Furnace with level detection system

Abstract

To provide an electric arc furnace with a feed material level detection system.SOLUTION: A furnace comprises a vessel having a centre axis extending between a roof and a base. The vessel holds a material having an upper surface having an upper level Iu. The furnace comprises at least one non-contact sensor for sensing a distance 32 between a reference point and a position on the upper surface. The non-contact sensor comprises: an electromagnetic signal transmitter-receiver; an antenna for reflecting a signal toward the upper surface and receiving the reflection of the signal; and a signal guide extending between the transmitter-receiver and the antenna. The transmitter-receiver is located a) at a height lower than the upper level Iu or b) beyond a first line which is spaced a distance d0>0 from a layer on a line perpendicular to the centre axis in a level higher than the upper level Iu.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to furnaces, and more particularly to electric arc furnaces with feed material level detection systems. [Background technology]

[0002] EP2564141B1 discloses a furnace having a bottom, at least one sidewall, and a roof, which collectively form a furnace vessel for containing material being processed therein. The furnace includes at least one non-contact sensor, which is used to measure the position, or level, of the material within the furnace relative to the sensor. Based on the level of material within the furnace, one or more operating parameters of the furnace, such as the rate at which additional material is introduced into the vessel or the rate at which material is withdrawn from the vessel, can be modified. As shown in Figure 1 (also Figure 1 of EP2564141B1), a sensor 110 is positioned directly above a feed material layer 120. The sensor typically includes at least one transmitter in a fixed position directly above the feed material layer and at least one receiver directly above the feed material layer. The sensor 110 may be located within, below, or above the roof 106, but in any case, it is located directly above the feed material layer 120. In these situations, a special housing or shield 134 is provided at least partially around each non-contact sensor 110 to electromagnetically shield the non-contact sensor 110 from electromagnetic interference (“EMI”) that exists between the non-contact sensor 110 and the feed material layer 120. In at least some embodiments, the EMI shield 134 comprises, at its lower end facing the layer, a thermal radiation shield 136 in the form of a replaceable cassette containing a fire-resistant fabric.

[0003] The above configurations and arrangements of the at least one non-contact sensor are not suitable for at least some applications in the sense that they may be too complicated to commission and / or maintain and service, may be too exposed to the harsh furnace environment, may be too large, or may be too expensive. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] EP2564141B1 Summary of the Invention [Problem to be solved by the invention]

[0005] It is therefore an object of the present invention to provide an electric furnace which the applicant believes may at least alleviate the above-mentioned drawbacks or may be a useful alternative to known furnaces. [Means for solving the problem]

[0006] According to the present invention, at least one electrode; A vessel having a base, at least one sidewall, and a roof area including a roof, for holding material to be processed, the vessel having a central axis extending between the roof and the base, the material being at an upper level (l u ) and the lower level (l l a container including at least one layer having a top surface having a roof and a base, the at least one electrode extending through the roof and into the container; At least one non-contact sensor for detecting a distance between a reference point and a position on the upper surface, the non-contact sensor comprising: an electromagnetic signal transmitter; an electromagnetic signal receiver; a emitter for emitting an electromagnetic signal toward the upper surface, the emitter being located in the roof area at a distance above the upper surface; a collector for reflecting the emitted signal from the upper surface; and a signal guide at least one of a) between the transmitter and the emitter and b) between the receiver and the collector, wherein at least one of the transmitter and the receiver is located outside the container at a) an upper level (l) of the upper surface. u ) or b) located at a height lower than the upper level (l ua non-contact sensor located at a height greater than d0, spaced a distance d0>0 from the layer along a second line perpendicular to the central axis and located outside a first line extending parallel to the central axis.

[0007] The roof area includes the roof itself and the areas immediately adjacent to the roof above and below the roof.

[0008] The furnace may be an electric arc furnace.

[0009] The furnace may be a metallurgical furnace.

[0010] The layer may be the top layer of the feedstock.

