JPH07119700A - Jet pump - Google Patents

Abstract

PURPOSE:To reduce a pressure loss and cavitation by providing plural outer peripheral side nozzle parts projected to the suction side on the outside concentric circle of a center side nozzle part, and making the respective outer peripheral side nozzle parts shorter than the center side nozzle part. CONSTITUTION:A multi-stage accelerating rotary driven water nozzle 32 is so constructed that a center nozzle 36 is provided in the shaft center part, and outer peripheral rotary nozzles 37a-37d which are plural outer peripheral side nozzle parts are disposed in the circumferential direction by equal pitches on the concentric circle on the outside of the center nozzle. The center nozzle 36 and the outer peripheral rotary nozzles 37a-37d are connected integrally to each other by branch pipes 38a-38d projected radially on the side of the center nozzle 36. Further, the length of projection of each outer peripheral rotary nozzle 37a-37d is made a little smaller than that of the center nozzle 36, and the central axis ''a of the center nozzle 36 is coaxially aligned with the central axis Ob of a diffuser. Thus, a fluid can be accelerated by different sections so as to decrease a pressure loss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jet pump suitable for boiling water reactors and the like, and more particularly to a jet pump having improved efficiency.

[0002]

2. Description of the Related Art Conventionally, as an example of this type of jet pump, there is known a jet pump configured as shown in a front view of FIG. 19A and a side view of FIG. This jet pump 1 causes a driving fluid having a high total pressure to be jetted to a bell mouth 3 at a higher speed than a nozzle 2a of a nozzle portion 2 by an external pump as shown by an arrow in FIG. The driven body around the bell mouth 3 is sucked into the bell mouth 3 and guided to the throat 4 together with the driving fluid. In the throat 4, the driving fluid and the driven fluid are mixed, kinetic energy is converted into pressure energy while passing through the diffuser 5, and the pressure is higher than the pressure of the driven fluid before being sucked from the discharge port 5e of the diffuser 5. Be exhaled.

By the way, since high-speed fluid flows near the nozzle 2a, the throat 4 and the diffuser 5 are detachably connected by the throat flange joint 6 so that the nozzle portion 2 and the throat 4 can be exchanged, while the riser flange joint 7 is connected. The nozzle portion 2 and the riser pipe 8 are detachably connected with each other.

The nozzle portion 2 has a first bending portion 1B and a second bending portion 1B.
The bending portion 2B and the bending portion 2B are bent in the same plane to form a U-shape, and the tip portion of the riser pipe 8 is formed at the third bending portion 3B at a right angle to the tube axis surfaces of the first and second bending portions 1B and 2B. Is bent in the direction
The length between the third bent portion 3B and the second bent portion 2B is about 20 times the inner diameter r of the riser pipe or more.

FIG. 20 shows the flow rate and pressure of each part of the jet pump 1. In the figure, P is pressure (total pressure)
Q indicates the flow rate, and subscripts n, s, and d indicate the nozzle flow (driving flow), the suction flow (driven flow), and the diffuser flow (discharging flow), respectively.

Generally, the performance of the jet pump 1 is as follows: flow rate ratio (hereinafter referred to as M ratio), M ratio = Qs / Qn, pressure ratio (hereinafter referred to as N ratio), N ratio = (Pd-Ps / Pn-P
d). The efficiency η of the jet pump 1 is represented by η = M ratio × N ratio × 100 (%).

FIG. 21 shows a structure of a jet pump 1 configured as described above in a boiling water reactor (hereinafter referred to as "BWR") which is used for controlling a reactor power by circulating a coolant in a reactor pressure vessel 10. An example of the case where it is incorporated in a circulatory system is shown. A plurality of jet pumps 1 are arranged in the downcomer section of the reactor pressure vessel 10 and driven by reactor water.

That is, the driving water for the jet pump 1 is supplied to the suction pipe 12 below the core 11 in the reactor pressure vessel 10.
Reactor water sucked from the reactor is pressurized by the recirculation pump 13, and this drive water is branched into a plurality of branch pipes and then jetted from the nozzle 2a of the jet pump 1 through the riser pipe 8. For this reason, the static pressure around the bell mouth 3 decreases, and the reactor water around the bell mouth 3 is sucked in,
The driving water and the driven water are mixed in the throat 4, the pressure is increased in the diffuser 5, and the pressure is discharged again into the reactor pressure vessel 10 through the discharge port 5e. This nuclear reactor recirculation system has, for example, two systems, and the jet pump 1 has an M ratio of about 2
It is a degree. Therefore, about 1/6 of the core flow rate will flow through the suction pipe 12, and therefore the suction pipe 12 needs to have a diameter of about 600 A for a 1100 MWe class BWR, and is the maximum except for the main steam pipe. Caliber of.
Therefore, emergency core cooling system (hereinafter referred to as ECCS)
Is designed to have a sufficient supply capacity for a coolant loss accident (hereinafter referred to as LOCA) event due to the breakage of the suction pipe 12.

[0009]

However, when such a large-diameter suction pipe 12 is broken, a large amount of reactor water suddenly flows out, and the capacity of the ECCS system becomes very large. As a countermeasure, in order to reduce the diameter of the suction pipe 12, it is possible to secure the core flow rate by a small flow rate of the driving water, and for that purpose, the M ratio of the jet pump 1 may be made larger than the current state. As a result, the diameter of the suction pipe 12 of the recirculation pump 13 can be reduced, so that the outflow rate at the LOCA event at the time of breakage of the suction pipe 12 can be reduced, safety can be improved, and ECCS can be improved. The system capacity can also be reduced.

