JP2010090888A - Driving water injection nozzle and sand pumping apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving water injection nozzle and a sand pumping apparatus (jet pump) including the driving water injection nozzle capable of preventing a fall in sand pumping efficiency of sediment sand even if a dead space (place where sediment sand tends to accumulate) is formed at the bottom part of a sediment sand pit due to arrangement of a driving water pipe. <P>SOLUTION: The driving water injection nozzle 1 provided at the tip part of the driving water pipe 5 is structured to have a first bent part 12 changing downward flow into a horizontal direction; an eccentric reducer part 13 extending from the downstream end of the first bent part 12 and reduced in diameter toward the downstream side from the upstream side; a second bent part 14 extending from the downstream end of the eccentric reducer part 13 and changing horizontal flow into an upward direction; and a nozzle part 15 extending from the downstream end of the second bent part 14 and formed with a discharge port 1a opened facing a suction port 2a of a suction pipe 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sand pumping device for sanding a sand settling in a sewage treatment plant or a pumping plant and sinking to the bottom of the pond. In particular, the present invention relates to a jet pump type sand raising device.

  Bucket conveyor systems have been used frequently for sand collection from sand settling basins such as sewage treatment plants, but in recent years, odor countermeasures, simplified maintenance, and equipment cost reduction measures have been used. From the point of view, the adoption of jet pump type sand raising devices is increasing. A jet pump type sand raising device is a type of sand raising device that ejects water at a high pressure from a nozzle (driving water jet nozzle) and sucks and discharges sand using the negative pressure generated at this time. .

  Here, as a technique related to the jet pump type sand raising apparatus, for example, there is a technique described in Patent Document 1. In the sand raising device (jet pump) described in Patent Document 1, the open end of the receiving pipe is arranged so that there is no jet nozzle that jets the jet water flow in the receiving pipe that sucks in an object to be pumped up such as sand. And the opening end of the jet nozzle are arranged at a certain distance in the tube axis direction. And in Patent Document 1, “the structure of the receiving tube is simple, clogging of sand, impurities, etc. is small, and the receiving tube and the jet nozzle are arranged to face each other at a constant interval as described above. Therefore, it is possible to repair each part of the apparatus very easily. "

Japanese Patent No. 2755382

  On the other hand, in the sand pump using the jet pump system, the suction force of the sand settling in places other than the vicinity of the suction port disposed in the sand settling pit is small, and only a part of the sand settling in the sand settling pit can be removed. There is a conventional problem. Here, according to the technique described in the above-mentioned Patent Document 1, it is possible to prevent the receiving pipe from being blocked by sand, foreign substances and the like, and to easily repair each part of the apparatus. However, in the jet pump described in Patent Document 1, it is unavoidable that the driving water pipe having a large number of bends is disposed below the receiving pipe. For this reason, a dead space in which sedimentation tends to accumulate (a suction force hardly acts on the sedimentation) is formed at the bottom of the sedimentation pit due to the arrangement of the drive water pipe. That is, the jet pump described in Patent Document 1 is improved in its maintainability compared to the conventional one, but from the viewpoint of removing the sedimentation accumulated at the bottom of the sedimentation pit, It is inferior.

  The present invention has been made in view of the above circumstances, and the purpose of the present invention is to increase the sedimentation even if a dead space (a place where sedimentation tends to accumulate) is formed at the bottom of the sedimentation pit due to the arrangement of the driving water pipe. A driving water jet nozzle capable of preventing a decrease in sand efficiency and a sand raising device (jet pump) provided with the nozzle.

Means and effects for solving the problems

  As a result of intensive studies to solve the above problems, the inventors of the present invention have, from the upstream side to the downstream side, the portion of the driving water spray nozzle provided at the tip of the driving water pipe that is parallel to the bottom surface of the sand pit. By finding a reducer portion whose diameter decreases as it goes, the position (level) of the discharge outlet of the drive water pipe can be lowered while keeping the pipe pressure loss of the drive water pipe low, thereby finding that the above problem can be solved. Based on this, the present invention has been completed.

