into the molten metal stream
when the gas-transfer foot is inserted into the notch. In addition,
pump base 200 may also include a tube notch 241 so that
gas-transfer tube 350 may be positioned closer to pump base 200 and
be held more firmly in place.
[0057] FIGS. 2E-F show cross-sectional views of a pump base with
and without an attached gas-transfer foot. FIG. 2E depicts a
vertical cross-sectional view of a pump base and attached
gas-transfer assembly. FIG. 2F depicts a horizontal cross-sectional
view of a pump base and attached gas-transfer foot. FIG. 2G depicts
a top-down horizontal cross-sectional view of a pump base. FIG. 2H
depicts an isometric horizontal cross-sectional view of a pump
base.
[0058] FIG. 3 depicts a gas-transfer assembly 360 according to the
invention. The gas-transfer assembly 360 includes gas-transfer foot
300 and gas-transfer tube 350. Gas-transfer foot 300 includes a gas
outlet port 320 which is in fluid communication with gas-release
opening 230 (see FIGS. 2A-H) when the foot is positioned next to
and/or attached to the base. The gas outlet port may be any size
that allows for the release of gas into a stream of molten metal,
and is preferably at least 1/2 inch in diameter.
[0059] Gas-transfer tube 350 is preferably a cylindrical, graphite
tube having a first end 351 (connectable to a gas source) and a
second end 352 (for connecting to the gas-transfer foot) and a
passage extending therethrough. Preferably second end 352 is
threaded so as to provide a secure fit into the threaded hole of
gas inlet port 310. However, any structure capable of transferring
gas from a gas source (not shown) to gas-transfer foot according to
the invention may be used.
[0060] As depicted in FIGS. 3B and 3C, gas-transfer foot 300 has a
top surface 308, a bottom surface 310, and sides 301, 302, 305, 306
and 307. As shown, side 306 is angled so as to fit into notch 240
as described above. However, the gas-transfer foot need not be
shaped as depicted (it could have more or fewer sides and be of any
suitable shape), but preferably is shaped so that it is received
into a notch in the base of a molten metal pump or metal-transfer
conduit to be positioned such that gas released from the foot
passes into the molten metal stream in either the base or
metal-transfer conduit. Gas-transfer foot 300 also includes gas
inlet port 310 through which gas enters the foot from gas-transfer
tube 350. In this embodiment, gas inlet port 310 is shown to be
threaded to accept a threaded end of gas-transfer tube 350.
However, any method for attaching the gas-transfer tube to the
gas-transfer foot may be used so long as gas is able to flow from
the tube into the foot.
[0061] As shown in FIG. 3D, gas inlet port 310 is in fluid
communication with gas outlet port 320. Gas inlet port 310 may be
of any size that allows for connection with gas-transfer tube 350,
and is preferably at least a 1/2 inch diameter opening.
[0062] FIG. 4 depicts a molten metal pump according to a second
embodiment of the invention. In this embodiment pump 400 includes a
metal-transfer conduit 500 and a base 600. The remaining components
are the same as described above with reference to pump 100. In this
embodiment, metal-transfer conduit 500 is in communication with the
discharge of base 600 so that the stream of molten metal flows
through the conduit. A gas-transfer foot is insertable into the
metal-transfer conduit so that gas is released into the bottom of
the stream of molten metal within the conduit.
[0063] Base 600 is similar to base 400 except that base 600 need
not have a gas-release opening or a gas-transfer foot notch.
However, a base with a gas-release opening and notch in which a
gas-transfer foot is inserted may be used in conjunction with the
metal-transfer conduit so that gas may be released into the steam
of molten metal at both the base and the conduit.
[0064] FIG. 5A depicts a metal-transfer conduit according to the
invention. Metal-transfer conduit 500 includes inlet port 501 and
outlet 502. The inlet port and outlet port are in fluid
communication via conduit path 504. Conduit path 504 has at least
two sections wherein at least one section (a first section) has a
smaller cross-sectional area than at least one other section (a
second section) downstream of the first section. Here, a first
section 505 has a first cross-sectional area and a second section
506 is downstream of first section 505 and has a second
cross-sectional area.
