JP2005337203A - Drain pump system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a column type submersible pump which can be operated without sucking air through a suction port even if the minimum water level is reduced to a level lower than the conventional level so as to reduce a residual water quantity in a suction sump to increase the proportion of water retentivity in comparison with the residual water quantity. <P>SOLUTION: A suction bellmouth 16 of a vertical shaft mixed flow pump P is opened to the inside of a suction casing 21 having a closed structure. The height H6 of the ceiling 21a in the casing is set at a position sufficiently higher than the height H7 of a suction port 21d opened to a suction sump 19. An air discharge means 22 equipped with an exhaust pipe 22a, an exhaust valve 22b, an exhaust pump 22c or the like is connected to an air discharge port 21e provided in the ceiling 21a in the suction casing 21. By so doing, the pump P can be operated without sucking air even if the lowest water level of the suction sump 19 is reduced to LWL2 corresponding to 0.5D which is about a height H7 of a suction port 21d. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a drainage pump system that drains water that has flowed into a suction water tank, and more particularly, to a drainage pump system that enables a stable drainage operation at a water level lower than a conventional minimum water level.

  Conventionally, there is a drain pump pump system shown in FIG. 7 that drains water flowing into a suction water tank. This drainage pump system includes a casing 2b that rotatably accommodates an impeller 2a, a pumping pipe 2c that is connected in communication with the upper end of the casing 2b, and a suction provided at the lower end of the casing 2b. A pump 2 having a port 2d is provided, and an eddy current preventing wall 4 having a lower end extending below the lowest water level LWL is suspended from a housing 5 provided above the suction water tank 1 on the upstream side of the pump 2, and the vortex The upper end 6a is located between the highest water level HWL and the lowest water level LWL, and the lower end 6b is located below the lowest water level LWL, with a predetermined facing interval α on the upstream side of the prevention wall 4. The auxiliary wall 6 is installed in a transverse manner (for example, Patent Document 1).

  In the drainage pump system configured as described above, for example, when the water level is higher than the upper end 6a of the auxiliary wall 6, when the pump 2 is operated, a part of the flowing water sucked by the pump 2 passes over the vortex prevention auxiliary wall 6. Since the water flows down along the upstream surface 4a of the vortex-preventing wall 4, a dead water area due to the stagnation of the flowing water does not occur on the upstream side of the vortex-preventing wall 4, and the generation of vortex due to the dead water area can be prevented. .

  Moreover, since a part of the flowing water that has passed under the vortex prevention wall 4 flows between the pump 2 and the end side wall 1a of the suction water tank 1, no dead water area is generated even during this period, and the generation of the vortex can be prevented. it can. Therefore, the pump 2 sucks air by the vortex and does not cause vibration and noise, and the pump 2 can be efficiently operated to perform drainage.

JP-A-5-321897

  However, in the conventional drainage pump system, the depth (height) H2 from the bottom 1a of the suction water tank 1 to the lowest water level LWL is limited to about twice (2D) or more than the diameter D of the pump 2, and is in operation. When the water level is lower than the minimum water level LWL, air-mixed water is sucked in due to the generation of the air suction vortex, and there is a risk that severe vibration and loud noise may occur, causing malfunction of the pump operation and damaging peripheral equipment. For this reason, when the water level of the suction water tank 1 falls to the lowest water level LWL, the water level LWL is detected by a water level detection means (not shown), and the operation of stopping the pump 2 is controlled. The distance H4 from the bottom 1a of the suction water tank 1 to the suction port 2d is set to the same size as the diameter D of the pump 2.

  However, when the depth H2 from the bottom 1a of the suction water tank 1 to the lowest water level LWL is limited to 2D or more, compared to the depth H1 from the highest water level HWL to the bottom 1a of the suction water tank 1, from the lowest water level LWL. Since the depth H2 to the bottom 1a is considerably large, the water level difference H3 between the highest water level HWL and the lowest water level LWL is small, and there is a problem that the ratio of the remaining water amount is larger than the water retention amount in the suction water tank 1.

  The present invention solves such a problem, and the object of the present invention is to be able to operate a pump without sucking air even if the minimum water level is lowered to a level lower than conventional, It is an object of the present invention to provide a drainage pump system that can reduce the amount of remaining water and reduce the proportion of the remaining water amount as compared with the water retention amount.