  That is, in order to solve the above-mentioned problem, the present invention is a driving water injection nozzle provided at the tip of a driving water pipe of a sand raising device that sucks sand in a solid-liquid mixed state and raises the sand, and flows downward. A first bent portion that changes the horizontal direction, a reducer portion that extends from a downstream end portion of the first bent portion, and has a diameter that decreases from the upstream side toward the downstream side, and a downstream end portion of the reducer portion A second bent portion that extends from the second bent portion that changes the flow in the horizontal direction upward, and a discharge port that extends from the downstream end of the second bent portion and opens to the suction port of the suction pipe. Provided is a drive water jet nozzle comprising a nozzle portion formed at a tip.

  According to this structure, the position (level) of the discharge port can be lowered while the pipe pressure loss of the drive water pipe is kept low by the reducer portion whose diameter decreases from the upstream side toward the downstream side. Here, by keeping the pipe pressure loss of the drive water pipe low, the momentum of the jet water flow from the drive water pipe that is ejected from the discharge port toward the suction port of the suction pipe does not drop (the momentum can be kept high). Moreover, the position (level) of the discharge port of the driving water pipe can be lowered, so that the position (level) of the suction pipe of the suction pipe can also be lowered, so that the space between the bottom surface of the sand pit and the suction port of the suction pipe can be reduced. Can be shortened. As a result, even if the drive water pipe is disposed below the suction pipe and a dead space (a place where the sedimentation tends to accumulate) is formed at the bottom of the sedimentation pit, it is possible to prevent the sand collection efficiency of the sedimentation from decreasing.

  In addition, because the suction force extends to the deeper position of the sand pit by shortening the distance between the bottom of the sand pit and the suction port of the suction pipe, even if there is a dead space at the bottom of the sand pit, You can inhale more sand.

  In the present invention, it is preferable that the reducer portion is an eccentric reducer portion whose opening center is shifted downward as it goes from the upstream side to the downstream side.

  According to this configuration, the position (level) of the discharge port of the drive water pipe can be further reduced. Therefore, the distance between the bottom surface of the sand pit and the suction port of the suction pipe can be further shortened.

  Furthermore, in this invention, it is preferable to provide the air supply nozzle which has the aperture | diaphragm | squeeze part attached to the front-end | tip part of the said nozzle part, and whose opening diameter reduces as it goes upwards.

  According to this configuration, the air jetted upward from the air supply nozzle is prevented from spreading obliquely upward, and rises with a flow that concentrates on the suction port center of the suction pipe. The sedimentation layer between and around the mouth can be easily broken, that is, it is possible to further prevent the sedimentation efficiency of the sedimentation from decreasing. In addition, by supplying air from the air supply nozzle, the settling sand is washed in the process of being sucked and transferred to the suction pipe, and the resistance in the sand pipe such as the suction pipe is reduced, so that the sand lifting efficiency is improved.

  Furthermore, in the present invention, it is preferable to further include a second reducer portion that is disposed between the second bent portion and the nozzle portion and has a diameter that decreases from the upstream side toward the downstream side.

  According to this configuration, the diameter of the driving water spray nozzle is reduced (squeezed) in two stages. Thereby, the piping pressure loss of the drive water pipe can be kept lower.

  Moreover, according to the 2nd aspect, this invention provides the sand raising apparatus provided with the drive water injection nozzle of this invention. According to this sand pumping device, even if a drive water pipe is arranged under the suction pipe and a dead space (a place where sand settling tends to accumulate) is formed at the bottom of the sand settling pit, the sand pumping efficiency of sand settling can be prevented. Can do.

It is a side view of the sand raising apparatus provided with the drive water injection nozzle which concerns on one Embodiment of this invention. FIG. 2 is an enlarged view around a driving water jet nozzle of FIG. 1. It is a BB arrow line view of FIG. 2, and AA sectional drawing. It is an enlarged side view around the drive water injection nozzle which concerns on other embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following description, a jet pump type sand pumping device is referred to as a “jet pump”.

