Fall prevention device in electrostatic precipitator

Abstract

To provide an electric dust collector which does not exert a bad influence on a conveyor installed at the bottom part of the electric dust collector even when a hammering device arranged in the electric dust collector or a portion to be stricken by the hammering device falls down.SOLUTION: A fall prevention device in an electric dust collector prevents, when falling a component of a hammering device 20 installed in the electric dust collector 1, or a component of stricken parts of a plurality of discharge electrodes 12 and a plurality of dust collecting electrodes 11 stricken by the hammering device 20 falls down, the component from falling to the bottom of the electric dust collector 1. The fall prevention device in the electric dust collector comprises: a net-like body 30 which is installed below the stricken part; and powder removal means which removes powder stacked on the net-like body 30.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fall prevention device provided in an electric dust collector, and in particular to a fall prevention device provided to prevent a hammering device or its struck part provided in the electric dust collector from falling off and adversely affecting the conveying means at the bottom of the electric dust collector. [Background technology]

[0002] In various furnaces such as rotary kilns in metal smelting plants, dry processing is carried out to improve the grade of the target metal by subjecting metal raw materials to reduction treatment, etc. In this dry processing, exhaust gas containing aerosols such as dust and mist (hereinafter collectively referred to as dust, etc.) is discharged, so that before subjecting this exhaust gas to gas treatment such as detoxification treatment according to its composition, a dust removal process is generally carried out in which the exhaust gas is first introduced into a dust collection facility to remove dust, etc.

[0003] In the above dust collection equipment, one or more pieces of equipment are selected depending on the amount of exhaust gas to be treated and the physical properties of the dust contained therein from among bag filters that remove dust by filtering through a bag-shaped filter, cyclones that remove dust by using centrifugal force, wet dust collectors that remove dust by passing the exhaust gas through water or spraying water on it, and electric dust collectors that remove dust by applying an electric force generated by applying a high DC voltage between a parallel plate-shaped or similar dust collecting electrode and a metal wire-shaped discharge electrode, etc. Of these, electric dust collectors are generally used in metal smelting plants because they can efficiently separate and remove dust with low pressure loss from large volumes of exhaust gas.

[0004] In the above-mentioned electrostatic precipitators, in order to prevent the dust collection performance from decreasing, it is necessary to periodically remove particles such as dust adhering to the dust collecting electrode. In this case, there are two types of electrostatic precipitators: a dry type that collects the dust to be collected contained in the exhaust gas on a dust collecting plate while it is still dry, and a wet type that sprays water onto the surface of the dust collecting electrode to wash away the particles adhering to the dust collecting electrode together with the water. In the latter wet type electrostatic precipitator, dust adhering to the dust collecting electrode can be removed by spraying water onto it, but in the former dry type electrostatic precipitator, dust adhering to the dust collecting electrode cannot be removed using water.

[0005] Therefore, in dry-type electrostatic precipitators, a method is adopted in which dust and the like adhering to the dust collecting electrode is peeled off by striking the collecting electrode with a hammering part of a rotary hammering device (sometimes called a hammering device), as disclosed in, for example, Patent Document 1. Also, since dust and the like gradually adheres to the discharge electrode as operation continues, a method is adopted in which the end of a member suspending the discharge electrode is struck with a hammering part of a rotary hammering device in the same manner as above, thereby peeling off the dust and the like adhering to the discharge electrode. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2015-085264 A Summary of the Invention [Problem to be solved by the invention]

[0007] The hammering device used inside an electric dust collector may be used in an exhaust gas atmosphere containing a high concentration of dust, etc. In this case, the hammering part of the hammering device and the part struck by the hammering part are subjected to repeated impacts during striking and are constantly used under severe wear conditions. Furthermore, exhaust gas is generally at high temperature and often contains corrosive gas components such as chlorine, fluorine, and sulfurous acid gas, so in this case they are exposed to a severely corrosive atmosphere.

