JPH0140650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for stirring a liquid containing a precipitate contained in a tank.

For example, in a clad slurry tank at a nuclear power plant, precipitates containing radioactive substances are periodically removed from the tank.

This operation is carried out by first stirring the liquid in the tank to suspend the sediment deposited at the bottom of the tank in the liquid, and then draining this liquid out of the tank.

This liquid stirring operation has conventionally been carried out as follows.

1 to 6 are schematic diagrams of a conventional stirring device for a liquid 2 contained in a tank 1.

In the apparatus shown in FIG. 1, a motor and a speed reducer (not shown) are installed above a tank 1, and a screw-shaped blade 3 is rotated to agitate the liquid 2.

This device is generally used in small tanks, but if continuous operation is required, maintenance of the rotating support bearings and decelerators is problematic. Further, it is necessary to extend a thick shaft through a shielding plate that shields the tank 1.

The apparatus shown in FIG. 2 uses an underwater motor 4, but a mechanism for suspending or suspending the motor is required. Moreover, decontamination work and maintenance of underwater motors are complicated.

The device shown in FIG.
The liquid 2 is returned from the tank 1 to the tank 1 for stirring. This device has problems such as blockage of the drain pipe 5, accumulation of radioactivity in the pump 6, and maintenance of valves and the like.

The device shown in Figure 4 blows air into the liquid 2 from a number of pipes 8 connected above.This device has no moving parts, makes it easy to stop and start stirring, and can be operated continuously. Although there are many advantages such as the following, there is a disadvantage that stirring cannot be done uniformly within the tank.

There is also a method in which fresh water is injected instead of air using this device, but this method still has the disadvantage that stirring is not sufficient and the liquid is diluted and increases in volume.

The device shown in FIG. 5 has a cone-shaped bottom of the tank 1 and blows air into the deepest part from a pipe 9, and the stirring effect is extremely good. However, the drawback is that the air rises in a concentrated manner, causing droplets to fly and contaminating the air above the tank.

In addition, as in the device shown in FIG.
If a large number of nozzles 11 are attached to the nozzle 11 with their tips pointing in the same rotational direction, the liquid can be moved in a circumferential direction by blowing air into the nozzle, but the liquid may enter the nozzle 11 or the annular tube body 10 when stopped. This may cause sediment to be carried inside the nozzle and clog the nozzle. This maintenance is also complicated.

As described above, each of the conventional stirring devices has the above-mentioned drawbacks, and there has been a desire to develop a device that provides sufficient stirring and is easy to maintain.

The present invention has been made with attention to the above points.

The details of the present invention will be explained below with reference to the drawings.

FIG. 7 is a schematic diagram of an embodiment of the apparatus of the present invention.
In this figure, a liquid 2 contained in a tank 1
Two or more (six in the figure) pipes 1 extend from above the liquid level 12 to near the tank bottom 13.
4 (downcomers) are arranged in a ring shape.

The upper end of each pipe 14 is connected to a header 15 made of an annular cylinder. Further, near the lower end of each pipe 14, there is provided a nozzle device 1 whose tip is directed in the same tangential direction of the ring within a substantially horizontal plane.
6 is provided.

On the other hand, a drain pipe 17 for discharging the liquid 2 is provided at the center of the tank bottom surface 13 of the tank 1 . Further, a pump device 18 is connected to the header 15 to feed air or fresh water thereto.

A detailed vertical cross-sectional view of the nozzle device 16 is shown in FIG. 9, and FIG. 10 shows a pipe 1 near the bottom of the tank.
Fig. 11 shows a vertical cross-sectional view of the mechanism around 4.
- A sectional view is shown.

In FIG. 9, the pipe 14 has an opening 19 at its lower end.
The side wall of the pipe 14 has a nozzle 20 extending laterally from near the lower end, and a nozzle 20 extending laterally from near the lower end.
A substantially cylindrical eductor 21 surrounding the vicinity of the tip of the eductor 21
is provided.

Further, on the side wall of the pipe 14, tenth and eleventh
As shown in the figure, a guide shoe 22 is attached, and this guide shoe 22 slidably grips a guide rail 23 attached vertically to the inner wall of the tank 1, so that each pipe 14 can move the header 15 up and down. Therefore, it can be moved up and down within the tank.

The above device operates as follows.

First, to the header 15 that has been pulled upwards,
When the pipe 14 is gradually lowered downward while sending air from the pump device 18, the pipe 14 is lowered along the guide rail 23.

