JP2010260019A - Pulse jet type dust collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy saving type dust collector which suppresses power consumption during filtration of dust by eliminating the pressure loss due to a venturi pipe and prompting dust brush-off effect of the whole bag filter including the vicinity of a bag filter opening to improve the pressure loss. <P>SOLUTION: For being arranged in a high pressure air pipe 2, an air current control means 1 is easily and precisely made to match the center of a nozzle opening hole 2a. The shaft part 1a of the air current control means 1 is controlled to have an outer diameter size (d) smaller than the inner diameter of the nozzle opening hole 2a to form a slit W constant around the complete periphery and compressed air is jetted from the slit W. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a dust wiping device for a pulse jet dust collector including a bag filter.

A main part of a conventional pulse jet dust collector is composed of a plurality of bottomed cylindrical bag filters disposed in a dust-containing chamber and a pulse jet dust removing device provided in a clean chamber. By maintaining the clean chamber at a negative pressure with a blower, an air flow from the dust chamber side to the clean chamber side is generated, and the dust-containing gas taken into the dust collection chamber from the duct on the side of the dust chamber is collected on the outer surface of the bag filter. Is filtered into clean gas, passes through the bag filter cylinder, enters the clean chamber from the bag filter opening, passes through the blower from the outlet of the clean chamber side, and is discharged outside the dust collector. On the other hand, the collected dust blocks the fine air flow path from the outer surface to the inner surface of the bag filter, and gradually increases the pressure loss of the bag filter to increase the negative pressure in the clean room. Depending on the device, it is wiped off at regular intervals or when the negative pressure in the clean chamber reaches a predetermined pressure, accumulates at the bottom of the dust chamber, and is discharged outside the dust collector.

The pulse jet type dust removing apparatus is configured such that high-pressure air pipes having a plurality of nozzle opening holes for ejecting compressed air (0.3 to 0.6 MPa) into a bag filter are arranged in a row at predetermined intervals. Are arranged above the opening of the bag filter at the same interval as the bag filters arranged in the above. Compressed air is injected instantaneously (approximately 0.2 seconds) into the bag filter from the nozzle opening hole, and pulsation is propagated to the bag filter surface to remove dust. In most of the dust collectors, air flow control means such as a venturi tube is disposed at a position communicating with the opening of each bag filter. Due to the ejector effect of the venturi tube, the bag filter surface instantaneously expands to reach the maximum bulge and stops because a secondary gas several times the amount of compressed air injected from the nozzle opening hole is attracted from the venturi periphery. The dust removal effect can be further enhanced by the impact generated at the time and the airflow flowing back from the inside of the bag filter to the outside of the bag filter.

By the way, when the pressure loss of the flow path through which the dust-containing gas and the clean gas pass is large when maintaining the clean chamber of the dust collector at the negative pressure with the blower, the power required for the blower also increases. The main factor of pressure loss is dust adhesion to the bag filter, but the other factor is the pressure loss of the Venturi tube. In a conventional pulse jet dust collector, the venturi tube is formed integrally with a retainer so as to close the bag filter opening. Since the ratio of the inner diameter of the retainer through which the clean gas passes and the inner diameter of the venturi pipe is usually about one-third, the flow rate of the clean gas passing through the venturi pipe during filtration is The pressure loss is proportional to 4 times the flow velocity inside the retainer, and the pressure loss is approximately 16 times. Therefore, even immediately after recovering the pressure loss of the bag filter with the dust wiping device, wasteful blower power, which is essentially unnecessary, is always consumed as compared with a dust collector without a venturi tube. For this reason, a dust collector as in Patent Document 1 has been devised which is a venturi tube which can be swung, and does not cause pressure loss by retracting the venturi tube from the flow path during normal bag filter filtration.

