KR100314947B1 - Helium (HE) Liquefied Refrigerator - Google Patents

Abstract

The present invention enables efficient capacity control of a group of variable speed vibration compressors enclosed according to load variation, and includes an independent variable speed gas turbine power generation system as a driving power source, and improves continuous operation. A helium liquefied refrigeration system having a variable frequency power generation system for a compressor, which provides a helium liquefied refrigeration system that enables the use of cold heat and waste heat recovery, and has a high-efficiency capacity control. The variable frequency power generation system 33 which consists of the power generation part 30, the adsorption freezer 31 which is a chemical refrigerator, and the fuel supply part 35 is comprised.

Description

Helium liquefied chiller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large capacity helium liquefied chiller used for superconducting devices such as superconducting transmission, storage, fusion power generation, and linear motor cars. will be.

Helium liquefied refrigeration machine is a compressor by adiabatic expansion of the boosted helium in the expansion turbine to generate a cold, heat exchange with the return helium to cool, and also by adiabatic free expansion in the Joule-Thomson valve (JT valve) It is configured to form a cold heat source of liquefied helium from the quenched helium, and to return to the compressor after the necessary refrigeration.

As the refrigerator for producing the liquefied helium, for example, the helium liquefied refrigeration apparatus shown in Fig. 3 of Japanese Patent Laid-Open No. 5-797l9 is known.

That is, such a helium liquefied refrigeration apparatus includes a compressor 68, a precooled heat exchanger 60, heat exchangers 61, 62, 63, 64, a liquefied nitrogen cooler unit 69, And a helium tank 66 for storing liquefied helium, and a high pressure helium gas supply liquefaction passage formed to be introduced into the helium tank 66 through each heat exchanger from the discharge side of the compressor 68. (50), a reflux return flow path (51) of low pressure helium gas formed to penetrate each heat exchanger from the helium tank (66) to the suction side of the compressor (68), and the supply liquefaction flow path (50) and reflux return A cold bypass flow path 52 which is connected to the flow path 51 via expansion turbines 53 and 54, and a JT expansion valve 50a provided at the end of the supply liquefaction flow path; For example, it comprises a cooling load 65 having a superconducting magnet built therein and receiving liquid helium from the helium tank 66.

In the liquefied refrigerator having the above configuration,

Compressor 68 is a forward displacement compressor that repeats cycles of suction, compression and discharge by changing the volume of space by simple rotational movement of two rotors. Possible oiled skew compressors are used.

The high pressure helium gas compressed by the compressor 68 is first introduced into the precooling heat exchanger 60 through the supply liquefaction flow path 50, and from the liquid nitrogen cooling device 60 in the heat exchanger 60. Precooled by the heat of vaporization of liquid nitrogen LN ₂ .

Subsequently, the mixture is slowly cooled via the heat exchangers 61, 62, 63, and 64, and finally helium in a gas-liquid two-phase state by free expansion of the JT expansion valve 50a. Thus, the helium tank 66 is introduced.

On the other hand, the low-intake low-temperature helium gas vaporized in contact with the cooling load 65 and the helium tank 66, the heat exchanger (64), (63), (62), (61) through the reflux return flow path (51). And reflux to the suction side of the compressor 68 via the precooling heat exchanger 60, and liquefy feed through the heat exchangers 64, 63, 62, 61 and the precooling heat exchanger 60. The countercurrent heat exchange is performed with the high pressure helium gas in the flow path 50 to cool the high pressure helium gas.

In addition, a part of the high-pressure helium gas in the supply liquefaction flow path 50 is branched by the cold bypass flow path 52, and after the cold air is generated by adiabatic expansion via the expansion turbines 53 and 54, the heat exchanger Through 62, the heat exchanger 64 and the heat exchanger 63 of the reflux return flow path 51 are joined together to form a cold cooling source of the high-pressure helium gas, and the heat exchanger 63 The high pressure helium gas in the supply liquefaction flow path is cooled.

The cold-cooled high-pressure helium gas expands freely through the JT expansion valve 50a to become helium in a gas-liquid two-phase state, and is introduced and stored in the helium tank 66.