As one of the methods for increasing the M ratio of the jet pump 1, it is known to reduce the area ratio of the nozzle 2a / throat 4 (hereinafter referred to as the R ratio).

FIG. 22 shows the M ratio of the current jet pump 1.
The efficiency curve 14 and the M ratio-efficiency curve 15 of the jet pump 1 in which the R ratio is reduced to the high M ratio side are shown respectively, but when the R ratio is reduced, the speed of the driving water flow is reduced to that of the conventional jet pump. 1, the friction loss, the energy transfer loss to the driven fluid and the like increase, and the efficiency significantly decreases. When this efficiency is lowered, it is necessary to increase the capacity of the recirculation pump 13 by that amount, and as a result, the economical efficiency including the operating cost is lowered. In order to prevent this, it is necessary to improve the efficiency of the jet pump 1.

Further, in the conventional nuclear reactor recirculation system, the jet pump 1 is driven by the recirculation pump 13 as shown in FIG. 21, but since the recirculation pump 13 has a rotating portion, the nuclear power plant A lot of man-hours were required for the periodic inspection of.

Further, as shown in FIG. 21, the recirculation pump 13 is installed in the reactor containment vessel 16, and since many devices are housed in this reactor containment vessel 16. It is narrow and poor in workability. In addition, a trouble caused by the rotating part or the like may occur, which may reduce the operating rate of the plant.

Therefore, the recirculation pump 13 in the reactor containment vessel 16 is deleted, and the water supply from the water supply pump 17 outside the reactor containment vessel 16 is directly sent to the jet pump 1, so-called water supply drive jet. A reactor plant using a pump is possible.

The main purpose of this reactor water supply system is to replenish the amount of steam extracted from the reactor pressure vessel 10 to the steam turbine 19 through the main steam pipe 18, and by adjusting the supply water flow rate, Keeps the water level constant. This feed water flow rate is about 1/6 of the reactor water flow rate.

The water supply jet pump system is a system that uses this water supply as a drive source of the jet pump 1, and the water supply system is branched into two systems in the middle of the water supply pipe 20.
One of them is boosted by a booster pump, then guided to a nozzle portion 2 of a jet pump 1 and ejected from a nozzle 2a,
The jet pump 1 is operated. The other one is injected into the reactor pressure vessel 10 from the water supply sparger.

By adopting this system, the suction pipe 12 of the recirculation pump 13 in the existing BWR described above can be eliminated, so that the safety of the nuclear reactor is greatly improved,
Further, it is possible to significantly reduce the ECCS system capacity.

However, all of this water supply is jet pump 1
When it is used as the driving water, since it becomes difficult to adjust the reactor water as described above, only about 60 to 80% of the feed water flow rate can be actually used. Considering that the total feed water flow rate is about ⅙ of the core flow rate, it is necessary to increase the M ratio of the jet pump 1 to about 10 times. As a result, the efficiency of the jet pump 1 is significantly increased as described above. The problem with this feedwater jet pump system is that it drops to zero.

Further, by increasing the efficiency of the jet pump 1 used in the existing BWR, it is expected that the capacity of the recirculation pump 13 and the running cost can be reduced.

By the way, in the conventional jet pump 1 shown in FIG. 19, the driven water jetted from the single nozzle 2a accelerates the driven water in one step, that is, in the same step surface, so that a swirl easily occurs. There is a problem that the pressure loss is large.

That is, in the conventional jet pump 1, since the pressure is distributed as shown in FIG. 23 obtained as a result of the flow analysis, the pressure in the downcomer portion of the reactor pressure vessel 10 is set to the reference pressure (0, 0). Then, as shown in a partially enlarged view of FIG. 24, a strong negative pressure portion is generated in a portion from the bell mouth 3 to the inlet of the throat 4, and cavitation is likely to occur.

Further, as shown in the velocity vector diagram of FIG. 25 and its enlarged view of FIG. 26, in the portion from the bell mouth 3 to the inlet of the throat 4 (particularly A portion in FIG. 26), the driving water and the Since the relative speed difference of the driving water is very large, if the bell mouth 3 is small, the driven water cannot be smoothly sucked in, and a vortex is likely to occur.

Further, since the throat 4 for mixing the driving water and the driven water to exchange the momentum is long, the pressure loss is large and the pressure loss at the inlet of the diffuser 5 is large. As shown in the figure, there is a problem that flow separation occurs in a portion such as B in the diffuser 5, pressure loss increases and efficiency decreases, and it is difficult to obtain a sufficient recirculation flow rate.

Therefore, the present invention has been made in consideration of such circumstances, and an object thereof is to provide a jet pump of high efficiency.

[0025]

The present invention is configured as follows in order to solve the above-mentioned problems.

The invention according to claim 1 of the present application (hereinafter, referred to as the first
Of the invention), the driving fluid is ejected from the nozzle to the suction port, thereby sucking the driven fluid around the suction port, mixing the driving fluid and the driven fluid in the throat portion, and increasing the pressure in the diffuser portion. In the jet pump that discharges after that, the nozzle is provided with a central nozzle portion protruding from the axial center portion thereof toward the suction port side, and on the concentric circle outside the central side nozzle portion toward the suction port side. It is characterized in that it has a plurality of outer peripheral side nozzle parts that are projected, and each of these outer peripheral side nozzle parts is made shorter than the central side nozzle part.

