JPH06323295A - Method for cooling down and hotting up pump for low temperature liquid - Google Patents

Abstract

PURPOSE:To cool down a pump accurately and rapidly by measuring a change in a resistance value of a winding of a pump driving motor during the operation of cooling-down to adjust an injection liquid flow of cooling-down low temperature liquid so that the rate of the change is less than the threshold rate of the change. CONSTITUTION:A pump for low temperature liquid is provided with a pump driving motor 8 cooled by low temperature liquid to be poured. The pump driving motor 8 is disposed on the upper part of a submergible pump body 9 in a pump container 1. Then, in cooling down by low temperature liquid, the low temperature liquid is supplied from a piping T through a drain pipe 12 to the pump container 1. The poured liquid flow or poured liquid flow speed of the low temperature liquid is set to be less than the threshold cooling speed or threshold rate of temperature reduction. Also, gas in the pump container 1 is blown off from a vent 4. Further, after the passage of a predetermined time, a controlling valve V7 is closed to stop liquid poured from the drain pipe 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature liquid used in a power generation facility using a low temperature liquid such as LNG (liquefied natural gas) or LPG (liquefied propane gas) as a fuel, a storage facility and a vaporization facility for LNG and LPG. The present invention relates to a cool-down method and a hot-up method for a low-temperature liquid pump such as a low-temperature liquid submerged pump used to boost the pressure of the low temperature liquid.

[0002]

2. Description of the Related Art FIG. 5 shows the Japan Society of Mechanical Engineers Showa 6
19th of "Mechanical Engineering Handbook-Engineering Edition-C7 Energy Equipment / System" published on December 15, 3rd
It is sectional drawing of the typical well-known submerged pump for low temperature liquids as a low temperature liquid pump shown on page 9. As shown in FIG. Note that, in this figure, hatching showing a cross section is omitted as in the original drawing, and arrows showing vents and flow paths not shown in the original drawing are added. In this figure, 1 is a pump container called a pot, and the pump container 1 is composed of a bottomed cylindrical container body 101 and a lid body 102 fixed to an open end of the container body 101. The lid 102 has
A discharge port 2 and a flow path 301 communicating with the discharge port 2 are provided. The lid 102 guides the vent 4 used for discharging gas from the pump container 1 and supplying temperature-rising gas at the time of hot-up, and the electric wire 6 for supplying electric power to the pump driving motor 8. A conduit tube 5 is provided. A connection pipe 7 is fixed to the electric wire pipe 5. Lid 10
One end of a motor case 802 that houses a motor main body 801 of the pump driving motor 8 that is a wound-type three-phase induction motor is fixed to the lower portion of 2. Motor case 802
Is composed of an outer cylindrical body 803, an inner cylindrical body 804, and a connecting member 805 that connects the both cylindrical bodies and forms a cylindrical flow path 302 between the both cylindrical bodies. The flow channel 302 communicates with the flow channel 301 provided on the lid body 102. The motor body 801 is
It is composed of a stator 806 fixed to the inner cylindrical body 804 and a rotor 807 arranged inside the stator 806. The stator 806 includes a core 806a formed by stacking silicon steel plates, and three-phase windings 806b respectively wound around salient pole portions provided at a predetermined circumferential interval on the inner peripheral side of the core 806a. Composed of and. Also rotor 807
Is composed of a rotor 807a in which an armature winding is fitted in a rotor core formed by laminating silicon steel plates, and a rotary shaft 807b. One end of the rotating shaft 807b is pivotally supported by a first bearing 808 fitted and fixed to the upper opening of the inner cylindrical body 804, and the other end of the rotating shaft 807b is fixed to the lower opening of the inner cylindrical body 804. It is axially supported by the second bearing 809.

One end of a pump case 901 of the submerged pump body 9 is fixed to the lower end of the motor case 802. In this example, the pump case 901 is composed of an upper case 902 and a lower case 903 which are vertically divided into two parts. The upper case 902 is composed of an outer cylindrical body 904 and an inner cylindrical body 905 like the motor case 802. Thus, the lower part of the lower case 903 opens toward the bottom wall of the container body 101 of the pump container 1. Outer cylinder 90
4 and the inner cylindrical body 905, the flow path 303 is
It communicates with the flow path 302 provided in the motor case 801. The upper end of the rotary shaft 906 of the pump body is directly connected to the rotary shaft of the motor 8 via the coupler 10.
An impeller 907 that constitutes a multi-stage axial flow pump is fixed to.

