INTRODUCTION AND BACKGROUND

This invention relates to metallurgical furnaces and more particularly to a binding and adjustment system for a furnace.

Metallurgical furnaces are used for the processing, in the form of smelting and/or melting, of ferrous and non-ferrous ores. These furnaces are generally circular or rectangular in shape and comprise a hearth and rising walls made of a refractory brick and a roof. In the case of a rectangular furnace, the hearth and walls are typically cladded on the outside by metal cladding. An array of spaced external frame members is used to secure and support the walls of the furnace. The frame members are interconnected and secured in position by a combination of rigid members and a flexible binding system. The binding system typically comprises a plurality of tie rod assemblies extending in a longitudinal direction below the hearth and above the roof from one end of the furnace to an opposite end of the furnace. In the transverse direction, the binding system typically comprises groups of independent binding actuators that are secured to a frame member and extends between the frame member and a furnace side wall. In use, and as a result of smelting or melting processes in the furnace, the furnace walls, the frames, the tie rod assemblies and the independent actuators are subjected to significant thermal and mechanical forces. The tie rod assemblies and the independent actuators comprise tensioning means for maintaining compressive forces on the hearth and furnace walls.

In an introductory part of US 6,814,012, it is mentioned that it is known to use compression spring sets as tensioning means. Various disadvantages of compression spring sets are listed and discussed. One such a disadvantage is that the known spring sets require manual adjustment to ensure that the compressive forces on the hearth and sidewalls remain relatively constant during use of the furnace. US 6,814,012 then teaches away from spring sets and discloses a tie rod assembly comprising a fluid-pressurized tensioning means. In the applicant’s view, fluid-pressurized tensioning means may prove unreliable in maintaining the intended forces under certain operating conditions and are, therefore, not suitable for at least some applications.

OBJECT OF THE INVENTION

Accordingly, it is an object of the present invention to provide a furnace binding and adjustment system with which the applicant believes the aforementioned disadvantages may at least be reduced or which may provide a useful alternative for the known systems. SUMMARY OF THE INVENTION

According to the invention there is provided a binding and adjustment system for a furnace comprising walls, the furnace binding and adjustment system comprising:

- a frame externally the walls, the frame comprising a plurality of frame members, at least some of the frame members being arranged in pairs across the furnace from one another;

- a plurality of adjustable spring-loaded actuators selectable from at least one of a) a first kind of adjustable spring-loaded actuator configured to exert an adjustable repelling force between the frame and a wall of the furnace and b) a second kind of adjustable spring- loaded actuator configured to exert an adjustable tension force in a tie rod assembly extending between a pair of frame members;

- a sensing device associated with a respective one of at least some of the plurality of adjustable spring-loaded actuators, the sensing device having an electronic signal output for providing at said output an output signal indicative of the force exerted by the respective adjustable spring-loaded actuator; and

- a remote computerized controller which is in signal communication with the electronic signal outputs and configured to generate, in response to the output signals, data for use in adjusting the force exerted by at least some of the plurality of adjustable spring-loaded actuators.

The adjustable spring-loaded actuators may be adjustable by an electromechanical arrangement

The remote computerized controller may comprise an output arrangement and the remote computerized controller may be configured to provide at the output arrangement control signals derived from the data, for controlling the electromechanical arrangement.

Each of the plurality of the adjustable spring-loaded actuators may comprise a compression spring.

Each of the plurality of the adjustable spring-loaded actuators may comprise a cylinder having a first end and a second end, the compression spring may comprise an elongate coil or cup or disc spring defining a bore and having a first end and a second end and the elongate compression spring may be located in the cylinder.

The first kind of adjustable spring-loaded actuator may comprise a first movable piston adjacent the first end of the compression spring and a second movable piston adjacent the second end of the compression spring, the first movable piston may extend beyond the first end of the cylinder and may terminate in an abutment formation which, in use, abuts the wall of the furnace and the second movable piston may extend beyond the second end of the cylinder and abut directly or indirectly via a first sandwich arrangement of axially movable components against a first adjustment formation on a first rod, the first sandwich arrangement may comprise a first collar formation immediately adjacent the first adjustment formation and the first adjustment formation may be adjustable on the first rod in an axial direction, to adjust compression in the compression spring.

