JP2000003811A - Helium recovering equipment for superconducting coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide helium recovering equipment for a superconducting coil, which leads low temperature helium gas generated from the superconducting coil to a recovery tank, while controlling the temperature of the helium gas. SOLUTION: This helium recovering equipment is provided with a evacuated thermally insulating pipe 2 which is connected with a superconducting apparatus 1 and conducts helium, and a recovery tank 3 which is connected with the evacuated thermally insulating pipe 2 and accommodates helium. In the evacuated thermally insulating pipe 2, heaters H1-H4 and thermometers T1-T5 are installed, and according to the measured values of the thermometers, outputs of the heaters H1-H4 are controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helium recovery device for a superconducting coil for recovering helium therein when a quench phenomenon occurs in the superconducting coil.

[0002]

2. Description of the Related Art When a quench phenomenon occurs in a superconducting coil, the internal temperature rises and the pressure of helium gas rises.
The internal gas must be released to the outside. Here, the quench phenomenon means that a part of the superconducting wire forming the superconducting coil exceeds the frictional heat, the critical state of the superconducting wire (magnetic flux density, strain rate, temperature), or the current transition phenomenon,
The transition from the superconducting state to the normal conduction state. When the transition to the normal conduction occurs, Joule heat is generated at the transferred part, and the normal conduction part propagates in a chain. The helium gas cooling the superconducting coil is heated by this heat generation, and the pressure of the helium gas increases.

[0003] When the quench phenomenon occurs, the pressure of the helium gas increases, so that in order to prevent damage to the superconducting coil, it was directly released to the atmosphere on a laboratory scale.
In a practical-scale plant, it is collected in a tank. In this case, the temperature of helium near the superconducting coil is as low as about 4.5K, and a helium gas is collected at a low temperature tank (usually cooled to about 80K with liquid nitrogen,
It is called 80K medium pressure recovery tank. If the helium gas generated in (1) is directly introduced, the tank is damaged by thermal shock.
For this reason, a heater is provided, which is heated by the atmosphere to about 80K before being collected in the tank.

[0004]

However, superconducting coils for fusion reactors and electric power storage have a huge amount of helium gas storage and a huge amount of stored energy. , Using large-diameter piping,
It is necessary to install many heaters. Also, in a quench gas line using vacuum insulation pipes, low-temperature gas flows directly into the recovery tank, and there is a risk of thermal stress cracking of the tank.

The present invention has been made in view of the above-mentioned problems, and provides a helium recovery device for a superconducting coil in which the temperature of a low-temperature helium gas generated from a superconducting coil is controlled and guided to a recovery tank. Aim to be.

[0006]

According to the first aspect of the present invention, there is provided a vacuum insulating pipe connected to a superconducting coil device for guiding helium, a recovery tank connected to the vacuum insulating pipe and containing helium. , And a heater and a thermometer are provided in the vacuum insulation pipe, and the output of the heater is controlled according to the measurement value of the thermometer.

[0007] A quench phenomenon occurs, and the generated helium gas is led to a vacuum heat-insulating pipe. The temperature of the helium gas is measured by a thermometer in the vacuum insulated pipe, heated by a heater until the temperature does not give a thermal shock to the recovery tank, and sent to the recovery tank. This allows the recovery tank to be free from thermal shock.

According to the second aspect of the present invention, a pressure gauge is provided near the entrance and the exit in the vacuum insulation pipe, and the output of the heater is controlled according to the pressure difference between the two pressure gauges.

If the output of the heater is too large, heat friction loss occurs, making it difficult for helium gas to flow, and reducing the pressure difference of the pressure gauge. In this case, heating is suppressed by reducing the output of the heater. If the pressure difference is large and the temperature of the helium gas is low, the heating is increased.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a helium recovery device for a superconducting coil according to an embodiment. Superconducting coil 1
Is cooled by helium and has a temperature of about 4.5K. The vacuum insulation pipe 2 is composed of a double pipe, and the inner pipe 5
And the outer tube 6, the space between the inner tube 5 and the outer tube 6 constitutes a heat insulating layer as a vacuum, and helium gas flows in the inner tube 5. One end of the inner pipe 5 is connected to the superconducting coil 1 via the valve 4, and the other end is connected to the 80K medium pressure recovery tank 3. 80K medium pressure recovery tank 3 is liquid nitrogen (temperature 78k)
Is a tank that is maintained at a temperature of approximately 80 k.

[0011] Four electric heaters H1, H2, H3, and H4 are provided along the axis on the outer periphery of the inner pipe 5 of the vacuum heat insulating pipe 2. Thermometers T1, T2, T3 each having a measuring section inside the inner tube 5 on the upstream side in the helium gas flow direction of each heater.
T4 and a thermometer T5 having a measuring section at the outlet of the inner tube 5 are provided. Further, pressure gauges P1 and P2 each having a measurement section at the entrance and the exit inside the inner pipe 5 are provided. Each of the heaters H1 to H4 is controlled by a heater control device. The measurement data of each of the thermometers T1 to T5 is sent to a personal computer 9 via a temperature transmitter 8, and the personal computer 9 outputs the data of each of the heaters H1 to H4 based on the data of each of the thermometers T1 to T5 and the pressure gauges P1 and P2. The control data is instructed to the heater control device 7.

