JP2013221645A - Shot ball scattering device and shot ball scattering method for shot cleaning, and boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shot ball scattering device, which is constituted by branching a shot ball conveyance path into a plurality and arranging a channel selector valve at a branch point, and includes the channel selector valve capable of suppressing the occurrence of an operation defect due to a collision of a shot ball.SOLUTION: A channel selector valve includes: a casing in a short columnar shape; a supply port and a plurality of discharge ports each formed on an outer peripheral surface of the casing and having tube ends extending inward compared to an inner peripheral surface of the casing; and a valve body which links a discharge port selected out of the plurality of discharge ports to the supply port while interposing a gap between the tube ends of the supply port and discharge ports, and can rotate around a longitudinal axis of rotation of the casing.

Description

  The present invention relates to a shot ball spraying device for shot cleaning, a shot ball spraying method, and a boiler including a shot ball spraying device that sprays shot balls such as steel balls in a boiler to remove dust adhering to a heat transfer tube. About.

  The boiler includes a economizer, a superheater, and an evaporator for generating steam. FIG. 6 shows a casing 1d of the boiler 1 that introduces high-temperature boiler gas (for example, combustion gas from the combustion chamber) from the bottom side and discharges it from the top side, and the superheater 1c and the evaporator are disposed in the casing 1d. 1b and a economizer 1a are arranged. The superheater 1c, the evaporator 1b, and the economizer 1a generally have a heat transfer tube type heat exchanger structure, and water that is passed through the heat transfer tube is heated to steam by the heat of the boiler gas. .

  Since the boiler gas is accompanied by dust (for example, fly ash), the heat exchange efficiency decreases when the dust adheres to the gas side heat transfer surface of the heat transfer tube. When the heat exchange efficiency of the superheater 1c, the evaporator 1b, and the economizer 1a is lowered, the boiler efficiency is lowered as a result. Therefore, methods for removing dust adhering to the heat transfer tube have been studied conventionally. As a method for removing dust, a soot blower method is known in which a fluid such as steam or compressed air is jetted to blow away dust adhering to the surface of the heat transfer tube. However, in the case of the soot blower system, there is an increase in cost due to consumption of fluid, and when steam is used, the steam recovery rate of the boiler 1 is lowered.

  The present inventors have realized a dust removal method of a shot cleaning method as disclosed in Patent Document 1 as a new dust removal method that replaces the soot blower method. The dust removal method disclosed in Patent Document 1 is a method in which steel balls, which are shot balls, are sprayed from the upper part of the casing 1d and dust is shaken off by colliding the free-falling steel balls with the heat transfer tubes. The steel balls are collected from the bottom of the casing 1d and reused.

  The configuration of the shot ball spraying device will be described with reference to FIG. A steel ball 100 as a shot ball is stored in the steel ball tank 2 and is quantitatively cut out by a cutting device such as the rotary feeder 21. The steel ball 100 cut out by the rotary feeder 21 is supplied into the steel ball transport pipe 22 and is accelerated by a transport gas (for example, high-pressure air) blown into the pipe from a blower 23 as a transport gas generator to transport the steel ball. It flows through the tube 22 and is conveyed to the boiler 1. Reference numeral 23a is a shut-off valve that opens when the blower 23 is activated.

  The steel balls 100 injected from the tip of the steel ball transport pipe 22 strike and collide with the collision plate 24 and are uniformly dispersed in the casing 1 d of the boiler 1. The steel ball 100 falls freely in the casing 1d, collides with the heat transfer tube, and shakes off the dust. The steel ball 100 and dust that have fallen to the bottom of the casing 1d are recovered by the steel ball recovery device 26 via the guide chute 25. The steel ball 100 and dust are separated into powdery dust, the steel ball 100, and lump dust in the steel ball recovery device 26, and the steel ball 100 is returned to the steel ball tank 2. The powdery dust is supplied into the dust transport pipe 28 through the dust powder cutting rotary valve 27 and collected. On the other hand, massive dust is supplied into the dust transport pipe 28 through the massive cutout double valve 29 and collected.

JP 2009-127908 A

  The shot ball spraying device disclosed in Patent Document 1 has a single spraying position on the boiler 1. In order to uniformly disperse the steel balls 100 in the boiler 1, it may be preferable to set a plurality of dispersal positions. However, since the blower 23 that generates the airflow for conveyance is a large type that uses power of 30 KW or more to flow the steel ball 100, it is not economical to install as many blowers 23 as the number of spraying positions. Therefore, the steel ball conveyance pipe 22 is branched in the middle, and the tip of the branched conveyance pipe is introduced into a different position of the boiler 1, and the conveyance path of the steel ball 100 is selectively switched by the flow path switching valve arranged at the branch point. It is desirable to do.