[0065] Section 505 is preferably about 1'' in length, 3'' in height
and 41/2'' in width for a pump utilizing a 10'' diameter rotor, and
has a substantially flat top surface, a substantially flat bottom
surface, a first radiused side surface and a second radiused side
surface. Section 505 defines a passage through which molten metal
may pass, and any shape or size passage suitable for efficiently
conveying molten metal may be used.
[0066] Second section 506 is preferably 10'' in length (although
any suitable length may be utilized) and has a top surface, a
bottom surface, a first side surface and second side surface.
Section 506 defines a passage through which molten metal passes and
any shape or size passage suitable for efficiently conveying molten
metal may be used. Section 506 preferably has a height of about 4''
and width of about 51/2'' for a pump utilizing a rotor with a
diameter of 10''. Section 506 has a height of about 4'' and width
of about 61/2'' for a pump utilizing a rotor having a diameter of
16'', and preferably has a cross-sectional area between about 110%
and 350% larger than the cross-sectional area of section 505.
However, all that is necessary for the proper functioning of the
invention is that the cross-sectional area of section 506 be
sufficiently larger than the area of section 505 to reduce the
amount of pressure required for gas to be released into the molten
metal stream as compared to the pressure required to release gas
into a metal-transfer conduit that has substantially the same
cross-sectional area throughout.
[0067] Alternatively, conduit path 504 could have multiple
cross-sectional areas, as long as there is a transition from a
first section with a first cross-sectional area to a second section
with a second cross-sectional area, wherein the second section is
downstream of the first section and the second cross-sectional area
is greater than the first cross-sectional area. It is preferred
that there be an abrupt transition from the first section having a
first cross-sectional area to a second section having a second,
larger cross-sectional area, however, the transition may be
somewhat gradual, taking place over a length of up to 6'' or
more.
[0068] A gas-release opening 508 is formed in second section 506
through the bottom surface metal-transfer conduit 500. Gas-release
opening 508 is any size suitable for releasing gas from an opening
in gas-transfer foot 300 into conduit path 504. It is preferred
that gas-release opening 508 be formed outside of the high-pressure
flow of the molten metal stream (such as in section 506), but it
can be positioned anywhere suitable for releasing gas into conduit
path 504. For example, as shown in FIG. 5B gas-release opening 508
may be formed in first section 505 near (preferably within 3'')
second section 506. All that is necessary for the proper
functioning of the invention is that there be (1) a first section
of a metal-transfer conduit having a first cross-sectional area and
a second section of the metal-transfer conduit downstream of the
first section, wherein the second section has a second
cross-sectional area larger than the first section, and (2) a
gas-release opening in the bottom surface of the first section
and/or the second section, whereby the respective sections are
configured and the gas-release openings is positioned so that less
pressure is required to release gas into the molten metal than
would be required in known metal-transfer conduits that have
substantially the same cross-sectional area throughout. Thus, in
addition to a gas-release opening being formed in the first section
or the second section, a gas-release opening could be formed in the
first section and another gas-release opening could be formed in
the second section, and gas could be released simultaneously into
each section, or into one section or the other.
[0069] Metal-transfer conduit 500 also includes a gas-transfer foot
notch 509 for attachment of a gas-transfer foot. The notch is
shaped so as to accept the gas-transfer foot. Preferably, notch 509
is positioned in the bottom surface of metal-transfer conduit 500
so that the weight of the conduit secures the gas-transfer in
position. Though not required, the foot may be cemented in place or
otherwise be maintained in place by any suitable means As with the
notch in the pump base, notch 509 may includes one angled side to
accept a gas-transfer foot with an angled side. However, any shape
notch is suitable as long as the gas-transfer foot is secure when
inserted into the notch. In addition, notch 509 should be
constructed so that the gas outlet port of the gas-transfer foot is
in communication with the gas-release opening when the gas-transfer
foot is inserted into the notch.
[0070] FIGS. 6A-D show photographs of other views of metal-transfer
conduits and gas-transfer assemblies according to various aspects
of the invention.
[0071] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims.
* * * * *