[0011] The at least one non-contact sensor may be connected to a controller for generating data relating to the sensed distance.

[0012] In some embodiments, the furnace may include a plurality of non-contact sensors connected to the controller, each of the non-contact sensors for detecting a respective distance between a respective reference point and a respective one of a plurality of distributed locations on the top surface, and the controller may be operative to generate profile data relating to the top surface from the respective detected distances.

[0013] In some embodiments, the transmitter and receiver may be located at a height below the upper level of the top surface.

[0014] The transmitter and receiver may be located at a height between an upper level and a lower level of the top surface.

[0015] The transmitter and receiver may be located adjacent an exterior surface of the at least one sidewall of the container.

[0016] Alternatively, the transmitter and receiver may be located remotely from the container.

[0017] In other embodiments, the transmitter and receiver may be located at a height higher than the upper level of the top surface.

[0018] The at least one non-contact sensor may comprise any suitable type of sensor including, for example, a laser sensor, an automated sounding sensor, an acoustic sensor, an optical sensor (including digital imaging or light sensing), a muon particle sensor, a pulsed or frequency modulated electromagnetic sensor, an ultrasonic sensor, a yo-yo sensor, but is preferably a radar sensor.

[0019] The radar sensor may comprise a microwave radar transmitter and receiver.

[0020] The emitter and collector may be combined into any suitable antenna, such as a horn antenna.

[0021] A waveguide may connect the transceiver to the antenna.

[0022] The furnace may include a material feed arrangement at a feed port formed in the roof, the material feed arrangement comprising a box having an inlet for the feed material defined in a top wall and an outlet for the feed material defined in a bottom wall, the inlet being linearly offset from the outlet, the emitter and collector being aligned with the outlet to provide a direct line of sight through the outlet.

[0023] The furnace may have any suitable shape, such as rectangular, square, and circular, to name a few.

[0024] According to another aspect of the present invention, at least one electrode; a vessel having a base, at least one sidewall, and a roof region including a roof, the vessel holding a material to be treated and having a central axis extending between the roof and the base, the material including at least one layer having a top surface, the at least one electrode extending through the roof and into the vessel; and at least one non-contact sensor for detecting a distance between a reference point and a location on the top surface, the non-contact sensor comprising: an electromagnetic signal transmitting / receiving device; an antenna located in the roof area spaced above the top surface; and a signal guide extending between the electromagnetic signal transmitting / receiving device and the antenna, the transmitting / receiving device being located outside the vessel at a predetermined location where at least one of the vessel and the distance attenuates electromagnetic interference (EMI) within the vessel to an extent that no EMI shielding for the transmitting / receiving device other than an original manufacturer housing for the transmitting / receiving device is required.

[0025] According to yet another aspect of the present invention, there is provided a method of operating an electric furnace comprising: a vessel for holding material to be treated, the vessel having a base, at least one sidewall, and a roof area including a roof, the vessel including at least one layer having a top surface; at least one electrode extending through the roof into the vessel; and at least one non-contact sensor for detecting a distance between a reference point and a position on the top surface, the non-contact sensor comprising an electromagnetic signal transmitting / receiving device, an antenna located in the roof area spaced above the top surface, and a signal guide extending between the electromagnetic signal transmitting / receiving device and the antenna, the method comprising: disposing the transmitting and receiving device outside the container; utilizing the signal guide and / or the distance between the enclosure and the transceiver device to attenuate electromagnetic interference (EMI) present within the enclosure to the extent that no EMI shielding for the transceiver device is provided other than the original manufacturer housing for the transceiver device. [Brief explanation of the drawings]

[0026] The invention will now be further described, by way of example only, with reference to the accompanying drawings in which: [Figure 1] FIG. 1 is a schematic diagram of a prior art metallurgical furnace. [Figure 2] FIG. 2 is a partial cross-sectional schematic view of a first exemplary embodiment of an electric furnace. [Figure 3] FIG. 3 is a similar view showing a second exemplary embodiment of the furnace. [Figure 4] FIG. 4 is another similar view showing a third exemplary embodiment of the furnace. [Figure 5] FIG. 5 is a schematic diagram of a material feed assembly of a furnace that includes or houses an antenna. DETAILED DESCRIPTION OF THE INVENTION

[0027] A first exemplary embodiment of an electric furnace is generally designated 10 in FIGS.

