Device for inserting a lance into a pressurized container, in particular a blast furnace

A device is presented which equips an opening made in a pressurized container, in particular a blast furnace, for the axial insertion of a lance. This device comprises an axial sealing member, a casing, a first fixed seat, a second axially movable seat and a closure element. The closure element is fitted with a separation spring which produces an axial clearance with respect to the first seat. Closure springs apply the second seat onto the closure element and the closure element onto the first seat. Active opening members, for examples jacks, act against the closure springs. In a preferred embodiment, the device further comprises a spacer element which is identical to the closure element except that it is provided with a through opening for the lance.

BACKGROUND OF THE INVENTION 
This invention relates generally to devices for inserting a lance into a 
pressurized container, in particular a blast furnace. More particularly, 
this invention relates to a device for equipping an opening for the axial 
insertion of a lance into a pressurized container such as a blast furnace 
without loss of leak tightness, either during insertion of the lance or 
total closure of the opening when the lance is entirely withdrawn. 
A device of this kind for inserting a measuring probe into a blast furnace 
is known from U.S. Pat. No. 3,643,508. This device comprises a closure 
member which is fixed with one end on a pipe of a blast furnace and which 
supports an axial sealing member at its free end. The closure member 
comprises a double disc fitted, on one side, with a solid disc and, on the 
other side, with a disc pierced with a through opening for the lance. This 
double disc is pivotable about a pivot axis parallel to the central axis 
of the device and is provided with a slight axial clearance along this 
pivot axis. In order to close the pipe of the blast furnace, the solid 
disc is pivoted into an axial position between a first flange, fixed onto 
the pipe of the blast furnace, and a second flange, supporting the sealing 
member. The two flanges are then axially clamped by screws and nuts in 
order to guarantee leaktightness around the solid disc. In order to pass 
the lance through the pipe, the two flanges are unclamped and the disc 
provided with the through opening for the lance is pivoted into the axial 
position between the two flanges, before reclamping the flanges axially. 
The axial sealing member of this device is fitted with a simple packing 
box. In order to compensate for a slight axial misalignment of the lance, 
the axial sealing member is fixed onto the second flange so as to be 
movable perpendicularly to the central axis of the device. For various 
reasons such as productivity and other reasons it is self-evident that a 
device of this type has not been and is not currently satisfactory. In 
fact, during the exchange of the solid disc and the pierced disc, the 
device provided is even incapable of avoiding leaks from the pressurized 
container. 
An improved embodiment of this device is known from German Patent 
Application DE 15 33 829. The closure member also comprises a double disc 
with a through opening for the lance. This double disc is, however, 
surrounded by a leaktight casing, in which it is pivotable about a pivot 
axis parallel to the central axis of the device and has a slight axial 
clearance on this pivot axis. In order to improve the leaktightness around 
the solid disc, and the pierced disc respectively, the device is fitted 
with an annular hydraulic piston which is equipped with sealing gaskets. 
When this annular hydraulic piston is actuated, these sealing gaskets are 
applied onto the respective disc which is in front of them. This disc in 
turn bears on sealing gaskets integrated in an axially opposite surface. A 
disadvantage of this solution is that, during the pivoting of the double 
disc, the sealing gaskets bearing on the double disc are highly stressed. 
In order to increase the life of the sealing gaskets the aforementioned 
patent application provided these sealing gaskets with a special 
lubricating system. It will also be noted that, in the event of sealing 
problems with the annular hydraulic piston, the leaktightness of the 
device provided in this German Patent can no longer be reestablished. 
It will be appreciated that there is a need to provide a device equipping 
an opening made in a pressurized container, in particular a blast furnace, 
for the axial insertion of a lance therein, which ensures more reliable 
leaktightness than the devices of the prior art. 