In the invention according to claim 2 of the present application (hereinafter referred to as the second invention), the central nozzle portion has its ejection central axis aligned with the central axis of the throat portion, while each outer peripheral nozzle portion The part is characterized in that each of the ejection angles is inclined at a required angle in the same circumferential direction of the suction port.

Further, in the invention according to claim 3 of the present application (hereinafter referred to as the third invention), the outer peripheral side nozzle portions are arranged at equal pitches in the circumferential direction, and the respective ejection angles thereof are determined by the throat portion. It is characterized in that it is inclined at a required angle toward an arbitrary point on the central axis of.

Furthermore, in the invention according to claim 4 of the present application (hereinafter, referred to as a fourth invention), the central side nozzle portion and each outer peripheral side nozzle portion are provided with serrated notches at their tip ends. It is characterized by being formed.

The invention according to claim 5 of the present application (hereinafter referred to as the fifth invention) is a cluster type in which the central nozzle portion and each outer peripheral nozzle portion are radially connected by a branch pipe. It is characterized by being configured.

Further, in the invention according to claim 6 of the present application (hereinafter, referred to as a sixth invention), the diffuser portion is formed in a truncated cone shape that expands in a truncated cone shape toward the fluid discharge port. It is characterized by

Furthermore, in the invention according to claim 7 of the present application (hereinafter referred to as the seventh invention), the diffuser portion is formed in a trumpet shape which expands in a trumpet shape toward the fluid discharge port. It is characterized by

In the invention according to claim 8 of the present application (hereinafter referred to as the eighth invention), the diffuser portion is formed in a bell shape that expands in a bell shape toward the fluid discharge port. Is characterized by.

Further, in the invention according to claim 9 of the present application (hereinafter referred to as the ninth invention), at least one of the diffuser portion and the throat portion is provided with fins or grooves for generating a swirling flow on the inner surface thereof. It is characterized by being

Furthermore, in the invention according to claim 10 of the present application (hereinafter referred to as the tenth invention), the drive fluid is ejected from the nozzle to the suction port to suck the driven fluid around the suction port, In a jet pump that mixes the driving fluid and the driven fluid in a throat portion, pressurizes them in a diffuser portion, and then discharges them, the upstream flow path of the nozzle is three-dimensionally bent.

The invention according to claim 11 of the present application (hereinafter referred to as the eleventh invention) has at least three fluid bending portions, and the tube axis surface of the middle bending portion is bent at both ends. It is characterized in that it is perpendicular to the tube axis surface of each part.

Further, in the invention according to claim 12 of the present application (hereinafter referred to as the twelfth invention), there are two fluid bending portions, and the tube axial surfaces of these bending portions are perpendicular to each other, and It is characterized in that the length between the bent portions is set within 10 times the flow path diameter.

[0038]

[Action]

<First to Ninth Inventions> When the driving fluid is ejected from the central nozzle portion and the plurality of outer peripheral nozzle portions to the suction port, the driven fluid around the suction port is sucked into the bell mouth. However, since each outer peripheral side nozzle section has a shorter nozzle length than the central side nozzle section, the drive fluid ejected from each outer peripheral side nozzle section accelerates the drive fluid abruptly,
After that, the driven fluid is accelerated by the driving fluid ejected from the central nozzle portion.

That is, according to the present invention, the driven fluid is accelerated by the driving fluid in multiple (2) steps in the axial direction, that is, in a stepwise manner, so that the pressure loss is reduced as compared with the conventional example in which the fluid is accelerated in one step. It is possible to reduce or prevent cavitation and increase the efficiency of the jet pump.

<Second and Third Inventions> Since the ejection angles of the outer peripheral side nozzle portions are inclined in the same direction in the circumferential direction of the suction port,
A swirling flow is generated in the driving fluid ejected from each outer peripheral nozzle side to the suction port side. Therefore, the driven fluid around the suction port can be smoothly sucked into the suction port, and the vortex loss and cavitation of the flow around the suction port can be reduced or prevented to increase the suction flow rate. The efficiency of can be improved.

<Fourth Invention> Since the nozzle-shaped notch is formed at the tip of each nozzle, a run-up section for contact between the driving fluid and the driven fluid is formed, so that a sudden driving fluid can be used. It is possible to prevent the occurrence of cavitation due to the acceleration of the driving fluid.

<Seventh Invention> In the trumpet type diffuser portion, since the area increase rate in the axial direction can be suppressed at the diffuser inlet portion where the flow velocity is high, the separation of the flow in the diffuser can be suppressed to a minimum.

<Eighth Invention> The bell-shaped diffuser portion is
A slight flow separation occurs at the diffuser inlet where the flow velocity is fast, but the separation is redeposited at the downstream part. This reattachment flow is generally less prone to flow separation, so again flow separation in the diffuser can be minimized.

<Ninth invention> Since at least one of the diffuser portion and the throat portion is provided with a fin or groove for generating a swirling flow, a swirling flow is generated in the fluid,
Fluid separation in the diffuser portion and the throat portion can be reduced or prevented, and the diffuser efficiency can be improved.

