Field of the invention

The present invention relates to a top charging apparatus for charging material in a blast furnace, provided with an opening/closing device for closing or opening the bottom opening of a material hopper.

Background art

Various devices for closing or opening a seal valve of a material hopper are known from the prior art.

For example, a known device includes a shut-off flap valve or furnace mouth flap valve, which is used to control the charging of a blast furnace with coke and burden material. For the purpose, the device includes a flap plate which, for the purpose of closing or opening the opening of the material hopper arranged above the mouth of a blast furnace, is movable into an open position and into a closed position. In order to move the flap plate into the desired position, a drive mechanism is usually in articulated connection at the flap rim, by which it is ensured that, in the open position, the flap plate leaves the flow opening substantially completely clear. In the process, however, the flap plate is pivoted out relatively far away from the opening, so that the mouth of the blast furnace has to be correspondingly dimensioned in order to avoid a collision of the flap plate with loose material.

A further known device avoids this disadvantage by means of a flap plate in articulated connection with two pivot arms which are mounted so that they can pivot about pivot axes that extend parallel to one another. It is ensured therein that, when the flap plate moves from the closed position to the open position and vice-versa, the rim regions of the flap plate move along oppositely directed arcuate paths. The movement of the flap plate obtained in that manner brings about a movement of the flap plate on a trajectory close to the bottom opening, as a result of which the charging system of the blast furnace can be of more compact construction overall. Guiding the flap plate along the arcuate paths brings about, in the region of the opening, a relative movement between the rim region of the flap plate and the sealing seat provided for the flap plate at the bottom opening. Especially when the sealing region of the flap plate is in contact with the sealing seat of the bottom opening, a relative movement parallel to the plane of the opening is damaging and can result in premature wear of the sealing provisions. Thus, the need is felt to provide a top charging apparatus which allows to overcome the aforesaid drawbacks.

Summary of the invention

It is an object of the present invention to provide a top charging apparatus provided with an opening/closing device for opening or closing the opening of the hopper, said device being extremely compact both in open position and partially open position of the seal valve.

It is another object of the invention to provide an opening/closing device capable of considerably reducing wear at the sealing surfaces.

It is another object of the invention to provide a method for closing/opening a bottom opening of a hopper of said top charging apparatus.

Thus, the present invention achieves the above objects by providing a top charging apparatus for charging material in a blast furnace which comprises a material hopper, having a top opening and a bottom opening defining a longitudinal axis X; and a closing/opening device for closing or opening said bottom opening; wherein said closing/opening device comprises:

- a seal valve;

- at least one handling lever, connected to said seal valve, for moving the seal valve from a closing position to a maximum opening position, or vice versa;

- a first rotation shaft, connected to at least one first part of the handling lever, for actuating said handling lever;

- a second rotation shaft, connected to at least one second part of the handling lever, for actuating said handling lever;

wherein the first rotation shaft and the second rotation shaft have axes of rotation Y, Y’ parallel from one another and perpendicular to a first plane containing the longitudinal axis X;

and wherein the seal valve in said maximum opening position intersects a second plane A, defined by the axes of rotation Y, Y’ of first rotation shaft and second rotation shaft, in an intermediate position between said two axes of rotation Y, Y’. The closing/opening device also comprises:

- a first actuator for actuating said first rotation shaft so as to transmit a linear movement to said at least one handling lever and, thus, to said seal valve; and

- a second actuator for actuating said second rotation shaft so as to transmit a pivoting movement to said at least one handling lever and, thus, to said seal valve. Another aspect of the invention refers to a method for opening the bottom opening of the hopper of said top charging apparatus, the method comprising the following steps:

- providing the seal valve in a closing position in which the bottom opening is closed by said seal valve;

- actuating the handling lever by means of the first rotation shaft for transmitting a linear movement downwards to said seal valve until reaching an intermediate position in which the seal valve is substantially placed parallel to and spaced apart from said bottom opening;

- actuating the handling lever by means of the second rotation shaft for transmitting a pivoting movement to said seal valve until reaching a maximum opening position in which the bottom opening is completely clear.

