Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Reexamination Certificate
2002-06-19
2004-10-12
Kastler, Scott (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
C266S225000, C266S268000
Reexamination Certificate
active
06802887
ABSTRACT:
The invention relates to a method for feeding a gas into a metallurgical vessel, a condensable and/or evaporable component in the gaseous and/or liquid state being entrained by the gas, and the gas being fed to the metallurgical vessel via one or more gas supply means, and to a gas supply means for carrying out the method.
Metallurgical vessels, in particular melter gasifiers, are fed an oxygen-containing gas, for example air or oxygen-enriched air or technical-grade oxygen, via gas nozzles. For process control purposes and to influence the method, it is necessary for a condensable or evaporable component to be blown into the metallurgical vessel together with the corresponding gas. This component is generally formed by water or steam.
A melter gasifier is fed with steam in order to allow the flame temperatures at the oxygen nozzles to be influenced. Since steam is not always available, a further possibility is to supply liquid water in atomized form. In the case of water in the liquid state, as well as the endothermic gasification reaction (H
2
O+C==>H
2
+CO) which takes place in any case, the heat of evaporation which is to be applied after the water has been blown in additionally serves to influence the temperature.
However, with both measures there is a risk of water which has condensed or is still liquid flowing through the nozzle passage to the refractory material of the melter gasifier, where it can damage the masonry work. Early atomization does not solve this problem, since the water constantly reaches the inner wall of the nozzle passage, where it forms a film of water.
Therefore, the object of the present invention is to provide a method, of feeding gas which contains a condensable and/or evaporable component in the gaseous and/or liquid state entrained therein in which possible damage to the gas supply means is considerably reduced or prevented altogether.
This object is achieved by the fact that if there are a number of the gas supply means, in each of these gas supply means
in a first section the gas velocity is continuously increased,
in a turbulence zone the gas is intimately mixed with the condensable and/or evaporable component, and
the gas which has been intimately mixed with the entrained component is blown into the metallurgical vessel.
If the component is originally used in the gaseous state, the method according to the invention reliably makes it possible to distribute liquid which has condensed out of the gas phase uniformly in the gas stream, since it is no longer possible for a film of liquid to be deposited in the turbulence zone. The flow conditions and temperatures which then prevail mean that it is also no longer possible for a film of liquid to be deposited again downstream of the turbulence zone.
The method according to the invention also allows the component to be used in the liquid state, for example to be sprayed into the gas stream. Costs can be saved by the absence of a separate evaporation step.
A preferred embodiment of the method according to the invention consists in the gas being formed by oxygen, in particular technical-grade oxygen, as is obtained, for example, from an air fractionation installation.
The condensable and/or evaporable component is preferably formed by steam or water.
According to a further advantageous embodiment, the gas velocity downstream of the first section and upstream of the turbulence zone is kept substantially constant for a period of time.
According to another advantageous embodiment, the gas velocity upstream of the first section is kept substantially constant for a period of time.
According to another embodiment, the gas velocity is kept substantially constant or falls slightly over the exit section.
The invention also relates to a gas supply means for feeding a gas into a metallurgical vessel, the gas supply means having a flow passage passing through it along a central longitudinal axis, and a condensable or evaporable component being entrained by the gas.
In this gas supply means, the intention is to considerably reduce or prevent altogether any possible damage during operation.
To achieve this object, according to the invention a gas supply means of this type is characterized in that the flow passage—starting from a defined cross section—has at least
an abrupt cross-sectional widening in the flow passage, and
an exit section which is arranged downstream of the cross-sectional widening, as seen in the direction of flow of the gas, and
a narrowing section, which has a cross section of flow which narrows in the direction of flow of the gas, being arranged upstream of the cross-sectional widening in the direction of flow of the gas.
In this context, an abrupt cross-sectional widening is to be understood as meaning a sudden increase in the diameter of the flow passage which takes place in the direction of flow of the gas. As a result of the swirling and turbulence which occur in the gas, gas constituents which were not fully mixed with the gas by this point are intimately mixed with the gas. In addition, any liquid deposits on the inner wall of the flow passage are entrained thereby and are likewise distributed uniformly in the gas.
Neither for the method according to the invention nor for the gas supply means according to the invention is it necessary for all the sections of a gas supply means mentioned above and below to be structurally combined in a nozzle.
For example, it is possible for the first section or the narrowing section to be arranged upstream of the nozzle and for the exit section to be arranged downstream of the nozzle. The reduced service life of the nozzle and/or the refractory material resulting from this less optimal arrangement may nevertheless be adequate for certain applications. Thus, it should be understood that the gas supply means according to the invention is to be regarded in the most general sense as a gas supply system including one or more gas supply devices having operational characteristics as described herein, and to be inclusive of all physical realizations by which these operating characteristics are realized, in addition to those specifically described.
According to an advantageous configuration, an intermediate section of substantially constant cross section of flow is arranged between the narrowing section and the abrupt cross-sectional widening.
This intermediate section means that the abrupt cross-sectional widening is situated at an optimum distance—with a view to achieving optimum turbulence and to avoiding a film of liquid in the exit section—from the gas supply means opening which is on the melter gasifier side.
The abrupt cross-sectional widening is advantageously refined in such a manner that the increase in the cross section of flow at the abrupt cross-sectional widening has a mean inclination &agr;—with respect to the longitudinal axis of the flow passage—of at least 60°, preferably of at least 75°.
With an inclination a of at least 60°, a step is formed on the inner wall of the flow passage, ensuring sufficient atomization of deposited or entrained liquid and then sufficient turbulence and mixing of the gas components.
It is particularly advantageous if the increase in the cross section of flow at the abrupt cross-sectional widening has a mean inclination &agr; of substantially 90°.
90° does not represent the maximum upper limit for the inclination &agr;; higher values for &agr; under certain circumstances lead to expedient embodiments. Although higher values for &agr; result in a sharper break-off edge, if &agr;>90° this edge becomes worn more easily than if &agr;≦90°.
According to one embodiment of the gas supply means according to the invention, an entry section of substantially constant cross section of gas flow is arranged upstream of the narrowing section, as seen in the direction of flow of the gas.
A further aspect of the present invention relates to a device for feeding a gas into a metallurgical vessel, the device comprising one or more gas supply means according to the invention, as well as gas feed lines leadin
El-Rayes Mohamed Tarek
Wieder Kurt
Wurm Johann
Kastler Scott
Ostrolenk Faber Gerb & Soffen, LLP
Voest-Alpine Industrieanlagenbau GmbH & Co.
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