  In order to achieve the above object, the drainage pump system according to the present invention has a suction port of a drainage pump that opens into a suction casing having a closed structure provided with a suction port that opens to a suction water tank. The air outlet is set at a position higher than the upper end of the water inlet, and an air outlet is provided at an upper position of the inlet casing, and the air outlet is connected to an air outlet. is there.

With such a configuration, if the water level of the suction water tank is lowered below the ceiling level of the suction casing due to the operation of the drainage pump, the air discharge force of the air discharge means is adjusted to the upper part in the suction casing through the air discharge port. To act on. As the water level in the suction water tank decreases from the ceiling level of the suction casing to near the upper end of the water suction port, the water level in the suction casing also tends to decrease in the same manner as the water level in the suction water tank. However, since the air discharge force of the air discharge means is acting on the upper part in the suction casing, the water level drop in the suction casing is suppressed by this air discharge force. For this reason, in the inside of a suction casing, a negative pressure part will be formed in the upper level of a water surface, and the water level in a suction casing is hold | maintained in a position higher than the water level of a suction water tank. Therefore, the drainage pump can be operated without sucking air.
On the other hand, even if air is sucked into the suction casing from the water suction port because the water level of the suction water tank is lowered near the upper end of the water suction port in the suction casing, the sucked air (bubbles) Since it raises toward the upper end of a suction casing and is discharged | emitted by an air discharge means, it can suppress sucking into a drainage pump.

  In this invention, it is preferable to equip the said suction casing with a pre-swirl flow provision means.

  By doing in this way, the water sucked into the suction casing is sucked into the drainage pump after pre-turning. For this reason, even if air (bubbles) is mixed in the pre-swirl flow, it is possible to earn time for raising the bubbles toward the upper end of the casing during the pre-swirl. Air can be prevented from being sucked into the drainage pump.

  According to the present invention, since the pump can be operated without sucking air even if the minimum water level is lowered to a level lower than the conventional level, the remaining water amount in the suction water tank is reduced, and the remaining water amount is compared with the retained water amount. The ratio of the amount of water can be reduced.

1 is a side view showing an embodiment of the present invention with a partial cross section, and FIG. 2 is a view taken along the line AA of FIG.
1 and 2, in the embodiment of the drainage pump system according to the present invention, a vertical shaft diagonal flow pump is used as the drainage pump P. This vertical shaft mixed flow pump P includes a vertical main shaft 11 rotatably supported by a plurality of underwater bearings 10, an impeller 12 fixed to a lower end portion of the main shaft 11, and a discharge housing the impeller 12 rotatably. A bowl 13, a pumping pipe 14 that is connected to the upper side of the discharge bowl 13 and accommodates the main shaft 11, is connected to the upper side of the pumping pipe 14, and passes through the main shaft 11 in a liquid-tight manner so as to be freely rotatable. And a discharge bell tube 16 is provided downwardly in communication with the discharge bowl 13, and a discharge valve 17 and a drain pipe 18 are connected downstream of the discharge curve tube 15. And it installs in the state which penetrated the pump installation floor 20 corresponded to the ceiling of the suction water tank 19, and was suspended on this pump installation floor 20.

  The suction bell mouth 16 of the vertical shaft diagonal flow pump P is opened inside the suction casing 21 having a sealed structure. The suction casing 21 has a cylindrical shape including a ceiling 21a, a bottom 21b, and a peripheral wall 21c. The suction casing 21 is watertight by canning or the like, and is installed on the bottom 19a of the suction water tank 19 so as not to move. The suction bell mouth 16 is removably inserted into the inside of the suction casing 21 and assembled in a state of penetrating the central portion of 21a in a watertight manner. In this assembled state, the distance H5 from the bottom 21b of the suction casing 21 to the suction bell mouth 16 is set to the same size as the diameter D of the vertical shaft diagonal flow pump P. The diameter D1 of the suction casing 21 is set to 3 to 5 times the diameter D (4D in this embodiment), and its height H9 is set to about 2.5 times the diameter D. is there.

  On the other hand, a water inlet 21 d that opens to the suction water tank 19 extends upstream from the suction water tank 19 at the center of the semicircular portion directed to the upstream side of the suction water tank 19 on the peripheral wall 21 c of the suction casing 21. The height H7 of the water inlet 21d is set to about 0.5D.

  On the other hand, an air discharge port 21e is provided on one side of the ceiling 21a in the suction casing 21, and the air discharge port 21e is connected to an air discharge means 22 including an exhaust pipe 22a, an exhaust valve 22b, an exhaust pump 22c, and the like. .

