JP2013112525A - Ash clogging preventing device for hopper for ash or the like, and its ash clogging preventing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly perform ash removing operation by eliminating ash clogging during ash removal since it takes much trouble and cost to perform the ash removing operation when a hopper etc. which stores ash is high in a frequency of ash clogging in the ash removing and the ash removing operation may be interrupted, and a person needs to perform the ash removing operation and cleaning operation every time ash clogging occurs.SOLUTION: A compressed air injection hole is formed at a hopper inner wall to blow compressed air obliquely downward to the ash in the hopper and thereby to blow and suspend the ash. Furthermore, a pipe is extended across an ash discharge opening at a lower part of the hopper near the ash discharge opening, and compressed air is blown in obliquely upward from a hole in a pipe side face. In a large-sized hopper, compressed air is blown into a screw conveyor and a lower hopper from a hole formed at a hollow shaft side face of a screw conveyor at an ash discharge opening to suspend ash, and the flowability of the ash is increased to avoid blockade.

Description

  The present invention relates to an ash clogging prevention device and an ash clogging prevention method in a hopper when extracting combustion ash generated in a boiler of a power plant or the like and captured by an electric dust collector or the like from an ash storage hopper or the like.

  Combustion ash generated in a boiler of a large facility such as a power plant is introduced into an electric dust collector through a denitration device and an air preheater together with combustion exhaust gas, and most of it is captured by the electric dust collector. A plurality of inverted cone type or inverted pyramid type hoppers are installed at the bottom of the electric dust collector, and the captured combustion ash is accumulated in the hoppers.

  The combustion ash accumulated in each hopper of the electric dust collector is sucked by a suction blower through an ash transport pipe and transported to an ash suction bagging device or the like. When the suction blower is activated, an air flow is generated through the ash transport pipe under the electrostatic precipitator hopper and toward the ash suction bagging device. Therefore, when the ash discharge gate of the electrostatic precipitator hopper is opened, the combustion ash becomes ash. It is sucked into the transport pipe and transported. The transportation of combustion ash from a plurality of hoppers is performed by sequentially opening the ash discharge gate and sucking the combustion ash one by one.

  The ash suction bagging apparatus includes a bag filter and a suction blower. The suction blower suction port is connected to the bag filter outlet nozzle by piping, and the suction blower discharge port is open to the atmosphere. The ash transport pipe from the electrostatic precipitator is connected to the inlet nozzle of the bag filter, and the combustion ash is separated from the air by the bag filter and accumulated in the lower hopper of the bag filter. When the lower hopper is full, the bag filter front valve or the suction blower front valve is closed, the suction of combustion ash is temporarily stopped, and the combustion ash accumulated in the lower hopper is extracted. At this time, the discharge damper of the bag filter is opened to remove the combustion ash, but the combustion ash is light in weight and cannot be extracted smoothly due to ash clogging due to cross-linking phenomenon between the combustion ash particles or adhesion to the hopper wall surface. There are many. When ash clogging occurs, it is necessary to open the manhole of the bug filter and scrape the ash manually.

  In addition to the bag filter hopper of the above ash suction bagging apparatus, ash clogging at the time of extracting the combustion ash is often seen in an electric dust collector hopper, a combustion ash storage hopper, a combustion ash storage silo, and the like. As technology to prevent ash clogging, air blowing, use of a stirrer, use of electromagnetic knocker, etc. are carried out, but none of them are perfect, stop the ash extraction work when ash is blocked, and install manholes such as bug filters You can't get it without opening it and scraping it out by hand.

  For example, the “hopper ash clogging elimination device and method for eliminating ash clogging of combustion ash” in Patent Document 1 is a method of removing a mass of combustion ash by blowing downward compressed air along the inner wall surface of the hopper from the top of the combustion ash. It is blown off and dropped, and compressed air is blown upward along the inner wall surface of the hopper from the lower part of the hopper so as to open through holes in the mass of combustion ash. Moreover, the “hopper deposit removal device and the hopper deposit removal method” in Patent Document 2 is a method of injecting hot water from a washing water nozzle onto the wet ash attached to the hopper to wash away the wet ash, and the washing sewage is different from the ash transport pipe. A conveying path is provided to wash away in the drain side groove.