Next, the operation when the quench phenomenon occurs will be described. In order to release the pressure of the helium gas generated in the superconducting coil 1 due to the quench phenomenon, the valve 4 between the superconducting coil 1 and the vacuum insulation pipe 2 is opened. In the superconducting coil 1, the pressure of helium rises, but the temperature of the pressure relief port is around 4.5K, so the temperature of helium itself drops due to adiabatic expansion.
On the other hand, since the temperature of the inner tube 5 of the vacuum heat insulating pipe 2 is between 80K and 300K (normal temperature), the released helium is warmed. At the initial stage of releasing helium, vacuum insulation pipe 2
Helium gas having a temperature approximately equal to the temperature of the vacuum heat insulating pipe 2 before the release of helium flows into the 80K medium pressure recovery tank 3. Although depending on the shape of the vacuum heat insulating pipe 2, the vacuum heat insulating pipe 2 is also cooled over time, and the helium gas having a low temperature flows into the 80K medium pressure recovery tank 3. Here, since the heat capacity of the 80K medium pressure recovery tank 3 is larger than the heat capacity of the vacuum adiabatic pipe 2, a temperature difference occurs between the flowing helium gas temperature and the temperature of the 80K medium pressure recovery tank 3. If left as it is, a large temperature difference will occur and 80K due to thermal shock
The medium pressure recovery tank 3 has a risk of being broken. Therefore, while monitoring the temperature of the inner pipe 5 of the vacuum insulation pipe 2, the helium released by the heaters H1 to H4 provided in the vacuum insulation pipe is heated.

The output of the heaters H1 to H4 is controlled by a thermometer T.
The measurement is performed based on the measured values of 1 to T5 and the pressure difference between the pressure gauges P1 and P2. The output control by the thermometers T1 to T5 adjusts the outputs of the heaters H1 to H4 so that the temperature of the flowing helium becomes a predetermined temperature according to the positions of the thermometers T1 to T5. Performing temperature control in a small section
This is because the physical properties of helium change with temperature and pressure. In addition, the output control based on the differential pressure is based on the output of the heaters H1 to H4 (if the amount of heat passing per unit length of the vacuum heat insulating pipe 2 is too large, heating friction loss occurs and helium gas does not flow. The output is adjusted so that is equal to or more than a predetermined value.When the differential pressure at both ends of the vacuum heat insulating pipe 2 becomes equal to or less than a predetermined value, the outputs of the heaters H1 to H4 are reduced to make the differential pressure equal to or more than a predetermined value. The outputs of the heaters H1 to H4 are adjusted so that the values of the thermometers T1 to T5 become predetermined values.

FIG. 2 shows thermometers T1 to T5 and pressure gauges P1 and P1 based on heater output control performed by the occurrence of a quench phenomenon.
It is a figure which shows the measurement value of 2. Indicates the start of helium gas generation, indicates the start of control of the heater H1 by the thermometer T2, indicates the start of control of the heater H2 by the thermometer T3, and indicates the start of control of the heater H3 by the thermometer T4. In this case, since the temperature of the thermometer T5 has reached the predetermined temperature of 80K, the heater H4 is not heated. Further, the pressure difference between the pressure gauges P1 and P2 is equal to or higher than a predetermined value, indicating that the helium gas is flowing properly.

[0015]

As is apparent from the above description, the present invention provides a vacuum insulation pipe for guiding helium gas generated by a quench phenomenon from a superconducting coil to downstream equipment such as a recovery tank, and a heater provided inside the pipe. In addition, the outlet temperature is controlled to protect the equipment mounted downstream from thermal shock.
This makes it possible to reduce the size of the conventionally used heater even if it is unnecessary or provided. Further, by controlling the amount of heat input to the heater from the temperature and the pressure, it is possible to anticipate a heating friction loss and to effectively heat and recover the helium gas.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 shows data of a thermometer and a pressure gauge under heater control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Superconducting coil 2 Vacuum insulation pipe 3 80K medium pressure recovery tank 4 Valve 5 Inner pipe 6 Outer pipe 7 Heater control device 8 Temperature transmitter 9 Personal computer

Claims (2)

[Claims] 1. A vacuum insulation pipe connected to a superconducting coil device for guiding helium, and a recovery tank connected to the vacuum insulation pipe and containing helium, wherein a heater and a thermometer are provided in the vacuum insulation pipe. A helium recovery device for a superconducting coil, wherein an output of the heater is controlled in accordance with a value measured by the thermometer. 2. The helium of a superconducting coil according to claim 1, wherein a pressure gauge is provided near an inlet and an outlet in the vacuum insulation pipe, and an output of the heater is controlled in accordance with a pressure difference between the two pressure gauges. Collection device.