(Configuration of jet pump)
FIG. 1 is a side view of a jet pump 10 (sand raising apparatus) provided with a drive water jet nozzle 1 according to an embodiment of the present invention. FIG. 2 is an enlarged view around the drive water jet nozzle 1 of FIG. 3 is a cross-sectional view taken along the line BB in FIG.

  As shown in FIG. 1, the jet pump 10 of the present embodiment includes a suction pipe 2 disposed in the center of the sand settling pit 3 and a drive water pipe having a discharge port 1 a that opens to face the suction port 2 a of the suction tube 2. And 5. The drive water pipe 5 is for injecting high-pressure water toward the suction port 2 a of the suction pipe 2, and the drive water injection nozzle 1 is provided at the tip thereof. The jet pump 10 also includes an air supply pipe 4, a pressure water pump (not shown), a sand collecting device (not shown), and the like.

  Here, the sand settling pit 3 is formed at the bottom of a sand settling pond provided in a sewage treatment plant or a pumping station. A sand basin is a concrete pond into which sewage that reaches a sewage treatment plant or a pump station flows first, and is provided to remove sand and impurities contained in the sewage. Sand having a specific gravity greater than that of water sinks to the bottom of the settling basin by slowly flowing sewage, and is poured into the settling pit 3 by a sand collecting device (not shown).

  The sand settling pit 3 is made of concrete, and has a trapezoidal shape with an upper opening (a shape that narrows downward) as shown in FIG. 1 in a cross-sectional view. The shape of the sand settling pit 3 is not limited to that shown in FIG. For example, it may have a rectangular shape with an open top in a cross-sectional view.

(Suction pipe)
The suction pipe 2 arranged at the center of the sand settling pit 3 sucks the sand settling 20 accumulated in the sand settling pit 3 from the suction port 2a at the tip thereof in a solid-liquid mixed state, and is connected to the suction pipe 2 ( It is for discharging the sedimentation sand 20 to the sedimentation separator (not shown) via the (not shown). The suction pipe 2 is a stainless steel pipe, and is arranged at the center of the sand settling pit 3 with its longitudinal direction aligned with the vertical direction.

(Drive water pipe)
As shown in FIG. 2, the drive water pipe 5 is for injecting pressure water toward the suction port 2 a of the suction pipe 2, and the pressure water flows through the inside thereof. The drive water pipe 5 includes a straight pipe 11 and a drive water injection nozzle 1 connected to the straight pipe 11 by welding. The straight pipe 11 and the drive water spray nozzle 1 are both made of stainless steel. The drive water pipe 5 is connected to a pressure water pump (not shown) on the upstream side. The pressure water pump (not shown) is one of the devices constituting the jet pump 10.

(Drive water injection nozzle)
The straight pipe 11 is piped with its longitudinal direction aligned with the vertical direction. And the drive water injection nozzle 1 welded and attached to the downstream end part of the said straight pipe 11 is the 1st bending part 12 which changes the flow of a downward direction into a horizontal direction, and the downstream end of the 1st bending part 12 An eccentric reducer portion 13 (reducer portion) that extends from the portion and decreases in diameter from the upstream side toward the downstream side, and extends from the downstream end portion of the eccentric reducer portion 13 to change the flow in the horizontal direction upward. A second bent portion 14 and a nozzle portion 15 that extends from the downstream end portion of the second bent portion 14 and forms a discharge port 1a that opens at the front end facing the suction port 2a of the suction pipe 2 are provided. .

  Here, the straight pipe 11, the first bent portion 12, the eccentric reducer portion 13, the second bent portion 14, and the nozzle portion 15 are all connected (welded connected) to each other by welding (butt welding). In FIG. 2, the weld line is indicated by w. These members may be connected to each other via a flange (flange connection), or may be screwed (screw connection) (the same applies to other embodiments described later).

