Abstract:
The invention concerns a device for dispensing bulk materials through a rotary chute with variable angle of inclination comprising an underslung rotor mounted in a supporting frame so as to rotate about a substantially vertical axis of rotation. The chute is suspended from the rotor so as to pivot about a substantially horizontal axis of suspension. A mechanism for pivoting the chute comprises a hydraulic motor mounted on the underslung rotor. A hydraulic connecting device comprises a sleeve fixed in rotation and a rotary sleeve driven in rotation by the rotor. The sleeves co-operate to connect the hydraulic motor to a control hydraulic circuit fixed in rotation. A duct feeding the chute passes through the two sleeves. The device can advantageously equip a shaft furnace.

Description:
The present invention relates to a device for distributing materials in bulk with a rotary chute having a variable angle of inclination. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     Such devices are used, for example, in devices for charging shaft furnaces, particularly blast furnaces, in which the rotary chute with a variable angle of inclination provides for the distribution of the charge inside the shaft furnace. More particularly, they comprise a supporting structure in which a suspension rotor is mounted in such a way that it can be driven in rotation about a substantially vertical rotation axis. The chute is suspended from this rotor so that it can be pivoted by a pivoting mechanism about its suspension axis. This pivoting mechanism makes it possible to change the inclination of the chute during its rotation. The rotor is traversed axially by a feed channel so that the materials in bulk, which flow from a batch hopper in the charging device, are poured into the rotary chute, which distributes them inside the shaft furnace. 
     Such devices for distributing materials in bulk are, for example, described in the documents WO 95/21272, U.S. Pat. Nos. 5,022,806, 4,941,792, 4,368,813, 3,814,403 and 3,766,868. In these devices, the pivoting mechanism comprises a second rotor, which has a rotation axis substantially coaxial with the first rotor, from which the chute is suspended. While the first rotor mainly gives the chute a rotation about a vertical axis, the second rotor interacts with the chute so as to determine its angle of inclination. For this purpose, the second rotor is connected to the chute by a mechanism converting a variation in angular displacement between the two rotors into a variation in the angle of inclination of the chute in its vertical pivoting plane. These devices were designed for large diameter blast furnaces. Their pivoting mechanism is too complicated and too expensive to equip small or medium-sized shaft furnaces. 
     An improved device for distribution material in bulk with a rotary chute having a variable angle of inclination, in which simpler means are used to change the inclination of the rotary chute and which ensure reliable operation, is needed. 
     SUMMARY OF THE INVENTION 
     A device of the present invention provides a suspension rotor mounted in a supporting structure so that it can rotate about a substantially vertical rotation axis. The chute is suspended from this suspension rotor so that it can pivot about a substantially horizontal suspension axis. The suspension rotor is traversed axially by a feed channel for the chute. It should be appreciated that the present invention proposes a very simple and very compact pivoting mechanism for changing the inclination of the chute in this way. This pivoting mechanism comprises a hydraulic motor, for example a hydraulic cylinder, which is mounted on the suspension rotor and connected to the chute so as to make it pivot about its suspension axis. An annular hydraulic connecting device is used to connect this hydraulic motor to a hydraulic control circuit. This hydraulic connecting device comprises more particularly a non-rotatable sleeve and a rotary sleeve driven in rotation by the rotor. The feed channel for the chute passes axially through these two sleeves, which cooperate in order to connect the hydraulic motor driven in rotation by the rotor to a non-rotatable hydraulic control circuit. 
     The annular hydraulic connecting device is preferably positioned above the supporting structure, which is designed as a leak-proof housing traversed in a gastight manner or almost in a gastight manner by the upper end of the rotor. This arrangement makes for easier maintenance and shields the connecting device from unfavourable environments (heat, corrosive smoke, vapours, dust) which may prevail inside the supporting structure. 
     In a first embodiment of the annular hydraulic connecting device, the rotary sleeve is supported by the rotor, and the non-rotatable sleeve is supported by the rotary sleeve. Bearings, comprising for example two bearing rings, may in this case support the non-rotatable sleeve on the rotary sleeve. A flexible annular expansion joint enables the non-rotatable sleeve to be connected in a gastight manner to the supporting structure, while allowing the non-rotatable sleeve small movements with respect to the supporting structure. It should be particularly appreciated that such an annular hydraulic connecting device is relatively insensitive to impacts experienced by the rotor. 
