JP2014138936A - Coanda injector for 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 filter 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. The shape of the injection slit is designed to inject the primary air downward from a horizontal surface.

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 the exhaust gas (treated gas) containing powder and discharging it as a clean gas, but bag filters are mainly used for this dust collector. .

A plurality of bag filters formed in a bag shape with a filter cloth are disposed 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 6).

  However, in an injector for causing a pulse jet to act on the bag filter, the pressure is increased only 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 pressure increase. Therefore, in order to improve the effect of sweeping off the powder adhering to the outer surface of the bag filter, the amount of compressed air is increased in as short a time as possible, and air is blown into the bag filter from the jet hole, and the effect of the pulse jet It was important to improve.

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 7 describes that a plurality of diaphragm valves are provided for one pulsed air supply pipe.
Further, in Patent Document 8, a space chamber partitioned from an air discharge chamber is provided on the opening side of the filtration member on the opening side of the filtration member, and a pulse jet nozzle is directed to the opening of the filtration 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 9, a distal end portion of the proximal end side pipe member having a diameter that decreases toward the distal end side is provided, and this distal end functions as a so-called throttle. 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, Patent Documents 10 to 13 describe a compressed air injector using an air amplifier using the Coanda effect.
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 replaced. In particular, the pressure of the air reaching the bottom of the bag filter was insufficient.

  Therefore, it has been desired to further develop a device for sending compressed air from above the bag filter into the bag filter and efficiently sweeping the powder deposited and deposited on the outer surface of the bag filter.

JP 2002-028425 A JP 2003-220314 A JP 2005-125293 A JP 2006-305400 A JP 2006000704 A JP 2005-288278 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 the top of the bag filter toward the upper opening of the bag filter.
In particular, an object of the present invention is to provide an injector capable of instantaneously sending a large amount of air toward the upper opening of the bag filter so that the lower part of the bag filter has the same air pressure as the upper part.

When the primary air is ejected from the ejection slit, an injector that utilizes the Coanda effect of sending amplified air from the other of the injectors with the attracting air from one of the injectors (hereinafter referred to as “Coanda injector”) Is very good for bag filter cleaning because it can send out a large amount of air.
In particular, the present invention is to provide a Coanda injector for cleaning a bag filter capable of instantaneously sending a larger amount of air toward the upper opening of the bag filter in the Coanda injector.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has made the shape of the injection slit of the Coanda injector specific so that more primary air is injected from the injection slit. It can be accompanied by attracting air, and as a result, a large amount of amplified air can be instantaneously sent out toward the opening of the upper surface of the bag filter, and the powder adhering to the outer surface of the bag filter can be swept away more completely. As a result, the present invention has been found.

  In other words, by making the shape of the injection slit of the Coanda injector specific, it is possible to inject a lot of primary air in a specific direction, and the amount of primary air that is unnecessarily injected without attracting air is reduced. Relatively reduced, limited amount of primary air injected from the injection slit per unit time can be efficiently used for air amplification, and as a result, the powder deposited and deposited on the outer surface of the bag filter is efficiently As a result, the present invention was found.

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,
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,
The annular member includes an annular member lower part and an annular member upper part, and the annular member lower part and the tubular member are integrated via a Coanda surface forming body,
The shape of the injection slit formed with the upper part of the inner diameter side annular member positioned on the inner diameter side of the upper part of the annular member as the upper part of the injection slit and the Coanda surface forming body as the lower part of the injection slit causes the primary air to be injected downward from the horizontal plane. The present invention provides a Coanda injector for bag filter cleaning, which is characterized by the above.

  The present invention also provides a bag filter main body characterized in that one Coanda injector for cleaning the bag filter is provided on each of a plurality of aligned bag filters. is there.

  Further, the present invention changes the relative position of the lowest point or rising point of the upper part of the inner diameter side annular member with respect to the uppermost point of the Coanda surface forming body, or on the inner side of the upper part of the inner diameter side annular member. A bent primary air guide ring is provided, and the shape of the injection slit is set so that the amount of amplified air delivered to the bag filter per unit time is more than twice the amount of primary air injected per unit time. The manufacturing method of the Coanda injector for bag filter cleaning as described in any one of Claims 1 thru | or 3 is provided.