<10th to 12th inventions> Since the driving body flow path is three-dimensionally bent on the upstream side of the nozzle portion of the jet pump, a swirling flow is generated in the driving fluid ejected from this nozzle toward the suction port. Occurs. This swirling flow smoothly sucks the driven body around the suction port, increases the suction flow rate, promotes the mixing of the driving fluid and the driven fluid, and facilitates the exchange of the momentum of both fluids. , The efficiency of the jet pump can be increased.

[0046]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 18, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a schematic vertical sectional view showing the overall construction of an embodiment of the present invention. In the figure, a jet pump 31 is shown.
Is a jet pump suitable for, for example, the above-mentioned BWR nuclear reactor recirculation system, in which a multi-stage acceleration swirl drive water nozzle 32 for ejecting drive water is used as a suction port of a diffuser 34 having fins 33 for generating swirl flow. Face a certain bell mouth 35, and from the multi-stage acceleration swivel drive water nozzle 32 to the bell mouth 35.
By ejecting the driving water Wa to the bell mouth 35
Surrounding driven water Wb is sucked into the diffuser 34 from the bell mouth 35, and this driven water Wb is accelerated in multiple stages by the driving water Wa and discharged from the discharge port 340 of the diffuser 34.

As shown in FIG. 2, the multistage accelerating swirl drive water nozzle 32 is provided with a central nozzle 36, which is the central nozzle portion, at the axial center thereof, and a plurality of concentric circles C are provided outside the central nozzle 36. Outer peripheral swirling nozzles 37a, 37b, 37c, 37d, which are the outer peripheral side nozzle portions of the above, are arranged at equal pitches in the circumferential direction, and these center nozzle 36 and outer peripheral swirling nozzle
7a to 37d are integrally or integrally connected to each other by branch pipes 38a, 38b, 38c and 38d that are radially provided on the side surface of the central nozzle 36 to form a so-called cluster type.

Further, as shown in FIGS. 1 and 3 (a), the central nozzle 36 has a protrusion length (nozzle length) slightly longer than the protrusion length of each of the outer peripheral swivel nozzles 37a to 37d. While setting, the central axis Oa of the central nozzle 36
Is coaxially aligned with the central axis Ob of the diffuser 34.

Further, each outer peripheral turning nozzle 37a-37d.
The central axis Oc of each of the jets of the throat 3 of the diffuser 34
It is made to coincide with an arbitrary point 39a of 9. This point 39
Since a is an apex of a conical shape formed by each ejection central axis Oc, and the ejection axial direction of each outer peripheral swirling nozzle 37a to 37d is along the conical side surface of this conical apex 39a,
The flow of the driven water flowing into the bell mouth 35 can be made smooth to reduce or prevent eddy loss and cavitation of the flow.

Further, as shown in FIG. 2, each of the outer peripheral swirling nozzles 37a to 37d has its ejection port, that is, the ejection central axis O.
By tilting c by the required angle in the same circumferential direction of the concentric circle C connecting these ejection central axes Oc in the circumferential direction, a swirling flow component is given to the driving water flowing from the bell mouth 35 to the diffuser 34 via the throat 39. The boundary layer with the driven water Wb is thinned to reduce or prevent flow separation.

Moreover, as shown in FIG. 3B, saw-tooth notches 40 are formed in the center nozzle 36 and the tips of the outer peripheral swiveling nozzles 37a to 37d, respectively.
The notch depth d of these notches 40 is set to the approach section when the driving water Wa contacts and accelerates the driven water Wb, whereby the driven water Wb is rapidly accelerated by the driving water Wa. Cavitation that occurs in the case of doing so is reduced or prevented.

On the other hand, as the diffuser 34, for example, a conical shape 34a shown in FIG. 4 (a) and a trumpet shape 3 shown in FIG. 4 (b) are used.
4b, a bell shape 34c shown in FIG. The conical diffuser 34a has its side surface formed by a straight line having a required cone angle, and is formed in a shape defined as a cone or a truncated cone in geometry, and since the shape is relatively simple, Because it is easy to process,
It is used a lot today. However, if this conical diffuser 34a is used as a jet pump with a high M ratio, the axial area increases with a squared curve. Therefore, even if a swirling fin 33 for swirling flow generation is provided in the upstream part of the jet pump, Flow separation is likely to occur.

On the other hand, the trumpet diffuser 34b is shown in FIG.
As shown in (a), the side surface has a shape of an elliptic arc (trumpet shape) that expands at the discharge port 34o, and the axial area increase rate can be suppressed at the diffuser inlet with a high flow velocity, so By providing the swirling fins 33, flow separation can be suppressed to a minimum.

As shown in FIG. 5B, the bell-shaped diffuser 34c has an elliptic arc (bell-shaped, or bell-shaped) whose side surface expands at the diffuser inlet. This is from throat 39 to bell-shaped diffuser 34c
At the inlet of the diffuser with high flow velocity, the flow is intentionally minutely separated and then reattached.
It utilizes the property that a strong reattachment flow with a high flow velocity is unlikely to separate.

Then, each diffuser 34a, 34b,
The inclination angle of the swivel fin 33 of 34c is set to 15 ° ± 5 °. The reason is that, for example, in the conical diffuser 34a having a cone angle of 15 ° as shown in FIG. 5 (c), if the fin angle is less than 10 °, the fin effect is small and the flow becomes unstable. Swivel fin 3
This is because it was found by the latest computer-aided flow analysis that flow separation occurred in 3 and the pressure loss increased. The swirl fins 33 may be grooves that generate swirl flow in the fluid.

