Low-temperature gas generator
The low-temperature gas generator addresses white smoke and inefficient energy use by integrating heat exchangers to vaporize liquefied gas and heat exhaust gas, optimizing gas supply and eliminating white smoke without additional systems, thus reducing costs and space.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NIPPON SANSO CORP
- Filing Date
- 2025-01-08
- Publication Date
- 2026-07-21
AI Technical Summary
Existing low-temperature gas generators release low-temperature gas directly into the atmosphere, causing white smoke due to water vapor condensation, risking blower malfunction and inefficient utilization of cold energy, and require separate heat sources for effective smoke prevention, increasing costs and space requirements.
A low-temperature gas generator with a first and second heat exchanger configuration that vaporizes low-temperature liquefied gas and heats exhaust gas, utilizing the cold energy to cool mixed gas and prevent white smoke without additional heat sources, using flow and temperature controls to optimize gas supply.
Effectively utilizes exhaust gas cold energy, reduces low-temperature liquefied gas demand, prevents white smoke, and minimizes costs and space by integrating heat exchangers without separate systems.
Smart Images
Figure 2026119937000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a low-temperature gas generator, and more particularly to a low-temperature gas generator that generates a low-temperature gas for cooling an object to be cooled and enables prevention of white smoke when exhausting the exhaust gas after cooling the object to be cooled.
Background Art
[0002] As a device when a low-temperature gas (below -60°C, below -120°C in a low-temperature specification) that cannot be obtained by a mechanical refrigerator such as a Freon refrigerator that can obtain a low-temperature gas of about -50°C (about -100°C even in a low-temperature specification) is required, a low-temperature gas generator (low-temperature gas supply device) described in Patent Document 1 is known.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0004] [[ID=e="38"]] Although the low-temperature gas generator of Patent Document 1 does not require a rotating machine such as a refrigerant compressor and is characterized by a simpler configuration compared to a mechanical refrigerator, the generated low-temperature gas is directly released into the atmosphere after being cooled by the heat medium of the heat medium cooling device. Since the gas to be released is also in a low-temperature state close to the object to be cooled, white smoke is generated. However, the white smoke generated by condensing the water vapor in the atmosphere is not aesthetically pleasing. Even when locally exhausting with a blower, there is a risk that water droplets will accumulate in the blower, causing malfunction or deterioration of the blower. In addition, the cold heat of the exhausted exhaust gas (low-temperature gas) cannot be effectively utilized and is wasted.
[0005] As shown in Patent Document 2, there are examples of installing a separate heat exchanger to prevent white smoke, but this utilizes a separate heat source, resulting in high equipment costs and ineffective utilization of the cold energy of the released low-temperature gas.
[0006] Therefore, the present invention aims to provide a low-temperature gas generator that effectively utilizes the cold energy of exhaust gas without providing a separate heat source, reduces the amount of low-temperature liquefied gas required, and prevents the generation of white smoke. [Means for solving the problem]
[0007] To achieve the above objective, the present invention provides a low-temperature gas generator that generates a low-temperature gas for cooling an object to be cooled and exhausts exhaust gas after the object has been cooled, comprising: a first heat exchanger that generates a vaporized gas by vaporizing a low-temperature liquefied gas through heat exchange; and a second heat exchanger that raises the temperature of the exhaust gas through heat exchange, wherein the second heat exchanger exchanges heat between a mixed gas, which is a mixture of a gas that is in a gaseous state at a temperature higher than the boiling point of the low-temperature liquefied gas and the vaporized gas, and the exhaust gas, thereby cooling the mixed gas, and the first heat exchanger exchanges heat between the low-temperature liquefied gas and the mixed gas cooled by the second heat exchanger, thereby making the cooled mixed gas the low-temperature gas.
[0008] Furthermore, it is preferable to control the supply amount of the low-temperature liquefied gas based on the temperature of the low-temperature gas. Moreover, it is preferable to control the supply amount of the gas based on the flow rate of the low-temperature gas. [Effects of the Invention]
[0009] According to the low-temperature gas generator of the present invention, the cold energy of the exhaust gas discharged from the object to be cooled can be effectively utilized to cool the mixed gas in the second heat exchanger, thereby reducing the amount of low-temperature liquefied gas required. Furthermore, by raising the temperature of the exhaust gas in the second heat exchanger, it is possible to prevent the generation of white smoke from the exhaust port and protect the exhaust piping. In addition, since no separate heat source or separate system is required, it is possible to reduce not only the cost of generating heat but also the installation space. [Brief explanation of the drawing]
[0010] [Figure 1] This is a schematic diagram showing one embodiment of the low-temperature gas generator of the present invention. [Figure 2] This is a diagram illustrating a conventional cryogenic gas generator. [Modes for carrying out the invention]
[0011] Below, an example of a low-temperature gas generator to which the present invention is applied will be described in detail with reference to Figure 1. Note that, for the sake of clarity, the drawings used in the following description may show enlarged versions of key features, and the dimensional ratios of each component may not be the same as those in reality.
[0012] The low-temperature gas generator 100 shown in Figure 1 is a device that generates a low-temperature gas to cool an object to be cooled 1 and exhausts the exhaust gas after the object to be cooled 1 has been cooled. The low-temperature gas generator 100 includes a low-temperature liquefied gas path L1 into which low-temperature liquefied gas A is introduced from one end, and a normal-temperature gas path L2 into which gas B, which is in a gaseous state at a temperature higher than the boiling point of low-temperature liquefied gas A, is introduced from the other end. It also includes a first heat exchanger 10 and a second heat exchanger 20.
[0013] As described later, through heat exchange, the low-temperature liquefied gas A in the low-temperature liquefied gas path L1 that has passed through the first heat exchanger 10 vaporizes to become vaporized gas C. The low-temperature liquefied gas path L1 and the ambient temperature gas path L2 merge, and gas B and vaporized gas C mix to form mixed gas D, which flows into the mixed gas path L3. The mixed gas D flowing through the mixed gas path L3 passes through the second heat exchanger 20 and the first heat exchanger 10, becoming low-temperature gas E which is introduced to the object to be cooled 1. The low-temperature gas E that has cooled the object to be cooled 1 is exhausted as exhaust gas F from the exhaust gas path L4.
[0014] Furthermore, the low-temperature gas generator 100 includes a flow control valve 30 provided in the low-temperature liquefied gas path L1, a mass flow controller (MFC) 40 provided in the ambient temperature gas path L2, a temperature sensor 50 and a flow meter 60 provided in the mixed gas path L3 downstream of the first heat exchanger 10, and indicator controllers 70 and 80.
[0015] The second heat exchanger 20 has a mixed gas path L3 and an exhaust gas path L4 running parallel inside, configured so that the mixed gas D and exhaust gas F flowing through each path exchange heat with each other. In particular, the mixed gas path L3 and the exhaust gas path L4 are arranged so that the mixed gas D and exhaust gas F flow in opposite directions, i.e., in a counterflow configuration. Through heat exchange in the second heat exchanger 20, the mixed gas D becomes even colder due to the coldness of the exhaust gas F, while the exhaust gas F is preferably heated to 0°C or higher, and at least -30°C or higher, before being exhausted. At around -30°C, even if white smoke is generated, it will not spread and will quickly disappear after mixing with the surrounding air and being heated, thus preventing the generation of white smoke. It is also possible to prevent condensation on the exhaust piping.
[0016] The first heat exchanger 10 has a low-temperature liquefied gas path L1 and a mixed gas path L3 running parallel inside it, and is configured so that the low-temperature liquefied gas A flowing through each path and the mixed gas D, which has been cooled by passing through the second heat exchanger 20, exchange heat with each other. In particular, the low-temperature liquefied gas path L1 and the mixed gas path L3 are arranged so that the low-temperature liquefied gas A and the mixed gas D flow in opposite directions, that is, they are counterflows. Through heat exchange in the first heat exchanger 10, the low-temperature liquefied gas A vaporizes into vaporized gas C, while the mixed gas D is cooled into low-temperature gas E which is introduced into the object to be cooled 1.
[0017] The flow control valve 30 controls the supply amount of the cryogenic liquefied gas A based on the difference between the temperature detected by the temperature sensor 50 and the target temperature of the indicating regulator 70. The cryogenic gas E in the mixed gas path L3 derived from the first heat exchanger is measured for its gas flow rate by the flow meter 60. Also, the mass flow controller (MFC) 40 controls the supply amount of the gas B based on the difference between the flow rate of the cryogenic gas E detected by the flow meter 60 and the target flow rate of the indicating regulator 80.
[0018] In this exemplary embodiment, liquid nitrogen is used as the cryogenic liquefied gas A, but other substances such as liquid oxygen, liquid argon, LNG, liquefied methane, liquefied hydrogen, and liquefied helium can also be used. Also, the gas B is a gas that is gaseous at a temperature higher than the boiling point of the cryogenic liquefied gas A, and nitrogen gas is used in this exemplary embodiment.
[0019] The flow meter 60 may use a Coriolis flow meter, vortex flow meter, electromagnetic flow meter, turbine flow meter, area type flow meter, etc. Also, although the mass flow controller (MFC) 40 is used for the flow control of the gas B, an automatic valve or the like may also be used. Also, the flow control valve 30 may also use other control means.
[0020] The object to be cooled 1 may be installed inside the device and directly cooled by the cryogenic gas E, or may be installed outside the device or cooled through another refrigerant cooling device.
Example
[0021] Using the cryogenic gas generator 100 of FIG. 1, liquid nitrogen with a pressure of 600 kPa (absolute pressure) and a saturated temperature is used as the cryogenic liquefied gas A, and nitrogen gas with a pressure of 600 kPa (absolute pressure) and 25 °C is used as the gas B to form a mixed gas D. To cool the object to be cooled 1, it is assumed that a cryogenic gas E with a flow rate of 100 kg / h and a temperature of -120 °C is generated, and this is taken as Example 1.
[0022] Further, a case where cryogenic liquefied gas A and gas B under the same conditions as in Example 1 are used with the conventional cryogenic gas generator 100A shown in FIG. 2 is set as a comparative example. In FIG. 2, components similar to those in FIG. 1 are denoted by the same reference numerals, and detailed descriptions thereof are omitted. The difference from FIG. 1 is the presence or absence of the second heat exchanger 20.
[0023] Table 1 shows the flow rates and temperatures of the respective gases at P1 to P8 in the drawings of the cryogenic gas generator 100 in FIG. 1 and the cryogenic gas generator 100A in FIG. 2.
[0024]
Table 1
[0025] In Example 1, in the second heat exchanger 20, the cold heat of the exhaust gas F is recovered to cool the mixed gas D, so less cryogenic liquefied gas A (liquid nitrogen) is required to generate the cryogenic gas E under the same conditions. Since liquid nitrogen requires more energy (electric power) for production than nitrogen gas and is expensive, it can be seen that the present invention is also advantageous in terms of cost.
[0026] Also, in the comparative example, as shown by the numerical value at P7, since it is discharged to the atmosphere while being at a low temperature, water vapor in the atmosphere condenses and white smoke is generated. On the other hand, in Example 1, as shown by the numerical value at P8, since it is heated to 0°C and discharged, no white smoke is generated.
[0027] According to the present invention, not only can the cold heat of the exhaust gas F discharged from the cooling object 1 within the same system be effectively utilized, but also by reheating the temperature of the exhaust gas F to at least -30°C, it is possible to prevent the generation of white smoke from the exhaust port and protect the exhaust pipe. Also, a separate heat source or a separate system is not required, and not only can the cost of generating heat be suppressed, but also the installation space can be reduced.
Explanation of Reference Numerals
[0028] 1...Object to be cooled, 10...First heat exchanger, 20...Second heat exchanger, 30...Flow control valve, 40...Mass flow controller (MFC), 50...Temperature sensor, 60...Flow meter, 70,80...Indicating controller, 100...Low-temperature gas generator, 100A...Low-temperature gas generator, A...Low-temperature liquefied gas, B...Gas, C...Vaporized gas, D...Mixed gas, E...Low-temperature gas, F...Exhaust gas L1: Low-temperature liquefied gas path, L2: Room temperature gas path, L3: Mixed gas path, L4: Exhaust gas path
Claims
1. In a low-temperature gas generator that generates a low-temperature gas to cool an object to be cooled and exhausts the exhaust gas after the object has been cooled, A first heat exchanger generates vaporized gas by vaporizing low-temperature liquefied gas through heat exchange, A second heat exchanger that raises the temperature of the exhaust gas by heat exchange, Equipped with, The second heat exchanger exchanges heat between a mixed gas, which is a gaseous gas at a temperature higher than the boiling point of the low-temperature liquefied gas, and the vaporized gas, and the exhaust gas, thereby cooling the mixed gas. The first heat exchanger exchanges heat between the low-temperature liquefied gas and the mixed gas cooled in the second heat exchanger, and the cooled mixed gas becomes the low-temperature gas. A low-temperature gas generator characterized by the following features.
2. The cryogenic gas generator according to claim 1, characterized in that the amount of supply of the cryogenic liquefied gas is controlled based on the temperature of the cryogenic gas.
3. The low-temperature gas generator according to claim 1 or 2, characterized in that the amount of gas supplied is controlled based on the flow rate of the low-temperature gas.