SUMMARY OF THE INVENTION 
The above-discussed and other problems and deficiencies of the prior art 
are overcome or alleviated by the device for inserting a lance into a 
pressurized container, in particular a blast furnace of the present 
invention. In accordance with the present invention, a device for 
equipping an opening for the axial insertion of a lance into a pressurized 
container such as a blast furnaces comprises: 
(1) a sealing member designed to ensure axial leaktightness around the 
lance when the lance is inserted therein, 
(2) a leaktight casing situated between the pressurized container and the 
aforementioned sealing member and provided with first and second through 
openings for the lance, these through openings being axially spaced, 
(3) a first seat situated inside the leaktight casing and connected in a 
leaktight manner to the first through opening for the lance, 
(4) a second seat situated inside the leaktight casing and connected in a 
leaktight manner to the second through opening for the lance, the second 
seat being arranged axially opposite the first seat and being axially 
movable with respect to the first seat, 
(5) a closure element mounted in the leaktight casing so as to be movable, 
by a first movement, between an axial position in which it is axially 
aligned between the first and the second seat and a lateral position in 
which it is situated outside of the axial alignment of the two seats and, 
by a second movement, axially between the first and the second seat, 
(6) at least one separation spring which is connected to the closure 
element so as to produce an axial clearance between the first seat and the 
closure element when the closure element is in its axial position, 
(7) at least one closure spring which is connected to the second seat so as 
to move it towards the first seat and which is dimensioned so that the 
second seat can push the closure element, against the action of the 
separation spring or springs, against the first seat when this closure 
element is in its axial position, and 
(8) at least one active opening control member which is connected to the 
second seat and which is dimensioned so as to be able to move the second 
seat, against the action of the closure spring or springs, in the 
direction opposite the first seat into a retracted position in which the 
second seat defines an axial clearance with respect to the closure element 
when the closure element is in its axial position. 
An important advantage of the device in accordance with the present 
invention is that it is a "fail safe" device. In fact, the force which 
applies the second seat onto the closure element and the closure element 
onto the first seat, thus ensuring leaktightness, is produced by the 
closure spring, that is to say a passive element, which requires no 
additional energy. The active opening control member, for example a linear 
or a rotary motor, which requires an additional (hydraulic or electrical) 
energy supply, is only involved in the case of intentional elimination of 
leaktightness of the container with respect to the leaktight casing; that 
is to say during the axial separation of the second seat with respect to 
the first seat. 
A further advantage of the device provided in accordance with the present 
invention is that the first seat defines a first axial clearance with 
respect to the closure element, and the second seat defines a second axial 
clearance with respect to the closure element, before movement of the 
closure element from its axial position into its lateral position and vice 
versa. It will be appreciated that this first clearance and this second 
clearance ensure that during the movement of the closure element, that the 
contact surfaces are not stressed. A lubrication system for sealing 
elements or surfaces is therefore superfluous. Both clearances are 
established automatically, by simple recoil of the second seat into its 
retracted position. 
To insert the lance into the pressurized container, after having inserted 
the lance with its front end into the sealing member and after having 
moved the second seat into its retracted position, the closure element is 
moved into its lateral position, which frees the axial passage for the 
lance through the device. Now, in this position, the leaktight casing is 
exposed to the pressure and the atmosphere of the pressurized container. 
If it is desired to reestablish the leaktightness of the leaktight casing 
with respect to the pressurized container, it is now possible to 
deactivate the opening control member, which will cause the second seat to 
be applied axially onto the first seat, under the action of the closure 
spring or springs. In order to guarantee the leaktightness between the two 
seats, it is sufficient, for example, to provide an elastic sealing 
element on at least one of the two seats. With the aim of simplifying the 
seats, and above all with the aim of reducing the axial travel of the 
second seat, it is preferable to fit the device with a spacer element 
which is identical to the closure element except the fact that this 
closure element is provided with a through opening for the lance. This 
spacer element is mounted in the leaktight casing in the same manner as 
the aforementioned closure element. In other words, it is movable, by a 
first movement, between a lateral position in which it is situated outside 
of the axial alignment of the two seats (when the closure element is in 
its axial position), and an axial position in which it is axially aligned 
between the first and the second seat (when the closure element is in its 
lateral position), and, by a second movement, axially between the first 
and the second seat. At least one separation spring is preferably 
connected to the spacer element so as to produce an axial clearance 
between the first seat and the spacer element, when the spacer element is 
in its axial position. 
The closure element and the spacer element are advantageously fitted with 
sealing gaskets which are mounted so as to be opposite corresponding 
sealing surfaces of the first and second seats, when the closure element 
and the spacer element respectively are situated in their axial position. 
In order to fully understand the advantage of not having sealing gaskets 
on the seats, but of having them on the closure and spacer elements, it is 
important to note that the closure element and the spacer element are 
replaceable, in their lateral position, without breaking the leaktightness 
with respect to the pressurized container. In order to have access to the 
sealing surfaces of the first and second seats, it is, however, necessary 
to break the leaktightness with respect to the pressurized container. 
In a preferred embodiment, the closure element and, optionally, the spacer 
element are pivotable about a pivot axis which cuts the axis along which 
the lance is inserted. These elements are then plates axially bounded by 
surfaces of revolution, the axis of revolution of which corresponds to the 
aforementioned pivot axis. These surfaces of revolution face complementary 
sealing surfaces of the first seat and of the second seat when the 
respective plate is in its axial position between the two seats. This is 
an embodiment which makes it possible to have a leaktight casing with a 
smaller size than a device of the type provided in DE 15 33 829, which is 
fitted with a double disc that can be pivoted above an axis parallel to 
the axis along which the lance is inserted. 
In another preferred embodiment, for a lance having a cross-section which 
is higher than it is wide, the pivot axis is parallel to the height of the 
aforementioned cross-section, and the surfaces of revolution are 
cylindrical surfaces. This is a solution which makes it possible to have 
minimal size of the leaktight casing. 
In all the embodiments of the device in accordance with the present 
invention, there is most often the advantage of choosing an active opening 
control member which comprises one or more hydraulic jacks in which the 
closure springs are integrated. This results in a relatively compact and 
simple device. 
If the hydraulic jacks are then mounted outside the leaktight casing and 
connected to the second seat by control rods which penetrate into the 
leaktight casing, neither the jacks nor the springs will be exposed to the 
atmosphere prevailing in the leaktight casing. 
It is possible to provide mechanical means (for example a screw, a hook, 
etc.) for temporarily blocking the second seat in a sealing position. In 
this position the second seat sealably bears either on the closure element 
which then itself bears sealably on the first seat or on the said spacer 
element which then itself bears sealably on the first seat. In this way, 
it is possible to interchange the closure spring or springs without 
breaking the leaktightness with respect to the pressurized container. 
In a preferred embodiment, the device comprises at least one axial stop, 
for the second seat. This axial stop is preferably adjustable in order to 
axially block the second seat both in its retracted position and in its 
sealing position. 
Preferably, the device in accordance with the present invention comprises 
an axial compensator which is connected between the second seat and the 
second axial through opening for the lance. This approach eliminates the 
need to use sealing gaskets of the "O-ring" type or packing boxes, which 
might possibly constitute unnecessary weak points. 
One simple way of supporting the closure element and/or the spacer element 
is to provide telescopic support arms. The spacer springs are then 
advantageously integrated in these telescopic arms. 
In a preferred embodiment, the device in accordance with the present 
invention comprises the following elements: 
(1) the first seat is supported inside the leaktight casing by a passage 
sleeve for the lance, 
(2) each of the two telescopic arms of the closure element is fitted with a 
pivot pin, and 
(3) housings for the pivot pins are provided between the leaktight casing 
and the sleeve, so as to define a pivot axis for the closure element 
and/or spacer element, which cuts the central axis of the device provided. 
