JP2001255033A - Method for operating helium cooling system and method for generating power using helium cooling system and power generating system comprising helium cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precool helium gas efficiently in a helium cooling system. SOLUTION: In the operating method for a helium cooling system 90 comprising a heat exchanger having a plurality of stages for exchanging heat between helium flowing through a high pressure line and helium flowing through a low pressure line, helium gas is preliminarily cooled in a high temperature side heat exchanger by exchanging heat with liquefied natural gas. A power generating system is constituted by providing a gas turbine generator 20 for combusting natural gas vaporized through heat exchange and converting it into electric energy. Furthermore, the helium cooling system 90 is connected with a superconducting energy storage unit 30 for storing liquid helium, and electric energy generated from the gas turbine generator 20 is stored in the superconducting energy storage unit 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helium cooling device for cooling helium, which is a cooling medium for superconducting magnets used in nuclear fusion, superconducting energy storage, accelerators, NMR, linear motor cars, and the like.

[0002]

2. Description of the Related Art A conventional helium cooling device described in, for example, Japanese Patent Publication No. 6-10564 is known. This device includes a low-pressure line for leading the evaporated helium gas in the cryostat to the outside, a compressor for compressing the led-out helium gas, and a high-pressure line for supplying the compressed helium gas to the cryostat side. Helium flowing through the high-pressure line is precooled by heat exchange with liquid nitrogen in a cold box containing a plurality of stages of heat exchangers, and is mixed with low-temperature helium gas flowing through the low-pressure line. It is also cooled by heat exchange, is further expanded by Joule-Thomson with an expansion valve, is liquefied, and is then reduced to the cryostat. In addition, a part of the helium gas flowing through the high pressure line is guided to the expansion turbine to perform work, thereby generating the cold required for cooling the helium.

[0003]

In the conventional method and apparatus described above, since the cooling heat of liquid nitrogen is used for pre-cooling the helium gas in the vicinity of room temperature, the refrigeration capacity required for the helium cooling device is large. However, in order to supply liquid nitrogen corresponding to this, a liquid nitrogen production facility must be additionally provided, and there is an inconvenience that the equipment failure increases and the installation space and capital investment increase accordingly. It is also conceivable to provide a turbine expander for generating cold at 80 K level in place of such liquid nitrogen production equipment, but as in the above case, the equipment space and equipment investment will still increase, and the saturation temperature will be stable. Temperature stability may be worse than when using liquid nitrogen.

[0004] Further, the nitrogen gas generated by the evaporation of liquid nitrogen during the precooling is currently discharged to the atmosphere as it is, and there is a problem that energy is wasted very much.

[0005]

The present inventors have focused on liquefied natural gas as a means for solving the above-mentioned problems. This liquefied natural gas is stored and transported in the liquid phase,
During use, it is subjected to forced evaporation by heat exchange with seawater, etc., and is provided as natural gas at room temperature,
At present, the cold generated during the evaporation is wastefully discarded together with the seawater.

The present invention has been made in view of such circumstances, and has a low-pressure line for leading helium gas in a cryogenic container to the outside of the container, and a compression for compressing the helium gas led through the low-pressure line. And a high-pressure line for introducing helium gas discharged from the compressor into the cryogenic vessel, and perform heat exchange between the helium gas flowing through the high-pressure line and the helium gas flowing through the low-pressure line. A helium cooling device for reducing the cooled helium into the cryogenic vessel, comprising a plurality of stages of heat exchangers to be cooled, and a cold generating means for generating cold for helium cooling. Helium gas in the high-pressure line is pre-cooled by exchanging heat with liquefied natural gas in the heat exchanger on the highest temperature side. It is intended to recover the natural gas vaporized me.

In this method, since pre-cooling is performed by heat exchange between liquefied natural gas and helium gas in the highest temperature heat exchanger, there is a demand for evaporating the liquefied natural gas to produce natural gas, and a need for compression. The demand for pre-cooling the helium gas by cooling the helium gas discharged from the machine can be simultaneously satisfied. Therefore, compared with the conventional method and apparatus for liquefying nitrogen only for the purpose of pre-cooling helium gas and discharging the nitrogen gas generated after pre-cooling as it is to the atmosphere, the amount of wastefully released energy is extremely reduced. In addition, the driving efficiency can be dramatically improved.

The natural gas generated by the pre-cooling of helium can be provided to each household or the like as, for example, city gas. However, the natural gas is burned and its energy is converted into mechanical energy by a gas turbine or the like. By converting to electric energy, a highly efficient power generation system can be constructed. The present invention is also such a power generation system and a power generation method. For example, by providing a gas turbine generator, helium gas in a high pressure line discharged from the compressor is heat-exchanged with liquefied natural gas by a heat exchanger on the highest temperature side. In this way, the pre-cooling is performed, and natural gas vaporized by the heat exchange is burned to convert the energy into electric energy.