A further aspect of the invention refers to a method for closing the bottom opening of the hopper of said top charging apparatus, the method comprising the following steps:

- providing the seal valve in said maximum opening position in which the bottom opening is completely clear;

- actuating the handling lever by means of the second rotation shaft for transmitting a pivoting movement to said seal valve until reaching an intermediate position in which the seal valve is substantially placed parallel to and spaced apart from said bottom opening;

- actuating the handling lever by means of the first rotation shaft for transmitting a linear movement upwards to said seal valve until reaching a closing position in which the bottom opening is closed by said seal valve.

Advantageously, according to the invention, the sealing system can comprise a material gate and a seal valve with a sealing disc. The seal valve is used to pressurize the part below and/or above the sealing disc (i.e. the pressure below or above the disc is higher than the pressure above or below the disc). Any equipment that should be pressurized (for example material bunker) or a blast furnace can be placed below the seal valve.

The seal valve arrangement is setup with two particular geometrical constraints:

- the seal valve moves down, when the sealing effect is to be stopped, substantially parallel to the bottom opening. The advantage is that there is minimum wear at the sealing surfaces compared to only rotational movements;

- the seal valve rotates and simultaneously laterally moves up with a movement similar to a spherical movement. The advantage compared to only rotational movement is that the total height (seal valve including disc in open / partly opened position) is minimum.

A further advantage is that dust could fall down from the disc (as compared to horizontal moving discs).

Advantageously the first actuator ensures a linear, substantially vertical, movement of the seal valve, whereas the second actuator ensures a pivoting movement of said seal valve.

In the case of linear actuators, the stroke of the first actuator is advantageously shorter than the stroke of the second actuator. Alternatively, rotating actuators can be used.

The whole mechanism is designed to limit the freedom of movements.

Both actuators are relatively strong actuators, because they are designed to ensure opening at high differential pressure. Sealing force is provided by both said actuators.

Mechanical stops can be provided to stop movements of the components at the correct position. Such mechanical stops can have various designs and can have adjustment possibility.

Both actuators can be electrical, hydraulic or pneumatic.

The dependent claims describe preferred embodiments of the invention.

Brief description of the drawings

Further features and advantages of the invention will be more apparent in light of the detailed description of preferred, but not exclusive, embodiments of a top charging apparatus, disclosed by way of a non-limiting example, with the aid of the accompanying drawings in which:

Figures 1 a and 1 b depict perspective views of an apparatus according to the invention;

Figure 2 depicts a first side view of the apparatus of Figure 1 ;

Figure 3 depicts a second side view of the apparatus of Figure 1 ;

Figure 4 depicts a top view of the apparatus of Figure 1 ;

Figures 5 depicts a cross section view of the apparatus of Figure 1 in an operating position;

Figures 6a and 6b depict side views of parts of the apparatus in two operating positions;

Figures 7a and 7b depict side views of parts of the apparatus in two operating positions.

The same reference numerals in the drawings identify the same elements or components.

Detailed description of preferred embodiments of the invention

With reference to the figures, there is depicted a top charging apparatus according to the invention, indicated by the numeral reference 1 as a whole, suitable for charging material in a blast furnace.

In all its embodiments the top charging apparatus 1 comprises:

- a material hopper 2 having a top opening 3 and a bottom opening 4 defining a longitudinal axis X;

- a closing/opening device for closing or opening said bottom opening 4.

