JP2014012234A - Coanda injector foe cleaning bug filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Coanda injector for cleaning a bug filter which can feed a large amount of air or high pressure air from the top of a bag filter toward an opening of an upper surface of the bag filter so as to sufficiently scrape off powder adhered to the external surface of the bag filter when powder in the bag filer is swept off.SOLUTION: There is provided a Coanda injector for cleaning a bag filter which comprises: an annular member having an injection slit for injecting compressed air on the periphery of the inner diameter; and a cylindrical member which is located on the same axis at a lower part of the annular member and feeds amplified air accompanied by air induced from above in primary air to the bag filter. A straight advancing property imparting member for imparting straight advancing property to amplified air fed from the cylindrical member is provided inside the cylindrical member, or the cylindrical member itself is twisted in the longitudinal direction so that a spiral unevenness is provided on the inner wall of the cylindrical member in order to impart straight advancing property to the amplified air.

Description

  The present invention relates to a Coanda injector for cleaning a bag filter, and more particularly to a Coanda injector for cleaning a bag filter for sending amplified air to the bag filter when the powder of the bag filter is swept away.

  Filtration type dust collectors are often used in the process of removing exhaust gas (treated gas) containing powder and discharging it as a clean gas. Bag filters are mainly used for this dust collector. .

A plurality of bag filters formed in a bag shape with a filter cloth are arranged in a casing, and a gas to be treated is passed from the outside to the inside of the bag filter for filtration. The powder contained in the gas to be treated is collected by the bag filter and adheres to the outer surface of the bag filter.
For this reason, it is necessary to periodically sweep off the deposited powder. For example, a technique is known in which a pulse jet is applied to the bag filter from the top of the bag filter through a compressed air tube to sweep the deposited powder. (Patent Documents 1 to 3).

  In the mechanism for causing the pulse jet to act on the bag filter, the pressure is increased by the supply of compressed air from the compressed air source via the on-off valve, and the compressed air is ejected from the ejection hole by the increased pressure. In order to improve the effect of sweeping off the powder adhering to the outer surface of the bag filter, the pressure of the compressed air (static pressure) is increased in as short a time as possible, and the compressed air is blown into the bag filter at once from the blow hole. It was important to improve the effect of the pulse jet.

For this reason, various studies have been conducted in order to make the best use of the effect of the pulse jet. For example, Patent Document 4 describes that a plurality of diaphragm valves are provided for one pulsed air supply pipe.
Further, in Patent Document 5, a space chamber partitioned from an air discharge chamber is provided on the processed air outlet side on the opening side of the filtering member, and a pulse jet nozzle is directed to the opening of the filtering member in the space chamber. And a method in which a pressure fluid is supplied to a nozzle and jetted into the inside of a filtering member is described.
Further, in Patent Document 6, a distal end portion of the proximal end side pipe member is provided with a tapered portion that is reduced in diameter toward the distal end side, and this tapered portion functions as a so-called restrictor. It is described that the flow velocity can be accelerated with a taper and flow from the proximal tube member to the distal tube member.

  On the other hand, an injector for feeding a large amount of air into the bag filter has also been developed. Patent Documents 7 to 10 describe a compressed air injector using an air amplifier using the Coanda effect. Compared with the above method, the powder adhered to the outer surface of the bag filter is wiped off, that is, a bug. Filter cleaning inherently has the advantage of being able to deliver large amounts of air.

  However, none of these technologies has sufficient air volume or air pressure to be sent to the bag filter, and the powder adhering to the outer surface of the bag filter cannot be swept away. In many cases, the filter cloth is clogged and the filter cloth is often replaced. In particular, there was a big problem that the pressure and amount of air reaching the bottom of the bag filter was insufficient.

  Therefore, it has been desired to further develop a device that sends compressed air from the upper surface of the bag filter into the bag filter and efficiently sweeps the powder deposited and deposited on the outer surface of the bag filter.

JP 2002-028425 A JP 2005-125293 A JP 2006000704 A JP 2007-175635 A JP 2008-221106 A JP 2011-050824 A Japanese Patent Laid-Open No. 56-113317 JP 56-113318 A JP-A-56-113319 JP 2008-115847 A

The present invention has been made in view of the above-described background art, and the object of the present invention is to sufficiently sweep off the powder adhering to the outer surface of the bag filter when sweeping the powder of the bag filter. An object of the present invention is to provide an injector capable of sending a large amount of air or air having a high wind speed from above the bag filter toward the upper opening of the bag filter.
In particular, a large amount of air can be instantaneously sent toward the top opening of the bag filter only toward the top opening of the bag filter so that the lower part of the bag filter has the same air pressure and wind speed as the upper part. It is to provide an injector that can.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has made the inner wall structure of the cylindrical member constituting the Coanda injector special so that the bag filter faces inward from the upper surface opening. In addition, a large amount of amplified air amplified with the attraction air by the Coanda effect can be sent out instantaneously with increased straightness, and the powder adhering to the outer surface of the bag filter can be swept away more completely And found the present invention.

