JP7242440B2 - Suction nozzle, pneumatic unloader and particle suction method - Google Patents

Description

The present invention relates to suction nozzles and pneumatic unloaders.

Conventionally, in the aquaculture of marine products such as fish and shellfish, a system has been used in which feed is stored in storage tanks installed on the sea, and the feed supplied from the storage tank is fed to fish and shellfish stored in fish cages ( For example, see Patent Document 1). In such aquaculture systems, pneumatic unloaders are used to supply feed from bulk ships loaded with feed to storage tanks at sea.

In recent years, wood pellets and densified semi-carbonized wood pellets, which have come to be treated in the same way as fossil fuels in energy trading, have been imported from overseas as well as domestic consumption has increased. . Currently, container transportation is the main transportation, but the transportation of bulk ships is also increasing, and it is expected that the use of pneumatic unloaders will increase.

Generally, a pneumatic unloader is used to unload cargo (wheat, etc.) from a ship, and is equipped with a vacuum blower, a transfer pipe connected to the vacuum blower, and a suction nozzle connected to the tip of the transfer pipe. ing. At the time of unloading, the suction nozzle is inserted into the cargo on the ship from above, and the cargo is sucked up by the suction force of the vacuum blower. The cargo sucked into the suction nozzle is pneumatically conveyed through the conveying pipe and stored in a land tank or the like. This type of pneumatic unloader may have a limited lifting height compared to other grab bucket or mechanical unloaders, but there is no big difference in the required power, and the structure as a cargo handling machine is simple. It also has the advantage of requiring no special modification on the bulk carrier side.

A suction nozzle used in a pneumatic unloader as described above has an outer cylinder and an inner cylinder that constitute a double pipe structure. It is improved by a secondary air flow generated during (see, for example, Patent Document 2).
Further, such a suction nozzle conventionally employs a "bell mouth/throttle structure" in which the inner tube forms a bell mouth shape and the outer tube forms a throttle shape, forming a three-dimensional curved surface. This is because the "bell mouth/squeeze structure suction nozzle" has a higher suction efficiency than the "straight tube/straight tube structure" suction nozzle whose inner and outer tubes are straight. can be sucked (see, for example, Non-Patent Document 1).

JP 2018-11572 A JP 2013-159468 A

Takeshi Kano, "Study on Performance Improvement of Powder Suction Nozzle", Kagaku Kogaku Ronbunshu, Vol. 10, No. 2 (1984)

However, the above-mentioned Non-Patent Document 1 demonstrates the suction efficiency of the suction nozzle when sucking powder particles with a diameter of about 1 mm, but granules such as aquaculture feed and wood pellets are non-patent document 1 have a larger diameter than the granules disclosed in. That is, conventionally, sufficient examination has not been made on the suction efficiency of the suction nozzle when sucking grains such as aquaculture feed and wood pellets.
In addition, the bell mouth/squeeze structure suction nozzle that is conventionally used forms a complicated three-dimensional curved surface, so that it is difficult to manufacture and repair it.

SUMMARY OF THE INVENTION An object of the present invention is to provide a suction nozzle and a pneumatic unloader that can simplify the structure without lowering the suction efficiency for granules with a minimum dimension of 2 mm or more.

The present invention is a suction nozzle for sucking granules having a minimum dimension of 2 mm or more, comprising: an inner cylinder formed inside with a granule flow path for circulating the granules; and the inner cylinder surrounding the inner cylinder. an outer cylinder arranged coaxially with the outer cylinder and formed with an air flow path for circulating air between the inner cylinder and the outer peripheral surface of the inner cylinder, wherein the inner cylinder and the outer cylinder each have a constant inner diameter, The tip of the inner cylinder that forms the inlet of the granule flow path is arranged so as to protrude from the tip of the outer cylinder that forms the outlet of the air flow path. The distance in the axial direction from the tip of the outer cylinder to the tip of the inner cylinder is set to be greater than 0 and equal to or less than 1.00D.
In the present invention, the minimum dimension is the minimum dimension in the outer shape of the granule, and refers to the dimension showing the minimum value among the diameter, length, width, etc. of the pellet.