[0028] The electric furnace 10 includes a vessel 12 having a base 14, at least one sidewall 16, and a roof 18 in the roof region of the furnace. The vessel has a central axis 19 extending between the roof and the base. The vessel defines a chamber 21 that holds material 20 to be treated. At least one electrode 23 extends through the roof toward the material. The material includes at least one layer, such as a top layer 22 of feed material having an upper surface 24. The upper surface is defined by an upper level l u and the lower level l lThe furnace 10 further includes at least one non-contact sensor 30.1 and 30.2 for detecting a distance 32 between a reference point (such as point 34) and a position on the top surface 24. The at least one non-contact sensor 30.1 includes an electromagnetic signal transmitter 36, an electromagnetic signal receiver 38, an emitter 40 spaced above the top surface 24 for emitting an electromagnetic signal 42 toward the top surface 24, and a collector 40 for receiving a reflection 44 of the emitted signal from the top surface. A signal guide 46 extends between a) the transmitter 36 and the emitter 40 and / or b) the receiver 38 and the collector 40. At least one of the transmitter 36 and the receiver 38 is located a) above the upper level l of the top surface 24. u 2 and 3), or b) above the level l of the upper surface 24. u 4, the layer 22 is spaced apart from the first line 39 extending parallel to the central axis by a distance d0>0 along a second line 41 perpendicular to the central axis at a height greater than d0>0.

[0029] Referring to FIGS. 2-4, at least one non-contact sensor 30.1, 30.2 is connected to a controller 48 for generating data relating to the sensed distance 32.

[0030] At least one feed port 49 for feed material is defined in roof 18. A feed chute (not shown) may be provided in communication with port 49. In some embodiments, a feed assembly or dead box 70 may be provided above or within roof 18, as described in more detail below with reference to FIG.

[0031] The material 20 comprises a charge including molten metal 50, a slag layer 52 on the molten metal, and a layer of feed material 22 on the slag layer. An upper surface 24 extending between the side walls of the vessel extends below a lower level 1. l and upper level l uIt will be appreciated that the furnace has a three-dimensional profile extending between . It will further be appreciated that this profile does not remain static, but is dynamic and changes during use as feed material is added and as processed molten metal, matte, and / or slag is tapped from the furnace.

[0032] Thus, in one exemplary embodiment, a plurality of non-contact sensors 30.1 and 30.2 are provided to monitor the level at a plurality of distributed locations on top surface 24. Each of the non-contact sensors is configured to sense a respective distance between a respective reference point and a respective one of the plurality of distributed locations on top surface 24, and the controller operates to generate profile data regarding top surface 24 from the respective sensed distances.

[0033] The non-contact sensor may be any suitable sensor, but preferably comprises a microwave radar sensor, such as those sold under the trade names VEGA or Siemens. The radar sensor comprises a radar transceiver 36, 38 housed in an original manufacturer (“OM”) housing 54. The transceiver 36, 38 comprises a transmitter 36 and a receiver 38.

[0034] The emitter and collector may be embodied in a horn antenna 40. The horn antenna 40 is mounted in a suitable location in the roof area, such as below the roof 18 (not shown), within a passage defined in the roof 18 (not shown), or above the passage as shown in Figures 2-4.

[0035] The horn antenna 40 may be mounted within a chamber 60 defined by a riser 62 attached to a penetration 64 in the roof 18. The chamber 60 may be in communication with a supply conduit 66 for a suitable cooling fluid to cool the exterior surface of the horn antenna.