It will be appreciated that a preferred embodiment of the sealing member is 
also provided. This sealing member comprises: 
(1) a casing subdivided into chambers separated axially by ribs, and 
(2) rings provided with a passage cross-section which matches the 
cross-section of the lance, each of the rings being mounted in one of the 
chambers of the casing so as to be able to slide in the casing 
perpendicularly with respect to the central axis of the sealing member. 
This preferred embodiment not only allows axial misalignment of the lance, 
but also improves the leaktightness when the lance is inserted obliquely 
through the device of the present invention. Furthermore, the sealing 
elements do not undergo exaggerated local compressive forces during 
oblique insertion of the lance into the sealing member.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring first to FIG. 1, the device for inserting a lance into a 
pressurized container, in particular a blast furnace, of the present 
invention is shown in section through the central axis by the entire FIG. 
1. 
FIG. 1 shows a section through a wall 10 of a pressurized container 8, for 
example a blast furnace, at the level of an opening 12 which passes 
through this wall 10. FIG. 2 shows a similar section, making an angle of 
90.degree. with the section plane of FIG. 1. The wall 10, represented by 
way of illustration, comprises an inner refractory lining 14 and an outer 
shielding 16. At the level of the opening 12, the shielding 16 forms a 
sleeve 18 which is fitted with a flange 20. The central axis of this 
flange 20 defines the central axis 12' of the opening 12 in the wall 10. 
The reference 22 identifies a lance which is to be inserted along the axis 
12' through the opening 12 in the container 8. It will be assumed that 
this is, for example, a probe for making temperature measurements and/or 
for taking samples of gas from the charge of a blast furnace. Such a 
probe, which is inserted almost horizontally into the charge, may have a 
length of 8 meters or more. In order to improve its strength, it is 
generally of oval cross-section, that is to say that its height is larger 
than its width, as can be seen by comparing FIG. 1, which represents a 
section through a horizontal plane, with FIG. 2, which represents a 
section through a vertical plane. 
The reference 24 refers overall to a device which equips the opening 12 and 
which allows insertion of the lance or probe 22 through this opening 12 
into the container or blast furnace 8. The device 24 which is represented 
in the FIGURES comprises, for this purpose, from the outside inwards: a 
sealing member 26, a closure member 28 and a support member 30. Before 
describing these three members in detail, their function will be described 
in brief. The sealing member ensures the axial leaktightness around the 
lance 22. It will be noted that, as long as the lance 22 is engaged in the 
sealing member 26, it provides leaktight closure of the opening 12. The 
closure member 28 makes it possible to close the opening 12 in a leaktight 
manner when the lance 22 is to be entirely withdrawn from the sealing 
member 26. The support member 30 constitutes a front support for the lance 
22. This support has the purpose of reducing the overhanging length of the 
lance 22 inside the container 8. 
The sealing member 26 comprises a casing 32 which is subdivided into 
several chambers 34. These chambers 34 are separated axially by ribs 36 
which define, with respect to the cross-section of the lance 22, a large 
clearance referred to, for example, by the reference 37. The reference 38 
labels rings whose free cross-section matches the cross-section of the 
lance 22. Each of these rings 38 is mounted in one of the chambers 34 so 
as to be movable perpendicularly to the central axis 12' of the sealing 
member 26. This possibility of movement of the rings 38 in their 
respective chamber 34 of the casing 32 allows the rings 38 to adapt to an 
oblique position of the lance 22 in the sealing member 26. In other words, 
the rings 38 can be freely centered on the lance 22 when it is inserted 
obliquely through the sealing member 26. 
It will be noted that the rings 38 constitute either themselves sealing 
members, or supports for packings or sealing gaskets which bear on the 
lance 22. It will also be noted that at least one of the rings 38 
advantageously constitutes a support for a sealing gasket which can be 
inflated by a liquid or a gas. This inflatable gasket then makes it 
possible to make a larger and variable clearance between the lance and the 
respective ring leaktight. 
