JPS598431Y2 - Submersible motor pre-cooling water supply system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a submersible motor for driving a pump that is installed in a liquid feeding line of a boiler in a steam power station, for example, to send hot water, and particularly to a pre-cooling water supply device for the submersible motor.

First, an overview of the above-mentioned underwater motor will be explained with reference to FIG.

In Fig. 1, 1 is a pump casing that houses a pump runner, 2 is a liquid feeding line for the pump, and 3 is a motor casing that houses a motor body that is directly connected to the pump runner. It is constructed as a completely enclosed casing whose interior spaces communicate with each other.

In addition, the motor body is designed with insulation performance that allows it to operate underwater, and by filling the motor casing 3 with water, the shaft sealing mechanism of the pump is simplified, and the motor casing 3 is installed outside the machine. A cooling water circulation line 5 is pipe-connected via an installed ice cooler 4, and the motor body is cooled using water sealed in the motor casing 3 as a cooling medium.

Note that the circulation of cooling water is performed by an impeller installed on the motor shaft.

Meanwhile, during operation of the underwater motor, the cooling water circulation line 5,
For example, if a failure occurs in the water cooler 4, cooling of the motor body becomes insufficient and the temperature of the motor body increases.

In particular, when hot water at several hundred degrees Celsius is sent to the pump fluid line 2, a large amount of heat enters into the motor casing 3 from the hot water flowing through the fluid feed line 2, so the motor body reaches the allowable temperature. If the temperature exceeds the temperature, the motor cannot continue to operate, and not only will the motor have to be stopped in the ice, but there is also a risk that the motor may be exposed to dangerous conditions due to temperature.

In addition, stopping the pump in the liquid feed line 2 for a long time will impede the operation of the steam power plant.

As a countermeasure against this problem, in the past, a preliminary cooling water source 6 was installed for the submersible motor in addition to the above-mentioned cooling water circulation line 5 in case of an emergency.
In order to supply cleaner cooling water to the motor casing 3 and flow through it, a water filling valve 7 and a water supply pump 8 are inserted on the water filling pipe side, and a drain valve 9 is inserted on the drain pipe side downstream of the motor casing 3. Pre-cooling water supply line 10 via
A method is implemented in which the motor is connected to the motor casing 3 by piping.

Here, the water filling valve 7 and the drain valve 9 are, for example, electric on-off valves, and are operated together with the water supply pump 8 based on instructions from the controller 11.

The controller 11 also includes a temperature detection sensor 1 provided in the ice motor.
It is linked to operate in response to the output value of 2.

During normal operation, the preliminary cooling water supply line 10 is in a rest state with both the water filling valve 7 and the drain valve 9 closed.

If the temperature of the submersible motor rises abnormally due to a failure of the cooling water circulation line 5, etc., this abnormal temperature rise is detected by the temperature detection sensor 12, and the submersible motor immediately trips and temporarily stops operating.

At the same time, the water filling valve 7 and the drain valve 9 are opened via the controller 11, and as the water supply pump 8 is started, preliminary cooling water is fed through into the motor casing 3.

Therefore, the temperature of the motor body can be lowered while suppressing the influence of heat entering from the pump side of the liquid feeding line 2, and the motor can be restarted.

During this time, repairs will be made to the damaged areas.

By the way, when supplying preliminary cooling water to the motor casing 3 from the preliminary cooling water supply line 10, if the valve opening speed and valve opening degree of the water filling valve 7 and the drain valve 9 are not matched properly, the filling may be interrupted. The amount of drain discharged through the drain valve 9 may be larger than the amount of water flowing into the motor casing 3 through the water valve 7. There is a risk that hot water at a higher temperature may enter the motor casing 3.

Moreover, it is actually extremely difficult to properly match the valve opening speed and valve opening degree between the water filling valve 7 and the drain valve 9, due to the problem of control accuracy.

This invention was developed in consideration of the above points, and by fixedly additionally installing an extremely simple throttle part, the drain amount of the preliminary cooling water supply line is throttled, and the timing of opening the water filling valve and the drain valve is matched. A highly safe and reliable pre-cooling water supply device that can pressurize and fill pre-cooling water while reliably preventing hot water from the liquid supply line from entering the motor casing from the pump side, regardless of the The purpose is to obtain.

According to the present invention, this object is achieved by inserting an orifice into the drain side pipe of the pre-cooling water supply line.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, the preliminary cooling water supply line 1 according to the present invention is
An orifice 13 is inserted in the middle of the drainage pipe downstream of the motor casing 3 at 0.

The orifice 13 is, for example, an in-pipe orifice with a simple structure, and as shown in FIG. 2, the orifice 13 is inserted and installed in the middle of a drain pipe 14, which is a drainage side conduit, by connecting it with a flange.

Here, the cross-sectional area of the opening of the orifice is selected to an appropriate value so that d<D, where D is the drain pipe diameter and d is the opening diameter of the orifice.

In the above structure, when the temperature of the submersible motor rises due to a failure of the cooling water circulation line 5 and causes the motor to trip, the water filling valve 7 and the drain valve 9 are simultaneously opened as in the conventional case, and the water supply pump 8 is used as a backup. Cooling water is supplied to the motor casing 3.

However, since the orifice 13 is installed in advance on the drain pipe side, the flow rate of drain flowing out from the motor casing 3 is throttled by the orifice 13 even if the opening degrees of the water filling valve 7 and the drain valve 9 are the same. This will result in a limited flow of water.

Therefore, make sure that the pressure on the water filling pipe side of the preliminary cooling water supply line 10, that is, the discharge pressure P2 of the water supply pump 8, is higher than the water pressure inside the motor casing 3, which is determined from the pressure P1 of the liquid supply line 2. With this, it is possible to reliably fill the motor casing with pre-cooling water under pressure.

As a result, the water pressure inside the motor casing based on the pre-cooling water flowing through the motor casing 3 is maintained at a predetermined value or higher, and a portion of the pre-cooling water may slightly flow out toward the liquid feed line 2. Also, it is possible to reliably prevent hot water from entering the motor casing 3 from the liquid feed line 2 and endangering the motor.

However, the orifice 13 is a fixed throttle mechanism, and by setting its opening area appropriately in advance, the drain flow rate can always be kept in a constant relative relationship according to the amount of water supplied from the water filling side. In addition to its ability to limit current, it is extremely inexpensive.

As described above, according to the present invention, by inserting an orifice with a simple structure into the drain pipe side of the pre-cooling water supply line, it is possible to adjust the opening degree between the fill valve and the drain valve in an emergency. An effective pre-cooling water supply device can be obtained that can skillfully pressurize and fill the motor casing with pre-cooling water while reliably preventing hot water from entering from the liquid feeding line.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cooling water piping system diagram of an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the main parts in FIG. 1. 1... Pump casing, 3... Motor casing, 4... Water cooler, 5... Cooling water circulation line, 6...
...Preliminary cooling water source, 7.. Filling valve, 9.. Drain valve, 10.. Preliminary cooling water supply line, 13.. Orifice.

Claims (1)

[Scope of utility model registration request] It is equipped with a completely enclosed motor casing that is connected to the pump casing, and has a cooling water circulation line that circulates the cooling water filled in the motor casing through a water cooler installed outside the machine, as well as a water fill valve and a drain valve. In a submersible motor in which a preliminary cooling water supply line is connected to the motor casing in order to supply cooling water from a preliminary cooling water source into the motor casing in an emergency, the preliminary cooling water is connected to the drain side pipe of the preliminary cooling water supply line. A preliminary cooling water supply device for a submersible motor, characterized in that an orifice is inserted and installed to throttle the drain flow rate.