JP2021001034A - Suction nozzle and pneumatic unloader - Google Patents

Abstract

To provide a suction nozzle having a simplified structure without lowering suction efficiency.SOLUTION: A suction nozzle 30 of the present invention that sucks particles having a minimum size of 2 mm or more includes an inner cylinder 31 in which a particle flow path 310 for circulating the particles is formed, and an outer cylinder 32 that is arranged coaxially with the inner cylinder 31 so as to surround the inner cylinder 31 and has an air flow path 320 for circulating air formed between an outer peripheral surface of the inner cylinder 31 and itself, in which the inner cylinder 31 and the outer cylinder 32 each have a constant inner diameter. An inner cylinder tip 312 forming a particle inflow port 31a of the particle flow path 310 is arranged so as to protrude from an outer cylinder tip 322 forming an air outflow port 32b of the air flow path 320, and an axial distance from the outer cylinder tip 322 to the inner cylinder tip 312 is set to a range larger than 0 and 1.00D or less when the inner diameter of the inner cylinder 31 is D.SELECTED DRAWING: Figure 2

Description

The present invention relates to a suction nozzle and a pneumatic unloader.

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

In recent years, wood pellets and high-density semi-carbonized wood pellets, which have been treated in the same way as fossil fuels in energy trading, are also being imported from overseas as domestic consumption increases. .. Currently, container transportation is the mainstream, but bulk carrier transportation is also increasing, and the use of pneumatic unloaders is expected to increase.

Generally, a pneumatic unloader is used for unloading cargo (wheat, etc.) of a ship, and includes a vacuum blower, a transport pipe connected to the vacuum blower, and a suction nozzle connected to the tip of the transport pipe. ing. At the time of unloading, the suction nozzle is inserted into the cargo handling object on the ship from above, and the cargo handling object is sucked up by the suction force of the vacuum blower. The cargo handling material sucked into the suction nozzle is air-conveyed in the transport pipe and stored in a tank or the like on land. Compared to other grab bucket type and mechanical type unloaders, such a pneumatic unloader may have restrictions on the lift, but there is no big difference in the required power, and the structure as a cargo handling machine is simple. The bulk ship side also has features such as no special modification required.

The suction nozzle used in the pneumatic unloader as described above is provided with an outer cylinder and an inner cylinder constituting a double pipe structure, and the suction efficiency of the cargo handling object sucked by the inner cylinder is controlled by the outer cylinder and the inner cylinder. It is improved by the secondary air flow generated between the above (see, for example, Patent Document 2).
Further, in such a suction nozzle, a "bell mouth / diaphragm structure" that forms a three-dimensional curved surface in which the inner tube has a bell mouth shape and the outer tube has a diaphragm shape has been conventionally adopted. This is because the "bell mouth / squeezing structure suction nozzle" has a higher suction efficiency than the "straight tube / straight tube structure" suction nozzle, which has a straight tube shape for the inner and outer tubes. Is based on the finding that can be aspirated (see, for example, Non-Patent Document 1).

JP-A-2018-11572 Japanese Unexamined Patent Publication No. 2013-159468

Takeshi Kano, "Study on Improvement of Performance of Powder and Granule Suction Nozzle" Chemical Engineering Papers Vol. 10, No. 2 (1984)

However, the above-mentioned Non-Patent Document 1 demonstrates the suction efficiency of the suction nozzle when sucking powder or granular material having a diameter of about 1 mm, but the non-Patent Document 1 for granules such as feed for cultivation and wood pellets. It has a larger diameter than the powder or granular material disclosed in. That is, conventionally, the suction efficiency of the suction nozzle when sucking granules such as aquaculture feed and wood pellets has not been sufficiently studied.
Further, since the suction nozzle having a bell mouth / aperture structure conventionally adopted forms a complicated three-dimensional curved surface, it is difficult to manufacture or repair the suction nozzle.

An object of the present invention is to provide a suction nozzle and a pneumatic unloader capable of simplifying the structure of particles having a minimum size of 2 mm or more without lowering the suction efficiency.