A suction pipe 111 forming a suction port 11 is provided on the side wall of the container body 101 of the pump container 1. The suction port 11 is provided on the outer cylindrical body 803 of the motor case 802.
Is open toward the outer peripheral surface. Also, the container body 101
A drain pipe 1 for pulling out the drain pipe 12 to the outside of the side wall of the
3 is provided. The drain pipe 12 is provided to draw out the residual liquid remaining in the pump container 1, and the open end of the drain pipe 12 is arranged close to the bottom wall of the pump container 1. The drain pipe 12 does not have to be pulled out to the outside through the inside of the pump container, and may be pulled out to the outside directly from the bottom wall portion of the pump container 1. In the above example, the pump drive motor 8 is arranged on the upper portion of the submerged pump body 9 to form a pump structure.

The LNG liquid has a very low temperature of -162 ° C. When starting the gas supply equipment etc. for the first time or restarting it after periodic inspection, when the low temperature liquid is injected into the submerged pump for low temperature liquid in normal temperature in a short time, each component that makes up the pump There is a problem that each part is deformed due to thermal strain due to the difference in thermal expansion coefficient. If the pump is started before the temperature of the entire pump is lowered by the low temperature liquid, the thermal strain generated in each part of the component is increased and the balance of each part is lost. In particular, if the rotor 807 of the motor 8 is greatly out of balance, it will be a source of large vibrations, which will greatly affect the life of the pump. Therefore, conventionally, when injecting the low temperature liquid into the submerged pump for low temperature liquid, the low temperature liquid is gradually injected, and when starting the pump, it takes a considerably long time until the entire pump is completely cooled. After I drop it, I try to start it. Such a treatment is called cool down of the cryogenic liquid pump. Currently, pump manufacturers generally recommend cooling rates of 50 ° C / hr or less.

When disassembling the low temperature liquid pump for inspection and repair, the low temperature liquid is discharged from the inside of the pump container 1 through the drain pipe 12, and pressurized nitrogen gas or the like is introduced into the pump container 1 through the vent 4. The temperature rising gas is filled at a low flow rate and the entire pump is heated to room temperature over a long time (tens of hours). This is because when the flow rate of the temperature rising gas is increased, the flow of the gas causes the impeller 9 of the submerged pump body 9 to move.
This is because 07 rotates and the rotation shaft 807a of the motor 8 also rotates. When the rotating shaft 807 rotates during the temperature rise, a large thermal strain is generated in the laminated steel plates, the bearings 808 and 809, etc. that compose the rotor 807a, and these members are deformed, causing the balance of the rotor 807 to be lost. Conventionally, the temperature rising gas is filled with a small flow rate.

[0007]

Conventionally, regarding a pump for low temperature liquid such as a submerged pump for low temperature liquid, there has been no method for accurately knowing the situation of the pump driving motor during cool down and hot up. For example, in order to know the situation of the pump driving motor at the time of cool down, a temperature sensor is attached to the outside of the side wall of the container body 101 of the pump container 1 or the outside of the motor case 802 to detect the temperature drop state during the cool down work and Attempts have been made to detect the completion of cooldown. However, the temperature sensor actually only measures the temperature of the portion to which the temperature sensor is attached, and it was not possible to know the temperature change inside the motor. Also, the motor 8 during hot-up
The rotation of the rotor 807 has been considered to be detected using a vibrometer or the like, but it is possible to simply and surely detect only the presence or absence of rotation of the rotor 807 without considering the vibration generated from surrounding devices. I couldn't. In general, it is rare to carry out cool-down and hot-up operations while measuring the flow rate, so in practice, within the range guaranteed by the manufacturer of the pump, we resorted to intuition to prevent the above problems from occurring. The reality is that by adjusting the valve opening, the cool-down work and the hot-up work are performed with not so high accuracy and taking a long time.

An object of the present invention is to provide a cool-down and hot-up method for a cryogenic liquid pump which can accurately detect the condition of a pump driving motor and can carry out cool-down and hot-up with higher accuracy than the conventional method. To do.