The suction nozzle of the present invention forms a simple three-dimensional shape as compared to conventional suction nozzles constructed with a bellmouth/restriction structure because the inner diameters of the inner and outer cylinders are constant.
Further, the suction nozzle of the present invention sucks granules by driving an external negative pressure source connected to the inner cylinder with the tip of the inner cylinder and the tip of the outer cylinder inserted into the granule layer. do. At this time, an air flow that sucks the granules in the granule layer is generated in the granule channel of the inner pipe, and the inlet of the granule channel (granule A secondary air flow occurs due to the suction force generated near the air inlet.
Here, the tip of the inner cylinder that forms the granule inlet is arranged to protrude by an appropriate distance from the tip of the outer cylinder that forms the outlet of the air flow path (air outlet). Therefore, the secondary air flow flowing out from the air outlet can permeate a wide range of the granule layer and fluidize the granule layer over a wide range.
In addition, since the secondary air flow permeates a wide range of the granule layer, the force (pushing force) of the secondary air flow pushing each granule toward the central axis of the suction nozzle is reduced, and the granule flow path The diameter of the flux of granules flowing through the can be increased. As a result, it is possible to increase the suction efficiency of the granules. In addition, granules with a minimum dimension of 2 mm or more are less likely to ride in the flow of the secondary air flow than granules with a minimum dimension of 1 mm or less, which are targeted by conventional suction nozzles. is larger than before.
As a result, the suction nozzle of the present invention can suck granules with a minimum size of 2 mm or more with suction efficiency as high as or higher than that of a conventional suction nozzle.
Therefore, according to the present invention, there is provided a suction nozzle whose structure can be simplified without lowering the suction efficiency even when granules with a minimum dimension of 2 mm or more are sucked, and the suction nozzle can be manufactured and repaired easily.

In the suction nozzle of the present invention, it is preferable that the ratio of the cross-sectional area of the air flow path to the cross-sectional area of the particle flow path is set within the range of 0.17 or more and 0.50 or less.
According to such a configuration, it is possible to improve the suction efficiency of the granules.
In the present invention, the cross-sectional area of the granule channel and the cross-sectional area of the air channel refer to cross-sectional areas perpendicular to the direction in which the granules and air flow in each channel.

In the suction nozzle of the present invention, it is preferable that the distance from the tip of the outer cylinder to the tip of the inner cylinder is set within a range of 0.17D or more and 0.83D or less.
In such a suction nozzle of the present invention, the ratio of the cross-sectional area of the air flow path to the cross-sectional area of the particle flow path is set in the range of 0.20 or more and 0.40 or less. preferable.
According to such a configuration, it is possible to further improve the suction efficiency of the granules.

In the suction nozzle of the present invention, it is preferable that the distance from the tip of the outer cylinder to the tip of the inner cylinder is set within a range of 0.17D or more and 0.67D or less.
In such a suction nozzle of the present invention, the ratio of the cross-sectional area of the air flow path to the cross-sectional area of the particle flow path is set in the range of 0.25 or more and 0.33 or less. preferable.
According to such a configuration, the suction efficiency of the particles can be most improved.

A pneumatic unloader of the present invention is characterized by comprising the suction nozzle described above. As a result, the same effects as those of the suction nozzle of the present invention described above can be obtained.

ADVANTAGE OF THE INVENTION According to this invention, the suction nozzle and pneumatic unloader which can simplify a structure can be provided, without reducing suction efficiency with respect to the particle of minimum dimension 2 mm or more.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram which shows a part of culture system of one Embodiment of this invention. Sectional drawing which shows the suction nozzle of the said embodiment. 5 is a graph showing the relationship between the amount of deviation of the tip of the double tube and the solid-gas ratio; 4 is a graph showing the relationship between the double tube cross-sectional area ratio and the solid-gas ratio; Graph showing the relationship between pellet diameter and solid-gas ratio. The schematic diagram which shows a motion of the pellet sucked by the suction nozzle. The schematic diagram which shows a motion of the pellet sucked by the suction nozzle. The schematic diagram which shows a motion of the pellet sucked by the suction nozzle. Sectional drawing which shows the conventional suction nozzle.

An embodiment of the present invention will be described below with reference to the drawings.
[Aquaculture system 100]
In FIG. 1, an aquaculture system 100 includes a plurality of cages (not shown), a feeding device 10 that supplies feed to these cages, a pneumatic unloader 20 that supplies feed to the feeding device 10, and a and a structure 40 .