The electric energy generated by this system can be used as a power source for helium cooling equipment and other equipment. In addition, a superconducting energy storage device that keeps a superconducting magnet cooled with liquid helium is connected to the helium cooling device as the cryogenic container, and the electric energy is stored in the superconducting energy storage device. An ideal energy system that can be efficiently absorbed inside can be realized.

[0010] Specifically, in the power generation system,
A superconducting energy storage device that is connected to the helium cooling device as the cryogenic container, cools a superconducting magnet with liquid helium, and stores electromagnetic energy with the superconducting magnet, and converts the electric energy generated by the gas turbine generator into the superconducting energy. An electric power supply line for supplying to the energy storage device may be provided, and the supplied electric energy may be stored in the superconducting energy storage device.

[0011]

Embodiments of the present invention will be described with reference to the drawings.

The helium cooling device shown in FIG.
P is connected to a cryostat (cryogenic vessel) 80 on the discharge side via a high-pressure line 91 and on the suction side via a low-pressure line 92. Both lines 9
Numerals 1 and 92 pass through the cool box 95.
Inside, a multi-stage heat exchanger 9 for exchanging heat between helium gas passing through the high pressure line and helium gas passing through the low pressure line.
4A, 94B, 94C, 94D, 94E and 94F are accommodated.

The cold generating means for helium cooling includes a high-pressure line 91 between the second-stage heat exchanger 94B and the third-stage heat exchanger 94C from the high-temperature side, and a second-stage heat exchanger from the low-temperature side. A cold generation passage 97 connecting the low-pressure line 92 between the heat exchanger 94E and the lowest-temperature-side heat exchanger 94F;
The cold generation passage 97 passes through the heat exchanger 94D, and has cold generation expanders (for example, expansion turbines) 98A and 98B on its upstream side and downstream side, respectively. Further, an expansion valve 96 for liquefying helium is provided in the high-pressure line 91 downstream of the lowest-temperature-side heat exchanger 94F.

In this apparatus, a cryostat 80 is used.
The helium gas evaporated inside is sucked into the compressor CP through the low-temperature line 92, compressed, and
Is discharged to the cryostat 80 side. The discharged high-pressure helium gas is supplied to the heat exchangers 94A to 94E.
Is cooled by exchanging heat with the helium gas on the low pressure line 92 side, further expanded by Joule-Thomson by the expansion valve 96, liquefied, and then reduced to the cryostat 80. A part of the helium gas flowing through the high-pressure line 91 is diverted to the cold generation passage 97 and works with the expanders 98A and 98B, and then returned to the low-pressure line 92, thereby being necessary for cooling the inside of the cryostat 80. Cold is generated.

Further, as a feature of this apparatus, the heat exchanger 94A on the highest temperature side is provided with a liquefied natural gas supply line 10 for passing liquefied natural gas as a helium gas pre-cooling cryogenic liquid, and has a pre-cooling heat exchange line. In the heat exchanger 94A, the helium gas is pre-cooled by exchanging heat between the high-pressure helium gas discharged from the compressor CP and the liquefied natural gas. The 94A specification is designed.

As described above, if liquefied natural gas is used as the pre-cooling low-temperature liquid that is heat-exchanged with room-temperature helium gas, pre-cooling of the helium gas and conventionally using the heat of seawater are performed. The operation of evaporating liquefied natural gas to natural gas can be achieved at the same time.

Then, by recovering the natural gas vaporized by the evaporation operation, the natural gas can be directly provided to each household or the like as city gas, and the energy possessed by the natural gas can be used as electric energy. By converting to, self-generation with high efficiency can be performed. FIG. 2 shows an example of the power generation system.

In the figure, natural gas (NG) evaporated in a heat exchanger 94 A of a helium cooling device 90 is sent to a compressor 14 through a gas supply line 12, and compressed by a gas turbine generator through a gas supply line 16. Machine 20
Supplied to

The gas turbine generator 20 includes an air compressor 21, a gas turbine 22, a generator 23, and a combustor 25. The air compressor 21 and the gas turbine 22 are connected via a rotating shaft so as to rotate synchronously with each other, and the rotational energy of the gas turbine 22 is converted into electric energy by the generator 23.