The present invention is a suction nozzle that sucks particles having a minimum size of 2 mm or more, and has an inner cylinder in which a particle flow path for circulating the particles is formed inside, and the inner cylinder so as to surround the inner cylinder. The inner cylinder and the outer cylinder are provided with an outer cylinder which is arranged coaxially with the inner cylinder and forms an air flow path for passing air between the inner cylinder and the outer peripheral surface of the inner cylinder. The inner cylinder tip portion forming the inflow port of the particle flow path is arranged so as to protrude from the outer cylinder tip portion forming the outflow port of the air flow path, and when the inner diameter of the inner cylinder is D, the said The axial distance from the tip of the outer cylinder to the tip of the inner cylinder is set to a range larger than 0 and 1.00 D or less.
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 or the like.

Since the suction nozzle of the present invention has a constant inner diameter of each of the inner cylinder and the outer cylinder, it forms a simple three-dimensional shape as compared with the conventional suction nozzle having a bell mouth / drawing structure.
Further, the suction nozzle of the present invention sucks the 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. To do. At this time, an air flow that sucks the particles of the granular material layer is generated in the granular material flow path of the inner tube, and the inflow port (grains) of the granular material flow path is in the air flow path between the inner cylinder and the outer cylinder. A secondary air flow is generated due to the suction force generated near the body inflow port).
Here, the tip of the inner cylinder forming the particle inlet is arranged so as to protrude by an appropriate distance from the tip of the outer cylinder forming the outlet (air outlet) of the air flow path. Therefore, the secondary air flow flowing out from the air outlet can permeate a wide range of the grain layer, and the grain layer can be fluidized in a wide range.
In addition, since the secondary air flow permeates a wide range of the granular material layer, the force (pushing force) that the secondary air flow pushes each particle toward the central axis of the suction nozzle becomes small, and the particle flow path. The diameter of the flux of the granules flowing through the water can be increased. As a result, the suction efficiency of the granules can be increased. Further, since it is difficult for the granular material having the minimum size of 2 mm or more to ride on the secondary air flow as compared with the granular material having the minimum size of 1 mm or less, which is the target of the conventional suction nozzle, the effect of reducing the pushing force is reduced. Is larger than before.
As a result, the suction nozzle of the present invention can suck particles having a minimum size of 2 mm or more with a suction efficiency as high as or higher than the suction efficiency of the conventional suction nozzle.
Therefore, according to the present invention, even when a particle having a minimum size of 2 mm or more is sucked, a suction nozzle capable of simplifying the structure without lowering the suction efficiency is provided, and the suction nozzle can be easily manufactured and repaired.

In the 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 grain flow path is preferably set in the range of 0.17 or more and 0.50 or less.
According to such a configuration, the suction efficiency of the granules can be improved.
In the present invention, the cross-sectional area of the granular material flow path and the cross-sectional area of the air flow path refer to the cross-sectional area orthogonal to the flow direction of the granular material and air in each flow path.

In the suction nozzle of the present invention, the distance from the tip of the outer cylinder to the tip of the inner cylinder is preferably set in the 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 grain flow path is set in the range of 0.20 or more and 0.40 or less. preferable.
According to such a configuration, the suction efficiency of the granules can be further improved.

In the suction nozzle of the present invention, the distance from the tip of the outer cylinder to the tip of the inner cylinder is preferably set in the 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 grain 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 granules can be most improved.

The pneumatic unloader of the present invention is characterized by including the suction nozzle described above. As a result, the same effect as the effect of the suction nozzle of the present invention described above is obtained.

According to the present invention, it is possible to provide a suction nozzle and a pneumatic unloader capable of simplifying the structure without lowering the suction efficiency for particles having a minimum size of 2 mm or more.

The schematic diagram which shows a part of the aquaculture system of one Embodiment of this invention. The cross-sectional view which shows the suction nozzle of the said embodiment. A graph showing the relationship between the amount of displacement at the tip of the double pipe and the solid-air ratio. The graph which shows the relationship between the double pipe cross-sectional area ratio and the solid-gas ratio. The graph which shows the relationship between the diameter of a pellet and the solid-gas ratio. The schematic diagram which shows the movement of the pellet sucked by a suction nozzle. The schematic diagram which shows the movement of the pellet sucked by a suction nozzle. The schematic diagram which shows the movement of the pellet sucked by a suction nozzle. Sectional drawing which shows the conventional suction nozzle.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[Aquaculture system 100]
In FIG. 1, the aquaculture system 100 is installed at sea, a plurality of cages (not shown), a feeding device 10 for supplying feed to these cages, a pneumatic unloader 20 for supplying feed to the feeding device 10. It includes a structure 40.

The feeding device 10 includes a storage tank 11 for storing granular feed, a transport pipe 12 from the storage tank 11 to the cage, and an airflow generator 13 for forming a transport airflow inside the transport pipe 12.
The storage tank 11 is installed in a portion of the structure 40 on the sea surface. Further, the storage tank 11 is composed of a so-called hopper or the like, and can store granular feed inside and can supply a predetermined amount of feed from the lower supply unit 110. One end of the transport pipe 12 is connected to the supply unit 110 of the storage tank 11, and the other end (not shown) is introduced into the cage. The airflow generator 13 is composed of an electric motor, an engine-driven air compressor, or the like, and by supplying compressed air to one end of the transport pipe 12, the feed from the supply unit 110 of the storage tank 11 is directed toward the cage. Can be transported.

The feed in this embodiment is a granular material having a minimum size 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, the diameter dp and the length lp of the pellet pt may be 2 mm or more, respectively (see FIGS. 6 to 8). On the other hand, when the feed is a granule having another shape, the minimum dimension of the shape may be 2 mm or more.

The pneumatic unloader 20 includes a separator 21 installed on the sea surface portion of the structure 40, 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 the 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 transport pipe 23. Then, 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 turret or the like, and is installed in the vicinity where the cage is placed. As shown in FIG. 1, the structure 40 may have a lower portion fixed to the seabed and an upper portion arranged on the sea surface, or may have a configuration using a floating body such as a ship or a barge.

[Suction nozzle]
The detailed structure of the suction nozzle 30 according to the present embodiment will be described.
As shown in FIG. 2, the suction nozzle 30 has a so-called double-tube structure, and air is provided between the inner cylinder 31 in which the granular material flow path 310 is formed inside and the outer peripheral surface of the inner cylinder 31. It includes an outer cylinder 32 on which the flow path 320 is formed.

The inner cylinder 31 of the present embodiment is a straight tubular cylinder, and its inner diameter is constant. The inner cylinder 31 has an inner cylinder base end portion (not shown) connected to the transport pipe 23, and an inner cylinder tip portion 312 forming the granular material inflow port 31a of the granular material flow path 310.

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

Here, the suction nozzle 30 of the present embodiment is configured as follows so as to preferably suck feed which is a grain having a minimum size of 2 mm or more.
That is, in the present embodiment, the inner cylinder tip portion 312 is arranged in a state of protruding from the outer cylinder tip portion 322 in the axis C direction, and is exposed from the outer cylinder 32. Specifically, when the inner diameter of the inner cylinder 31 is D, the distance from the outer cylinder tip portion 322 to the inner cylinder tip portion 312 in the axis C direction (double pipe tip deviation amount s) is larger than 0. And it is set to 1.00D or less.
In this embodiment, the ratio A2 / A1 (double pipe 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 grain flow path 310 is 0.17 or more and 0.50 or less. It is preferably set in the range.

Further, the amount of displacement s at the tip of the double pipe is more preferably set in the range of 0.17D or more and 0.83D or less, and the double pipe cross-sectional area ratio α in this case is 0.20 or more and 0. It is preferably set in the range of .40 or less.
Further, the amount of displacement s at the tip of the double pipe is more preferably set in the range of 0.17D or more and 0.67D or less, and the double pipe cross-sectional area ratio α in this case is 0.25 or more and 0. It is preferably set in the range of .33.