The feeding apparatus 10 has a storage tank 11 in which granular feed is stored, a transport pipe 12 extending from the storage tank 11 to a fish tank, and an airflow generator 13 that forms a transport airflow inside the transport pipe 12 .
The storage tank 11 is installed in a portion of the structure 40 above the sea surface. Further, the storage tank 11 is configured by a so-called hopper or the like, and can store granular feed inside and can supply a predetermined amount of feed at a time from a supply section 110 at the bottom. One end of the transport pipe 12 is connected to the supply section 110 of the storage tank 11, and the other end (not shown) is introduced into the fish tank. The airflow generator 13 is composed of an electric motor or an engine-driven air compressor or the like. can be transported.

It should be noted that the feed in the present embodiment is granular with a minimum dimension of 2 mm or more. The shape of the granules is not particularly limited, but is, for example, a pellet shape (see pellet pt in FIG. 6). When the feed is pellet-shaped granules, each of the diameter dp and the length lp of the pellet pt should be 2 mm or more (see FIGS. 6 to 8). On the other hand, when the feed is granules of other shapes, the minimum dimension of the shape should be 2 mm or more.

The pneumatic unloader 20 includes a separator 21 installed in a portion of the structure 40 above the sea surface, a vacuum blower 22 as a negative pressure source connected to the separator 21, and a carrier connected to the separator 21. A pipe 23 and a suction nozzle 30 connected to the tip of the transport pipe 23 and inserted into feed loaded on the ship 5 are provided.
The feed loaded on the ship 5 is sucked into the suction nozzle 30 together with air, and then introduced into the separator 21 via the carrier pipe 23 . The feed separated from the air by the separator 21 is supplied to the storage tank 11 , while the air separated from the feed is sucked into the vacuum blower 22 .

The structure 40 is composed of a steel-framed turret or the like, and is installed in the vicinity of the fixed fish tank. As shown in FIG. 1, the structure 40 may have a lower part fixed to the seabed and an upper part placed on the sea surface, or may have a structure using a floating body such as a ship or a barge.

[Suction nozzle]
A detailed structure of the suction nozzle 30 according to this embodiment will be described.
As shown in FIG. 2, the suction nozzle 30 has a so-called double-tube structure. and an outer cylinder 32 in which a flow path 320 is formed.

The inner cylinder 31 of the present embodiment is a straight tubular cylinder with a constant inner diameter. The inner cylinder 31 has an inner cylinder base end portion (not shown) connected to the conveying pipe 23 and an inner cylinder front end portion 312 forming the particle inlet 31 a of the particle flow path 310 .

The outer cylinder 32 of this embodiment is a straight tubular cylinder having a larger diameter than the inner cylinder 31 and a shorter length than the inner cylinder 31, and has a constant inner diameter. That is, the suction nozzle 30 of the present embodiment has a straight pipe/straight pipe structure in which the inner cylinder 31 and the outer cylinder 32 are straight pipes.
Further, the outer cylinder 32 is arranged in a state surrounding the inner cylinder 31 and attached to the inner cylinder 31 via an arbitrary fastener. The outer cylinder 32 has an outer cylinder base end portion 321 forming an air inlet 32a of the air flow path 320, and an outer cylinder distal end portion forming an air outlet 32b of the air flow path 320 near the particle inlet 31a. 322.
The central axis of the inner cylinder 31 and the central axis of the outer cylinder 32 coincide with each other and are shown as axis C in the drawing.

Here, the suction nozzle 30 of the present embodiment is configured as follows so as to suitably suck feed that is grains with a minimum size of 2 mm or more.
That is, in the present embodiment, the inner cylinder front end portion 312 is arranged to project from the outer cylinder front end portion 322 in the direction of the axis C, and is exposed from the outer cylinder 32 . Specifically, when the inner diameter of the inner cylinder 31 is D, the distance in the direction of the axis C from the distal end portion 322 of the outer cylinder to the distal end portion 312 of the inner cylinder (double-tube tip deviation amount s) is greater than 0, And it is set to 1.00D or less.
In this embodiment, the ratio A2/A1 (double tube cross-sectional area ratio α) of the cross-sectional area A2 of the air flow path 320 to the cross-sectional area A1 of the particle flow path 310 is 0.17 or more and 0.50 or less. It is preferably set to a range.

Further, it is more preferable that the amount of deviation s at the tip of the double tube is set in the range of 0.17D or more and 0.83D or less, and in this case, the double tube cross-sectional area ratio α is 0.20 or more and 0 It is preferably set in the range of 0.40 or less.
Furthermore, it is more preferable to set the amount of deviation s at the tip of the double tube to a range of 0.17D or more and 0.67D or less. It is preferably set in the range of 0.33.