  The present inventors examined a three-way valve as shown in FIG. 7 as a flow path switching valve. In the three-way valve, a supply nozzle 32, a first discharge nozzle 33, and a second discharge nozzle 34 are formed in a casing 31, and a vent pipe 35 as a valve body is rotatably disposed in the casing 31. . This three-way valve selects only one of the discharge nozzles 33 (34) as the transport path by the rotation operation of the vent pipe 35. More specifically, FIG. 7 shows a state where the vent pipe 35 is positioned so that the supply nozzle 32 and the first discharge nozzle 33 are in communication with each other, and the first discharge nozzle 33 side is selected as the conveyance path. On the other hand, when the second discharge nozzle 34 side is switched to the conveyance path, the vent pipe 35 is rotated about 120 degrees around the longitudinal rotation axis Q of the casing 31 (rotation axis perpendicular to the paper surface) and supplied in FIG. The pipe end of the vent pipe 35 located on the nozzle 32 side is located on the second discharge nozzle 34 side, and the pipe end of the vent pipe 35 located on the first discharge nozzle 33 side is located on the supply nozzle 32 side. Like that.

  The valve generally used is sealed between the valve body and the casing by a resin-based sealing material using polytetrafluoroethylene (PTFE) or the like. This is a metal touch seal structure in which a sleeve 36 is pressed against the joint between the vent pipe 35 and the nozzles 32, 33, 34.

  In this case, when the vent pipe 35 is rotated in order to switch the transport path, the metal touch portion slides in contact with each other, so that a strong switching driving force is required. Further, if the metal touch sheet is damaged by the collision of the steel balls, the sealing performance is deteriorated, and if the deformation further progresses, the rotation operation of the vent pipe 35 as a valve body may be hindered. In addition, when the sealing performance is deteriorated, dust accompanying the steel ball 100 may enter between the vent pipe 35 and the casing 31 to accelerate the rotational operation failure, resulting in an opening / closing failure.

  Furthermore, the present inventors examined the applicability of a powder transfer switching valve as disclosed in, for example, JP-A-5-209691 as a flow path switching valve for shot ball transfer. However, since this switching valve has a sliding part (seal packing) in the valve, when the steel ball 100 collides with the sliding part and the deformation occurs, the rotating operation of the valve body is hindered. There is a case. Further, a gap is formed between the direction switching pipe and the casing inner peripheral surface. However, when the casing inner peripheral surface is deformed (for example, unevenness) due to the impact of the steel ball 100, the direction switching valve is generated. May not be able to rotate. For this reason, this valve can be used for powders, but cannot be used for conveying shot balls having high strength and large particle diameter such as steel balls 100.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to set a shot ball conveyance path so that a spray position in a boiler of a shot ball such as a steel ball can be selected and switched. A shot sphere spraying device and a shot sphere equipped with a flow path switching valve capable of suppressing the occurrence of malfunction due to a collision of a shot ball in a configuration in which the flow path switching valve is branched at a branch point. It is to provide a spraying method and a boiler.

