Electrostatic precipitator clogging detection device, exhaust gas treatment device, and cement manufacturing equipment

Abstract

This device reliably detects blockages in electrostatic precipitators with a simple design, enabling smooth exhaust gas processing. [Solution] An electrostatic precipitator having an electrostatic precipitator body connected to an exhaust gas passage and a hopper installed at the bottom of the electrostatic precipitator body, the device for detecting blockage in the hopper comprises a detection tube installed in the hopper, a blower that supplies gas to the detection tube, a branch tube branched from the detection tube with its tip pointed upward, a floating body provided at the tip of the branch tube that rises due to the pressure inside the branch tube, a detection switch activated by the floating body, and a blockage alarm that notifies the operation of the detection switch.

Description

Technical Field

[0001] The present invention relates to a clogging detection device for an electrostatic precipitator used in an exhaust gas treatment device such as a cement manufacturing facility, an exhaust gas treatment device using the clogging detection device, and a cement manufacturing facility having the exhaust gas treatment device.

Background Art

[0002] In an exhaust gas treatment device of a cement manufacturing facility, the generated exhaust gas is passed through an electrostatic precipitator and then exhausted. The dust collected by this electrostatic precipitator is discharged from the lower hopper through a conveyance path. However, if the hopper becomes clogged due to excessive moisture or the like, it may cause sparks or poor charging.

[0003] Therefore, Patent Document 1 discloses a technique of injecting gas from a nozzle to a position where dust is likely to accumulate in a hopper to remove the deposited matter. Specifically, in a dry electrostatic precipitator, a nozzle for gas injection is arranged at the dust deposition position of the lower hopper that collects the dust of the dust collecting electrode, and gas is injected from this nozzle toward the dust deposition position to prevent dust deposition. It is described that the gas injection from the nozzle is performed, for example, periodically.

[0004] Further, in Patent Document 2, a balance bar with a hopper is attached to a lifting base through an elastic body, and the other end of the balance bar is formed to protrude from the end of the lifting base, and the displacement of the other end of the balance bar is detected through a displacement detection device to detect clogging of the hopper. That is, when clogging occurs in the hopper, the weight of the entire hopper increases, so the balance bar is displaced, and this displacement is detected. As the displacement detection device, there are those that detect the displacement of the hopper by a limit switch, those that install a reflection type photoelectric switch having a light emitting part and a light receiving part at the upper part of the hopper and determine clogging by the amount of light received by the light receiving part, and those that attach a strain gauge to the balance bar and determine clogging of the hopper by the amount of strain of this strain gauge.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-323050 [Patent Document 2] Japanese Patent Application Publication No. 8-48312 [Overview of the project] [Problems that the invention aims to solve]

[0006] The technology described in Patent Document 1 is a technique for removing sediment and cannot detect the occurrence of blockages. Furthermore, the technology described in Patent Document 2 detects blockages from changes in the total weight of a heavy hopper, which may lead to false detections, and a more accurate detection method is desired.

[0007] This invention has been made in view of these circumstances, and aims to reliably detect blockages in an electrostatic precipitator with a simple configuration and to smoothly process exhaust gas. [Means for solving the problem]

[0008] The present invention relates to an electrostatic precipitator clogging detection device, which is a device for detecting clogging in a hopper in an electrostatic precipitator having an electrostatic precipitator body connected to an exhaust gas passage and a hopper installed at the lower part of the electrostatic precipitator body, and comprises a detection tube installed in the hopper, a blower that supplies gas to the detection tube, a branch tube branched from the detection tube with its tip pointed upward, a floating body provided at the tip of the branch tube that rises due to the pressure inside the branch tube, a detection switch operated by the floating body, and a clogging alarm that notifies the operation of the detection switch.

[0009] In this electrostatic precipitator's blockage detection device, when a blockage occurs in the hopper, the supply of gas from the detection tube to the hopper is obstructed, causing the pressure in the detection tube and branch tube to rise. As a result, a float located at the end of the branch tube rises due to the pressure inside the branch tube, activating the detection switch, and the blockage alarm can then notify the user of the blockage.

[0010] In the electrostatic precipitator clogging detection device of the present invention, it is preferable that a shut-off valve is provided between the branching point of the detection pipe and the branch pipe and the tip of the detection pipe. By closing the shut-off valve, the pressure in the branch pipe increases, causing the float to activate the detection switch. Therefore, by periodically or arbitrarily closing the shut-off valve, the activation of the detection switch can be detected.