Next, the operation of this embodiment will be described.

The high-pressure drive water Wa is the central nozzle 36 of the multi-stage acceleration swirl drive water nozzle 32 and the outer peripheral swirl nozzles 37a ...
When jetted from 37d toward the bell mouth 35, first, the driving water Wa from each of the outer peripheral swirling nozzles 37a to 37d having a shorter nozzle length than the central nozzle 36 is supplied to the bell mouth 3.
5, the driven water Wb around the bell mouth 35 is sucked and accelerated, and further, the fluids Wa, Wb
In addition, a swirling flow is given by the inclination of the outer peripheral swirling nozzles 37a to 37d in the circumferential direction.

For this reason, the driven water Wb is supplied to the bell mouth 3
5 is swirled smoothly into the diffuser 34 from the bell mouth 35 through the throat 39 to give a swirling flow component to thin the boundary layer between the waters Wa and Wb to separate the flow. It can be reduced or prevented.

That is, the outer peripheral turning nozzles 37a to 37d
Since the ejection direction of the water is along the conical side surface of the conical apex 39a in the throat 39, the driven water Wb flowing into the bell mouth 35 can be smoothed to reduce or prevent flow eddy loss and cavitation. it can.

In this way, the outer peripheral turning nozzles 37a to 37d
Driven water W accelerated by driving water Wa jetted from
b is further accelerated by the high-pressure drive water Wa jetted from the central nozzle 36 next. That is, diffuser 3
Since the fluid in 4 is accelerated in multiple stages (two stages) and different cross sections by the drive water Wa, eddy loss and cavitation of the flow can be reduced or prevented, and energy can be transmitted in multiple stages. Therefore, energy loss can be reduced and acceleration performance can be improved.

Further, since the notch 40 is formed at the tip of each of the nozzles 36, 37a to 37d, an approach section is provided in the contact between the driving water Wa and the driven water Wb to gradually accelerate the driven water Wb. Therefore, it is possible to reduce or prevent cavitation that occurs when abruptly accelerating, and it is possible to reduce energy loss.

The driving water Wa and the driven water Wb mixed in the throat 39 are further diffused by the diffuser 34 (34
a, 34b, 34c), the pressure is reduced and the pressure is increased, and the liquid is discharged from the discharge port 34o.

FIG. 6 shows the M ratio-efficiency curve D of the jet pump 31 of this embodiment, the M ratio-efficiency curve E of the conventional example in which the M ratio of 7 is set to the peak, and the M ratio of 10 in the peak. It is shown by comparing with the set M ratio-efficiency curve F of the conventional example, and it can be seen that the efficiency of the jet pump 31 of the present example is significantly improved.

As described above, when the high efficiency jet pump 31 of this embodiment is applied to the recirculation system of the next-generation boiling water reactor, the high efficiency jet pump 31 makes the most of its high efficiency to make a large rotation in the reactor containment vessel. Next-generation boiling water reactor, which is a "human-friendly reactor including regular inspection workers" that does not require maintenance work in the lower part of the reactor pressure vessel or in the reactor containment vessel without installing machinery. Can be realized, and is highly practical in terms of industry and international energy policy.

The number of the outer peripheral swivel nozzles 37a to 37d is not limited to the number of nozzles in the above embodiment, and for example, as shown in FIGS. 7 (a) to 7 (c), five nozzles 37a to 37d are provided.
e, six 37a to 37f, eight 37a to 37h may be used, and the number thereof is not limited.

However, these peripheral swirling nozzles 37a-3
When the number of 7h is too large, the momentum exchange surface area of the driving water Wa increases, but at the same time, the number of the branch pipes 38a to 38h also increases. Therefore, the area of the bell mouth 35 covered by the branch pipes 38a to 38h is correspondingly increased. May increase, the opening area may decrease, and the multi-stage acceleration turning drive effect may decrease.

Further, the jet pump 5 shown in FIG.
1, the upper stage bell mouth 52 and the upper stage drive water nozzle 53 are sequentially provided in this order at the upstream end of the multi-stage acceleration swirl drive water nozzle 32 of the jet pump 31 of the above-mentioned embodiment, and the nozzle and the bell mouth are arranged in upper and lower two stages. It is characterized in that it has a high efficiency and a high M ratio by being configured. In addition, in FIG.
Reference numeral 54 is a rib that connects and supports the multi-stage acceleration swivel drive water nozzle 32 to the bell mouth 35 in the lower stage.

Further, like the jet pump 61 shown in FIG. 8B, the base end portions (upper end portions in the drawing) of the outer peripheral swirling nozzles 37a to 37d are not connected to the side surfaces of the lower central nozzle 36, but are connected to the upper stage. The extending portions 62 extending to the side surface of the driving water nozzle 53 may be integrally or integrally provided, and these extending portions 62 may be connected to the side surfaces of the first stage driving water nozzle 53, respectively. Note that the currently used reactor jet pump is divided into a plurality (two) at the upper part of the riser pipe 8 as shown in FIG. Although there is a structure in which the jet pumps 1 and 1 flow into the nozzles of the jet pumps 1, 1, the present invention can be applied to the jet pump 1 even with such a branch pipe.

