JPS58117400A - Jet pump - Google Patents

Abstract

PURPOSE:To enable to prevent sticking of powder particles to the wall surface of a suction chamber, by forming the suction chamber with a rigid porous material, and developing an air flow directed toward the inside of the suction chamber through pores formed in the porous material. CONSTITUTION:A suction chamber defining member 10, made of a porous material having pores the diameters of which are smaller than the minimum diameter of particles contained in a liquid to be conveyed, is disposed in the manner of surrounding a nozzle 1 concentrically with each other. The suction chamber defining member 10 defines therein a suction chamber 9 which consists of a cylindrical section 9a and a tapered section 9a having a diameter reduced gradually toward its top. In pump operation of the apparatus, a small amount of air is drawn into the suction chamber 9 via a pipe 13, a hollow space 12 and pores of the member 10 by the function negative pressure developed in the suction chamber 9. Therefore, sticking and accumulation of powder particles on the inner wall surface of the suction chamber 9 can be prevented by the air ejected into the chamber 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to jet pumps, particularly jet pumps used for transporting liquids containing powder.

[Technical background of the invention]

Jet pumps are widely used in chemical industry plants and the like because they do not have any moving parts, so there is no mechanical failure, and the equipment costs are low. %, the process fluid in nuclear fuel reprocessing plants contains extremely high radioactivity, and the pumps that handle it are also contaminated with radioactivity, requiring remote repair in the event of a breakdown. Therefore, in nuclear fuel reprocessing plants, jet pumps that are free from mechanical failure play an important role in transporting process liquids.

An example of a conventional jet pump will be described below with reference to FIG. That is, in Figure 1,
A suction chamber 2 that concentrically surrounds the nozzle 1 and has a cylindrical portion 2a and a tapered portion 2b connected to the cylindrical portion 2a, and a suction pipe 3 that connects to the cylindrical portion 2a of the suction chamber 2.
A jet pump is constituted by a throat 4 having a straight pipe 4a connected to the tip of the tapered part 2b and a diffuser part 4b connected to the straight pipe 4a which is tapered to spread light. A pipe 5 for supplying high-pressure superheated steam is connected to the nozzle 1, a pipe 6 leading to a source of liquid to be transported is connected to the suction pipe 3, and a transport pipe 7 is connected to the outlet of the throat 4.

The high-pressure superheated steam supplied from the pipe 5 is accelerated by the nozzle 1 and ejected into the suction chamber 2 at high speed.

As a result, the inside of the suction chamber 2 is brought into negative pressure, and the liquid to be transported is sucked into the suction chamber 2 via the piping 6 and the suction pipe 3. The injected superheated steam mixes with the liquid in the straight pipe portion 4a of the throat 4, condenses, and exchanges momentum. The mixed liquid of the condensed water and the liquid to be transported is decelerated and pressurized in the diffuser section 4b, and is discharged to the transport pipe 7.

[Problems with background technology]

When a liquid containing powder is transported using a jet pump having the above configuration, the powder adheres to the wall of the pump's suction chamber, etc.
Change the flow characteristics of the pump.

Due to adhesion and accumulation of the powder, the flow path of the pump may eventually be blocked. Therefore, when using a jet pump to transport liquids containing powder, it is necessary to periodically or irregularly remove the powder that has adhered to or accumulated on the pump. If the liquid is a process liquid in a nuclear fuel reprocessing plant, jet pumps that are resistant to powder adhesion are highly radioactive, so the jet pumps must be removed and cleaned by remote control. Removal of adhesion and accumulated powder requires a lot of effort and time.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to obtain a jet pump that can prevent powder from adhering to and depositing on the wall surface of a suction chamber.

[Summary of the invention]

In the present invention, the suction chamber, etc., where powder adheres and accumulates, is made of a rigid porous material, such as sintered stainless steel, with a pore diameter smaller than the minimum particle diameter of powder particles contained in the liquid to be transported. It is made of metal, ceramics, etc. as appropriate, and forms an air flow toward the interior of the suction chamber through the holes of the porous material, and achieves the above purpose by preventing powder particles from adhering to the air flow. .