  Further, Non-Patent Document 1 discloses that a powder cross-linking phenomenon (powder adhesion, frictional force, consolidation due to changes in physical or chemical properties, etc. causes a certain portion in the powder layer to be above it. A support force sufficient to support the powder pressure must be generated.When cross-linking occurs, the upper powder is supported only by cross-linking even if there is no support force below the layer. (1) Enlarge the exit dimension as a measure to prevent obstruction due to occlusion when the body is discharged. (2) Smooth the wall surface. (3) Increase the wall angle (steep). Use vertical walls and vertical dividers. (4) Make the hopper asymmetrical. (5) The powder pressure is killed by enlarging the cross section in the middle of the hopper, where crosslinking is likely to occur. Alternatively, a protrusion is provided so that the powder pressure from above is not applied. (6) Apply vibration (however, if there is no vibration during powder discharge, there is a risk of forming a strong cross-link). (7) Using a perforated plate or the like, air is blown to fluidize the powder. (9) mechanically stirring to break the crosslinks. (10) As a general measure, for example, a hole is provided at a convenient place to break the bridge in the event that the bridge is blocked. Also, in the same document, as a measure for preventing powder from adhering to the hopper wall surface, (1) the wall angle is increased to be as close to vertical as possible. (2) Smooth the wall surface. (3) The part where the two surfaces meet is as rounded as possible. (4) Giving vibration is a common measure.

JP 2010-143659 “Hopper ash clogging elimination device for combustion ash and the like and ash clogging elimination method” Japanese Patent Application Laid-Open No. 2003-236487 “Hopper deposit removal apparatus and hopper deposit removal method” Chemical Engineering Association: “Chemical Engineering Handbook, 3rd revised edition”, pages 840 to 841, Maruzen (Showa 48)

  In conventional electric dust collector hoppers, bag filter hoppers, storage hoppers, storage silos, and the like that store combustion ash, ash clogging is frequently performed when the combustion ash is extracted, and the ash extraction operation is forced to be interrupted. Various measures against ash clogging have been taken, but there is still no effective method. When ash clogging occurred, it was necessary to perform ash removal and cleaning work manually, and this ash removal work required a lot of labor and cost.

  As countermeasures for preventing ash clogging that have been taken in the past, for example, “Hopper ash clogging elimination apparatus and method for eliminating ash clogging of combustion ash etc.” in Patent Document 1 However, it was not a technique to prevent ash clogging by increasing fluidity so that the combustion ash does not solidify. In addition, “Hopper deposit removal device and hopper deposit removal method” in Patent Document 2 is a technology that removes wet ash adhering to the hopper by injecting hot water into the hopper from the washing water nozzle. It was not a technology to prevent ash clogging by increasing ash fluidity. Non-Patent Document 1 describes various methods for preventing clogging of powders such as combustion ash and methods for increasing the fluidity of powders. Is not described.

  The present invention was devised to solve such a problem. The object of the present invention is to provide a simple device for the combustion ash hopper to increase the fluidity without cross-linking the combustion ash in the hopper. Thus, an ash clogging prevention device and an ash clogging prevention method are provided that eliminate ash clogging during ash extraction and facilitate the extraction operation.

  The invention of claim 1 is applied to a small combustion ash storage tank 1 with a hopper having a diameter of approximately 3 m. The hopper shape is an inverted conical shape, and the lower hopper 2 is provided with an ash discharge port 8 at the lower part. A compressed air injection port 4 is provided on the inner wall of the lower hopper 2, and compressed air is blown obliquely downward toward the combustion ash in the lower hopper 2, and the combustion ash is blown off and floated at the same time. By passing the pipe 5 across the ash discharge port 8 and blowing compressed air obliquely upward from the compressed air blowing hole 9 on the side surface of the pipe 5 to blow off the combustion ash, the ash is raised and the ash is not blocked. It is comprised as follows.

  In the event that combustion ash crosslinks and closes the wall surface in the lower hopper 2, an electromagnetic knocker 6 or the like is attached to the outer surface of the hopper side surface. When the ash is clogged and the ash cannot be extracted, the electromagnetic knocker 6 is operated to apply an impact to the lower hopper 2 to break the bridge.