The second adjustable spring-loaded actuator may comprise a movable piston defining a bore, the cylinder of the second adjustable spring loaded actuator may be mounted on the tie rod assembly with a rod of the assembly extending through the bore of the compression spring and the bore of the movable piston, the movable piston abutting directly or indirectly via a second sandwich arrangement of axially movable components against a second adjustment formation, the second sandwich arrangement may comprise a second collar formation immediately adjacent the second adjustment formation and the second adjustment formation may be adjustable on the tie rod in an axial direction, to adjust compression in the compression spring. At least one of the first adjustment formation and the second adjustment formation may comprise a threaded nut which locates on a threaded part of the first rod and the tie rod, respectively.

The nut may be manually manipulatable, to adjust its axial position.

The furnace binding and adjustment system may comprise a remotely controllable nut releasing device and a remotely controllable nut manipulating device which are controlled by the remote computerized controller.

The remotely controllable nut releasing device may comprise a fluid pressure operable mechanism to move the axially movable first collar formation or second collar formation axially against the bias of the compression spring away from the nut, thereby to release the nut, to be manipulated.

The remotely controllable nut manipulating device may comprise a rotatable formation defining a suitably shaped socket for accommodating at least part of the nut and means for rotatably driving the rotatable formation in a selectable one of a clockwise direction and an anti-clockwise direction.

The drive means comprises an electric motor and drive train connected between the rotatable formation and the electric motor. The remote computerized controller may be configured, in response to the output signals, to generate control signals for controlling the nut releasing devices of designated ones of the plurality of adjustable spring-loaded actuators to release nuts of these designated actuators and then to cause the nut manipulating devices of these designated actuators to manipulate said nuts.

At least one of the first sandwich arrangement and the second sandwich arrangement may comprise a first sensing device.

BRIEF DESCRIPTION OF THE ACCOMPANYING DIAGRAMS

The invention will now further be described, by way of example only, with reference to the accompanying diagrams wherein: figure 1 is a diagrammatic perspective view of a furnace system comprising a rectangular furnace and a furnace binding and adjustment system for providing structural integrity to the furnace during operation; figure 2 is a perspective view of a tie rod assembly comprising interconnected tie rod segments, an adjustable spring-loaded actuator and first and second load sensing devices; figure 3 is a diagrammatic perspective view of the second load sensing device on the tie rod; figure 4 is a block diagram of the first and second load sensing devices connected to a first local station and which first local station is connected to a remote computerized controller in a control room; figure 5 is a diagrammatic perspective view (partially broken away) of a first adjustable spring-loaded actuator for exerting an adjustable repelling force between the frame and a sidewall of the furnace; figure 6 is a sectional view of a second adjustable spring-loaded actuator for exerting an adjustable tension force in the tie rod assembly; figure 7 is a diagrammatic perspective view of a second embodiment of the second adjustable spring-loaded actuator; figure 8 is a sectional view of the actuator in figure 7, with a nut releasing mechanism in a first and normal operational configuration; figure 9 is a view similar to figure 8, but with the nut releasing mechanism in a second configuration enabling remote controlled and automatic electromechanical adjustment of the nut; figure 10 is a diagram similar to that of figure 1 , but with two-way communications between the remote computerized controller and the load sensing devices on the one hand and electromechanically adjustable spring-loaded actuators of the binding system, on the other hand; figure 11 is similar to figure 4 with more detail of the two-way communications of figure 10; figures 12(a) and 12(b) are schematic representations of a first alternative or additional load sensing mechanism; and figures 13(a) and 13(b) are schematic representations of a second alternative or additional load sensing mechanism.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

In figure 1 there is shown an example embodiment of a furnace system 10 comprising a rectangular furnace 12 and a binding and adjustment system 14 for the furnace. The furnace comprises opposed furnace end walls 16.1 and opposed furnace side walls 16.2 of a refractory material defining an internal hearth (not shown). The walls 16.1 and 16.2 are cladded with metal in known manner.

