Metallurgical apparatus – Process – Tuyere operation
Reexamination Certificate
1999-04-02
2001-01-09
Kastler, Scott (Department: 1742)
Metallurgical apparatus
Process
Tuyere operation
C266S225000, C266S268000
Reexamination Certificate
active
06171544
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to the flow of gas. The invention enables the flow of more than one gas stream from a single lance such that the gas streams flow proximate to one another for an extended distance while remaining distinct.
BACKGROUND ART
It is often desired to establish a flow of gas. For example, a flow of gas may be injected into a liquid for one or more of several reasons. A reactive gas may be injected into a liquid to react with one or more components of the liquid, such as, for example, the injection of oxygen into molten iron to react with carbon within the molten iron to decarburize the iron and to provide heat to the molten iron. Oxygen may be injected into other molten metals such as copper, lead and zinc for smelting or refining purposes or into an aqueous liquid or hydrocarbon liquid to carry out an oxidation reaction. A non-oxidizing gas, such as an inert gas, may be injected into a liquid to stir the liquid in order to promote, for example, better temperature distribution or better component distribution throughout the liquid.
Sometimes it is desirable to have the gas stream flow for an extended distance at a high velocity such as a supersonic velocity. This can be done by surrounding the gas stream in a flame envelope. The flame envelope keeps ambient gas from aspirating into the gas stream and this leads to the establishment of a coherent gas stream which can flow for an extended distance without any significant decrease in the gas stream velocity or significant increase in the diameter of the gas stream.
It is often desirable to use more than one gas stream in an operation. The gas could be the same for all the gas streams, or different gases could be used for one or more of the gas streams. For example, in electric arc furnace practice or basic oxygen furnace practice it is sometimes preferable to inject oxygen into the molten metal at two or more locations rather than at a single location. Moreover, in electric arc furnace practice it may be desirable to use one or more gas streams for gas injection into the molten metal and, in addition, one or more gas streams to provide oxygen into the head space of the furnace vessel for post combustion.
When in such multiple gas stream practice it is desired that the gas streams also be coherent, this has heretofore been accomplished by using a separate injection lance for each gas stream whereby the gas streams and the fluids for the corresponding flame envelopes for each of the gas streams are provided. While such a system using multiple lances effectively provides multiple coherent gas streams, it is costly and difficult to use. These problems increase as the number of individual lances increases.
Accordingly, it is an object of this invention to provide a system for establishing multiple coherent jets wherein only a single injection lance is required.
SUMMARY OF THE INVENTION
The above and other objects, which will become apparent to one skilled in the art upon a reading of this disclosure, are attained by the present invention, one aspect of which is:
A method for establishing multiple coherent gas jets from a single lance comprising:
(A) providing a lance having an end with a plurality of nozzles, each of said nozzles having an output opening for ejecting gas from the nozzle;
(B) passing gas in a jet out from each nozzle output opening and forming a plurality of gas jets, each gas jet flowing from a nozzle output opening;
(C) passing fuel and oxidant in at least one stream out from the lance end and combusting the said fuel with the said oxidant to form a flame envelope around the plurality of gas jets; and
(D) maintaining the flow of each gas jet distinct for the length of said gas jet.
Another aspect of the invention is:
A lance for establishing multiple coherent gas jets comprising:
(A) a lance having an end with a plurality of nozzles, each said nozzle having an input opening and an output opening;
(B) each said nozzle input opening communicating with a source of gas, and each said nozzle output opening disposed on the face of the lance end;
(C) at least one ejection means at the lance end face around the plurality of nozzle output openings; and
(D) an extension extending from the lance end face forming a volume with which each of the plurality of nozzle output openings and the ejection mean(s) communicates.
Another aspect of the invention is:
A method for establishing multiple coherent gas jets from a single lance comprising:
(A) providing a lance having an end with a plurality of nozzles, each of said nozzles having an output opening for ejecting gas from the nozzle;
(B) passing gas in a jet out from each nozzle output opening and forming a plurality of gas jets, each gas jet flowing from a nozzle output opening;
(C) passing fuel in at least one stream out from the lance end around the plurality of gas jets and combusting the said fuel with air entrained into the fuel stream(s) to form a flame envelope around the plurality of gas jets; and
(D) maintaining the flow of each gas jet distinct for the length of said gas jet.
As used herein the term “annular” means in the form of a ring.
As used herein the term “flame envelope” means a combusting stream coaxially around at least one other gas stream.
As used herein the term “length” when referring to a gas jet means the distance from the nozzle from which the gas is ejected to the intended impact point of the gas jet.
As used herein the term “distinct” when referring to a gas jet means without significantly interacting with another gas jet.
As used herein the term “contained oxygen flowrate” means the oxidant flowrate times the percent oxygen in the oxidant divided by 100. For example, 10,000 CFH pure oxygen has 10,000 CFH contained oxygen and 10,000 CFH air has about 2,100 CFH contained oxygen.
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Stoecker et al., “Fundamental Concepts of Oxygen Cutting”, AWS Fall Meeting, Cleveland, Ohio (Dec. 1957).
Anderson John Erling
Farrenkopf Dennis Robert
Mahoney William John
Mathur Pravin Chandra
Semenza Richard Thomas
Kastler Scott
Ktorides Stanley
Praxair Technology Inc.
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