  According to the present invention, the above-mentioned problems and problems are solved, and a large amount of air or high-pressure air is blown from the top of each bag filter toward the top surface opening of the bag filter when the powder of the bag filter is swept away. Since it can be sent out, the powder adhering to the outer surface of the bag filter can be sufficiently swept away. In addition, since a large amount of air or air having a high wind speed can be sent out instantaneously, the powder deposited and deposited on the outer surface of the bag filter can be completely swept off by continuing filtration.

  According to the Coanda injector for cleaning the bag filter of the present invention, the Coanda effect is sufficiently exerted, that is, the amount of the amplified air with respect to the primary air can be increased, so that a large amount of the amplified air is instantaneously positioned directly below the bug. It can be sent out to the filter, and the powder deposited and deposited on the outer surface of the bag filter can be efficiently swept away.

More specifically, according to the Coanda injector for bag filter cleaning of the present invention, since the injection slit has a specific shape, a large amount of primary air can be injected below the horizontal plane, resulting in the Coanda surface. Since the amount of primary air flowing along the pipe increases, it is possible to efficiently carry the induced air, and it is possible to send a larger amount of amplified air to the bag filter located immediately below.
In other words, the amount of wasted primary air that does not flow along the Coanda surface (does not move down along the Coanda surface) is relatively reduced while being horizontally injected, and the amount that is injected from the injection slit per unit time is relatively reduced. A given amount of primary air can be efficiently used for air amplification, and as a result, a large amount of amplified air can be delivered.
In addition, the primary air which does not fall along the Coanda surface while being injected horizontally cannot be accompanied by the attraction air from the upper part, and cannot send out the amplified air.

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 bag filter main body by which the Coanda injector for bag filter cleaning of this invention is installed one by one on the upper part of the bug filter which aligned. It is a top view which shows an example of the bag filter main body by which the Coanda injector for bag filter cleaning of this invention is installed one by one on the upper part of the bug filter which arranged. It is A-A 'arrow sectional drawing in FIG. It is a B-B 'arrow sectional view in Drawing 1. It is an expanded sectional view of the annular member and injection slit of the left side of FIG. It is an expanded sectional view of D section of Drawing 5. (1) It is a figure which shows the shape of the injection slit in which the lowest point of the upper part of the inner diameter side annular member is directly above the highest point of the Coanda surface forming body. (2)-(4) is a view showing the shape of an injection slit in which the lowest point of the upper part of the inner diameter side annular member is located on the center side (right side) of the annular member by d from the highest point of the Coanda surface forming body ( D increases from (2) to (4)). It is a figure which shows the shape of the injection slit in which the primary air guide ring bent downward is provided in the further inner side of the annular member upper part on the inner diameter side. FIG. 6 is a schematic cross-sectional view illustrating a conventional bag filter body in which a bag filter cleaning Coanda injector is not installed, and illustrating powder cleaning of the bag filter. The left side shows normal operation of the bag filter body, and the right side shows powder sweep-off.

  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. .

FIG. 8 is a longitudinal sectional view of a general bag filter main body 11 in which a plurality of bag filters are mounted, although the bag filter cleaning Coanda injector 2 of the present invention is not installed. In FIG. 8, four bug filters are drawn.
The left side (two bag filters) in FIG. 8 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.

For this reason, the deposited and deposited powder has an adverse effect on the filterability, so it must be periodically swept off. On the right side of FIG. 8 (two bag filters), a pulse jet is sent 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. 8, a steady filtration state (two on the left side) and a sweeping state of powder on the outer surface of the bag filter 12 (two on the right side) are separated by a shutter. Thus, the powder sweep state is partially inserted.

The Coanda injector for bag filter cleaning 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 for bag filter cleaning of the present invention instantaneously sends a large amount of air or high-pressure air from the upper surface of the bag filter 12 to the inside when “powder sweeping” is periodically inserted. Therefore, the powder adhered and deposited on the outer surface of the bag filter 12 can be sufficiently swept away.
Hereinafter, the “Coanda injector for cleaning the bag filter” may be simply abbreviated as “Coanda injector”.

