JP7068123B2 - Pipe members, sand recovery systems, and sand recovery vessels - Google Patents

Description

The present invention relates to a pipe member, a sand recovery system, and a sand recovery ship.

When there is a landfill site nearby, the earth and sand generated by dredging work in harbors, rivers, lakes and marshes is often sent to the landfill site and reused as landfill earth and sand. If there is no landfill near the dredging work site, it is necessary to carry the dredged soil to a remote landfill or dumping site. On the other hand, the dredged earth and sand contains sand that can be reused for construction and civil engineering work.

Therefore, if sand is collected from the earth and sand generated during the dredging work and reused near the dredging work site, and the remaining mud is transported to a remote landfill site or dumping site, the amount of transportation will be increased. Since it is reduced, it is possible to reduce the transportation cost. In addition, since the sand is collected from the earth and sand generated by the dredging work and only the remaining mud is disposed of, the amount of disposal is reduced and the life of the earth dumping site can be extended.

For example, in Patent Document 1, a coarse classification means for separating mud water, which is a mixture of dredged earth and sand containing sand and water, into coarse particles and fine particles in the middle of a mud feed pipe transported by a pump. Further, a method of mixing diluted water with highly sand-containing muddy water and precipitating the highly sand-containing muddy water in a precipitation classification tank is disclosed.

Japanese Unexamined Patent Publication No. 2004-097873

However, in the invention described in Patent Document 1, the structure of the coarse classification means for separating the coarse particles and the fine particles provided in the middle of the mud feeding pipe is complicated, and the sand content is settled in the settling tank. The process is complicated because it is made to work.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to propose a pipe member having an easy structure for recovering sand from dredged earth and sand.

In order to achieve the above object, the pipe member according to the present invention has a pump connection portion connected to a pump for pumping earth and sand water containing sand, a pump connection portion at one end, and a diameter of the first diameter. It has a first pipe portion and a second pipe portion connected to the other end of the first pipe portion and having a second diameter larger than the first diameter, and the second pipe portion has an inner wall. It is characterized by forming one or more through holes that penetrate the outer wall and discharge the sand contained in the earth and sand water pumped from the pump.

Further, it is preferable that the pipe member according to the present invention further has a third pipe portion which is connected to the other end of the second pipe portion and has a third diameter smaller than the second diameter.

Further, it is preferable that the pipe member according to the present invention further has an obstacle plate arranged so as to stand up from the inner wall of the second pipe portion on the downstream side of at least one of the single or a plurality of through holes.

The sand recovery system according to the present invention has a pump that pumps sand-containing sediment water, a pipe member that is connected to the pump and discharges sand contained in the sediment water pumped from the pump, and a pipe member that discharges sand. It has a recovery device for collecting sand, and the pipe member has a pump connection portion connected to a pump for pumping earth and sand water containing sand, and a pump connection portion is arranged at one end and has a first diameter. The second pipe portion has a first pipe portion having a diameter and a second pipe portion having a second diameter connected to the other end of the first pipe portion and having a diameter larger than the first diameter. It is characterized in that one or more through holes are formed which penetrate from the inner wall to the outer wall and discharge the sand contained in the earth and sand water pumped from the pump.

Further, in the sand recovery system according to the present invention, it is preferable that the discharge pressure is adjusted so that the flow velocity of the earth and sand water flowing through the second pipe portion is 0.7 m / sec or more and 3.0 m / sec or less.

The sand recovery ship according to the present invention has a pump that pumps sand-containing sediment water, a pipe member that is connected to the pump and discharges sand contained in the sediment water pumped from the pump, and a pipe member that discharges sand. It has a recovery device for collecting sand, and the pipe member has a pump connection portion connected to a pump for pumping earth and sand water containing sand, and a pump connection portion is arranged at one end and has a first diameter. The second pipe portion has a first pipe portion having a diameter and a second pipe portion having a second diameter connected to the other end of the first pipe portion and having a diameter larger than the first diameter. It is characterized in that one or more through holes are formed which penetrate from the inner wall to the outer wall and discharge the sand contained in the earth and sand water pumped from the pump.

According to the pipe member according to the present invention, sand can be efficiently recovered from earth and sand water.