The furnace binding and adjustment system 14 comprises a frame 18 externally the walls. The frame comprises a plurality of frame members 20.1 , 20.2 to 20. n of which at least some of the frame members, such as members 20.1 and 20.2, are arranged in pairs across the furnace 12 from one another. A plurality of adjustable spring-loaded actuators 22 to 24 are provided. The actuators are selectable from a) a first kind of adjustable spring-loaded actuator 22 which is configured to exert a repelling force between the frame 18 and walls 16.1 , 16.2 of the furnace and b) a second kind of adjustable spring-loaded actuator 24 which is configured to exert an adjustable tension force in a tie rod assembly 26 extending between a pair of opposed frame members 20.1 and 20.2. A first sensing device 28 is associated with a respective one of at least some of the adjustable spring-loaded actuators 22, 24. The first sensing device 28 has an electronic signal output 30 (best shown in figures 1 , 4, 5 and 6) for providing at said output 30 an output signal indicative of the force exerted by the respective adjustable spring-loaded actuator 22, 24. A remote computerized controller 32 (shown in figure 4) is in signal communication with the electronic signal outputs 30 and is configured to generate, in response to the output signals, data for use in adjusting the force exerted by at least some of the plurality of adjustable spring-loaded actuators 22, 24, as will be described in more detail below.

In figure 2, an example embodiment of the tie rod assembly 26 is shown. The tie rod assembly 26 comprises a tie rod 34 comprising at least a first tie rod part or segment 34.1 and second tie rod part 34.2. Adjustable spring-loaded actuators 24 of the second kind are mounted on tie rod 34 and are configured to apply a tension force in the tie rod 34 extending between opposed frame members 20.1 and 20.2. The tie rod assembly 34 further comprises (as best shown in figure 3) a second sensing device 36 comprising a body 38 having a main axis 40, a first connector 42 for connecting the first tie rod part 34.1 to the body and a second connector 44 for connecting the second tie rod part 34.2 to the body. The first connector and second connector being spaced from one another along the main axis. The second sensing device 36 comprises a strain gauge 46 which is carried by the body 38 and for measuring a tension force applied to the body 38, in use. The tie rod assembly 26 still further comprises first sensing devices 28 (best shown in figures 2 and 4) configured to sense compression forces between a member, such as nut 48, on the tie rod and the actuator 24. The nut 48 is normally stationary on the tie rod, but its position is selectively adjustable in an axial direction to adjust the compression in the spring, as will be explained below.

Although only a rectangular furnace 12 is illustrated, it will be appreciated that the furnace may have any other suitable shape, such as circular, for example, and that a similar binding system could be adopted albeit suitably adapted.

Referring to figure 1 , the furnace 12 is of known configuration and comprises the furnace walls comprising opposed metal cladded vertically extending end walls 16.1 and opposed metal cladded vertically extending side walls 16.2 collectively defining the hearth towards a bottom internal region of the furnace and a roof 50. The hearth and walls are made of refractory brick. Electrodes (not shown) extend through the roof into the furnace.

The binding system 14 typically comprises the frame 18 (comprising an array of spaced frame members 20.1 to 20. n), a plurality of tie rod assemblies 26 and a plurality of the first kind of adjustable spring-loaded actuators 22. Some tie rod assemblies extend below the hearth between opposed frame members adjacent the opposed end walls 16.1 and others extend above the roof 50 between opposed frame members adjacent the opposed end walls. The first kind of adjustable spring-loaded actuators 22 are mounted between adjacent frame members, such as members 20.3 and 20.4 in figure 1 , to exert a repelling force between the frame and the walls.

