WO2019218997A1

WO2019218997A1 - Method and device for filling dry dewar tank

Info

Publication number: WO2019218997A1
Application number: PCT/CN2019/086791
Authority: WO
Inventors: 曾艳; 刘奔; 许慎启
Original assignee: 乔治洛德方法研究和开发液化空气有限公司
Priority date: 2018-05-15
Filing date: 2019-05-14
Publication date: 2019-11-21
Also published as: WO2019218143A1; CN112105862B; CN112105863B; CN112105863A; CN112105862A

Abstract

A method and device for filling a dry dewar tank. A low-temperature liquid is filled into a dry dewar tank that is provided with a porous adsorbent material capable of adsorbing the low-temperature liquid, and a vacuum state is reached inside of the dry dewar tank by means of vacuuming. The present method and device greatly increase the adsorption of a low-temperature liquid by a porous adsorbent material, may achieve rapid and efficient filling, obtain a high-quality cold source, and improve the effective cold preservation duration of the dry dewar tank.

Description

Method and device for filling dry dewar tank

Technical field

The present invention relates to a method and apparatus for filling a dry dewar tank, and more particularly to a method and apparatus for filling a dry dewar with a cryogenic liquid.

Background technique

Nitrogen is a special industrial product with a boiling point of -196 ° C at standard atmospheric pressure. Liquid nitrogen is widely used in the fields of precision instrument manufacturing, medicine and food. The ultra-low temperature properties of liquid nitrogen inhibit the metabolism of cells such as cells and embryos, allowing cells and embryos to be preserved for a long time. Therefore, liquid nitrogen is widely used in medicine and bioengineering, especially for vaccines, bacterial strains, cells and humans. Active storage of biological samples such as animal organs. At the same time, liquid nitrogen can also be used in precision instrument manufacturing, cryogenic processing of metal materials, cryogenic assembly of precision parts, and medical surgical refrigeration. For the freezing conditions of the cells, it has been confirmed by many experiments that the cells should be slowly lowered from room temperature to -80 ° C at a rate of 1-3 ° C per minute, so as to avoid the formation of large ice crystals in the cells and reduce damage to the cells. . When cells are stored for long periods of time, they must be stored in a liquid nitrogen container in order to maintain the ambient temperature below -135 ° C. When the cells are in this environment, the water molecules will enter the glass transition. Molecular activity within the cell, as well as biological activity, will completely stop and go to sleep. Figure 1 is a three-phase diagram of nitrogen with a triple point temperature of -210 ° C and a triple point pressure of 12.5 kPa.

The Dry Shipper is manufactured according to the vacuum jacket insulation principle invented by British scientist Dewar in 1898. It scientifically solves the problem of low temperature liquids such as liquid nitrogen, liquid argon, liquid oxygen, etc. during storage. The problem of large evaporation loss of cryogenic liquids caused by convection, conduction and radiation. With the development of science and technology and the advancement of human society, high-vacuum multi-layer insulation technology and its new materials and new processes have been adopted, so that Dewar can have excellent thermal insulation performance, and it can save the natural evaporation loss of cryogenic liquid. It has been reduced to a minimum. Therefore, dry Dewar products are widely used in animal husbandry, medical and scientific research, and mechanical processing.

The inner cavity of the dry dewar can be placed with a porous adsorbent material, which can efficiently adsorb the cryogenic liquid in the tank. After a small amount of cryogenic liquid in the space of the tank without adsorbing material evaporates, the low temperature liquid in the adsorbent slowly evaporates and maintains the inside of the container. Low temperature. The low temperature liquid in the dry Dewar tank is adsorbed and fixed by the porous adsorbent material, and liquid sloshing does not occur during transportation. Even if the tank body is dumped, liquid nitrogen will not flow out, and the liquid nitrogen evaporation in the tank will not be increased. This increases the working time of the dry dewar tank, ensuring the effective cryopreservation time in the tank and the safety of the refrigerated active biological materials and the use site. Therefore, the dry Dewar can be accepted by the airline as carry-on baggage and can be transported on the road by the courier company.

