Water-cooled Apparatus

Abstract

A water-cooled multitubular lance for introducing oxygen or other materials into the interior of a heated chamber. The lance is designed so that the outermost tubular member is free to expand in an axial direction and carries practically no load. The design is applicable to water-cooled burners, probes and other similar devices.

Description

BACKGROUND OF THE INVENTION

This invention relates to elongated water-cooled tubular devices which are exposed to high temperatures. It relates especially to the construction of water-cooled lances, probes, instruments and burners such as are used in metallurgical operations.

In many metallurgical operations it is a common practice to introduce materials, such as fuels and gases, or instruments, such as thermocouples, into the heated interior of a furnace or converter through an elongated tubular conduit. Since the portion of the conduit in the furnace or converter is exposed to high temperatures for extended periods of time, it is common practice to protect the conduit with a water-cooled jacket. A typical example of such a device is the oxygen lance which is used to introduce gaseous oxygen into a steelmaking converter or furnace. The oxygen lance is normally comprised of a plurality of spaced concentric tubular members some of which are joined at their forward ends by a copper tip or nozzle. The several tubular members not only form a conduit for the gaseous oxygen but also form passages for the circulation of cooling water throughout the lance. The outermost tubular member is subjected to severe temperature and corrosive conditions while the inner tubular members are kept relatively cool and protected by the circulating cooling water. This condition causes the outermost tubular member to expand in length much more than the inner tubular members and unless provision is made for this differential expansion in the construction of the lance, stresses will develop in the lance which will distort the lance and even cause a rupture.

Heretofore, it has been the practice to clamp or otherwise rigidly secure the outermost tubular member of the lance to the lance support mechanism or, in some cases, directly to the wall or roof of the furnace. Because of the differential expansion, the inner tubular members are often fitted with slip joints which will permit the inner tubular members to move freely in longitudinal axial direction. By fitting these slip joints with O-rings or the like, the slip joints can be made fluid tight. With such a lance, the fixed outermost tubular member supports the weight of the cooling water in the lance and the "skull" of metal and slag which sometimes adheres to the exterior of the lance.

The combination of a large structural load and the constant exposure to the extreme temperature and corrosive conditions often causes this outermost tubular member to fail, especially at the connection where it is welded to the copper tip or nozzle. Furthermore, the internal slip joints used in such lances are difficult to maintain due to lack of access. Frequently they do not function and therefore create stresses in the lance severe enough to crack the welded joints or crush the copper tip or nozzle.

The expansion of the outer tubular member in the previously known lance designs causes the lance tip or nozzle and the internal tubular members to move closer to the bath of molten metal in the furnace or converter. Since the spacing of the lance tip relating to the surface of the bath is often critical, this movement may affect the refining process. If the lance, contains instruments this movement may affect their operation.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a design for a water-cooled lance or a similar device in which the outermost tubular member is allowed to move freely in a longitudinal axial direction and also carries practically no load.

It is a further object of this invention to provide a design for a water-cooled lance or similar device in which the weight of the lance, the cooling water and the skull of metal and slag are carried by one or more of the cooled and protected inner tubular members.

It is a still further object of this invention to provide a design for a water-cooled lance or similar device in which the lance tip and the internal tubular members are maintained in a fixed position relative to the surface of a bath of molten metal in a converter or furnace.

It is a still further object of this invention to provide a design for a water-cooled lance or similar device which is easier to construct and maintain than previously known lance designs.

I have discovered the foregoing objects can be attained by placing a fluidtight expansion joint such as a slip joint between the outermost tubular member and the lance support so that the outermost tubular member is free to move in an axial direction as it expands and also carries practically no load.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section of an oxygen lance showing a preferred embodiment of this invention.

FIG. 2 is a cross section of an oxygen lance showing another embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the FIGURES and in particular to FIG. 1, illustrating an oxygen lance of this invention, the lance 1 is comprised of three coaxial concentrically spaced elongated tubular members 2, 3 and 4. The innermost tubular member 2 and the outermost tubular member 4 are connected at their forward ends by a tip or nozzle member 5.