     In a second embodiment of the hydraulic connecting device, the non-rotatable sleeve is supported flexibly by said supporting structure and the rotary sleeve is supported by the nony, rotatable sleeve. In this embodiment, the non-rotatable sleeve and the rotary sleeve preferably have a fit designed in such a way that a pressurized hydraulic fluid injected between the two warrants a self-centering of the rotary sleeve in the non-rotatable sleeve. It should be appreciated that such a hydraulic connecting device requires fewer sealing joints between the two sleeves, which reduces the cost of the device and the maintenance expenses (fewer sealing joints to be replaced). The elimination of sealing joints between the two sleeves further means a considerable reduction in losses due to friction in the device, given that the power absorbed in a sealing joint may be as much as several kW. 
     For the transfer of the hydraulic liquid between the non-rotatable sleeve and the rotary sleeve, the hydraulic connecting device incorporates, for example, superposed supply channels. In a preferred embodiment, the drainage means are placed above and below these supply channels so as to collect the leakage flow from the adjacent supply channel. This leakage flow can then be used to supply at least one cooling circuit which is locked to the suspension rotor and rotates with it. In this case, the rotary sleeve advantageously includes a hydraulic circuit communicating with the drainage means and supplying at least one cooling circuit. 
     A tubular screen, non-rotatable and provided with a cooling circuit, is advantageously inserted between the feed channel and the rotary annular connecting device. This tubular screen is preferably supported by an outer wall of the supporting structure, so as to form with this outer wall an annular chamber in which the annular connection is housed. 
     In a preferred embodiment, the supporting structure is provided at its lower end with a fixed annular screen fitted with a cooling circuit and defining a circular central opening. The suspension rotor is then provided with a flange at its lower end. Said flange is fitted with clearance in the central opening of the fixed annular screen and has cavities opening into its lateral edge. A gas injection pipe is positioned along the free edge of the fixed annular screen so that a coolant gas can be injected into the cavities of the flange of the suspension rotor. It should be appreciated that such a system of fixed and mobile screens may be advantageously used in any device for distributing materials in bulk with a rotary chute having a variable angle of inclination in order to provide effective separation between the inside of the supporting structure and an unfavourable environment (for example: heat, corrosive smoke, vapours, dust) which may prevail under the supporting structure. 
     It should further be appreciated that the invention further provides a device for indicating the inclination of the chute. This device may be advantageously used in any device for distributing materials in bulk with a rotary chute having a variable angle of inclination. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other characteristics of the invention will emerge from the detailed description of a number of advantageous embodiments given below, as illustrative examples, making reference to the appended drawings. These drawings show: 
     FIG.  1 : a vertical cross-section through an installation for charging a shaft furnace provided with a device for distributing materials in bulk with a rotary chute having a variable angle of inclination according to the invention; 
     FIG.  2 : a simplified three-dimensional view of a device for distributing materials in bulk according to the invention, drawn partly in the form of a cross-section; 
     FIG.  3 : a diagrammatic cross-section through a first embodiment of an annular connecting device provided in a device for distributing materials in bulk according to the invention; 
     FIG.  4 : a diagrammatic cross-section through a device for distributing materials in bulk with a rotary chute having a variable angle of inclination provided with a device for indicating the angle of inclination of the chute; 
     FIG.  5 : a cross-section along the cutting line A—A in FIG. 4; 
     FIG.  6 : a diagrammatic cross-section through a second embodiment of an annular connecting device provided in a device for distributing materials in bulk according to the invention; 
     FIG.  7 : a cross-section showing an enlarged detail from FIG. 6; 
     FIG.  8 : a view of a detail from FIG.  6 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the figures, the same reference numbers indicate identical or similar elements. 
