Patent Application
20180266768
The present disclosure generally relates to a sealing valve arrangement for a shaft furnace charging installation and more specifically to an upper or lower sealing valve arrangement for preventing furnace gas loss in a blast furnace charging installation.
Shaft furnace charging installations of the BELL LESS TOP® type have found widespread use in industry during the last decades. An early example of such an installation is disclosed e.g. in U.S. Pat. No. 4,071,166. This installation minimizes escape of blast furnace gas from the furnace throat by operating one or more intermediate charge material storage hoppers in the manner of a sluice or airlock. To this effect, each hopper has an upper sealing valve and a lower sealing valve for sealing closure of the hopper inlet and outlet respectively. During filling of the hopper, the upper sealing valve is open whilst the lower sealing valve is closed. When material is charged from the hopper into the furnace, the lower sealing valve is open whilst the upper sealing valve is closed. U.S. Pat. No. 4,071,166 discloses a commonly used sealing valve arrangement with a flap-type valve, in which the shutter is tiltable about a single shaft. The axis of this shaft is arranged approximately in the plane of the valve seat. Since the shutter has to be completely removed from the material flow path in the open position, the arrangement according to U.S. Pat. No. 4,071,166 requires considerable space in the vertical direction, both inside the lower sealing valve housing and inside each intermediate storage hopper (see e.g.
In order to reduce “lost” vertical constructional space, improved so-called dual-motion shutter-actuating devices have been proposed. U.S. Pat. No. 4,514,129 proposes such a dual-motion shutter-actuating device. This device is configured to tilt the valve about a first axis and to separately pivot the shutter together with its mounting arm about a second axis that is perpendicular to the first axis. This dual-motion shutter-actuating device allows moving the shutter into a higher parking position located laterally of and partially above the seat. The valve arrangement according to U.S. Pat. No. 4,514,129 thereby considerably reduces the required constructional height. U.S. Pat. No. 4,755,095 discloses a similar shutter-actuating device in an upper sealing valve arrangement, i.e. for sealing the inlet of the hopper. A drawback of these types of shutter-actuating devices however lies in that they have a number of articulated parts prone to wear and exposed to harsh conditions.
WO 2010/015721 A1 describes a further dual-motion lower sealing valve assembly for a shaft furnace charging installation comprising a lower sealing valve housing with a valve seat. The shutter is adapted to cooperate with the valve seat and operatively connected to a valve actuation mechanism, which can be supported by the top plate of the lower sealing valve housing, for moving the shutter into and out of sealing contact with the valve seat. In particular, the valve actuation mechanism comprises a turn-slide cylindrical joint supporting the shutter. The cylindrical joint has a substantially vertical joint axis according to which the joint allows translating the shutter up and down, e.g. in vertical direction, and in a plane perpendicular to which the joint allows swiveling the shutter, typically in a substantially horizontal plane. The turn-slide cylindrical joint comprises: a shaft, acting as output shaft of the joint, an intermediate hollow sleeve, in which the shaft is mounted, and an outer shell, supporting the sleeve and forming the fixed frame of the joint. The shaft is axially fixed and rotatable about the joint axis in the hollow sleeve. The sleeve is axially slidable along the joint axis in the outer shell that is fixed to the housing. The mechanism further comprises a first hydraulic cylinder for axial translation (sliding) and a second hydraulic cylinder for rotation (turning). The first cylinder has one side connected to the outer shell and the other side connected to the hollow sleeve, for axially translating the shaft with the sleeve along the joint axis relative to the shell. The second hydraulic cylinder has one side hinged to the sleeve and the other side hinged to the shaft in order to rotate the shaft relative to the intermediate sleeve about the joint axis. However, again, due to the fact that the translational movement is done in a dusty environment, the life time of the mechanism is shortened due to the fact that during actuation, dust may enter the seals and damage the sealing surfaces. A further disadvantage of this solution is the fact that particles falling on the shutter cannot fall down.