(First bend)
The first bent portion 12 is an elbow member (90 ° elbow) that changes the vertically downward flow to the horizontal direction, and is welded to the downstream end of the straight pipe 11. The pipe diameter of the straight pipe 11 and the pipe diameter of the first bent portion 12 are equal. The straight pipe 11 is not limited to pipes whose longitudinal direction is aligned with the vertical direction, and includes pipes that are piped at an angle such as obliquely downward. In this case, since the first bent portion 12 is a member (tube) that changes the downward flow to the horizontal direction, the first bent portion 12 is not limited to a 90 ° elbow, but a 45 ° elbow or the like. There is also.

(Eccentric reducer)
The eccentric reducer portion 13 is a member whose longitudinal direction is arranged in parallel with the bottom surface of the sand settling pit 3, and is welded to the downstream end portion of the first bent portion 12. Moreover, the eccentric reducer part 13 is reducing the pipe diameter of the drive water pipe 5 from the pipe diameter of the 1st bending part 12 to the pipe diameter of the 2nd bending part 14 mentioned later. Here, in the present embodiment, in the side view of the eccentric reducer portion 13, the inclination angle α between the busbar 13b on the upper side of the truncated cone and the horizontal line is 30 degrees. The inclination angle α is preferably 20 degrees or more and 60 degrees or less. If the inclination angle α is too small, the eccentric reducer 13 must be lengthened in order to lower the level of the pipe, so the bottom surface of the sand pit 3 needs to be widened. On the other hand, if the inclination angle α is too large, This is because the pipe pressure loss of the drive water pipe 5 becomes large.

  Moreover, the cross-sectional shape of the eccentric reducer part 13 is circular, and the opening center is shifted downward as it goes from the upstream side to the downstream side. Here, in FIG. 2, a line connecting the opening centers of the eccentric reducer portions 13 is shown as an opening center line β. The opening center line β is a downward-sloping line. Further, in the present embodiment, in the side view of the eccentric reducer portion 13, the first bent portion 12 is maintained so that the lower busbar 13 a of the truncated cone is horizontal (parallel to the bottom surface of the sand settling pit 3). The tube diameter is reduced from the tube diameter to the tube diameter of the second bent portion 14 described later.

  Note that the opening center line β may be horizontal. That is, it may be a concentric reducer having the same height at the opening center from the upstream side toward the downstream side. Moreover, the cross-sectional shape of the eccentric reducer portion 13 may be an ellipse or the like (the same applies to other embodiments described later).

  Further, as shown in FIG. 3A as viewed from the direction of arrows BB in FIG. 2, the bus bars 13c and 13d on both sides of the truncated cone in the plan view of the eccentric reducer portion 13 are the eccentric reducer portion 13. (The same applies to other embodiments described later).

(Second bend)
The second bent portion 14 is an elbow member (90 ° elbow) that changes the flow in the horizontal direction into a vertically upward flow, and is welded to the downstream end of the eccentric reducer portion 13. The tube diameter of the second bent portion 14 is smaller than the tube diameter of the first bent portion 12.

(Nozzle part)
The nozzle portion 15 is a cylindrical member having the same diameter as the tube diameter of the second bent portion 14, and is welded to the downstream end portion of the second bent portion 14. Pressure water is jetted from the discharge port 1 a at the tip of the nozzle portion 15 toward the suction port 2 a of the suction pipe 2. In addition, the nozzle part 15 and the 2nd bending part 14 can also be integrally molded by the bending process of a pipe | tube.

  An air supply nozzle 6 is attached to the tip of the nozzle portion 15 by screwing or welding. The air supply nozzle 6 has a cylindrical portion 6a and a throttle portion 6b. The inner diameter of the cylindrical portion 6a is larger than the outer diameter of the nozzle portion 15, and the aperture diameter of the throttle portion 6b is reduced as it goes upward. Further, the upper end of the throttle portion 6b is located above the upper end of the discharge port 1a. The downstream end of the air supply pipe 4 is connected to the side surface of the cylindrical portion 6a. An air supply device (air compressor) (not shown) is connected to the air supply pipe 4 on the upstream side. The air supply nozzle 6 is made of stainless steel. Further, the outer diameter of the air supply nozzle 6 is smaller than the inner diameter of the suction port 2 a of the suction pipe 2. The air supply pipe 4 is piped along the drive water pipe 5. In addition, the air supply apparatus may not be connected to the air supply pipe 4 and the upstream end of the air supply pipe 4 may be open to the atmosphere.