Another object of the present invention is to provide a cool-down method for a cryogenic liquid pump, which can accurately detect the condition of a pump driving motor and can perform cool-down with higher accuracy and faster than before. .

Another object of the present invention is to provide a cool-down method for a cryogenic liquid pump capable of accurately detecting the condition of a pump driving motor and detecting completion of cool-down faster than conventional methods. To do.

Still another object of the present invention is to hot-up a low temperature liquid pump capable of accurately detecting the condition of a pump driving motor and completing hot-up with higher accuracy and speed than in the conventional method. To provide a method.

[0012]

In any of the first to sixth aspects of the invention, the situation of the pump driving motor during the cool-down work or the hot-up work is measured, and the change in the resistance value of the winding of the motor is measured. The basic idea is to detect this or to measure this change in resistance value in advance, and to perform cool down or cool up using the measurement result.

The invention of claim 1 applies the above-mentioned basic idea to a cool-down method for a low-temperature liquid pump provided with a pump driving motor that is cooled by the injected low-temperature liquid. That is, the change in the resistance value of the winding of the pump driving motor is measured during the cool-down work, and the injection flow rate of the cool-down low-temperature liquid is adjusted so that the change rate of the resistance value is equal to or less than the limit change rate. On the other hand, in the invention of claim 2,
Measure the change in the resistance value of the winding of the pump drive motor during the cool-down work in advance, and determine the injection flow rate control pattern of the cool-down low-temperature liquid in which the rate of change of the resistance value is less than or equal to the limit change rate. Then, cool down is performed according to this control pattern.

According to a third aspect of the present invention, in a cool down method for a low temperature liquid pump having a pump driving motor that is cooled by a low temperature liquid to be injected, the completion of the cool down is detected by using the above basic idea. . That is, the resistance value of the winding of the pump driving motor is measured, and it is detected whether or not the cooldown is completed depending on whether or not the resistance value is equal to or less than the reference value.

According to a fourth aspect of the present invention, there is provided a low temperature liquid pump comprising a pump driving motor cooled by the injected low temperature liquid, and a rotary shaft of the pump driving motor is directly connected to a rotary shaft of a pump body. The above basic idea is applied to a hot-up method of a low-temperature liquid pump that fills a temperature-raising gas and raises the temperature. That is, while measuring the resistance value of the winding of the pump driving motor during hot-up work, the flow rate of the temperature rising gas is increased to detect the flow rate at which the resistance value of the winding increases or decreases as the limit flow rate. The temperature rising gas is supplied at a lower flow rate. On the other hand, according to the invention of claim 5, while measuring the resistance value of the winding of the pump driving motor in advance during the hot-up operation, the flow rate of the temperature rising gas is increased and the resistance value of the winding is changed. The flow rate is detected as a limit flow rate, and the flow rate of the temperature rising gas is adjusted within a range smaller than this limit flow rate.

The invention of claim 6 applies the above basic idea to both cool down and hot up. That is, the resistance value of the winding of the pump driving motor is measured during the cool-down and hot-up work, and the cool-down and hot-up work conditions are determined from the measurement results to control the cool-down and hot-up work.

[0017]

According to the first aspect of the invention, in order to know the cooling situation of the pump driving motor during the cool down, the change in the resistance value of the winding of the pump driving motor is measured during the cool down work. When the temperature inside the motor (stator core, winding) decreases, the resistance value of the winding also decreases accordingly. By utilizing this phenomenon, the cooling situation of the pump drive motor can be known from the rate of change of the resistance value of the winding. Further, the pump manufacturer presents a limit temperature decrease rate (° C./hr) with respect to the time during cooldown, and the limit change rate of the resistance value corresponding to this can be known. Therefore, by comparing the measured rate of change of the resistance value of the winding with the previously known limit rate of change, the cooling flow rate of the cool-down low temperature liquid is increased so that the rate of change of the resistance value is below the limit rate of change. It can be adjusted with precision. Further, the cooling rate can be increased by adjusting the liquid injection flow rate of the cool-down low-temperature liquid so that the rate of change of the resistance value approaches the limit rate of change as close as possible. Even when the rate of change of the resistance value is converted to the rate of change of the temperature and the rate of change of the temperature is compared with the limit rate of temperature change, the rate of change of the resistance value is indirectly compared. include.