That is, the gist of the present invention is as follows.
(1) A shot ball transport device that transports a shot ball for shot cleaning in an air stream, and a pipe that connects the shot ball transport device and the boiler, and a tip opening that branches off in the middle and injects the shot ball is a boiler Each including a shot ball transport pipe introduced therein, and a flow path switching valve that is arranged at a branch point of the shot ball transport pipe and selectively switches a branch path for transporting a shot ball from the branch path, In the shot ball spray device for shot cleaning that sprays shot balls in the boiler and removes dust adhering to the heat transfer tubes,
The flow path switching valve has a short cylindrical casing, and a supply port and a plurality of discharge ports that are formed on the outer peripheral surface of the casing and have pipe ends extending inward from the inner peripheral surface of the casing. The exhaust port selected from the plurality of exhaust ports and the supply port in a communication state with a gap interposed between the supply port and the pipe end of the discharge port. A shot ball spraying device comprising: a valve body rotatable around a vertical rotation shaft.
(2) The distal ends of the pipe ends of the supply port and the discharge port are formed in an R shape along a virtual circle centered on the rotation axis of the valve body, and the tubes of the supply port and the discharge port The tip portion of the valve body facing the tip of the end portion with a slight gap is also formed in an R shape along a virtual circle centered on the rotation axis of the valve body. The shot ball spraying device according to (1).
(3) The pressurizing pipe is connected to the casing so that the pressure in the casing becomes higher than the pressure in the shot ball transport pipe at least in the connection portion with the supply port. The shot ball spraying device according to (1) or (2), wherein a part of the transfer gas from the transfer gas generator is directly introduced into the shot ball transfer device during shot cleaning.
(4) The tip opening of each branch path introduced into the boiler is closed when the channel switching valve is not selected by the flow path switching valve during shot cleaning, and the tip opening is closed. The shot ball transport device according to any one of (1) to (3), wherein an open / close lid type shut-off valve for shutting off a communication state with the boiler is provided.
(5) A boiler provided with the shot ball spraying device according to any one of (1) to (4).
(6) A flow path switching valve disposed at a branch point of the shot ball transport pipe, in which the shot spheres are air-flow transported through the shot ball transport pipes each of which has a plurality of branched branch end openings introduced into the boiler. A shot ball spraying method for shot cleaning that selectively removes the branch path that transports the shot sphere by spraying and removes dust adhering to the heat transfer tube by spraying the shot sphere into the boiler from the tip opening of the selected branch path In
A short cylindrical casing, a supply port and a plurality of discharge ports formed on the outer peripheral surface of the casing and having a pipe end extending inward from the inner peripheral surface of the casing, and the supply port and the discharge port It is possible to rotate around the longitudinal rotation axis of the casing that brings the discharge port selected from the plurality of discharge ports into communication with the supply port in a state where a gap is interposed between the tube end portion of the outlet A shot ball scattering method characterized by selectively switching a branch path for transporting a shot ball using a flow path switching valve provided with a valve body.

  According to the shot ball spraying device for shot cleaning of the present invention, the supply port and the plurality of discharge ports formed in the short cylindrical casing have a pipe end portion extending inward from the casing inner peripheral surface. A valve body rotatable around a longitudinal rotation axis of the casing rotates with a gap interposed between the supply port and the pipe end of the discharge port, and is selected from the plurality of discharge ports. By adopting a flow path switching valve that connects the discharge port and the supply port with the gap interposed therebetween, there is no sliding portion due to the provision of the gap, and there is some damage. However, there is no problem with the rotation of the valve body. In particular, since the pipe end portion extending inward from the casing inner peripheral surface is formed, the separation distance between the valve element and the casing inner peripheral surface is large in the region other than the gap. Therefore, even if there is dust that has entered the casing, there is no problem with the rotation of the valve body.

  Further, according to the present invention, it is preferable that the pressure pipe for pressurizing the inside of the casing is connected to the casing so that the pressure in the casing is higher than the pressure in the shot ball transport pipe at least at the connection portion with the supply port. In addition, by introducing a part of the transfer gas generated by the shot ball transfer device during shot cleaning through the pressurizing tube, it is more reliably accompanied with the shot ball between the valve body and the casing. It is possible to suppress the coming dust from entering the casing, and to suppress the occurrence of malfunction due to the dust intrusion.

1 is an overall configuration diagram of a shot cleaning system including a shot ball spraying device according to a preferred embodiment of the present invention. It is a top view which shows the flow-path switching valve of the said shot ball spraying apparatus. It is a horizontal sectional view which shows the flow-path switching valve of the said shot ball spraying apparatus. It is a longitudinal cross-sectional view which shows the flow-path switching valve of the said shot ball spraying apparatus. It is a figure which shows the pipe line shut-off valve of the said shot ball spraying apparatus. It is a whole block diagram of the conventional shot cleaning system. It is a structural diagram of a conventional flow path switching valve.

  Hereinafter, a shot ball spraying device for shot cleaning according to a preferred embodiment of the present invention will be described in detail by taking a steel ball spraying device for spraying steel balls as an example. Of course, it can be used as a device for spraying shot balls other than steel balls, such as ceramic balls. Further, the technical scope of the present invention is not construed as being limited by the embodiments described below.

  FIG. 1 is an overall configuration diagram of a shot cleaning system. About the same structure as the conventional structure, detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol. In the shot cleaning system of the present embodiment, the steel ball transfer pipe 22 is branched in the middle, and the flow path switching valve 4 is provided at the branch point. Further, the branched steel ball conveying pipes 22 (22a, 22b) are respectively connected to the upper part of the casing 1d of the boiler 1, and the pipe shut-off valves 5 (5a) are connected to the discharge ports of the respective branch paths 22a, 22b. 5b). In addition, in FIG. 1, although the structure which branched the steel ball conveyance pipe | tube 22 into 2 is shown, when branching into 3 or more, a branch path is further branched into 2 and a flow path is further added to the branch point. A switching valve 4 is provided. The posture of the flow path switching valve 4 to be arranged is not particularly limited, and can be set vertically or horizontally.