[0011] In the electrostatic precipitator clogging detection device of the present invention, a plurality of detection tubes connected to the blower are installed in the hopper, and a branch pipe is provided for each detection tube. Since multiple detection tubes are placed inside the hopper, partial blockages inside the hopper can be detected early, and the location of the blockage can also be detected depending on the position of the detection tube.

[0012] In the clogging detection device for an electrostatic precipitator of the present invention, a flow meter may be provided in the detection tube. By detecting the flow rate in the detection pipe using a flow meter, it is possible to predict the occurrence of blockages, enabling a quick response.

[0013] Furthermore, the present invention relates to an exhaust gas treatment device that includes any of the aforementioned electrostatic precipitator clogging detection devices.

[0014] In the exhaust gas treatment apparatus of the present invention, two or more electrostatic precipitators are provided, and the electrostatic precipitators are equipped with the detection pipe connected to the blower, the branch pipe, the float, and the detection switch, and the exhaust gas passage is provided with a switching valve that can switch the flow path to one of the electrostatic precipitators.

[0015] If a blockage is detected, the flow of exhaust gas to that electrostatic precipitator is shut off, and the system switches to another electrostatic precipitator. This allows for continuous exhaust gas treatment while simultaneously performing repair work on the blocked electrostatic precipitator.

[0016] And the present invention is a cement manufacturing facility provided with the exhaust gas treatment device, and it can be assumed that the exhaust gas passage allows the exhaust gas generated in the cement kiln to flow through.

Advantages of the Invention

[0017] According to the present invention, by supplying the description to the detection pipe provided in the hopper of the electrostatic precipitator and detecting the clogging via the branch pipe, it is possible to surely detect the clogging with a simple configuration and smoothly process the exhaust gas.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram showing a cement manufacturing facility according to an embodiment of the present invention. [Figure 2] It is a schematic diagram showing a clogging detection device for an electrostatic precipitator in the cement manufacturing facility of FIG. 1. [Figure 3] It is a schematic diagram near the detection switch in FIG. 2, where (a) shows the normal state and (b) shows the state when clogging occurs. [Figure 4] It is a schematic diagram similar to FIG. 2 showing another example of the clogging detection device for an electrostatic precipitator. [Figure 5] It is a schematic diagram similar to FIG. 2 showing still another example of the clogging detection device for an electrostatic precipitator. [Figure 6] It is a schematic diagram showing an example in which a plurality of detection pipes are provided in one electrostatic precipitator. [Figure 7] It is a schematic diagram showing a group of detection switches at the tip of the branch pipe from a plurality of detection pipes. [Figure 8] It is a schematic diagram showing a main part of an exhaust gas treatment device provided with detection pipes in two electrostatic precipitators.

Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0020] Figure 1 shows an example of cement manufacturing equipment. This cement manufacturing equipment 1 includes a raw material storage facility 2 for individually storing raw materials such as limestone, clay, silica, and iron as cement raw materials; a raw material mill and dryer 3 for crushing and drying these cement raw materials; a preheater 4 for preheating the powdered cement raw materials obtained from the raw material mill; a cement kiln 5 for firing the cement raw materials preheated by the preheater 4; and a clinker cooler 6 for cooling the cement clinker after it has been fired in the cement kiln 5.

[0021] The cement kiln 5 is a cylindrical rotary kiln that is oriented horizontally and slightly inclined downwards from the kiln tail 7 to the kiln front 8, and rotates around its axis. The cement raw materials in the raw material storage room 2 are crushed and dried in the raw material mill and dryer 3, and then sent to the preheater 4 to be preheated before being supplied to the kiln end 7 of the cement kiln 5. In the cement kiln 5, the cement raw materials supplied to the kiln end 7 are sent to the kiln front 8, and during this process, they are heated and fired to approximately 1450°C by the burner 9 at the kiln front 8 to produce cement clinker. This cement clinker is then sent from the kiln front 8 to the clinker cooler 6. After the cement clinker is cooled to a predetermined temperature in the clinker cooler 6, it is sent to the finishing process. In Figure 1, reference numeral 10 indicates a calcination furnace.

[0022] Meanwhile, the exhaust gas generated in the cement kiln 5 passes through the preheater 4 from bottom to top before being introduced into the raw material mill and dryer 3. The raw material mill and dryer 3 simultaneously crush and dry the cement raw materials by receiving the exhaust gas from the cement kiln 5. The exhaust gas from the raw material mill and dryer 3 is then released into the atmosphere through the chimney 11 via the electrostatic precipitator 21, as indicated by the arrow in Figure 1.