According to the first aspect of the invention, it is necessary to measure the resistance value of the winding of the motor every time during the crew down work. However, if it is the same model, measure the resistance value of the winding at the test stage or at the time of the first cooldown work,
From the result, it is possible to determine the injection flow rate control pattern of the cool-down low-temperature liquid in which the rate of change of the resistance value is equal to or less than the limit rate of change. Therefore, in the second aspect of the present invention, the cooldown is performed according to the control pattern determined in advance. Therefore, according to the present invention, there is an advantage that it is not necessary to measure the resistance value every time when performing the cool down work.

According to the invention of claim 3 as well as the inventions of claims 1 and 2, in order to know the cooling situation of the pump driving motor at the time of cool down, the resistance of the winding of the pump driving motor during the cool down work is known. Measure the change in value. In the present invention,
The completion of cool down is detected by measuring the resistance value of the winding. When the temperature of the core and winding of the motor stator approaches the temperature of the low temperature liquid, the rate of change of the resistance value of the winding becomes small, and the resistance value tends to become a constant value. Therefore, it is possible to detect the completion of the cooldown with high accuracy and in the shortest time by determining the reference value in advance with reference to the constant value and detecting whether the measured value is less than or equal to the reference value. Become.

According to the fourth aspect of the present invention, in order to know the situation of the pump driving motor during hot-up, the change in the resistance value of the winding of the pump driving motor is measured during the hot-up work. As described above, the resistance value of the winding changes according to the temperature change of the motor stator. When the flow rate of the temperature rising gas filled during hot-up increases and the rotor of the motor rotates due to the flow of that gas, the residual magnetism remaining in the rotor moves, causing the resistance value of the winding to vibrate or Increase or decrease. In the present invention, by utilizing this phenomenon, the limit flow rate of the temperature rising gas for rotating the rotor of the motor is determined,
The flow rate of the temperature rising gas is adjusted within a range smaller than this limit flow rate. Since the change in the resistance value of the winding increases or decreases based on only the rotation of the rotor without being affected by the vibration generated from the surrounding equipment, the rotation of the rotor can be detected with high accuracy. As a result, according to the present invention, the limit flow rate can be determined with high accuracy, and hot-up can be performed with high accuracy and faster than before.

According to the invention of claim 4, it is necessary to measure the resistance value of the winding wire during the hot-up work. However, if the same model is used, the winding wire resistance can be measured at the test stage or when the first hot-up work is performed. By measuring the resistance value, the limit flow rate of the temperature rising gas can be known in advance from the result. Therefore, in the invention of claim 5, since the flow rate of the temperature-rising gas is adjusted within the range of the predetermined limit flow rate, the limit flow rate is not actually measured during the hot-up work, which is highly accurate and faster than the conventional method. Hot-up can be done.

According to the sixth aspect of the present invention, in order to know the situation of the pump driving motor in both the cool down and the hot up, the change in the resistance value of the winding of the pump driving motor is measured, and the cooling result is measured. Down and hot-up The cool-down and hot-up operations of the cryogenic pump can be controlled with extremely high accuracy because the cool-down and hot-up operations are controlled by determining the work situation.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 (A) to 1 (D) are schematic diagrams for explaining a cool-down process of a low temperature liquid when the embodiment of the method of the present invention is applied to the known submerged pump for low temperature liquid shown in FIG. Is. FIG. 1A shows a state at the time of cool down. In the present invention, the low temperature liquid is supplied to the pump container 1 from the tank or the pipe T filled with the low temperature liquid through the drain pipe 12. Initially control valves V1, V2
, V5 and V6 and the bypass valve Vp are closed,
The control valves V3, V4 and V7 are left open. Drain pipe 12
The injection flow rate or injection flow rate of the low temperature liquid supplied through
Set it so that it is below the limit cooling rate or limit temperature reduction rate guaranteed by the pump manufacturer. The method for determining the liquid injection flow rate will be described later. In this state, since the control valve V3 is opened, the internal gas is released to the outside through the vent 4 when the low temperature liquid is injected. Even if the injection of the low-temperature liquid is started through the drain pipe 12, the low-temperature liquid does not accumulate in the pump container 1 immediately after the injection because the low-temperature liquid is immediately vaporized while the temperature of the passage is high. .
The low temperature liquid starts to accumulate in the pump container 1 in about 1 to 2 hours after starting the injection. After the low temperature liquid has accumulated in the pump container 1 to some extent, liquid is injected from the drain pipe 12 so as to keep the liquid surface level constant. After a lapse of a predetermined time, as shown in FIG. 1 (B), the control valve V7 is closed to stop the liquid injection from the drain pipe 12. After that, the completion of cool down is detected. The method of detecting the completion of cool down will be described later. After the cool down is completed, the control valves V1 and V2 are opened to introduce the low temperature liquid into the pump container 1 through the suction port 11 and the control valve V3 is closed when the gas inside the pump container 1 is exhausted. When starting the operation of the pump, the control valves V4 and V5 are opened as shown in FIG. 1 (B) and then the motor 8 is started, and then the control valve V6 is opened as shown in FIG. 1 (C). And