As shown in FIG.
The air ejected from this opening blows away the debris and continues to descend until it abuts and engages the needle 25 provided near the bottom of the tank.

The needles 25 have a substantially conical shape with their pointed ends facing upward, and one needle 25 is disposed at a position where it engages with the opening 19 of each pipe 14.

Then, the opening 19 of the pipe 14 and the needle 25
When the two are tightly engaged as shown in FIG. Start a circular motion.

At this time, the nozzle 20 and the eductor 21 are oriented in the same circumferential direction, that is, in the tangential direction of the circle connecting the pipes 14, or inwardly or outwardly by 10 degrees. Further, if the nozzle is oriented within the above range in the horizontal plane, the liquid can be smoothly moved around the circumference regardless of the amount of water or the distance of the nozzle from the tank bottom or water surface.

Even if the nozzle is deflected vertically within a range of around 12 degrees from the horizontal, there is no significant difference in effectiveness.
If there is an element in the tank that disturbs the water flow, the nozzle may be directed in an appropriate direction within the above range depending on its position.

In this way, when the liquid is continuously stirred by air for a long time, most of the sediment in the tank will collect in the center of the tank. This is extracted from the drain pipe 17 along with the liquid.

Next, if necessary, after the amount of liquid in the tank has decreased, the operating mode of the pump device 18 is switched to send clean water to the header 15, and the water jet is used to forcefully push away the sediment remaining at the bottom of the tank and completely remove it. Make sure to rinse the bottom of the tank.

As explained above, according to the apparatus of the present invention, liquid can be stirred effectively and simply, and the following effects can be obtained.

(a) Since stirring is mainly done by air, there is little dilution of the liquid and continuous operation can be performed for long periods of time.

(b) Since the lower end of the nozzle is open, there is less risk of nozzle clogging, and even if the nozzle becomes clogged, maintenance is easy.

(c) Since the nozzle position is close to the inner peripheral surface of the tank, the stirring effect is good, and the amount of air required for stirring is small, so radioactive contamination of the air can be minimized.

(d) Water and air can be supplied from the same pipe, and the equipment is simple and maintenance is easy.

(e) Since the liquid discharge hole of the tank is provided in the center of the tank, the circumferential movement of the liquid is not disturbed, and the effect of draining sediment is also good.

(f) Since the lower end of the pipe engages with the needle at the bottom of the tank, hard crud can be removed when the pipe descends, and nozzle clogging can be prevented. In addition, it is easy to engage with the needle, and after descending, the lower end can be completely closed, allowing air and water to be vigorously jetted out from the nozzle.

In the above embodiment, the liquid was discharged using a drain pipe connected to the center bottom of the tank, but it may be sucked using a pipe inserted from above the tank to the center of the tank bottom. Furthermore, if the bottom of the tank is made into a cone shape, the liquid draining effect will be further improved.

Furthermore, in the embodiment, an example has been described in which a plurality of pipes are moved up and down together with the header, but it goes without saying that the structure may be such that the pipes are moved up and down one by one.

[Brief explanation of drawings]

1 to 6 are schematic diagrams of a conventional stirring device, FIG. 7 is a schematic diagram of an embodiment of the device of the present invention, and FIG.
9 is a longitudinal sectional view of the nozzle device, FIG. 10 is a longitudinal sectional view of the mechanism near the bottom of the tank, and FIG. 11 is a sectional view taken along line A-A. 1...Tank, 2...Liquid, 12...Liquid level, 1
3... Tank bottom, 14... Pipe, 15... Header, 16... Nozzle device, 17... Drain pipe, 19... Opening, 20... Nozzle, 21...
Eductor, 25...needle.

Claims (1)

[Claims] 1. A plurality of pipes extending from above the level of the liquid contained in the tank to near the bottom of the tank are arranged in a ring shape, and the upper end of each pipe is connected to a header made of an annular cylinder. A nozzle device is provided near the lower end of each of the pipes, the tip of which is directed in the same tangential direction of the ring, and near the bottom of the tank, the tip of the nozzle device engages with an opening at the lower end of each of the pipes. A liquid stirring device characterized in that the same number of conical needles as the number of pipes are arranged, and each of the pipes is supported in a tank so as to be movable forward and backward relative to the needle. 2. The liquid stirring device according to claim 1, wherein the nozzle device comprises a nozzle extending laterally from the side wall of the pipe and a substantially cylindrical eductor surrounding the vicinity of the nozzle tip.