The operation of the suction nozzle 30 of the present embodiment described above will be described with reference to FIG. 8 illustrated later.
First, the suction nozzle 30 is inserted into the feed (grain layer P) from above in the vertical direction, and the inner cylinder tip portion 312 and the outer cylinder tip portion 322 are arranged in the grain layer P. In this state, when the vacuum blower 22 is driven, an updraft that sucks air and particles from the particle layer P is generated in the particle flow path 310 of the inner cylinder 31. Further, in the air flow path 320 between the inner cylinder 31 and the outer cylinder 32, a secondary air flow is generated due to the suction force generated in the vicinity of the particle inflow port 31a of the particle flow path 310. This secondary air flow flows into the air flow path 320 from the air inflow port 32a, permeates into the granular material layer P from the air outlet 32b, and then flows into the granular material inflow port 31a. The granular material layer P in the range in which the secondary air flow has penetrated is fluidized, and each granular material heads toward the granular material inflow port 31a together with the secondary air flow.

[Effect of Embodiment]
According to such an embodiment, the following effects can be 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 constitutes a straight pipe / straight pipe structure, a conventional suction nozzle composed of a bell mouth / drawing structure. Compared to, it forms a simple three-dimensional shape.
Further, in the suction nozzle 30 of the present embodiment, the inner cylinder tip portion 312 forming the granular material inflow port 31a is arranged in a state of protruding from the outer cylinder tip portion 322 forming the air outlet 32b by an appropriate distance. There is. Therefore, the secondary air flow flowing out from the air outlet 32b permeates a wide range of the grain layer P, and the grain layer P can be fluidized in a wide range.
Further, as the secondary air flow permeates the granular material layer P in a wide range, the force (pushing force) that the secondary air flow pushes each grain toward the axis C becomes small, and the particle flow path 310 is formed. The diameter of the flux of the flowing particles (for example, the pellet flow radius rf in FIG. 8) becomes large. As a result, the suction efficiency of the granules can be increased. Further, since it is difficult for the granular material having the minimum size of 2 mm or more to ride on the secondary air flow as compared with the granular material having the minimum size of 1 mm or less, which is the target of the conventional suction nozzle, the effect of reducing the pushing force is reduced. Is larger than before.
Therefore, the suction nozzle 30 of the present embodiment can suck particles having a minimum size of 2 mm or more with a suction efficiency as high as or higher than the suction efficiency of the conventional suction nozzle.
Therefore, according to the present embodiment, there is provided a suction nozzle 30 that does not reduce the suction efficiency and has a simplified structure when sucking particles having a minimum size of 2 mm or more, and manufactures or repairs 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 above-mentioned ranges.
The suction efficiency of the granules will be described in detail with reference to Examples described later.

Next, Examples and Comparative Examples of the present invention will be described. For the components corresponding to the above-described embodiment, the same reference numerals as those in the above-described embodiment 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 for sucking pellets (granular materials) as feed was conducted using this suction tester. In this test, the test time was set to 1 minute or more, the amount of air sucked into the suction nozzle 30 and the amount of pellets were measured, respectively, and the solid-air ratio (pellet amount (t) / air amount (t)) was calculated. ..

The lift from the suction nozzle 30 to the separator 21 was about 14 m, and the speed of the pellets to be conveyed was about 10 m / sec.
Further, as the vacuum blower 22 used in the suction tester, a blower having a static pressure of −95 kPa and a maximum air volume of 20 Nm3 / min with an air volume-static pressure characteristic was used. When the air volume was insufficient, two of the same blowers were connected in parallel for operation.
The pellets used this time have a true specific gravity in the range of 1.15 to 1.40 and an average value of 1.30. The bulk density of the pre-tapping pellets ranged from 0.61 to 0.72, with an average value of 0.66. The bulk density of the pellets after tapping was in the range of 0.66 to 0.74, and the average value was 0.70.
Further, the inner diameter of the inner cylinder of the double tube nozzle was set to φ155 with 10 times the pellet diameter as a guide so that pellets having a maximum diameter of φ16 could be sucked stably.