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 “a plurality of aligned bug filters 12” to form the bag filter body 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.
Although the above-described configuration is preferable, two compressed air pipes 4 may be provided in parallel on both sides of the annular member 6 on the side surface of the cylindrical member 8. You may be laid horizontally on the upper side instead of the lower side.

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 for bag filter cleaning according to the present invention has “the connection hole 3 to which the compressed air X is supplied from the compressed air pipe 4, and the compression supplied through the connection hole 3. The annular member 6 having the injection slit 7 for injecting the 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 is formed with a cylindrical member 8 ”that sends the amplified air 23 accompanied by the air 22 attracted 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 5).
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. 5, one connection 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. However, when the existing device is replaced with a Coanda injector, the connection work is not necessary because the work for changing the vertical position of the existing compressed air pipe 4 is unnecessary. The 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. One is preferable at the point which 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.

  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 downward from below the Coanda injector 2 toward the upper surface of the bag filter 12. That is, the cylindrical member 8 can send the amplified air 23 downward from the Coanda injector 2 without diffusing the amplified air 23 in all directions. It has come to include.

  The length (height) of the cylindrical member 8 is 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 the Coanda surface forming body 9 provided along the circumference.

As shown in FIG. 5, the annular member 6 includes an annular member lower part 6 b and an annular member upper part 6 a, and the annular member lower part 6 b and the tubular member 8 are integrated via a Coanda surface forming body 9. ing.
The annular member lower portion 6b and the annular member upper portion 6a are caulked on the outer peripheral side in FIG. 5, but the connection on the outer peripheral side is not particularly limited and may be integrated.

  The donut-shaped inner peripheral side (center side) of the annular member lower part 6b is a Coanda surface forming body 9, and the Coanda surface forming body 9 faces the annular member 6 side (left side in FIGS. 5 and 6). The other side (right side in FIGS. 5 and 6) of the Coanda surface forming body 9 is gradually bent downward to become vertical, and the cylindrical member below the other 8 are connected together.

The Coanda surface formation body 9 is a formation body whose surface is bent so as to exhibit the Coanda effect (from the left side to the right side in FIGS. 5 and 6), and is temporarily leveled from the gradually rising portion. It is a portion sandwiched between the annular member lower part 6b and the cylindrical member 8 until it is bent downward and becomes vertical (from the left side to the right side in FIGS. 5 and 6).
The annular member lower part 6b is smoothly and integrally connected to the cylindrical member 8 through the Coanda surface forming body 9 so as not to disturb the flow of the primary air 21.

  As shown in FIGS. 5 and 6, the injection slit 7 is formed with the inner diameter side annular member upper portion 6a located on the inner diameter side of the annular member upper portion 6a as the injection slit 7a and the Coanda surface forming body 9 as the injection slit 7b. ing. As shown in FIG. 3, the injection slit 7 is provided on the inner peripheral side of the annular member 6 so that the primary air 21 is injected toward the center of the annular member 6.

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.
As described below, the present invention is characterized by the shape of the ejection slit 7, that is, the variation mode of the width of the ejection slit 7 (the variation mode of the width from the left side to the right side in FIGS. 5 and 6). Accordingly, the width of the ejection slit 7 varies depending on the position in the lateral direction (ejection direction) of the ejection slit 7, but the “average width of the ejection slit” has a function of generating the primary air 21 having a high flow velocity as the ejection slit 7. The average value of the range part which has and functions as the injection slit 7 is said.

  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 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.
As described below, the Coanda injector 2 of the present invention is designed to adjust the shape of the injection slit 7 and the bending state of the surface of the Coanda surface forming body 9 so that the Coanda effect can be fully utilized. .

That is, the Coanda injector 2 of the present invention is characterized in that the shape of the jet slit 7 jets the primary air 21 downward from the horizontal plane.
In the conventional Coanda injector for bag filter cleaning, the shape of the injection slit 7 is configured to inject the primary air 21 in a substantially horizontal plane direction.
This is because the shape of the injection slit 7 is considered to be unnecessary because the Coanda effect is used for injecting the primary air 21 below the horizontal plane.