  As shown in FIGS. 2 to 4, the flow path switching valve 4 includes a short cylindrical casing 41 that forms a valve main body and a vent pipe 42 that forms a valve body that can rotate within the casing 41. The casing 41 is formed, for example, by closing both end openings of the cylindrical member 41a with a disk-shaped casing lid 41b and fixing the flanges with bolts 41c or the like. On the side peripheral surface of the casing 41, three nozzle-type openings (43, 44, 45) having flanges are formed with their phases shifted from each other in the circumferential direction (for example, at intervals of 120 degrees). A supply port through which 100 enters, a first discharge port and a second discharge port through which the steel ball 100 is discharged are configured. Although not shown, the steel ball transport pipe 22 from the blower 23 is connected to a supply nozzle 43, and the two branch paths 22a and 22b of the steel ball transport pipe 22 are a first discharge nozzle 44 and a second discharge nozzle. 45, respectively. The supply port (43), the first discharge port (44), and the second discharge port (45) do not have to be a nozzle type having a flange, and can be appropriately modified into a screwed type or the like.

  The vent pipe 42 constituting the valve body is housed in the casing 41 so as to be rotatable around a vertical rotation axis Q (rotation axis in a direction perpendicular to the paper surface) located at the center of the casing 41. A trunnion shaft 46 extending in a direction perpendicular to the curved surface is attached to the vent pipe 42. Both ends of the trunnion shaft 46 pass through opening holes formed in the centers of the upper and lower casing lids 41b, and are rotatably supported by a bearing device 46a such as a bearing. The opening hole through which the trunnion shaft 46 passes is sealed by a sealing member 46b such as a gland packing. A rotation lever 47 is provided at one end of the trunnion shaft 46, and a drive cylinder 48 for rotating the rotation lever 47 is further connected. Accordingly, by driving the drive cylinder 48 and extending and retracting the cylinder rod, the rotation lever 47 rotates the trunnion shaft 46 and the vent pipe 42 rotates around the trunnion shaft 46 as a rotation axis. Yes.

  The flow path switching valve 4 selects either the first discharge nozzle 44 or the second discharge nozzle 45 as the transport path by the rotation of the vent pipe 42. In FIG. 3, the phase of the opening in the circumferential direction of the vent pipe 42 is positioned so that the supply nozzle 43 and the second discharge nozzle 45 are in communication with each other. That is, the second discharge nozzle 45 side (OUT2) is selected as the transport path. A stopper 49b is provided in the casing 41 so that when the vent pipe 42 is rotated, the opening of the second discharge nozzle 45 and the opening of the vent pipe 42 are stopped at a position just opposite to each other. Similarly, a stopper 49a is provided so as to stop at a position where the opening of the first discharge nozzle 44 and the opening of the vent pipe 42 are just opposite to each other.

  On the other hand, when switching to the conveyance path toward the first discharge nozzle 44 side (OUT1), the drive cylinder 48 is driven to rotate the vent pipe 42 120 degrees counterclockwise around the trunnion shaft 46 as a rotation axis. 3, the pipe end of the vent pipe 42 located on the supply nozzle 43 side is located on the second discharge nozzle 45 side, and the pipe end of the vent pipe 42 located on the first discharge nozzle 44 side in FIG. It is located on the nozzle 43 side. The operation of the vent pipe 42 is restricted by the stopper 49a, and stops at a position where the opening of the first discharge nozzle 44 and the opening of the vent pipe 42 are just opposite to each other. In the case of the opening angle α shown in FIG. 3, the rotation angle of the vent pipe 42 at the time of switching the channel is 180 degrees− (α / 2) (see FIG. 2). When the opening angle α is smaller than 120 degrees, the operating angle (180 degrees− (α / 2)) of the rotating lever 47 becomes large, and the rotating lever method makes operation difficult. Therefore, a system in which the drive cylinder 48 is replaced with a rotation actuator and directly connected to the trunnion shaft 46 can be selected.

