JP2012172655A - Circulation pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circulation pump of an erection type, which can reduce facility installation and construction costs, while solving the problem that a water replacing phenomenon is caused by the erection type.SOLUTION: In the circulation pump, an impeller 39 disposed in a pump casing 32 is rotated with the rotation of a rotating shaft 36 to suck hot water from a sucking part 33 of the pump casing 32 and to discharge it through an ejection part 34, while the cooling water in a motor casing 10 is circulated while being cooled with a circulation cooling mechanism 42. The connecting pipe 43 of the circulation cooling mechanism 42 is arranged with a pump 47 for sucking the cooling water in the motor casing 10 for circulation supply.

Description

  The present invention relates to a circulation pump for circulatingly supplying hot water to a boiler in a thermal power generation facility or a nuclear power generation facility.

  This type of circulation pump is provided with a pump casing at the top and a motor casing at the bottom. These casings are penetrated by a single rotating shaft, and an impeller is disposed at the upper end located in the pump casing. And a circulating pump draws in hot water from the suction part of a pump casing, and discharges it from a discharge part by rotating a rotating shaft. In the motor casing, cooling water for cooling the heat generated by the rotation of the rotating shaft is circulated while being cooled by the circulation cooling mechanism (see Patent Document 1).

  However, this circulation pump further requires a space for disposing the motor casing and a space for disposing the circulation cooling mechanism at the lower part of the space for disposing the pump casing. For this reason, the construction cost of the equipment is extremely high, and the maintenance work is very complicated. That is, when the pump casing is installed so as to be positioned on the ground, it is necessary to dig up a large machine place in order to secure a space for disposing the motor casing and the circulation cooling mechanism. On the contrary, when installing the motor casing and the circulating cooling mechanism so as to be located on the ground, it is necessary to provide a foundation and a building for installing the motor casing and the connecting pipe connected to the motor casing at a high position on the ground. There is. Therefore, the construction cost of facilities becomes extremely high.

  In order to solve this problem, it is conceivable to install (upright type) so that the pump casing is located below the motor casing. This eliminates the need for large foundations and buildings, thus reducing construction costs.

  However, when the circulation pump is arranged upright, the hot water in the lower pump casing and the cooling water in the upper motor casing are located in the middle during the warm standby when the rotation of the rotary shaft is stopped. Natural convection through the axial penetration of the barrier. As a result, the hot water on the pump casing side enters the motor casing, while the cooling water on the motor casing side enters the pump casing. As a result, the water replacement phenomenon raises the problem that the temperature of the cooling water in the motor casing rises and the motor mechanism is overheated (thermal damage to the motor insulator). Moreover, the problem (loss of boiler calorie | heat amount) that the hot water (canned water) in a pump casing is cooled arises. This problem does not occur when the pump casing is positioned upside down on the motor casing. In both the upright type and the inverted type, the operation is not caused by the water flow in which the cooling water is circulated by the circulation cooling mechanism during operation with the rotating shaft rotated.

JP 2000-338287 A

  It is an object of the present invention to provide a circulation pump that is an upright type that can reduce the cost of constructing equipment and that can solve the problems caused by the water replacement phenomenon that occurs in this upright type.

In order to solve the above problems, the circulating pump according to the present invention is disposed in the pump casing by the rotation of the rotating shaft disposed from the motor casing located at the upper end to the pump casing located at the lower end through the shaft penetration part of the heat barrier. The circulating pump is configured to rotate the impeller provided to suck hot water from the suction portion of the pump casing and discharge it from the discharge portion, while circulating the cooling water in the motor casing while being cooled by a circulation cooling mechanism. In addition, a pump for sucking the cooling water in the motor casing and circulatingly supplying it is provided in the connection pipe of the circulation cooling mechanism.
Specifically, the pump is a canned motor type pump.

  This circulation pump is an upright type in which the pump casing is located at the lower part of the motor casing. Therefore, when constructing the equipment, a large foundation or building for disposing the motor casing and the circulation cooling mechanism is not necessary, so that the equipment construction cost can be reduced.