[0008] For this reason, the hammering part of the hammering device and the part struck by it often fall off due to wear and cracking, and become caught in the powder discharge conveyor installed at the bottom of the electrostatic precipitator, causing frequent troubles such as stopping the operation of the conveyor. When the operation of the conveyor stops in this way, it becomes necessary to stop the operation of the dust collection equipment in order to restore it, and further, it becomes necessary to stop the operation of the plant that is the source of the exhaust gas, which has a serious adverse effect on the availability rate of the plant.

[0009] The present invention has been made in consideration of the problems associated with the conventional electric dust collectors described above, and has as its object to provide an electric dust collector which does not adversely affect the conveyor provided at the bottom of the electric dust collector, even if the hammering device provided within the electric dust collector or the part struck by the hammering device falls off. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the fall prevention device in an electric dust collector of the present invention is a fall prevention device that prevents components of a hammering device provided in the electric dust collector and components of the struck parts of a plurality of discharge electrodes or a plurality of dust collecting electrodes struck by the hammering device from falling to the bottom of the electric dust collector when these components fall off, and is characterized in that it comprises a mesh body provided below the struck parts, and powder removal means for removing powder accumulated on the mesh body. Effect of the Invention

[0011] According to the present invention, even if a component of a hammering device provided inside an electric dust collector or a component of a part struck by the hammering device falls off, it is possible to prevent adverse effects on the conveyor provided at the bottom of the electric dust collector. [Brief description of the drawings]

[0012] [Figure 1] 1 is a partially cutaway perspective view of an electric dust collector to which the fall prevention device of the present invention is preferably provided. [Diagram 2] FIG. 2 is a perspective view of a hammering device provided in the electric dust collector of FIG. [Diagram 3] 3 is a side view of a fall prevention device according to an embodiment of the present invention, which is provided below the hammering portion of the hammering device of FIG. 2 and the portion to be struck by the hammering portion. [Figure 4] 1 is a perspective view showing a specific example of a means for removing accumulated powder provided in a fall prevention device according to an embodiment of the present invention. FIG. [Diagram 5] 13 is a perspective view showing another specific example of a means for removing accumulated powder provided in a fall prevention device according to an embodiment of the present invention. FIG. [Figure 6] 13 is a perspective view showing yet another specific example of the means for removing accumulated powder provided in the fall prevention device of the embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A fall prevention device according to an embodiment of the present invention provided inside an electric dust collector will be described in detail below. An electric dust collector to which a fall prevention device according to an embodiment of the present invention is provided has a structure shown in FIG. 1, for example. Specifically, the electric dust collector 1 shown in FIG. 1 has a structure in which a rectangular plate-shaped dust collecting electrode 11 and a discharge electrode 12 having a group of discharge wires hanging down from a beam-shaped frame are suspended parallel to each other and alternately within a main body 10 having an upper portion having a substantially rectangular parallelepiped shape, and a DC high voltage is applied between the dust collecting electrode 11 and the discharge electrode 12 facing each other by a DC voltage power source (not shown). The discharge wires of the discharge electrode 12 hang down from the beam-shaped frame at equal intervals in the longitudinal direction, and weights are hung from their lower ends.

[0014] A strong electric field is formed between the discharge electrode 12 and the collecting electrode 11 by the applied DC high voltage, and the gas around the discharge electrode 12 is ionized by the corona discharge generated by this. In this state, as shown by the white arrow, when exhaust gas containing dust and the like is introduced from the inlet 10a of the main body 10 and passed through the gas flow path between the collecting electrode 11 and the discharge electrode 12, the particles such as dust contained in the exhaust gas are negatively charged with anions. As a result, the charged particles are collected by the collecting electrode 11 by the Coulomb force of the electric field, and the dust concentration of the exhaust gas discharged from the outlet 10b of the main body 10 can be significantly reduced.

[0015] If the particles adhering to the collecting electrode 11 as described above are left as they are, the dust collection performance will decrease, so the electric dust collector 1 shown in Fig. 1 is provided with a hammering device (also called a hammering device or striking device) 20 that applies an impact force to the collecting electrode 11 to peel off dust and the like. Note that, although only a small number of particles, such as dust, that pass near the discharge electrode 12 become positively charged with cations and are collected by the discharge electrode 12, so a hammering device is often provided on the discharge electrode 12 as well. The hammering device for this discharge electrode 12 has a structure similar to that of the hammering device 20 for the collecting electrode 11, so in order to avoid duplication of explanation, the following explanation will be given by taking up the hammering device 20 for the collecting electrode 11 as a representative.