  The invention of claim 2 is applied to the large combustion ash storage tank 30 with a hopper. The hopper has an inverted pyramid shape, and has an elongated rectangular ash discharge port 8 at the bottom, and the ash discharge port 8 has a U-shaped trough. A compressed air injection port 4 is provided on the inner wall of the lower hopper 2 with respect to the hopper on which the mold screw conveyor 31 is installed. The compressed air is blown obliquely downward toward the combustion ash in the hopper, and the combustion ash is blown off and floated at the same time. Furthermore, the flow of the combustion ash is caused by blowing the compressed air into the screw conveyor 31 and the lower hopper 2 through the compressed air blowing holes 35 on the side surface of the hollow shaft 32 of the U-shaped trough screw conveyor 31 below the hopper, and floating the combustion ash. It is constructed so that the combustion ash is not blocked when the combustion ash is extracted from the ash discharge port 8 by the screw conveyor 31.

  As with the small combustion ash storage tank 1 with a hopper, the outer surface on the side surface of the hopper is prepared in the event that the combustion ash is bridged and blocked in the lower hopper 2 as in the case of the small combustion ash storage tank 1 with a hopper. Attach electromagnetic knocker 6 etc. to

  The ash clogging prevention device of the present invention for the inverted cone type hopper of the small combustion ash storage tank 1 with a hopper has a diameter 1 of 6 to 15 tip nozzles of four compressed air injection ports 4 attached to the inner surface of the lower hopper 2. Compressed air is blown diagonally downward through a pore of ˜4 mm to blow off combustion ash, and at the same time, ash is floated to improve fluidity, and further, a compression of 1 to 5 mm in diameter opened on the side of the pipe 5 near the ash outlet 8 From the air blowing hole 9, compressed air is blown obliquely upward to blow off the combustion ash, and at the same time, the ash is floated to improve fluidity.

  The pipe 5 in the vicinity of the ash discharge port 8 may be a round pipe, a square pipe, or a pipe having any cross-sectional shape, but it has a shape that does not obstruct the flow of combustion ash from above as much as possible, that is, a wedge-shaped pipe with a wedge tip. It is desirable to arrange with the upward facing.

  The ash clogging prevention device of the present invention for the inverted pyramid hopper of the large combustion ash storage tank 30 with a hopper has 6 to 15 tip nozzles of the 6 to 12 compressed air injection ports 4 attached to the inner surface of the lower hopper 2. Compressed air is blown diagonally downward from a pore having a diameter of 1 to 4 mm to blow off the combustion ash, and at the same time, the ash is floated to increase the fluidity. The compressed air is blown into the screw conveyor and the hopper through the compressed air blowing holes 35 having a diameter of 1 to 6 mm opened in two rows at a pitch of 100 to 300 mm in the longitudinal direction to raise the fluidity of the combustion ash by floating the combustion ash, The combustion ash is configured not to be blocked in the hopper when the combustion ash is extracted by the screw conveyor 31. The compressed air is supplied to the hollow shaft 32 of the screw conveyor 31 by connecting a pipe from a compressed air source to the compressed air connection port 36 at the shaft end of the hollow shaft 32.

Effect of the invention

  In the invention having the above-described configuration, the combustion ash is blown away, and at the same time, the ash is floated to increase the fluidity. As in the past, due to ash clogging, the ash can be extracted smoothly without manually scraping off the ash from the manhole.

FIG. 1 is a schematic front view of a small combustion ash storage tank with a hopper. FIG. 2 is a schematic side view of a small combustion ash storage tank with a hopper. FIG. 3 is a detailed sectional view in the front direction of the lower part of the hopper. FIG. 4 is a detailed cross-sectional view in the side direction of the lower part of the hopper. FIG. 5 is a detailed view of the lower part of the hopper as seen from the “AA” arrow. FIG. 6 is a front view of the bag filter of the ash suction bagging apparatus according to the first embodiment. FIG. 7 is a side view of the bag filter of the ash suction bagging apparatus according to the first embodiment. FIG. 8 is a flow chart of combustion ash from the electric dust collector to the ash suction bagging device. FIG. 9 is a schematic front view of a large combustion ash storage tank with a hopper. FIG. 10 is a schematic side view of a large combustion ash storage tank with a hopper. FIG. 11 is a detailed view of the hollow shaft of the screw conveyor.