  Further, in the circulation pump, the cooling water in the motor casing can be forcibly circulated by the pump disposed in the connection pipe of the circulation cooling mechanism during the warming standby in which the rotation of the rotation shaft is stopped. Therefore, hot water in the pump casing does not flow into the motor casing, and cooling water in the motor casing does not flow into the pump casing. As a result, the electrical insulator can be prevented from being damaged due to an abnormal increase in the temperature inside the motor casing. Moreover, the loss of boiler heat quantity by the hot water in a pump casing being cooled can be prevented.

In this circulation pump, it is preferable that a discharge pipe for discharging the gas in the motor casing to the outside is connected to the upper end of the motor casing. In this way, it is possible to prevent damage caused by the rotating shaft being in an idling state by the dissolved gas, which is one of the gases that may naturally occur with time in the motor casing.
In this case, it is preferable to connect the discharge pipe to a suction-side boiler pipe that supplies hot water to a suction portion of the pump casing. Here, the suction-side boiler piping does not become higher than the internal pressure of the motor casing both during operation and during warm-up. Therefore, a flow always flows from the motor casing to the suction side boiler piping, and backflow can be prevented.
Further, it is preferable that a check valve that allows a flow from the motor casing toward the suction-side boiler pipe and prevents a reverse flow is disposed in the discharge pipe. If it does in this way, it can prevent reliably that the hot water in a suction side boiler piping flows in into a motor casing by unexpected pressure fluctuation.

  Since the circulation pump of the present invention is an upright type in which the pump casing is positioned at the lower part of the motor casing, a large foundation or building is not required for disposing the motor casing and the circulation cooling mechanism. Construction cost can be reduced. Moreover, since the cooling water in the motor casing can be forcibly circulated by the pump disposed in the connection pipe of the circulation cooling mechanism, the hot water in the pump casing does not flow into the motor casing, Cooling water does not flow into the pump casing. Therefore, it is possible to prevent damage to the electrical insulator due to abnormal rise in the temperature in the motor casing, and it is possible to prevent loss of boiler heat due to cooling of hot water in the pump casing.

It is sectional drawing which shows the circulation pump of embodiment which concerns on this invention. It is a principal part expanded sectional view of FIG. It is principal part sectional drawing of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 to 3 show a circulation pump according to an embodiment of the present invention. The circulation pump includes a motor casing 10 positioned on the upper side, a heat barrier 21 positioned below the motor casing 10, and a pump casing 32 positioned below the heat barrier 21. A rotating shaft 36 is rotatably supported inside these components, an impeller 39 is disposed at the lower end thereof, and an impeller 41 for circulating the cooling water is disposed at the upper end. The motor casing 10 is connected to a circulation cooling mechanism 42 that cools and circulates internal cooling water. In the present invention, the connection pipe 43 of the circulation cooling mechanism 42 is provided with a pump 47 that can forcibly circulate the cooling water in the motor casing 10 even during the warm standby in which the rotation of the rotary shaft 36 is stopped. Is.

  The motor casing 10 is formed by closing the upper end of a substantially cylindrical motor casing body 11 with a cooling water impeller case 15. The motor casing main body 11 is provided with a rotating shaft support portion 12 penetrating along the axial direction at the center of the upper end closing portion. The rotating shaft support 12 has a cylindrical shape extending into the motor casing body 11, and an upper sleeve 13 is disposed on the inner periphery thereof. The motor casing body 11 is provided with a motor stator 14 at an internal intermediate position. The motor stator 14 includes a cylindrical core block formed by laminating thin electromagnetic steel plates, and a coil bundle wound through a plurality of grooves disposed on the inner diameter side of the core block. ing.

  The cooling water impeller case 15 has a substantially conical cylindrical shape, and a cooling water impeller disposition portion 16 is formed at the lower end opening thereof. A water injection pocket 17 made of a substantially cylindrical space is formed in the upper portion of the cooling water impeller disposition portion 16. A water injection port 18 for connecting the connection pipe 43 of the circulation cooling mechanism 42 is provided on the outer periphery of the water injection pocket 17. The upper end opening of the cooling water impeller case 15 is closed by a motor cover 19. The motor cover 19 is provided with a discharge port 20 for connecting a discharge pipe 49 of the gas discharge mechanism 48.