In addition, a solid-liquid mixture of nitrogen (also known as nitrogen slurry, Slush Nitrogen) refers to a liquid-solid two-phase cryogenic fluid formed by suspending small particles of solid nitrogen in liquid nitrogen, which is a high-quality cold source. Nitrogen pulp has a wide range of applications in biomedical and superconducting fields. Compared to liquid nitrogen, the cooling capacity of the same unit mass of nitrogen slurry is greater due to the use of latent heat of fusion of solid nitrogen (melting point of -209.98 ° C at standard atmospheric pressure).

In the prior art, the liquid nitrogen dewar tank is generally filled with liquid nitrogen by a differential pressure method, and the low temperature liquid nitrogen is controlled by the pressure difference to be charged from the higher pressure liquid nitrogen storage tank through the liquid phase pipeline tank to the lower pressure liquid nitrogen. In the Dewar, the pressure of the liquid nitrogen storage tank is about 0.6MPa or more, and the pressure of the Dewar tank is controlled below 0.4Mpa, so that the pressure difference between the two is kept at 0.2Mpa, and the liquid nitrogen will be continuously charged from the storage tank. Into the Dewar. Another common method of filling liquid nitrogen is to directly use a funnel casting method. This is especially important to make the end of the funnel slightly away from the neck of the dry Dewar, so that the vapor of liquid nitrogen can be evaporated from the funnel. The gap between the dry Dewar can escape smoothly, otherwise the liquid will overflow from the funnel, which will not only increase the loss of liquid nitrogen, but also cause frostbite accidents. Before filling the liquid nitrogen, a small amount of liquid nitrogen should be kept in the pre-cooled state. The speed of filling the liquid nitrogen should be slow. First, inject a small amount, then stop for a few minutes, then cool it and gradually fill it to the specified capacity. For dry dewar tanks, it is necessary to repeat the filling several times in order to adsorb sufficient liquid nitrogen to the adsorbent material. Generally, add liquid nitrogen to the bottom of the neck tube, keep the tank standing, wait for the liquid nitrogen to be adsorbed, add liquid nitrogen at intervals (for example, 10 minutes), repeat the process 5-15 times until the liquid nitrogen reaches the neck tube. When the bottom is no longer adsorbed, the filling is completed, and the excess liquid nitrogen in the tank must be poured out, and the filling amount of the liquid nitrogen is measured.

However, in the above-mentioned existing standard filling method, the use of a porous adsorbent material in a dry Dewar tank to adsorb a cryogenic liquid (such as liquid nitrogen) occurs about 15% to 40% (related to the type of adsorbent material). The pore free volume cannot be completely filled, possibly due to trapped residual air and incomplete wetting in the pores of the porous adsorbent material. Therefore, the adsorption of liquid nitrogen in the porous adsorbent material is slow, and it takes a long time (20 hours or even several days). When the porous adsorbent adsorbs the cryogenic liquid close to saturation, even if the filling is continued, the amount of the cryogenic liquid that can be adsorbed is extremely small. . Moreover, the quality of the cans is unstable, and the difference in the holding time of the canned cans under the same conditions is also large.

In summary, how to invent a method and apparatus for efficiently filling a dry dewar can be a technical problem to be solved by those skilled in the art.

Disclosure of invention

The main technical problem to be solved by the present invention is how to quickly and efficiently fill a dry dewar tank with a cryogenic liquid, reduce the loss of low temperature liquid raw materials, and provide a dry dewar tank with a lower working temperature and/or extended dry type. Effective working hours of Dewar cans. Accordingly, the present invention discloses a method and apparatus for filling a dry dewar tank, which is filled with a cryogenic liquid in a dry dewar tank provided with a porous adsorbent material capable of adsorbing a low temperature liquid, and is dried by vacuuming. The vacuum in the Dewar tank is liquefied to liquefy the nitrogen and oxygen in the air adsorbed in the porous adsorbent, so that the cryogenic liquid (such as liquid nitrogen) is filled into the volume originally occupied by the air, compared to the dry type filled directly with liquid nitrogen. In the dewar tank, the dry dewar tank of the present invention has a larger liquid nitrogen filling amount, so that the adsorption of the low-temperature liquid by the porous adsorbent material can be further increased, and the rapid and efficient filling can be realized, and a high-quality cold source can be obtained.