Normally, even if the primary air 21 is jetted in a substantially horizontal plane direction, the jetted primary air 21 bends downward along the Coanda surface of the Coanda surface forming body 9 and flows from above. 22 could be fully accompanied.
Actually, even if the shape of the injection slit 7 does not face downward and is directed in a direction in which the primary air 21 is injected in a substantially horizontal plane direction, a certain amount of Coanda effect is produced, and much of the primary air 21 is It descends along the Coanda surface and can be accompanied by the attraction air 22 from above (for example, Patent Documents 10 to 13).

  However, if the shape of the injection slit 7 is made to be jetted downward from the horizontal plane by the inventor's investigation, the shape of the jet slit 7 is jetted in a substantially horizontal plane direction. Compared to the above, even if the pressure of the primary air 21 and the amount of temporary air per unit time are constant, the wind speed and amount of the amplified air 23 are specifically 1.2 times to 2.1 times, for example. Was also found to increase.

  In the case of the Coanda injector 2 for cleaning the bag filter, since a large amount of primary air 21 is instantaneously injected at a high pressure, a general blower that uses a normal Coanda effect, a continuously operated (continuously jetted) toner Unlike mother particle classifiers, it is easily affected by the direction of the injection slit.

In FIGS. 3, 5, and 6 (1), the shape of the ejection slit 7 is ejected in a substantially horizontal plane direction.
On the other hand, in FIGS. 6 (2) to (4), the shape of the ejection slit 7 is such that the primary air 21 is ejected downward from the horizontal plane.

  In the Coanda injector for bag filter cleaning according to the present invention, the shape of the injection slit 7 is such that the primary air 21 is adjusted by adjusting the relative position between the inner diameter side annular member upper portion 6a and the uppermost point 9p of the Coanda surface forming body. Is preferably sprayed downward from the horizontal plane.

  6 (1) to 6 (4), the position of the uppermost point 9p of the Coanda surface forming body is depicted as being fixed. And the inner diameter side annular member upper part 6a is moving from the left to the right from (1) to (4). In FIG. 6, the relative position between the inner diameter side annular member upper portion 6a and the uppermost point 9p of the Coanda surface forming body is adjusted from (1) to (4). It is made to inject below.

Although described in the embodiment, the Coanda injector 2 having the shape of the injection slit 7 shown in FIG. 6 (4) is compared with the Coanda injector having the shape of the conventional injection slit 7 shown in FIG. 6 (1). The amount of the amplified air 23 has increased to about 1.5 times or more.
Since the amount of primary air 21 injected from the injection slit 7 per unit time should be constant in FIGS. 6 (1) to (4), the primary air 21 is changed from (1) to (4). It is considered that the amount of the attracting air 22 has increased.

In the Coanda injector for bag filter cleaning according to the present invention, the “lowermost or rising point of the upper part of the inner diameter side annular member” 6ap is located closer to the center of the annular member than the uppermost point 9p of the Coanda surface forming body. It is preferable.
“The lowest point or rising point of the upper part of the inner diameter side annular member” 6 ap (in this specification, this point may be simply abbreviated as “the lowest point 6 ap of the upper part of the inner diameter side annular member”) 6, the inner diameter side annular member upper portion 6a rises on the annular member 6 side (to the left side in FIG. 6), and conversely (toward the right side in FIG. 6) does not rise. Say that the uplift will disappear. In FIG. 6, the negative slope approaches 0 from the left to the right, but the lowest point 6 ap at the upper part of the inner diameter side annular member refers to the point at which the slope becomes 0 for the first time.

When the lateral distance between the “lowermost point 6ap on the inner diameter side annular member upper portion” and the “uppermost point 9p of the Coanda surface forming body” is defined as “relative position value d”, d = 0 mm in FIG. 6 (2), d = 0.5 mm, FIG. 6 (3), d = 1 mm, and FIG. 6 (4), d = 2 mm.
Although described in the embodiment, as described above, in the Coanda injector 2 having the shape of the injection slit 7 shown in FIG. 6 (4), the Coanda having the shape of the conventional injection slit 7 shown in FIG. 6 (1). Surprisingly, the amount of the amplified air 23 increased more than about 1.5 times compared to the injector.