     FIG. 1 shows a diagrammatic representation of an installation for charging a shaft furnace  10 . This installation is provided with a device for distributing materials in bulk  12  with a rotary chute  14  having a variable angle of inclination. Above the distributing device  12  is positioned a batch hopper  16 , which is supported by means of a supporting structure  18  on the shaft furnace  10 . The hopper  16  opens into a feed channel  20 . The reference number  21  indicates the central axis of the feed channel  20  which will normally be coaxial with the central axis of the shaft furnace  10 . 
     In FIG. 1, the chute  14  is shown in two positions. The full lines show it in an almost vertical position, in which it is not operational. The material in bulk is in fact poured through the feed channel  20  into the central region of the shaft furnace  10 . The broken lines show the chute  14  in an oblique position. In this position, the feed channel  20  pours the material in bulk into the rotary chute  14 , which ensures that it is distributed inside the shaft furnace  10  as a function of its inclination. 
     The device for distributing materials in bulk  12  will now be studied in more detail by referring simultaneously to FIGS. 1 and 2. The chute  14  is provided at its upper end with two lateral suspension arms  19 ,  19 ′ (in FIG. 1, the arm  19 ′ is hidden by the arm  19 ). A suspension rotor  22  supports two suspension bearings  24 ,  26 . In each of these two suspension bearings  24 ,  26  is mounted a suspension arm  19 ,  19 ′ for the chute  14  so as to define for the chute  14  a substantially horizontal pivoting axis. In FIG. 2, it is possible to see a suspension journal  28  fixing a suspension arm of the chute  14  in the bearing  26 . The other suspension arm is obviously fixed in the same way in the bearing  24 . 
     The rotor  22 , which carries at its lower end the bearings  24 ,  26 , may be likened to a tube surrounding the feed channel  20 . A large diameter bearing  32 , which is mounted on a supporting flange  30  of the rotor  22 , suspends the rotor  22  in a supporting structure  34  in such a way that the rotor  22  can rotate freely about the axis  21 . An electric or hydraulic motor  36 , preferably a motor with a variable speed of rotation, is used to drive in rotation the rotor  22 , and hence also the chute  14 , about the axis  21 . For this purpose, a pinion  38  on the driving motor  36  meshes with an annular gear  40  carried by the supporting flange  30 . 
     The structure  34 , which is designed as a leak-proof housing, is itself supported on the head of the shaft furnace  10  and has at its upper end a plate  42  provided with an opening  44  for the passage of the upper end of the rotor  22 . It should be noted that the supporting flange  30  and the bearing ring  32  seal off, towards the inside of the supporting structure  34 , an annular space  45  bounded by the tubular wall of the rotor  22  in the opening  44  of the plate  42  in a leakproof or almost leak-proof way. 
     At its lower end the structure  34  is provided with an annular screen  46 . Said screen is fitted with a cooling circuit  48  on its upper surface and with insulation  50  on its lower surface. The annular screen  46  defines a central opening  52  in which a screen flange  54  is set equipping the lower end of the suspension rotor  22 . The screen flange  54  of the rotor  22  comprises an upper plate  56 , which is protected at the bottom with insulation  58 . Between the upper plate  56  and the insulation  58  there remains an empty space  60  accessible from the lateral edge of the screen flange  54 . A pipe  62  is positioned along the free edge of the annular screen  46 . This pipe  62  is connected to a source of coolant gas and it is provided along its entire length with outlets oriented so as to be able to inject this coolant gas through into the empty space  60  in the screen flange  54 . 
     It can be seen in FIG. 2 that the chute  14  has at its upper end a pivoting arm  63 . A hydraulic cylinder  64  is articulated between the pivoting arm  63  and a fixed arm  66  forming part of the bearing  26 . By actuating this cylinder  64 , the chute  14  is made to pivot in its bearings  24 ,  26 . The hydraulic cylinder  64  is supplied with a pressurised hydraulic fluid using a rotary annular connecting device surrounding the feed channel  20  of the chute  14 . 