WO 2011/000966 A1 discloses a still further dual-motion shutter-actuating device is of the type configured to confer to the shutter a superposition of two rotations about substantially parallel and offset axes, i.e. offset axes having a relative orientation closer to parallel than to perpendicular. To this effect, the device comprises a primary tilting arm supported on a first tilting shaft, which is equipped with bearings to rotatably support the primary tilting arm on a stationary structure, typically either a lower sealing valve housing or on the shell of an intermediate storage hopper, in rotatable manner about an immobile first axis; a secondary tilting arm that carries the shutter and is supported on a second tilting shaft, which is equipped with bearings that rotatably support the secondary tilting arm on the primary tilting arm, in rotatable manner about a second axis that is essentially parallel to the first axis and moves with the secondary tilting arm; and a mechanism configured to impart rotation about the second axis to the secondary tilting arm at the same time as the primary tilting arm rotates about the first axis. In this solution, the first tilting shaft is configured as hollow sleeve shaft and the shutter-actuating device comprises a reference rod that extends through the first tilting shaft. This reference rod has a distal end portion to be connected to a stationary structure and a proximal end portion with a reference member, the mechanism having a driven side that is in engagement with the reference member. The main disadvantage of this solution is the number of movable parts, which render the device more costly in terms of manufacturing and assembling. Finally, the mechanism is to be operated inside a dusty environment although covered against dust.
In view of the above, the present disclosure provides a sealing valve arrangement with a shutter-actuating device that combines reduced construction height with reduced number of movable parts, preferably a reduced number of movable parts directly exposed to harsh conditions.
The present disclosure proposes in a first aspect a sealing valve arrangement, especially for lower or upper sealing valve arrangements for a charging installation of a shaft furnace, such as a blast furnace. The sealing valve arrangement comprises a shutter arranged for cooperating with a valve seat of a sealing valve and an integrated dual-motion shutter-actuating device for moving said shutter between a sealed closed position in sealing contact with the valve seat and an open position remote from the valve seat, preferably located laterally thereof. In said open position, the passage or material flow path through the sealing valve is entirely cleared by the shutter.
The integrated dual-motion shutter-actuating device comprises:
According to the present disclosure, said integrated dual-motion shutter-actuating device further comprises a stationary outer cylindrical sleeve. The primary motion assembly comprises an inner eccentric sleeve shaft (first eccentric sleeve shaft) rotationally mounted within said outer cylindrical sleeve and a primary motion actuator configured to impart angular rotation to said inner eccentric sleeve shaft, the primary motion being a function of the eccentricity and angular rotation of the inner eccentric sleeve shaft. Furthermore, said tilting shaft of said secondary motion assembly is rotationally mounted within said inner eccentric sleeve shaft of said primary motion assembly, the secondary motion being a function of the angular rotation of the tilting shaft.
The main advantage of the disclosure is that all parts responsible for both primary and secondary motions of the shutter, i.e. the unclamping from the valve seat and the tilting away of the shutter in a parking position are done with an assembly having only very few and constructionally simple parts, which are moreover easily serviceable and protectable against dust and temperature.
As indicated above, the primary motion, in particular the distance and path by which the shutter is moved during this primary motion, is a function of the eccentricity and angular rotation of the inner eccentric sleeve shaft. An eccentric sleeve shaft in the context of the disclosure generally resembles a conventional sleeve shaft, i.e. a shaft with a central longitudinal (coaxial) bore to hold e.g. a further shaft, except that the center of the bore is not central or coaxial, but rather shifted or offset (off-center) by a distance with respect to central axis of the sleeve shaft. This offset distance, also termed eccentricity, will determine the maximum extent of the primary movement, i.e. the maximum distance the shutter may be moved away from the valve seat. As will be further exemplified below, this maximum distance is twice the eccentricity if the eccentric sleeve shaft is rotated by 180°. Hence, by rotating the inner eccentric sleeve shaft from a position where the eccentricity position (position of the offset center of the bore or center of the shaft placed in said bore) is in a vertically uppermost eccentricity position (shutter closed) by 180° to its lowermost position, the shutter may be entirely unclamped by a distance twice the eccentricity. Hence, by appropriately choosing the eccentricity, the shutter may be unclamped and moved far enough from the valve seat to be tilted away by the secondary tilting motion. This secondary tilting motion simply requires rotating the shaft within the eccentric bore by a sufficient angle.