The specific value of the relative position value d is not particularly limited depending on the inner diameter of the annular member upper portion 6a, but is preferably 1 mm to 10 mm, more preferably 1.5 mm to 6 mm, and particularly preferably 2 mm to 4 mm. .
If the relative position value d is too small, the primary air 21 is jetted in the horizontal plane direction, so that the amount of air descending along the Coanda surface is reduced, and the Coanda effect cannot be fully exhibited, that is, it is difficult to draw the attraction air 22. Become. The primary air 21 injected in the horizontal direction is wasted without attracting the attraction air 22, resulting in a decrease in the amount of the amplified air 23, and a sufficient amount of air cannot be sent to the bag filter 12. There may be cases where sweeping is not sufficient.
On the other hand, if the relative position value d is too large, the average width of the injection slit 7 becomes large, the wind speed of the primary air 21 cannot be secured, the amount of the attraction air 22 decreases, and the sufficient amplified air 23 is not sent out. There are cases where 12 powders cannot be swept down sufficiently.

  Moreover, in the Coanda injector for bag filter cleaning according to the present invention, as shown in FIG. 7, the Coanda surface on which the injection slit 7b is formed inside the inner diameter side annular member upper portion 6a that forms the injection slit 7a. It is also preferable to provide a primary air guide ring 31 bent downward along the curved surface of the formed body 9. That is, the Coanda injector 2 in which the primary air 21 is jetted below the horizontal plane by providing the primary air guide ring 31 and setting the shape of the jet slit 7 is also preferable as a form of the present invention.

The primary air guide ring 31 is bent downward along the curved surface of the Coanda surface forming body 9 and is installed on the inner diameter side of the annular member upper portion 6a. Normally, the collar is outward, but the shape is such that the collar is inward.
The primary air guide ring 31 is bent downward so that the primary air 21 is jetted downward from the horizontal plane, but the primary air guide ring 31 is bent so that the distance from the curved surface of the Coanda surface forming body 9 is equal. 21 is preferable in order to inject well.

  The width of the primary air guide ring 31 is not particularly limited, but is usually 1 mm to 10 mm, preferably 1.3 mm to 8 mm, more preferably 1.6 mm to 7 mm, and particularly preferably 2 mm to 5 mm.

As a manufacturing method of the Coanda injector for bag filter cleaning of the present invention, the relative position of the “bottom point or rising point of the upper part of the inner diameter side annular member” 6ap with respect to the top point 9p of the Coanda surface forming body is changed, Alternatively, a primary air guide ring bent downward is provided inside the upper part of the inner diameter side annular member, and the amount of the amplified air 23 sent to the bag filter 12 per unit time is the amount of the primary air 21 injected per unit time. A manufacturing method in which the shape of the injection slit 7 is set so as to be twice or more of is preferable.
The shape of the ejection slit 7 is set so that it is more preferably 2.7 times or more, particularly preferably 3.4 times or more.

As shown in FIGS. 6 (1) to 6 (4), the lowest point 6ap at the upper part of the inner diameter side annular member is moved with respect to the highest point 9p of the Coanda surface forming body, and the amount of the amplified air 23 is increased per unit time. The Coanda injector 2 is manufactured by searching for a point that is twice or more the amount of the primary air 21 to be injected.
Alternatively, the Coanda injector 2 is manufactured by adjusting the width of the primary air guide ring and searching for a point where the amount of the amplified air 23 is twice or more the amount of the primary air 21 injected per unit time.
Particularly preferably, the Coanda injector 2 is manufactured by searching for a point where the amount of the amplified air 23 is maximized.

More specifically, the “lowermost point 6 ap on the inner diameter side annular member upper part” is gradually moved from the “uppermost point 9 p of the Coanda surface forming body” to the center side (inner side) of the annular member 6, and the amplified air 23 The Coanda injector 2 is manufactured by searching for the point where the amount of the maximum value is maximized.
The method of gradually moving may change the position where the annular member upper part 6a and the annular member lower part 6b are caulked, but based on different design drawings, a plurality of parts having different relative position values d may be manufactured again. Good.

  The bag filter main body 11 is configured by installing one Coanda injector 2 for cleaning the bag filter according to the present invention above the plurality of aligned bag filters 12 one by one. In FIG. 1 and FIG. 2, only one column is drawn. Usually, the bag filter body 11 is configured by arranging several to several hundreds vertically and horizontally.