Optionally the upper part of the hopper 2 includes a material inlet zone 20 (Figure 5) between the top opening 3 and a material control valve 21 , placed between said top opening 3 and the bottom opening 4. The material control valve 21 is preferably a gate valve comprising two arcuate parts sliding over one another. Dedicated actuator 30 and linkage 31 are provided to move the arcuate parts of the control valve 21 from a closing position to an opening position (Figures 1 b, 2). Advantageously the closing/opening device for closing or opening the bottom opening 4 comprises:

- a seal valve 5; - at least one handling lever 6, connected to the seal valve 5, for moving the seal valve 5 from a closing position to a maximum opening position, or from the closing position to an intermediate opening position, and vice versa;

- a rotation shaft 14, connected to at least one first part of the handling lever 6, for actuating said handling lever 6;

- a rotation shaft 16, connected to at least one second part of the handling lever 6, for actuating said handling lever 6.

Said intermediate opening position is placed between the closing position and maximum opening position.

The closing/opening device also comprises:

- a first actuator 11 for actuating the first rotation shaft 14 so as to transmit a linear movement to said at least one handling lever 6 and, thus, to said seal valve 5; and

- a second actuator 12 for actuating the second rotation shaft 16 so as to transmit a pivoting movement to said at least one handling lever 6 and, thus, to said seal valve 5.

The rotation shaft 14 and the rotation shaft 16 have a respective axis of rotation Y, Y’. These two axes of rotation Y, Y’ are arranged always parallel from one another and perpendicular to a plane containing the longitudinal axis X. The axes of rotation Y, Y’ lie completely, and thus define, a further plane A.

In a preferred solution the two parallel axes of rotation Y, Y’ are arranged in fixed positions. Said fixed positions are at a same side of the top charging apparatus comprising the maximum opening position of the seal valve 5. Alternatively, at least one of the two rotation shafts 14, 16 and, thus, the respective axis of rotation Y, Y’ are not arranged in a fixed position. For example, at least one of the two rotation shafts 14, 16 can move along a sliding rail or along a linear or curvilinear path defined within slots provided on the end support structures 40, 41 (Figure 2) of said at least one rotation shaft. Also in this latter case, the positions of the two rotation shafts 14, 16 are at a same side of the top charging apparatus comprising the maximum opening position of the seal valve 5.

Preferably the further plane A is inclined by an acute angle higher than 30°, for example in the range of 30-45°, with respect to the plane containing the longitudinal axis X and orthogonal to the sheet of Figure 5. Advantageously the seal valve 5 in the maximum opening position intersects the further plane A, containing the two axes of rotation Y, Y’, in an intermediate position between said two axes of rotation Y, Y’.

Optionally both the rotation shaft 14 and the rotation shaft 16 are placed radially outside of the bottom opening 4, preferably having a diameter lower than 1 ,5 meter.

Preferably the handling lever 6 has a base 7 fixed to the seal valve 5, in particular fixed to the external bottom of the seal valve 5, and two side arms 8 arranged at opposite sides with respect to the hopper 2. The two side arms 8 protrude from the ends of the base 7.

In a variant the closing/opening device is provided with:

- a first linkage, connecting the rotation shaft 14 to a first end 9 of the two side arms 8, for transmitting a linear movement to the seal valve 5;

- and a second linkage, connecting the rotation shaft 16 to a second end 10 of the two side arms 8, for transmitting a pivoting movement to said seal valve 5.

There are provided a first actuator 11 for actuating the rotation shaft 14 so as to transmit a linear movement to the seal valve 5, and a second actuator 12 for actuating the rotation shaft 16 so as to transmit a pivoting movement to said seal valve 5.

The second end 10 of the two side arms 8 is proximal to the base 7, whereas the first end 9 of the two side arms 8 is distal from the base 7.

Preferably the handling lever 6 has an U-shape, the base 7 of the U-shape being fixed to the seal valve 5 and the two side arms 8 having a F-shape or a C-shape.

In a variant the two side arms 8, parallel to each other, are arranged on planes transverse, for example orthogonal, to the plane of the base 7 of the U-shape. In particular, the two side arms 8 are symmetrically arranged with respect to a plane orthogonal to an longitudinal axis defined by the base 7.