The innermost tubular member 2 is connected at its rearward end to a source of gaseous oxygen under pressure by elbow 6. The tubular member 2 serves as a conduit for the gaseous oxygen before it is finally discharged through the nozzle orifices 7 in the nozzle member 5. The intermediate tubular member 3 divides the space between the innermost tubular member 2 and the outermost tubular member 4 into a pair of passages for the circulation of water or other coolant fluid. The cooling water enters lance 1 through the inlet passage 8 at the rearward end of the lance 1. The water flows downwardly in the passageway formed between the innermost tubular member 2 and the intermediate tubular member 3 until it reaches the nozzle member 5 at which point it is then deflected upwardly in the passageway formed between the intermediate tubular member 3 and the outermost tubular member 4 and finally is discharged through outlet passage 9 at the rearward end of lance 1.

The tubular members 2, 3 and 4 are preferably made of steel. The tip or nozzle member 5 is preferably made of copper or a copper alloy.

As shown in FIG. 1, a steel collar assembly 11 surrounds the rearward end of lance 1 just below the water inlet passage 8 and water outlet passage 9. The collar assembly 11 rests upon or is upon or is otherwise secured to a lance support assembly 12 which not only supports the lance 1 but may also be a carriage to move the lance in and out of the furnace and to hold it in a fixed position relative to the furnace. It is important to note that by securing the inner tubular member 2 to the collar assembly 11, the collar assembly 11 then transmits the entire load of lance 1 to the lance support assembly 12 thereby placing practically no load on the outermost tubular member 4.

As further illustrated by FIG. 1, the rearward end of the outermost tubular member 4 terminates within the collar assembly 11 and is immediately adjacent thereto. Grooves 13 are machined in the outer wall of the rearward end of tubular member 4 to accommodate rubber O-rings 14 which form a fluidtight slip joint between the collar assembly 11 and the outermost tubular member 4.

As a result of this construction of lance 1, the outermost tubular member 4 floats freely and is free to move in an axial direction relative to the collar assembly 11 as it expands while in the heated furnace. The inner tubular member 2 is the load carrying member of the lance 1 and will carry practically the entire load of the lance and the cooling water. The inner tubular member 2 remains fixed.

While the innermost tubular member 2 may be secured to collar assembly 11 by welding, I prefer to use a threaded coupling 15 which screws into the to plate 17 of collar assembly 12 and a lock nut 16 on the rearward end of innermost tubular member 2 in order to permit an easy disassembly of the lance 1 for repair.

FIG. 2 illustrates another embodiment of this invention in which a bellows type of expansion joint 18 joins the rearward end of the outermost tubular member 4 with the collar assembly 11. A flange 19 is welded horizontally to the outer wall of tubular member 4 below the joint 18 to protect the bellows from the heat of the furnace.

With these designs the outermost tubular member is free to move in an axial direction and carries almost no load. Such a construction contributes greatly to a long trouble-free life for such water-cooled devices. Such a construction also insures that the lance tip or nozzle and the inner tubular members remain in a fixed position relative to the surface of the bath of molten metal in the furnace or converter during the course of the heat.

While I have described this invention as applied to an oxygen lance having the oxygen conduit in the center of the lance, it will be apparent that this invention can be applied to oxygen lances having the oxygen pass down an intermediate passageway or to other water-cooled tubular devices such as burners, proves or instruments which use a water jacket as protection against the effects of high temperatures.

Similarly, while I prefer to use the O-ring type of slip joint, other types of expansion joints such as the bellows joint illustrated in FIG. 2 or packing glands could be used to permit the free axial movement of the outermost tubular member 4 without departing from this invention.

Claims

I claim:

1. Apparatus for introducing materials into the heated interior of a chamber comprising:

a. a first tubular member,

b. a second tubular member spaced concentrically within said first tubular member and joined at its forward end with the forward end of said first tubular member,

c. a third tubular member spaced concentrically between said first and second tubular members and forming therewith a pair of passages for a coolant,

d. a collar assembly spaced concentrically outwardly from said tubular members and fixedly secured to the rearward ends of said second and third tubular members, and

e. a fluidtight expansion means sealing the space between the rearward end of said first tubular member and said collar assembly and permitting movement of said first tubular member in an axial direction without movement of the second and third tubular members and said collar assembly surrounding said expansion means and being positioned to substantially reduce the effect of any harmful environment on the expansion means.

2. The apparatus of claim 1 in which the second tubular member forms a conduit for gaseous oxygen.

3. The apparatus of claim 1 in which the expansion means is a slip joint.

4. The apparatus of claim 1 in which the expansion means is a bellows joint.

5. The apparatus of claim 1 in which the expansion means is a packing gland.

6. The apparatus of claim 1 in which the materials are instruments.