  The supply nozzle 43, the first discharge nozzle 44, and the second discharge nozzle 45 have pipe end portions 43 a, 44 a, and 45 a whose tip portions extend inward from the inner peripheral surface of the casing 41. The tube end portions 43 a, 44 a, and 45 a extend toward the longitudinal rotation axis Q of the vent tube 42. Furthermore, the pipe end portions 43a, 44a, and 45a extend to positions where a slight gap (for example, a gap δ of 0.2 to 1.0 mm) is formed between the end portions of the vent pipe 42. More preferably, the gap between the vent pipe 42 other than the pipe end portions 43a, 44a and 45a and the inner peripheral surface of the casing 41 is extended to a position where the gap δ is 10 times or more. As an example, it extends 10-15 mm. Therefore, the vent pipe 42 does not have a sliding portion when the flow path switching operation is performed, and the distance from the inner peripheral surface of the casing 41 is increased at a portion other than the gap δ that is closest to the inner peripheral surface of the casing 41. Therefore, even if dust or the like is present in the casing 41, the rotation is not immediately disturbed.

  The tips of the pipe end portions 43a, 44a, 45a of the supply nozzle 43, the first discharge nozzle 44, and the second discharge nozzle 45 are the longitudinal rotation axis Q of the casing 41 around which the vent pipe 42 rotates (that is, the axis of the trunnion shaft). ) Along an imaginary circle centered on). Further, both end portions of the vent pipe 42 are similarly formed in an R shape along a virtual circle centered on the rotation axis Q. The virtual circle on the vent pipe 42 side has a radius smaller than the virtual circle on the nozzles 43, 44, and 45 side by the gap δ.

  In addition, the casing 41 is formed with an opening hole 6 for introducing a gas for pressurization in order to adjust the pressure in the casing inner area excluding the flow path forming area in the vent pipe 42 and the nozzles 43, 44, 45. Has been. One end of a pressurizing pipe 61 shown in FIG. 1 is connected to the opening hole 6, and the other end of the pressurizing pipe 61 is connected to a position immediately after the discharge pipe of the blower 23 of the steel ball transport pipe 22. Yes. Preferably, the position is closer to the blower 23 than the rotary feeder 21. Therefore, when the blower 23 is activated to execute shot cleaning, high-pressure gas is introduced into the casing 41 through the pressurizing pipe 61. The downstream side of the rotary feeder 21 has a large pressure loss because the steel ball 100 is conveyed. Therefore, by directly introducing a part of the conveying gas as the pressurizing gas through the pressurizing pipe 61 branched from the position near the blower 23, the pressure of the pressurizing gas is reduced at least at the inlet portion of the supply nozzle 43. It is higher than the pressure in the ball transport tube 22. Therefore, the pressure in the casing 41 can be made higher than the flow path formation region, and dust is prevented from entering the casing 41 from the transport gap δ due to the pressure difference.

  The vent pipe 42 and the first discharge nozzle 44 and the second discharge nozzle 45 are preferably made of a hardened alloy steel pipe (SCM) in consideration of wear resistance, and the vent pipe 42 is hot bent. It is desirable to manufacture and quench. The state in the casing 41 can be visually inspected through the in-casing inspection window 41d.

  Next, the pipeline shutoff valve 5 will be described with reference to FIG. The pipe shut-off valve 5 includes a valve body 51, a cylinder rod 52 that supports the valve body 51, and a rotary cylinder 53 that extends, retracts, and rotates the cylinder rod 52, and these constitute an open / close lid type valve. Yes. The valve body 51 is disposed so as to face each discharge port (22a, 22b) of the steel ball transport tube 22 introduced into the boiler 1, and a position where the discharge port is covered (that is, the valve is closed). State) and a position 51b away from the discharge port by lateral movement, and further moving between a position 51b (that is, a state in which the valve is opened) retreated from the injection region of the steel ball 100 by further rotating. Is possible. The injection region of the steel ball 100 means a course region of the steel ball group that protrudes from the discharge port.

  The valve body 51 is, for example, a plate-like member, and has a seal surface area having a circular shape as shown in FIG. 5B and a size that closes the discharge port of the steel ball conveyance tube 22. The tip of the cylinder rod 52 is fixedly connected to a portion extending from the area of the seal surface. The planar shape of the valve body 21 is not limited, and can be various shapes such as a rectangular shape and an elliptical shape. Furthermore, it does not necessarily have to be plate-shaped. The valve body 51 is made of a metal material such as carbon steel or stainless steel. Moreover, the steel ball conveyance pipe | tube 22 is formed with metal materials, such as a carbon steel pipe, for example, Therefore, the junction part of the valve body 51 and the steel ball conveyance pipe | tube 22 becomes a metal touch.