The operation of the suction nozzle 30 of this embodiment described above will be described with reference to FIG. 8 exemplified later.
First, the suction nozzle 30 is inserted into the feed (grain layer P) from above in the vertical direction, and the inner cylinder front end 312 and the outer cylinder front end 322 are arranged in the grain layer P. As shown in FIG. In this state, when the vacuum blower 22 is driven, an ascending air current that sucks air and particles from the particle layer P is generated in the particle flow path 310 of the inner cylinder 31 . In addition, a secondary air flow is generated in the air flow path 320 between the inner cylinder 31 and the outer cylinder 32 due to the suction force generated in the vicinity of the particle inlet 31 a of the particle flow path 310 . This secondary airflow flows into the air flow path 320 from the air inlet 32a, permeates the granule layer P from the air outlet 32b, and then flows into the granule inlet 31a. The granule layer P in the range penetrated by the secondary airflow is fluidized, and each granule moves toward the granule inlet 31a together with the secondary airflow.

[Effects of Embodiment]
According to this embodiment, the following effects are obtained.
Since the suction nozzle 30 of the present embodiment has a constant inner diameter of each of the inner cylinder 31 and the outer cylinder 32 and has a straight tube/straight tube structure, it is similar to a conventional suction nozzle having a bellmouth/throttle structure. forms a simple three-dimensional shape compared to .
In addition, in the suction nozzle 30 of the present embodiment, the tip end portion 312 of the inner cylinder forming the particle inlet 31a is arranged in a state of protruding by an appropriate distance from the tip end portion 322 of the outer cylinder forming the air outlet 32b. there is Therefore, the secondary air flow that has flowed out from the air outlet 32b can permeate a wide range of the granule layer P and fluidize the granule layer P over a wide range.
In addition, since the secondary air flow permeates the granule layer P in a wide range, the force (pushing force) of the secondary air flow that pushes each granule toward the axis C is reduced, and the granule flow path 310 is reduced. The diameter of the flux of flowing particles (for example, the pellet flow radius rf in FIG. 8) increases. As a result, it is possible to increase the suction efficiency of the granules. In addition, granules with a minimum dimension of 2 mm or more are less likely to ride in the flow of the secondary air flow than granules with a minimum dimension of 1 mm or less, which are targeted by conventional suction nozzles. is larger than before.
Therefore, the suction nozzle 30 of the present embodiment can suck granules with a minimum size of 2 mm or more with suction efficiency as high as or higher than that of a conventional suction nozzle.
Therefore, according to the present embodiment, there is provided a suction nozzle 30 that does not lower the suction efficiency when sucking particles with a minimum dimension of 2 mm or more and has a simplified structure, and manufacture and repair of the suction nozzle 30. becomes easier.

Further, in the suction nozzle 30 of the present embodiment, the suction efficiency can be further improved by setting the double-pipe tip deviation amount s and the double-pipe cross-sectional area ratio α within the ranges described above.
In addition, the efficiency of sucking particles will be described in detail with reference to Examples described later.

Next, examples of the present invention and comparative examples will be described. Note that, for the components corresponding to the above-described embodiments, the same reference numerals as those of the above-described embodiments are used for convenience even under conditions outside the scope of the present invention.

A suction tester that simulates the pneumatic unloader 20 described in the above embodiment was created, and a test of sucking pellets (granules) as feed was conducted using this suction tester. In this test, the test time was set to 1 minute or longer, the amount of air and the amount of pellets sucked into the suction nozzle 30 were measured, and the solid-gas ratio (amount of pellets (t)/amount of air (t)) was calculated. .

The lift from the suction nozzle 30 to the separator 21 was about 14 m, and the speed of the transported pellets was about 10 m/sec.
Also, as the vacuum blower 22 used in the suction tester, a blower with air volume-static pressure characteristics of a static pressure of −95 kPa and a maximum air volume of 20 Nm 3 /min was used. When the air volume was insufficient, two of the same blowers were connected in parallel and operated.
The pellets used this time have a true specific gravity ranging from 1.15 to 1.40, with an average value of 1.30. The bulk density of the pellets before tapping ranged from 0.61 to 0.72 with an average value of 0.66. The bulk density of the tapped pellets ranged from 0.66 to 0.74, with an average value of 0.70.
In addition, the inner diameter of the inner cylinder of the double-pipe nozzle was set to φ155 with a guideline of 10 times the pellet diameter so that pellets with a maximum diameter of φ16 can be stably sucked.