It has been observed however that at least for a number of applications, wear of the valve seat and gasket is increased to an undesirable extent, if the initial unclamping of the shutter from the valve seat implies movements off-parallel to the valve seat's central axis.
Hence, in a further embodiment, the inner eccentric sleeve shaft is arranged within the outer cylindrical sleeve such that the eccentricity position is located laterally by about the eccentricity distance from the center of the outer cylindrical sleeve when the shutter is in the sealed closed position. In other words, in such an embodiment, the primary motion does not start from a vertically uppermost eccentricity position, but rather from a situation where the position of the eccentric sleeve shaft is rotated by 90° with respect to the uppermost vertical position.
Remarkably, such a configuration provides an advantageous initial component of the primary motion which is almost parallel to the axis of the valve seat, thereby allowing a comparatively gentle, wear reducing unclamping operation. In such configurations, the primary motion will imply that the inner eccentric sleeve preferably is rotated by an angle of 90°, which moves the shutter by vertical and horizontal distances equal to the eccentricity.
Hence, even the use of only one eccentric sleeve shaft for the primary motion allows for an initially almost translational unclamping. This means that at the beginning of the opening, the movement provided by the eccentric is such that the shutter is lifted from the seat with an almost straight path, essentially parallel to the axis of the valve seat.
If desired or necessary, the translational part of the primary motion may even be enhanced by a further constructionally simple variant of the sealing valve arrangement of the disclosure.
In such a further embodiment, the primary motion assembly further comprises an outer eccentric sleeve shaft (second eccentric sleeve shaft) rotationally mounted within said outer cylindrical sleeve, wherein said inner eccentric sleeve shaft (first eccentric sleeve shaft) is rotationally mounted within said outer eccentric sleeve shaft (second eccentric sleeve shaft), the primary motion being a function of the eccentricity and angular rotation of both inner and outer eccentric sleeve shafts.
By combining two nested (first and second) eccentric sleeve shafts, each one being rotationally movable, the primary motion can be adjusted again as a function of the eccentricity and angular rotation, but this time, of those of the inner and of the outer eccentric sleeve shaft. Their eccentricity and their rotation angle may be adapted independently to best fit the actual situation and the objectives set by the operator. As it will be easily understood with the examples provided below, the allowable maximum (net) distance will be twice the sum of both eccentricities if both eccentric sleeve shafts are rotated by 180°.
However, a double eccentric sleeve shaft assembly further allows a primary motion which may be particularly advantageous or desirable in certain situations. Hence, in a still further embodiment with two eccentric sleeve shafts, the inner and outer (first and second) eccentric sleeve shafts have the same eccentricity. Furthermore, an eccentric actuator is preferably configured to impart a simultaneous counter-rotating angular rotation to said inner and outer eccentric sleeve shafts. In fact, by combining the same eccentricity and simultaneous counter-rotating by the same angle of both (inner and outer) eccentric sleeve shafts, the primary motion becomes entirely translational without lateral shifting at any time during the primary motion, i.e. the path of the shutter during primary motion is entirely straight.
The primary and secondary motion may be effected by an appropriate number of separate actuators. In general, the use of one actuator per motion assembly will allow a convenient control without adding undue complexity to the sealing valve arrangement. Nevertheless, it might be desirable or necessary to further reduce the number of parts of a sealing arrangement as described herein.
Hence, in a still further embodiment, the tilting shaft actuator may be a control rod used to concomitantly rotate the tilting shaft with the rotation of the inner (or outer) eccentric. In one embodiment such a control rod is rotationally connected with one end to a stationary point and with the other to the tilting shaft or to a crank associated therewith, such that the rotating of the eccentric (primary motion) with an actuator, such as a hydraulic jack or similar, drives the rotation of the tilting shaft (secondary motion) by means of the control rod.
