JP4563269B2 - Refrigeration capacity control device for turbine-type refrigerator - Google Patents

Description

The present invention relates to refrigerating capacity system GoSo location of the turbine refrigerator for generating cold by turbine expansion.

Conventionally, a helium refrigerator has been used to bring liquid nitrogen in a cryostat (low temperature vessel: liquid nitrogen storage tank) into a subcooled state.
By the way, in order to keep the temperature of the refrigerant in the refrigerator in which the thermal load fluctuates constant, a refrigerating capacity adjustment mechanism of the refrigerator is required. Therefore, regardless of fluctuations in the refrigeration load, the inlet pressure of the expander is detected and the inlet flow rate of the expander is controlled based on this detected pressure in order to operate the expander for generating cold constantly and efficiently. At the same time, the JT valve (Joule Thomson valve: a valve that works to adiabatic expansion of the fluid by giving a large throttle to the flow path and lowering the temperature of the fluid to a low temperature) makes the refrigerant on the outlet side of the low-pressure line more than the expander. The refrigerant is supplied to the inlet side of the high pressure side heat exchanger, the inlet temperature of the expander is detected, and the refrigerant supply amount on the outlet side of the expansion valve is controlled so that the inlet temperature approaches a predetermined target temperature. An operation control method of a liquefaction refrigeration apparatus has been proposed (Patent Document 1 below).
JP-A-6-265230

When an alternating current is passed through a high-temperature superconducting coil that is immersed and cooled in liquid nitrogen in the cryostat, a thermal load is generated due to an AC (alternating current) loss. Since this thermal load varies depending on the amount of current, as described above, in order to keep the cooling temperature of the cryostat constant, it is necessary to adjust the refrigerating capacity of the refrigerator.
At present, turbine-type refrigerators are mainly MW class large-capacity types, and as described above, technologies of this class corresponding to load fluctuations with variable expansion capacity have been reported (Patent Document 1). ). However, for example, in a 1 to 5 kW class small-sized turbine refrigerator for a main transformer for a railway vehicle, since the turbine blades are reduced and the turbine rotational speed is increased, a method of making the expansion capacity variable is adopted. That is said to be difficult. Further, in the method of changing the turbine inlet pressure, the refrigeration capacity fluctuates severely and cannot follow a load fluctuation of several watts.

In view of the above situation, the present invention can accurately adjust the refrigeration capacity of a refrigerator without changing the inlet pressure and capacity of a turbine expander that is generally operated in a steady state with a constant refrigeration generation capacity. and to provide a refrigerating capacity system GoSo location of high refrigerating capacity turbine refrigerator possible.

In order to achieve the above object, the present invention provides
[ 1 ] In a refrigeration capacity control apparatus for a turbine-type refrigerator, a cryostat having a heat load of 1 to 5 kW, in which a refrigerant having a condensation heat exchanger is enclosed, and one end of the condensation heat exchanger are connected A JT valve connected to the other end of the condensation heat exchanger, a first heat exchanger connected in series to the JT valve, and a first connected in series to the JT valve a turbine expander heat exchanger is connected in parallel, and a second heat exchanger connected to the first heat exchanger connected to the JT valve in series to the turbine expander, the second A compressor connected in parallel to the heat exchanger, an automatic bypass valve connected in parallel to the compressor, a temperature sensor provided in the cryostat, and the JT based on an output signal from the temperature sensor P for adjusting the degree of opening of the valve Characterized by comprising a D controller.

[ 2 ] In the refrigeration capacity control device for a turbine-type refrigerator according to [ 1 ], liquid nitrogen is used as the refrigerant.

According to the present invention, the following effects can be achieved.
(1) Generally, the refrigeration capacity of the refrigerator can be adjusted accurately without changing the inlet pressure and capacity of a turbine expander that is operated in a steady state with a constant refrigeration generation capacity.
(2) JT expansion (Joule Thompson expansion: a phenomenon in which when the gas is expanded below a certain temperature, the temperature of the gas decreases), by using it for the purpose of raising the temperature, It is suitable for a 5 kW class small turbine refrigerator.