[0023] In this embodiment, the exhaust gas passage 22 refers to the passage from the dryer 3 to the electrostatic precipitator 21, and the exhaust gas treatment device 20 refers to a series of devices that release the exhaust gas from the exhaust gas passage 22 through the electrostatic precipitator 21 to the atmosphere.

[0024] To describe the electrostatic precipitator 21 in detail, as shown in Figure 2, this electrostatic precipitator has an electrostatic precipitator body 23 to which exhaust gas passages 22 from the raw material mill and dryer 3 are connected, and a hopper 24 installed at the bottom of the electrostatic precipitator body 23. The electrostatic precipitator body 23 is equipped with a charging unit that charges dust in the exhaust gas to a negative charge, and a dust collection unit (neither of which is shown) that has a discharge electrode and a dust collection electrode. The dust is charged in the charging unit, and a high voltage is applied between the discharge electrode and the dust collection electrode of the dust collection unit to collect the dust at the dust collection electrode. The dust collected in the dust collection unit is then shaken off into the hopper 24 by vibration and transported to the outside through a transport path 25 below the hopper 24.

[0025] In this embodiment, the hopper 24 of the electrostatic precipitator 21 is equipped with a clogging detection device 31. The clogging detection device 31 includes a detection tube 32 installed inside the hopper 24, a blower 33 that supplies gas to the detection tube 32, a branch tube 34 that branches off from the detection tube 32 and whose tip is pointed upward, a float 35 provided at the tip of the branch tube 34 and which rises due to the pressure inside the branch tube 34, a detection switch 36 that is activated by the float tube 35, and a clogging alarm 37 that notifies the operation of the detection switch 36. Reference numeral 38 indicates a control unit that receives a detection signal from the detection switch 36 and controls the operation of the clogging alarm 37, and is configured by a computer.

[0026] The detection tube 32 has its tip positioned at a location in the hopper 24 where clogging is likely to occur, and a gas such as air is supplied from the blower 33 via the gas supply passage 39. The branch pipe 34 branches off from the detection tube 32 midway, and its tip 34a is held vertically. In the illustrated example, the tip 34a of the detection tube 32 is made up of a vertical cylindrical section, as shown in Figure 3, and a spherical float 35 is housed inside this cylindrical section (the tip of the branch pipe 34) 34a. The inner diameter of the cylindrical section 34a is larger than the outer diameter of the float 35, and it is formed so that the float 35 can move freely along its length.

[0027] However, a ring portion 41 with a smaller inner diameter is integrally formed at the tip, and this ring portion 41 forms an opening 42. The inner diameter of this ring portion 41 (the inner diameter of the opening 42) is formed to be slightly smaller than the outer diameter of the float 35, so that a part of the float 35 can protrude from the opening 42, but the ring portion 41 prevents the entire float 35 from flying out of the opening 42.

[0028] A detection switch 36 is provided above the cylindrical portion 34a. In other words, under normal conditions (when the electrostatic precipitator 21 is operating normally), the air supplied from the blower 33 branches and flows through both the detection pipe 32 and the branch pipe 34, so the pressure inside the branch pipe 34 is relatively low. For this reason, near the floating body 35, as shown by the dashed arrow in Figure 3(a), the air passes between the outer surface of the floating body 35 and the inner surface of the cylindrical portion 34a and is released to the outside through the opening 42. Because the pressure of the gas sent to the branch pipe 34 is low, the floating body 35 floats at an intermediate position in the cylindrical portion 34a and does not protrude from the opening 42.

[0029] When the tip of the detection tube 32 becomes clogged with dust, air from the blower 33 does not flow into the detection tube 32, or only a small amount flows, and all or most of it flows into the branch pipe 34. As a result, the pressure inside the branch pipe 34 increases, and the float 35 floats up due to this pressure. As shown in Figure 3(b), it comes into contact with the ring portion 41, which has an inner diameter smaller than the outer diameter of the float 35, and is held in a state where a part of the float 35 protrudes from the opening 42. The detection switch 36 is positioned to be activated when the float 35 protrudes from the opening 42.

[0030] This detection switch 36 is a limit switch that is normally OFF, but is activated when the switch part 36a is pressed from below by the floating body 35, and is connected to the blockage alarm 37. The blockage alarm 37, for example, lights up a lamp to indicate a blockage when the detection switch 36 is turned ON.