In this gas turbine generator 20, natural gas introduced into the combustor 25 from the compressor 14 via the gas supply line 16 is mixed with compressed air also introduced from the air compressor 21 into the combustor 25. And is burned in the combustor 25. The energy is converted into mechanical energy (turbine rotation energy) by the gas turbine 22 and further converted into electric energy by the generator 23 and output.

The generated electric energy can be effectively used for electric power in a power station or a city gas supply base, or can be organically coupled to the helium cooling device 90 to generate a self-power generation type power generation system. It is also possible to construct An example is shown in FIG.

In the figure, a helium cooling device 90 includes:
A superconducting energy storage device 30 is connected as the cryogenic container. This superconducting energy storage device 30
Is provided with a helium container for storing liquid helium generated by the helium cooling device 90, and a superconducting coil immersed in the liquid helium and kept cool, and stores electric energy by confining a permanent current in the superconducting coil. And the high-pressure line 9 of the helium cooling device 90
1 through the liquid helium supply pipe 32 to supply the liquid helium and the superconducting energy storage device 30
The helium gas inside the helium cooling device 90 is recovered through the gas recovery pipe 34 to the low pressure line 92.

Power lines 36 and 37 are connected to a superconducting coil in the superconducting energy storage device 30. The power line 36 reaches the power output section of the gas turbine generator 20, and an open / close switch S1 for appropriately shutting off the power line 36 is provided in the middle of the power line 36. A changeover switch S2 is connected to a power input portion of a power circuit 40 of the facility including the helium cooling device 90 through a power line 38. By the changeover operation of the changeover switch S2, the power line 38 The state connected to the line 37 and the power line 38
Is switched to a state of being connected to the power output unit of the gas turbine generator 20. The power supply line 36 is connected to a power output section of a power circuit 40 via a power line 39.
Is also provided with an open / close switch S3.

According to this system, the open / close switch S1
Is closed, and the electric energy generated by the gas turbine generator 20 is supplied to the superconducting energy storage device 30 through the power line 36, whereby the electric energy can be stored in the superconducting energy storage device 30. Further, even when surplus power is generated in the power circuit 40, the switch S3 is closed and the surplus power is transferred to the superconducting energy storage device 3 through power lines 39 and 36.
By supplying it to 0, it can be stored in the same device 30. Conversely, by appropriately operating the changeover switch S2 with the open / close switches S1 and S3 open, the output power of the gas turbine generator 20 and the output power of the superconducting energy storage device 30 are transmitted through the line 38 to the power circuit 40.
Can be powered.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the case of a conventional helium cooling device (a device using liquid nitrogen as a pre-cooling medium) having a cooling capacity of 100 kW at 4.5 K, a maximum of approximately 60,000 L / h (13.3 kg / s) of liquid nitrogen supply. The refrigeration capacity Q of such liquid nitrogen is
The enthalpy of the liquid nitrogen at 77K under atmospheric pressure
29.397kJ / kg, enthalpy at room temperature 300K 462.145kJ / k
Assuming g, Q = 13.3 * (462.145−29.397) = 5775.5kW.

On the other hand, in the present invention using liquefied natural gas, the required supply amount G of liquefied natural gas corresponding to the refrigerating capacity Q is such that the temperature of the liquefied natural gas is 113K and the temperature is 113K.
Assuming that the enthalpy head from the temperature to 300K at normal temperature is 48kJ / kg,

G = 5775.5 * [(300-113) / (300-77)] / 48
= 100 kg / s = 360 ton / h Therefore, by supplying the liquefied natural gas, it is possible to produce 360 tonnes of natural gas per hour in parallel with the cooling of the liquid helium.

The volume in standard state per the natural gas 1 ton is about 1250 nm ^3, low calorific value 9950kcal / Nm ³
It is. Under this condition, the amount of power generation Wg when natural gas is used as the fuel gas for the turbine is 30% for the turbine efficiency.
Then, Wg = 360 * 1250 * 9950 * 0.3 / 860 = 1562MW. Here, the cold energy utilization of the liquefied natural gas during the steady operation depends on the liquefaction refrigeration load of the superconducting energy storage device, but is approximately 10 to 50% of the power generation Wg. Is 156 to 781 MW. Therefore, for example, when the energy storage amount of the superconducting energy storage device is 100 MWh and the power generation amount is 156 MW, the storage device can absorb the entire generated power for about 40 minutes.

That is, according to the system shown in FIG. 3, it is possible to effectively use the fluctuation of the electric load and the excess cooling energy of the liquefied natural gas.