  The heat barrier 21 is provided with a heat insulating space 22 inside, and is disposed in a watertight state at a lower portion of the motor casing 10. As shown in FIG. 2, the heat barrier 21 is provided with a shaft penetrating portion 23 formed of a hole penetrating in the axial direction so as to be positioned at the center. The upper part of the shaft penetration part 23 is a rotary shaft support part 24 having an enlarged diameter. A lower sleeve 25 that rotatably supports the lower portion of the rotating shaft 36 is disposed inside the rotating shaft support portion 24. Further, the heat barrier 21 is provided with a high-pressure cooling water passage 26 penetrating in the radial direction from the outer peripheral portion to the rotating shaft support portion 24. The outer end of the high-pressure cooling water passage 26 constitutes a spout for connecting the connection pipe 43 of the circulation cooling mechanism 42.

  Further, the heat barrier 21 is provided with a low-pressure cooling water channel 27 so as to be positioned above the heat insulating space 22. As shown in FIG. 3, the low-pressure cooling water passage 27 is a plurality of (four in this embodiment) perforated so as to be located on the outer periphery of the shaft penetration portion 23 without intersecting the shaft penetration portion 23 and the high-pressure cooling water passage 26. Book) linear through holes 28a to 28d. For example, one end of the first through hole 28a is used as an inlet and the other end is closed. Moreover, the 2nd through-hole 28b is formed so that it may cross | intersect the 1st through-hole 28a, and the both ends are obstruct | occluded. Further, a third through hole 28c is formed so as to intersect with the second through hole 28b, and both ends thereof are closed. Then, a fourth through hole 28d is formed so as to intersect with the third through hole 28c, one end thereof is closed, and the other end is used as an outlet. Thus, a water channel is formed which communicates from the inlet at one end of the first through hole 28a to the outlet at the other end of the fourth through hole 28d. And it is set as the structure which aims at the heat insulation with the motor casing 10 side and the pump casing 32 side by letting the low pressure cooling water from the low pressure cooling water supply mechanism which is not shown in figure into this water channel. 1 and 2 are formally arranged at opposing positions in order to illustrate the high-pressure cooling water channel 26 and the low-pressure cooling water channel 27.

  The heat barrier 21 of the present embodiment is provided with a flow suppression mechanism 29 for suppressing fluid movement in the shaft penetration part 23. The flow suppression mechanism 29 is for suppressing the cooling water from flowing from the motor casing 10 to the pump casing 32 through the shaft penetrating portion 23 and the hot water from flowing from the pump casing 32 to the motor casing 10. It is. In order to prevent this bidirectional flow, in this embodiment, as shown in FIG. 2, a labyrinth-type shaft seal 30 is disposed so as to be positioned below the rotary shaft support portion 24 of the shaft penetration portion 23. is doing. The shaft seal 30 has a cylindrical shape disposed on the inner peripheral portion of the shaft penetrating portion 23, and a plurality of annular grooves 31 are provided on the inner peripheral surface so as to form an annular shape.

  The pump casing 32 is a hollow shape having a substantially hemispherical shape, and is disposed in a watertight state below the heat barrier 21. The pump casing 32 is provided with a cylindrical suction portion 33 that protrudes along the axial direction of the motor casing 10 and protrudes radially outward so as to intersect the axial direction of the suction portion 33. A cylindrical discharge portion 34 is provided. The inside of the pump casing 32 is partitioned by a guide vane 35 for guiding the hot water sucked from the suction portion 33 to the discharge portion 34.

  The rotary shaft 36 is disposed through the shaft penetrating portion 23 of the heat barrier 21 from the hollow motor casing 10 to the pump casing 32. In the present embodiment, the rotary shaft body 37 disposed in the motor casing body 11, the shaft portion 39 a formed on the impeller 39 disposed in the pump casing 32, and the cooling water impeller case 15 are disposed. One rotating shaft 36 is configured by integrally connecting a shaft portion 41 a formed on the cooling water circulation impeller 41. Therefore, the rotation shaft 36 that penetrates the shaft penetration portion 23 of the heat barrier 21 is the shaft portion 39 a of the impeller 39. Of course, these shaft portions 39a and 41a can be integrally formed with the rotary shaft main body 37.