[0031] Thus, this blockage detection device 31 has a simple structure in which it supplies gas to the detection pipe 32 and the branch pipe 34, and when a blockage occurs in the detection pipe 32, the pressure rise in the branch pipe 34 raises the float 35 and activates the detection switch 36, thus reliably detecting the occurrence of a blockage. The float 35 is set to have a weight and volume such that it does not protrude from the opening 42 due to the pressure inside the branch pipe 34 under normal conditions (when there is no blockage in the detection pipe 32), but when a blockage occurs, it comes into contact with the ring portion 41 and protrudes from the opening 42 due to the pressure inside the branch pipe 34.

[0032] Figure 4 shows another example of a blockage detection device, in which a shut-off valve 46 is provided in the detection pipe 32. This shut-off valve 46 is located downstream of the branching point 32a with the branch pipe 34 in the detection pipe 32, and is opened and closed manually or by electric power. This shut-off valve 46 is normally set to be open and does not obstruct the flow of gas from the blower 33 to the tip of the detection tube 32. However, if it is closed, the gas from the blower 33 does not flow into the detection tube 32, and the entire amount flows into the branch pipe 34. As a result, the float 35 is pushed up at the cylindrical part 34a at the tip of the branch pipe 34, and the detection switch 36 is activated.

[0033] In other words, closing the shut-off valve 46 activates the detection switch 36. Therefore, if the detection switch 36 does not activate even when the shut-off valve 46 is closed, it is possible that either air from the blower 33 is not being supplied to the branch pipe 34, or that there is a malfunction (blockage or malfunction of the detection switch 36 itself) at some point in the detection mechanism from the branch pipe 34 to the detection switch 36. In that case, an inspection is performed to check whether there is any blockage or other abnormality upstream of the branch pipe 34 or branch section 32a, or whether there is any abnormality in the operation of the detection switch 36, and then the system is restored to its original state.

[0034] By using such a blockage detection device 45, it becomes possible to check for any abnormalities in the blockage detection device 45 itself and take necessary countermeasures by closing the shut-off valve 46 and confirming that the detection switch 36 is functioning correctly. Therefore, by periodically, or arbitrarily as needed, closing the shut-off valve 46 to check the operation of the detection switch 36 and taking countermeasures according to the results, it is possible to maintain the blockage detection device 45, and consequently the electrostatic precipitator 21, in a healthy state and maintain proper exhaust gas treatment.

[0035] Figure 5 shows yet another example of a blockage detection device, in which a flow meter 52 is provided in the detection pipe 32. This flow meter 52 is located downstream of the branch section 32a in the detection pipe 32, and its measured value is sent to the control unit 38 and reported to the alarm 37. In this blockage detection device 45, even if the detection tube 32 is not completely blocked, as blockage begins to occur, the flow rate of gas flowing through the detection tube 32 decreases accordingly, causing the measurement value of the flow meter 52 to change. However, since it is not completely blocked, the float 35 at the tip of the branch pipe 34 does not rise to the uppermost end (ring portion 41), and therefore the detection switch 36 is not activated. If the electrostatic precipitator 21 continues to operate in this state, a completely blocked state will eventually occur. Therefore, by monitoring the flow meter 52's readings, it becomes possible to take appropriate measures such as cleaning before a complete blockage occurs.

[0036] In this blockage detection device 51, the notification form of the alarm 37 can be either to display the measured value of the flow meter 52 directly, or to use only an indicator lamp and change the color according to the measured value, for example, according to stages such as normal, caution, or abnormal.

[0037] Furthermore, by notifying the flow meter 52 of an abnormal reading when a blockage occurs, it is possible to confirm whether there is a problem with the blockage detection device 51 itself, similar to the device using the shut-off valve 46 described above. In other words, if the flow meter 52 reading becomes abnormal and a blockage in the detection pipe 32 is confirmed, but the detection switch 36 does not activate, a malfunction in the branch pipe 34, detection switch 36, etc., can be suspected, and these can be inspected and restored as necessary.

[0038] Furthermore, as shown in Figure 6, multiple detection tubes 32A to 32D may be arranged in the hopper 24 of a single electrostatic precipitator 21. These detection tubes 32A to 32D are positioned so that their tips face different locations within the hopper 24 (for example, areas prone to clogging). In Figure 6, blowers and the like are omitted, but air may be supplied to these detection tubes 32A to 32D from a single blower, or a blower may be connected to each detection tube 32. Then, as shown in Figure 7, the tips (cylindrical portions 34a) of the branch pipes 34A to 34D from each detection pipe 32A to 32D are gathered and arranged in one place, and their detection switches 36A to 36D are connected to the control unit 38.