Preferably, the base 7 of the U-shape has an inner surface fixed to a lower outer surface of the seal valve 5.

Optionally the seal valve 5 has a sealing disc which is intended for closing or opening the bottom opening 4 of the material hopper 2 and is arranged above the throat of a blast furnace. As a result of opening the sealing disc, loose material, especially ores and burden material, is directed into the throat of the blast furnace through the bottom opening 4 (Figures 5, 7b). In the closed position, the bottom opening 4 is closed off in gas-tight manner by the sealing disc (Figures 1 -3). For the gas-tight closure of the bottom opening 4 there is provided at the rim of the bottom opening 4 a sealing seat (not shown) having sealing elements. On the rim of the sealing disc there is provided a corresponding circumferential sealing surface (not shown), which in the closed position of the seal valve 5 cooperates with the sealing seat to provide sealing.

Preferably the first linkage comprises

- a pair of first levers 15, each first lever 15 being rigidly fixed at a first end thereof to the rotation shaft 14 and hinged at a second end thereof to the first end 9 of a respective side arm 8;

whereby, when the first actuator 1 1 actuates the rotation shaft 14, the first levers 15 rotate so that a linear movement upwards or downwards is transmitted to the handling lever 6 and, thus, to the seal valve 5.

Optionally the rotation angle of rotation shaft 14 and first levers 15 has a maximum value of 10°.

Each first lever 15 is hinged at the second end thereof to the first end 9 of the respective side arm 8 by means of a respective pin 24.

Preferably the second linkage comprises

- a pair of second levers 18, each second lever 18 being rigidly fixed at a first end thereof to the rotation shaft 16;

- and a pair of third levers 19, each third lever 19 being hinged at a first end thereof to a second end of a respective second lever 18 and hinged at a second end thereof to the second end 10 of a respective side arm 8;

whereby, when the second actuator 12 actuates the rotation shaft 16, the second levers 18 rotate so that, by means of the third levers 19, a pivoting movement is transmitted to the handling lever 6 and, thus, to the seal valve 5.

Optionally the rotation angle of rotation shaft 16 and second levers 18 has a maximum value of 90°.

Each third lever 19 is hinged at the first end thereof to the second end of a respective second lever 18 by means of a respective pin 25, and is hinged at the second end thereof to the second end 10 of the respective side arm 8 by means of a respective pin 26.

In a first embodiment the first actuator 1 1 and the second actuator 12 are linear actuators. Advantageously the first actuator 1 1 has a first stroke shorter than a second stroke of the second actuator 12. Preferably the first actuator 1 1 has a first stroke having a maximum value of 100 mm, whereas the second actuator 12 has a second stroke having a maximum value of 700 mm.

Preferably in said first embodiment there are provided:

- a first connecting lever 13 fixed at a first end thereof to the first actuator 1 1 and rigidly fixed at a second end thereof to the rotation shaft 14;

- and a second connecting lever 17 fixed at a first end thereof to the second actuator 12 and at a second end thereof to the rotation shaft 16.

For example, the first actuator 1 1 can have a rod 22 connected to the connecting lever 13 by means a pin 23, whereas the second actuator 12 can have a rod 27 connected to the connecting lever 17 by means a pin 28 (Figures 6a, 6b).

When the rod 22 moves the pin 23 (Figures 6a, 6b), the connecting lever 13 rotates about the axis of the rotation shaft 14 and transmits a rotation to the same rotation shaft 14. The first levers 15 rotate together with the rotation shaft 14 so that a linear movement upwards or downwards is transmitted, by means of pins 24, to the to the first ends 9 of the side arms 8 and, thus, to the handling lever 6 integrally fixed to the seal valve 5.

When the rod 27 moves the pin 28 (Figures 7a, 7b), the connecting lever 17 rotates about the axis of the rotation shaft 16 and transmits a rotation to the same rotation shaft 16. The second levers 18 rotate together with the rotation shaft 16 so that, by means of the third levers 19 and the pins 25, 26, a pivoting movement is transmitted to the second ends 10 of the side arms 8 and, thus, to the handling lever 6 integrally fixed to the seal valve 5.