That is, by making the inside of the cylindrical member of the Coanda injector specific, the flow of the amplified air is rotated around the traveling direction, thereby giving straightness to the amplified air sent from the cylindrical member. Or, by limiting the flow path of the amplified air flow, it was found that the amount of the amplified air sent from the cylindrical member that was wasted without entering the bottom of the bag filter could be reduced. .
As a result, using a limited amount of primary air injected from the injection slit per unit time, the amplified air obtained by the Coanda effect can be used efficiently, and the powder deposited and deposited on the outer surface of the bag filter, In particular, the present inventors have found that the powder deposited and deposited on the outer surface of the lower part of the bag filter can be efficiently swept away and have reached the present invention.

That is, the present invention is a Coanda injector for cleaning a bag filter for instantaneously sending amplified air from the top to the bag filter at the time of powder cleaning of the bag filter,
(A) an annular member having a connection hole to which compressed air is supplied from a compressed air pipe, and having an injection slit on the circumference of its inner diameter for injecting the compressed air supplied through the connection hole;
(B) A cylinder that is located on the lower coaxial side of the annular member, and sends amplified air accompanied by air attracted from above to the bag filter when primary air is instantaneously injected from the injection slit. Coanda injector for bag filter cleaning consisting of
On the inside of the cylindrical member,
(A) There is provided a straightness imparting member for imparting straightness to the amplified air sent from the lower end of the cylindrical member, or
(B) Coanda for bag filter cleaning, characterized in that the cylindrical member itself is twisted so as to form spiral irregularities in the longitudinal direction on the inner wall of the cylindrical member in order to impart straightness to the amplified air. The injector is provided.

Further, in the present invention, the linearity imparting member is
(A1) A spiral forming member or two or more projecting plate-like members provided inward on the inner wall of the cylindrical member, or
(A2) Provided is the Coanda injector for bag filter cleaning described above, which is a divided plate-like member that divides the inside of the cylindrical member into two or more.

  Further, in the present invention, the inner wall of the cylindrical member forms a Coanda surface at the upper part of the cylindrical member and forms a vertical surface at the lower part. The bag filter cleaning Coanda injector is provided in which the member is provided only on the inner wall portion of the cylindrical member forming the vertical surface.

  The present invention also provides a dust collector characterized in that one of the bag filter cleaning Coanda injectors is installed above each of a plurality of aligned bag filters.

  When the primary air is ejected from the ejection slit, an injector that uses the Coanda effect of sending amplified air from below the injector with the attracting air from above the injector (hereinafter referred to as "Coanda injector") Is very good for bag filter cleaning because it can send out a large amount of air.

According to the Coanda injector of the present invention, the flow of the amplified air that rotates around the axis of the traveling direction of the amplified air can be generated, so that the straightness of the amplified air is increased, or the amplified air passes through the narrow channel. As a result, the straightness of the amplified air increases, and the airflow reaches below the bag filter.
That is, it is possible to suppress the phenomenon that the air pressure does not increase to the lower part of the bag filter by staying only in the upper surface opening of the bag filter, and as a result, the amplified air sent from the Coanda injector can be used without waste.

In addition, according to the present invention, the above-mentioned problems and problems are solved, and when the bag filter powder is swept away, the top of each bag filter is directed to the inside from the top opening of the bag filter and further to the inside. A large amount of air or high pressure or high wind speed air can be sent to the bottom without divergence, so the powder adhering to the outer surface of the bag filter can be sufficiently swept over the entire surface of the bag filter. it can.
A large amount of air, high pressure or high wind speed air can be instantaneously focused and sent out, so that filtration can be continued and powder deposited and deposited on the outer surface of the bag filter can be sufficiently swept away.