  In the above configuration, when the water level of the suction water tank 19 is above the ceiling 21a of the suction casing 21, the vertical shaft diagonal flow pump P is closed with the exhaust valve 22b of the air discharge means 22 closed and the operation of the exhaust pump 22c stopped. Is made. By operating the vertical shaft diagonal flow pump P, the water in the suction water tank 19 flows into the suction casing 21 through the water inlet 21d, is sucked into the suction bell mouth 16, and is discharged from the discharge bowl 13 to the pumping pipe 14. Then, the water is raised through the pumping pipe 14 and drained through the discharge curved pipe 15, the discharge valve 17, and the drain pipe 18.

  If the water level in the suction tank 19 drops to a level LWL1 lower than the ceiling 21a of the suction casing 21 due to continued operation of the vertical shaft diagonal flow pump P, the water level LWL1 is detected by a water level detection means (not shown). Based on the above, the air discharge force of the air discharge means 22 is applied to the upper part in the suction casing 21. That is, the exhaust valve 22b of the air discharge means 22 is opened and the exhaust pump 22c is operated. As an example, the depth (height) H6 to LWL1 is set to about twice (2D) the diameter D of the pump.

  By further continuing the operation of the vertical shaft mixed flow pump P, the water level in the suction water tank 19 is lowered from the level LWL1 to the vicinity of the level LWL2 at the upper end of the water inlet 21d, so that the water level in the suction casing 21 is also lowered to LWL2. To do. However, since the air discharge force of the air discharge means 22 is acting on the upper part in the suction casing 21, the water level fall in the suction casing 21 is suppressed by this air discharge force. For this reason, in the suction casing 21, the negative pressure portion 23 is formed above the water surface, and the water level WL in the suction casing 21 is held at a higher position than the water level LWL 2 of the suction water tank 19. Therefore, the vertical shaft diagonal flow pump P can be operated without sucking air until the water level in the suction water tank 19 is lowered to around LWL2.

  As described above, even if air is sucked into the suction casing 21 from the water suction port 21d because the water level of the suction water tank 19 is lowered to near LWL2, the sucked air (bubbles) is caused by its own buoyancy. Since it is discharged by the air discharge means 22 after rising to the negative pressure part 23, it can be suppressed from being sucked into the vertical shaft diagonal flow pump P.

  If the water level in the suction water tank 19 drops to near LWL2, the water level LWL2 is detected by a water level detection means (not shown), and the operation of the vertical shaft diagonal flow pump P is stopped based on this water level detection.

  That is, according to the present invention, even if the minimum water level of the suction water tank 19 is lowered to LWL2 corresponding to 0.5D which is the height H7 of the water suction port 21d, the vertical shaft mixed flow pump P is operated without sucking air. Since the depth H7 from the lowest water level LWL2 to the bottom 19a is considerably smaller than the depth H1 from the highest water level HWL to the bottom 19a of the suction water tank 19, the highest water level HWL and the lowest water level The water level difference H8 with the LWL2 is much larger than the water level difference H3 of the conventional drainage pump system (see FIG. 7), and the ratio of the remaining water amount is drastically reduced compared to the water retention amount of the suction water tank 19. Can do.

  In the present invention, the suction casing 21 having a sealed structure is preferably provided with a pre-swirl flow imparting means. That is, as shown in FIG. 3, the one side eccentric position of the semicircular portion directed to the upstream side of the suction water tank 19 in the peripheral wall 21 c of the suction casing 21 is the same as the rotation direction R of the impeller 12 inside the peripheral wall 21 c. The pre-swirl flow imparting means 24 is configured by providing the water suction port 21d in the vicinity of the tangent line of the peripheral wall 21c with directivity that can generate the pre-swirl flow S1 in the direction.

  Thus, by providing the pre-swirl flow imparting means 24, the water sucked into the suction casing 21 is pre-swirl S1 in the same direction as the rotation direction R of the impeller 12, and then the suction bell mouth 16 (see FIG. 1). ) Will be sucked into. For this reason, even if air (bubbles) is mixed in the pre-swirling flow S1, it is possible to earn time for raising the bubbles to the negative pressure portion 23 (see FIG. 1) during the pre-turning. It is possible to further increase the separation capability and further suppress air from being sucked into the vertical shaft mixed flow pump P.