  Hereinafter, preferred embodiments of the present invention will be described by way of examples. FIGS. 6, 7 and 8 show an embodiment in which the present invention is applied to a combustion ash suction bagging apparatus comprising a small bag filter and a suction blower. As shown in the flow diagram of FIG. 8, the combustion ash captured by the electrostatic precipitator 20 disposed in the boiler flue is accumulated in the electrostatic precipitator hopper 21, and the suction blower 25 of the ash suction bagging device 24. And is introduced into the bag filter 10 of the ash suction bagging device 24 via the ash transport pipe 23. The combustion ash and air are separated by the bag filter 10, the combustion ash is accumulated in the lower hopper 2 of the bag filter, and the air is discharged from the discharge port of the suction blower 25 to the atmosphere.

  After the combustion ash suction operation for a certain time, when the lower hopper 2 of the bag filter 10 is filled with combustion ash, the suction blower front valve 28 and the bag filter front valve 27 are closed and combustion from the electric dust collector 20 is performed. The suction of ash is temporarily stopped and the combustion ash is extracted from the bag filter 10. After the combustion ash in the bag filter 10 is extracted and transferred to the ash collection bag 26, the bag filter front valve 27 and the suction blower front valve 28 are opened to perform the suction operation of the combustion ash from the electric dust collector 20. Resume. This operation is repeated until the combustion ash in the electrostatic precipitator hopper 21 disappears.

  As shown in FIGS. 6 and 7, the ash clogging prevention device of the present invention is provided in the lower hopper 2 of the small bag filter 10 of the ash suction bagging device 24. The size of the bag filter 10 is 1640 mm in diameter × 2360 mm in height. Of these, the lower hopper 2 has an inverted conical shape with an upper diameter of 1640 mm, a lower diameter of 500 mm, a height of 990 mm, and a cone angle of 60 degrees. The lower part of the inverted conical shape is an ash discharge port 8 to which the ash discharge damper 3 is attached. The compressed air injection ports 4 were attached to four locations on the cone circumference at a height of 450 mm above the ash discharge port 8, and twelve pores having a diameter of 1.5 mm were opened at the tip of the injection port 4. With a nozzle. The four injection ports 4 are arranged at equal intervals on the circumference of the cone, and the individual injection ports 4 are attached to the wall surface of the lower hopper 2 obliquely downward at an angle of 45 degrees. In addition, a wedge-shaped pipe 5 (tip angle: 36 degrees, length: 100 mm × width: 60 mm × length: 500 mm) is attached in the vicinity of the lower ash discharge port 8 so as to cross the ash discharge port 8. The wedge-shaped pipe 5 is attached so that the wedge tip is directed upward, and five compressed air blowing holes 9 having a diameter of 4 mm are opened at equal intervals on both sides of the wedge-shaped pipe 5 at a position 30 mm below the wedge tip. ing. An ash discharge damper 3 is attached to the ash discharge port 8. Further, a short pipe 13 having a diameter of 820 mm is attached to the single pipe connecting flange 14 of the ash discharge port 8. The mouth of the ash collection bag 26 is attached to the short pipe 13, and the outer periphery of the bag is tied with a string so It is fixed so as not to leak from the gap between the short tube 13 and the ash collection bag 26.

  In the operation of sucking combustion ash from the electric dust collector 20, first, the ash discharge damper 3 under the lower hopper 2 of the bag filter 10 is closed, the ash collection bag 26 is attached, and the compressed air injection nozzle 4 of the lower hopper 2 is attached. Then, the blowing of compressed air from the compressed air blowing hole 9 of the wedge-shaped pipe 5 to the hopper is started. Thereafter, the suction blower 25 of the ash suction bagging device 24 is activated, the bag filter front valve 27 and the suction blower front valve 28 are opened, and the combustion ash is sucked from the electric dust collector hopper 21. Air and combustion ash are separated by the bag filter 10 of the ash suction bagging device 24, and the air is discharged to the atmosphere from the discharge port of the suction blower 25, but the combustion ash is accumulated in the lower hopper 2 of the bag filter 10. While the operation is continued, when the lower hopper 2 is filled with combustion ash, the suction blower front valve 28 and the bag filter front valve 27 are closed to temporarily stop the suction of the combustion ash. The combustion ash that is gradually accumulated in the lower hopper 2 of the bag filter 10 is blown off by the compressed air blown into the lower hopper 2 and floated to improve the fluidity, and is accumulated in a state where almost no crosslinking occurs.

