JPH0454076B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a degassing device for a canned motor pump.

Generally, canned motor pumps are used as pumping equipment when shipping to tank trucks at LPG storage bases (high pressure and room temperature).This canned motor pump lubricates the pump motor bearings and cools the motor coil using its own liquid. There is something special about what you do.

By the way, when handling evaporative liquids such as LPG with a canned motor pump, when the motor stops, residual heat from the motor causes the liquid to gasify, resulting in poor lubrication and cooling of the pump and motor bearings.
Furthermore, when the pump is restarted, gas that has accumulated near the pump and motor is trapped, causing damage to the pump, motor bearings, and other parts. For this reason, in canned motor pumps that handle LPG, the pump impeller and pump motor bearings
The condition for starting the pump is that it is filled with LPG.

Therefore, the purpose of the present invention is to reliably detect the above conditions, and when gas is generated, immediately direct the gas to the exhaust gas line using a switching valve, thereby preventing damage to the pump, motor bearing, etc. In addition, the purpose is to automate the degassing operation and stop the pump when the tank truck is not shipped, thereby saving power and labor and making it compatible with the tank truck fixed quantity shipping control system.

An example of a conventionally configured degassing device is shown in FIG.
Pass through the air gap and bearing part of this
LPG is returned to the storage facility (spherical tank) 4 through a separately provided reverse line 3a. By the way, the reverse line was formed with a continuous ascending gradient without a pocket part (high and low part) 5 in the middle, as shown by the two-dot chain line 3b in FIG. 1, and the terminal end was connected to the upper gas layer 6 of the storage facility 4. Regardless of the case, when planning the expansion of this canned motor pump 1, or considering future tank expansion, etc.,
It is unavoidable that a pocket portion 5 is formed in the middle of the reverse line, and the terminal end of the reverse line may have to be connected to the bottom 7 side of the storage facility 4. In this case, when the canned motor pump 1 is stopped during operation, residual heat generated in the pump 1 and the motor 2 causes the LPG in the same part to gasify and expand, resulting in a phenomenon in which the liquid is pushed to the side of the piping where resistance is smaller. Therefore, although the inside of the pump is gasified, the liquid head pressure of the spherical tank does not have the force to push the gas to the river line, so the next time the pump is started, this generated gas is released to the outside (in this case Therefore, it is necessary to fill the canned motor pump 1 and motor 2 with LPG (which has no choice but to be released into the atmosphere), and manual degassing work is essential before operation.

For this reason, the canned motor pump is
When trying to support a tank truck shipping system, selective operation based on the number of tank trucks to be shipped is not possible and continuous operation is required, resulting in the problem of increased power loss due to minimum flow operation when not shipped.

However, if the canned motor pump is degassed manually, there is a problem in that it cannot be operated in conjunction with other systems. Therefore, as a mechanical degassing method, a gas pot 8 of the amount necessary to absorb the residual heat of the motor 2, etc. is installed above the pump outlet of the reverse line, and the gas generated when the pump is stopped is replaced with the liquid in the gas pot. It is also a useful method to

The present invention aims to provide an effective degassing device by providing means for reliably detecting these.

As shown in Fig. 2, the present invention includes an LPG liquid level detector 9 in the gas pot 8, which detects the upper and lower limits of the liquid level, and when the liquid level falls below the lower limit, the LPG liquid level detector 9 is installed on the reverse line. Then, an automatic switching valve (three-way switching valve) 10 installed at the branch point of the gas line and the liquid line is switched by a signal from the liquid level detector 9 using an appropriate means such as a solenoid valve, and the switch is switched to the gas line 11 side. Then, when the liquid level in the gas pot reaches the upper limit, switch to the liquid line 12 again using the same procedure as above. Check that the pump is filled with LPG.
Here, by providing a check valve 13 on the pump suction side, the flow of generated gas is forced into the reverse line 3.
It is possible to speed up the filling speed of LPG into the pump.

The control system prevents the pump from running dry by interlocking the pump so that it cannot operate during degassing. (If liquid gets into the gas line, the difference in height of the piping will cause the liquid to leak into the pocket.) It is necessary to prevent liquid from flowing in, as this will cause a buildup and prevent gas from being vented smoothly, causing trouble.)

The above sequence eliminates the need for manual degassing operations, and enables delivery control systems to tank trucks and automatic selective operation of canned motor pumps in process lines, which can be applied in a wide range of fields and contributes to power savings. That will happen.

In the figure, reference numeral 14 indicates a pump inlet pipe, 15 a pump outlet pipe, 16 a tank truck, and 17 a gas balance pipe.

The liquid level detector 9 of the present invention can also utilize various types of liquid level gauges and liquid level detectors. Further, for venting the gas in the gas pocket, either an automatic switching valve or a manual switching valve may be used depending on the usage state of the pump.

Therefore, according to the present invention, since the liquid level in the gas pot is accurately detected, degassing operations can be performed reliably, damage to pump bearings etc. can be prevented, gas is not released into the atmosphere, thus saving resources, and gas line Since liquid (LPG) does not get mixed in, there is no problem of gas line blockage, and when an automatic valve is installed, gas venting work is automatically detected and gas venting is performed automatically, reducing the capacity of the gas pot compared to conventional ones. It has excellent effects such as being able to

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional device, and FIG. 2 is a schematic diagram of the device of the present invention. DESCRIPTION OF SYMBOLS 1... Canned motor pump, 2... Motor, 3a, 3b... Reverse line, 4... Storage equipment, 5... Pocket part, 6... Upper gas layer, 7
... Bottom, 8 ... Gas pot, 9 ... Liquid level detector, 10 ... Automatic switching valve, 11 ... Gas line,
12...Liquid line, 13...Check valve.

Claims (1)

[Claims] 1. In a canned mode pump equipped with a reverse line, a gas pot with a liquid level detector built in is installed on the pump discharge side of the reverse line, and an automatic switching valve is installed on the reverse line beyond the gas pot installation position. and branching the reverse line beyond the automatic switching valve into a gas line and a liquid line, connecting the gas line to the upper gas layer of the storage equipment, and connecting the liquid line to the bottom side of the storage equipment,
The can, characterized in that the automatic switching valve is connected to selectively operate either the gas line or the liquid line in response to a signal from the liquid level detector, and a check valve is provided on the suction side of the pump. Gas venting device for motor pump.