(Jet pump operation)
Next, the operation of the jet pump 10 will be described.

  A pressure water pump (not shown) of the jet pump 1 is activated, pressure water is supplied to the drive water pipe 5, and pressure water is injected from the discharge port 1 a toward the suction port 2 a of the suction tube 2. The jetted pressure water is sucked into the suction pipe 2 from the suction port 2 a together with the sand settling 20 in the sand settling pit 3. In this manner, the sand set 20 sucked into the suction pipe 2 is discharged to a sand set separator (not shown) via a sand settling pipe (not shown) connected to the suction pipe 2.

  Here, pressure water is jetted from the discharge port 1a of the drive water tube 5 toward the suction port 2a of the suction tube 2, and an air supply device (not shown) is activated to suck the suction tube 2 from the air supply nozzle 6. Air is supplied toward the mouth 2a. By supplying air from the air supply nozzle 6, the layer of the sedimentation sand 20 between the discharge port 1a and the suction port 2a and in the vicinity thereof is easily broken, which helps sanding in the initial stage of startup. The supply of air from the air supply nozzle 6 may be performed only at the initial stage of activation of the pressure water pump (not shown) or continuously during the operation of the pressure water pump (not shown). As shown in FIG. 3B, the tip of the air supply nozzle 6 is narrowed (throttle portion 6b), so that the air jetted upward from the air supply nozzle 6 is suppressed from spreading obliquely upward, Since it rises with a flow that concentrates at the center of the suction port 2a of the suction pipe 2, the layer of the sand settling 20 between and around the discharge port 1a and the suction port 2a can be easily broken, that is, the sanding efficiency of the sand settling 20 is reduced. Can be prevented.

  In addition, by supplying air from the air supply nozzle 6 to the suction pipe 2, the sand settling 20 sucked by the suction pipe 2 and transferred through the sand settling transfer pipe is washed. In addition, there is an effect that the pipe internal resistance in the suction pipe 2 and the sand settling transfer pipe is reduced and the sand pumping efficiency is improved.

  Further, by disposing the driving water pipe 5 below the suction pipe 2 so as to be the discharge outlet 1a that opens opposite to the suction opening 2a of the suction pipe 2, the bottom of the sedimentation pit (such as below the driving water pipe 5). ), A dead space (a place where sedimentation tends to accumulate) is formed. However, according to the jet pump 10 of the present embodiment, the position (level) of the discharge port 1a is maintained while keeping the pipe pressure loss of the drive water pipe 5 low by the eccentric reducer portion 13 whose diameter is reduced from the upstream side toward the downstream side. Can be lowered. Here, by keeping the pipe pressure loss of the drive water pipe 5 low, the momentum of the jet water flow from the drive water pipe 5 ejected from the discharge port 1a toward the suction port 2a of the suction pipe 2 does not drop (keep the momentum high). Can do). In addition, since the position (level) of the discharge port 1a of the drive water pipe 5 can be lowered, the position (level) of the suction port 2a of the suction pipe 2 can also be lowered, whereby the bottom surface of the sand settling pit 3 and the suction pipe 2 can be reduced. The distance from the suction port 2a can be shortened. Thus, even if the drive water pipe 5 is disposed below the suction pipe 2 and a dead space (a place where the sand is easily collected) is formed at the bottom of the sand settling pit 3, a decrease in the sand pumping efficiency of the sand set 20 is prevented. Can do.

  In addition, since the suction force extends to a deeper position of the sand pit 3 by shortening the distance between the bottom surface of the sand pit 3 and the suction port 2a of the suction pipe 2, there is a dead space at the bottom of the sand pit 3 Even if it is not, it is possible to suck in a larger amount of the settling sand 20 (the remaining amount of the settling sand 20 after the jet pump 1 is operated can be reduced).