According to the Coanda injector for bag filter cleaning of the present invention, a large amount of amplified air obtained by the Coanda effect can be instantaneously sent out toward the upper surface opening of the bag filter located just below it with good straightness. The amplified air enters the inside of the bag filter and further down to the inside of the bag filter, not only can the powder deposited and deposited on the outer surface of the bag filter be efficiently swept away, but also deposited on the outer surface below the bag filter. The powder can also be efficiently removed.
More specifically, according to the Coanda injector for cleaning the bag filter of the present invention, the inner wall of the cylindrical member imparts straightness to the amplified air, and as a result, the amplified air is located below the bag filter located directly below it. Because the target is focused, a large amount of amplified air enters the bag filter.

Usually, the regular filtration operation is temporarily interrupted, and the powder of the bag filter is periodically swept away. However, if the Coanda injector for cleaning the bag filter of the present invention is used, a bug is swept away at one time of powder sweeping. Since the powder deposited and deposited on the outer surface of the filter can be swept away sufficiently efficiently, the frequency of the powder sweeping can be reduced.
Moreover, although a bag filter is replaced | exchanged for the powder which adhered and deposited permanently on the outer surface of a bag filter, this replacement period can be extended, ie, the lifetime of a bag filter can be extended.

It is a side view which shows an example of the dust collector formed by installing the Coanda injector for bag filter cleaning of this invention one by one on the upper part of the bag filter arranged in multiple numbers. It is a top view which shows an example of the dust collector by which the Coanda injector for bag filter cleaning of this invention is installed one by one in the upper part of the bag filter arranged in multiple numbers. It is A-A 'arrow sectional drawing in FIG. It is a B-B 'arrow sectional view in Drawing 1. It is the top view and longitudinal cross-sectional view of the Coanda injector of this invention by which the spiral formation member is provided in the inner wall of a cylindrical member as a rectilinear advance provision member. (A) One spiral forming member forms a single helix for only one period. (B) The two spiral forming members form a double helix for only one period. (C) One spiral forming member forms a single helix for a quarter period (0.25 period). (D) Three spiral forming members form a triple helix for a quarter period (0.25 period). It is the top view and longitudinal cross-sectional view of the Coanda injector of this invention by which the overhang | projection plate-shaped member is provided in the inner wall of the cylindrical member as a rectilinearity provision member. (A) Four projecting plate-like members are provided. (B) Eight overhanging plate-like members are provided. It is the top view and longitudinal cross-sectional view of the Coanda injector of this invention in which the dividing plate-shaped member which divides the inside of a cylindrical member is provided in the inner wall of a cylindrical member as a linear advance provision member. (A) Three divided plate-like members divide the inside of the cylindrical member into three. (B) Six divided plate-like members divide the inside of the cylindrical member into six. It is a longitudinal cross-sectional view of the Coanda injector of the present invention in which the tubular member itself is twisted so as to form spiral irregularities in the longitudinal direction on the inner wall of the tubular member. FIG. 5 is a schematic cross-sectional view illustrating a conventional dust collector in which a bag filter cleaning Coanda injector is not installed, and illustrating powder cleaning of the bag filter. The left side shows the normal operation of the dust collector, and the right side shows the dust sweeping time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified within the scope of the present invention. .

<Dust collector with bag filter and powder sweep of bag filter>
FIG. 9 shows a longitudinal sectional view of a dust collector 11 in which a plurality of general bag filters 12 are mounted, although the bag filter cleaning Coanda injector 2 of the present invention is not installed. In FIG. 9, four bag filters 12 are drawn.
The left side of FIG. 9 (two bag filters) shows a steady filtration state in which the gas to be treated is filtered by the bag filter 12. The gas to be treated is passed from the outside to the inside of the bag filter 12 and the powder contained therein is filtered. The powder contained in the gas to be treated is collected by the bag filter 12 and deposited on the outer surface of the bag filter 12.

Adhering and depositing powder has an adverse effect on filterability, so it must be periodically swept away. On the right side of FIG. 9 (two bag filters), a pulse jet is fed into the bag filter 12 from the upper part of the bag filter 12 through the compressed air tube 4 and the powder deposited and deposited on the outer surface of the bag filter 12 is swept away. It shows the state of going.
In FIG. 9, the regular filtration state and the powder sweep state of the outer surface of the bag filter 12 are separated by the shutter, and the dust collector 11 is partially divided in the regular filtration operation. Thus, the powder sweeping state is inserted periodically in order.

<Coanda injector for bag filter cleaning>
The Coanda injector 2 for cleaning the bag filter of the present invention is for instantaneously sending the amplified air 23 from above to the bag filter 12 when the powder of the bag filter 12 is swept away.
The Coanda injector 2 for cleaning a bag filter according to the present invention has an upper surface of the bag filter 12 without causing a large amount of air or high-pressure air to diverge around when “powder sweeping” is periodically inserted. Therefore, the powder adhering and depositing on the outer surface of the bag filter 12 can be sufficiently swept off.
Hereinafter, “Bag filter cleaning Coanda injector 2” may be simply abbreviated as “Coanda injector 2”.