In the context of the disclosure, it is to be understood that a greater number of nested eccentric sleeve shafts can be used if desired or deemed useful. In general however, the complexity of the assembly and especially of the actuation mechanism rapidly increases with higher numbers of eccentric sleeves.
In a still further embodiment, the secondary motion of tilting the shutter to its parking position could be further assisted or completed by concomitantly or subsequently to the secondary tilting motion also rotating the eccentric sleeve shaft (or any or more of them if present) by a further angle. For example, by rotating the eccentricity position(s) of the eccentric sleeve shaft(s) to the side of the parking position, the shutter may be placed still further away from the center of the valve as it would by only the secondary motion.
Although above only the shutter opening operation has been described, it is clear to the skilled person that closing the shutter basically implies reverting the steps described for opening, it being understood that slightly departing from the exact reverse order may be considered if desired.
The tilting arm preferably is a cantilever arm that is supported at one end portion by said tilting shaft inside the inner eccentric sleeve shaft and at another end portion carries the shutter. The shutter may be of any appropriate type, preferably the shutter is a conical, spherical, parabolic or flap type valve shutter.
Preferably, the one or more eccentric sleeve shafts, as well as the tilting shaft within the integrated dual-motion shutter-actuating device are rotationally mounted with axially spaced bearings.
With the disclosure a number of advantages can be achieved compared to existing solutions, among which the most important benefits are:
A preferred embodiment of the disclosure will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 4A1-B2 is a series of cross sectional views of a third embodiment of a valve sealing arrangement showing the integrated dual-motion shutter-actuating device with two eccentric sleeve shafts; and
Further details and advantages of the present disclosure will be apparent from the following detailed description of several not limiting embodiments with reference to the attached drawings.
Within the offset bore of the inner eccentric sleeve shaft 20 the cylindrical shaft connected at one end to tilting arm 30 and at the other end to tilting crank 31 is mounted with means of bearings 36 to rotate about axis B when tilting crank 31 is actuated.
The eccentricity in the embodiment of
The primary motion is effected by rotating eccentric sleeve shaft 20 by moving eccentric crank 21 from the position shown in
The tilting operation (secondary motion) is effected by rotating the tilting shaft around axis B by means of an actuator (not represented) turning tilting crank 31 counterclockwise at a sufficient angle to clear the passage of the valve.
The initial almost straight vertical movement of a one eccentric dual-motion mechanism as described herein is further illustrated in
It is to be noted that if wear is not a (main) issue, the initial position of axis B in
In a non-illustrated embodiment of the sealing valve arrangement, secondary motion actuator 32 can be mounted (similarly to actuator 22) to a stationary point at one end and to tilting crank 32 at the other. It is noteworthy that maintaining the shutter arm vertical during the primary motion is not essential. Furthermore, even if desired, it can be achieved by other means such as by controlling the orientation of the tilting shaft by way of its actuator 32.
FIGS. 4A1 and B1 show a schematic cross section of a sealing valve arrangement wherein the integrated dual-motion shutter-actuating device comprises an inner 201 and an outer 202 eccentric sleeve shaft in an outer cylindrical sleeve 25. Both eccentrics have the same eccentricity. As a non-limiting example, in common sealing valve arrangements, each eccentricity will generally be chosen to be between 20 and 100 mm, preferably between 30 and 60 mm. Tilting shaft 37 connected at one end to the tilting arm 30 is rotationally held within the bore of the inner eccentric sleeve shaft 201. FIGS. 4A1 and B1 represent the position of the shutter before and after the primary motion, i.e. with the shutter in a sealed closed position in sealing contact with the valve seat (A1) and an open position unclamped from the valve seat (B1).
By rotating inner and outer eccentric sleeve shafts 201 and 202 simultaneously but in opposite directions the center of the tilting shaft is moved along a straight path by a distance equal to the sum of the eccentricities if each eccentric is rotated by 90° or even up to twice the sum of eccentricities if the angular rotation is 180° for each eccentric sleeve shaft.
| Number | Date | Country | Kind |
|---|---|---|---|
| LU 92 837 | Sep 2015 | LU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/070934 | 9/6/2016 | WO | 00 |
