JPH0221428Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a submerged motor pump configured to suck in and discharge only the upper liquid, which has a lower specific gravity, out of two liquids that do not mix with each other.

When two liquids that have different specific gravities and do not mix are stored in a tank and it is necessary to discharge and transfer only the upper liquid to the outside, for example, a cavity is formed in underground rock and this cavity is When storing liquefied petroleum gas (LPG), crude oil, etc. in the cavity using the shell as a tank, the lower side is water and the upper side is liquefied petroleum gas, crude oil, etc. In such a case, the conventional submerged motor pump could not completely discharge and transfer the liquid located on the upper side.

The reason for this will be explained with reference to FIG. Liquefied petroleum gas, crude oil, etc. (hereinafter simply referred to as liquefied gas, etc.) are stored in a cavity 2 formed in an underground bedrock 1. Water 4 with a high specific gravity is always present. On the other hand, in the submerged motor pump 10, a motor section 11 and a pump section 12 (which may have multiple stages) are directly connected,
A suction port 13 is provided below it, and the entire device is configured to be able to operate in liquid. In order to discharge only the liquefied gas 3 to the outside with such a submerged motor pump 10, the suction port 13 is
must be located in the liquefied gas above the water, as shown. By the way, since the inside of the cavity 2 is maintained at the saturated vapor pressure of the liquefied gas, the effective suction head at the suction port 13 of the pump is determined by the liquid height from the suction port 13 of the liquefied gas, that is, the suction head H. . Also pump 10
The required head H is determined depending on the size and shape of the suction head, and the effective suction head is positioned and held so that it is larger than the required head H in order to prevent cavitation. Therefore, when sucking up liquefied gas with such a pump device, liquefied gas corresponding to the required suction head portion H must remain in the cavity 2.

Furthermore, as described above, if the pump 10 is pulled outside for repair or inspection while liquefied gas remains, a large amount of the liquefied gas will vaporize at atmospheric pressure, which is extremely dangerous.

The technique of providing a bottomed can with an open upper part on the outside of a directly connected pump motor was developed, for example, in the 1970s.
- Shown in Publication No. 19974. however,
The above-mentioned known techniques are intended to prevent the submersible pump from being filled with earth and sand. It does not maintain the necessary suction head, but the suction inlet is located at an appropriate location.

Furthermore, for example, Japanese Patent Application Laid-Open No. 52-81705 discloses a drain pump that does not cause cavitation when discharging liquid from a high vacuum tank.
However, in this known technique, since the liquid in the lower part of the tank is discharged, it is not possible to suction the liquid having a lower specific gravity located above the two liquids having an interface without mixing with each other.

Therefore, an object of the present invention is to provide a submerged motor pump that can substantially completely discharge only the upper liquid of two liquids that do not mix with each other.

According to the present invention, the device includes a pump part and a motor part, is arranged in a tank in which two liquids that do not mix with each other are stored, and is configured to suck and discharge the liquid located at the upper side of the two liquids. In the submerged motor pump, a bottomed cylindrical can whose upper part is open into the tank is provided at intervals on the outer periphery of the pump part and the motor part, and the pump suction port provided in the cylindrical can and The axial length of the upper open opening is longer than the necessary suction head of the pump.

Therefore, the cylindrical can is placed close to the boundary layer of the liquid, which is stored in two layers without mixing with each other, so that the opening of the cylindrical can is located slightly above the boundary layer. If the container is submerged in the tank, only the upper liquid will flow into the cylindrical can and accumulate in the bottomed cylindrical can. When the motor is started, the liquid in the cylindrical can is sucked by the pump, but since the axial length of the cylindrical can is long, there is no need for cavitation. As described above, according to the present invention, by locating the opening at the interface, it is possible to essentially suck only the upper liquid in the two liquids.

When implementing the present invention, the motor section and the pump section may be positioned in either the vertical direction. When the motor section is installed below the pump section, the suction port of the pump may be located above the motor section.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

The submerged motor pump 20 has three stages of pump sections 21, and the lowest pump section 21 is provided with a suction port 22 with a strainer. The motor section 23 is located above the pump section 21, and the motor section 23 and the pump section 21 are connected in series. Note that 24 indicates a discharge pipe.

On the outer periphery of the pump part, a bottomed cylindrical can 25 is provided with a plurality of ribs 26, 2 at intervals in the radial direction.
It is attached by...6. That is, the ribs 26, 26 fixed to the flange 27 of the can 25
...The other end is attached to the flange 28 of the motor section 23 by fixing means such as bolts and nuts. Further, the length L of the can 25 is longer than the required suction head H. i.e. Kyan 25
The length H between the upper opening O and the suction port 22 is such that a sufficient suction head can be maintained.

Therefore, the submerged motor pump 20
operates in such a way that the flange 27 on the upper edge of the can 25 is located near the boundary layer between the liquefied gas 3 and the water 4, as shown in FIG. Then, the length L of the can 25 is longer than the required suction head H, and a sufficient suction head is obtained, so that the liquefied gas 3 can be completely discharged to the outside. Therefore, there is no gas in cavity 2,
There is no danger in raising the pump 20 to the ground after the remaining gas is replaced with an inert gas, for example, to bring it to atmospheric conditions.

As described above, according to the present invention, a bottomed cylindrical can having an opening O at the top is installed astride the pump section or the motor section, and is configured such that its length is longer than the required suction head. Therefore, only the liquid located above the two liquids can be completely extracted to the outside.

[Brief explanation of the drawing]

FIG. 1 is a side view of a conventional submerged motor pump, FIG. 2 is a side view showing one embodiment of the submerged motor pump according to the present invention, and FIG. 3 is a view taken along the arrow in FIG. 20... Submerged motor pump, 21...
Pump part, 22... Suction port, 23... Motor part,
25...can, 26...rib, L...can length, H...required suction head.

Claims (1)

[Scope of utility model registration request] A submerged motor pump comprising a pump part and a motor part, arranged in a tank storing two liquids that do not mix with each other, and configured to suck and discharge the liquid located at the upper side of the two liquids, A bottomed cylindrical can whose upper part is open into the tank is provided at intervals on the outer periphery of the pump part and the motor part, and a pump suction port provided in the cylindrical can and an upper open opening are provided. Submerged motor pump characterized in that the axial length of the submerged motor pump is longer than the required suction head of the pump.