JPS5916105B2 - liquid pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to prevent cavitation in a pump that pressurizes and pumps liquid stored in a saturated state, and to obtain a low NPSH (net effective suction head).

For example, if a pump pumps a liquid with a low boiling point such as liquid oxygen or liquid nitrogen, or a pump that pumps a liquid with a non-low boiling point, if it is installed and used in a high-temperature environment,
Part of the liquid in the suction pipes of these pumps is vaporized by external heat, resulting in a gas-liquid mixture.

This not only makes the suction efficiency of the pump extremely bad, but also causes it to become unable to pump liquid. Therefore, this type of pump is equipped with a gas removal chamber, and after removing the gas from the liquid, only the liquid can be removed. Normally, the gas is sent to the compression chamber.

This gas removal mechanism generally has a structure as shown in FIGS. 1 and 2, in which liquid is sent from the lower part of a storage tank 1 through a liquid feed pipe 2 and introduced into a gas removal chamber 4 through an inlet 3.

The gas removal chamber 4 is formed in an annular and horizontal shape around the outer periphery of the discharge valve 5 and the discharge pipe 6, and the gas in the suction liquid introduced into the chamber 4 rises by the floating blade and flows from the gas return lower to the gas return pipe. 8 and is returned to the gas layer section of the storage tank 1.

The liquid from which the gas has been separated in the gas removal chamber 4 passes through the liquid passage 9, pushes open the suction valve 10, is led to the compression chamber, increases the pressure by the operation of the piston 11, and is pumped out from the discharge valve 5 and the discharge pipe 6. .

As described above, the gas removal mechanism in conventional pumps, especially the gas removal chamber, is configured in a horizontal annular shape, and the liquid flows at right angles to the gas floating blades and reaches the suction valve, so separation is performed simply by the floating blades. There was a drawback that the gas floating in the removal chamber was easily inhaled, resulting in poor removal efficiency.

This causes problems such as causing cavitation in the pump and increasing NPSH.

The present invention improves such a gas removal mechanism,
The floating direction of the gas and the inflow direction of the suction liquid into the suction port are reversed, and the flow rate of the suction liquid after gas separation is controlled to be lower than the floating speed of the gas.

The details will be explained below with reference to FIGS. 3 and 4.

As in the case of FIG. 1, the liquid, which is heated by passing through the liquid sending pipe 2 from the lower part of the storage tank 1 and contains bubbles, is introduced into the gas removal chamber 21 through the suction port 3.

The gas removal chamber 21 is constituted by, for example, an outer cylinder 22 shaped like a narrow neck bottle, an outlet pipe 23 provided at the upper part of the outer cylinder 22, and an inner cylinder 24 provided inside the outer cylinder 22 with a gap. It communicates with the suction valve 10.

The liquid entering the gas removal chamber 21 from the suction port 3 first passes through the ascending passage 2 formed by the gap between the outer cylinder 22 and the inner cylinder 24.
During this time, the bubbles in the liquid are sufficiently accelerated by the floating blade and separated at the upper end of the inner cylinder 25, and then returned to the gas layer portion of the storage tank 1 through the outlet pipe 23.

On the other hand, the liquid from which the bubbles have been separated is transferred from the upper end of the inner cylinder 24 to the cylinder 2.
After the flow descends inside 4, the suction valve 1 communicates with the lower part.
0 is pushed open and sent to the compression chamber, where it is pressurized and pumped in the same manner as above.

In addition, it is preferable that the flow rate of the liquid descending inside the inner cylinder 24 is configured to be slower than the velocity of the bubbles rising in the rising passage 25, or the amount of liquid supplied is preferably controlled.
This prevents air bubbles passing through the tip of the inner cylinder 24 from being sucked into the liquid descending inside the inner cylinder 24.

Moreover, the liquid descending inside the inner cylinder 24 is not affected by external heat intrusion at all due to the above-described structure, so that only the liquid can be pressurized through the suction valve 10 without generating bubbles.

In the above embodiment, the gas removal chamber 21 is provided in the piston head and is integrated with the pump body, but this may be attached to the liquid suction port of the pump, for example.

Also, although the explanation has been made on the assumption that it has a double cylindrical shape, the shape is free.

As is clear from the above description, the liquid pump according to the present invention can completely remove air bubbles that are generated when liquid is sent from the storage tank to the pump, so it not only prevents cavitation but also improves NPSH compared to conventional pumps. It can be reduced to about 1/2 to 173.

In general, conventional pumps are correct when the amount of remaining liquid in the storage tank decreases.
Although regular operation becomes difficult, the pump of the present invention can greatly improve NPSH, so it is possible to increase the effective internal volume in the case of a storage tank with the same volume.

It also has the effect of making it possible to absorb liquid from a relatively small or low-pressure storage tank.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional liquid angle pump, Fig. 2 is an end view of Fig. 1 - ■, Fig. 3 is a sectional view of the pump of the present invention, and Fig. 4
The figure is an end view of Figure 3 fV-IV. 1 is a storage tank, 2 is a liquid feeding pipe, 3 is an inlet, 10 is a suction valve, 2
1 is a gas removal chamber, 22 is an outer cylinder, 24 is an inner cylinder, and 25 is a rising passage.

Claims (1)

[Scope of Claims] 1. A pump for pressurizing and pumping liquid, which includes an outer cylinder 22 having an inlet 3 on the lower side and a gas outlet pipe 23 on the upper side, and an appropriate height inside the outer cylinder 22. A gas removal chamber 21 is provided between the outer cylinder 22 via a rising passage 25 and an inner cylinder 24 communicating with the suction valve 10 at the lower part thereof, so that the suction liquid from the storage tank 1 can be removed. Air bubbles in the liquid are separated while rising through the ascending passage 25 from the suction port 3, and the liquid is lowered from the upper end of the inner cylinder 24 into the inner cylinder 24 to form the suction valve 1.
A liquid pump characterized in that liquid is sucked into a compression chamber from zero. 2. Connect the gas removal chamber 21 to the head of the pump body or the liquid feed pipe 2.
A liquid pump according to claim 1, which is provided in claim 1. 3. The liquid pump according to claim 1, wherein the gas removal chamber is configured such that the flow rate of liquid descending through the inner cylinder 24 is slower than the flow rate of bubbles ascending through the ascending passage 25.