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

In each of the following embodiments, the amount of displacement s at the tip of the double pipe in a state where the inner cylinder 31 protrudes from the outer cylinder 32 is set as a positive value, and the outer cylinder 32 protrudes from the inner cylinder 31. The double pipe tip deviation rate s / D, which is the ratio of the double pipe tip deviation amount s to the inner diameter D of the inner cylinder 31, was calculated with the double pipe tip deviation amount s as a negative value. The same applies to each comparative example.
Further, in Examples 1 to 3, the case where the double pipe tip deviation rate s / D is in the range of 0.00 to 1.00 is included in the range of the present invention.
Further, in Comparative Examples 1 to 3, when s / D = 0 (s = 0), the curved surface of the inner cylinder 51 and the outer cylinder 52 interfere with each other, so the test is not performed.

FIG. 3 is a graph showing the test results (Examples 1 to 3) shown in Table 1.
As shown in FIG. 3, even in Example 1 showing a tendency for the solid-gas ratio to be low among Examples 1 to 3, the double pipe tip deviation rate s / D is in the range of 0.00 to 1.00. In this case, a solid-air ratio of at least about 10 was obtained.
Specifically, in Example 1, while the double pipe tip displacement rate s / D increases from -0.5 to 0 in 0.17 increments, the solid-state ratio is approximately double or more. It is increasing rapidly. Further, while the double pipe tip deviation rate s / D increases from 0 to 1.0, the solid air ratio is gradual, peaking at the double pipe tip deviation rate s / D of 0.50. When it changes in a mountainous manner and the deviation rate s / D at the tip of the double pipe becomes larger than 1.0, the solid-air ratio is greatly reduced.
Although the data in Table 1 is omitted, the above-mentioned tendency in Example 1 is the same in Examples 2 and 3, and the solid-gas ratio has a double pipe tip deviation rate s / D of 0. In the range of .00 to 1.00, it changed at a higher level than in the other ranges.
Further, as shown in FIG. 3, according to Examples 1 to 3, the deviation rate s / D at the tip of the double pipe is preferably in the range of 0.17 to 0.83, and 0.17 to 0. It was found that the range of 67 is more preferable, and 0.5 is the most preferable.

On the other hand, in Comparative Examples 1 to 3, if the conditions of the double pipe cross-sectional area ratio α are the same as those of Examples 1 to 3, in all the ranges tested for the double pipe tip deviation ratio s / D. , The solid-air ratio became smaller than that of Examples 1 to 3 (see Table 1).
In particular, in Comparative Example 1 which shows a tendency that the solid air ratio is low among Comparative Examples 1 to 3, in order to obtain a solid air ratio of at least about 10, the double pipe tip deviation rate s / D is 0.17 to 1. It needed to be in the range of 0.83.

Moreover, the maximum solid-state 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 the suction nozzle having a bell mouth / drawing structure is about 1/3 (about 0.33), and therefore, Comparative Examples 1 to 3 It is considered that the maximum solid-air ratio of about 20 obtained from the above is the maximum solid-air ratio of the bell mouth / squeezed structure obtained in this test.
On the other hand, in Examples 2 and 3, when the deviation rate s / D at the tip of the double pipe is in the range of 0.17 to 0.67, the maximum solid air ratio obtained in Comparative Examples 1 to 3 ( A solid-air ratio equal to or higher than (around 20) was obtained.

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

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

(Pellet diameter)
Next, in Examples 1 to 10 described above, the conditions under which a relatively high solid air ratio was obtained (double pipe tip displacement ratio s / D: 0.50, double pipe cross-sectional area ratio α: 0.25). ) Was used for a straight pipe / straight pipe structure suction nozzle 30 (Example), and the change in the solid-gas ratio when the diameter of the pellet was changed was investigated. Further, in Comparative Examples 1 to 3, it has the condition that a relatively high solid air ratio was obtained (double pipe tip deviation ratio s / D: 0.50, double pipe cross-sectional area ratio α: 0.33). Using a suction nozzle 50 (comparative example) having a bell mouth / drawing structure, the change in the solid-gas ratio when the diameter of the pellet was changed was examined in the same manner as described above. These results are shown in FIG.
The diameter of the pellet is the minimum size of the pellet.