In recent years, bag filters tend to be long for high efficiency in a limited installation area of a dust collector, and there are some having a length of about 9 meters for a retainer diameter of 150 millimeters. In the conventional pulse jet type dust wiping device, in the case of compressed air with a flow velocity of about 90 m / sec, the time required to reach the bottom of the bag filter is about 0.1 seconds in the 9 m bag filter. Half of the injection time of 0.2 seconds is consumed. The compressed air that has reached the bottom of the bag filter and has lost its escape space causes the bag filter to have a positive pressure and expand in the outer circumferential direction. However, it is preferable to keep the bag filter at a positive pressure for as long as possible in order to remove dust. However, as the size of the dust collector increases, the number of bag filters increases. At present, compressed air is injected while the atmosphere in the clean room remains negative. Therefore, the venturi tube ejector effect is used to create a negative pressure around the Venturi tube and perform secondary operation. The function that should attract air into the bag filter does not work sufficiently, and in particular, the positive pressure in the vicinity of the bag filter opening is instantaneously reduced, leaving a portion where pressure loss cannot be recovered. For this reason, an apparatus as in Patent Document 2 has been devised in which a pair of cones are mounted in the vertical direction on a retainer near the bag filter opening. According to Patent Document 2, “the upper end portion of the retainer cone in the longitudinal direction has an upper end contracted portion formed by contracting toward the upper end, so that the filter cloth is disposed on the upper portion of the bag filter retainer during backwashing. When the compressed air is ejected from the nozzle, a part of the compressed air is reflected by the inclined surface of the top contraction portion. In addition, as the angle of the top of the upper end contraction portion of the retainer cone becomes smaller than 65 degrees, the compressed air injected at the time of backwashing becomes difficult to disperse to the outer peripheral side of the retainer cone, and the negative pressure reduction effect tends to be reduced. In other words, there is a tendency that dust is not sufficiently removed at the upper end of the retainer body. This phenomenon has been confirmed from experiments that the body part and the lower end contraction part are provided below the upper end contraction part, so that the airflow on the surface of the upper end contraction part advances toward the trunk part due to the Coanda effect and is difficult to disperse in the outer peripheral direction of the cone. It was. “The (cone) fixing member is preferably a structure and arrangement that does not obstruct the flow of airflow between the retainer main body and the retainer cone, which are (partially omitted) flow paths. (Partially omitted) A rod-shaped member such as a metal wire is arranged radially in the radial direction of the retainer body on the outer periphery of the retainer cone, and the tip thereof is welded to the fixing ring or vertical wire of the retainer body. In the embodiment, the fixing member disposed on the outer periphery of the retainer cone partially blocks the flow of the air current, which is an obstacle to the air flow. The high-pressure air piping that forms the nozzle opening hole must be removed when replacing the bag filter or retainer. However, the air piping is usually connected with a flange, and there is play in the rotation direction, so accurate position repeatability is possible. There is no. In the example of Patent Document 2, the distance between the cone and the nozzle opening hole is long, and it is difficult to visually confirm whether the apex of the cone and the center of the airflow of the compressed air to be injected match.
JP-A-5-329317 JP2008-49341A

The following problems have been clarified from the above prior art.
(1) Conventionally, air flow control means such as a venturi tube and a cone have been manufactured integrally with the retainer, but the strength is durable with the steel wire as the main constituent member of the retainer and the steel plate as the constituent member of the air flow control means. Sex is also different. Each time compressed air is injected, the bag filter repeatedly impacts the retainer and is easily painful, while the venturi tubes that only allow airflow to pass through are less likely to be damaged and their replacement times are inherently different. If a flaw occurred on either side, the entire retainer had to be replaced.
(2) In the device of Patent Document 1, since the venturi tube that can be swung is retracted from the retainer, the pressure loss in the flow path is reduced, but the venturi tube must be swung and retracted by an actuator each time compressed air is injected. Therefore, it is necessary to provide and control the actuator in each array of high-pressure air pipes. Not only is the overall structure of the dust collector complicated and expensive, but there is a problem in maintainability, for example, when individual retainers must be replaced during maintenance, they cannot be removed without removing the entire swing mechanism parts. Arise.
(3) In the case of Patent Document 2, in order to enhance the effect of removing the long bag filter, in order to generate pulsation on the surface of the bag filter, not “a part of the compressed air” but “all the compressed air” is provided on the outer peripheral side. It is preferable from the viewpoint of energy efficiency that it is dispersed into pulsation and converted into pulsation. It is preferable that the angle at the top is smaller than 65 degrees in order to increase the traveling direction energy for sending compressed air to the bottom side of the bag filter. Moreover, the structure which does not obstruct airflow with the fixing member of a cone is preferable.
(4) In the case of Patent Document 2, when the cone and the center of the nozzle opening hole do not coincide with each other, the compressed air is radiated in a partly outer peripheral direction in plan view with respect to the cylindrical axis of the bag filter. In the case of compressed air that is injected in a biased manner, not only the dust dust is biased in a part of the bag filter circumference, but also the pulsation phenomenon that should be generated in the entire circumference of the bag filter is partly biased. In the case of a filter, the pulsation is not derived to the whole, and there is a possibility that the wiping off effect is reduced.
(5) Each time the bag filter injects compressed air, it repeatedly collides with the retainer shockingly and is easily painful. It is impossible to immediately identify which one of the bug filters suspended in the dust chamber is damaged and leaking, and it is not possible to identify individual bugs by removing one of the lids provided for each compartment in the dust collector. An enormous amount of time is spent on visually checking the filter to identify the damaged filter.