FIG. 2A represents a detail of a first embodiment of a ring 38 in its 
chamber 34. It is seen that it is fitted with two sealing gaskets 200 with 
which it bears on the lance 22. Lateral sealing gaskets 202 provide, if 
necessary, leaktightness between the ring 38 and the radial ribs 36 
defining the chamber 34. 
FIG. 2B represents an alternative embodiment of the ring 38 in its chamber 
34. It comprises an inflatable seal 204 installed in a cavity 206 of the 
ring 38. In the deflated position, this inflatable seal 204 is set back in 
its cavity 206, which makes it possible to move the lance 22 without 
damaging or wearing the inflatable seal 204. In the inflated position, the 
inflatable seal 204 of FIG. 2B is capable of compensating for much larger 
radial clearances than the two sealing gaskets 200 in FIG. 2A. As in FIG. 
2A, the ring 38 advantageously bears with two sealing gaskets 208, which 
flank the cavity 206, on the lance 22. The inflatable seal 204 is 
advantageously pressurized by pressurizing the chamber 34. Openings 210 in 
the ring 38 connect the chamber 34 with the cavity 206. It should be noted 
that the inflatable seal 204 may be inflated by a liquid or a gas under 
pressure. 
The closure member 28 comprises a leaktight casing 40 which is fitted with 
a first end plate 42 and with a second end plate 44 which are axially 
separated from each other. On the end plate 44 side, the leaktight casing 
40 is fixed in a leaktight manner onto the flange 20 of the container 8. 
On the end plate 42 side, it supports the sealing member 26 in a leaktight 
manner. 
The plates 42 and 44 comprise through openings 46 and 48, coaxial with the 
central axis 12' for passage of the lance 22. The opening 46 in the plate 
42 is fitted with a sleeve 50, for the passage of the lance 22, which 
extends axially towards the opening 48 in the plate 44. At a certain 
distance from the plate 44, the sleeve 50 ends in a first seat 52 which 
surrounds the mouth of the sleeve 50 in the leaktight casing 40. A second 
seat 54 axially faces the first seat 52. This second seat 54 is connected 
in a leaktight manner to the first plate 44. In addition, it is axially 
movable in the casing 40. In the device shown in the attached FIGURES, the 
connection of the second seat 54 to the plate 44 is accomplished by using 
an axial compensator 56. The second seat 54 might, however, also be 
engaged on or in a guide sleeve supported by the plate 44, on condition 
that suitable sealing elements are provided between the second seat 54 and 
this guide sleeve, which sealing elements tolerate an axial movement 
between the second seat 54 and the guide sleeve without being worn too 
quickly. 
The second seat 54 is preferably fitted with a kind of stirrup piece 58 to 
which control rods 60 are connected which extend, parallel to the axis 
12', through the plate 42 outside the leaktight casing 40. These control 
rods 60 are used for moving the second seat 54 axially. 
The references 62 and 64 label means for driving the rods 60, for example 
jacks fitted with closure springs 66. It is important to note that the 
spring elements 66, which are preferably integrated in the jacks 62 and 
64, are designed to exert on the second seat 54 a force in the direction 
of the first seat 52. Pressurizing the jacks 62, 64 moves the second seat 
54 axially away from the first seat 52, against the action of the springs 
66. Axial stops 68 limit the axial movement of the second seat 54 in the 
direction of the plate 44, and define a limit retracted position of the 
plate 44. These axial stops 68 might however also be replaced by stops 
which are integrated in the jacks 62 and 64. 