First load sensing device 28 may for example be a device such as that supplied by Earth System srl under the name “Anchor load cell”. The device is ringshaped and comprises an electronic signal output 30 for a signal indicative of the pressure or compression forces sensed by the first load sensing device 28.

The second load sensing device 36, which is sensitive to strain on body 38, is fully described in the applicant’s international application PCT/IB2020057950 entitled “Load Monitoring Device”, the contents of which are incorporated herein by this reference. The strain gage 46 of the second load sensing device 36 comprises an electronic signal output 52 (shown in figure 4) for a signal indicative of the strain sensed by the second load sensing device 36.

The first kind of adjustable spring-loaded actuator 22 is best shown in figure 5. These actuators are mounted between adjacent frame members, such as frame members 20.3 and 20.4. The actuator comprises a cylinder 54 having a first end 56 and a second end 58. A compressed compression spring 60 having a first end and a second end is located in the cylinder. The first end of the compression spring abuts directly or indirectly (via optional other components) against a first movable piston 62 which extends beyond the first end of the cylinder, to abut against the furnace sidewall 16.2. The second end of the compression spring 60 abuts directly or indirectly (via optional other components) against a second movable piston 64. The second movable piston extends beyond the second end of the cylinder and abuts directly or indirectly via a first sandwich arrangement 66 of axially movable components against a first adjustment formation 68 (in this example embodiment in the form of an internally treaded nut) on an externally threaded portion of a first rod 70, which rod is mounted fast with the frame 20. The first sandwich arrangement 66 comprises a first collar formation 72 immediately adjacent the nut 68. The nut 68 is adjustable on the first rod in an axial direction, to adjust compression in the compression spring 60. The first sandwich arrangement 66 also comprises first load sensing device 28 having output 30.

The second kind of adjustable spring-loaded actuator 24 is best shown in figure 6. The actuator 24 comprises a compression spring 80 (in this embodiment in the form of an elongate compression spring) located in a cylinder 82 having a first end 84 and a second end 86. The actuator further comprises a movable piston 88 defining a bore 90. The tie rod 34 extends through the cylinder and the bore 90. The cylinder, at the one end 84 thereof, is mountable against stationary frame member 20.1. The compression spring 80 abuts directly or indirectly against movable piston 88. Movable piston 88 extends beyond the second end 86 of the cylinder and abuts directly or indirectly via a second sandwich arrangement 92 of axially movable components against a second adjustment formation 94, in this embodiment in the form of an internally threaded nut, on an externally threaded end portion 98 of tie rod 34. The second sandwich arrangement 92 comprises a second collar formation 96 immediately adjacent nut 94. The nut 94 is adjustable on the tie rod 34 in an axial direction, to adjust compression in the compression spring. The second sandwich arrangement 92 also comprises a first sensing device 28 having an output 30. The nut 94, when manipulated, cooperates with the threaded portion of the tie rod and is used to adjust the compression in the spring and thereby a tension force exerted on the tie rod 34, in use.

As best shown in figures 1 and 4, the electronic signal outputs 30 and 52 are connected by electrical wires 100 and 102 respectively to a first local station 104 in suitable proximity to the furnace 12. The first station 104 may be in the form of a junction panel. As best shown in figure 4, the first station 104 is in signal or data communication with a second station, which may be in a control room 106. In this example embodiment the control room 106 houses the remote computerized controller 32. The controller may comprise a computer system or server 108, a database 110 connected to the server and monitors 112 for use by a human operator 114.

Output signals or data from the first and second sensing devices 28 and 36 on the plurality of tie rod assemblies 16 and actuators 22 are processed under control of a computer program running on the computerized controller 32 and resulting data is displayed on the monitors. The data enables the operator 114 to instruct a second human operator (not shown) to attend the furnace and manually, by means of suitable tools (also not shown), to manipulate the nuts 68, 48 of designated actuators 22, 24, thereby to adjust the compression in the relevant compression springs and the forces exerted by the actuators 22, 24.