  In the present embodiment, in the side view of the eccentric reducer 13, the diameter is reduced so that the lower generatrix 13a of the truncated cone is horizontal, so the position (level) of the discharge port 1a of the drive water pipe 5 Can be lowered.

(Another embodiment of the driving water jet nozzle)
FIG. 4 is a side view around the drive water jet nozzle 21 according to another embodiment. FIG. 4 is a diagram corresponding to FIG. 2 of the embodiment. In the following description, differences from the above-described drive water injection nozzle 1 will be mainly described. The same members as those constituting the jet pump 10 are denoted by the same reference numerals.

(Eccentric reducer)
The difference between the eccentric reducer portion 23 (first reducer portion) of the present embodiment and the eccentric reducer portion 13 is the tube diameter and the tube length of the downstream end portion. The eccentric reducer portion 23 of the present embodiment has a tube diameter at the downstream end that is larger than that of the eccentric reducer portion 13, and as a result, the tube length is shortened. The inclination angle α is set to 30 degrees as in the case of the eccentric reducer 13. Further, similarly to the eccentric reducer portion 13, the inclination angle α is preferably not less than 20 degrees and not more than 60 degrees. If the inclination angle α is too small, the eccentric reducer 23 must be lengthened to lower the level of the tube, so the bottom surface of the sand pit 3 needs to be widened. On the other hand, if the inclination angle α is too large, This is because the pipe pressure loss of the drive water pipe 25 becomes large.

  In addition, according to this embodiment, since the tube length of the eccentric reducer part 23 arrange | positioned in parallel with respect to the bottom face of the sand settling pit 3 becomes shorter than the tube length of the eccentric reducer part 13 as mentioned above, it is more compact in planar view. The driving water jet nozzle 21 becomes a new one.

(Second bend)
The difference between the second bent portion 24 of the present embodiment and the second bent portion 14 is the pipe diameter. The tube diameter of the second bent portion 24 of the present embodiment is smaller than the tube diameter of the first bent portion 12 and larger than the tube diameter of the second bent portion 14.

(Second reducer part)
The drive water jet nozzle 21 of the present embodiment further includes a second reducer portion 22. The second reducer portion 22 is a member whose axial center direction is arranged in the vertical direction, and is welded to the downstream end portion of the second bent portion 24. Moreover, the 2nd reducer part 22 is reducing the pipe diameter of a drive water injection nozzle from the pipe diameter of the 2nd bending part 24 to the pipe diameter of the nozzle part 25 mentioned later. Here, the 2nd reducer part 22 is a concentric reducer part (concentric reducer). In the side view of the second reducer portion 22, the inclination angle γ between the frusto-conical bus bar 22a (22b) and the axial direction (vertical direction) is 25 degrees. The inclination angle γ is preferably 20 degrees or more and 40 degrees or less. This is because if the inclination angle γ is too small, the position of the nozzle portion 25 becomes high, and if the inclination angle γ is too large, the piping pressure loss of the drive water pipe 25 becomes large.

  The second reducer unit 22 may be an eccentric reducer (second eccentric reducer unit) instead of the concentric reducer. In this case, it is preferable that the bus 22b on the side located on the outer side of the driving water jet nozzle 21 is aligned with the vertical direction, and the bus 22a on the side located on the inner side is inclined. The inclination angle γ with respect to the vertical direction of the bus 22a on the inner side is preferably 25 degrees or more and 55 degrees or less. By these, the flow of the water of a 2nd reducer part becomes smoother, and it can suppress piping pressure loss lower.

(Nozzle part)
The nozzle portion 25 is a nozzle that extends from the downstream end portion of the second bent portion 24 via the second reducer portion 22 and forms a discharge port 1a that opens opposite to the suction port 2a of the suction pipe 2 at the tip. Part. The nozzle portion 25 is a cylindrical member having the same diameter as the pipe diameter of the downstream end portion of the second reducer portion 22, and is welded to the downstream end portion of the second reducer portion 22. In addition, the nozzle part 25 and the 2nd reducer part 22 can also be integrally molded by a drawing process. Further, a structure in which air can be supplied by attaching the air supply nozzle 6 as shown in FIG.