In addition, the level detection element 67 detects the appropriate liquid level of the helium tank 66, and the nozzle opening degree control section 56 makes it possible to control the nozzle opening degree of the expansion turbines 53 and 54, It is to cope with fluctuating refrigeration load.

However, in the case of the control means, the control energy loss is high, and there is also a problem of overheating the expansion turbine. For this reason, a variable capacity deep-cooled expansion turbine downstream of the supply liquefaction flow passage is installed side by side in the flow passage and operated by liquid level detection installed in the helium tank, so that the amount of cold generation appropriate for the expansion turbine installed in the cold bypass flow passage of the previous stage is provided. Means for responding to varying refrigeration loads have been proposed to maintain the pressure.

However, since the development of nuclear fusion power generation is inevitable, the development of a large superconducting magnet is inevitable, and this requires a large-capacity helium liquefied chiller necessary for cooling the magnet, and furthermore, the emergence of a refrigerator having reliability and continuous operation is strongly desired. It is a situation.

As the compressor that determines the reliability and continuous operation of the refrigerator, as described in the conventional example shown in FIG. 3, a lubricated screw compressor is used, but a plurality of oil injection type multi-stage compressors are used according to the size of the refrigerator. Furthermore, since there is a problem of environmental pollution due to leakage of oil from the shaft seal part of the compressor and a problem of inhibiting continuous operation of the helium liquefied chiller due to atmospheric mixing from the shaft seal part, sealing of the screw compressor is required. In particular, the sealing of a plurality of multistage compressors is an important task for efficiency.

On the other hand, even in view of the safety problems used in the fusion reactor, it is also indispensable to secure the planned operation in order to avoid the operation stop due to the power failure of the helium liquefied refrigerator used in these, and to continue the operation.

In addition, for efficient operation, it is necessary to control the capacity of the compressor that can cope with variations in the refrigeration load.

In summary, about the compressor,

1, The sealing of a plurality of multistage compressors is required from the problems of leakage and air mixing.

2. Continuous operation is required even in case of power failure due to the problem of safe operation of load.

3. Capacitance control is available in response to changes in load.

In order to solve the above-mentioned problem, in particular, the direct operation of the compressors 72 and 73 by the engine 78 shown in FIG. 4 (B) has been proposed and performed. It is thought that it is not suitable in terms of sealing of a term.

In order to solve the above-mentioned claims 3 and 1, conventionally, the drive induction machine Mc of the electric multistage compressors 70 and 71 by the inverters 74 and 75 shown in Fig. 4A. ) And (Md) allow variable speed operation by variable frequency so that capacity can be controlled.

Therefore, in the case of the variable frequency operation by the inverter, it is possible to solve the problem of capacity control in a sealed atmosphere, but there are problems as follows. In other words,

1. The inverter is low in reliability, and the inverter is often damaged in the event of an overload or an unexpected situation.

2. In the inverter drive compressor, even if there is no problem in the main body of the compressor, there is a possibility that the whole compressor may be stopped due to an abnormality or failure of the inverter.

3. For this reason, it is necessary to install an inverter fault diagnosis function device and a system to be replaced by constant speed operation by the grid power supply.

4. There is a problem of reducing efficiency due to inverter loss or malfunctioning of measurement-related equipment due to electrical noise caused by inverted waveform, and then falling into control.

In view of the above problems, the present invention can enable efficient capacity control of a hermetic electric compressor group against load fluctuations, and is equipped with a variable frequency power generation system by an independent variable speed gas turbine, and at the same time a combustion system of the apparatus. The cold heat exchanger provided in the present invention enables the use of the vaporized heat of liquefied natural gas and the waste heat recovery of the combustion gas to provide an efficient helium liquefied refrigerator.