FIG. 1 and FIG. 2 show an example in which the Coanda injector 2 of the present invention is installed above each bag filter 12 so that the amplified air 23 can be sent out toward the upper surface opening of the bag filter 12.
One Coanda injector 2 of the present invention, which will be described later, is installed on each of the upper parts of the plurality of aligned bag filters 12 to form the dust collector 11.

  In FIG.1 and FIG.2, it is the side surface of the cylindrical member 8 which comprises the Coanda injector 2, and the one side of the annular member 6 which comprises the Coanda injector 2 has one compressed air pipe 4 installed horizontally. In addition, only one auxiliary member 5 to which the compressed air X does not flow is provided below the other side of the annular member 6.

In the compressed air pipe 4, the slit width of the injection slit 7 is sufficiently small and the rate is limited, so that only one air is sufficient as the amount of air. Therefore, there is no need to install an extra compressed air pipe. The book configuration is preferred. However, two compressed air tubes 4 may be provided in parallel on the side surfaces of the cylindrical member 8 and on both sides of the annular member 6.
Moreover, since the compressed air pipe 4 can be installed below the annular member 6, the height position of the compressed air pipe 4 of the existing dust collector 11 that does not use the Coanda injector can be used as it is, and replacement is easy. Although it is preferable, the compressed air pipe 4 may be provided on the upper side instead of the lower side of the annular member 6.

Pulsed compressed air X is supplied from the compressed air pipe 4 to the annular member 6 through the connection hole 3 opened in the lower part of the annular member 6 of each Coanda injector 2.
FIG. 3 is a cross-sectional view taken along the line AA ′ in FIG. 1, and is a cross-sectional view of the compressed air pipe 4 that passes through one Coanda injector 2 and its side surface and supplies the compressed air X to the annular member 6. It is.
The air supplied in a pulse form from the compressed air pipe 4 to the annular member 6 through the connection hole 3 is instantaneously injected as primary air 21 from the injection slit 7 provided on the inner diameter side of the annular member 6. ing.

  As shown in FIGS. 3 and 4, the Coanda injector 2 for cleaning bag filters of the present invention has “a connection hole 3 to which compressed air X is supplied from the compressed air pipe 4, and is supplied through the connection hole 3. The annular member 6 having the injection slit 7 for injecting the compressed air X on the circumference of the inner diameter thereof, and “the primary air 21 is instantaneously injected from the injection slit 7 which is located on the lower coaxial side of the annular member 6. In this case, the primary air 21 includes a cylindrical member 8 ”that sends the amplified air 23 accompanied by the attraction air 22 from above to the bag filter 12.

The annular member 6 has a donut shape, and an injection slit 7 exists on the inner diameter side of the annular member 6 toward the center of the donut shape (see FIGS. 3 and 4).
The annular member 6 has a connection hole 3 to which the compressed air X is supplied from the compressed air pipe 4. In FIG. 3 to FIG. 8, one connecting hole 3 exists in each annular member 6 at the lower part of the annular member 6, which is a preferable mode. The connection hole 3 may exist in the upper part of the annular member 6, but when the existing device is replaced with the Coanda injector 2, it is unnecessary to change the upper and lower positions of the existing compressed air pipe 4. The connection hole 3 is preferably in the lower part of the annular member 6.
Two or more connecting holes 3 may exist in each annular member 6, but even if only one connecting hole 3 is present, sufficient compressed air X can be instantaneously supplied to the annular member 6. Is preferable in that it becomes unnecessary.

The inner diameter of the annular member 6 is determined by the size of the bag filter 12 to be cleaned and is not particularly limited, but is usually 30 mm to 300 mm, preferably 50 mm to 200 mm, and particularly preferably 70 mm to 150 mm.
The annular member 6 is preferably shaped like a substantially circular cylinder rounded into a donut shape, but the inner diameter of the substantially circular cylinder is also determined by the size of the bag filter 12 and the like, but is not particularly limited, but is usually 7 mm to 100 mm, preferably The thickness is 10 mm to 60 mm, particularly preferably 15 mm to 35 mm.