[0030]

As described above, in the present invention, the helium gas is pre-cooled by exchanging heat between the helium gas and the liquefied natural gas in the highest-temperature heat exchanger of the helium cooling device. Therefore, the helium cooling with high efficiency can be performed by simultaneously satisfying both the demands for the preliminary cooling of the helium gas and the generation of the natural gas. And
By burning the obtained natural gas and returning the energy to electric energy, there is an effect that a rational and efficient power generation system can be constructed.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a helium cooling device according to an embodiment of the present invention.

FIG. 2 is a flow sheet showing a gas turbine generator attached to the helium cooling device.

FIG. 3 shows the helium cooling device, a gas turbine generator,
1 is a configuration diagram illustrating a power generation system constructed by a superconducting energy storage device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Liquefied natural gas supply line 20 Gas turbine generator 30 Superconducting energy storage device 40 Power circuit 90 Helium cooling device 91 High pressure line 92 Low pressure line 94A Heat exchanger (heat exchanger for preliminary cooling) 94B-94F Heat exchanger 98A, 98B Expansion turbine

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yosei Sannomiya 2-1-147 Shiobara, Minami-ku, Fukuoka Kyushu Electric Power Co., Inc. (72) Inventor Hidemasa Yamamura 4-3-1 Bigocho, Chuo-ku, Osaka-shi No. Kobe Steel, Ltd. Osaka Branch Office (72) Inventor Hideo Nishida 4-1-1, Bingo-cho, Chuo-ku, Osaka City Kobe Steel Ltd. Osaka Branch Office F-term (reference) 4D047 AA03 BA03 BA10 CA07 DA17 DB05

Claims (5)

[Claims] 1. A low-pressure line for leading helium gas in a cryogenic container to the outside of the container, a compressor for compressing the helium gas led through the low-pressure line, and a helium gas discharged from the compressor. A high-pressure line for introduction into the cryogenic vessel, a multi-stage heat exchanger for performing heat exchange between the helium gas flowing through the high-pressure line and the helium gas flowing through the low-pressure line, A method for operating a helium cooling device for reducing cold helium into the cryogenic vessel, wherein the helium gas discharged from the compressor is heated to the highest temperature side. Pre-cooling is performed by exchanging heat with liquefied natural gas in an exchanger, and natural gas vaporized by this heat exchange is recovered. How to operate the helium cooling device. 2. A low-pressure line for leading helium gas in a cryogenic container to the outside of the container, a compressor for compressing the helium gas led through the low-pressure line, and a helium gas discharged from the compressor. A high-pressure line for introduction into the cryogenic vessel, a multi-stage heat exchanger for performing heat exchange between the helium gas flowing through the high-pressure line and the helium gas flowing through the low-pressure line, A helium cooling device for reducing the cooled helium into the cryogenic vessel, wherein the helium gas in the high pressure line discharged from the compressor is heated to the highest temperature. Pre-cooling is performed by exchanging heat with liquefied natural gas in the heat exchanger on the side, and natural gas vaporized by this heat exchange is burned and its energy is A power generation method using a helium cooling device, which converts the energy into electric energy. 3. The power generation method using a helium cooling device according to claim 2, wherein the cryogenic vessel is a helium storage device that cools a superconducting magnet with liquid helium and stores electromagnetic energy with the superconducting magnet. A power generation method using a helium cooling device, wherein the helium cooling device is connected to a cooling device and stores at least a part of electric energy obtained from the natural gas in the superconducting energy storage device. 4. A low-pressure line for leading helium gas in a cryogenic container to the outside of the container, a compressor for compressing the helium gas led through the low-pressure line, and a helium gas discharged from the compressor. A high-pressure line for introduction into the cryogenic vessel, a multi-stage heat exchanger for performing heat exchange between the helium gas flowing through the high-pressure line and the helium gas flowing through the low-pressure line, A helium cooling device that includes cold generation means for generating cold and reduces cooled helium into the cryogenic vessel, wherein the heat exchanger on the highest temperature side of the heat exchanger is discharged from the compressor. Is a pre-cooling heat exchanger for exchanging helium gas with liquefied natural gas, and the natural gas that has been vaporized by heat exchange in the pre-cooling heat exchanger is burned. A power generation system including a helium cooling device, comprising: a gas turbine generator that converts energy of the air into electric energy. 5. A superconducting power generation system including a helium cooling device according to claim 4, wherein the cryogenic container is connected to the helium cooling device, and a superconducting magnet is kept cool by liquid helium and electromagnetic energy is stored by the superconducting magnet. An energy storage device, and a power line for supplying electric energy generated by the gas turbine generator to the superconducting energy storage device, wherein the supplied electric energy is stored in the superconducting energy storage device. A power generation system including a helium cooling device.