[0039] By arranging multiple detection tubes 32A to 32D in the hopper 24 in this way, if a blockage is detected in any one of these detection tubes 32A to 32D, one of the detection switches 36A to 36D will activate and notify the alarm 37. Therefore, partial blockages in the hopper 24 can be detected early, and the location of the blockage can also be detected by the detection tubes 32A to 32D, making the restoration work easier.

[0040] Alternatively, as shown in Figure 8, the exhaust gas treatment device 55 may be configured with two electrostatic precipitators 21A and 21B, and each electrostatic precipitator 21A and 21B may be equipped with detection tubes 32A and 32B, branch tubes 34A and 34B, detection switches 36A and 36B (detection switches etc. are omitted in Figure 8), and a switching valve 56 may be provided in the exhaust gas passage 22 to selectively switch the flow path to either one of the electrostatic precipitators 21A or 21B.

[0041] With this configuration, the exhaust gas passage 22 is connected to one of the two electrostatic precipitators 21A and 21B, electrostatic precipitator 21A, to shut off the flow of exhaust gas to the other electrostatic precipitator 21B. While collecting dust with electrostatic precipitator 21A, if a blockage is detected, the switching valve 56 is activated to shut off the flow of exhaust gas to the blocked electrostatic precipitator 21A, and the flow path of the exhaust gas passage 22 is switched to the other electrostatic precipitator 21B, allowing inspection and repair work to be carried out on the blocked electrostatic precipitator 21A.

[0042] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, although the detection switch is configured as a limit switch, a reflective or transmissive photoelectric switch may be used, in which a light-emitting element and a light-receiving element are placed slightly above the aperture 42 to detect the floating object 35 protruding from the aperture 42. Furthermore, in the example shown in Figure 8, a blower is provided for each detection tube of the electrostatic precipitator, but it is also possible to supply gas to each detection tube from a single blower. Additionally, instead of two electrostatic precipitators, three or more may be provided. Furthermore, the electrostatic precipitator clogging detection device and exhaust gas treatment device of the present invention can be applied not only to cement manufacturing facilities but also to various plants that generate exhaust gas. [Explanation of symbols]

[0043] 1. Cement manufacturing equipment 2. Raw material storage 3. Raw material mill and dryer 4 Preheater 5. Cement Kiln 11 Chimney 20,55 Exhaust gas treatment equipment 21, 21A, 21B Electrostatic Precipitator 22 Exhaust gas passage 23 Electrostatic precipitator unit 24 Hoppa 25 Conveyor paths 31, 45, 51 Blockage detection device 32, 32A~32D Detector tubes 33 Blower 34, 34A~34D Branch pipe 34a Cylindrical part 35 Floating body 36, 36A~36D Detection Switch 37 Alarm 38 Control Unit 41 Ring section 42 Aperture 46 Shut-off valve 52 Flow meter

Claims

1. A device for detecting blockage in a hopper in an electrostatic precipitator having an electrostatic precipitator body connected to an exhaust gas passage and a hopper installed at the lower part of the electrostatic precipitator body, characterized in that it comprises a detection tube installed in the hopper, a blower that supplies gas to the detection tube, a branch tube branched from the detection tube with its tip pointed upward, a floating body provided at the tip of the branch tube and rising due to the pressure inside the branch tube, a detection switch operated by the floating body, and a blockage alarm that notifies the operation of the detection switch.

2. The electrostatic precipitator clogging detection device according to claim 1, characterized in that a shut-off valve is provided between the branching point of the detection tube and the branching tube and the tip of the detection tube.

3. The electrostatic precipitator clogging detection device according to claim 1, characterized in that a plurality of detection tubes connected to the blower are installed in the hopper, and a branch pipe is provided for each detection tube.

4. The clogging detection device for an electrostatic precipitator according to claim 1, characterized in that a flow meter is provided in the detection tube.

5. An exhaust gas treatment apparatus comprising an electrostatic precipitator clogging detection device according to any one of claims 1 to 4.

6. The exhaust gas treatment apparatus according to claim 5, wherein two or more electrostatic precipitators are provided, and the electrostatic precipitators are provided with the detection pipe connected to the blower, the branch pipe, the float, and the detection switch, and the exhaust gas passage is provided with a switching valve that can switch the flow path to one of the electrostatic precipitators.

7. A cement manufacturing facility comprising the exhaust gas treatment device described in claim 5, The aforementioned exhaust gas passage is characterized in that it is used to circulate exhaust gas generated in a cement kiln.

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