A method for determining the liquid injection flow rate when performing the cool down and a method for detecting the completion of the cool down will be described. In the embodiment, the resistance value of the winding wire 806b wound around the stator 806a of the motor 8 is measured, and the measured resistance value is used to detect the cooling rate or the cooling state and the completion of the cool down. As described above, if the motor 8 is a three-phase induction motor and the winding 806b is star-connected as shown in FIG. 2, the winding resistance for two phases is measured as the resistance value of the winding. The terminal TM shown in FIG. 2 is arranged in a terminal box (not shown) connected to the connecting pipe 7 of FIG. Further, the configuration of the resistance measuring device RD shown in FIG. 2 is a schematic configuration, and it shows a measured value v of the voltmeter V and a measured value i of the ammeter I when a DC voltage is applied from the DC power supply DC. From the resistance value r of the fixed resistor R, the winding resistance ro between the two phases is obtained from the equation ro = kr / (r-k). In this equation, k = v / i. In order to improve the measurement accuracy, a bridge circuit may be used for the measurement.

In the temperature range from room temperature to about -160 ° C,
There is a linear proportional relationship between the resistance of the winding and the temperature,
If the resistance value is known, it is possible to estimate the average temperature inside the motor (the stator core and the winding). Specifically, the temperature can be estimated from the measured resistance value by using the relational expression of the expression (2) derived from the following expression (1).

Rt = Rt1 [1 + α _ti (t−ti)] (1) t = [(Rt −Rti) / α _ti · Rti] + ti (2) In the above equations, t is an arbitrary temperature (° C.). ), Ti is a known temperature (° C.) during resistance measurement, Rt is a resistance value (Ω) at an arbitrary temperature t, Rti is a known resistance value (Ω), and α
_ti is the constant mass temperature coefficient at temperature ti.

The rate of temperature decrease inside the motor during the cool-down work can be known from the rate of change of the resistance value. Further, the critical temperature decrease rate can also be expressed as a rate of change in resistance value. Therefore, if the resistance value of the winding is measured during the cool-down work and the liquid injection flow rate is adjusted while observing the measurement result, the cool-down can be performed faster than before with a decrease rate closer to the critical temperature decrease rate. Also, if you look at the measurement results, there is no risk of cooling down at a temperature decrease rate that exceeds the limit temperature decrease rate,
The control accuracy can be improved. Although it is troublesome,
Of course, the measured resistance value may be converted into temperature and the rate of temperature decrease may be used to adjust the liquid injection flow rate. With the same model, it is possible to determine a preferable liquid injection flow rate control pattern from past measurement results without measuring the resistance value each time the cooldown work is performed. The injection flow rate of the low temperature liquid for down may be adjusted.

When cooling is performed by the cool-down work, the temperature of the core and the winding approaches the temperature of the low temperature liquid, the rate of change of the resistance of the winding decreases, and the resistance approaches a constant value. Therefore, it is possible to detect the completion of the cool-down by measuring the resistance value of the winding and determining whether or not the resistance value becomes smaller than the reference value. This reference value should be within the range of the temperature difference that does not hinder the operation of the motor, and the resistance value is 5 to 10% larger than the resistance value when the motor matches the temperature of the low temperature liquid. You can do this.