  The rotation shaft 36 is rotatably supported by the upper sleeve 13 and the lower sleeve 26. A motor rotor 38 is disposed on the rotary shaft 36 so as to be located radially inward with respect to the motor stator 14. The motor rotor 38 includes a cylindrical block in which electromagnetic steel plates are laminated, a plurality of copper bars penetrating the inside of the surface layer side of the block, and a copper ring that collectively connects both ends of each bar. . The motor rotor 38 is affected by the rotating magnetic field generated by the coil of the motor stator 14 and is rotated by an electromagnetic force generated by the action of the rotating magnetic field when a current due to electromagnetic induction flows through the copper bar. It is.

  The impeller 39 is disposed in the guide vane 35 of the pump casing 32. The impeller 39 is provided with a shaft portion 39 a protruding from a disc-shaped main plate to the rotary shaft main body 37. Impeller blades 40 are provided on the lower surface side of the main plate of the impeller 39, and hot water sucked from the suction part 33 of the pump casing 32 is discharged from the discharge part 34 by the impeller blades 40.

  The cooling water circulation impeller 41 constitutes a part of a circulation cooling mechanism 42 that circulates and supplies cooling water in the motor casing 10 during operation with the rotating shaft 36 rotated. Arranged in the case 15. The cooling water circulation impeller 41 is provided with a shaft portion 41 a that is connected to the rotary shaft main body 37 from a disk-shaped main plate. The cooling water circulation impeller 41 is formed with a suction flow path that opens to face the water injection pocket 17 and a discharge flow path that extends radially outward from the lower end of the suction flow path. . Through this flow path, the cooling water circulation impeller 41 sucks the cooling water in the upper water injection pocket 17 downward and discharges it radially outward, so that the downward water flow in the motor casing main body 11 through the rotating shaft support portion 12. Is granted.

  The circulation cooling mechanism 42 includes a connection pipe 43 that connects the water inlet 18 of the water injection pocket 17 that is the upper part of the motor casing 10 and the outlet of the heat barrier 21 that is the lower part of the motor casing 10 so as to bypass. Yes. The connection pipe 43 is provided with a motor cooler 44 at a portion extending upward. The motor cooler 44 includes a low-pressure cooling water inlet 45 and a low-pressure cooling water outlet 46. When the low-pressure cooling water is supplied from a low-pressure cooling water supply mechanism (not shown), the heated water that flows through the connection pipe 43 is heated. It is to be cooled.

  The pump 47 is a canned motor type pump that is provided upstream of the motor cooler 44 in the connection pipe 43 of the circulation cooling mechanism 42. The pump 47 sucks the cooling water in the motor casing 10 on the upstream side, and circulates and supplies the cooling water to the water injection pocket 17 on the downstream side via the motor cooler 44. The canned motor type pump 47 is a motor coil that is sealed in a can and can be used in water.

  Further, the circulation pump of the present embodiment is further provided with a gas discharge mechanism 48 for discharging the gas generated inside the motor casing 10 to the outside. The gas discharge mechanism 48 includes a discharge pipe 49 connected to the discharge port 20 at the upper end of the motor casing 10, and an orifice 50 and a check valve 51 interposed in the discharge pipe 49. The discharge pipe 49 is piped so as to incline upward, and its tip is branched and connected to the suction-side boiler pipe 52. The orifice 50 stably maintains a small amount of fluid flowing out of the motor casing 10. The check valve 51 allows a flow from the motor casing 10 toward the suction side boiler pipe 52 and prevents a reverse flow.