During the enclosed sealing including the drive motors of a plurality of multistage compressor groups, which have been conventionally required for the compressor, continuous operation is possible regardless of the power failure, which is a problem in safe operation of the load, and at the same time Capacitive control is possible in response to fluctuations, and the gas turbine power generation system is installed as an independent power source for supplying variable frequency power, and is a fully enclosed variable speed electric screw multistage compressor operating under the supply of variable frequency power by the independent power supply. A variable frequency power generation system for compressors that efficiently operates under refrigeration loads by providing a group to cope with refrigeration loads and to enable use of cold heat installed in the combustion system of the gas turbine power generation system. The purpose is to provide a helium liquefied refrigeration machine equipped with a system.

1 is a schematic configuration diagram of a helium liquefied chiller having a variable frequency power generation system for a compressor according to the present invention,

2 is a schematic configuration diagram of a variable frequency power generation system of FIG. 1,

3 is a schematic configuration diagram of a conventional helium liquefied refrigerator,

4 is a view showing a driving method of a conventional compressor group,

(A) shows the case of inverter driving,

(B) shows the case of engine driving.

* Description of the symbols for the main parts of the drawings *

10 ...... Supply liquefied flow path 10a ..... JT expansion valve

11 ...... Reflux return euro 12 ...... Cold bypass euro

12a ..... Expansion Turbine 13 ...... Helium Liquefied Refrigerator

14 ...... Compressor Group 16 ..... Liquefied Helium Tank

15a, 15b ..... Totally sealed variable speed electric screw multistage compressor

17 ....... Cooling load 20,21 .... Precooling heat exchanger

22,23,24 ... Heat exchanger 30 .......

30b ...... 3 phase variable frequency power 30e ......

30d ...... Cistern Power 31 ....... Adsorption Chiller

31a ...... Heat source side 31b ...... Cooling side

35 ....... fuel supply 36 ....... LNG tank

37 .., .... Warmer 38 ....... Vaporizer

41 ....... Compressor 42 ....... Combustor

43 ....... Gas turbine 45 ....... Frequency converter

46 ....... Fuel control unit 47 .......

The liquefied refrigeration machine of the present invention for achieving the above object is a compressor group for compressing liquefied helium gas, a helium tank, a cooling load supplied with helium from the helium tank, and a helium tank at the discharge side of the compressor group. A liquefaction flow path for supplying high pressure helium gas, a reflux return flow path for refluxing low-pressure low-temperature helium gas from the helium tank to the suction side of the compressor group, and a plurality of stages penetrating through the supply liquefaction flow path and the reflux return flow path respectively. In the liquefied chiller having a plurality of heat exchangers,

The compressor group comprises an electric screw multi-stage compressor group, and controls the rotation speed in response to the load by using a separately installed gas turbine power generation system as a power source, and is provided to another cooling heat medium on the compressor discharge side of the heat exchanger of the plurality of stages. And at least one precooling heat exchanger provided with a heat exchange path, wherein the fuel supplied to the gas turbine is supplied through the heat exchange path of the precooling heat exchanger.

In the helium liquefied refrigeration machine of the present invention, the gas of the gas turbine is vaporized in the heat exchange path of the precooling heat exchanger to perform precooling of the helium gas discharged from the compressor passing through the precooling heat exchanger using the heat of vaporization.

Therefore, according to the present invention, the variable frequency gas turbine power generation system provided separately from the helium liquefied chiller enables continuous high efficiency driving of the variable speed electric screw multistage compressor, and the capacity control is made in response to the change in the refrigeration load. It becomes possible. That is, the drive inductors of each of the electric screw multistage compressor groups are driven at the same rotational speed corresponding to the load requirements by introducing a homogeneous waveform corresponding to the combination of the compressor groups and by introducing an optimum frequency power corresponding to the load. It is possible to achieve optimum efficiency.

In addition, as described above, the independent stable power supply equipment can be used to establish continuous operation.

In addition, a cold heat conversion unit is provided on the exhaust side and the fuel intake side of the exhaust gas in the combustion system of the variable frequency gas turbine power generation system, and the cold heat obtained from the conversion unit is introduced into the precooling heat integrator of the helium refrigerator, thereby changing the melt- varying type. It is possible to pre-cool high-pressure helium gas from the compressor group, and it is possible to operate the efficient helium liquefied chiller by the organic combination of the effective use of the exhaust heat of the gas turbine power generation system and the cooling heat of the natural gas used for the fuel gas. Done.

