JPS58144689A - Multistage pump - Google Patents

Abstract

PURPOSE:To reduce the size, weight as well as cost of a pump, rectify a stream therein and exclude the affection of turbulent water by a method wherein multiple stages and difusers of a feed water pump for a boiler or the like are connected integrally by penetrating clamping bolts to form an inner casing. CONSTITUTION:Water, sucked from a suction port 11 by a first stage vane wheel 5A rotating together with a rotary shaft 6, is discharged from the vane wheel 5A, subsequently, is flowed into the disfuser 3A and increased in the pressure thereof, thereafter, is introduced into the next stage vane wheel 5B through a return path 8A having a water reflecting vane 7A. Thereafter, pressurized high-pressure water is discharged finally from the discharging port 12 after repeating the same operations. The vanes 3a of each difusers 3 are formed so as to have a configuration, in which the areas thereof are increased smoothly from the inlet to the outlet, in order to recover a velocity component, given to a fluid by each vane wheels 5, into a pressure component, and the area of flow path is formed so as to be small by increasing the thickness of the difuser vane 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to multi-stage pumps, particularly ring-shaped and barrel-shaped multi-stage tubes, such as boiler feed pumps.

It is well known that conventional multistage pumps include a stile, a ring-shaped multistage pump shown in FIG. 1, and a barrel-type multistage pump shown in the WJZ diagram. In the former ring-shaped multistage pump, an arbitrary number of stages 2 and diffusers 3 are combined, and they are integrally connected by a flange portion 14 provided on both sides and a tightening bolt 4 provided on the outside of the stage 2 to form a casing. Because of the 1t configuration, the bo/p has a disadvantage that its outer diameter becomes large and the size becomes large.

In addition, in the latter barrel type pump, an arbitrary number of combinations of stage 2 and diffuser 3't are attached to flanges provided on the outer periphery of stages 2a and 2b on both sides, and these are integrally connected by tightening bolts 4. Inner casing 1't-
The inner casing l is housed within the outer casing 15.

Since high discharge pressure is acting on the outer periphery of the inner casing l, compressive stress is generated in the stage 2, and even if the pressure inside the inner casing in the subsequent stage becomes high,
Since the pressure is smaller than the pressure at the outer periphery of the stage, it is possible to reduce the thickness of the stage 2.

However, since the tightening bolt 4 is provided on the outer periphery of the stage 2, the outer diameter of the inner casing 1 becomes large. Further, the wall thickness of the outer casing 15 is generally determined from the inner diameter of the outer casing 15 and the allowable stress, and can be determined by calculating the strength using the formula for a thick-walled cylinder. However, the influence of the inner diameter of the outer casing 15 is large, and the outer diameter of the pump becomes large in the conventional structure, so it is necessary to downsize the pump.
Moreover, it is difficult to reduce the weight, and the cost is high.

The present invention aims to eliminate the above-mentioned drawbacks.
In a multi-stage pump equipped with a casing made up of a combination of an arbitrary number of stages and diffusers, the stage and diffuser are penetrated by a tightening bolt, and the stage and diffuser are integrally connected by the tightening bolt to form a casing. It is characterized by:

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 3, reference numeral 1 denotes an inner casing, and this inner casing 1 is constructed by combining an arbitrary number of stages 2 and differential users 3, which are both integrally connected by 2.3'ji-tightening bolts 4. That is, the tightening bolt 4 passes through a bolt hole 1o provided in the diffuser blade 3a of the impeller and a bolt hole (not shown) provided in the stage 2 corresponding to this bolt hole 10, as shown in FIG. It is set up like this. 5 is an arbitrary number of impellers attached to the rotating shaft 6 and housed in the inner casing 1; 7 is a return flow path 8 formed between the diffuser 3 of each stage and the impeller 5 of the next stage; , water return vanes 9 provided on the downstream side of the tightening bolts 4 passing through the return passage 8; Casing, 13 is outer casing 9
This is a cover attached to the

The present embodiment has the above-mentioned configuration, and the water sucked in from the suction port 11 is discharged from the first stage impeller 5A that rotates together with the rotating shaft 6, and then flows into the diffuser 3A. After the pressure is increased by
It is introduced into the next-stage impeller 5B through a return passage 8Al having A. Since the same action is repeated thereafter, high-pressure water is finally discharged from the discharge port 12.

In order to recover the velocity component provided to the fluid by each impeller 5 into a pressure component, the blades 3ati of each of the diffusers 3 are formed in a shape that gradually increases in area from the inlet to the outlet, as shown in FIG. Since the flow rate is small in a pump with a low specific speed, the flow path area is formed to be small by increasing the thickness of the diffuser blade 3a.

The effects of this embodiment, which is arranged between stations, will be described in detail with reference to Figure 5. The broken lines in FIG. 5 indicate the corresponding portions of a conventional barrel-type multistage pump.

Since the inner casing 1 is constructed by combining an arbitrary number of stages 2 and diffusers 3, passing the tightening bolts 4 through them, and joining them together, it is necessary to attach the tightening bolts 4 to the outer periphery of the stage 2. There is no need to provide a flange surface or make the stage wall thicker than necessary. Therefore, it is possible to reduce the inner and outer diameters of the inner and outer casings 1.9, and to make the bob smaller and lighter, resulting in cost reduction 1i.

■ Since the water return blade 7 is provided in the return flow path 8 of each stage on the downstream side of the tightening bolt 4 that passes through the return flow path 8, the flow can be rectified, so that the return flow path can be tightened. It is possible to eliminate the effects of turbulent water caused by penetrating the bolt.

(Q: It is possible to create a structure where the ring-shaped multistage pump can be used as the inner casing of a barrel-type multistage pump, so it is possible to change the ring-shaped multistage pump to a barrel type that is easier to assemble and disassemble. Can be manufactured into multi-stage pumps containing interchangeability.

[Brief explanation of the drawing]

1 and 2 are longitudinal cross-sectional views of conventional ring-shaped and barrel-type multistage pumps, respectively; FIG. 3 is a longitudinal cross-sectional view showing an embodiment of the multistage pump (barrel type) of the present invention; and FIG. Fig. 3 is a front view of the diffuser of Fig. 3), and Fig. 5 is a vertical sectional view comparing the embodiment of Fig. 3 with the conventional example (Fig. 2). 1...Same casing, 2...Stage, 3...Diffuser, 4...Tightening bolt.

Claims (1)

[Claims] A multi-stage pump comprising a casing formed by combining an arbitrary number of stages and diffusers, characterized in that a tightening bolt is passed through the stage and the diffuser, and the stage and diffuser are integrally connected by the tightening bolt to form the casing. Multi-stage pump.