  In order to keep the temperature of the refrigerant in the cryostat where the thermal load fluctuates constant, a refrigeration capacity adjustment mechanism for the refrigerator is required. Therefore, a JT valve is provided in parallel on the high-pressure inlet side of the turbine expander, and the helium gas that is adiabatic and free-expanded is merged with gas helium cooled by the turbine expansion to adjust the refrigeration capacity.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a configuration diagram of a refrigeration capacity control system for a turbine-type refrigerator showing an embodiment of the present invention.
In this figure, 1 is a cryostat (low temperature vessel: subcooled liquid nitrogen storage tank), 2 is a condensation heat exchanger provided in the cryostat 1, 3 is a temperature sensor provided in the cryostat 1, and 4 is a condensation heat exchanger 2. A JT valve (needle valve) 5 connected to the first end, a turbine expander connected to the first end of the condensation heat exchanger 2 and connected in parallel with the JT valve (needle valve) 4, Reference numeral 6 denotes a first heat exchanger connected to the second end of the condensation heat exchanger 2 and the JT valve (needle valve) 4. Reference numeral 7 denotes the first heat exchanger 6 and the JT valve (needle valve) 4. The second heat exchanger connected to the first heat exchanger 6 and the turbine expander 5 via 8, 8 is a compressor connected in parallel with the second heat exchanger 7, and 9 is the compressor 8. Automatic bypass valve 10 connected in parallel, 10 is connected to temperature sensor 3 This is a PID controller (Proportional integral and Differential: feedback control in which the input value is controlled by three elements of deviation between the output value and the target value, its integration, and differentiation), and the output from this PID controller 10 A valve (needle valve) 4 is controlled. A is a cold box and B is a room temperature region.

  The present invention is generally provided in a branch line by branching the discharge flow rate of a compressor in parallel with an expansion line without changing the inlet pressure and capacity of a turbine expander that is generally operated in a steady state with a constant refrigeration generation capacity. By adjusting the opening of the JT valve (needle valve) and combining it with the low-temperature gas after turbine expansion before entering the condensation heat exchanger, the subcooled liquid nitrogen is Temperature control can be achieved.

Further, it is possible to easily control the temperature of a turbine refrigerator, which is said to be difficult to adjust the refrigerating capacity from a small size to a large size, with respect to load fluctuations.
In addition, this invention is not limited to the said Example, Based on the meaning of this invention, a various deformation | transformation is possible and these are not excluded from the scope of the present invention.

  The method and apparatus for controlling the refrigeration capacity of a turbine refrigerator of the present invention is suitable for a 1 to 5 kW class small turbine refrigerator for a railway vehicle main transformer.

It is a block diagram of the refrigerating capacity control system of the turbine type refrigerator which shows the Example of this invention.

1 Cryostat (Cryogenic container: Subcooled liquid nitrogen storage tank)
2 Condensation heat exchanger 3 Temperature sensor 4 JT valve (needle valve)
DESCRIPTION OF SYMBOLS 5 Turbine expander 6 1st heat exchanger 7 2nd heat exchanger 8 Compressor 9 Automatic bypass valve 10 PID controller A Cold box B Room temperature region

Claims (2)

A small turbine with a thermal load of 1-5 kW,
(A) a cryostat in which a refrigerant having a condensation heat exchanger is enclosed;
(B) a JT valve connected to one end of the condensing heat exchanger;
(C) a first heat exchanger connected to the other end of the condensing heat exchanger and connected in series to the JT valve;
( D ) a turbine expander to which a first heat exchanger connected in series with the JT valve is connected in parallel;
( E ) a first heat exchanger connected in series with the JT valve and a second heat exchanger connected to the turbine expander;
(F) a compressor connected in parallel to the second heat exchanger,
( G ) an automatic bypass valve connected in parallel to the compressor;
( H ) a temperature sensor provided in the cryostat;
(I) A refrigeration capacity control device for a turbine-type refrigerator, comprising: a PID controller that adjusts an opening degree of the JT valve based on an output signal from the temperature sensor. 2. The refrigeration capacity control device for a turbine type refrigerator according to claim 1 , wherein liquid nitrogen is used as the refrigerant.

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