     A first embodiment of such a rotary annular connection will be described using FIG.  3 . This rotary connection  68  comprises a non-rotatable sleeve  70  and a rotary sleeve  72  driven in rotation by the rotor  22 . In the embodiment shown, the rotary sleeve  72  is formed by an extension of the tube forming the rotor  22  above the plate  42 . The non-rotatable sleeve  70  is supported by the rotary sleeve  72  using two roller bearings  74  and  76 . A flexible annular expansion joint  78  connects the sleeve  70  to the plate  42  of the supporting structure  34 . This expansion joint  78  prevents the sleeve  70  from rotating and contributes to the leak-proof sealing-off of the annular space  45  while allowing slight movements of the sleeve with respect to the supporting structure  34 . It remains to point out that the injection of a pressurised gas into the annular space  45  makes it possible to prevent smoke entering through the bearing  32  into the annular space  45 . The rotary connecting device  68  is thus protected from the unfavourable environment (heat, corrosive smoke and vapours, dust) which may still prevail inside the supporting structure  34 , despite the screens  46  and  54  provided at the lower end of the supporting structure  34 . 
     Flexible pipes, represented diagrammatically by lines  80 ′,  82 ′ along their axes, connect the non-rotatable sleeve  70  by means of these connections  80 ,  82  to a non-rotatable hydraulic control circuit, represented diagrammatically by the block  79 . This circuit  79  may be a hydraulic circuit used conventionally for controlling a double-acting piston. The arrows pointing in opposite directions and the letters P and T indicate that the hydraulic circuit  79  may connect the connections  80  and  82  alternately to a source of pressure P or to a reservoir T. 
     The connection  80  opens into a supply channel  84  and the connection  82  into a supply channel  86 , which are both machined in a radial direction in the inner cylindrical surface of the sleeve  70 . (They could, however, further be machined in the outer cylindrical surface of the sleeve  72 .) The reference number  88  refers to a first channel for the supply of hydraulic fluid in the rotor  22 . This channel  88  has an outlet  90  in the outer cylindrical surface of the sleeve  72  at the level of the supply channel  84 . Similarly, a second channel  92  has an outlet  94  at the level of the supply channel  86 . It follows from this that each of the channels  88 ,  92  in the rotary sleeve  72  is permanently in hydraulic communication with the corresponding supply channel  84 ,  86  in the nonrotatable sleeve  70 . In other words, through the connections  80 ,  82 , the supply channels  84 ,  86 , the outlets  90 ,  94  and the channels  88 ,  92 , it is possible to supply, in a closed circuit, hydraulic equipment on the rotor  22  with a pressurised hydraulic fluid. FIG. 1 shows a diagrammatic representation of the flexible pipes  96 ,  98  which connect the channels  88 ,  92  to the hydraulic cylinder  64 . 
     In the embodiment of FIG. 3, each of the supply channels  84 ,  86  has sealing rings  100  running alongside them. However, said sealing rings cannot guarantee that the sealing between the non-rotatable sleeve  70  and the rotary sleeve  72  is perfect, so that an axial leakage flow is set up between the two sleeves  70  and  72 . It should be appreciated that this axial leakage flow is advantageously used to lubricate the roller bearings  74  and  76 . For this purpose, a third supply channel  102  is provided between the two supply channels  84 ,  86 . This supply channel  102  is used to collect the leakage flow between the two supply channels  84 ,  86  in order to discharge it through a channel  104  into a lubrication chamber  106  for the roller bearing  76 . This chamber  106  further receives the leakage flow passing through the sealing ring  100  located below the supply channel  84 . After having lubricated the roller bearing  76 , the axial leakage flow collected in the chamber  106  passes through a channel  108  into a lubrication chamber  110  for the roller bearing  74 . This chamber  110  further receives the leakage flow passing through the sealing ring  100  located above the supply channel  86 . After having lubricated the roller bearing  74 , the leakage flow is finally discharged through a channel  112  outside the rotary connection  68 . A sealing collar  114 ,  116  fixed to the non-rotatable sleeve  70  provides for some sealing between the non-rotatable sleeve  70  and the rotary sleeve  72 , respectively, above the upper roller bearing  74  (as regards the sealing collar  114 ) and below the lower roller bearing  76  (as with regards to the sealing collar  116 ). 