The present invention has been made in view of such circumstances,
(1) Reducing the cost of parts and reducing the work time required for parts replacement by separately arranging the air flow control means such as the retainer and the venturi tube or cone,
(2) At the time of filtration of dust-containing gas, secondary air can be attracted by the ejector effect similar to the venturi tube, eliminating the pressure loss of the flow path like the venturi tube,
(3) Reduce the collision angle of the compressed air to the inner periphery of the bag filter to increase the traveling direction energy fed to the bottom of the bag filter, and diffuse all the compressed air to be injected in the outer peripheral direction to generate pulsation energy. Conversion, and the effect of removing in a wide range from the opening to the bottom of the long bag filter increases,
(4) There is no fear of injecting compressed air biased into the bag filter due to misalignment between the airflow control means and the nozzle opening hole, and a uniform airflow film is formed in the vicinity of the opening without blocking the airflow with the fixing member. Increase the effect of maintaining the positive pressure of compressed air,
(5) When a leak occurs in the bug filter, the leak bug filter is detected immediately.
It aims at providing the energy-saving type dust collector which suppresses the power consumption of a blower.

In order to solve the above problems, in the invention described in claim 1 of the present invention, the shaft of the airflow film forming means formed in a horn shape with the uniform shaft portion extending from the top of the vertical shaft cone portion and rising. The core is overlapped with the axis of the nozzle opening hole and engaged or joined to the high-pressure air pipe to form a gap for injecting appropriate compressed air between the outer periphery of the uniform shaft and the inner periphery of the nozzle opening hole. In the dust collector, the conical portion of the airflow film forming means is inserted in the center of the bag filter opening. In addition to joining the uniform shaft portion to the high-pressure air pipe as in the embodiment, the airflow film forming means can be joined to the high-pressure air pipe using a separate joining member.

In the invention described in claim 2 of the present invention, the dust collector is configured such that a sensor is disposed in the airflow film forming means.