It is a figure explaining the outline of an example of a sand recovery system. It is a figure explaining the outline of an example of a pipe member 3, (a) is a side view of a pipe member, and (b) is a sectional view of a pipe member 3 in a plan view. It is a figure which shows an example of the steel pipe joint which has a through hole, (a) is the figure which shows the state which two main steel pipes are connected by the steel pipe joint, (b) is the front surface of the steel pipe joint which has a through hole. It is a figure, (c) is a cross-sectional view in the AA'plane shown in (b). 3 is a view showing an example of a steel pipe joint having a baffle plate in front of a through hole of the steel pipe joint shown in FIG. 3, FIG. 3A is a front view of a steel pipe joint having a baffle plate, and FIG. 3B is a front view. It is a cross-sectional view in the AA'plane shown in (a), and (c) is a cross-sectional view in the BB'plane shown in (a). It is a figure which shows the outline of the experiment of the pipe member which concerns on this invention. It is a figure which showed the sand recovery rate (weight ratio) for each through hole when the flow velocity in the 2nd pipe part was changed, and in (a), the flow velocity in the 2nd pipe part was 0.7m / sec, and ( In b), the flow velocity in the second pipe portion is 0.8 m / sec, in (c) the flow velocity in the second pipe portion is 0.9 m / sec, and in (d), the flow velocity in the second pipe portion is 1. It is 0 m / sec. It is a figure which compared the sand recovery rate (weight ratio) for each through hole with respect to the 1st earth and sand water when the obstruction plate was not provided, and the flow velocity in the 2nd pipe part is 0.85m in (a). It is / sec, and in (b), the flow velocity in the second pipe portion is 0.95 m / sec, and in (c), the flow velocity in the second pipe portion is 1.05 m / sec. It is a figure which compared the sand recovery rate (weight ratio) for each through hole with respect to the 2nd earth and sand water when the obstruction plate was not provided, and the flow velocity in the 2nd pipe part is 0.85m in (a). It is / sec, and in (b), the flow velocity in the second pipe portion is 1.0 m / sec, and in (c), the flow velocity in the second pipe portion is 1.1 m / sec. It is a figure which compared the sand recovery rate (weight ratio) for each through hole with respect to the 3rd earth and sand water when the obstruction plate was not provided, and the flow velocity in the 2nd pipe part is 0.8m in (a). It is / sec, and in (b), the flow velocity in the second pipe portion is 1.0 m / sec, and in (c), the flow velocity in the second pipe portion is 1.1 m / sec. It is a figure explaining the outline of an example of a sand recovery ship.

Hereinafter, the pipe member, the sand recovery system, and the sand recovery ship according to one aspect of the present disclosure will be described with reference to the drawings. However, it should be noted that the technical scope of the present disclosure is not limited to those embodiments, but extends to the inventions described in the claims and their equivalents. In the following description and figures, components having the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

(Overview of the sand recovery system according to the present invention)
FIG. 1 is a diagram illustrating an outline of an example of a sand recovery system according to an embodiment.

The sand recovery system 1 is a pump 2 for pumping earth and sand water containing sand, a pipe member 3 connected to a pump 2 for pumping earth and sand water containing sand, and a recovery device for transporting sand discharged by the pipe member 3. Has 4 and. For example, the pump 2 sucks up the earth and sand water from the water tank 5 storing the earth and sand water in which the earth and sand including the dredged sand and the seawater or fresh water are mixed, and pumps the earth and sand water to the pipe member 3.

The pipe member 3 is a device for separating sand from the earth and sand water pumped from the pump 2 and discharging it to the outside of the pipe. The pipe member 3 is connected to a pump connection portion 30 connected to a pump 2 for pumping earth and sand water, a first pipe portion 31 to which a pump connection portion 30 is connected to one end, and the other end of the first pipe portion 31. It has a second pipe portion 32. Further, the pipe member 3 may have a third pipe portion 33 connected to the other end of the second pipe portion 32.

The earth and sand water containing sand discharged from the pump 2 passes through the pump connection portion 30 and flows into the first pipe portion 31. The earth and sand water pumped from the pump 2 passes through the first pipe portion at a first flow velocity at which the earth and sand do not settle. It should be noted that the speed at which the sediment in the sediment water in the pipe may settle, accumulate, or stand still and block the inside of the pipe is called the limit flow velocity. Therefore, the first flow velocity is faster than the critical flow velocity. The diameter of the second pipe portion 32 connected to the other end of the first pipe portion is larger than the diameter of the first pipe portion 31.