  The combustion ash accumulated in the lower hopper 2 of the bag filter 10 is dropped into the ash collection bag 26 fixed to the short tube 13 by opening the ash discharge damper 3 of the ash discharge port 8 below the hopper. Also at this time, the ash in the lower hopper 2 is blown away by the compressed air blown from the compressed air blown injection port 4 and the compressed air blown hole 9 of the wedge-shaped pipe 5 in cross section, and is floated and closed in a highly fluid state. Without falling into the collection bag 26.

  After all of the combustion ash in the lower hopper 2 of the bag filter 10 has been extracted, the ash discharge damper 3 is closed, and the mouth of the ash collection bag 26 is tied with a string to close the mouth. The string fixed to the short tube 13 is loosened and the collection bag 26 is removed from the short tube 13.

  The bag filter front valve 27 and the suction blower front valve 28 are opened again, and the combustion ash is sucked from the electric dust collector hopper 21. The ash suction operation is continued until the lower hopper 2 of the bag filter 10 is filled with combustion ash, and when the ash is full, the same operation as described above is performed to extract the ash in the lower hopper 2 of the bag filter 10. Thereafter, the same operation is repeated until all the combustion ash in the electrostatic precipitator hopper 21 is completely extracted.

  The hopper ash clogging prevention apparatus and the ash clogging prevention method of the present invention, such as combustion ash, can be applied to hoppers and silos used for storage of combustion ash, etc., such as bag filters.

1. Small combustion ash storage tank with hopper 2. Lower hopper 3. Ash discharge damper4. 4. Compressed air injection port 5. Wedge-shaped pipe 6. Electromagnetic knocker Manhole 8. Ashes outlet 9. Compressed air blowing hole 10. Bug filter11. Inlet nozzle 12. Outlet nozzle 13. Short tube 14. Single pipe connection flange 15. Mounting frame 20. Electric dust collector 21. Electric dust collector hopper 22. Ash discharge gate 23. Ash transport tube 24. Ash suction bagging device 25. Suction blower 26. Ash collection bag 27. Bag filter front valve 28. Suction blower front valve 30. Large combustion ash storage tank with hopper 31. Screw conveyor 32. Hollow shaft 33. Motor 34. Screw conveyor blades 35. Compressed air blowing hole 36. Compressed air connection port

Claims (2)

  In a small hopper that stores combustion ash and the like that has an inverted cone shape and has an ash discharge port in the lower part, a compressed air injection port is provided on the inner wall of the hopper, and compressed air is inclined obliquely downward toward the combustion ash in the hopper. Blowing and blowing off the combustion ash at the same time, and passing a pipe across the ash outlet near the ash outlet at the bottom of the hopper, and blowing compressed air obliquely upward from a hole on the side of the pipe, An apparatus for preventing ash clogging of a hopper such as combustion ash and the like and a method for preventing the ash clogging configured to increase the fluidity of the combustion ash and to prevent the combustion ash from being blocked when it is extracted from the ash discharge port by blowing off the combustion ash.   In a large hopper that has an inverted pyramid shape and has an elongated rectangular ash discharge port at the bottom, and a U-shaped trough screw conveyor installed in the ash discharge port for storing combustion ash, etc., a compressed air injection port is provided on the inner wall of the hopper Compressed air is blown obliquely downward toward the combustion ash in the hopper, the combustion ash is blown off and floated at the same time, and further compressed into the screw conveyor and the hopper through the holes on the side of the hollow shaft of the screw conveyor. Injecting air and floating the combustion ash to increase the fluidity of the combustion ash, such as combustion ash configured so that the combustion ash is not blocked when the combustion ash is extracted from the ash discharge port by the screw conveyor Hopper ash clogging prevention apparatus and ash clogging prevention method therefor.

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