The optimum value of the average width of the injection slit 7 is determined depending on the amount and pressure of the compressed air X, the diameter of the annular member 6 and the like, but is preferably 0.1 mm to 1 mm, more preferably 0.2 mm to 0.6 mm. Preferably, 0.3 mm to 0.4 mm is particularly preferable.
When the average width of the injection slit 7 is too large, the wind speed of the primary air 21 cannot be secured, the amount of the attraction air 22 is reduced, the sufficient amplified air 23 is not sent out, and the powder filter of the bag filter 12 is sufficiently swept away. On the other hand, if the slit width is too small, the Coanda effect cannot be utilized to the maximum, and the powder may not be sufficiently swept away when the bag filter 12 sweeps the powder.

The “Coanda surface” is bent downward from a substantially horizontal plane so that the primary air 21 ejected from the ejection slit 7 descends along the surface, and the primary air 21 descends along the surface. Sometimes, it refers to a surface that can be sent downward as amplified air 23 with the attraction air 22 from above. The Coanda effect is exhibited when primary air flows along the Coanda surface. The “Coanda surface forming body 9” is a forming body whose surface is a Coanda surface and exists on the upper part of the tubular member 8.
The supplied compressed air X is injected as primary air 21 from the injection slit 7, bends along the surface of the Coanda surface forming body 9, is turned in the axial direction (downward), and descends the cylindrical member 8. Since the primary air 21 has a high flow velocity, it has a very low pressure determined from Bernoulli's theorem. Accordingly, air is drawn from above the Coanda injector 2 and is sent downward as amplified air 23 with the attraction air 22.

  Below the annular member 6, there is a cylindrical member 8 that shares the central axis of the annular member 6. When the powder of the bag filter 12 is swept away, the primary air 21 is instantaneously ejected from the ejection slit 7, but the tubular member 8 is amplified air 23 composed of the primary air 21 and the attraction air 22 from above. Can be sent out below the Coanda injector 2 toward the upper surface of the bag filter 12. That is, the cylindrical member 8 can send out the amplified air 23 from the upper surface of the bag filter 12 to the inside without allowing the amplified air 23 to be diffused in all directions. It has become.

  The length and diameter of the cylindrical member 8 are appropriately adjusted according to the speed and amount of the primary air 21, the distance from the porous plate 13, the size of the bag filter 12, and the like. Further, the shape of the tubular member 8 on the outlet side can be changed to an optimum shape according to the shape and situation of the bag filter 12.

The inner diameter of the tubular member 8 is determined by the speed and amount of the primary air 21 and the size of the bag filter 12 to be cleaned, but is not particularly limited, but is usually 20 mm to 250 mm, preferably 40 mm to 200 mm, particularly preferably 60 mm. ~ 150 mm.
The inner diameter of the cylindrical member 8 is preferably smaller than the donut-shaped inner diameter of the annular member 6 by 7 mm to 40 mm, more preferably 10 mm to 30 mm, and particularly preferably 15 mm to 25 mm. Half of the difference in diameter corresponds to the lateral width of a circumferential Coanda surface forming body 9 described later.

<Straightness imparting member and twist that can form spiral irregularities on the cylindrical member itself>
The Coanda injector 2 of the present invention has an inside of the tubular member 8,
(A) Is there a rectilinearity imparting member for imparting rectilinearity to the amplified air 23 delivered from the lower end of the cylindrical member 8 (specific examples are shown in FIGS. 5 to 7), or
(B) In order to impart straightness to the amplified air 23, the tubular member 8 itself is twisted so that a spiral unevenness 34 is formed in the longitudinal direction on the inner wall of the tubular member 8 (a specific example is shown in the figure). (Shown in 8)
It is characterized by that.

In addition, the straightness imparting member of (a) is
(A1) A spiral forming member 31 (specific example is shown in FIG. 5) or two or more projecting plate-like members 32 (specific example in FIG. 6) provided inward on the inner wall of the cylindrical member 8 Show),
Or
(A2) A dividing plate member 33 (a specific example is shown in FIG. 7) that divides the inside of the cylindrical member 8 into two or more is preferable.

As described above, the cylindrical member 8 is configured to be able to send the amplified air 23 to the lower side of the Coanda injector 2 without dissipating the amplified air 23 in the four directions. If b) is not applied, the amplified air 23 sent out from the tubular member 8 may lack straightness, and the amplified air 23 is diffused in all directions immediately after leaving the tubular member 8. There were cases where there were many. Even if all of the amplified air 23 enters the bag filter 12, it may not reach the lower part of the bag filter 12 due to lack of straightness.
The Coanda injector 2 according to the present invention has the above-described (a) or (b) on the inner side of the tubular member 8, thereby imparting rectilinearity to the amplified air 23 sent out from the tubular member 8, which is wasted. Amplified air 23 can be fed into the bag filter from the upper opening of the bag filter, and a large amount of air, high-pressure air, or high wind speed air can be fed to the bottom of the bag filter 12.