  The cylinder rod 52 is arranged at a position on the upper side of the steel ball transport tube 22 so as to extend in parallel with the steel ball transport tube 22. Accordingly, when the cylinder rod 52 is retracted, the valve body 51 moves in the direction toward the discharge port of the steel ball transport pipe 22, and conversely, when the cylinder rod 52 is extended, the valve body 51 is removed from the discharge port of the steel ball transport pipe 22. Move away. Further, when the cylinder rod 52 is rotated in a state where the valve body 51 is separated from the discharge port of the steel ball conveyance pipe 22, the valve body 51 rotates around the cylinder rod 52 as a rotation axis. FIG. 5B shows a state in which the valve body 51 is rotated by 90 degrees as an example, but it is rotated to an angle at which the steel ball 100 does not collide.

  A rotary cylinder 53 is connected to the rear end of the cylinder rod 52. The rotary cylinder 53 can be fixedly disposed on the steel ball transport tube 22 as an example. The rotary cylinder 53 extends, retracts, and rotates the cylinder rod 52 by its driving operation. Such a rotary cylinder 53 is put into practical use by, for example, an electric or fluid pressure driven actuator.

  Since the side wall of the boiler 1 is thermally expanded due to a temperature difference between when it is in operation and when it is stopped, it is not preferable that the components of the pipe shut-off valve 5 are fixedly disposed on the side wall of the boiler 1. Therefore, in this example, the nozzle 1f with a flange is provided on the side wall of the casing 1d, and the tip of the steel ball transport tube 22 is introduced into the boiler 1 through the opening of the nozzle 1f. Then, a circular plate-like member 22c capable of closing the opening of the nozzle 1f is fixedly disposed on the outer peripheral surface of the steel ball conveying tube 22, and a flexible joint 54 for absorbing the thermal expansion of the boiler 1 is sandwiched therebetween. The circular plate-like member 22c and the flange of the nozzle 1f are fixed with bolts or the like. For example, a bellows-shaped joint can be used as the flexible joint 54.

  The cylinder rod 52 passes through an opening hole formed in the circular plate-shaped member 22c, and the opening hole is sealed with a seal member 55 such as a gland packing. The outer surface of the casing 1d of the boiler 1 and the surface of the circular plate-like member 22c are covered with a heat insulating material 1e.

  Further, a collision plate 24 is disposed in the casing 1 d of the boiler 1 at a position facing the discharge port of the steel ball transport pipe 22. The collision plate 24 is rotatable about a horizontal rotation shaft 24a orthogonal to the injection direction, and is rotated at an arbitrary angle θ by a rotation driving device (not shown) connected to the end of the horizontal rotation shaft 24a. It can be kept stationary. The collision plate 24 collides and disperses the steel balls 100 injected in the horizontal direction, and adjusts the dispersion state of the steel balls 100 downward by changing the angle θ, thereby spreading the steel balls 100. Level the state. Furthermore, dispersibility can be improved by changing the shape of the collision surface.

  As described above, the steel ball transport pipe 22 branches in the middle, and the ends of the branch paths 22a and 22b are introduced into the upper part of the casing 1d of the boiler 1. The pipe shutoff valve 5 is provided at the tip of each branch path 22a, 22b in the casing 1d. Furthermore, by selecting a flow path through which the steel ball 100 flows through the flow path switching valve 4, the injection location of the steel ball 100 to the boiler 1 can be switched. Then, only the pipe shutoff valve 5 of the branch path 22a (22b) selected as the flow path for spraying the steel balls 100 is opened. In other words, the pipe shutoff valve 5 of the branch path 22b (22a) that has not been selected is kept closed and the boiler 1 is kept shut off.

  The operation of the above apparatus will be described. When performing the shot cleaning, first, in order to select the conveyance path of the steel ball 100, the vent pipe 42 of the flow path switching valve 4 is rotated to either the first discharge nozzle 44 or the second discharge nozzle 45. Make sure that one is in communication. On the other hand, the valve of the pipe line shut-off valve 5 selected as the flow path is opened, and the pipe line shut-off valve 5 not selected as the flow path maintains the closed state.