[0016] The hammering device 20 is, for example, as shown in Fig. 2, composed of a horizontally extending rotary shaft 21 rotatably supported by a support (not shown), a driving unit 22 such as an electric motor that rotates the rotary shaft 21, and a plurality of hammering units 23 provided on the rotary shaft 21 along its axial direction. A driving chain 21b is hung between a sprocket 22a provided on the driving shaft of the driving unit 22 and a sprocket 21a provided on one end of the rotary shaft 21, so that the rotational driving force of the driving unit 22 is transmitted to the rotary shaft 21. Since the driving unit 22 is installed on the outside of the main body 10, one end of the rotary shaft 21 on the side where the sprocket 21a is attached penetrates the side wall of the main body 10 and protrudes to the outside of the main body 10, and an insulator unit 21c is provided on the protruding portion of the rotary shaft 21.

[0017] The multiple hammering parts 23 are provided at equal intervals in the axial direction of the rotating shaft 21 so as to strike, in the extension direction, the rod-shaped struck parts 11a provided at the upper ends of the multiple dust collecting electrodes 11. As shown in Fig. 3, the multiple hammering parts 23 are composed of a rod-shaped part 23a that rotates clockwise in the plane of the drawing together with the rotating shaft 21, a swinging part 23b that is pivotally supported at the tip of the rod-shaped part 23a so as to be swingable about a first support shaft S1 that is parallel to the axial direction of the rotating shaft 21, and a cylindrical hammer part 23c that is pivotally supported at the tip of the swinging part 23b so as to be rotatable about a second support shaft S2 that is parallel to the axial direction of the rotating shaft 21.

[0018] With this configuration, when the rotary shaft 21 rotates via the drive chain 21b by the rotary drive of the drive unit 22, the rod-shaped part 23a also rotates, and the swinging part 23b moves as if it is being pulled up by the rod-shaped part 23a. At this time, since one end of the swinging part 23b is pivotally supported by the tip of the rod-shaped part 23a as described above, the swinging part 23b moves to gradually lift the hammer part 23c as shown by the dashed line in Figure 3, and when the rod-shaped part 23a comes just before the position shown by the solid line, the hammer part 23c passes slightly from the position almost directly above as shown by the dashed line, so that the swinging part 23b loses balance and is swung down with force toward the end of the struck part 11a together with the hammer part 23c. This makes it possible to apply a striking force to the struck part 11a. As shown in FIG. 2, it is preferable that the rod-shaped portions 23a of the plurality of hammering portions 23 are attached so that the directions in which they protrude in the radial direction of the rotating shaft 21 are different from one another.

[0019] The dust and the like peeled off by the impact of the hammering device 20 falls toward the bottom of the main body 10. The opposing side walls constituting the main body 10 are inclined at their lower parts so that the distance between them gradually narrows toward the bottom, and the peeled off dust and the like is collected at the center of the bottom along these inclined surfaces, and is transported to the bottom discharge port 10c by a first transport means 13 such as a flight conveyor provided at the center of the bottom along the flow direction of the exhaust gas, and is discharged from there to the outside as shown by the black arrow. A second transport means 14 such as a flight conveyor is further provided below this bottom discharge port 10c, and the dust and the like discharged from the bottom discharge port 10c is transported to a predetermined destination together with the dust and the like discharged from other adjacent electrostatic precipitators 1.

[0020] Incidentally, the struck portion 11a of the dust collecting electrode 11 is repeatedly struck by the hammering portion 23 of the hammering device 20 as described above by the continuous rotation of the driving portion 22, so that a reinforcing member 11b is attached by welding or the like to the end portion of the struck portion 11a where the hammer portion 23c abuts in order to increase the mechanical strength. Therefore, this reinforcing member 11b may fall off the struck portion 11a due to wear at the welded portion as the hammering portion 23 is repeatedly struck over a long period of time. In addition, the members constituting the hammering portion 23 of the hammering device 20 may also break and fall off during long-term use.