In order to give straightness to the amplified air 23 sent out from the tubular member 8, the path of the amplified air 23 in the tubular member 8 is provided by a straightness imparting member such as the overhanging plate member 32 and the dividing plate member 33. (A specific example is shown in FIGS. 6 and 7), or a method in which the flow of the amplified air 23 is rotated about the direction of the flow as a rotation axis so that the flow is not dissipated far away ( Specific examples are shown in FIGS. 5 and 8.
As the latter “method of rotating the flow of the amplified air 23”, a method of providing the spiral forming member 31 on the inner wall of the cylindrical member 8 (a specific example is shown in FIG. 5), twisting the cylindrical member 8 itself, There is a method (a specific example is shown in FIG. 8) or the like for forming spiral irregularities 34 in the longitudinal direction on the inner wall of the cylindrical member 8.

In any of the spiral-shaped unevenness 34 formed on the inner wall of the cylindrical member 8 by twisting the spiral forming member 31, the projecting plate-shaped member 32, the dividing plate-shaped member 33, and the cylindrical member 8 itself, There is no particular limitation as long as the amplifying air 23 can be given straightness, only in the upper part of the cylindrical member 8, only in the central part, only in the lower part, only in the upper part and the central part, only in the central part and the lower part. Any of these may be used.
However, since the Coanda effect is reduced, it is preferable that none of the above exist on the uppermost Coanda surface forming body 9 of the tubular member 8. That is, it is preferable that the overhang plate member 32 or the divided plate member 33 is provided only on the inner wall portion of the cylindrical member 8 forming a vertical surface.

  Further, in any of the spiral forming member 31, the projecting plate-like member 32, and the “spiral unevenness 34 formed on the inner wall of the tubular member 8 by twisting the tubular member 8 itself”, the inner side of the tubular member 8. The “overhang width and the height of the projections and depressions 34” (H) toward the surface are not particularly limited as long as the amplifying air 23 can be given straightness, and also depends on the inner diameter of the cylindrical member 8, but is 5 mm to 50 mm is preferable, 10 mm to 40 mm is more preferable, and 15 mm to 30 mm is particularly preferable.

In addition, the ratio of the above-mentioned “projection width toward the inside of the cylindrical member 8 and the height of the unevenness 34” (H) to “half the inner diameter (inner radius) of the cylindrical member 8” (R) There is no particular limitation as long as it can impart straightness to the amplified air 23, but H / R = 1/6 to 6/6 is preferable, 1.5 / 6 to 4/6 is more preferable, and 2/6 to 3/6 is preferable. Particularly preferred.
H / R = 6/6 means that “spiral forming member 31” and “spiral unevenness 34 formed on the inner wall of the cylindrical member 8 by twisting the cylindrical member 8 itself” are those from the left and right. In the overhanging plate-like member 32, the overhanging plate-like member 32 collides with the center to become a divided plate-like member 33.

<< Spiral forming member >>
The spiral forming member 31 may be a single helix as shown in FIGS. 5 (A) and 5 (C), a double helix as shown in FIG. 5 (B), as shown in FIG. 5 (D). A triple helix or a further overlapping helix may be used, but a single helix to a hexahelix is preferred, a double helix to a quadruple helix is preferred, and a double helix to a triple helix is particularly preferred.

The “spiral forming member 31” and “spiral unevenness 34 formed on the inner wall of the cylindrical member 8 by twisting the cylindrical member 8 itself” rotate about the traveling direction of the amplified air 23 as an axis. Since the amplified air 23 can flow, the straightness of the amplified air 23 increases.
“The flow of the amplified air 23 rotating around the axis about the traveling direction” means that the flow velocity vector is v, and the rot (rotation) of v is not 0, that is, the vorticity is not 0. Say.

The speed of rotation of the amplified air flow is the amplification sent from the inner diameter of the cylindrical member 8 (ie, the diameter of the flow of the amplified air 23) and the lower end of the Coanda injector 2 (ie, the lower end of the cylindrical member 8) of the present invention. From the velocity of the air 23 in the traveling direction, an optimum value is inevitably derived hydrodynamically.
In order to obtain a rotational speed as close as possible to the optimum value of the rotational speed, the pitch of the spiral forming member 31 is set to the length of the cylindrical member 8 in consideration of ease of manufacture and a realistic structure. The period of entering (height) is preferably 0.01 period to 2 periods, more preferably 0.03 period to 1.4 periods, and particularly preferably 0.1 period to 1 period.