A test for confirming the effect of the present invention at the time of cool down was conducted by using JC Carter Co., Ltd. (JC Carter CO., Ltd.).
d. ) Manufactured submerged pump (Discharge rate: 85 T
/ Hr, head; 530 mLNG). In addition to measuring the resistance value of the winding, the temperature of the side wall of the container body of the pump container and the temperature inside the container body were measured using a temperature sensor for reference. FIG. 3 shows the measurement results, in which the horizontal axis represents time, the left vertical axis represents the resistance value, and the right vertical axis represents the temperature. In FIG. 3, a curve A shows the measured value of the resistance value of the winding, a curve B shows the measured value of the temperature of the side wall of the pump container, and a curve C shows the measured value of the temperature inside the pump container. Shows. Further, in FIG. 3, the straight line D corresponds to the limit temperature change rate (50 ° C./hr) or the resistance limit change rate. The resistance value and the temperature of the side wall of the pump container were measured 55 minutes before the start of the cool-down work. The temperature of the side wall of the pump container immediately after the start of measurement was 4.4 ° C. When 55 minutes had elapsed from the start of the measurement, the LNG liquid was injected from the drain pipe as a low temperature liquid for cooling down at a flow rate of about 0.5 m ³ / hr. As can be seen from the curve C in FIG. 3, if the time at which the injection is started is 0:00, the temperature in the pump container drops to the limit value within 1 hour after the injection is started. The temperature decrease on the side wall of the motor (curve B) is slow, and the temperature decrease inside the motor (curve A) is slower.
About 2 hours after starting the injection of the low temperature liquid,
There is a fairly large temperature difference between the temperature of the side wall of the pump container and the temperature inside the motor. This means that it is not easy to cool down the inside of the motor. About two hours after the start of the liquid injection, it was detected by the liquid level meter arranged in the pump container that the low temperature liquid started to be accumulated in the pump container. From 3 hours and 10 minutes after starting the injection, use the level control system so that the amount of the low temperature liquid injected from the drain pipe will be a constant level (about 400 mm) in the pump container. It was After that, the injection of the low temperature liquid from the drain pipe was stopped, and the injection liquid was switched to the injection pipe. When 4 hours and 25 minutes have passed since the start of the liquid injection, it was detected that the measured resistance value was 1.32Ω (reference value RL) [corresponding to -149 ° C], and the cool down was completed. Was detected. In this test, when 5 hours and 30 minutes had passed since the injection was started, it was detected that the resistance value was 1.18Ω (corresponding to −158 ° C.), and the measurement was terminated. The resistance value is 1.1
If it becomes 6Ω, it can be said that the internal temperature of the motor has dropped to the temperature of the LNG liquid of −160 ° C. In order to cool down the fastest, the rate of change of the resistance value curve A (the rate of change of the resistance value) should be brought close to the limit rate of change of the straight line D.
The injection flow rate of the low temperature liquid may be adjusted.

Next, an example of performing the hot-up work will be described. When performing hot-up work,
As shown in FIG. 1D, the control valves V1, V2, V5 and V6 are closed and the control valves V4 and V7 are opened. Drain pipe 1 is used to return the entire pump to room temperature (hot-up work).
The low temperature liquid remaining in the pump container is discharged to the outside through 2 and then pressurized nitrogen gas is supplied from the vent 4. In order to reduce the occurrence of thermal strain during hot-up as much as possible, the hot-up work is performed by keeping the rotor of the motor from rotating as much as possible by the heated gas and taking a long time until the temperature of the entire pump reaches room temperature. . In this embodiment,
In order to make the hot-up work as fast as possible, the maximum allowable flow rate or the limit flow rate of the temperature rising gas is detected, and the hot-up work is performed within the range of this limit flow rate.
First, in order to know the situation of the pump drive motor during hot-up, the change in the resistance value of the winding of the pump drive motor is measured during the hot-up work. To measure this resistance,
It is possible to directly use the measuring device for measuring the resistance value during the above-mentioned cool down work. During the hot-up work, if the temperature inside the motor rises, the resistance value of the winding rises accordingly. Then, as the flow rate of the temperature rising gas increases, the rate of increase in resistance increases. The inventor has found that when the flow rate of the temperature rising gas charged during hot-up becomes too large, the rotor of the motor rotates due to the flow of the gas, and the residual magnetism remaining in the rotor moves as the rotor rotates. Therefore, it was found that the resistance value of the winding vibrates or increases or decreases. FIG. 4 shows this phenomenon in a simplified manner. In the present invention, by utilizing this phenomenon, the limit flow rate of the temperature rising gas for rotating the rotor of the motor is determined, and the flow rate of the temperature rising gas is adjusted within a range smaller than this limit flow rate. When a test was performed using the submerged pump for low temperature liquid used in the above cool-down test, when the flow rate of the temperature rising gas was set to about 2 m ³ / hr or more, the resistance value increased or decreased. Therefore, the temperature rising gas was supplied at a flow rate smaller than this value, 1.8 m ³ / hr. Similar to the detection of the completion of the cool down, the reference value (specifically, 3.6
Ω) is set and the completion of the hot-up work is detected by whether or not the resistance value of the winding is equal to or higher than the reference value. As a result, it could be detected that the hot-up work was completed in about 31.5 hours.