The amount of sediment water flowing through the first pipe portion 31 per unit time is the product of the pipe cross-sectional area of the first pipe portion 31 and the first flow velocity, and the amount of sediment water flowing through the second pipe portion 32 per unit time is the second. It is the product of the pipe cross-sectional area of the pipe portion 32 and the first flow velocity. The diameter of the second pipe portion 32 is larger than the diameter of the first pipe portion 31. Further, the entire amount of earth and sand water flows from the first pipe portion 31 into the second pipe portion 32. Therefore, the earth and sand water that has passed through the first pipe portion 31 at the first flow velocity will flow through the second pipe portion 32 at a second flow velocity slower than the first flow velocity. The discharge pressure of the pump 2 is adjusted so that the first flow velocity and the second flow velocity become equal to or higher than the limit flow velocity.

Further, according to Bernoulli's theorem regarding fluid, when sediment water, which is a non-compressible fluid, flows from the first pipe portion 31 having a small diameter to the second pipe portion 32 having a large diameter, the water pressure of the sediment water with respect to the inner wall of the pipe A certain static pressure is higher in the second pipe portion 32 than in the first pipe portion 31. Therefore, since the static pressure of the earth and sand water on the inner wall of the second pipe portion 32 becomes high, if a through hole penetrating from the inner wall of the second pipe portion 32 to the outer wall is appropriately provided, the earth and sand water will be discharged to the outside of the second pipe portion 32. It becomes easy to be discharged.

The earth and sand water, which was in a state where sand and mud were mixed and flowed in the first pipe portion 31, flows through the second pipe portion 32 at a second flow velocity slower than the first flow velocity. The sediment water having a slow flow velocity begins to separate into a lower running water layer having a large particle size and containing a large amount of heavy sand and an upper running water layer having a small particle size and containing a large amount of mud, and flows through the second pipe portion 32.

Therefore, by providing a single or a plurality of singular or a plurality of through holes 321 to 325 on the ground side of the second pipe portion 32 through which the sand-rich running water layer flows, a part of the sand-rich running water layer is removed from the pipe. The sand is discharged, and the sand recovery system 1 can recover the sand contained in the earth and sand water.

A third pipe portion 33 having a diameter smaller than that of the second pipe portion 32 is connected to the opposite side of the second pipe portion 32 connected to the first pipe portion 31. Through the third pipe portion 33, sediment water containing a large amount of mud after the sand has been collected can be sent to, for example, a landfill.

The sand recovery system 1 has a recovery device 4 parallel to the pipe member 3 on the lower side of the pipe member 3, that is, on the ground side. For example, the recovery device 4 has a belt conveyor 41 having a mesh belt and a vibrating sieve 42. The earth and sand water containing a large amount of sand discharged from the single or a plurality of through holes 321 to 325 of the pipe member 3 falls on the mesh belt, the water escapes downward, and the sand having a low water content is removed by the belt conveyor 41. Be transported. Moisture is further removed from the transported sand by the vibrating sieve 42. The sand is transported to the sand reclamation site by, for example, a soil carrier (not shown).

Further, the recovery device 4 may have a gutter provided in parallel with the lower side of the pipe member 3 and inclined toward the connection side between the second pipe portion 32 and the third pipe portion. Sediment water containing a large amount of sand discharged from one or more through holes 321 or 322, 323 of the pipe member 3 falls into the gutter, travels through the gutter, is accumulated in one place, and the moisture is removed by the vibrating sieve 42. Be excluded. Moisture is filtered from the sand-rich soil water, and the accumulated sand is transported to the sand reclamation site by, for example, a soil carrier (not shown). The vibrating sieve 42 does not have to be provided.

(Overview of Pipe Member According to the Present Invention)
FIG. 2 is a diagram illustrating an outline of an example of a pipe member 3 according to an embodiment. FIG. 2A is a side view of the pipe member 3, and FIG. 2B is a cross-sectional view of the pipe member 3 in a plan view.

The pipe member 3 is connected to a pump connection portion 30 connected to a pump 2 for pumping earth and sand water, a first pipe portion 31 to which a pump connection portion 30 is connected to one end, and the other end of the first pipe portion 31. It has a second pipe portion 32. Further, the pipe member 3 may have a third pipe portion 33 connected to the other end of the second pipe portion 32. The diameter φ2 of the second pipe portion 32 is larger than the diameter φ1 of the first pipe portion 31. The diameter φ3 of the third pipe portion 33 is smaller than the diameter φ2 of the second pipe portion 32. For example, the diameter φ1 of the first pipe portion 31 is 60 mm, the diameter φ2 of the second pipe portion 32 is 150 mm, and the diameter φ3 of the third pipe portion 33 is 60 mm.