  In the circulation pump configured as described above, the suction side boiler piping 52 is connected to the suction portion 33 of the pump casing 32, and the discharge side boiler piping 53 is connected to the discharge portion 34 of the pump casing 32. In the power generation equipment that is one example of use of the circulation pump of the present embodiment, the discharge-side boiler pipe 53 is connected to a boiler that generates water by overheating water, and the suction-side boiler pipe 52 generates high-temperature steam. Connected to a condenser for hot water. And a power generation installation rotates the turbine connected with the generator with the steam produced | generated with the boiler. The steam that has rotated the turbine is returned to hot hot water by a condenser. This hot water is circulated and supplied by the circulation pump of this embodiment.

  Next, the operation of the circulation pump of this embodiment will be specifically described.

  First, the low-pressure cooling water passage 27 of the heat barrier 21 and the motor cooler 44 of the circulation cooling mechanism 42 are low in both the operation state in which the rotating shaft 36 is rotated and the warm-up state in which the rotating shaft 36 is stopped. Low-pressure cooling water is always supplied from the cooling water supply mechanism.

  During operation, the impeller 39 and the cooling water circulation impeller 41 are rotated by the rotation of the rotating shaft 36. Thereby, in the pump casing 32, the impeller 39 rotates to suck in hot water from the condenser via the suction side boiler pipe 52 and circulate and supply hot water to the boiler. Further, in the motor casing 10, a water flow in which the cooling water flows downward in the motor casing 10 is given by the rotation of the cooling water circulation impeller 41. Then, the cooling water at the lower part of the motor casing 10 is sucked into the connection pipe 43, cooled by the motor cooler 44, and circulated and supplied to the water injection pocket 17. The circulating flow of the cooling water by the circulation cooling mechanism 42 prevents natural convection between the cooling water in the motor casing 10 and the hot water in the pump casing 32 through the shaft penetrating portion 23.

  On the other hand, during the warm standby, the rotary shaft 36 is stopped, so that the impeller 39 and the cooling water circulation impeller 41 are stopped. Thereby, in the pump casing 32, circulation supply of hot water is stopped. Further, in the motor casing 10, the cooling water flow (circulation) by the cooling water circulation impeller 41 is stopped. In this state, the pump 47 interposed in the connection pipe 43 of the circulation cooling mechanism 42 is driven. As a result, in the motor casing 10, the cooling water at the lower part of the motor casing 10 is sucked into the connection pipe 43, cooled by the motor cooler 44, and circulated and supplied to the water injection pocket 17 as during operation. As a result, during this warm standby, the cooling water circulating flow similarly prevents natural convection between the cooling water in the motor casing 10 and the hot water in the pump casing 32 through the shaft penetrating portion 23.

  Moreover, in the motor casing 10, the dissolved gas which is one of the gas may generate | occur | produce naturally with time. This gas causes an idle operation phenomenon in the rotary shaft 36 during operation. However, in this embodiment, the discharge pipe 49 is connected to the upper end of the motor casing 10. The gas generated in the motor casing 10 accumulates in the water injection pocket 17 which is the upper end of the motor casing 10 in both the operating state and the warming standby state, and is discharged to the suction-side boiler pipe 52 through the discharge pipe 49. . Specifically, the suction-side boiler pipe 52 does not become higher than the internal pressure of the motor casing 10 both during operation and during warm standby. Therefore, a flow from the motor casing 10 toward the suction side boiler pipe 52 is always generated, and gas can be discharged. However, when gas and liquid are discharged to the suction-side boiler pipe 52 through the discharge pipe 49, hot water corresponding to the discharge amount flows from the pump casing 32 into the motor casing 10 through the shaft penetration part 23. The amount is set to be extremely small by the shaft seal 30 and the orifice 50. Moreover, the hot water that has flowed in is not directly flown into the motor casing 10, but is cooled by the motor cooler 44 through the connecting pipe 43 and injected from the injection pocket at the upper end. Therefore, the temperature of the cooling water in the motor casing 10 does not rise.

  Thus, in the circulation pump of the present invention, the cooling water in the motor casing 10 is forcibly supplied by the pump 47 disposed in the connection pipe 43 of the circulation cooling mechanism 42 during the warm-up standby in which the rotation of the rotary shaft 36 is stopped. It can be circulated. Therefore, hot water in the pump casing 32 does not flow into the motor casing 10, and cooling water in the motor casing 10 does not flow into the pump casing 32. As a result, the electrical insulator can be prevented from being damaged due to an abnormal increase in the temperature in the motor casing 10. Moreover, the loss of boiler heat quantity by the hot water in the pump casing 32 being cooled can be prevented.

  In addition, a discharge pipe 49 is connected to the upper end of the motor casing 10 in the circulation pump of the present embodiment so that gas generated in the motor casing 10 can be discharged to the suction side boiler pipe 52. Therefore, it is possible to prevent damage due to the rotating shaft 36 being in an idling state during operation. Further, since the check valve 51 is provided in the discharge pipe 49, it is possible to reliably prevent hot water in the suction-side boiler pipe 52 from flowing into the motor casing 10 due to unexpected pressure fluctuations.

  Since the circulation pump of the present invention is an upright type in which the pump casing 32 is positioned below the motor casing 10, the motor casing 10 and the circulation cooling mechanism 42 are disposed at the time of construction of the equipment. Since large foundations and buildings are not required, equipment construction costs can be reduced.

  In addition, the circulation pump of this invention is not limited to the structure of embodiment, A various change is possible.

  For example, in the above-described embodiment, the cooling water circulation impeller 41 is provided as one of the circulation cooling mechanisms 42, the cooling water is circulated and supplied by the cooling water circulation impeller 41 during operation, and the cooling water is cooled by the pump 47 during warm standby. However, the cooling water circulation impeller 41 may not be provided, and the cooling water may be circulated and supplied by the pump 47 during both operation and warm standby.

  In the above embodiment, the guide vane 35 is disposed in the pump casing 32. However, the guide vane 35 may not be disposed. Furthermore, the pump casing 32 is not limited to the one in which the discharge portion 34 protrudes radially outward with respect to the axial direction of the suction portion 33, and may be a spiral shape having a spiral flow channel.

  In the above embodiment, the motor mechanism disposed in the motor casing 10 has the motor stator 14 and the motor rotor 38 and rotates by the action of the rotating magnetic field. However, the motor mechanism includes the presence or absence of a magnet. The type of can be changed as desired.

  And in the said embodiment, although the example which uses the circulation pump of this invention for power generation equipment was given and demonstrated, the use application is not restricted to power generation equipment.

DESCRIPTION OF SYMBOLS 10 ... Motor casing 21 ... Heat barrier 23 ... Shaft penetration part 26 ... High pressure cooling water channel 27 ... Low pressure cooling water channel 32 ... Pump casing 33 ... Suction part 34 ... Discharge part 36 ... Rotating shaft 39 ... Impeller 42 ... Circulation cooling mechanism 43 ... Connection Pipe 44 ... Motor cooler 47 ... Pump 48 ... Gas discharge mechanism 49 ... Drain pipe 51 ... Check valve 52 ... Suction side boiler piping 53 ... Discharge side boiler piping

Claims (5)

The rotation of the rotating shaft arranged from the motor casing located at the upper end to the pump casing located at the lower end through the shaft penetration part of the heat barrier causes the impeller arranged in the pump casing to rotate, thereby supplying hot water to the pump casing. A circulation pump that circulates while cooling the cooling water in the motor casing while being cooled by a circulation cooling mechanism while sucking from the suction portion and discharging from the discharge portion,
A circulation pump characterized in that a pump for sucking the cooling water in the motor casing and circulatingly supplying it is disposed in a connection pipe of the circulation cooling mechanism.   The circulating pump according to claim 1, wherein the pump is a canned motor type pump.   The circulation pump according to claim 1 or 2, wherein a discharge pipe for discharging the gas in the motor casing to the outside is connected to an upper end of the motor casing.   The circulation pump according to claim 3, wherein the discharge pipe is connected to a suction-side boiler pipe that supplies hot water to a suction portion of the pump casing.   The circulation pump according to claim 4, wherein a check valve that allows flow from the motor casing toward the suction-side boiler pipe and prevents reverse flow is disposed in the discharge pipe.

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