For the same model, the resistance value of the winding can be measured at the test stage or at the time of the first hot down work, and the limit flow rate of the temperature rising gas can be known in advance from the result, so it is determined in advance. It goes without saying that the flow rate of the temperature rising gas may be adjusted within the range of the limit flow rate.

In the above embodiment, the cool-down low-temperature liquid is injected from the drain pipe using the novel cool-down method, but as is well known, the cool-down low-temperature liquid is injected from the suction port. Of course, the present invention can be applied to such cases.

In both the cool down and the hot up, the best control result can be obtained by using the measurement result of the resistance value of the winding. However, the resistance value of the winding can be obtained only by one of the cool down and the hot up. It goes without saying that the measurement result of 1 may be used.

In the above embodiment, the present invention is applied to the so-called pot type low temperature liquid pump shown in FIG. 5, but the present invention can also be applied to the so-called in-tank type low temperature liquid pump. What is the in-tank type low temperature liquid pump?
Unlike the pump of FIG. 5, it does not have a pump container, and is arranged in a storage tank for storing a low temperature liquid and directly discharges the low temperature liquid in the tank.

[0035]

According to the first aspect of the present invention, the cooling flow rate of the cool-down low-temperature liquid can be adjusted with high accuracy so that the rate of change of the resistance value of the motor winding is less than or equal to the limit rate of change.
There is an advantage that the cool-down speed can be increased by adjusting the liquid injection flow rate of the cool-down low-temperature liquid so that the change rate of the resistance value approaches the limit change rate as close as possible.

According to the second aspect of the invention, since the cooldown is performed according to the control pattern determined in advance, there is an advantage that it is not necessary to measure the resistance value every time the cooldown work is performed.

According to the invention of claim 3, it is possible to detect the completion of the cool down with high accuracy and in the shortest time by detecting whether or not the resistance value of the winding is equal to or less than the reference value. .

According to the fourth aspect of the invention, the limit flow rate of the temperature rising gas can be determined with high accuracy, and there is an advantage that hot-up can be performed with high accuracy and faster than before.

According to the fifth aspect of the present invention, since the flow rate of the temperature rising gas is adjusted within the predetermined limit flow rate range, the limit flow rate is not actually measured during the hot-up operation,
There is an advantage that hot-up can be performed with high accuracy and faster than in the past.

According to the invention of claim 6, the change of the resistance value of the winding of the pump driving motor is measured, and the cool down and hot up work conditions are judged from the measurement result to control the cool down and hot up work. Therefore, there is an advantage that the cool-down and hot-up of the low temperature liquid pump can be controlled with extremely high accuracy.

[Brief description of drawings]

1A to 1D are views for explaining an embodiment of a method of the present invention.

FIG. 2 is a circuit diagram for explaining a method of measuring a resistance value of a winding of a motor.

FIG. 3 is a graph showing test results when cooldown was performed according to an example of the method of the present invention.

FIG. 4 is a diagram showing a relationship between a flow rate of a temperature rising gas and a change in resistance value of a winding when hot-up is performed.