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

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

(Observation and simulation)
Next, in order to investigate the effect of the amount of displacement s at the tip of the double tube on the suction efficiency of the pellets, a test was conducted in which the pellets in the suction nozzle 30 were observed. In this test, the suction nozzle 30 is divided and a transparent panel is provided to visualize the inside of the suction nozzle 30, and the pellet pt (FIGS. 6 to 8) passes through the particle flow path 310 in the inner cylinder 31. The radius (pellet flow radius rf) centered on the axis C of the flux (see) was measured. The diameter dp (minimum dimension) of the pellets used is 8 mm.

6 to 8 show a suction nozzle 30 divided into 1/4 about the axis C, and a pellet layer P of pellets pt filled around the suction nozzle 30. In addition, although some pellets pt constituting the grain layer P are illustrated in FIGS. 6 to 8, most of the pellets are simplified.

In the suction nozzles 30 shown in FIGS. 6 to 8, the double pipe cross-sectional area ratio α is set to a common value (0.33), and the double pipe tip deviation ratio s / D is 0 to 0.33. The values are set to different values in the range.
As shown in FIG. 6, when the double pipe tip deviation rate s / D was 0, the pellet flow radius rf was about 31% with respect to the inner diameter D of the inner cylinder 31.
As shown in FIG. 7, when the double pipe tip deviation ratio s / D is 0.17, the pellet flow radius rf is about 55% with respect to the inner diameter D of the inner cylinder 31, which is shown in FIG. It was higher than the case.
As shown in FIG. 8, when the double pipe tip deviation rate s / D is 0.33, the pellet flow radius rf is about 68% with respect to the inner diameter D of the inner cylinder 31, which is the highest. ..
Although not shown, when the deviation rate s / D at the tip of the double pipe is 0.50, the pellet flow radius rf is about 66% with respect to the inner diameter D of the inner cylinder 31.
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 has changed due to the change in the displacement rate s / D at the tip of the double pipe, and the change correlates with the solid air ratio. It turned out to have a relationship. That is, it was found that the solid-gas ratio increases as the pellet flow radius rf increases.

Here, the results of simulation analysis of the secondary air flow near the suction nozzle 30 and the movement of the pellet pt are shown by arrows in FIGS. 6 to 8. In FIGS. 6 to 8, the arrow (thin) indicates the direction of the secondary air flow, and the arrow (thick) indicates the locus of the pellet pt existing near the tip of the suction nozzle 30.

As shown in FIGS. 6 to 8, as the deviation rate s / D at the tip of the double tube increases, the region R of the secondary air flow penetrating into the grain layer P expands. Specifically, the maximum distance DR from the axis C in the radial direction of the suction nozzle 30 to the boundary of the region R of the secondary air flow is the largest in the case shown in FIG.
When the region R of the secondary air flow penetrating into the grain layer P expands in this way, the horizontal component of the secondary air flow in this region R becomes smaller, so it is considered that the force pushing the pellet pt in the horizontal direction becomes smaller. Be done. Then, it is considered that when the force for pushing the pellet pt in the horizontal direction becomes smaller, the amount of movement of the pellet pt in the horizontal direction becomes smaller and the pellet flow radius rf becomes larger.
Further, the pellet pt has a minimum size of 2 mm or more, and has a larger inertial force than a particle having a diameter of 1 mm or less, which is a target of a conventional suction nozzle, so that it is difficult to ride on a secondary air flow. Therefore, in order to increase the pellet flow radius rf when sucking pellet pt having a minimum size of 2 mm or more, it is considered more important than before to reduce the above-mentioned "force to push the pellet in the horizontal direction". Be done.
However, if the region R of the secondary air flow becomes larger than a certain level, it is considered that the force for fluidizing the pellet pt is weakened.
According to the above observations and simulations, it was found that the pellet flow radius rf can be appropriately increased by appropriately setting the double pipe tip deviation rate s / D, and thus the solid-gas ratio can be improved. It was.