[0021] If the reinforcing member 11b of the struck portion 11a or a component of the hammering portion 23 falls off, it may become caught between the chain and roller of the flight conveyor, which is the first conveying means 13 provided at the bottom of the electrostatic precipitator 1, causing a problem in which the operation of the first conveying means stops. Therefore, in order to avoid such trouble caused by fallen parts, as shown in Figure 3, a fall prevention device consisting of a mesh body 30 and a powder removal means for removing powder accumulated on it is provided below the struck portion 11a of the dust collecting electrode 11.

[0022] This prevents the components of the hammering section 23 and the reinforcing member 11b of the struck section 11a from falling off as shown by the white arrows, and thus prevents them from falling below the mesh body 30. In addition, since a powder removal means is provided, it is possible to prevent the mesh body 30 from falling off due to the load of dust and the like accumulated on the mesh body 30, and from adversely affecting the conveyor and the like at the bottom of the main body 10. In this way, by normally preventing as much load as possible from being applied to the mesh body 30, the mesh body 30 can be prevented from falling off due to the load of dust and the like accumulated on the mesh body 30, and from adversely affecting the conveyor and the like at the bottom of the main body 10. 3 Even in an electrostatic precipitator that processes exhaust gas with a high dust concentration as described above, the above-mentioned falling off of the mesh body 30 and problems resulting from this can be prevented.

[0023] The above-mentioned mesh body 30 preferably extends from one end to the other in the width direction of the main body 10 so that it can capture any reinforcing member 11b of the multiple struck parts 11a that falls off, or any component of the multiple hammering parts 23 that strike the multiple struck parts 11a that fall off. For this reason, it is preferable to support both ends of the mesh body 30 in the width direction by two horizontal support rods 31 that extend in the width direction of the main body 10 and are spaced apart from each other in the horizontal direction.

[0024] In this case, the vertical distance D from the lowest part of the struck part 11a and the hammering part 23 to the mesh body 30 is preferably within a range of 100 to 500 mm. Also, the horizontal distance W between the two horizontal support rods 31 is preferably within a range of 300 to 600 mm. This allows the mesh body 30 to be installed without particularly impeding the flow of exhaust gas even in the main body 10, which generally has a small space.

[0025] The mesh body 30 and its horizontal support rods 31 are preferably made of metal with a heat-resistant temperature of 200° C. or higher, more preferably made of SUS, and most preferably made of SUS304. The wires constituting the mesh body 30 preferably have a wire diameter of 2 mm or less, and the mesh size is preferably 30 mm or more and 70 mm or less. There are no particular limitations on the mesh shape of the mesh body 30, and various shapes such as a lattice shape, a honeycomb shape, a diamond shape, etc. can be used.

[0026] By setting the heat resistance temperature of the mesh body 30 and its horizontal support rods 31 to 200°C or higher as described above, it becomes possible to use the electrostatic precipitator 1 for a long period of time even in a corrosive atmosphere that is prone to wear, as described above. Furthermore, by setting the wire diameter of the wires constituting the mesh body 30 to 2 mm or less and the mesh size to 30 mm or more, it becomes possible to minimize the amount of dust and the like that accumulates on the mesh body 30, and also to prevent the mesh from becoming clogged with dust and the like that has accumulated on the mesh body 30.

[0027] Furthermore, it is more preferable that the wires constituting the net body 30 are in the form of single threads rather than twisted strings. The reason for this is that the surface area of ​​the wires constituting the net body 30 can be reduced by using single threads, which results in further suppression of dust and the like accumulating on the surface of the wires. Also, by making the mesh size of the net body 30 70 mm or less, even if the components of the hammering part 23 or the reinforcing member 11b of the struck part 11a fall off, they can be reliably captured by the net body 30.