According to this jet pump 61, since a part of the driving water Wa of the upper stage driving water nozzle 53 is diverted and supplied to the lower outer peripheral swirling nozzles 37a to 37d, the lower outer peripheral swirling nozzles 37a to 37d are supplied. By lowering the water temperature of the driving water Wa, it is possible to further reduce cavitation.

Further, in this embodiment, higher efficiency and M ratio can be obtained as compared with the one-stage type jet pump 31, but on the other hand, since the driving water pressure needs to be increased, one stage It is advisable to determine whether to use the formula or the two-stage formula at an M ratio of about 10 as a boundary.

9 and 10 (a) show a jet pump 71 according to another embodiment of the present invention, which is shown in FIGS.
A nozzle base 72 having a bottom and a cylindrical shape having a larger diameter than that is integrally or integrally connected to the drive water upstream end of the center nozzle 36 of the jet pump 31 shown in FIG. On the outer peripheral side of the outer peripheral swirling nozzle 37
a-37d are concentrically planted, and branch pipes 38a-38d
It is characterized by omitting.

According to this jet pump 71, since the branch pipes 38a to 38d are omitted, the structure can be simplified, and the opening of the bell masque 35 is divided into the branch pipes 38a to 38d.
Since it is less likely to be blocked by 38d, the opening area can be increased, and the suction flow rate of the driven water Wb can be increased to improve the efficiency of the jet pump.

In the jet pump 71 of this embodiment, the outer peripheral swirling nozzles 37a to 37d are arranged as shown in FIG.
Six pieces 37a to 37f may be provided as shown in FIG. 11B, and a nozzle pedestal 72 as shown in FIG.
The center nozzle 36 and the five outer peripheral swivel nozzles 37 are provided on the lower bottom surface.
The elements a to 37e may be arranged in a substantially triangular shape, and the arrangement shape thereof does not matter.

Further, as shown in FIG. 11B, for example, 4
The central nozzles 36a, 36b, 36c, 36d are arranged at equal intervals in the circumferential direction at the center of the lower bottom surface of the nozzle pedestal 72, while the four outer peripheral side nozzles 37a-37d are provided by the branch pipes 38a-38d. It may be connected to the side surface of the nozzle pedestal 72, and the number of the central nozzles 36a to 36d and the outer peripheral side nozzles 37a to 37d is not limited.

FIG. 12 compares the M ratio-efficiency curve G of the jet pump 71 shown in FIGS. 9 and 10 (a) with the M ratio-efficiency curve H of a conventional jet pump designed to have an M ratio of 10 as a peak. In this example, the efficiency of the example 71 is improved by about 3 to 4% as compared with the conventional example. That is, high efficiency can be obtained even at a high M ratio.

FIGS. 13 (a) and 13 (b) respectively show the front and side faces of a jet pump 81 according to still another embodiment of the present invention, which has an inverted U-shape having one nozzle 82. A riser pipe 85 is detachably connected to the nozzle pipe 83 by a riser flange joint 84.

Further, a throat 87 integrally connecting a bell mouth 86 facing the nozzle 82 is detachably connected to a diffuser 89 having a truncated cone shape by a throat flange joint 88.

That is, the nozzle 82 for ejecting high-pressure drive water
Since the nozzle pipe 83 having the above and the bell mouth 86 which receives the jet of high pressure driving water from the nozzle 82 are worn away, these 83 and 86 are detachably attached by the respective flange joints 84 and 88, so that they can be appropriately exchanged for a replacement. You can

The nozzle tube 83 is formed in an inverted U-shape by bending the first bent portion 90 and the second bent portion 91 of the nozzle 82 on the upstream side of the driving water by approximately 90 ° on the same plane. The downstream end portion (upper end portion in FIG. 13) of the riser pipe 85 is bent in a direction perpendicular to a bending plane including the central axes of the first and second bending portions 90 and 91 to form a third bending portion 92.
To form a second bent portion 91 to a third bent portion 92.
Up to about 10 times the inner diameter r of the riser pipe 85 (10
It is formed within r) and is shorter than the length 20r of the conventional jet pump 1 shown in FIG.

That is, the first, second and third bent portions 90, 9
By bending three-dimensionally by 1, 92, that is, three-dimensionally, the high-pressure driven water is given a three-dimensional bend before flowing into the nozzle 82, and a swirl flow is given to the high-pressure driven water ejected from the nozzle 82. The swirling flow promotes suction and mixing of the driven water sucked from the bell mouth 86 into the bell mouth 86, facilitates and smoothly converts the momentum of the driving water Wa and the driven water Wb, and improves the efficiency of the jet pump. We are trying to improve.

Next, how the flow of the driving water Wa passing therethrough actually changes due to such pipe bending will be described based on the latest flow analysis by a computer.

First, the pipe 100 as shown in FIG.
From the inflow side in of the driving water toward the outflow side out, the first, second, third and fourth bent portions 101, 102, 103, 104
15 shows that the secondary flow distribution in the axial cross section of the observation section 105 on the outflow side out is calculated when the same is bent at approximately 90 ° on the same plane.
The results shown in are obtained. The small arrows in FIG. 15 indicate the flow direction of the secondary flow.

On the other hand, as shown in FIG.
From the inflow side in of the drive water to the outflow side out
When the bending portions 111 to 113 are three-dimensionally bent by approximately 90 °, the secondary flow in the axial cross section of the observation portion 114 on the outflow side out is distributed as shown by the small arrow in FIG. 17, and the swirling flow is generated. It turned out to be occurring.