  Subsequently, the blower 23 is activated and the blower discharge port valve 23 a is opened to supply the air for conveyance to the steel ball conveyance tube 22. When the blower 23 as the transfer gas generator is activated, a part of the high-pressure air is directly introduced into the casing 41 through the pressurizing pipe 61. Further, the rotary feeder 21 is activated to quantitatively cut the steel ball 100 from the steel ball tank 2 and supply the steel ball 100 into the steel ball transport tube 22. In this example, as an example, a configuration in which the shot ball transport device includes the blower 23, the rotary feeder 21, and the steel ball tank 2 is illustrated, but the configuration is not limited to these configurations. The steel ball 100 flows through the steel ball transport pipe 22 by a high-speed air flow (for example, 40 to 50 m / s) of the transport air, and is ejected from a discharge port introduced into the casing 1 d of the boiler 1. A steel ball 100 having an average particle diameter of about 6 to 10 mm is used, air is used as a carrier medium, a solid-gas ratio is 2 to 3 kg / kg, and a pipe air flow rate is 40 to 50 m / s. When the size of the steel ball 100 is changed, it is necessary to increase the air flow rate in proportion to the steel ball size.

  The steel balls 100 injected to the upper part of the casing 1d are dispersed by hitting the collision plate 24 and fall downward. And it collides with the heat exchanger tube of superheater 1c, evaporator 1b, and economizer 1a, and dust is shaken off. The steel ball 100 and dust that have fallen to the bottom of the casing 1d are recovered by the steel ball recovery device 26 via the guide chute 25. The steel ball 100 and dust are separated into powdery dust, steel balls, and lump dust in the steel ball recovery device 26, and the steel balls 100 are returned to the steel ball tank 2 for circulation. .

  When a predetermined time, for example, about 5 to 10 minutes elapses, the shot cleaning is stopped. In the stopping procedure, first, the cutting of the rotary feeder 21 is stopped, and the supply of the conveying air is continued so that the steel ball 100 is discharged from the inside of the steel ball conveying tube 22. When a certain time has elapsed, the blower 23 is stopped and the blower outlet valve 23a is closed. Subsequently, the conduit shutoff valve 5 is closed to shut off the communication state with the boiler 1. Such a series of shot cleaning operations are performed intermittently at intervals of about 5 to 10 minutes per hour, for example.

  The transfer path selection switching by the flow path switching valve 4 is performed after the above stop operation is completed. In particular, it is performed after the steel balls 100 are discharged from the steel ball transport pipe 22 so that the steel balls 100 remaining in the steel ball transport pipe 22 do not fall and collide with the casing 41 or the vent pipe 42. The selection switching is performed by rotating the vent pipe 42 as described above. The timing for executing the selection switching of the flow path is once stopped after the end of the shot cleaning operation for one flow path and at the start of the next shot operation.

  Since the dust adhering to the heat transfer tube uses the falling collision force of the steel ball 100, the size of the steel ball 100 is increased in order to increase the collision force when the adhesion force of the adhering dust is high. The diameter of the steel ball conveyance tube 22 can be set to, for example, about 100 to 150 mm, and the conveyance flow rate of the steel ball 100 can be set to 40 to 80 kg / min. The execution time and execution interval of shot cleaning are appropriately determined according to the size of the boiler 1.

  From the above, according to the present embodiment, the portion that slides when the vent pipe 42 that is the valve body operates by providing the gap δ between the nozzles 43, 44, 45 and the vent pipe 42. Disappears. Therefore, even if some scratches can be made, there is no problem in the rotation of the vent pipe 42. Moreover, since there is no sliding part, there is also an advantage that the frictional resistance when rotating the vent pipe 42 is small. Further, since each nozzle 43, 44, 45 has pipe end portions 43 a, 44 a, 45 a extending inward from the inner peripheral surface of the casing 41, the gap that is closest to the inner peripheral surface of the casing 41 is provided. In regions other than δ, the separation distance between the vent pipe 42 and the inner peripheral surface of the casing 41 is large. Therefore, even if there is some dust intrusion in the casing 41, the rotating operation of the vent pipe 42 is not hindered.

  The gap δ is preferably about 0.2 to 1.0 mm. In this gap δ portion, the pressure adjusting gas introduced into the casing 41 leaks to the steel ball transport tube 22, but if the gap δ is reduced, the damage caused by the steel ball collision in the gap δ portion is an obstacle. There is a risk that the rotating operation will be hindered. Further, when the gap δ is increased, the amount of gas leakage increases, and the flow rate of the steel ball transfer pipe 22 on the downstream side of the valve increases, and the pressure loss increases. Accordingly, if the gap δ is preferably 0.2 to 1.0 mm, the influence of the scratches is eliminated, and the leak amount is several percent or less with respect to the flow rate of the conveying gas, and the pressure loss is not particularly problematic.