[0028] 4, there is a crank mechanism that is configured with a crank arm 40 provided on the rotating shaft 21 and a connecting part 41 made of a metal rod or the like that connects a horizontal support rod 31 that supports the mesh body 30 to the tip of the crank arm 40. With this configuration, the mesh body 30 can be vibrated up and down as the rotating shaft 21 rotates.

[0029] The crank mechanisms are preferably provided on the rotating shaft 21 at positions corresponding to both ends of the horizontal support rod 31 that supports the mesh body 30, but instead of or in addition to these positions, they may be provided at a position corresponding to the midpoint in the longitudinal direction of the mesh body 30. In either case, when crank mechanisms are provided at multiple locations along the longitudinal direction of the mesh body 30, they are preferably provided at equal intervals in the longitudinal direction of the mesh body 30.

[0030] In order to prevent the mesh body 30 from moving around irregularly, for example, support plates for the horizontal support rod 31 may be attached to both inner wall parts facing each other in the width direction of the main body 10, and long holes extending in the vertical direction may be drilled in each support plate, and both ends of the horizontal support rod 31 may be loosely fitted into the long holes to restrict the mesh body 30 to move only in the vertical direction. Also, instead of the crank mechanism, a cam-like member may be provided on the rotating shaft 21, and a protrusion provided on a rod-like body extending upward from the horizontal support rod 31 of the mesh body 30 may be engaged with the cam-like member to vibrate the mesh body 30 in the vertical direction. In this case, one end of a spring may be fixed and the other end may be attached to the horizontal support rod 31 of the mesh body 30 so that the mesh body 30 is always biased downward.

[0031] Another specific example of the powder removing means for removing the powder accumulated on the mesh body 30 is a compressed air injection device, as shown in FIG. 5, which is composed of a pipe 50 extending parallel to the mesh body 30 and having a plurality of openings 51 opening toward the mesh body 30, and an air supply device such as an air compressor for supplying compressed air into the pipe 50. When the compressed air is injected from the openings 51 of the pipe 50, it is preferable to inject it in a pulsed manner, which can be realized, for example, by providing an electromagnetic valve in the air supply pipe connecting the air compressor and the pipe 50 and automatically opening and closing the electromagnetic valve using a timer or the like. This can reduce the operating cost of the air compressor. When a compressed air injection device is used as the powder removing means as described above, it is preferable to fix both ends of the horizontal support bar 31 to both inner wall portions facing each other in the width direction of the main body 10.

[0032] As another specific example of the removing means for removing the powder accumulated on the net-like body 30, there can be mentioned a vibration device 60 provided at one end of a horizontal support rod 31 supporting the net-like body 30, as shown in FIG. 6(a). For this vibration device 60, for example, a structure in which a weight is eccentrically attached to the drive shaft of an electric motor can be suitably used. When an electric motor is used for the vibration device 60, it is necessary to install the vibration device 60 outside the main body 10, so it is preferable to attach a base 61 to the outer wall of the main body 10 and fix the end of the horizontal support rod 31 penetrating the vibration device 60 and the side wall of the main body 10 on the surface of the base 61. The horizontal support rod 31 of the net-like body 30 may be supported by a vertical support rod 32 hanging down from the ceiling of the main body 10. In this case, the vibration device 60 is attached to the end of the vertical support rod 32 penetrating the ceiling of the main body 10 via the base 61, as shown in FIG. 6(b). EXAMPLES

[0033] Exhaust gas containing crude zinc oxide dust discharged from a rotary kiln in which crude zinc oxide is produced by reducing and roasting steelmaking dust using the Weltz kiln method was introduced into an electrostatic precipitator 1 as shown in Fig. 1 for dust removal. A hammering device 20 as shown in Fig. 2 was provided on a plurality of dust collecting electrodes 11 in this electrostatic precipitator 1, and an internal fall prevention device according to an embodiment of the present invention was provided below the hammering device as shown in Fig. 3.