That is, when the flow path of the driving water is three-dimensionally bent as shown in FIGS. 13 and 16, a swirling flow can be generated in the driving water, so that the driven water is sucked and the driving water is driven. Mixing of water and driven water can be promoted, and the momentum of driving water and driven water can be easily converted. As a result, the throat 87 can be made relatively short, so that the fluid resistance in the flow path wall can be reduced and the efficiency of the jet pump can be increased.

In the present embodiment, the second bending portion 91 of the jet pump 81 shown in FIG. 13 may be bent three-dimensionally with respect to the first and third bending portions 90 and 92. Nozzle tube 83 at the second bent portion 91 as shown in FIG.
May be bent three-dimensionally.

Furthermore, the third bent portion 92 in FIGS. 18 (a) and 18 (b) is not always necessary to give the swirling flow to the driving water Wa, and the first bent portion 90 and the second bent portion 9 are not necessary.
It is experimentally confirmed that the three-dimensional bending may be formed by only one, and the swirling flow can be given to the driving water also by this.

That is, from the first bent portion 90 to the riser pipe 8
By forming two or more three-dimensional bent portions within 10 times (10r) of the inner diameter r of 5, the swirling flow can be given to the driving water.

Further, in each of the above-mentioned embodiments, the case where the present invention is applied to the jet pump for sucking and increasing the pressure of the driven fluid has been described, but the present invention is not limited to this and, for example, steam is used. It can also be applied to a steam injector or the like that is ejected from a nozzle and sucks the second fluid by its condensation effect.

[0090]

As described above, in the first to ninth inventions of the present application, the driven fluid is accelerated in multiple stages in the axial direction by the driving fluid and is accelerated in different cross sections. It is possible to reduce the pressure loss, reduce or prevent cavitation, and improve the efficiency of the jet pump.

Further, in the second and third inventions of the present application, since the ejection angle of each outer peripheral side nozzle portion is inclined in the same direction in the circumferential direction of the suction port, ejection is performed from each outer peripheral side nozzle side to the suction port side. It is possible to generate a swirling flow in the driven fluid. Therefore, the driven fluid around the suction port can be smoothly sucked into the suction port, and the suction flow rate can be increased by reducing or preventing eddy loss and cavitation of the flow.
The efficiency of the jet pump can be increased.

Further, according to the fourth aspect of the present invention, since the saw-tooth notch is formed at the tip of each nozzle portion, the run-up section for contact between the driving fluid and the driven fluid is formed, and the abrupt contact is made. It is possible to prevent the occurrence of cavitation due to the acceleration of the driving fluid.

Furthermore, according to the seventh aspect of the present invention, since the area increase rate in the axial direction can be suppressed at the diffuser inlet portion where the flow velocity is high, the flow separation in the diffuser can be suppressed to the minimum.

Further, in the eighth invention of the present application, slight separation of the flow occurs at the diffuser inlet portion where the flow velocity is high, but the separation reattaches at the downstream portion, and this re-adhesion flow generally causes the separation of the flow. Since it hardly occurs, flow separation in the diffuser can be suppressed to a minimum.

Further, in the ninth invention of the present application, since the fins or grooves for generating the swirling flow are provided on the inner surface of at least one of the diffuser portion and the throat portion, the swirling flow is generated in the fluid to form the swirling flow. Fluid separation in the throat portion can be reduced or prevented, and the diffuser efficiency can be increased.

Furthermore, in the tenth to twelfth inventions of the present application, since the flow path is three-dimensionally bent on the upstream side of the nozzle portion of the jet pump, the driving fluid ejected from this nozzle toward the suction port is A swirling flow is generated. This swirling flow smoothly sucks the driven body around the suction port, increases the suction flow rate, promotes the mixing of the driving fluid and the driven fluid, and facilitates the exchange of the momentum of both fluids. , The efficiency of the jet pump can be increased.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing the overall configuration of an embodiment of a jet pump according to the present invention.

FIG. 2 is a plan view of a main part of the embodiment shown in FIG.

FIG. 3A is an enlarged view of a main part of FIG. 1, and FIG.
The enlarged view of the nozzle tip part of (a).

4A and 4B respectively show modified examples of the diffuser shown in FIG. 1, in which FIG. 4A is a conical diffuser, FIG. 4B is a trumpet diffuser, and FIG. 4C is a bell diffuser.

5A is a diagram illustrating the shape of the trumpet diffuser shown in FIG. 4B, FIG. 5B is a diagram showing the shape of the bell diffuser shown in FIG. 4C, and FIG. 6 is a graph showing a relative relationship between a swirl fin angle and a pressure loss coefficient in a conical diffuser.

FIG. 6 is a graph showing an M ratio-efficiency curve of the present example shown in FIG. 1 in comparison with that of a conventional example.

7A to 7C are plan views respectively showing modified examples of the multi-stage acceleration swirl drive water nozzle shown in FIG. 1.

FIG. 8A is a perspective view of an essential part of another embodiment of the present invention,
FIG. 6B is a perspective view of a main part of still another embodiment of the present invention.

FIG. 9 is a schematic vertical sectional view of another embodiment of the present invention.

10 (a) is an enlarged perspective view of the nozzle portion shown in FIG. 9,
(B) is a bottom view of the same figure (a).