[0036] A waveguide 46, one end fixed to the housing 54 and the other end fixed to the horn antenna, connects the transceiver to the horn antenna and directs the electromagnetic signal 42 from the transmitter 36 of the transceiver to the horn antenna, where it is emitted towards the surface 24. Reflections 44 are collected by the horn antenna and directed by the waveguide 46 to the receiver 38 of the transceiver. As shown in Figure 4, an inlet 68 for a suitable cooling fluid may be provided in the waveguide 46 to cool the horn antenna from the inside.

[0037] As shown in Figures 2 and 3, the transceivers 36, 38 may be located outside the container adjacent at least one sidewall 16 or an exterior surface of the base 14 of the container 12. The transceivers 36, 38 may be located at any suitable distance d1 from the container. The transceivers 36, 38 may be located directly adjacent to a sidewall (not shown) or may be spaced apart from the sidewall as shown in Figures 2 and 3. In Figure 2, the transceivers 36, 38 are located at an upper level l of the top surface 24. u 3, the transmitter and receiver devices 36, 38 are located at an upper level l of the upper surface 24. u and the lower level l l It is located at a height between

[0038] It will be appreciated that the waveguide 46 must have the necessary length to connect the transmitting and receiving devices 36, 38 in the locations referred to above to the horn antenna 40 in the roof area of ​​the vessel.

[0039] Another exemplary embodiment of the electric furnace 10 is shown in Figure 4. In this embodiment, a transceiver system including a transmitter 36 and a receiver 38 housed in an original manufacturer housing 54 is located above the upper level 1 of the top surface 24. u At any height relative to the layer 22, including heights higher than 1000 mm, the transmitter / receiver devices 36, 38 are located outside a first line 39 extending parallel to the central axis 19, spaced a distance d0>0 from the layer along a second line 41 perpendicular to the central axis 19. In this particular embodiment, the transmitter / receiver devices 36, 38 may be located at a height several meters higher than the roof 18.

[0040] Electromagnetic interference (EMI) above layer 22 within the furnace, primarily emanating from electrodes 23 energized at 50 Hz, is sufficiently attenuated by side walls 16 and distance (due to the inverse square law) to the extent that no special EMI shielding is required for the radar transmitter / receiver 36, 38 or other parts of non-contact sensor 30 within the original manufacturer's housing 54.

[0041] 5 illustrates an exemplary embodiment of a feed assembly 70. The assembly includes a box 72 having an inlet 74 for the feed material defined in its top wall and an outlet 76 for the feed material defined in its bottom wall. The outlet 76 is linearly offset relative to the inlet 74. Thus, a curved flow path 78 for the feed material extends between the inlet 74 and the outlet 76. The horn antenna 40 is mounted in or on the box directly above the outlet 76, thereby providing a direct line of sight through the outlet and a straight path through the outlet 76 for the signal 42 and reflections 44 between the antenna 40 and the top surface 24.

[0042] A heat shielding system 80 may be provided to protect the antenna 40 from radiant heat generated by processing within the furnace. The shielding system may include a selectively openable shutter 82 between the antenna and the outlet 76 (and thus the processing), and, optionally, a sidewall 84 between the antenna 40 and the flow path 78. The shutter 82 may be in the form of a "slide gate" or flap that may be selectively controlled by at least one of a manual, electric, hydraulic, or pneumatic control device 86.