[Embodiments of the invention]

Regarding Figure 2, in which the same parts as in Figure 1 are given the same reference numerals,
The details of one embodiment of the present invention will be explained. In FIG. 2, the nozzle 1 is concentrically opened at one end surface of a cylindrical suction chamber housing 8, and the throat portion 4 is opened at the other end surface of the housing 8. Inside the casing 8 is a suction chamber wall body that includes a suction chamber 9 made of a porous material whose pore diameter is smaller than the minimum particle diameter in the liquid to be transported and has a cylindrical portion 9a and a tapered portion 9b. 10 are installed concentrically surrounding the nozzle 1. Note that the end plate of the housing 8 on which the throat portion 4 is provided is provided with a tapered surface 11 that connects the tapered portion 9b of the suction chamber 9 and the straight pipe portion 4a of the throat portion 4. Furthermore, wall 1
0 is provided with a small diameter portion 10a between it and the inner peripheral surface of the housing 8,
An annular space 12 is formed, and this space 12 is connected to the pipe 1.
3 to the atmosphere or a source of pressurized air.

In the jet pump of the present invention having the above configuration, the state in which liquid is transported is the same as that in the conventional jet pump described with reference to FIG. 1, so a description thereof will be omitted.

Thus, while the jet pump is in operation, the piping 13 is kept in communication with the atmosphere. Then, due to the negative pressure in the suction chamber 9 during pump operation, a small amount of air is blown into the suction chamber 9 through the piping 13, the space 12, and the holes in the suction chamber wall 10, and this blown air causes the suction chamber 9 to Adhesion and accumulation of powder particles on the inner wall surface is prevented.

Further, when the operation is stopped, that is, when the supply of high-pressure superheated steam to the nozzle 1 is stopped, the piping 13 is connected to a pressure air source to scatter and remove residual powder particles.

Furthermore, if a valve with a variable opening degree is provided in the pipe 13, the amount of air blown out during jet pump operation can be set arbitrarily. Since the suction flow rate of the jet pump changes depending on the flow rate of air blown into the suction chamber, the suction flow rate can be arbitrarily set by adjusting the opening degree of the valve.

Note that since the inside of the suction chamber 9 is maintained at a negative pressure during operation of the jet pump, the liquid does not penetrate the suction chamber wall 8 and flow back into the pipe 13.

FIG. 3 shows a liquid transport system using the jet pump of the present invention having the above configuration. In this figure, the lower end of the pipe 6 connected to the suction pipe of the pump P of the present invention is immersed in the liquid 15 containing powder in the tank 14, and the transport pipe 7 is connected to the destination storage tank 16. It is communicated. Also, space 1
A flow rate regulating valve 1 is provided in the pipe 13 that communicates the flow rate regulating valve 1 with the atmosphere.
7 is provided, and this valve is controlled as follows. That is, the suction flow rate of the pump P is calculated by the calculator 19 from the output of the level meter 18 that detects the level of the tank 14, and the controller 20 adjusts the flow rate adjustment valve based on the difference between the calculated value and the preset suction flow rate. 17
Set the opening degree.

By doing as described above, in this transportation system, the suction flow rate of the jet pump P can be maintained at the set value at all times.

〔Effect of the invention〕

As is clear from the above, according to the present invention, adhesion and accumulation of powder particles to the jet pump can be prevented. It is no longer necessary to disassemble and clean highly radioactive pumps, which are used to transport process liquids in nuclear fuel reprocessing plants, as in the past, which takes a lot of effort and time. It is possible to improve the operating rate and improve the safety of workers.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional jet pump, FIG. 2 is a sectional view of an embodiment of the present invention, and FIG. 3 is a fluid circuit diagram of a liquid transport system constructed using the embodiment. 1゛・°nozzle, 3...suction pipe, 4...
Throat part, 8... Suction chamber housing, 9... Suction chamber, 10... Suction chamber wall, 12... Space,
13...Piping application agent Patent attorney Kikuchi Department 5 Figure 1 Figure 2

Claims (1)

[Claims] A nozzle is concentrically attached to one end surface, and a suction chamber is provided in a suction chamber housing which has a throat section concentrically attached to the other end surface, and which concentrically surrounds the nozzle at one end and communicates with the throat section at the other end. A space having an annular cross section is formed between the outer peripheral surface and the inner peripheral surface of the housing, a suction chamber wall made of a rigid porous material is housed therein, and the space is communicated with the atmosphere via piping. A jet pump characterized by: