JPS5810667B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a refrigeration system used in a cryogenic cooling system that uses mountain as a refrigerant.

Various refrigeration systems using H-ratio as a refrigerant have been proposed in the past, but none have been found to be satisfactory in terms of their ability to withstand continuous operation for a long period of time (several thousand hours).

In order to efficiently generate cryogenic temperatures in the liquid 1 Hg temperature range, it is necessary to house the cryogenic generator in a vacuum container (cold box) that has a heat shield at least at the liquid nitrogen temperature level.

This heat shield used liquid nitrogen or an auxiliary refrigerator.

When using liquid nitrogen, the nitrogen is used in an open cycle, so running costs are extremely high in order to provide continuous operation for several thousand hours as mentioned above. When using a refrigerator, there are drawbacks such as the cost of the auxiliary refrigerator and the operating cost rising, and the device becoming complicated.

Therefore, the present inventor first conducted research to find a heat shielding method to operate this type of cryogenic cooling equipment stably and inexpensively for several thousand hours, and found that heat intrusion into the freezing equipment and liquefaction machine There are two types of heat intrusion: heat intrusion from the outside through solid heat conduction into the internal wall of the cold box that surrounds the cold box, and heat intrusion from the inside wall of the cold box that is transmitted to the refrigerator and liquefier by radiation heat transfer.These types of heat intrusion can be effectively blocked. It has been found that the performance of refrigerators and liquefaction machines is greatly affected.

By the way, blocking heat intrusion in this type of cryogenic refrigeration equipment means, thermodynamically, that the refrigerator or liquefaction machine pumps out the invading heat to the outside with the cold generated by itself, and solid heat As understood from the principle of the Carnot cycle, pumping out the penetrating heat by conduction requires power (w) per unit amount of heat expressed by the following formula.

However, To: outside air temperature T: shield temperature, that is, the lower the shield temperature, the more power is required to cut off the intruding heat.

On the other hand, it is known that Stefan Boltzmann's theory that radiant heat increases in proportion to the fourth power of the temperature of the object facing it is expressed by the following equation.

However, σ: Radiant heat amount A: Constant T1: Surface temperature of the first object (e.g. internal surface temperature of a cold box) T2: Surface temperature of the second object (e.g. main body temperature of refrigerator and liquefier) Understand from the previous equation As can be seen from the perspective of heat intrusion due to radiation, the lower the temperature, the smaller it becomes to the point where it can be ignored.

Therefore, in view of the above-mentioned contradictory trends, the present inventors conducted further intensive research and found that the optimum shielding temperature, which is less affected by radiant heat and requires less power, is approximately 80°C, as shown in the semilogarithmic graph in Figure 1. It was found to be between 100°F and 100°F.

In FIG. 1, the vertical axis represents the required power index, the horizontal axis represents the absolute temperature, the solid line represents the relationship between the required power and the shield temperature, and the one-dot chain line represents the relationship between the required power and the radiant heat.

The present invention was made based on the above-mentioned drawbacks of the conventional art and the above-mentioned knowledge, and its purpose is to reduce running costs and provide a refrigerant that can be operated continuously for a long period of time.

The purpose of the present invention is to provide a refrigeration system that can

Next, the present invention will be explained with reference to FIG. 2, which is an embodiment.

In this case, reference numeral 1 denotes a freezing device, in which Hr gas taken out from a gas storage tank 23 is compressed to a predetermined pressure by a compressor 24, and high-pressure Ie gas is fed into the freezing device 1 into two branched flows 2a+2). It is.

The 6-way device 1 includes heat exchangers 3, 4, and 5°6 arranged in multiple stages.
．． 7, 8.9, through which the inflow flow 11 and the return flow 12 of the one branch flow 2a are passed successively in opposite directions.

Therefore, the inflow flow 11 is the one branched flow 2a and is a flow that reaches the load 19, and the return flow 12 is a return from the load 19.

In the heat exchangers 3, 4, and 10, a part of the inlet stream 11 is branched off and passed through the internal purifier 13 and the expansion engine 14, which is a cold generator, to join the inlet side of the return stream 12. There is.

Note that the internal purifier 13 has an activated carbon filter inside,
Ar in the mountains.

This removes impurities (air components) such as N2 and 02.

The heat exchanger 9 at the final stage of heat exchange of the incoming stream 11 is a Joule-Thompson (hereinafter referred to as JT).

) In the heat exchanger, the following 15 is a JT valve, which utilizes the JT effect.

In the middle of the inlet stream 11, internal purifiers 13a are provided at two locations.

Further, the other branched flow 2b is cooled to approximately 80 to 100°K by the heat exchanger 4°10, and the heat shield portion 16
After passing through the heat exchanger 10 again, the gas is fed to the gas storage tank 23 provided outside the refrigeration system 1, and is circulated through the compressor 24.

The heat shield section 16 contains the entire device described above.
It is arranged in a coil shape around the He refrigerator main body 17, and heat shields the Ie refrigerator main body.

Note that an internal purifier 13a is provided between the heat exchangers 10 and 4.

The outside of the He refrigerator main body 17 is further covered with a cold box 18 which is a vacuum container for heat insulation.

Accordingly, the inlet stream 21 exchanges heat with the return stream 12 while passing through the heat exchangers 3 to 9, gradually decreasing the temperature and increasing the purity by the internal purifier 13.

The thus cooled Hr gas undergoes isenthalpic expansion at near atmospheric pressure in the JT valve 15, whereby it partially liquefies and becomes a gas-liquid mixed state (mist).

The mist Hr exits the refrigeration device 1 and is sent to the load 19 in the next process.

The flow from the load 19 becomes the return flow 12, passes through the heat exchangers 9 to 3, and then is sent out of the refrigeration system 1.

This return flow 12 is a branch flow 2 that has exited from the refrigeration device 1.
Together with b, it enters the gas storage tank and is used again for circulation.

In addition, 20 and 21 are vacuum pumps, and cold box 1
8. Degas the He channel in the refrigeration device 1.

Next, the operation of the refrigeration system 1 having the above configuration will be explained.

Cold box 1 is removed by vacuum pumps 20 and 21.
8. Deaerate the inside of the Hr channel to remove impurities.

Continuing, high-pressure Hr purified by mainly removing 2002 parts of H2O in a previous step, for example, a gas purification device (not shown)
Gas is supplied to the refrigeration device 1 as two branched flows 2a, 2b.

Here, it is assumed that the Hr gas is at 3,000 psi and at a pressure of 15 to 20 atm.

In the refrigeration system 1, the inlet stream 11 and the branch stream 2b are cooled to approximately 80°K by means of the heat exchangers 3, 4, 10.

Cooling is provided by a return flow 12 that is cooled by an expansion engine 14.
By heat exchange with.

Therefore, the He refrigerator main body 17 is heat shielded by the heat shield portion 16 cooled to about 80°K.

Furthermore, inlet stream 11 is cooled to approximately 5°K by heat exchangers 5-9.

Then, the body is cooled to 4.4°K by the JT valve 15, and a portion of the Hr gas is directed down the armpit to form a mist state.

Hr in a mist state is sent out from the refrigeration device 1, passes through a load 19 in the next step, becomes a return flow 12, and returns to the refrigeration device 1 again.

The return stream 12 then passes through the heat exchangers 9-3 while cooling the inlet stream 11 and enters the gas storage tank as described above for repeated circulation.

Note that when starting the operation of the refrigeration system 1, a pre-cooling line for liquid nitrogen (approximately 80°K) is provided as shown by the broken line in the figure.
If the refrigerator main body 17 is heat shielded, the cooling effect, such as shortening of the precooling time, will be further improved.

As is clear from the above explanation, according to the present invention, He
This e-freezing machine has an optimal shield temperature that requires less power for the main body shield, and utilizes the excess capacity of the He circulation flow path, which simplifies the equipment and reduces He consumption. This reduces running costs and is particularly effective for long-term continuous operation.

In addition, since the valves, which are room-temperature operating parts, are not exposed to extremely low temperatures at all, heat loss is small and cooling performance is good.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the relationship between shield temperature and required power, and FIG. 2 is a system diagram of a refrigeration system according to the present invention. 1...refrigeration device, 2a, 2b...branched flow, 3...10...heat exchanger, 11...
... Inflow flow, 12 ... Return flow, 13 ...
... Internal purifier, 14 ... Expansion engine, 1
5... Joule Thomson valve, 16...
Heat shield part, 17...He refrigerator body, 18
...Cold box, 19...Load.

Claims (1)

[Claims] A refrigeration system that uses IHe as a refrigerant and constitutes a closed cycle with a compressor, a refrigerator main body, and a gas storage tank. The exchanger and the Joule-Thompson valve, and one of the branched flows of the high-pressure H-ratio gas flow path are passed through the heat exchanger and the Joule-Thompson valve in this order to form an inflow flow leading to the load, while in contrast to the above, heat exchange is performed. piping that formed the return flow from the load passed through the heat exchanger and a portion HH from the inflow flow exiting at least one or more of the heat exchangers.
The refrigeration system is formed by passing the gas through an internal purifier and a refrigeration generator to pipes that join the return flow, and passing the other branched flow through a part of the heat exchanger to cool it to about 80 to 1000 K. A refrigeration device characterized by comprising a heat shield part of the machine body.