In the operation of the bag filter body 11, the powder of the bag filter 12 is periodically swept off. However, if the Coanda injector 2 of the present invention is used, it adheres and accumulates on the outer surface of the bag filter 12 at the time of one powder sweep. Therefore, the frequency of the powder sweeping can be reduced by temporarily interrupting the regular filtration operation.
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 comprising 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.
As shown in FIGS. 6 (1) to 6 (4), the “relative position value” is a lateral distance between the “lowermost point 6ap on the inner diameter side annular member upper part” and the “uppermost point 9p of the Coanda surface forming body”. In FIG. 6 (1), d = 0 mm, d = 0.5 mm in FIG. 6 (2), d = 1mm in FIG. 6 (3), and d = 2mm in FIG. 6 (4).

103 L of compressed air was supplied from the connection hole into the annular member per ^{second at} a pressure of 3 kgf / cm ² from the compressed air tube.
By changing the relative position value d, the wind speed of the amplified air sent downward from the cylindrical member of the Coanda injector was measured.
The results are listed in Table 1.

As can be seen from Table 1, no. From (1) to No. Toward (4), the shape of the injection slit is such that the primary air is injected from below the horizontal plane, but the wind speed of the amplified air (that is, the amount of amplified air) increases accordingly. I understood that.
No. For the Coanda injector (1), no. In the Coanda injector (4), the powder scavenging efficiency of the bag filter located therebelow was about 1.5 times.

Example 2
A Coanda injector comprising the annular member and the cylindrical member shown in FIGS. However, in the annular member, a primary air guide ring as shown in FIG. 7 is provided inside the upper part of the inner diameter side annular member forming the upper part of the injection slit.
The length (overhang width) of the primary air guide ring was 5 mm. The installed primary air guide ring was set so that the distance (slit width) between the Coanda surface forming body and the Coanda surface was constant.
The obtained Coanda injector is designated No. (5).

No. (5) was evaluated in the same manner as in Example 1, and the measured value of the air volume of the amplified air was 25.0 [m / sec]. The relative value to (1) was (25.0 / 13.3 =) 1.88 times.
Further, the amplification factor with respect to the primary air, that is, [amplified air amount / primary air amount] was 3.44.
That is, no. For the Coanda injector (1), no. In the Coanda injector of (5), the powder sweeping efficiency of the bag filter located underneath it markedly increased.

  The Coanda injector of the present invention sends a large amount of amplified air to the bag filter when the bag filter is swept away, and can be widely used in the field of removing powder from gas. It is also used when a new bag filter body is introduced and when an existing injector part is replaced.

2 Coanda injector for bag filter cleaning 3 Connection hole 4 Compressed air pipe 5 Auxiliary member 6 Annular member 6a Annular member upper part 6ap The lowest point of the inner diameter side annular member upper part 6b Annular member lower part 7 Injecting slit 7a Injecting slit upper part 7b Injecting slit lower part 8 Tubular member 9 Coanda surface forming body 9p Topmost point of Coanda surface forming body 11 Bag filter body 12 Bag filter 13 Perforated plate 21 Primary air 22 Attracting air 23 Amplified air 31 Primary air guide ring d Relative position value X Compressed air

Claims (17)