The present invention also provides a compressor group for compressing liquefied helium gas, a helium tank, a cooling load supplied with helium from the helium tank, and a supply liquefied flow path for supplying high pressure helium gas from the discharge side of the compressor group to the helium tank. And a reflux return passage for refluxing the low pressure low temperature helium gas from the helium tank to the suction side of the compressor group, and a plurality of heat exchangers installed in a plurality of stages through the supply liquefaction flow path and the reflux return flow path, respectively. In that,

The compressor group comprises an electric screw multistage compressor group, controls the rotational speed corresponding to the load by using a separately installed gas turbine power generation system, and installs a chemical refrigerator operated by using waste heat of the gas turbine power generation system. At the same time, at least one precooling heat exchanger provided with a heat exchange path by another cold heat medium on the compressor discharge side of the heat exchanger of the recovery means, and circulates the heat exchange path of the precooling heat exchanger with the cold water obtained from the chemical freezer. And precooling the helium gas discharged from the compressor passing through the precooling heat exchanger using the cold water.

In addition, the present invention is the fuel of the gas turbine is liquefied natural gas, vaporize the liquefied natural gas in the heat exchange path of the precooling heat exchanger, and performs the pre-cooling of the discharge helium gas of the compressor passing through the precooling heat exchanger through the heat of vaporization. It is.

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

However, the dimensions, shapes, relative positions, and the like of the constituent parts described in the present embodiment are not intended to limit the scope of the present invention to them unless otherwise specified, and are merely illustrative examples.

1 is a schematic configuration diagram of a helium liquefied chiller having a variable frequency power generation system for a compressor according to the present invention, Figure 2 is a schematic configuration diagram of a variable frequency power generation system.

As shown in FIG. 1, the helium liquefied refrigeration machine provided with the variable frequency power generation system for compressors of this invention is comprised from the helium liquefied refrigeration machine 13 and the variable frequency power generation system 33. As shown in FIG.

The variable frequency power generation system 33 includes a gas turbine power generation unit 30, a adsorption freezer 31, which is a chemical refrigerator, and a fuel supply unit 35.

The helium liquefied refrigeration machine (13) includes a hermetic compressor group (14) consisting of a hermetically sealed variable speed electric screw multistage compressor (15a, 15b), a liquefied helium tank (16), a cooling load (17) that is a superconducting magnet, and The supply liquefaction flow path 10 for supplying the high pressure helium gas from the discharge side of the compressor group 14 to the liquefied helium tank 16, and the low pressure low temperature helium gas from the liquefied helium tank 16 are connected to the compressor group 14. Reflux recirculation flow path 11 refluxing to the suction side, reflux heat exchangers 20, 21, heat exchangers 22, 23, 24 and reflux from the intermediate end of feed liquefaction flow path 10. It consists of the cold bypass flow path 12 and the JT expansion valve 10a which are joined between the upstream heat exchanger 22 and 23 of the flow path 11 via the expansion turbine l2a.

The totally sealed variable speed electric screw multi-stage compressors (15a) and (15b) are respectively variable speed motors for preventing environmental pollution due to oil leakage from the shaft seal portion or preventing continuous operation due to atmospheric mixing from the shaft seal portion. The interior is sealed.

In addition, in order to achieve miniaturization and geocoating, low and high stages are assembled on one shaft, or low and high stages are assembled on both shafts using both shaft motors.

In addition, injection oil type screw flow compressors capable of volume control with little change in efficiency with respect to rotational changes are used.

The driving motors Ma and Mb are constituted by three-phase induction motors, and are supplied with three-phase variable frequency power from the variable frequency power generation system 33, so that the rotational speed can be changed and the load is required. A configuration capable of controlling the capacitance in response to the signal is provided.

In the precooling heat exchanger 20, the cooling heat generated in response to the cold heat of the low pressure low temperature helium gas refluxed through the reflux return flow passage 11, the vaporization heat of LNG described later, and the cooling side of the adsorption freezer 31 ( The high-pressure helium gas flowing through the supply liquefaction flow passage is subjected to countercurrent heat exchange to precool the cold heat output from 31b).