(Double tube tip deviation amount s)
First, in a suction tester, changes in the solid-gas ratio were investigated when the deviation amount s of the tip portion of the double tube of the suction nozzle 30 was changed while the inner diameter D of the inner cylinder 31 was fixed. The results are shown in Table 1. The diameter dp (minimum dimension) of the pellets used was 8 mm.
In Table 1, Examples 1 to 3 are straight tube/straight tube structure suction nozzles 30, and the values of the double tube cross-sectional area ratio α are different from each other.
On the other hand, Comparative Examples 1 to 3, as shown in FIG. 9, are suction nozzles 50 having a bellmouth/throttle structure, and have different values of the double tube cross-sectional area ratio α. The suction nozzle 50 has a bell-mouth inner cylinder 51 and an aperture-shaped outer cylinder 52 .

In each of the following examples, the deviation amount s of the tip of the double tube in the state where the inner cylinder 31 protrudes from the outer cylinder 32 is set to a positive value, and in the configuration in which the outer cylinder 32 protrudes from the inner cylinder 31 A double tube front end shift rate s/D, which is a ratio of the double tube front end shift amount s to the inner diameter D of the inner cylinder 31, was calculated using the double tube front end shift amount s as a negative value. The same applies to each comparative example.
Further, among Examples 1 to 3, cases in which the double tube tip deviation ratio s/D is in the range of 0.00 to 1.00 are included in the scope of the present invention.
Further, in Comparative Examples 1 to 3, when s/D=0 (s=0), the curved surfaces of the inner cylinder 51 and the outer cylinder 52 interfere with each other, so no test was performed.

3 is a graph showing the test results (Examples 1 to 3) shown in Table 1. FIG.
As shown in FIG. 3, even in Example 1, which tends to have a low solid-gas ratio among Examples 1 to 3, the tip deviation rate s/D of the double tube is in the range of 0.00 to 1.00. , a solid-gas ratio of at least around 10 was obtained.
Specifically, in Example 1, while the tip deviation rate s/D of the double tube increased from -0.5 to 0 in increments of 0.17, the solid-gas ratio was almost doubled or more. is increasing sharply in Moreover, while the double tube tip shift rate s/D increased from 0 to 1.0, the solid-gas ratio reached a peak when the double tube tip shift rate s/D was 0.50. It changes like drawing a mountain, and when the double pipe tip deviation ratio s/D becomes larger than 1.0, the solid-gas ratio decreases greatly.
Although the data in Table 1 are omitted, the above-mentioned tendency in Example 1 is the same in Examples 2 and 3, and the solid-gas ratio is 0 when the tip deviation rate s/D of the double tube is 0. In the range of 0.00 to 1.00, it varied at a higher level than in the other ranges.
Further, as shown in FIG. 3, according to Examples 1 to 3, it is preferable that the tip deviation ratio s/D of the double tube is in the range of 0.17 to 0.83, more preferably 0.17 to 0.83. It has been found to be more preferred if it is in the range of 67, with 0.5 being most preferred.

On the other hand, in Comparative Examples 1 to 3, if the conditions for the cross-sectional area ratio α of the double tube were the same as in Examples 1 to 3, the double tube tip deviation rate s/D was tested in all ranges. , the solid-gas ratio was smaller than in Examples 1 to 3 (see Table 1).
In particular, in Comparative Example 1, in which the solid-gas ratio tends to be low among Comparative Examples 1 to 3, in order to obtain a solid-gas ratio of at least around 10, the tip deviation rate s/D of the double pipe is 0.17 to 0.17. It was required to be in the range of 0.83.

Further, the maximum solid-gas ratio obtained from Comparative Examples 1 to 3 was around 20. According to Non-Patent Document 1, the optimum double tube cross-sectional area ratio α in a suction nozzle with a bell mouth/throttle structure is about 1/3 (about 0.33), so Comparative Examples 1 to 3 The maximum solid-gas ratio of around 20 obtained from is considered to be the maximum solid-gas ratio of the bellmouth/restriction structure obtained in this test.
On the other hand, in Examples 2 and 3, when the tip deviation rate s/D of the double tube was in the range of 0.17 to 0.67, the maximum solid-gas ratio obtained in Comparative Examples 1 to 3 ( 20) was obtained.