One end of the pump connection portion 30 is connected to a pump 2 (not shown) for pumping earth and sand water containing sand, and the other end is connected to one end of the first pipe portion 31. The diameter of the first pipe portion 31 is φ1. At the other end of the first pipe portion 31, there is a first connection portion 311 which is connected to the second pipe portion 32. Since the diameter φ2 of the second pipe portion 32 is larger than the diameter φ1 of the first pipe portion 31, it is preferable that the first connection portion 311 is tapered toward the second pipe portion 32 side. This is because the channel diameter of the sediment water gradually increases, so that the occurrence of irregular turbulent flow can be prevented.

The pipe length of the second pipe portion 32 is from 10 m to several tens of m. The flow velocity of earth and sand water passing through the pipe is slower than the flow velocity of the first pipe portion 31, and it is divided into a lower running water layer containing a large amount of heavy sand with a large particle size and an upper running water layer containing a large amount of light mud with a small particle size. This is because an appropriate pipe length is required to start separating and flow as a stable lower running water layer and an upper running water layer.

Therefore, usually, the second pipe portion 32 is made by connecting a plurality of long main steel pipes 341, 342, 243, 344 having the same diameter. For connecting the main steel pipes to each other, for example, steel pipe joints 351 and 352, 353 are used. Through holes 321, 322, and 323 are formed in the steel pipe joints 351 and 352, 353 to penetrate from the inner wall of the side surface of each pipe to the outer wall and to discharge the sand contained in the earth and sand water pumped from the pump. There is. In this example, all three steel pipe joints 351 and 352, 353 are provided with through holes, but only one or more through holes may be provided at appropriate positions in the second pipe, and all steel pipe joints may be provided. The fitting does not need to have a through hole. Further, through holes may be provided in the main steel pipes 341, 342, 243 and 344.

The through holes 321, 322, and 323 are provided at a position where the central axis of the pipe, that is, the plane perpendicular to the direction in which the earth and sand flow flows and the inner wall of the pipe intersect in the second pipe portion 32. It is preferable that the through holes 321, 322, and 323 have a rectangular shape when viewed in a plan view, and the short side of the rectangle is parallel to the central axis of the pipe, that is, in the direction in which sediment water flows. The through hole may have another shape.

Further, a third pipe portion 33 having a second connecting portion 331 is connected to the sediment water outflow side of the second pipe portion 32. The diameter φ3 of the third pipe portion 33 is smaller than the diameter φ2 of the second pipe portion 32. Preferably, the diameter is the same as that of the first pipe portion 31. Since the diameter φ3 of the third pipe portion 33 is smaller than the diameter φ2 of the second pipe portion 32, it is preferable that the inside of the pipe of the second connecting portion 331 is tapered from the side of the second pipe portion 32. This is to prevent sediment water from flowing back to the second pipe portion 32 side.

By connecting the third pipe portion 33 to the second pipe portion 32, the inside of the pipe of the second pipe portion 32 is filled with earth and sand water, and the flow of the earth and sand water in the second pipe portion 32 is stabilized. The efficiency of sand recovery due to sand settling is improved. Further, the earth and sand water after the sand is collected passes through the third pipe portion 33 and is sent to a landfill or a dumping site. The pipe member 3 does not have to have the third pipe portion 33.

FIG. 3 is a diagram showing an example of a steel pipe joint having a through hole. FIG. 3A is a diagram showing a state in which two main steel pipes are connected by a steel pipe joint. FIG. 3B is a front view of a steel pipe joint having a through hole. FIG. 3 (c) is a cross-sectional view taken along the line AA'shown in FIG. 3 (b).

The main steel pipes 341 and 342 each have a flange 346 around the steel pipe opening, and the flange 346 is provided with four fastening holes 347 for fastening the main steel pipe and the steel pipe joint. The steel pipe joint 351 has flanges 356 around the steel pipe openings on both sides. Each flange 356 is provided with four or more fastening holes 357. The flanges 346 of the main steel pipes 341 and 342 and the two flanges 356 of the steel pipe joint 351 are joined, and four bolts 358 are passed through the fastening holes 347 and fastened by nuts 359. The steel pipe joint 351 is provided with a through hole 321 on the side surface of the pipe in order to discharge the earth and sand water containing a large amount of sand flowing through the second pipe portion 32 to the outside of the pipe.