11A is a bottom view of a modified example of the nozzle portion shown in FIG. 10, and FIG. 11B is a bottom view of still another modified example.

FIG. 12 is a graph showing the M ratio-efficiency curve of the example shown in FIG. 9 in comparison with that of the conventional example.

13A is a partially cutaway front view of another embodiment of the present invention, and FIG. 13B is a side view of FIG. 13A.

FIG. 14 is a perspective view of an example when the pipe is bent in a plane.

15 is a diagram showing a secondary flow distribution in the observation part of the pipe shown in FIG.

FIG. 16 is a perspective view of an example in which the pipe is bent three-dimensionally.

17 is a diagram showing the secondary flow distribution in the observation part of the pipe shown in FIG.

18A is a partially cutaway front view showing a modified example of the embodiment shown in FIG. 13, and FIG. 18B is a side view of FIG.

19 (a) is a partially cutaway front view of a conventional jet pump, and FIG. 19 (b) is a side view of FIG. 19 (a).

20 is a view showing the action of the jet pump of FIG.

FIG. 21 shows a conventional jet pump shown in FIG.
FIG. 3 is a diagram showing a system configuration of a recirculation circulation system and a water supply system when incorporated into the reactor recirculation system of FIG.

FIG. 22 is a graph showing an M ratio-efficiency curve of a conventional jet pump.

23 is a pressure distribution diagram of the conventional jet pump shown in FIG. 19 and the like.

FIG. 24 is a partially enlarged view of FIG. 23.

FIG. 25 is a velocity vector diagram of the conventional jet pump shown in FIG. 19 and the like.

26 is a partially enlarged view of FIG. 25.

FIG. 27 is an enlarged view of another part of FIG. 25.

[Explanation of symbols]

 31, 51, 61, 71, 81 Jet pump 32 Multi-stage acceleration swivel drive water nozzle 33 Swirling fin 34, 89 Diffuser 34a Conical diffuser 34b Wrapper type diffuser 34c Bell type diffuser 34o Discharge port 35, 86 Bell mouth 36 Central nozzle 37a- 37h Outer peripheral swivel nozzle 38a-38h Branch pipe 39,87 Throat 40 Notch 52 Upper stage bell mouth 53 Upper stage drive water nozzle 62 Extension part 72 Nozzle pedestal 83 Nozzle pipe 90 First bending part 91 Second bending part 92 Third bending part Wa drive Water Wb Driven water

Front page continuation (72) Wataru Mizumachi Inventor Wataru Mizumachi 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Inside the Toshiba Corporation Yokohama office (72) Inventor Akira Tanabe 8-Shin-Sugita-cho, Isogo-ku, Yokohama-shi, Kanagawa In the office

Claims (12)

[Claims] 1. A driving fluid is ejected from a nozzle to a suction port to suck in the driven fluid around the suction port, the driving fluid and the driven fluid are mixed at a throat portion, and pressure is increased at a diffuser portion. In a jet pump that discharges afterwards, the nozzle protrudes toward the suction port side on a concentric circle outside the central nozzle part and the central nozzle part that projects from the axial center part toward the suction port side. A jet pump, comprising: a plurality of outer peripheral side nozzle parts, each of which is shorter than the central side nozzle part. 2. The central nozzle unit has its ejection central axis aligned with the central axis of the throat unit, while each outer peripheral nozzle unit has its ejection angle at the required angle in the same direction in the circumferential direction of the suction port. The jet pump according to claim 1, wherein the jet pump is inclined. 3. The outer peripheral nozzle portions are arranged at equal pitches in the circumferential direction, and the ejection angles thereof are inclined at a required angle toward any one point on the central axis of the throat portion. The jet pump according to claim 1 or 2, which is characterized. 4. The central side nozzle portion and each outer peripheral side nozzle portion are
The jet pump according to any one of claims 1 to 3, characterized in that a serrated notch is formed at each of the tip ends thereof. 5. The cluster type structure according to claim 1, wherein the central side nozzle portion and each outer peripheral side nozzle portion are radially connected by a branch pipe to form a cluster type. Jet pump. 6. The jet pump according to claim 1, wherein the diffuser portion is formed in a truncated cone shape that widens in a truncated cone shape toward the fluid discharge port. . 7. The jet pump according to claim 1, wherein the diffuser portion is formed in a trumpet shape that expands in a trumpet shape toward the fluid discharge port. 8. The jet pump according to claim 1, wherein the diffuser portion is formed in a bell shape that expands in a bell shape toward the fluid discharge port. 9. The jet according to claim 1, wherein at least one of the diffuser portion and the throat portion is provided with fins or grooves for generating a swirling flow on an inner surface thereof. pump. 10. A driving fluid is ejected from a nozzle to a suction port to suck in the driven fluid around the suction port, the driving fluid and the driven fluid are mixed in a throat portion, and the pressure is increased in a diffuser portion. A jet pump which discharges afterwards, wherein the upstream flow path of the nozzle is three-dimensionally bent. 11. The fluid bending portion has at least three places, and the tube axial surface of the intermediate bending portion is perpendicular to the tube axial surfaces of the bending portions at both ends thereof. Item 10. The jet pump according to item 10. 12. The fluid bending part is provided in two places, and the tube axis surfaces of these bending parts are perpendicular to each other, and the length between these bending parts is set within 10 times the flow path diameter. The jet pump according to claim 10, characterized in that.