Patent Application
20100035194
The invention pertains to a burner arrangement for heating or keeping hot especially the pouring stream shielding and/or submerged nozzle devices of especially a continuous casting plant.
In melting operations such as those in steel works with continuous casting plants, the molten, liquid metal is usually carried by a ladle to the pouring stand of a continuous casting plant. The molten metal flows out of the ladle through a pouring stream shield, such as a ladle shroud, into a distributor. From the distributor, the metal flows through a submerged nozzle or immersion nozzle into the mold of the continuous casting plant. The immersion nozzle and possibly the ladle shroud are preheated before the start of casting, whereas they are usually not heated during the casting operation itself. To heat them, a burner is operated with fossil fuel such as natural gas and with an oxygen carrier such as air. The standard approach is to use commercially available burners to heat a container, in which the immersion nozzle or the ladle shroud are placed. In the case of another known example, the flame of the burner is used to heat the ladle shroud or the immersion nozzle directly, without the intermediate presence of a container.
Through the use of standard commercial burners which produce flames, a fast-moving exhaust gas is produced, which causes streaks during the heating of the immersion nozzle or ladle shroud, and which overall comprises a small amount of radiant energy. The flame heats only small areas of the ladle shroud or immersion nozzle to be heated, which can lead to local overheating in the areas where the flame acts directly on the nozzle, whereas other areas farther away from the flame tend not to be heated enough. As a result, stresses are caused in the immersion nozzle or ladle shroud, which can lead to cracking and thus to the shutdown of the entire plant. Heating with the flame of a standard commercial burner, furthermore, consumes a large amount of energy, and large amounts of CO2 are also emitted. The cost of providing energy is therefore high, and this makes it uneconomical to operate the plant. In addition, very large amounts of combustion gases are discharged, which is relatively unfriendly to the environment overall. This is now being felt to be especially disadvantageous within the context of the greenhouse effect.
Burners of this type are known from, for example, JP 61262455 A, EP 0 775 543 B1, EP 0 495 764 B1, and KR 1020050114398 A.
Electrical heating, furthermore, is known from JP 10118746 and DE 196 51 533 C2. Electrical heating, however, suffers from the disadvantage that the efficiency is highly unfavorable. The primary energy demand is therefore relatively high, and thus the method is not very economical.
The goal of the invention is to create a burner arrangement for heating or keeping hot especially the pouring stream shielding and/or immersion nozzle devices especially of a continuous casting plant, which achieves improved utilization of the energy input, reduces the emission of CO2, and ensures the high availability of the plant. It is also the goal of the invention to create a method for the advantageous control of a burner arrangement.
The goal with respect to the burner arrangement is achieved with a burner arrangement especially for the heating or keeping hot of especially the pouring stream shielding and/or immersion nozzle devices of a continuous casting plant with a container, which can hold in particular a ladle shroud or an immersion nozzle, wherein at least part of the wall of the container is formed by at least one porous burner.
According to the invention, it is advantageous for the porous burner to comprise preferably a plurality of porous burner segments. These are then connected to each other to form the porous burner, or they can be designed as an integral or one-piece unit.
It is also especially advantageous for the porous burner segments of the porous burner to form rings and/or rows arranged in the axial direction. It is also advantageous for the porous burner to consist of porous burner segments, wherein a plurality of segments forms rings or rows extending in the circumferential direction. In the case of an exemplary embodiment of the invention, it is advisable for the porous burner segments of the porous burner to form a hexagonal or octagonal arrangement when seen in the axial direction.
It is also advantageous for the container to comprise a bottom and/or a cover, consisting of a bottom plate and/or a cover plate.
With respect to the design of the burner arrangement, it is also advantageous for the porous burner segments to be supplied individually with fuel through separate feed lines, especially in a manner proceeding radially from the outside. For this purpose, the feed lines can extend radially outward from the segments and possibly have an additional feed line section extending in the axial direction.
With respect to the fuel supply, it is advantageous for at least certain individual feed lines to be supplied with fuel by way of a common supply line. It can be advisable here for the supply line or supply lines to be designed in an essentially ring-shaped manner and for them to be connected to the feed lines. The ring does not have to be completely closed, wherein it can also be advantageous for the ring to be closed.
The goal with respect to the method for controlling a burner arrangement is achieved in that porous burner segments are either turned on or turned off as a function of the desired heating intensity or heat output. It can be advantageous to turn on or to turn off at least every other segment of a ring of segments extending around the circumference of the porous burner. As a result, it is possible to arrive at the advantageous result that the operating and nonoperating segments are distributed uniformly around the circumference. It is also advisable to turn on or to turn off segments of rings or rows of porous burner segments which are adjacent to each other or farther apart in the axial direction of the porous burner. This makes it possible to achieve the advantageous result that the operating and nonoperating segments are distributed uniformly over the axial length of the burner arrangement.
Advantageous elaborations are described in the subclaims.
The invention is described in greater detail below on the basis of an exemplary embodiment, which is illustrated in the drawings:
The porous burner 3 shown in
The immersion nozzle is also arranged in a container 5, which advantageously is thermally insulated, and which advantageously is formed by the two plates 6, 7, i.e., a bottom plate and a cover plate, and the wall 8 is formed by the segments 3a, 3b, 3c, 3d of the porous burner 3, which are arranged around the outside circumference. The segments are arranged adjacent to each other with only narrow joints between them, so that, in cross section, a multi-row arrangement of porous burners is formed.
As
The porous burner 3 produces a hot exhaust gas stream 9 and radiant heat 10, which are directed toward the immersion nozzle to heat it, to warm it, or to temper it to the desired temperature. The hot exhaust gas arrives in the heating space of the interior of the container 5 at relatively low velocity, which brings about a homogeneous temperature distribution in the interior of the container 5 and thus counteracts the tendency of streaks to form. But because, in addition, a large percentage of the energy is converted to radiant energy, the immersion nozzle can also be heated very effectively.
It is especially advantageous to design the porous burner as an essentially ring-shaped or tubular arrangement, wherein the arrangement is assembled from individual porous burner segments. As a result, it is possible advantageously to operate in a controlled manner, in that individual segments or rows or rings of segments are turned on or off independently of each other or in that individual segments are turned on or off independently of each other.
All of the porous burner segments will be turned on or individual segments will be turned off as a function of the heating intensity or heat output to be provided. It can be advantageous to turn on or to turn off at least every other segment of a ring extending around the circumference. It can also be advantageous to turn on or to turn off at least every other ring of segments arranged in the axial direction of the immersion nozzle.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2007 016 018.8 | Apr 2007 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2008/001570 | 2/28/2008 | WO | 00 | 10/2/2009 |
