Sub-lance installation for carrying out measurements and/or taking samples in a metallurgical furnace

#1. Field of the Invention

#The invention relates to a sub-lance installation for carrying out measurements and/or taking samples in a metallurgical furnace, comprising an elongate tubular lance which is rotatable around its longitudinal axis and which is attached at its upper end to a carriage by which the lance with its longitudinal axis vertical is moved vertically to bring its lower end to an operational location for measurement and/or sample-taking.

#The invention will be described in particular for application in a steel converter of the type in which liquid pig iron is made into steel by blowing in oxygen from above through a main lance onto the pig iron bath, but the invention is not limited to this application. Applications of the invention are possible in metallurgical processes in other types of metallurgical furnace.

#A preferred embodiment of the invention will now be described by way of non-limitative example, with reference to the accompanying drawings, in which:

#FIGS. 1a and 1b are schematic views of a sub-lance at various phases in its use,

#FIG. 2 shows the preferred embodiment of means for rotating a sub-lance in a sub-lance installation according to the invention.

#FIGS. 1a and 1b show a main lance 1 which blows oxygen onto a metal bath 2. Parallel with the oxygen lance 1 is a sub-lance 3 shown in its lowest position, in which a probe 5 at its lower end extends into the bath. The sub-lance 3 is an elongate tubular structure and has its longitudinal axis vertical. At the top end of the sub-lance 3 suspension means 4 are fitted which suspend the sub-lance in a carriage by which the sub-lance can be moved upwards and downwards along a guide path. An inlet 6 and outlet 7 for cooling liquid are arranged near the top end, through which the sub-lance can be cooled almost as far as the attachment for the probe 5 by means of liquid flowing through it.

#The sub-lance 3 is of the rotable type and in FIGS. 1 and 2 is shown in an embodiment such as is known from U.S. Pat. No. 4,438,653. The outer sheath 10 of the sub-lance is divided, the two parts being joined to each other by the coupling halves 8 and 9. The coupling halves 8 and 9 are rotatable with respect to each other and provided with a seal in order to prevent leakage of the cooling liquid. The invention can however not only be applied to this embodiment of a sub-lance, but also to other embodiments, for example to the rotatable sub-lance such as is known from U.S. Pat. No. 4,141,249.

#In FIG. 1a the position of the sub-lance for blowing of oxygen onto the bath is shown by solid lines. The sub-lance is then still straight. During the blowing of oxygen the sub-lance is heated on one side in such a way that after the oxygen blowing, it is distorted and assumes the position shown by the broken lines. If the sub-lance is now rotated through 180 degrees about its vertical axis for the next charge of the furnace, the sub-lance as when lowered the position shown in FIG. 1b by solid lines. After further blowing has taken place onto the bath the sub-lance is bent back by the heat so that it is once more straight, as shown in FIG. 1b by broken lines. Between the end of this blowing and the next charge no rotation of the sub-lance is necessary, because the lance is now in the position and shape as in the initial position of FIG. 1a. After the next operation in which the sub-lance is used, however, it will be bent again and it must be rotated once more. If this practice is established, it is therefore sufficient for the sub-lance to be rotated through 180 degrees each time after being used twice.