  If the pitch is too coarse, the amplified air 23 may not rotate sufficiently. On the other hand, if the pitch is too small, the amplified air 23 strikes the spiral forming member 31 at an angle close to the vertical, so that the speed of the amplified air 23 is increased. May become slow.

  FIG. 5 (A) shows a case where one spiral forming member 31 forms a single helix for one period between the lengths (heights) of the cylindrical member 8, and FIG. FIG. 5C shows a case where two spiral forming members 31 form a double helix for only one period between the lengths (heights) of the cylindrical member 8, and FIG. 5C shows one spiral forming member. 31 shows a case where a single helix is formed by a quarter period (0.25 period) between the lengths (heights) of the cylindrical member 8, and FIG. 5D shows the formation of three spirals. The case where the member 31 forms a triple helix for a quarter period (0.25 period) between the lengths (heights) of the cylindrical member 8 is shown.

<< overhang plate member >>
Two to 64 projecting plate-like members 32 as shown in FIGS. 6 (A) and 6 (B) are preferably provided on the inner wall of the cylindrical member 8, and three to 32 are provided. It is more preferable that 4 to 16 are provided. If the amount is too small, it may not be possible to sufficiently impart straightness to the amplified air 23. On the other hand, if the amount is too large, the speed of the amplified air 23 may be reduced.

<< Parting plate-like member >>
7 to 32 are preferably provided on the inner wall of the tubular member 8 as shown in FIGS. 7A and 7B, and preferably 3 to 16 are provided. Is more preferable, and it is particularly preferable that 4 to 8 are provided. If the amount is too small, it may not be possible to sufficiently impart straightness to the amplified air 23. On the other hand, if the amount is too large, the speed of the amplified air 23 may be reduced.
In addition, the one dividing plate-shaped member 33 means the thing from the inner wall of the cylindrical member 8 to the center. Therefore, in FIG. 7A, there are three divided plate members 33, and in FIG. 7B, there are six divided plate members 33.

<< Torsion of tubular member itself >>
FIG. 8 shows that the cylindrical member 8 itself is twisted so as to form a spiral irregularity 34 in the longitudinal direction on the inner wall of the cylindrical member 8 in order to impart straightness to the amplified air 23. This is an embodiment of the Coanda injector 2.
The pitch of the “spiral irregularities 34 formed on the inner wall of the cylindrical member 8 by twisting the cylindrical member 8 itself” is to obtain a rotational speed as close as possible to the optimum value of the rotational speed determined hydrodynamically. In consideration of ease of manufacture, realistic structure, etc., 0.3 to 2 laps are preferable per length (height) of the tubular member 8, and 0.4 to 1.5 laps are more preferable. 0.5 to 1 round is particularly preferable. The pitch shown in FIG. 8 is a preferable example.

<Dust collector>
The dust filter 11 is configured by installing one Coanda injector 2 for cleaning the bag filter according to the present invention above each of the plurality of aligned bag filters 12. In FIGS. 1 and 2, only one column is illustrated, but usually, the dust collector 11 is configured by arranging several to several hundreds vertically and horizontally.

The distance between the lower end of the tubular member 8 and the upper end of the bag filter is usually 50 mm to 300 mm, preferably 60 mm to 240 mm, and particularly preferably 70 mm to 160 mm.
When the Coanda injector 2 of the present invention is used, the straightness of the amplified air 23 is increased, so that even if the distance is large, the powder adhering to the inner wall (lower part) of the bag filter can be sufficiently removed.

In operation of the dust collector 11, the powder of the bag filter 12 is periodically swept away. However, if the Coanda injector 2 of the present invention is used, the powder deposited and deposited on the outer surface of the bag filter 12 at the time of one powder sweeping. Since the body can be swept away sufficiently efficiently, the routine filtration operation can be temporarily suspended to reduce the frequency of powder sweeping.
Further, the bag filter 12 is periodically replaced because of the powder that has permanently adhered to and accumulated on the outer surface of the bag filter 12. However, if the Coanda injector 2 of the present invention is used, such replacement time is extended. The life of the bag filter 12 can be extended.