The reference 70 labels the closure element proper of the closure member 
28. It is, for example, a cylindrical plate which can be pivoted about an 
axis 72 which intersects the axis 12'. In FIG. 2, this axis cuts the axis 
12', for example at a right angle. In order to decrease the axial size of 
the closure member 28, the pivotable closure plate 70 is advantageously 
axially defined by a first surface 74 and a second surface 76 which are 
surfaces of revolution having the pivot axis 72 for the plate 70 as the 
axis of revolution. In particular, these surfaces 74 and 76 may be 
cylindrical surfaces coaxial with the axis 72, as represented in the 
FIGURES. They may, however, also consist of spherical or conical surfaces, 
or even be surfaces of revolution generated by the rotation of any 
generatrix curve around the axis 72. What is important is that the seats 
52 and 54 are axially defined by sealing surfaces complementary to the 
first surface 74 and the second surface 76 of the closure element 70 
respectively. In the device represented in the FIGURES, the seats 52 and 
54 are then axially defined by cylindrical surfaces 74' and 76' which are 
complementary to the cylindrical surfaces 74 and 76 of the cylindrical 
plate 70. 
It will be noted that the suspension of the cylindrical plate 70 in the 
leaktight casing 40 has to be designed so that it can be moved by the 
second seat 54 in the direction of the first seat 52 against the action of 
an elastic force, when it is located axially between the first seat 52 and 
the second seat 54. In the device represented in the FIGURES, the 
suspension of the cylindrical plate 70 in the leaktight casing 40 is, for 
this purpose, produced using two telescopic arms 80 which are situated on 
either side of the sleeve 50. Springs 78 are integrated in the telescopic 
arms 80 so as to move the closure element 70 away from the fixed seat 52. 
A stop 81, integrated in the telescopic arm 80, defines the maximal 
extension of these telescopic arms 80, that is to say the travel of the 
closure element 70 under the effect of the spacer springs 78. 
The arms 80 are each fitted with a pivot pin 82, which is, for example, 
housed with one end in a first bearing 84 which is supported by the sleeve 
50, and with a second end in a second bearing 86 which is supported by the 
casing 40. One of the two pivot pins 82 is then connected to a drive 
member 88 which is diagrammatically represented in FIG. 2. It will be 
noted that this drive member 88 is designed to be able to pivot the 
closure element 70 through an angle of approximately 90.degree. about the 
axis 72. 
The pivot pins 82 support not only the closure element 70 but also a spacer 
element 90 which is itself also pivotable about the axis 72. This spacer 
element 90 is exactly identical to the closure element 70 apart from the 
fact that its cylindrical plate is provided with a through opening 92 for 
the lance 22. It is mounted on the pivot pins 82 so as to be directly next 
to the closure element 70. Like the closure element 70, the spacer element 
90 is itself also fitted with telescopic arms 94 which are equipped with 
springs 96, so as to move it axially away from the seat 52. Instead of 
providing telescopic arms 80 and 94 with springs 78, 96 for the closure 
element 70 and the spacer element 90, it might also be possible to provide 
support arms of fixed length and to give the pivot pins 82 a possibility 
of axial movement against a spring. 
From the point of view of leaktightness, it will be noted that the closure 
element 70, as well as the spacer element 90, are fitted on both sides 
with sealing gaskets. These sealing gaskets are mounted on the closure 
element 70 and the spacer element 90 so as to be situated facing the 
sealing surface 74' of the first seat 52 and the sealing surface 76' of 
the second seat 54 respectively, when these elements 70 and 90 are 
situated in axial alignment between the two seats 52 and 54. 
The support member 30 is described with the aid of FIGS. 1 and 2. It 
comprises a sleeve 110, which extends overhanging towards the inside of 
the container 8. The sleeve 110, which is preferably integral with the 
plate 44, is advantageously provided with a cooling circuit 112 if the 
conditions inside the pressurized container 8 so require, as is, for 
example, the case on a shaft furnace or a blast furnace. With its free 
end, the sleeve 110 supports an internal support 114 for the lance 22. 