(Summary)
In the prior art, it was thought that a bell mouth / drawing structure could obtain higher suction efficiency than a straight tube / straight tube structure as the shape of the suction nozzle, but according to the above-described embodiment, the minimum number of pellets was obtained. It was clarified that when the size is 2 mm or more, a higher suction efficiency can be obtained in the straight tube / straight tube structure than in the bell mouth / drawing structure.
Further, according to the above-described embodiment, by setting the double pipe tip deviation ratio s / D and the double pipe cross-sectional area ratio α in the suction nozzle 30 of the straight pipe / straight pipe structure in a suitable range, the bell It was clarified that a suction efficiency equal to or higher than the maximum suction efficiency obtained with a suction nozzle having a mouse / squeezing structure can be obtained.

[Modification example]
The present invention is not limited to the above-described embodiment, and modifications within the range in which the object of the present invention can be achieved are included in the present invention.
For example, in the above-described embodiment, the suction nozzle for sucking the feed for aquaculture and the pneumatic unloader are described, but the feed for aquaculture is limited to the case where particles having a minimum size of 2 mm or more are sucked. However, it can be applied when sucking various cargo handling objects such as wood pellets.

Further, in the above embodiment, the inner cylinder 31 and the outer cylinder 32 are straight tubular cylinders, respectively, but the present invention is not limited to this. That is, in the present invention, the inner cylinder and the outer cylinder may include a bent portion in the middle in 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 feeding feed in aquaculture system and unloading wood pellets and the like.

100 ... culture system, 10 ... feeding device, 11 ... storage tank, 110 ... supply unit, 12 ... transport pipe, 13 ... airflow generator, 20 ... pneumatic unloader, 21 ... separator, 22 ... vacuum blower, 23 ... transport 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 base end Part 322 ... Outer cylinder tip, 32a ... Air inlet, 32b ... Air outlet, 40 ... Structure, 5 ... Ship, 50 ... Suction nozzle, C ... Shaft, D ... Inner cylinder inner diameter, dp ... Pellet diameter , Lp ... pellet length, P ... grain layer, pt ... pellet, rf ... pellet flow radius.

Claims (7)

A suction nozzle that sucks particles with a minimum size of 2 mm or more.
An inner cylinder in which a particle flow path for circulating the particles is formed inside, and
It is provided with an outer cylinder which is arranged coaxially with the inner cylinder so as to surround the inner cylinder and in which an air flow path for passing air is formed between the inner 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 granular material flow path is arranged so as to protrude from the tip of the outer cylinder forming the outlet of the air flow path.
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 set to a range larger than 0 and 1.00 D or less. Characterized suction nozzle. In the suction nozzle according to claim 1,
A suction nozzle characterized in that the ratio of the cross-sectional area of the air flow path to the cross-sectional area of the grain flow path is set in the range of 0.17 or more and 0.50 or less. In the suction nozzle according to claim 1 or 2.
A suction nozzle characterized in that the distance from the tip of the outer cylinder to the tip of the inner cylinder is set in the range of 0.17D or more and 0.83D or less. In the suction nozzle according to claim 3,
A suction nozzle characterized in that the ratio of the cross-sectional area of the air flow path to the cross-sectional area of the granular material flow path is set in the range of 0.20 or more and 0.40 or less. In the suction nozzle according to any one of claims 1 to 4.
A suction nozzle characterized in that the distance from the tip of the outer cylinder to the tip of the inner cylinder is set in the range of 0.17D or more and 0.67D or less. In the suction nozzle according to claim 5,
A suction nozzle characterized in that the ratio of the cross-sectional area of the air flow path to the cross-sectional area of the granular material flow path is set in the 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 6.

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