A second embodiment of the second kind of actuator 24 is shown in figures 7 to 9 and is generally designated 120. The second embodiment 120 of the second actuator comprises the actuator 24 (as described above with reference to figure 6) as well as a remotely controllable hydraulically operable device 122 (best shown in figures 8 and 9) to release the nut 94 from collar formation 96 and a remotely controllable nut manipulating device 124. It will be appreciated that a second embodiment 121 (shown in figure 11 ) of the first kind of actuator 22 may comprise a similar remotely controllable nut releasing device and a similar remotely controllable nut manipulating device which operate in a manner similar to that described below in respect of the second embodiment 120 of the second kind of actuator.

Referring to figures 8 and 9, the nut releasing device 122 comprises a cylinder and piston assembly 126 comprising a hydraulic cylinder 128 which is threaded onto the threaded end portion 98 of the tie rod 34. A cooperating cylindrical piston part 130 has an end 132 defining an opening 134 which is large enough for the nut 94 to pass through. The piston part 130 is mounted coaxially on the tie rod with the end 132 abutting against collar formation 96. The assembly 126 defines an annular chamber 136 for a pressurizing fluid, preferably hydraulic fluid. A remotely controllable pump (not shown) controls the admission into and withdrawal from chamber 136 of the hydraulic fluid via conduit 138.

In a first or normal operating configuration of the tie rod assembly (shown in figure 8) the nut 94 abuts against the collar formation 96 as described above. The nut is releasable from the collar formation 96 by admitting the hydraulic fluid into chamber 136. This causes of the chamber 136 to expand and cylindrical piston 130, its end 132, collar formation 96 and the above second sandwich arrangement (including first sensing device 28) between end 132 and the movable piston 88 to move in a direction A away from the nut 94, thereby to release the nut from the collar formation 96 and so that the nut 94 becomes manipulatable. The nut manipulating device 124 comprises a rotatable member 140 defining a suitably shaped socket for accommodating the nut 94. The member 140 is rotatable selectively in a clockwise or anti-clockwise direction by an electric motor 142 via a shaft 144 and gear train 146 which is housed in a gearbox 148.

As best illustrated in figures 10 and 11 , the pump and electric motor for the nut releasing device 122 and nut manipulating device 124 respectively of the second embodiment 120 of the second kind of actuator and the pump and electric motor for the nut releasing device and nut manipulating device respectively of the second embodiment 121 of the first kind of actuator are controllable by the control signals 150 from the remote computerized controller 32 in the control room 106.

Hence, in use, should the computerized controller 32 determine from signals 152 received from the sensing devices 28, 36 that adjustment of the compression spring 60, 80 of any one of the plurality of actuators 120, 121 is required, the necessary control signals 152 are generated, first to drive with control signal 154 the pump to release the relevant nut 48, 68 (as explained above) and then with control signal 156 the electric motor to manipulate the released nut in the required direction. It will be appreciated that with the second embodiment 120 of the first kind of actuator and the second embodiment 121 of the second kind of actuator and the two-way signal communications 152, 150, 154, 156 shown in figure 11 , the second human operator is not required to manually manipulate the relevant and designated nuts 48,68.

A first alternative and/or additional load sensing mechanism 200 is shown in figures 12(a) and 12(b) and second alternative or additional load sensing mechanism 300 is shown in figures 13(a) and 13(b).

With reference to the second kind of actuator 24, the first mechanism 200 comprises means for measuring change in a distance di between a point 202 on cylinder 82, which abuts against frame member 20.1 , and a stationary point 204 on the tie rod 34. The change in distance is proportional to the length of the compression spring and therefore compression of the compression spring. By using the well-known formula F = Kdi, a change in the force exerted by the spring 80 is calculated.

Referring to figure 13(a) and (b), the change in distance may be measured by means of spaced proximity switches 302, 304 and 306 on the tie rod 34.