In the pre-cooling heat exchanger 21, the high-pressure helium gas flowing through the supply liquefaction flow passage in response to the cold heat of the low pressure low temperature helium gas refluxed through the reflux return flow passage 11 and the vaporization heat of LNG described later. The counter current is preheated by heat exchange.

In the cold heat exchangers 23 and 24, the high pressure helium gas flowing through the supply liquefaction flow passage is precooled by countercurrent heat exchange with respect to the cold heat of the low pressure low temperature helium gas refluxed through the reflux return flow passage 11.

In the heat exchanger 22, the high pressure which is adiabatically expanded by an expansion turbine 12a provided on the cold bypass flow passage 12 branched from the middle of the supply liquefaction flow passage 10 and is cooled to a cold state. The high-pressure helium gas flowing through the supply liquefaction flow path 10 is countercurrently heat-exchanged and cooled to the vicinity of the liquefaction against cold cold heat generated by joining the low-pressure low-temperature helium gas flowing through the reflux return flow path.

In addition, the JT expansion valve 10a is an adiabatic expansion valve, and is sequentially precooled through the precooling heat exchangers 20 and 21 as described above, and further, in the order of the heat exchangers 22, 23, and 24. The high-pressure helium gas flowing through the supply liquefaction flow path 10 which is cooled sequentially and immediately before the liquefaction bar is liquefied by adiabatic expansion, and becomes a gas-liquid two-phase state to be supplied and stored in the liquefied helium tank 16.

In this case, the cooling load 17 can receive the supply of liquefied helium from the liquefied helium tank 16 through the flow path 16a. In addition, the low-temperature helium gas vaporized as a result of contacting the cooling load 17 is stored in the upper portion of the helium tank 16 through the flow path 17a, and becomes a low-temperature low-pressure helium gas through the reflux return flow path 11 through the compressor group. A circulation path is formed to be returned to the suction side of (14).

The variable frequency power generation system 33 includes a gas turbine power generation unit 30, an adsorption freezer 31, which is a chemical refrigerator, and a fuel supply unit 35.

As shown in FIG. 2, the gas turbine power generation unit 30 includes a compressor 41 for inhaling and compressing air, and compressed air and fuel (LNG vaporized gas) 30a formed by the compressor 41. The combustor 42 which performs combustion by using the gas turbine 43, the frequency converter 45, the fuel control unit 46, and the operation unit 47, which are driven as combustion air formed in the combustor 42. It is configured to include.

In addition, the frequency converter 45, the compressor 41, and the gas turbine 43 are set on the same axis.

The frequency converter 45 is such that the three-phase variable frequency power 30b corresponding to the rotation speed of the gas turbine 43 can be obtained by the AC excitation by the system power supply 30d.

In order to operate the variable speed gas turbine 43, the calculation unit 47 inputs the load request signal Pd from the cooling load 17 and the atmospheric temperature T detected by the atmospheric temperature detector to calculate the required fuel amount to control the fuel control unit. In 46, the required fuel is controlled and supplied from the frequency converter 45 to the inductors Ma and Mb of the compressor group 14, which are three-phase variable frequency power corresponding to the load request signal. Thus, the capacity control of the compressor group 14 is enabled.

Since the adsorption freezer (31), which is a chemical refrigerator, supplies hot water (30e) formed by the exhaust gas of the gas turbine power generation unit (30) to the heat source side (3la) to obtain cooling heat from the cooling side (31b). As described above, the cold heat obtained at the cooling side 31b is supplied to the precooling heat exchanger 20 to enable precooling of the high pressure helium gas flowing through the supply liquefaction flow path 10.

The fuel supply part 35 is comprised from the LNG tank 36, the heating part 37, and the vaporization part 38 for the precooling heat generation in the precooling heat exchanger 20,21.

When the amount of LNG supplied to the gas turbine 43 is more than the amount of vaporization in the vaporization part 38 of the precooling heat exchanger 20 and 21, the heating part 37 forcibly vaporizes LNG by gas It is set as the structure which ensures the fuel suitable supply amount to the turbine 43.