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 to 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 in a pulse form through the connection hole; A cylindrical member that is located on the lower coaxial line and that sends amplified air accompanied by air attracted from above to the primary air when the primary air is instantaneously jetted from the jet slit in a pulsed manner. Coanda injector for cleaning bug filters
The annular member includes an annular member lower part and an annular member upper part, and the annular member lower part and the tubular member are integrated via a Coanda surface forming body,
The shape of the injection slit formed with the upper part of the inner diameter side annular member positioned on the inner diameter side of the upper part of the annular member as the upper part of the injection slit and the Coanda surface forming body as the lower part of the injection slit causes the primary air to be injected downward from the horizontal plane. Coanda injector for bag filter cleaning, characterized in that   The Coanda injector for bag filter cleaning according to claim 1, wherein the connection hole is present in a lower portion of the annular member.   The Coanda injector for bag filter cleaning according to claim 1, wherein only one connection hole is present in the annular member.   The Coanda injector for bag filter cleaning according to any one of claims 1 to 3, wherein the annular member lower part and the annular member upper part are connected by caulking the outer peripheral side.   The shape of the injection slit is such that the primary air is injected below the horizontal plane by adjusting the relative position between the upper part of the inner diameter side annular member and the uppermost point of the Coanda surface forming body. The Coanda injector for bag filter cleaning according to claim 4.   The Coanda injector for bag filter cleaning according to claim 5, wherein a lowermost point or a rising point of the upper part of the inner diameter side annular member is located closer to a center side of the annular member than an uppermost point of the Coanda surface forming body.   The primary air guide ring bent downward along the curved surface of the Coanda surface forming body forming the lower portion of the jet slit is provided inside the upper portion of the inner diameter side annular member forming the upper portion of the jet slit. The Coanda injector for bag filter cleaning according to any one of claims 4 to 4.   The Coanda injector for bag filter cleaning according to claim 7, further comprising a primary air guide ring bent downward so that the distance from the curved surface of the Coanda surface forming body is equal.   The Coanda injector for bag filter cleaning according to any one of claims 1 to 8, wherein each one is installed on top of a plurality of aligned bag filters. Bug filter body.   The bag filter body according to claim 9, wherein only one compressed air pipe is provided laterally at a portion which is a side surface of the cylindrical member and is below one side of the annular member.   The bag filter body according to claim 10, wherein only one auxiliary member into which compressed air does not flow is provided under the other side of the annular member. The coanda injector for bag filter cleaning according to any one of claims 1 to 6, wherein the amplified air is instantaneously sent from above to the bag filter when the powder is swept away from the bag filter. A manufacturing method comprising:
An annular member having a connection hole to which compressed air is supplied from a compressed air pipe, and an injection slit for injecting compressed air supplied in a pulse form through the connection hole on the circumference of the inner diameter of the Coanda injector; When the primary air is instantaneously ejected in a pulse form from the ejection slit, which is located on the lower coaxial side of the annular member, the amplified air accompanied by the induced air from above is sent out to the bag filter. Formed from a cylindrical member,
The annular member is formed from an annular member lower part and an annular member upper part, and the annular member lower part and the cylindrical member are integrated via a Coanda surface forming body,
The upper part of the annular member located on the inner diameter side of the upper part of the annular member is the upper part of the injection slit, and the shape of the injection slit is formed by using the Coanda surface forming body as the lower part of the injection slit. And
A coanda injector for bag filter cleaning, characterized in that the primary air is jetted below a horizontal plane by adjusting the relative position between the upper part of the inner diameter side annular member and the uppermost point of the Coanda surface forming body. Method.   The amount of amplified air sent to the bag filter per unit time is injected per unit time by changing the relative position of the lowest point or rising point of the upper part of the inner diameter side annular member with respect to the uppermost point of the Coanda surface forming body. The manufacturing method of the Coanda injector for bag filter cleaning of Claim 12 which sets the shape of an injection slit so that it may become 2 times or more of the quantity of primary air to be performed.   The manufacturing method of the Coanda injector for bag filter cleaning of Claim 12 or Claim 13 which sets the shape of an injection slit by searching the point where the quantity of amplified air becomes the maximum.   The point at which the amount of amplified air is maximized is searched for by gradually moving the lowest point of the upper part of the inner diameter side annular member from the uppermost point of the Coanda surface forming body to the center side of the annular member. The manufacturing method of the Coanda injector for bug filter cleaning as described.   The method for manufacturing a Coanda injector for bag filter cleaning according to claim 14 or 15, wherein a point where the amount of the amplified air is maximized is searched by changing a position where the annular member lower part and the annular member upper part are caulked.   A manufacturing method for manufacturing the Coanda injector for bag filter cleaning according to claim 7 or claim 8, wherein a primary air guide ring bent downward is provided inside the upper part of the inner diameter side annular member, and a unit. A method of manufacturing a Coanda injector for cleaning a bag filter, wherein the shape of the injection slit is set so that the amount of amplified air sent to the bag filter in time is more than twice the amount of primary air injected in unit time.

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