     The reference number  120  refers generally to a non-rotatable screen equipped with a closed cooling circuit  122 . This cooling screen  120  is mounted in an annular space remaining between the rotary sleeve  72  of the rotary connection  68  and a fixed wearing tube  123  forming the feed channel  20 . It mainly serves to cool the inner surface of the rotor  22 . The arrows  124  stand for a cooling liquid passing through the closed cooling circuit  122 . The cooling sleeve  120  and the wearing tube  123  are both supported by the non-rotatable sleeve  70 . An expansion joint  126 , which can be seen more clearly in FIGS. 1 and 2, connects the feed channel  20  in a gastight manner to the batch hopper  16 . 
     A second embodiment of an annular rotary connection will be described with the help of FIGS. 6 to  8 . This rotary connection  268  comprises a non-rotatable sleeve  270  and a rotary sleeve  272  driven in rotation by a suspension rotor  222 , which is equivalent to the suspension rotor  22 . The upper end of the rotor  222  protrudes only slightly with respect to the upper plate  42  of the structure  34 . The rotary sleeve  272  is located above this upper end of the rotor  222  and is coupled to it by dowels  273  (see FIG.  7 ). These dowels  273  enable the rotor  222  to drive in rotation the rotary sleeve  272 , while allowing some freedom as regards small relative movements between the rotor  222  and the sleeve  272 . It should further be appreciated that this arrangement enables the rotary connection  268  to be exchanged en bloc without having to remove the rotor  222 . 
     The non-rotatable sleeve  270  is supported flexibly on the plate  42  by means of elastic supports  278 . The rotary sleeve  272  is supported in the non-rotatable sleeve  270  by means of thrust bearings  274 ,  276  which cooperate, for example, with a flange  277  on the rotary sleeve  272 . 
     The reference number  279  refers to at least two connections making it possible to connect the rotary connection  268  to a hydraulic circuit (not shown). This connection  279  passes in a gastight manner through a fixed wall  281  which surrounds the rotary connection  268 . It can be seen that the connection  279  is designed so as not to impede small movements of the sleeve  270  on its elastic supports  278 . A connecting channel  280  connects the first connection  279  to a supply channel  284 . A connecting channel  282 , located outside the cross-sectional plane of FIG. 6, connects the second connection (not shown) to a supply channel  286 . The supply channels  284  and  286  are both machined in a radial direction in the inner cylindrical surface of the sleeve  270 . (Further, the supply channels  284 ,  286  could be machined in the outer cylindrical surface of the sleeve  272 .) The reference number  288  refers to a feed channel for hydraulic fluid in the rotor  222 . This channel  288  has an outlet  290  in the outer cylindrical surface of the sleeve  272  at the level of the supply channel  284 . A second channel  292  (located outside the cross-sectional plane) similarly has an outlet  294  at the level of the supply channel  286 . It follows from this that each of the channels  288 ,  292  is permanently in hydraulic communication with the corresponding supply channel  284 ,  286  in the non-rotatable sleeve  270 . 
     At the lower end of the rotary sleeve  272 , each of the channels  288 ,  292  is connected through a flexible pipe to a distribution channel  288 ′,  292 ′ made in the rotor  222 . FIG. 8 shows such a flexible pipe  293 . It should be noted that it lies along the joint between the rotary sleeve  272  and the rotor  222  over a certain distance in order to have a greater deformable length, and thus a better flexibility, in order to compensate for relative movements between the rotary sleeve  272  and the rotor  222 . In conclusion, through the connecting channels  280 ,  282 , the supply channels  284 ,  286 , the outlets  290 ,  294 , the channels  288 ,  292 , the flexible pipes  293  and the distribution channels  288 ′,  292 ′, it is possible to supply hydraulic equipment, which is locked in rotation to the rotor  222 , with a pressurized hydraulic fluid. 
     It should be pointed out that a fairly large leakage flow escapes laterally from whichever of the two supply channels  284  or  286  is supplied with the pressurized hydraulic fluid. This pressurized leakage flow penetrates wedge-shaped annular slits made between the two sleeves  270 ,  272  on both sides of the supply channels  284 ,  286  and causes a hydrostatic self-centring of the rotary sleeve  272  in the non-rotatable sleeve  270 . At the same time, it provides an optimum cooling of the two sleeves  270  and  272 . 