  Furthermore, according to the present embodiment, the gap δ eliminates the sealing between the pipe line and the casing 41, but the transfer gas is introduced into the casing 41 through the pressurizing pipe 61 branched from immediately after the discharge port of the blower 23. In this case, a part of the steel ball is introduced directly from the upstream side introduced into the steel ball conveyance line 22, thereby preventing dust accompanying the steel ball 100 from entering the casing 41 from the gap δ. Can do. That is, during execution of shot cleaning, the inside of the casing 41 is pressurized directly by the blower 23 to prevent dust accompanying the steel balls 100 from entering and accumulating in the casing 41. This is because, even if the common blower 23 is used as a gas generation source, the mainstream steel ball transport pipe 22 has a large pressure loss for sending the steel ball 100, so that the pressure from the pressurizing pipe 61 directly connected to the discharge port of the blower 23 can be reduced. This is because the pressure when gas is introduced into the flow path switching valve 4 is high.

DESCRIPTION OF SYMBOLS 1 Boiler 1a Boiler economizer 1b Boiler evaporator 1c Boiler superheater 2 Steel ball tank 21 Rotary feeder 22 Steel ball conveyance pipe 22a One steel ball conveyance pipe 22b after channel selection The other steel ball conveyance after channel selection Pipe 23 Blower 25 Guide chute 26 Steel ball collection device 4 Flow path switching valve 41 Casing 42 Vent pipe 43 Supply nozzle 44 First discharge nozzle 45 Second discharge nozzle 43a Supply nozzle extended pipe end 44a First discharge nozzle Extending pipe end 45a Extending pipe end of second discharge nozzle 5 Pipe shut-off valve 61 Pressurizing pipe δ Gap

Claims (6)

A shot ball conveying device for conveying a shot ball for shot cleaning by airflow, and a pipe connecting the shot ball conveying device and the boiler, each of which is branched in the middle and has a tip opening portion for injecting the shot ball in the boiler. The introduced shot ball transport pipe and a flow path switching valve that is arranged at a branch point of the shot ball transport pipe and selectively switches a branch path for transporting the shot ball from the branch path, and is provided in the boiler. In a shot ball spraying device for shot cleaning that sprays shot balls and removes dust adhering to heat transfer tubes,
The flow path switching valve is
A short cylindrical casing;
A supply port and a plurality of discharge ports formed on the outer peripheral surface of the casing and having a pipe end extending inward from the inner peripheral surface of the casing;
A longitudinal rotation shaft of the casing that brings the discharge port selected from the plurality of discharge ports into communication with the supply port in a state where a gap is interposed between the supply port and the pipe end of the discharge port. A shot ball spraying device comprising a valve body rotatable around. The tips of the pipe ends of the supply port and the discharge port are formed in an R shape along a virtual circle centered on the rotation axis of the valve body,
The distal end portion of the valve body facing the distal ends of the pipe end portions of the supply port and the discharge port with a slight gap is also formed in an R shape along a virtual circle centered on the rotation axis of the valve body The shot ball spraying device according to claim 1, wherein the shot ball spraying device is provided. A pressure pipe is connected to the casing so that the pressure in the casing is higher than at least the pressure in the shot ball transport pipe in the connection portion with the supply port,
3. The shot ball spraying device according to claim 1, wherein a part of the transfer gas from the transfer gas generating device is directly introduced into the shot ball transfer device through the pressurizing tube when performing shot cleaning. .   The leading end opening of each branch path introduced into the boiler is closed with the leading end opening when the channel switching valve is not selected by the flow path switching valve during shot cleaning. The shot ball conveying device according to any one of claims 1 to 3, wherein an open / close lid type shut-off valve for shutting off the communication state is provided.   A boiler provided with the shot ball spraying device according to any one of claims 1 to 4. The shot sphere is air-flow conveyed through the shot sphere conveying pipe introduced into each of the boilers at the front end opening of the branched branch path, and the shot sphere is moved by the flow path switching valve disposed at the branch point of the shot sphere conveying pipe. In the shot sphere spraying method for shot cleaning, which selectively removes the branch path that transports and removes dust adhering to the heat transfer tubes by spraying shot spheres in the boiler from the tip opening of the selected branch path,
A short cylindrical casing, a supply port and a plurality of discharge ports formed on the outer peripheral surface of the casing and having a pipe end extending inward from the inner peripheral surface of the casing, and the supply port and the discharge port It is possible to rotate around the longitudinal rotation axis of the casing that brings the discharge port selected from the plurality of discharge ports into communication with the supply port in a state where a gap is interposed between the tube end portion of the outlet A shot ball spraying method comprising: selectively switching a branch path for carrying a shot ball using a flow path switching valve provided with a valve body.

Images