(Double pipe cross-sectional area ratio α)
Next, in a suction tester, changes in the solid-gas ratio were investigated when the cross-sectional area ratio α of the double tube was changed. Table 2 shows the results. The diameter dp (minimum dimension) of the pellets used was 8 mm.
In Table 2, Examples 4 to 10 are suction nozzles 30 having a straight tube/straight tube structure, and have different values of the double tube tip deviation amount s. Examples 4 to 10 are included in the scope of the present invention.

4 is a graph showing the test results shown in Table 2. FIG.
As shown in FIG. 4, in Examples 4 to 10 in which the amount of deviation s at the tip of the double tube is in the range of 0.00 to 1.00, the cross-sectional area ratio α of the double tube is in the range of 0.17 to 0.50. In the range, a gas-to-solid ratio of at least around 10 was obtained.
Further, in Examples 5 to 9 in which the double tube tip deviation rate s/D is in the range of 0.17 to 0.83, the double tube cross-sectional area ratio α is in the range of 0.20 to 0.40. In this case, a solid-gas ratio of at least around 15 was obtained.
Furthermore, in Examples 5 to 8 in which the double tube tip deviation rate s/D is in the range of 0.17 to 0.67, the double tube cross-sectional area ratio α is in the range of 0.25 to 0.33. In this case, a solid-gas ratio of at least around 20 was obtained.
That is, as described above, the maximum solid-gas ratio obtained in Comparative Examples 1 to 3 is around 20, so in Examples 5 to 8, the double pipe cross-sectional area ratio α is 0.25 to 0.33. Within the range, a solid-gas ratio equal to or higher than the maximum solid-gas ratio obtained in Comparative Examples 1 to 3 was obtained.

(Diameter of pellet)
Next, in Examples 1 to 10 described above, the conditions under which a relatively high solid-gas ratio was obtained (double-tube tip deviation rate s/D: 0.50, double-tube cross-sectional area ratio α: 0.25 ) was used to examine the change in the solid-gas ratio when the diameter of the pellet was changed using the straight tube/straight tube structure suction nozzle 30 (Example). In addition, in Comparative Examples 1 to 3, the conditions under which a relatively high solid-gas ratio was obtained (double-tube tip deviation rate s/D: 0.50, double-tube cross-sectional area ratio α: 0.33) Using the suction nozzle 50 (comparative example) with a bellmouth/squeeze structure, changes in the solid-gas ratio when the pellet diameter was changed were examined in the same manner as described above. These results are shown in FIG.
In addition, the diameter of a pellet is the minimum dimension of the said pellet.

As shown in FIG. 5, the solid-gas ratio when sucking pellets with a diameter of 1 mm was significantly higher in the comparative example than in the example. However, when the diameter of the pellet was 2 mm or more, a higher solid-gas ratio could be obtained in the example than in the comparative example.

From the above results, in the case of sucking pellets with a diameter of 2 mm or more, in the suction nozzle 30 with a straight tube/straight tube structure, the double tube tip deviation rate s / D and the double tube cross-sectional area ratio α It has been clarified that by setting as in the embodiment, a suction efficiency equal to or higher than that of a suction nozzle with a conventional bell mouth/throttle structure can be realized.

(observation and simulation)
Next, in order to examine the influence of the double tube tip deviation amount s on the pellet suction efficiency, a test was conducted to observe the pellets in the suction nozzle 30 . In this test, by dividing the suction nozzle 30 and providing a transparent panel, the inside of the suction nozzle 30 can be visualized, and the pellets pt (Figs. ) was measured around the axis C of the flux (pellet flow radius rf). The diameter dp (minimum dimension) of the pellets used is 8 mm.

6 to 8 show the suction nozzle 30 divided into quarters around the axis C and the particle layer P of the pellets pt packed around the suction nozzle 30. FIG. 6 to 8 exemplify some pellets pt that constitute the particle layer P, but the illustration of most of the pellets is simplified.