This is a bearing on which the lance 22 can bear with its lower periphery 
when it is inserted through a side opening of the wall 10. Its purpose is 
then to decrease the overhanging length of the lance 22 inside the 
container 8. If the lance 22 is, on the other hand, inserted vertically 
into the container 8, or, if it only has a small overhanging length inside 
the container 8, it is naturally possible to do without this support 
member 30. It will then be noted that the presence of the support member 
30 is justified only in particular applications, which involve reducing 
the maximum bending moment and shearing force to which the lance 22 is 
subjected when it is overhanging in the container 8. Such is, for example, 
the case for the temperature and gas-sampling probes for blast furnaces. 
The operation of the device provided by the present invention will be 
described with the aid of FIGS. 3 to 6. In FIG. 3, the lance 22 is 
inserted with its front end into the sealing member 26. The closure member 
is in the closed position, that is to say the jacks 62 and 64 are not 
pressurized, and the springs 66 exert a force on the second seat 54 in the 
direction of the first seat 52. The second seat 54 bears, by virtue of the 
action of the springs 66, with its sealing surface on the closure element 
70 which is arranged axially between the first and the second seat 52 and 
54 and applies the closure element 70, against the action of the spacer 
spring 78, on the sealing surface of the first seat 52. In other words, 
the closure member 28 is held closed by the action of the closure springs 
66 which hold the second seat 54, the closure element 70 and the first 
seat 52 axially in leaktight bearing on one another. 
In order to allow insertion of the lance 22 into the container 8, the jacks 
62 and 64 are first of all pressurized. These jacks 62 and 64 then exert a 
pressure on the second seat 54 which opposes the action of the spring 66 
and moves the seat axially away from the first seat 52. By virtue of the 
spacer spring 78, the closure element 70 follows the recoil movement of 
the second seat 54, until it is stopped by the stop 81. At this moment 
there is a first axial clearance between the sealing surface of the first 
seat 52 and the sealing gaskets incorporated in the first surface 74 of 
the closure element 70. The second seat 54 continues its recoil movement 
in the direction of the second end plate 44, until it bears, for example 
via the stirrup piece 58, on the axial stops 68. In this retracted 
position, there is a second axial clearance between the sealing gaskets 
incorporated in the second surface 76 of the closure element 70 and the 
sealing surface of the second seat 54. By virtue of this first and this 
second axial clearance, the closure element 70 can be pivoted about the 
axis 72 by the drive member 88 (cf FIG. 2) into a lateral position with 
respect to the two seats 52 and 54 without risking damage to the sealing 
gaskets. 
It will be noted that, in FIGS. 4 and 5, the leaktight casing 40 is in 
direct communication with the container 8. The leaktightness of the 
leaktight casing 40 with respect to the surroundings is guaranteed by the 
end of the lance 22 which is engaged in the sealing member 26. In order to 
limit the exposure of the casing 40 to the atmosphere prevailing in the 
container 8, and in order to limit, for example in the case of a blast 
furnace, the penetration of dust into the casing 40, it is most often 
advantageous to isolate the leaktight casing 40 with respect to the 
container 8 when the closure element 70 is in the lateral position with 
respect to the two seats 52 and 54. For this purpose, it would be possible 
simply to cut the supply pressure of the jacks 62 and 64, in order to 
apply the seat 54 directly against the seat 52 by means of the closure 
springs 66. This approach would, however, make it necessary to design the 
sealing surface 74' of the first seat 52 and 76' of the second seat 54, 
respectively, so as to ensure not only leaktightness when they are applied 
against the surfaces 76 and 74 of the closure element 70, but also when 
they are applied on one another. In order to avoid this problem, and in 
order at the same time to limit an excessively large axial movement of the 
second seat 54, the spacer element 90 has been provided. This spacer 
element 90 is automatically axially positioned, after pivoting of the 
closure element 70 into its lateral position, between the first seat 52 
and the second seat 54 (cf. FIG. 5). 