During this pivoting movement a further rotation of the first levers 15 occurs by means the pins 24. For example, when the rod 27 is retracted, during this pivoting movement a further rotation downwards of the first levers 15 occurs, as visible from Figure 7a to Figure 7b. This advantageously allows a further reduction of the encumbrance of the seal valve 5 in the opening position. Analogously, when the rod 27 is extended, during this pivoting movement a further rotation upwards of the first levers 15 occurs.

In a second embodiment (not shown) the first actuator 1 1 and the second actuator 12 are rotating actuators, for example motors, adapted to transmit the rotation to the rotation shaft 14 and the rotation shaft 16, respectively.

When the motor transmits a rotation to the rotation shaft 14, the first levers 15 rotate together with the rotation shaft 14 so that a linear movement upwards or downwards is transmitted, by means of the pins 24, to the first ends 9 of the side arms 8 and, thus, to the handling lever 6 integrally fixed to the seal valve 5.

When the further motor transmits a rotation to the rotation shaft 16, the second levers 18 rotate together with the rotation shaft 16 so that, by means of the third levers 19 and the pins 25, 26, a pivoting movement is transmitted to the second ends 10 of the side arms 8 and, thus, to the handling lever 6 integrally fixed to the seal valve 5.

Also in this second embodiment, during this pivoting movement a further rotation of the first levers 15 occurs by means the pins 24. For example, when the further motor transmits a rotation to the rotation shaft 16 in a first direction, during this pivoting movement a further rotation downwards of the first levers 15 occurs. Analogously, when the further motor transmits a rotation to the rotation shaft 16 in a second direction, opposite to said first direction, during this pivoting movement a further rotation upwards of the first levers 15 occurs.

In the maximum opening position of the seal valve 5 the inclination angle of the side arms 8 with respect to the longitudinal axis X of the bottom opening 4 is higher than 45°, preferably in the range of 55-90°, for example about 70° (Figure 5). In particular, with reference to Figure 5, this inclination angle is defined between a plane orthogonal to the sheet of Figure 5 and containing the longitudinal axis X and a plane Z containing the axes defined by the two side arms 8, also said plane Z being orthogonal to the sheet of Figure 5.

Therebelow the methods for opening and closing the bottom opening 4 of the hopper 2 of the top charging apparatus are disclosed with reference to Figures from 5 to 7b.

Figure 6a shows the seal valve 5 in the closing position, that means the position in which the bottom opening 4 is closed off in gas-tight manner by the sealing disc of the seal valve 5.

The method for opening the bottom opening 4 comprises the following steps:

- actuating the first linkage by means of the first actuator 1 1 for transmitting a linear movement downwards to the seal valve 5 until reaching an intermediate position (Figure 6b, 7a) in which the seal valve 5 is substantially placed parallel to and spaced apart from the bottom opening (not shown in Figure 6b, 7a);

- actuating the second linkage by means of the second actuator 12 for transmitting a pivoting movement to the seal valve 5 until reaching a maximum side opening position (Figure 7b, 5) in which the bottom opening 4 is completely clear (Figure 5).

Instead, starting from the maximum side opening position of Figures 5, 7b, the method for closing the bottom opening 4 comprises the following steps:

- actuating the second linkage by means of the second actuator 12 for transmitting a pivoting movement to the seal valve 5 until reaching the intermediate position

(Figure 6b, 7a) in which the seal valve 5 is substantially placed parallel to and spaced apart from the bottom opening 4 (not shown in Figure 6b, 7a);

- actuating the first linkage by means of the first actuator 1 1 for transmitting a linear movement upwards to the seal valve 5 until reaching a closing position in which the bottom opening 4 is closed off in gas-tight manner by the sealing disc of the seal valve 5.