     It is further possible to use the aforesaid leakage flow as a liquid for supplying the closed cooling circuits which are locked in rotation to the rotor  222 . For this purpose, the rotary sleeve  272  incorporates, for example, drainage means  295 ,  297 , which are located respectively above and below the two supply channels  284 ,  286  so as to collect the leakage flow from the adjacent supply channel  284 ,  286 . These drainage means  295 ,  297  open into a supply channel  299  made in the rotary sleeve  272 . At the lower end of the rotary sleeve  272 , the supply channel  299  is connected through a flexible pipe (see, for example, FIG. 8) to a distribution channel  299 ′ made in the rotor  222 . This distribution channel  299 ′ makes it possible to supply a cooling circuit locked in rotation with the rotor  222  with the hydraulic leakage flow as cooling fluid. The reference number  301  refers to a return channel for this cooling fluid in the rotary sleeve  272 , which is connected in the way described above to a return channel of the cooling circuit locked in rotation with the rotor  222 . The return channel has an outlet  303  at the level of a supply channel  305  machined in a radial direction in the inner cylindrical surface of the sleeve  270 . This supply channel  305  has a sealing ring  307  running alongside it and it opens into a channel  306  for discharging the leakage flow into a reservoir (not shown). It remains to point out that a part of the leakage flow is advantageously used to lubricate the thrust bearing  274 , while the thrust bearing  276  has a separate lubricating system. 
     The reference number  320  refers generally to a non-rotatable screen equipped with a cooling circuit  322 . This non-rotatable screen  320  is equivalent to the non-rotatable screen  120  of FIG.  3 . It is supported, together with a wearing tube  323  defining the feed channel  20 , by the fixed wall  281  and forms with said wall an annular chamber  325  in which the rotary connection  268  is housed. This arrangement has the particular advantage that the vibrations absorbed by the wearing tube  323  during the passage of the charging material in the channel  20  are not transmitted to the rotary connection  268 . 
     FIGS. 4 and 5 serve to illustrate a device for indicating the inclination of the chute, which can be advantageously used in a device for distributing material in bulk with a rotary chute having a variable angle of inclination. The reference number  350  refers to a roughly horizontal ring mounted on the suspension rotor  22  so that it can slide vertically along said rotor. For this purpose, the ring  350  is, for example, provided with guide rods  352 ,  354  which are received in slides  356 ,  358  carried by the rotor  22 . A connection mechanism connects this ring  350  to the chute  14  so that a pivoting of the chute  14  causes a vertical displacement of the ring  350 . It follows from this that the vertical position of the ring  350  is a function of the inclination of the chute  14 . The reference number  360  refers generally to a position detector  360 , which is mounted on the upper plate  42  of the supporting structure  34  to detect the vertical position of the ring  350 . This detector  360  is, for example, provided with a detecting rod  362  which penetrates the structure  34  so that it can bear with its front end against the ring  350  rotating with the rotor  22 . A spring  364  ensures a permanent contact between the front end of the rod  362  and the rotating ring  350 . It follows from this that the length of the rear end  366  of the rod  362  which emerges from the supporting structure  34  is a faithful image of the vertical position of the ring  350  and hence of the inclination of the chute  14 . In a preferred embodiment, the connection mechanism which connects the ring  350  to the chute  14  consists, on each suspension arm  19 ,  19 ′ of the chute  14 , of a pair of toothed segments  372 ,  374  which mesh together. The toothed segment  372  is fixed to the chute so that its axis is coincident with the pivoting axis of said chute. The toothed segment  374  is mounted on the rotor  22  so that it can rotate freely about an axis parallel to the pivoting axis of the chute  14 . Each toothed segment  372 ,  374  is connected by an articulated linking rod  376 ,  378  to the ring  350 . It should be appreciated that this mechanism ensures a parallel displacement of the ring  350  when the chute  14  pivots about its pivoting axis.