FIG. 3B is a front view of a steel pipe joint 351 provided with a through hole 321. The diameter of the steel pipe joint 351 is φ2. FIG. 3 (c) is a cross-sectional view taken along the line AA'shown in FIG. 3 (b). The through hole 321 is provided at a position where the pipe center axis of the steel pipe joint 351, that is, a plane perpendicular to the direction in which earth and sand flow flows, intersects the inner wall of the steel pipe joint 351 and is formed so as to penetrate from the inner wall to the outer wall. To. It is preferable that the shape of the through hole 321 is, for example, a rectangular shape when viewed in a plan view, and the short side of the rectangle is parallel to the central axis of the pipe, that is, in the direction in which sediment water flows. The through hole may have another shape.

Although a method of connecting a plurality of main steel pipes to form a second pipe portion by using a steel pipe joint 351 provided with a through hole 321 has been described, the steel pipe joint is not limited to the flange type, and other joints such as, for example, A screw-in type pipe joint may be used. Further, a through hole may be formed so as to penetrate from the inner wall to the outer wall of the short steel pipe, and the short steel pipe and the main steel pipe may be connected by, for example, a Victoria joint.

FIG. 4 is a diagram showing an example of a steel pipe joint having an obstacle plate in front of the through hole of the steel pipe joint shown in FIG.

FIG. 4A is a front view of a steel pipe joint 351 ′ having a baffle plate 361. FIG. 4B is a cross-sectional view taken along the line AA'shown in FIG. 4A. The obstruction plate 361 is a plate having a straight upper end formed by standing upright from the inner wall of the pipe toward the center of the pipe in parallel with the long side of the rectangular through hole 321 of the steel pipe joint 351'.

FIG. 4C is a cross-sectional view taken along the line BB'shown in FIG. 4A, and is a diagram illustrating the effect of the baffle plate.

The earth and sand water that has passed through the first pipe portion at the first flow velocity flows through the second pipe portion at a second flow velocity slower than the first flow velocity. This is because the diameter of the second pipe portion is larger than the diameter of the first pipe portion. The sediment water flowing through the second pipe portion at the second flow velocity begins to be divided into a running water layer containing a large amount of sand and a running water layer containing a large amount of mud. Since sand has a larger particle size and is heavier than mud, the running water layer containing a large amount of sand flows under the pipe, that is, on the above-ground side in the pipe.

When a running water layer containing a large amount of sand hits the obstruction plate 361, turbulence occurs. Since the through hole 321 is formed at the position where the sand settles, the running water containing a large amount of sand is discharged to the outside of the pipe. Since the flowing water due to the turbulent flow generated by the obstruction plate 361 is further added to the flowing water discharged from the through hole 321 to the outside of the pipe from the running water layer containing a large amount of sand, the amount of water containing sand discharged to the outside of the pipe increases. .. Therefore, the amount of sand discharged increases.

Therefore, the baffle plate 361 is formed upright from the inner wall of the pipe toward the center of the pipe on the downstream side where the earth and sand water flows in the vicinity of the through hole 321. The distance between the through hole and the baffle plate 361 is preferably 0 mm or more and 20 mm or less. The maximum height of the baffle plate 361 from the inner wall is 1/4 or less and 1/8 or more of the diameter.

(Experiment of pipe member)
The inventor conducted an experiment for examining the parameters of the pipe member according to the present invention in order to improve the sand recovery efficiency.

The items to be examined for the parameters are to appropriately set the first flow velocity when the earth and sand flow through the first pipe and the second flow velocity when the earth and sand flow through the second pipe, and to provide the second pipe. Appropriately set the position of the first through hole (first through hole), appropriately set the number of through holes provided in the second pipe part, and place a baffle plate on the downstream side where the earth and sand water of the through hole flows. It is to verify the effect when it is provided. One evaluation index for the study is the sand recovery rate from sediment water.

FIG. 5 is a diagram showing an outline of an experiment of a pipe member according to the present invention.

A water storage tank 5 that stores earth and sand water mixed with coarse sand, fine sand, clay, and water, a pump 6 that discharges earth and sand water from the water storage tank 5, and earth and sand water that is discharged from the pump 6 are passed through. An experiment was conducted by installing a pipe member 7 for recovering sand from the water on land.

