JPS62261790A - Pulsation preventing device for valve - Google Patents

Abstract

PURPOSE:To prevent the occurrence of pulsation, by a method wherein a flow uniformizing device is located to a flow passage part on the downstream side which is situated right subsequently to a valve body positioned against the flow direction of fluid. CONSTITUTION:A flow uniformizing device 14, formed with plural flow uniformizing plates 13 positioned in parallel at intervals of a proper distance, is situated to a flow passage part 12 on the downstream side which is situated right subsequently to valve bodies 10 and 11 positioned against the flow direction of fluid. This constitution enables the magnitude of an eddy current, generated right after the valve bodies 10 and 11, to be limited to a value equivalent to the distance between the uniformizing flow plates 13, resulting in the possibility to prevent the occurrence of pulsation due to location of the valve bodies 10 and 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a device for preventing the generation of pulsating flow due to a valve.

(Prior Art) When an object is present in a fluid flow, a vortex is generated in a flow path directly downstream of the object in the fluid flow direction. For example, when a Karman vortex 2 is generated behind the object 1 as shown in FIG. 5, each vortex shedding causes periodic fluctuations in the flow, which can cause pulsation. Moreover, the object 1 is also subjected to force every time the vortex is released, and if the object 1 has low rigidity, mechanical vibrations may also be induced.

Further, as shown in FIG. 6, even if the vortex 3 does not originally separate from the object 1a, the pressure decreases at the center of the vortex, and portex cavitation 3a may occur. When such cavitation 3a occurs, the vortex separates. After that, a vortex develops, and cavitation 3a
Peel off. That is, even in this case, pulsation may occur.

(Problems to be Solved by the Invention) The case shown in Fig. 5 above corresponds to a butterfly valve, and the case shown in Fig. 6 corresponds to a gate valve, but these conventional valves prevent the generation of vortices as described above. Since no consideration was given to this, there was a problem of pulsation occurring.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention prevents the generation of pulsating flow due to the vortices created by the valve body in the downstream flow path section immediately behind the valve body with respect to the fluid flow direction. Features (effects) characterized by the provision of a rectifier that acts to reduce or reduce pulsation. By providing a rectifier as described above in the downstream flow path immediately after the valve body, generation of large-scale vortices can be eliminated and pulsation can be reduced. Occurrence can be prevented.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings of FIGS. 1 to 4. Fig. 1 shows a pulsation prevention device for a butterfly valve having a rotating valve body 10, and Fig. 2 shows a pulsation prevention device for a gate valve having a slide valve body 11. A flow rectifier 14 consisting of a plurality of rectifying plates 13 arranged in parallel at appropriate intervals is provided in the downstream flow path 12 of the rectifying plate 13. It can be limited to about the interval. It is also necessary to take measures to prevent the formation of vortices behind the rectifier by making the flow velocity uniform from the rectifier 14. For this purpose, it is preferable to provide a large number of pressure equalizing holes 13a in the current plate 13. That is, the intention is to provide sufficient loss to the flow passing between the rectifying plates so that the flow is uniform and no large-scale vortices are generated in the rectifier 14.

The rectifier 14 may be constructed by combining plates 15 in a lattice shape as shown in FIG. 4(A), or may be constructed by bundling small diameter pipes 16 as shown in FIG. 4(B). In this case, if a pressure equalizing hole is required, a hole (not shown) may be provided in the plate material 15 or the pipe 16.

FIG. 3 shows a specific example in which a ball valve body 9 and a grid rectifier 14' are combined. This downstream flow path portion 12 is called a side flow path portion 12′.
A grid-shaped rectifier 14' is inserted and fixed at '.

(Effect of the invention) The pulsation prevention device of this invention has a
Since the rectifier as described above is provided, the occurrence of pulsation due to the valve can be prevented or reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing a pulsation prevention device for a butterfly valve according to a first embodiment of the present invention, and FIG. 2 is a sectional view of a main part showing a pulsation prevention device for a gate valve according to a second embodiment of the invention. Third
The figure is a sectional view of a main part showing a pulsation prevention device for a ball valve according to a third embodiment of the present invention, FIGS. 4A and 4B are configuration explanatory diagrams showing different embodiments of a rectifier, and FIGS. FIG. 6 is a conventional illustration showing that when an object is present in a fluid flow, a vortex is generated immediately after the object. 9, 10.11... Valve body, 12.12'... Downstream flow passage section immediately after the valve body, 14.14'... Rectifier.

Claims (1)

[Claims] A pulsation prevention device for a valve, characterized in that a rectifier for preventing or reducing the generation of pulsating flow due to a vortex created by the valve body is provided in a downstream flow path immediately after the valve body in the fluid flow direction.