After cutting the supply of the jacks 62 and 64, the closure springs 66 
hold the second seat 54, the spacer element 90 and the first seat 52 
axially bearing in a leaktight manner on one another. It will be noted 
that, in this situation which is represented in FIG. 6, the sealing 
gaskets of the spacer element 90 are applied exactly in the same manner on 
the sealing surfaces 74' and 76' of the first and second seats 52 and 54 
respectively, as the sealing gaskets of the closure element 70 are in the 
situation represented in FIG. 3. In addition, the second seat 54 occupies 
exactly the same position in FIG. 6 as in FIG. 3. In the situation 
represented in FIG. 6, the leaktight casing 40 is now passed through by a 
leaktight channel for the lance which is formed, in the direction of 
insertion of the lance, by the sleeve 50, the first seat 52, the spacer 
element 90, the second seat 54 and the axial compensator 56. 
Other advantages and features of the closure member in FIGS. 1 to 6 will be 
described with the aid of FIG. 7. In this FIGURE, the closure member 28 is 
in the same position as that represented in FIG. 6. It will be noted that 
the leaktight casing 40 is provided with two juxtaposed access openings 
100 and 102 which give access to the inside of the leaktight casing 40, or 
more precisely to the two lateral positions, in which the closure element 
70 and the spacer element 90 are respectively situated when they are 
pivoted out of axial alignment with the two seats 52 and 54. 
In FIG. 7, the access opening 102, which gives access to the closure 
element 70, is open, while the access opening 100 is closed. It will be 
noted that it is thus easily possible to remove the closure element 70, 
which is, for example, fixed by screws onto the arm 80, while at the same 
time retaining leaktightness with respect to the container 8. In this 
position, it is also possible to replace the separation springs 78 in the 
telescopic arms 80. If it is desired to remove the spacer element 90, the 
closure member 28 is placed in the position represented in FIG. 3 and the 
access opening 100 is open. It will be appreciated that all the sealing 
gaskets are supported either by the closure element 70 or by the spacer 
element 90, which are both easily removable. In order to be able to 
replace these sealing gaskets, it is then sufficient to remove these two 
elements 70 and 90 in succession and to carry out the replacement of the 
sealing gaskets in the workshop. The advantage is that this replacement of 
the seals can be carried out when the container 8 is under pressure. The 
replacement of the seals of the closure element 70 can even be carried out 
without the need to withdraw the lance 22 from the container 8. 
Another feature of the device represented in the FIGURES is that it is 
possible to remove the jacks 62 and 64 containing the closure springs 66, 
without thereby losing leaktightness with respect to the container 8. For 
this purpose, the stops 68 are axially adjustable so as to make it 
possible to block the second seat 54 and the spacer element 90, and the 
closure element 70 respectively, axially against the first seat 52. In 
FIG. 7, the stops 68 comprise, for example, a sleeve 104 with an internal 
screw thread fixed onto the plate 44, into which a threaded rod 106 is 
screwed. The latter is designed so as to be able to bear on the stirrup 
piece 58 when the second support 54 presses the spacer element 90 and the 
closure element 70 respectively onto the first seat 52. In this position, 
the stops 68 replace the closure springs 66 and it is possible to remove 
the jacks 62 and/or 64 containing the closure springs 66 without any 
problems. After remounting the jacks 62 and/or 64, the threaded rod 106 is 
driven into the sleeve 104 in order to define the maximum travel of the 
second seat 54 in the direction of the second plate 44. It will also be 
appreciated that, in the device represented in the FIGURES, the jacks 62 
and 64 and the closure springs 66 are arranged outside the leaktight 
casing 40. In this way, these essential elements are never exposed to the 
atmosphere prevailing in the container 8. 
While preferred embodiments have been shown and described, various 
modifications and substitutions may be made thereto, without departing 
from the spirit and scope of the invention. Accordingly, it is to be 
understood that the present invention has been described by way of 
illustrations and not limitations.