FIG. 5 is a cross-sectional view showing an example of the structure of a known low temperature submerged pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump container 101 Container body 102 Lid body 2 Discharge port 301-303 Flow path 4 Vent 5 Conduit tube 6 Electric wire 8 Pump drive motor 801 Motor main body 802 Motor case 806 Stator 806a Core 806b Winding 807 Rotor 809,809 Bearing 9 Submerged Pump body 901 Pump case 11 Suction port 12 Drain pipe V1 to V7 Control valve Vp Bypass valve TM Terminal RD Resistance measuring device DC DC power supply R Resistance I Ammeter V Voltmeter T Low temperature liquid tank or piping

Front page continued (72) Minor Yoshida Minoru Yoshida 25 Shintomi, Futtsu City, Chiba Prefecture Tokyo Electric Power Company Futtsu Thermal Power Plant (72) Inventor Yukio Aoki 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama, Kanagawa Chiyoda In Construction Co., Ltd. (72) Inventor Shinsuke Michi 12-12 Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kako Construction Co., Ltd. (72) Inventor Katsuhiko Yui 12-12, Tsurumi-chuo, Tsurumi-ku, Yokohama-shi, Kanagawa No. 1 in Chiyoda Kakoh Construction Co., Ltd. (72) Inventor Ichino Ninomiya 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kakoh Construction Co., Ltd.

Claims (6)

[Claims] 1. A cool-down method for a low-temperature liquid pump including a pump-driving motor that is cooled by a low-temperature liquid to be injected, the resistance value of a winding wire of the pump-driving motor during a cool-down operation. The method for cooling down a low-temperature liquid pump is characterized in that the flow rate of the low-temperature liquid for cooling down is adjusted so that the rate of change of the resistance value becomes equal to or lower than the limit rate of change. 2. A cool-down method for a low-temperature liquid pump provided with a pump-driving motor that is cooled by a low-temperature liquid to be poured, wherein the resistance of windings of the pump-driving motor during a cool-down operation in advance. It is characterized in that the change rate of the resistance value is measured, a liquid injection flow rate control pattern of the low-temperature liquid for cooldown in which the rate of change of the resistance value is equal to or lower than the limit rate of change is determined, and the cooldown is performed according to the control pattern. Cooling down method for low temperature liquid pump. 3. A cool-down method for a low-temperature liquid pump equipped with a pump-driving motor cooled by a low-temperature liquid to be poured, wherein a resistance value of a winding of the pump-driving motor is measured, A cool down method for a low temperature liquid pump, comprising detecting whether or not the cool down is completed depending on whether or not the resistance value is equal to or lower than a reference value. 4. A low temperature liquid pump comprising a pump driving motor that is cooled by a low temperature liquid to be poured, and a rotary shaft of a pump body is directly connected to a rotary shaft of the pump driving motor, A method for hot-uping a low-temperature liquid pump for filling and heating the temperature of the pumping motor by increasing the flow rate of the temperature-rising gas while measuring the resistance value of the winding of the pump driving motor during hot-up operation. A method for hot-up of a pump for low temperature liquid, characterized in that a flow rate at which a resistance value of a winding changes to increase or decrease is detected as a limit flow rate, and the temperature rising gas is supplied at a flow rate lower than the limit flow rate. 5. A pump for a low temperature liquid in which a pump driving motor is cooled by a low temperature liquid and a rotary shaft of a pump body is directly connected to an output shaft of the pump driving motor is filled with a heating gas to raise the temperature. A method for hot-uping a pump for low-temperature liquid, comprising: measuring a resistance value of a winding wire of the pump driving motor during hot-up work in advance, increasing a flow rate of the temperature rising gas, and then increasing a resistance value of the winding wire. Is detected as a limit flow rate, and the flow rate of the temperature rising gas is adjusted within a range smaller than the limit flow rate. 6. A cool-down and hot-up method for a low-temperature liquid pump, wherein a pump-driving motor is cooled by a low-temperature liquid, and a rotary shaft of a pump body is directly connected to an output shaft of the pump-driving motor, Characterizing that the resistance value of the winding of the pump driving motor is measured during the cool-down and hot-up work, and the cool-down and hot-up work conditions are determined from the measurement results to control the cool-down and hot-up work. Cool-down and hot-up method for low temperature liquid pump.