(Experimental result)
A drive water injection nozzle 21 according to the present embodiment and a drive water injection nozzle according to a comparative example were prototyped and a performance comparison test was performed.

  The drive water injection nozzle 21 is, in order from the upstream side, a 150A straight pipe 11 (vertical pipe), a first bent portion 12 of a 150A / 90 ° elbow, and a first eccentric reducer portion 23, 80A / 90 ° elbow of 150A-80A. The second bent portion 24, the 80A-36 mm second concentric reducer portion 22, and the nozzle portion 25 having a diameter of 36 mm were used.

  On the other hand, the driving water injection nozzle according to the comparative example has a 150A straight pipe (vertical pipe), a 150A / 90 ° elbow, a 150A straight pipe (horizontally arranged short pipe), 150A / 90 ° in order from the upstream side. The nozzle was composed of an elbow, a 150A-36 mm concentric reducer, and a nozzle part having a diameter of 36 mm.

  And the pressure loss of the above-mentioned two types of drive water jet nozzles was measured. As a result, it has been found that the pressure loss can be kept sufficiently low according to the drive water jet nozzle 21. In addition, according to the drive water injection nozzle 21 of this embodiment, the level of the discharge port 1a can be made at least 100 mm lower than the drive water injection nozzle according to the comparative example.

  That is, by reducing (squeezing) the diameter of the drive water jet nozzle 21 in two stages as in the present embodiment, the pipe pressure loss of the drive water pipe can be kept sufficiently low while the level of the discharge port 1a is lowered. it can.

  Although the reduction of the diameter of the drive water injection nozzle in three stages or more (squeezing) was also considered, the pipe pressure loss is greatly reduced as compared to the case of reducing (squeezing) in two stages as in this embodiment. Was not recognized. On the other hand, as the number of diameters is increased, the level of the discharge port 1a tends to gradually increase. That is, in consideration of lowering the level of the discharge port 1a, when reducing the diameter in a plurality of stages, it is preferable to reduce (squeeze) the diameter of the drive water spray nozzle in two stages.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

  Of the driving water jet nozzle provided at the tip of the driving water pipe, the portion parallel to the bottom surface of the sedimentation pit is a reducer part whose diameter decreases from the upstream side toward the downstream side, thereby piping the driving water pipe The position (level) of the discharge port of the drive water pipe can be lowered while keeping the pressure loss low, that is, the present invention also includes a drive water jet nozzle in which the diameter is reduced in a plurality of stages of three or more stages.

1: Drive water jet nozzle 2: Suction pipe 2a: Suction port 3: Sand settling pit 5: Drive water pipe 5a: Discharge port 6: Air supply nozzle 10: Jet pump (sand raising device)
12: 1st bending part 13: Eccentric reducer part (reducer part)
14: Second bent portion 15: Nozzle portion

Claims (5)

A driving water jet nozzle provided at the tip of a driving water pipe of a sand raising device for sucking sand in a solid-liquid mixed state and sanding it,
A first bend that changes the downward flow to the horizontal direction;
A reducer portion extending from the downstream end of the first bent portion and having a diameter that decreases from the upstream side toward the downstream side;
A second bent portion extending from the downstream end of the reducer portion and changing the flow in the horizontal direction upward;
A nozzle portion extending from the downstream end of the second bent portion and forming a discharge port at the tip that opens opposite the suction port of the suction pipe;
A drive water spray nozzle comprising:   2. The drive water jet nozzle according to claim 1, wherein the reducer portion is an eccentric reducer portion whose opening center is shifted downward from the upstream side toward the downstream side.   3. The drive water jet nozzle according to claim 1, further comprising an air supply nozzle that is attached to a tip portion of the nozzle portion and has a throttle portion whose opening diameter is reduced in the upward direction.   4. The apparatus according to claim 1, further comprising a second reducer portion disposed between the second bent portion and the nozzle portion and having a diameter that decreases from the upstream side toward the downstream side. The drive water jet nozzle described.   A sand raising device provided with the drive water injection nozzle according to claim 1.

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