[0034] Specifically, the fall prevention device of this embodiment uses a mesh body 30 made of a metal net woven in a lattice pattern with 70 mm mesh openings from monofilamentary metal wires made of SUS304 with a wire diameter of 2 mm, and both ends in the width direction of the mesh body 30 are wound around two horizontal support rods 31 made of SUS304 with a wire diameter of 5 mm, respectively, and both ends of each of these two horizontal support rods 31 are attached to the inner wall of the main body 10, thereby stretching the mesh body 30 from one end to the other in the width direction of the main body 10 of the electric dust collector 1. At this time, the vertical separation distance D from the lowest positions of the struck part 11a of the dust collecting electrode 11 and the hammering part 23 of the hammering device 20 to the mesh body 30 was set to 500 mm, and the horizontal separation distance W between the two horizontal support rods 31 was set to 600 mm.

[0035] As shown in Fig. 5, a pipe 50 with a nominal diameter of 25A was installed in parallel to the longitudinal direction of the mesh body 30 and extending from one end to the other in the longitudinal direction of the mesh body 30 as a powder removal means for removing the powder accumulated on the mesh body 30. This pipe 50 was provided with openings 51 with an inner diameter of 5 mm at intervals of 200 mm so that compressed air could be blown toward the mesh body 30. An air compressor was connected to one end of the pipe 50 via an air supply pipe, and a solenoid valve was provided on the air supply pipe so that the solenoid valve was opened once every 10 minutes.

[0036] In this state, the above exhaust gas is pumped at a flow rate of 50,000 Nm 3 / hr, dust concentration at the inlet 10a of the main body 10 of the electrostatic precipitator 1 is 80.0 g / Nm 3 , dust concentration at outlet 10b is 3.0 g / Nm 3 The electrostatic precipitator 1 was operated for six months under the condition that the exhaust gas temperature at the inlet 10a of the main body 10 was 300° C. or less. As a result, the reinforcing member 11b provided at the contact portion of the struck portion 11a of the dust collecting electrode 11 fell off six times during the six months, but all of the falling off occurred in the mesh body 30.

[0037] For comparison, an operation was carried out for six months under the same conditions as in the above embodiment, except that the fall prevention device was not adopted. As a result, the reinforcing member 11b provided at the contact portion of the struck portion 11a of the dust collecting electrode 11 fell off six times during the six months, and in two of those cases, the fallen part was able to be recovered when it was discharged from the conveyor, but in the remaining four cases, it got caught in the conveyor provided at the bottom of the electrostatic precipitator, and operation had to be suddenly stopped. [Explanation of symbols]

[0038] 1. Electrostatic precipitator 10. Main Unit 10a entrance 10b exit 10c bottom outlet 11 Dust collecting pole 11a Hit part 11b Reinforcing member 12 Discharge electrode 13 First conveying means 14 Second conveying means 20 Hammering device 21 Rotation axis 21a sprocket 21b Drive chain 21c Insulator section 22 Drive unit 22a sprocket 23 Hammering Department 23a Rod-shaped part 23b Swinging part 23c Hammer section 30 Reticulum 31 Horizontal support rod 32 Vertical support rod 40 Crank arm 41 Connecting part 50 Pipe 51 Opening 60 Vibration device 61 Foundation S1 1st spindle S2 2nd spindle

Claims

1. A fall prevention device that prevents components of a hammering device provided in an electric dust collector and components of the struck parts of a plurality of discharge electrodes or a plurality of dust collecting electrodes struck by the hammering device from falling to the bottom of the electric dust collector when the components fall off, the fall prevention device comprising a mesh body provided below the struck parts and a powder removal means for removing powder accumulated on the mesh body.

2. A fall prevention device as described in claim 1, characterized in that the powder removal means is a crank mechanism consisting of a crank arm provided on a rotating shaft constituting the hammering device and a connecting portion that connects a support rod supporting the mesh body to the tip of the crank arm.

3. 2. A fall prevention device as described in claim 1, characterized in that the powder removal means comprises a pipe extending parallel to the mesh body and having a plurality of openings opening toward the mesh body, and a device for supplying compressed air into the pipe.

4. 2. The fall prevention device according to claim 1, wherein the powder removing means is a vibration device provided at one end of a support rod supporting the net-like body.

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