In addition, the cold heat formed in the adsorption freezer 31 is used for precooling the high pressure helium gas which flows through the supply liquefaction flow path 10, and the amount of supply LNG to the gas turbine 43 in the vaporization part 38 of a precooling heat exchanger is carried out. If less than the amount of vaporization, the precooling load is reduced to achieve balance.

By precooling in the precooling heat exchanger (20), (21) by the cold heat generated by the exhaust gas of the gas turbine power generation unit 30 and the cold heat generated from the vaporization unit 38 of the fuel supply unit (35). This eliminates the need for precooling by vaporization of liquid nitrogen found in conventional systems.

As described above, the present invention is to improve thermal efficiency by organically combining the devices in the system between the adsorption freezer (31) and the fuel supply unit (35).

The variable frequency power generation system installed separately for the helium liquefied chiller enables efficient driving of the hermetic screw screw compressor group, and achieves the same frequency power with a homogeneous waveform corresponding to the combination of the compressor groups. Introduced, the variable speed power screw multistage compression group can be driven at the optimum rotational speed corresponding to the load demand, and the optimum efficiency can be achieved.

Moreover, the continuous operation can be secured by the stable independent power supply system as described above.

In addition, the variable frequency power generation system is composed of a gas turbine power generation unit using an LNC, a fuel supply unit, and a chemical refrigeration unit, and by using cold heat corresponding to LNG vaporization heat and cooling heat using waste heat for precooling high pressure helium gas, The thermal efficiency of the system can be attained.

In addition, there is no need for a conventional precooled liquid nitrogen.

Claims (4)

A compressor group for compressing liquefied helium gas, a helium tank, a cooling load supplied with helium from the helium tank, a supply liquefied flow path for supplying high pressure helium gas from the discharge side of the compressor group, and a helium tank; In the liquefied refrigeration refrigerator having a reflux return flow path for refluxing the low-pressure low-temperature helium gas to the suction side of the compressor group, and a plurality of heat exchangers installed in a plurality of stages through each of the supply liquefaction flow path and the reflux return flow path, The compressor group comprises an electric screw multi-stage compressor group, and controls the rotation speed in response to the load by using a separately installed gas turbine power generation system as a power source, and is provided to another cooling heat medium on the compressor discharge side of the heat exchanger of the plurality of stages. And at least one precooling heat exchanger provided with a heat exchange path, wherein the fuel supplied to the gas turbine is supplied through a heat exchange path of the precooling heat exchanger. The helium liquefied chiller of claim 1, wherein the fuel of the gas turbine is vaporized in a heat exchange path of the precooling heat exchanger, and the preheating of the helium gas discharged from the compressor passing through the precooling heat exchanger is performed using the heat of vaporization. . The fuel of the gas turbine is liquefied natural gas, and vaporizes the liquefied natural gas in a heat exchange path of the precooling heat exchanger, and precools the discharged helium gas of the compressor passing through the precooling heat exchanger through the heat of vaporization. Helium liquefied chiller, characterized in that. A compressor group for compressing liquefied helium gas, a helium tank, a cooling load supplied with helium from the helium tank, a supply liquefied flow path for supplying high pressure helium gas from the discharge side of the compressor group to a helium tank, and a helium tank. In a helium liquefied refrigeration machine having a reflux return flow path for refluxing low-pressure low-temperature helium gas to the suction side of the compressor group, and a plurality of heat exchangers installed in both stages through the supply liquefaction flow path and the reflux return flow path, respectively. The compressor group comprises an electric screw multistage compressor group, and controls the rotational speed corresponding to the load by using a separately installed gas turbine power generation system as a power source, and installs a chemical refrigerator operated by using waste heat of the gas turbine power generation system. At the same time, at least one precooling heat exchanger having a heat exchange path by another cold heat medium is installed on the compressor discharge side of the plurality of heat exchangers, and the cold water obtained from the chemical freezer is circulated through the heat exchange path of the precooling heat exchanger. And precooling the helium gas discharged from the compressor passing through the precooling heat exchanger using the cold water.