The pipe member 7 has a pump connection portion 70, a first pipe portion 71, a second pipe portion 72, and a third pipe portion 73. The second pipe portion 72 can be provided with five through holes 721 to 725. In this experiment, the distance between each through hole is set to 6 m. Under each through hole, buckets 81 to 85 for receiving the earth and sand water flowing out of each through hole are installed. In addition, a bucket 86 is installed on the sediment water discharge side of the third pipe portion. By measuring the amount of sand in the earth and sand collected in each bucket 81 to 86, the sand recovery performance of the pipe member can be analyzed.

The inventor uses a pipe member 7 in which the inner diameter φ1 of the first pipe portion 71 is 60 mm, the inner diameter φ2 of the second pipe portion 72 is 150 mm, and the inner diameter φ3 of the third pipe portion 73 is 60 mm. In order to obtain a pipe member with high sand recovery efficiency, experiments were conducted with various setting parameters changed. The pipe length of the first pipe portion 71 was fixed at 1.25 m.

The side of the pipe member 7 connected to the first pipe portion 71 and the second pipe portion 72 is curved upward in a U-shape (the portion 74 shown by the dotted line in the figure). The remaining portion of the second pipe portion 72 following the curved portion is horizontal. The side of the second pipe portion 72 connected to the first pipe portion is curved upward in a U-shape in order to lengthen the pipe length of the second pipe portion 72 and to facilitate the change of the pipe length. Is. The length Lp (m) is the pipe length from the pump 6 to the first through hole 721 of the second pipe portion 72.

Further, a first current meter 91 is provided in the first pipe portion 71, a second current meter 92 is provided on the sediment water inflow side of the second pipe portion 72, and a third current meter 93 is provided on the sediment water inflow side of the third pipe portion 73. , The first flow velocity, the second flow velocity, and the third flow velocity, which are the flow velocities of each pipe portion, are measured.

The speed at which soil particles in the earth and sand water gradually settle, accumulate, and stand still in the pipe and finally block the inside of the pipe is called the limit flow velocity. Therefore, the flow velocity in the first pipe portion (φ1 = 60 mm) is equal to or higher than the limit flow velocity and is in the flow velocity range in which sand does not accumulate, and the flow velocity in the second pipe portion (φ2 = 150 mm) is determined. It is required that the flow velocity is equal to or higher than the limit flow velocity and the flow velocity range is such that sand is deposited but clay silt is not deposited.

In this experiment, three types of sediment water, first sediment water, second sediment water, and third sediment water were used.

(Examination of flow velocity in the pipe)
Appropriate in-pipe flow velocity was investigated using the first sediment water (clay + intermediate sand), which is the standard composition of dredged sediment. The second pipe portion 72 was provided with five through holes. The first through hole 721 is formed at a position where the distance from the pump 6 is 10.6 m. The distance between each through hole is 6 m. The through holes are all rectangular in a plan view of 10 mm × 50 mm. The short side of the rectangle is the length in the direction in which the earth and sand water flows in the pipe, and the long side of the rectangle is the length in the plane perpendicular to the central axis of the pipe.

For rectangles with through holes of 20 mm × 100 mm and 30 mm × 100 mm, the amount of earth and sand discharged from the through holes was too large, and clay and intermediate sand were mixed, which was an inappropriate size for sand recovery.

Table 2 is a table showing the relationship between the in-pipe flow velocities of each pipe portion of the pipe member 7 in the first earth and sand water.

When the flow velocity of the second pipe portion 71 was 0.54 m / sec, the earth and sand water could not reach the third pipe portion 73. However, the earth and sand water can be recovered even if it does not reach the third pipe portion 73. Therefore, the flow velocity of the first pipe portion 71 is 3 m / sec or more, preferably 4 m / sec. The flow velocity of the second pipe portion 72 is 0.7 m / sec or more, preferably 0.8 m / sec or more. Since the diameter of the second pipe portion 72 is larger than the diameter of the first pipe portion 71, the flow velocity of the second pipe portion 72 does not exceed the flow velocity of the first pipe portion 71.

Next, the sand recovery rate for each of the five through holes when the first earth and sand water was flowed through the pipe member 7 was measured.

FIG. 6 is a diagram showing the sand recovery rate (weight ratio) for each through hole. In FIG. 6A, the flow velocity in the second pipe portion is 0.7 m / sec, in FIG. 6B, the flow velocity in the second pipe portion is 0.8 m / sec, and in FIG. 6C, the second pipe portion is used. The flow velocity in the pipe portion is 0.9 m / sec, and the flow velocity in the second pipe portion is 1.0 m / sec in FIG. 6 (d).

