Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Reexamination Certificate
1999-10-12
2001-07-17
Andrews, Melvyn (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
C075S531000, C266S222000, C266S225000
Reexamination Certificate
active
06261338
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to coherent jet technology and also to powder injection.
BACKGROUND ART
A recent significant advancement in the field of gas dynamics is the development of coherent jet technology which produces a laser-like jet of gas which can travel a long distance while still retaining substantially all of its initial velocity and with very little increase to its jet diameter. One very important commercial use of coherent jet technology is for the introduction of gas into liquid, such as molten metal, whereby the gas lance may be spaced a large distance from the surface of the liquid, enabling safer operation as well as more efficient operation because much more of the gas penetrates into the liquid than is possible with conventional practice where much of the gas deflects off the surface of the liquid and does not enter the liquid.
Often in the practice of industrial processes such as metal refining, it is desired to inject powder into the liquid, e.g. molten metal. Such powder injection can be from either below or above the liquid surface, although above-surface injection is generally preferred because it is inherently easier and generally also safer. Typically above-surface powder injection is practiced by entraining powder into a carrier gas and providing the carrier gas from an injector device into the liquid. Where coherent jet technology is employed to provide gas into a liquid, powder injection may also be practiced using the known powder injector device.
It would be desirable to use the same lance to generate the coherent gas jet and also for practice of powder injection. However such a system is not a straightforward combination of the two systems because the proximate practice of these two technologies can have a detrimental effect to the efficacy of each.
Accordingly it is an object of this invention to provide a system whereby a single lance may be effectively used to practice coherent jet technology for gas injection into a liquid, and also to practice powder injection for the provision of powder into the liquid.
SUMMARY OF THE INVENTION
The above and other objects, which will become apparent to those skilled in the art upon a reading of this disclosure, are attained by the present invention, one aspect of which is:
A method for delivering both powder and gas to a liquid comprising:
(A) ejecting gas from a lance through a gas opening on the face of the lance to form a gas stream;
(B) ejecting a mixture of powder and carrier gas from the lance through a powder mixture opening on the face of the lance, said powder mixture opening being spaced from the gas opening, to form a powder mixture stream;
(C) forming a flame envelope around both the gas stream and the powder mixture stream; and
(D) passing the gas stream and the powder mixture stream from the lance face to the liquid.
Another aspect of this invention is:
Apparatus for providing both powder and gas to a liquid comprising:
(A) a lance having a lance face;
(B) a gas passage within the lance, said gas passage communicating with a source of gas and also communicating with a gas opening on the lance face;
(C) a powder mixture passage within the lance, said powder mixture passage communicating with a source of powder and carrier gas and also communicating with a powder mixture opening on the lance face, said powder mixture opening being spaced from the gas opening; and
(D) means for providing gaseous fuel and oxidant out from the lance in a ring around the gas opening and the powder mixture opening.
As used herein the term “coherent jet” means a gas jet which is formed by ejecting gas from a nozzle and which has a velocity and momentum profile along its length which is similar to its velocity and momentum profile upon ejection from the nozzle.
As used herein the term “annular” means in the form of a ring.
As used herein the term “flame envelope” means an annular combusting stream substantially coaxial with at least one gas stream.
As used herein the term “length” when referring to a coherent gas jet means the distance from the nozzle from which the gas is ejected to the intended impact point of the coherent gas jet or to where the gas jet ceases to be coherent.
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Anderson John Erling
Mahoney William John
Andrews Melvyn
Ktorides Stanley
Praxair Technology Inc.
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