In the invention described in claim 1 of the present invention, the airflow film forming means is directly engaged or joined to the high pressure air pipe so that the center of the nozzle opening hole and the airflow film forming means is not displaced. As a result, there is nothing that obstructs the air flow of the fixing member or the like on the outer periphery of the conical portion, so the compressed air injected from the nozzle opening hole collides with the surface of the conical portion, and breaks while diffusing from the axis toward the outer periphery in plan view. Forms a conical airflow film with no air gap. The conical airflow film collides with the inner periphery of the bag filter opening away from the lower edge of the conical portion. The surface of the bag filter expands in a circular shape in plan view by the impinged compressed air, and a step portion, that is, a pulsation is generated between the bag filter and the unexpanded bag filter embedded and contracted in the gap between the vertical lines of the retainer. The pulsation moves instantaneously (approximately 0.1 seconds) toward the bottom of the bag filter, and after the pulsation reaches the bottom, compressed air is injected from the nozzle opening hole for approximately 0.1 seconds. Filled with. Due to the impact of the pulsation propagating on the bag filter surface and the backflow of the air flow from the inside of the bag filter to the outside, the effect of removing dust attached to the outer periphery of the bag filter can be obtained. Further, the conical airflow film acts as if it is covered with compressed air to escape upward from the bag filter opening, and maintains a positive pressure. Since compressed air is injected while forming an appropriate gap between the outer periphery of the uniform shaft portion and the inner periphery of the nozzle opening hole, a conical airflow film is generated by diffusing in the outer peripheral direction at an even density of 360 degrees. For this conical airflow film, the following important findings were made regarding the ejector effect. The incident angle of airflow on the inner periphery of the bag filter is the remaining angle obtained by subtracting the cone angle from 90 degrees, but according to experiments, when the incident angle is 30 degrees or less, the secondary air near the collision part is The ejector phenomenon attracted to the inside was discovered. When the dip angle is 65 degrees and the incident angle is 25 degrees, an even stronger ejector phenomenon increases the overall flow rate of the compressed air, generating pulsations on the bag filter surface and simultaneously expanding the bag filter. The venturi tube is not provided, and a pressure loss due to the reduction of the cross-sectional area of the venturi tube during filtration of the dust-containing gas does not occur, and the removal effect by the ejector effect similar to the venturi tube can be obtained. Even in the conical shape having a reclined angle of 65 degrees (top angle 50 degrees), the compressed air circulates in the direction of the trunk due to the Coanda effect in the cone connecting the trunk as in Patent Document 2 below the cone. The fact that no conical airflow film is formed is described in Patent Document 2 that "if the top angle is smaller than 50 degrees, it is difficult to disperse the compressed air injected during backwashing to the outer peripheral side of the retainer cone". It was confirmed that Since the bag filter surface expands in a circular shape in plan view due to the compressed air, a smooth flow path is formed inside the bag filter. Therefore, the compressed air mainly forms an air flow that flows on the inner peripheral surface of the bag filter and is long. Even a small bag filter is efficiently filled to the bottom. By using the uniform shaft part as an engaging member, the airflow film forming means is arranged in the high-pressure air pipe with the least amount of members, and the bag filter opening without interfering with the airflow of the conical airflow film with the fixed member. Can be interpolated into the part. The pressure loss of the flow path at the position where the airflow film forming means is disposed at the time of filtration is calculated as follows if the ratio of the retainer outer diameter dimension and the diameter of the cylinder of the airflow film forming means is 30%. The rate of decrease is approximately 10 percent and the increase in flow rate is approximately 20 percent. Therefore, the increase in the pressure loss in the flow passage portion is proportional to 44%, and the pressure loss is reduced to about 1/36 compared to the increase of about 1600% in the existing Venturi tube, and the power consumption is less than that in the conventional case. Can operate as a dust collector. During maintenance, the individual retainers can be taken out to the clean chamber side by loosening the connecting bolts of the clean chamber and the fastening bolts (not shown) of the support column and removing the high-pressure air piping as in the conventional procedure. The manufacturing cost is lower because the Venturi tube is not installed.

According to the second aspect of the present invention, in addition to the operation of the first aspect, when one of the many bug filters arranged in the dust collector has a hole and leakage occurs, which bag filter is immediately Since it is possible to detect whether a leak has occurred with the sensor, it is possible to immediately respond to repair work and the like. In the vicinity of the airflow film forming means, clean gas constantly flows upward during the filtration operation of the dust collector, but if the bag filter breaks and leaks, the flow velocity of the airflow changes and heat is taken away from the surface of the cone part Therefore, it is identified that an abnormality has occurred because it differs from the temperature of the sensor disposed in another normal bag filter. In addition to the temperature sensor, the sensor may have applications such as an infrared sensor and a sound sensor.

A preferred embodiment of a pulse jet type dust collector according to the present invention will be described below with reference to FIGS. As shown in FIG. 2, the pulse jet type dust collector 10 is divided into a dust-containing chamber 10 c and a clean chamber 10 d which are partitioned by a partition plate 3. A duct 10a is formed on the side surface of the dust chamber 10c, and an outlet 10b is formed on the side surface of the clean chamber 10d. Further, a plurality of cylindrical bag filters 5 (six in the case of FIG. 2) are arranged in one row in the dust chamber 10c, and a plurality of rows are arranged in a plan view. Compressed air generated by the compressor 20 is stored in a manifold pipe 30 that is cylindrical in the horizontal direction, and a number of diaphragm valves 40 corresponding to each row of the bag filter 5 arranged in the plurality of rows are arranged, and the manifold tube 30 is connected to the pipe. In the clean chamber 10d, a high-pressure air pipe 2 whose front end is closed is arranged at a position orthogonal to the cylindrical axis of the bag filter 5 arranged in a plurality of rows, and the base end of the high-pressure air pipe 2 is connected. The side surface of the clean chamber 10d is passed through the flange 2b and connected to the diaphragm valve 40 by piping. In the middle of the high-pressure air pipe 2, airflow film forming means 1 is provided so as to be inserted into each opening A of the bag filter 5. The dust-containing gas 50 that has passed through the duct 10a is filtered by the bag filter 5 in the dust-containing chamber 10c to become the clean gas 60, and is discharged from the outlet 60 of the clean chamber 10d.