In the suction nozzles 30 shown in FIGS. 6 to 8, the double tube cross-sectional area ratio α is set to a common value (0.33), and the double tube tip deviation rate s/D is 0 to 0.33. set to different values in the range.
As shown in FIG. 6, the pellet flow radius rf was about 31% with respect to the inner diameter D of the inner cylinder 31 when the tip deviation ratio s/D of the double tube was 0.
As shown in FIG. 7, when the double tube tip deviation rate s/D is 0.17, the pellet flow radius rf is about 55% of the inner diameter D of the inner cylinder 31, and is shown in FIG. higher than the case.
As shown in FIG. 8, when the double tube tip deviation rate s/D is 0.33, the pellet flow radius rf is about 68% of the inner diameter D of the inner cylinder 31, which is the highest. .
Although not shown, the pellet flow radius rf was about 66% of the inner diameter D of the inner cylinder 31 when the double tube tip deviation rate s/D was 0.50.
As a result of the above observation, the ratio of the pellet flow radius rf to the inner diameter D of the inner cylinder 31 changes due to the change in the double tube tip shift rate s/D, and the change correlates with the solid-gas ratio. found to be related. That is, it was found that the solid-gas ratio increased as the pellet flow radius rf increased.

Here, the results of simulation analysis of the secondary air flow near the suction nozzle 30 and the movement of the pellet pt are indicated by arrows in FIGS. 6 to 8, arrows (thin) indicate the direction of secondary air flow, and arrows (thick) indicate the trajectory of the pellets pt existing near the tip of the suction nozzle 30. FIG.

As shown in FIGS. 6 to 8, the larger the tip deviation ratio s/D of the double pipe, the wider the region R of the secondary air flow that permeates the particle layer P. As shown in FIGS. Specifically, the maximum distance DR from the radial axis C of the suction nozzle 30 to the boundary of the secondary airflow region R is the largest in the case shown in FIG.
When the region R of the secondary air flow penetrating into the granular material layer P is expanded in this way, the horizontal component of the secondary air flow in this region R is reduced, so it is thought that the force pushing the pellet pt in the horizontal direction is reduced. be done. When the force pushing the pellet pt in the horizontal direction becomes smaller, it is considered that the amount of horizontal movement of the pellet pt becomes smaller and the pellet flow radius rf becomes larger.
In addition, since the pellet pt has a minimum dimension of 2 mm or more and has a larger inertial force than particles with a diameter of 1 mm or less, which are targeted by conventional suction nozzles, it is difficult to ride on the secondary air flow. Therefore, in order to increase the pellet flow radius rf when sucking pellets pt with a minimum dimension of 2 mm or more, it is considered that reducing the above-mentioned "force pushing the pellets in the horizontal direction" will be more important than before. be done.
However, if the region R of the secondary air flow becomes larger than a certain value, it is considered that the force for fluidizing the pellets pt is weakened.
According to the above observations and simulations, it was found that by appropriately setting the tip deviation ratio s/D of the double tube, the pellet flow radius rf can be suitably increased, thereby improving the solid-gas ratio. rice field.

(summary)
In the prior art, it was thought that a higher suction efficiency could be obtained with a bellmouth/squeeze structure than with a straight pipe/straight pipe structure as the shape of the suction nozzle. It was found that when the dimension is 2 mm or more, a higher suction efficiency can be obtained with the straight tube/straight tube structure than with the bellmouth/throttle structure.
Further, according to the above-described embodiment, in the suction nozzle 30 having a straight pipe/straight pipe structure, by setting the tip deviation ratio s/D of the double pipe and the cross-sectional area ratio α of the double pipe to suitable ranges, the bell It was found that a suction efficiency equal to or greater than the maximum suction efficiency obtained with a mouth/squeeze structure suction nozzle can be obtained.

[Modification]
The present invention is not limited to the above-described embodiments, and includes modifications within the scope of achieving the object of the present invention.
For example, in the above embodiment, the suction nozzle and the pneumatic unloader for sucking feed for aquaculture are described, but when sucking granules with a minimum dimension of 2 mm or more, it is limited to feed for aquaculture. It can be applied to suction various cargo such as wood pellets.

In addition, in the above embodiment, the inner cylinder 31 and the outer cylinder 32 are straight tubular cylinders, but the present invention is not limited to this. That is, in the present invention, the inner cylinder and the outer cylinder may each include a bent part in the middle of the length direction, or may be a square tube, as long as the inner diameter is constant.

INDUSTRIAL APPLICABILITY The present invention relates to a suction nozzle and a pneumatic unloader, and can be suitably used for supplying feed and unloading wood pellets and the like in an aquaculture system.