When the flow velocity in the second pipe is 0.7 m / sec, the total sand recovery rate of the five through holes is 80%, and when it is 0.8 m / sec, it is 80% and 0.9 m / sec. At one time, it is 75%, and at 1.0 m / sec, it is 87%. Therefore, in the case of the first sediment water, which is the standard composition of dredged sediment, the number of through holes is more preferably 3 or more and 5 or less.

Further, in the case of the first earth and sand water, the flow velocity in the second pipe portion is preferably 0.7 m / sec or more. Therefore, the discharge pressure of the pump 2 is adjusted so that the flow velocity in the second pipe portion is 0.7 m / sec or more. More preferably, the flow velocity in the second pipe portion is 1.0 m / sec or more.

(Position of first through hole)
An appropriate position of the first through hole was examined by changing the distance from the pump 6 for discharging earth and sand water to the first through hole 721.

Table 3 shows the results of measuring the amount of earth and sand (indicated as muddy water + sand in the table) and the amount of sand discharged from the first through hole 721 when the first earth and sand water was flown. In addition, the flow velocities in the second pipe section were tested in two ways, 0.74 m / sec and around 0.90 m / sec.

As the position of the first through hole 721 (distance from the pump 6) increases from 10.6 m to 16.6 m and 22.6 m, the amount of sand discharged tends to be slightly smaller. Further, if the distance from the pump 6 to the first through hole 721 is set to 10 m or more, it is considered that the influence of the turbulent flow is small. Therefore, the position of the first through hole 721 preferably has a distance of 10 m or more from the pump 6. Further, the flow velocity in the second pipe portion is preferably 0.8 m / sec or more.

(Effect of obstacle board)
As described in FIG. 4, it is expected that the sand recovery rate will be improved by providing the baffle plate in front of the through hole. Therefore, a plate with a thickness of 6 mm, which stands up from the inner wall of the pipe and has a maximum height of 20 mm from the inner wall of the pipe, is installed at a position 10 mm downstream of the sediment water flow of the rectangular through hole of 10 mm × 50 mm in parallel with the long side of the rectangle. An experiment was conducted by setting it up. The experiment was conducted with the first through hole 721 at a position of 10.6 m from the pump 6 and the number of through holes being three.

FIG. 7 is a diagram comparing the sand recovery rate (weight ratio) for each through hole when the baffle plate is not provided and when the baffle plate is provided for the first earth and sand water. In FIG. 7A, the flow velocity in the second pipe portion is 0.85 m / sec, in FIG. 7B, the flow velocity in the second pipe portion is 0.95 m / sec, and in FIG. 7C, the second pipe portion is used. The flow velocity in the pipe portion is 1.05 m / sec.

In most cases, installing a baffle plate in front of the through hole will improve the sand recovery rate. In particular, the effect of the baffle plate in the first through hole is high.

(Examination of the characteristics of earth and sand water)
In this experiment, as shown in Table 1, in addition to the first sediment water, the second sediment water containing clay and fine sand and the third sediment water containing clay and coarse sand were used. Similar to the first sediment water, the sand recovery rate for each through hole was measured for the second sediment water and the third sediment water.

FIG. 8 is a diagram comparing the sand recovery rate (weight ratio) for each through hole when the baffle plate is not provided and when the second earth and sand water is provided. In FIG. 8A, the flow velocity in the second pipe portion is 0.85 m / sec, in FIG. 8B, the flow velocity in the second pipe portion is 1.0 m / sec, and in FIG. 8C, the second pipe portion is used. The flow velocity in the pipe portion is 1.1 m / sec.

In most cases, installing a baffle plate in front of the through hole will improve the sand recovery rate. In particular, the effect of the baffle plate in the first through hole is high. In addition, the sand recovery rate of the second sediment water tends to be lower than that of the first sediment water. This is because the sand particles are light.

FIG. 9 is a diagram comparing the sand recovery rate (weight ratio) for each through hole when the baffle plate is not provided and when the obstruction plate is provided for the third earth and sand water. In FIG. 9A, the flow velocity in the second pipe portion is 0.8 m / sec, in FIG. 9B, the flow velocity in the second pipe portion is 1.0 m / sec, and in FIG. 9C, the second pipe portion is used. The flow velocity in the pipe portion is 1.1 m / sec.