Claims

1. at least one electrode; A vessel having a base, at least one sidewall, and a roof area including a roof, for holding material to be processed, the vessel having a central axis extending between the roof and the base, the material being at an upper level (l u ) and the lower level (l l a container including at least one layer having a top surface having a roof and a base, the at least one electrode extending through the roof and into the container; At least one non-contact sensor for detecting a distance between a reference point and a position on the top surface, the non-contact sensor comprising: an electromagnetic signal transmitter; an electromagnetic signal receiver; a emitter for emitting an electromagnetic signal toward the top surface, the emitter being located in the roof area at a distance above the top surface; a collector for reflecting the emitted signal from the top surface; and a signal guide at least one of a) between the transmitter and the emitter and b) between the receiver and the collector, wherein at least one of the transmitter and the receiver is located outside the container at a) an upper level (l) of the top surface. u ) or b) located at a height lower than the upper level (l u ) at a height greater than the center axis, a distance d from the layer along a second line perpendicular to the center axis 0 and a non-contact sensor located outside a first line extending parallel to the central axis and spaced apart by a distance >0, wherein at least one of the transmitter and the receiver is positioned in a location where electromagnetic interference (EMI) from inside the vessel is sufficiently attenuated so that at least one of the transmitter and the receiver can operate without EMI shielding other than an original manufacturer housing.

2. 2. The furnace of claim 1, wherein the layer is a top layer of feed material.

3. 3. The furnace of claim 1, wherein the at least one non-contact sensor is connected to a controller for generating data regarding the sensed distance.

4. 4. The furnace of claim 3, comprising a plurality of said non-contact sensors connected to said controller, each said non-contact sensor for detecting a respective distance between a respective reference point and a respective one of a plurality of distributed locations on said upper surface, said controller operative to generate profile data relating to said upper surface from each detected distance.

5. 2. The furnace of claim 1, wherein the transmitter and receiver are located at an elevation below an upper level of the top surface.

6. 2. The furnace of claim 1, wherein the transmitter and receiver are located at an elevation between an upper level and a lower level of the top surface.

7. 7. The furnace of claim 5, wherein the transmitter and receiver are located adjacent an exterior surface of the at least one sidewall of the vessel.

8. 7. The furnace of claim 5, wherein the transmitter and receiver are located remotely from the vessel.

9. 2. The furnace of claim 1, wherein the transmitter and receiver are located at an elevation above an upper level of the top surface.

10. 10. The furnace of claim 1, wherein the at least one non-contact sensor comprises any one of a laser sensor, an automatic bathymetry sensor, an acoustic sensor, an optical sensor, a muon particle sensor, a pulsed or frequency modulated electromagnetic sensor, an ultrasonic sensor, and a yo-yo sensor.

11. The furnace of claim 1 , wherein the at least one non-contact sensor comprises a radar sensor.

12. 12. The furnace of claim 11, wherein the radar sensor comprises a microwave radar transmitter / receiver, an antenna acting as the emitter and the collector, and a waveguide connecting the transmitter / receiver to the antenna.

13. 13. The furnace of claim 12, wherein the antenna is a horn antenna.

14. 2. The furnace of claim 1, further comprising a material feed arrangement at a feed port formed in the roof, the material feed arrangement comprising a box having an inlet for feed material defined in a top wall and an outlet for feed material defined in a bottom wall, the inlet being linearly offset from the outlet, the launcher and collector being aligned with the outlet to provide a line of sight through the outlet.

15. at least one electrode; a vessel for holding a material to be treated, the vessel comprising a base, at least one sidewall, and a roof region including a roof, the material including at least one layer having a top surface, the at least one electrode extending through the roof and into the vessel; and at least one non-contact sensor for detecting a distance between a reference point and a location on the top surface, the non-contact sensor comprising: an electromagnetic signal transmitting / receiving device; an antenna located in the roof area spaced above the top surface; and a signal guide extending between the electromagnetic signal transmitting / receiving device and the antenna, the transmitting / receiving device being located outside the vessel at a predetermined location where at least one of the vessel and the distance attenuates electromagnetic interference (EMI) within the vessel to an extent that no EMI shielding for the transmitting / receiving device other than an original manufacturer's housing for the transmitting / receiving device is required.

16. A method for operating an electric furnace according to claim 15, comprising: disposing the transceiver device outside the container; and utilizing the signal guide and / or the distance between the enclosure and the transceiver device to attenuate electromagnetic interference (EMI) present within the enclosure to a degree that the transceiver device requires no EMI shielding for the transceiver device other than the original manufacturer housing for the transceiver device.

Images