FIG. 1 shows a first embodiment according to the first aspect of the present invention, and shows details of the airflow film forming means 1 in the section XX in FIG. A retainer 4 that holds the bag filter 5 in a cylindrical shape is inserted into the bag filter 5, and is expanded / contracted from the outside by an expansion / contraction band 6 to the cylindrical outer periphery 4 d of the retainer flange base 4 b to engage with each other. The bag filter 5 is inserted into bag filter mounting holes 3 a formed in a large number on the partition plate 3, and the retainer flange base 4 b is fixed with bolts 8. Compressed air 70 is injected from the nozzle opening hole 2 a of the high-pressure air pipe 2 into the bag filter 5 through the airflow film forming means 1. An engagement hole 2 b is formed in the upper section of the high-pressure air pipe 2, and the airflow film forming means 1 is fastened with a bolt 7 to engage. The uniform shaft 1a of the airflow film forming means 1 fitted and suspended in the engagement hole 2b is set to an outer diameter d which is smaller than the inner diameter D1 of the nozzle opening 2a, and is inserted through the center of the nozzle opening 2a. A constant circumferential gap W is formed. The uniform shaft portion 1a hangs downward from the nozzle opening hole 2a at a predetermined distance to form a conical portion 1b. When the ridge angle θ1 of the conical portion 1b is preferably less than 65 degrees and the diameter of the ridge line 1c is 150 mm when the cylindrical diameter of the retainer 4 is 150 mm, the standard is 30% of 45 mm. The creepage distance L from the nozzle opening hole to the ridge line 1c is preferably about 100 mm. FIG. 4 shows the details of the airflow when the compressed air is actually injected in FIG. The bag filter 5 before compressed air injection is contracted to the state D. When the ridge angle θ1 of the conical portion 1b is 65 degrees, the incident angle θ2 of the compressed air is 25. When compressed air of 0.36 MPa is injected at the angle and size, a clear conical airflow film B having a thickness of about 10 to 15 mm is formed in the hatched portion of FIG. 4, and in addition, the shaded portion C is caused by the ejector effect. The flow of air current can be observed.

FIG. 3 shows a second embodiment according to claim 2 of the section XX of FIG. 2, in which the temperature sensor 9 and the wiring 9a are disposed by hollowing the axis of the airflow film forming means 01, The wiring 9a is housed in the wiring duct 121 together with the other wiring 9b.

The present invention is a dust collector that reduces pressure loss in a pulse jet type dust collector, reduces the power consumption of the dust collector, can be used for exhaust gas equipment of various properties such as factories and garbage incinerators, and reduces maintenance costs. It can be used as the invention.

FIG. 2 is a partial enlarged cross-sectional view showing a first embodiment taken along line XX in FIG. The fragmentary sectional view of the dust collector concerning this invention is represented. FIG. 2 is a partial enlarged cross-sectional view showing a second embodiment of the XX line in FIG. It is a partial expanded sectional view in connection with airflow formation of FIG.

DESCRIPTION OF SYMBOLS 1, 11 Airflow film formation means 1a Uniform shaft part 1b Conical part 1c Edge line 2, 12 High pressure air piping 2a Nozzle opening hole 2b Connection flange 2c Engagement hole 3 Partition plate 3a Bag filter attachment hole 4 Retainer 4b Retainer flange base 4d Outer periphery 5 15 Bag filter 6 Expansion band 8 Bolt 10 Dust collector 10a Duct 10b Outlet 10c Dust containing chamber 10d Clean room 20 Compressor 30 Manifold pipe 40 Diaphragm valve 40
50 Dust-containing gas 57 Fixing member 60 Clean gas 70 Compressed air A Bag filter opening d Uniform shaft diameter D1 Nozzle opening hole diameter W Clearance

Claims (2)

Dust-containing gas is filtered through a bag filter, and compressed air is periodically injected from a plurality of nozzle opening holes provided in the high-pressure air pipe to the opening of the bag filter, and dust attached to the outer surface of the bag filter is removed. In the pulse jet type dust collector, an airflow film forming means formed in a horn shape with a uniform shaft portion extending from the top of a conical portion of a vertical shaft center is overlapped on the shaft center of the nozzle opening hole and the high pressure A gap for injecting moderately compressed air is formed between the outer periphery of the uniform shaft portion and the inner periphery of the nozzle opening hole, and the conical portion of the airflow film forming means is formed in the bag filter opening. A pulse jet type dust collector, wherein the dust jet is disposed in the center of the portion. 2. The pulse jet dust collector according to claim 1, wherein a sensor is disposed in the airflow film forming means.