  Hereinafter, the present invention will be described more specifically with reference to the drawings. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Example 1
A Coanda injector composed of the annular member and the cylindrical member shown in FIGS.
The annular member has a donut shape with an outer diameter of 167 mm and an inner diameter of 97 mm, the cylindrical member has an inner diameter of 80 mm and a length of 97 mm, and the annular member and the cylindrical member are integrated to produce a Coanda injector.

The straightness imparting member was evaluated as follows.
(A) The spiral forming member is shown in FIG.
That is, a triple helix having a pitch of 1/4 (= 0.25) [period] / [length of cylindrical member] and a width of 10 mm was evaluated. This is referred to as “injector A”.
(B) The protruding plate member is shown in FIG.
That is, four overhanging plate members, a width of 25 mm, a length of 70 mm, and a cylindrical member excluding the Coanda surface were evaluated. This is referred to as “injector B”.
(C) The divided plate-like member is shown in FIG.
In other words, the evaluation was made on six divided plate-like members, 70 mm in length, and provided over almost the entire length of the cylindrical member excluding the Coanda surface. This is referred to as “injector C”.

(D) FIG. 8 shows that the cylindrical member itself is twisted so as to form spiral irregularities in the longitudinal direction on the inner wall of the cylindrical member.
That is, the pitch of “spiral unevenness formed on the inner wall of the cylindrical member by twisting the cylindrical member itself” is 0.1 period per length (height) of the cylindrical member. A height of 5 mm was evaluated. This is referred to as “injector D”.

(Q) A straight advanceability imparting member was not provided, and the cylindrical member itself was not twisted. Other than that is the same as the injectors A to D described above. This is referred to as “injector Q”.

100 L of compressed air was supplied into the annular member from the connection hole at a pressure of 3 kgf / cm ² from the compressed air tube per second.
The amount of amplified air sent downward from the cylindrical members of the Coanda injectors A to D and Q is 20 mm below, 500 mm below and 1000 mm below from the lower end of the Coanda injector (lower end of the cylindrical member). The wind speed was measured using a general-purpose anemometer.

  As a result, all of the injectors A to D were able to obtain a sufficient wind speed even when the distance from the lower end of the injector was long. In the injector Q, a sufficient wind speed was obtained at a location 20 mm from the lower end of the injector. When the distance was increased, sufficient wind speed could not be obtained.

  The Coanda injector of the present invention feeds amplified air having straightness to the bag filter when the powder is swept away from the bag filter, and can be widely used in the field of removing powder from gas. It is also used when introducing a new dust collector or replacing an existing injector part.

DESCRIPTION OF SYMBOLS 2 Coanda injector for bag filter cleaning 3 Connection hole 4 Compressed air pipe 5 Auxiliary member 6 Annular member 7 Injection slit 8 Cylindrical member 9 Coanda surface formation body 11 Dust collector 12 Bag filter 13 Perforated plate 21 Primary air 22 Attracting air 23 Amplified air 31 Spiral forming member 32 Overhang plate member 33 Dividing plate member 34 Spiral irregularities X Compressed air

Claims (4)

A Coanda injector for cleaning the bag filter for instantaneously sending the amplified air from the top to the bag filter when sweeping the powder of the bag filter,
An annular member having a connection hole through which compressed air is supplied from the compressed air pipe and having an injection slit on the circumference of its inner diameter for injecting the compressed air supplied through the connection hole; A coanda for bag filter cleaning comprising: a cylindrical member that sends amplified air accompanied by air attracted from above to the primary air when primary air is instantaneously jetted from the jet slit. An injector,
A rectilinearity imparting member for imparting rectilinearity to the amplified air sent from the lower end of the cylindrical member is provided inside the tubular member, or in order to impart rectilinearity to the amplified air, A Coanda injector for cleaning a bag filter, characterized in that the tubular member itself is twisted so as to form spiral irregularities in the longitudinal direction on the inner wall of the tubular member.   The rectilinearity imparting member divides a spiral forming member, two or more projecting plate-like members, or the inside of the tubular member into two or more, which are provided inwardly on the inner wall of the cylindrical member. The Coanda injector for bag filter cleaning according to claim 1, wherein the bag filter is a divided plate member.   The inner wall of the cylindrical member forms a Coanda surface at the upper part of the cylindrical member and forms a vertical surface at the lower part, and the overhanging plate member or the divided plate member is the vertical surface. The Coanda injector for bag filter cleaning according to claim 1 or 2, wherein the coanda injector is provided only on an inner wall portion of a cylindrical member forming the tube.   The Coanda injector for bag filter cleaning according to any one of claims 1 to 3, wherein each one is installed on top of a plurality of aligned bag filters. Dust collector.

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