  As shown in FIG. 4, the other side eccentric position of the semicircular portion of the peripheral wall 21 c of the suction casing 21 that faces the upstream side of the suction water tank 19 is positioned opposite to the rotational direction R of the impeller 12 inside the peripheral wall 21 c. The pre-swirl flow imparting means 24 may be configured by providing the water suction port 21d in the vicinity of the tangent line of the peripheral wall 21c with directivity capable of generating the pre-swirl flow S2.

  Even in such a pre-swirl flow applying means 24, the water sucked into the suction casing 21 pre-swives S2 in the direction opposite to the rotation direction R of the impeller 12 and then the suction bell mouth 16 (see FIG. 1). Therefore, even if air (bubbles) is mixed in the pre-swirling flow S2, it is possible to earn time for raising the bubbles to the negative pressure portion 23 (see FIG. 1) while pre-turning. Therefore, it is possible to further suppress the air from being sucked into the vertical shaft diagonal flow pump P by increasing the air separation capability.

  However, in the pre-swirl flow applying means 24 shown in FIG. 3, there is a concern about the lowering of the head of the vertical-shaft mixed flow pump P, and in the pre-swirling flow applying means 24 shown in FIG. Therefore, it is necessary to use a pump designed in consideration of these points.

  In the above embodiment, the vertical shaft diagonal flow pump is used as the drainage pump, but it goes without saying that a vertical shaft pump, a horizontal pump, or other types of pumps can be applied.

  Moreover, it may be an air discharge means 22 having a structure using an air exhaust instead of the exhaust pump 22c. Further, as shown by a two-dot chain line in FIG. 1, the exhaust gas connecting the air discharge port 21 e provided on one side of the ceiling 21 a in the suction casing 21 and the inside of the inner peripheral side curvature that is the negative pressure portion of the discharge curved pipe 15. The air discharge means 22 may be constituted by the pipe 22d and the exhaust valve 22e interposed in the exhaust pipe 22d.

  Furthermore, instead of the pre-swirl flow applying means 24 shown in FIG. 3, the pre-swirl flow applying means 24 having the structure shown in FIG. 5 may be adopted. The pre-swirl flow imparting means 24 forms a plurality of slits 21f at appropriate intervals in the circumferential direction on the peripheral wall 21c of the suction casing 21 instead of the water inlet 21d described in FIG. In the structure, the guide vane 21g is attached with directivity capable of generating a pre-swirl flow S1 in the same direction as the rotation direction R of the impeller 12 inside the peripheral wall 21c. The slit 21f is formed so as to open only in the range of about 0.5D (D is the diameter of the pump P) from the lower end of the suction casing 21.

  Further, instead of the pre-swirl flow applying means 24 shown in FIG. 4, the pre-swirl flow applying means 24 having the structure shown in FIG. 6 may be adopted. This pre-swirl flow applying means 24 forms a plurality of slits 21f at appropriate intervals in the circumferential direction on the peripheral wall 21c of the suction casing 21 instead of the water inlet 21d described in FIG. Has a directivity capable of generating a pre-swirl flow S2 in the direction opposite to the rotation direction R of the impeller 12 inside the peripheral wall 21c, and has a structure in which the guide vane 21g is attached. In this case as well, the slit 21f is formed so as to open only from the lower end of the suction casing 21 within a range of about 0.5D (D is the diameter of the pump P).

It is a side view which shows embodiment of this invention in a partial cross section. It is an AA arrow line view of FIG. It is a top view which shows 1st Embodiment of a pre-swirl flow provision means in a cross section. It is a top view which shows 2nd Embodiment of a pre-swirl flow provision means in a cross section. It is a top view which shows the modification of 1st Embodiment of a pre-swirl flow provision means in a cross section. It is a top view which shows the modification of 2nd Embodiment of a pre-swirl flow provision means in a cross section. It is explanatory drawing of a prior art example.

Explanation of symbols

16 Suction bell mouth (suction port of drainage pump)
DESCRIPTION OF SYMBOLS 19 Suction water tank 21 Suction casing of airtight structure 21a Ceiling of suction casing 21d Water inlet 21e Air outlet 24 Pre-swirl flow grant means P Vertical shaft diagonal flow pump (drainage pump)

Claims (2)

  The suction port of the drain pump opens in a suction casing having a sealed structure provided with a suction port that opens to the suction water tank, and the ceiling of the suction casing is set higher than the upper end of the suction port. A drainage pump system, wherein an air discharge port is provided at an upper position of the suction casing, and the air discharge port is connected to an air discharge means. The drainage pump system according to claim 1,
A drainage pump system characterized in that the suction casing is provided with a pre-swirl flow imparting means.

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