DESCRIPTION OF SYMBOLS 100... Aquaculture system, 10... Feeding apparatus, 11... Storage tank, 110... Supply part, 12... Conveyance pipe, 13... Airflow generator, 20... Pneumatic unloader, 21... Separator, 22... Vacuum blower, 23... Conveyance Tube 30 Suction nozzle 31 Inner cylinder 310 Granule flow path 312 Inner cylinder tip 31a Grain inlet 32 Outer cylinder 320 Air flow path 321 Outer cylinder proximal end Portion 322 Outer cylinder tip 32a Air inlet 32b Air outlet 40 Structure 5 Ship 50 Suction nozzle C Shaft D Inner diameter dp Pellet diameter , lp... length of pellet, P... bed of granules, pt... pellet, rf... radius of pellet flow.

Claims (9)

A suction nozzle for sucking granules with a minimum dimension of 2 mm or more,
an inner cylinder in which a granule flow path for circulating the granules is formed;
an outer cylinder arranged coaxially with the inner cylinder so as to surround the inner cylinder and having an air flow path for circulating air between the outer cylinder and the outer peripheral surface of the inner cylinder;
The inner cylinder and the outer cylinder each have a constant inner diameter,
The tip of the inner cylinder forming the inlet of the granule channel is arranged to protrude from the tip of the outer cylinder forming the outlet of the air channel,
When the inner diameter of the inner cylinder is D, the axial distance from the tip of the outer cylinder to the tip of the inner cylinder is greater than 0 and is set to a range of 1.00D or less,
A ratio of the cross-sectional area of the air flow path to the cross-sectional area of the particle flow path is set within a range of 0.17 or more and 0.50 or less.
A suction nozzle characterized by: The suction nozzle according to claim 1 , wherein
The suction nozzle, wherein the distance from the tip of the outer cylinder to the tip of the inner cylinder is set within a range of 0.17D or more and 0.83D or less. In the suction nozzle according to claim 2 ,
The suction nozzle, wherein the ratio of the cross-sectional area of the air flow path to the cross-sectional area of the particle flow path is set within a range of 0.20 or more and 0.40 or less. In the suction nozzle according to any one of claims 1 to 3 ,
The suction nozzle, wherein the distance from the tip of the outer cylinder to the tip of the inner cylinder is set within a range of 0.17D or more and 0.67D or less. The suction nozzle according to claim 4 ,
The suction nozzle, wherein the ratio of the cross-sectional area of the air flow path to the cross-sectional area of the particle flow path is set within a range of 0.25 or more and 0.33 or less. A pneumatic unloader comprising the suction nozzle according to any one of claims 1 to 5 . A granule suction method for sucking granules having a minimum dimension of 2 mm or more using a suction nozzle,
The suction nozzle is arranged coaxially with the inner cylinder so as to surround the inner cylinder and the inner cylinder, in which a granule flow path for circulating the granules is formed, and the outer peripheral surface of the inner cylinder. an outer cylinder in which an air flow path for circulating air is formed,
The inner cylinder and the outer cylinder each have a constant inner diameter,
The tip of the inner cylinder forming the inlet of the granule channel is arranged to protrude from the tip of the outer cylinder forming the outlet of the air channel,
When the inner diameter of the inner cylinder is D, the axial distance from the tip of the outer cylinder to the tip of the inner cylinder is greater than 0 and is set to a range of 1.00D or less,
A granule sucking method, wherein the granules are sucked in a state in which the tip end portion of the inner cylinder and the tip end portion of the outer cylinder of the suction nozzle are arranged in a granule layer of the granules. A suction nozzle used in the granule suction method according to claim 7,
The suction nozzle, wherein the outer cylinder is attached to the inner cylinder with the distance set within the range. A suction nozzle for sucking granules with a minimum dimension of 2 mm or more,
an inner cylinder in which a granule flow path for circulating the granules is formed;
an outer cylinder arranged coaxially with the inner cylinder so as to surround the inner cylinder and having an air flow path for circulating air between the outer cylinder and the outer peripheral surface of the inner cylinder;
The inner cylinder and the outer cylinder each have a constant inner diameter,
The tip of the inner cylinder forming the inlet of the granule channel is arranged to protrude from the tip of the outer cylinder forming the outlet of the air channel,
When the inner diameter of the inner cylinder is D, the axial distance from the distal end of the outer cylinder to the distal end of the inner cylinder is set in the range of 0.17D or more and 1.00D or less.
A suction nozzle characterized by:

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