In most cases, installing a baffle plate in front of the through hole will improve the sand recovery rate. In particular, the effect of the baffle plate in the first through hole is high.

(Outline of sand recovery ship according to the present invention)
Dredging work is carried out in various places such as harbors, rivers and lakes. In addition, the dredged soil is sent to a landfill near the dredging work site, or if there is no landfill nearby, it is sent to a remote landfill. Therefore, if there is a sand recovery ship equipped with the sand recovery system according to the present invention, it can be placed next to the dredging ship or berthed near the landfill, so that it is possible to efficiently perform the process from dredging work to sand recovery. become.

FIG. 10 is a diagram showing an example of a sand recovery ship according to the present invention.

For example, the earth and sand dredged by the grab dredger is transported to the shore by the earth carrier. A sand recovery vessel 10 is berthed on the shore. The sand recovery vessel 10 includes a sand recovery system 1 having a pump 2, a pipe member 3, and a recovery device 4.

If necessary, the dredged earth and sand carried by the earth carrier is mixed with seawater or the like to become earth and sand water, which is pumped to the pipe member 3 by the pump 2. The sand recovered by the pipe member 3 is mounted on a dump truck, for example, by the recovery device 4, and is carried to a sand recycling site. On the other hand, the earth and sand water after the sand is collected is sent to the landfill. In this example, the sand recovery vessel 10 is berthed, but the sand recovery vessel 10 may be placed next to the grab dredger to perform sand recovery processing.

It will be appreciated by those skilled in the art that various changes, substitutions and modifications can be made to this without departing from the spirit and scope of the invention.

1 Sand recovery system 2, 6 Pump 3, 7 Pipe member 30, 70 Pump connection part 31, 71 First pipe part 32, 72 Second pipe part 321 to 325, 721 to 725 Through hole 361 Obstacle plate 33, 73 Third Pipe 4 Recovery device 10 Sand recovery ship

Claims (6)

A pump connection that is connected to a pump that pumps earth and sand water containing sand,
A first pipe portion having the pump connection portion arranged at one end and having a diameter of the first diameter, and a first pipe portion.
It has a second pipe portion that is connected to the other end of the first pipe portion and has a second diameter larger than the first diameter.
The second pipe portion is a pipe member characterized in that a single or a plurality of through holes are formed so as to penetrate from the inner wall to the outer wall and discharge sand contained in the earth and sand water pumped from the pump. The pipe member according to claim 1, further comprising a third pipe portion which is connected to the other end of the second pipe portion and has a third diameter smaller than the second diameter. The pipe member according to claim 1 or 2, further comprising a baffle plate arranged so as to stand up from the inner wall of the second pipe portion on the downstream side of at least one of the single or a plurality of through holes. A pump that pumps earth and sand water containing sand,
A pipe member connected to the pump and discharging sand contained in the earth and sand water pumped from the pump.
It has a recovery device for recovering sand discharged from the pipe member, and has.
The pipe member is
A pump connection portion connected to a pump that pumps earth and sand water containing sand,
A first pipe portion having the pump connection portion arranged at one end and having a diameter of the first diameter, and a first pipe portion.
It has a second pipe portion that is connected to the other end of the first pipe portion and has a second diameter larger than the first diameter.
The second pipe portion is a sand recovery system characterized in that a single or a plurality of through holes are formed so as to penetrate from the inner wall to the outer wall and discharge the sand contained in the earth and sand water pumped from the pump. The sand recovery system according to claim 4, wherein the pump is adjusted in discharge pressure so that the flow velocity of the earth and sand water flowing through the second pipe portion is 0.7 m / sec or more and 3.0 m / sec or less. A pump that pumps earth and sand water containing sand,
A pipe member connected to the pump and discharging sand contained in the earth and sand water pumped from the pump.
It has a recovery device for recovering sand discharged from the pipe member, and has.
The pipe member is
A pump connection portion connected to a pump that pumps earth and sand water containing sand,
A first pipe portion having the pump connection portion arranged at one end and having a diameter of the first diameter, and a first pipe portion.
It has a second pipe portion that is connected to the other end of the first pipe portion and has a second diameter larger than the first diameter.
The second pipe portion is a sand recovery ship characterized in that a single or a plurality of through holes are formed so as to penetrate from the inner wall to the outer wall and discharge the sand contained in the earth and sand water pumped from the pump.

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