When liquid nitrogen is used as the cryogenic liquid for filling, the temperature of the liquid phase in the inner chamber of the dry Dewar tank is about -196 ° C, and the operating temperature of the gas phase is between -190 ° C and -170 ° C. As the liquid nitrogen adsorbed in the porous adsorbent volatilizes, the temperature in the dry Dewar tank gradually increases, and the present invention can provide a dry dewar tank with an initial working temperature lower than -170 ° C or even lower than -196 ° C, even It is a dry dewar tank with an initial working temperature of about -210 °C. It is better suited for cryopreservation of biological samples and is more suitable for long-distance transportation.

Still another technical problem to be solved by the present invention is to prepare a solid-liquid mixture of nitrogen simply and efficiently while efficiently filling liquid nitrogen into a dry dewar. The dry dewar tank with the porous adsorbent material capable of adsorbing the low-temperature liquid is filled with liquid nitrogen, and the dry dewar tank is brought into a vacuum state by vacuuming, and the temperature in the dry dewar tank at this time Maintaining a temperature close to the triple point of nitrogen to achieve rapid and efficient filling of liquid nitrogen in the porous material, the dry dewar tank cavity is continuously formed into solid nitrogen by the supercooled liquid nitrogen adsorbed by the porous material. The solid-liquid mixture of nitrogen can be taken out as a cold source for use.

In a first aspect of the invention, a method of filling a dry Dewar can be provided, comprising the steps of:

(a) providing a dry dewar tank comprising a porous adsorbent material for adsorbing a cryogenic liquid placed in the interior of the dry dewar;

(b) providing a vacuuming device for reducing the pressure of the cryogenic liquid in the dry Dewar tank, the vacuuming device comprising a vacuum pump;

(c) optionally pre-cooling the dry Dewar;

(d) continuously and/or intermittently charging the cryogenic liquid into the dry Dewar tank;

(e) when the adsorption of the porous adsorbent material at a standard atmospheric pressure reaches a state close to saturation, the vacuuming device is activated to bring the dry dewar tank into a vacuum state;

(f) optionally, repeating steps (d) to (e) to cause the porous adsorbent material to sufficiently adsorb the cryogenic liquid;

(g) optionally, after the vacuuming is stopped, the cryogenic liquid is continuously filled into the dry Dewar to sufficiently adsorb the porous adsorbent;

(h) selectively discharging a cryogenic liquid that is not adsorbed by the porous adsorbent material;

(i) Closing the dry Dewar.

In some alternative embodiments, the vacuuming device includes a vacuum pump and a sealing head and tubing for sealingly connecting the vacuum pump to the inner cavity of the dry Dewar, optionally including measuring dry dewar a temperature measuring device for cryogenic liquid temperature and/or an observation window for observing the interior of the dry Dewar, optionally comprising a stirrer placed in the interior of the dry Dewar tank, optionally including for measuring Pressure gauge for the pressure inside the earthen jar.

In some alternative embodiments, the near-saturated state means that the level of the cryogenic liquid within the dry Dewar has not decreased significantly in a short period of time. In some alternative embodiments, the liquid level does not decrease significantly after 5 minutes. In some alternative embodiments, the liquid level does not drop significantly after 20 minutes.

In some optional embodiments, the porous adsorbent material is selected from the group consisting of phenolic resin, aerogel, alumina ceramic porous adsorbent, zirconia ceramic porous adsorbent, titanium dioxide ceramic porous adsorbent, metal foam, rice straw Fiber, or a combination thereof.

In some alternative embodiments, the porous adsorbent material has a porosity of from 50% to 99%. Especially for some aerogels, the porosity is up to 99%.

In some alternative embodiments, the porous adsorbent material has a porosity of from 50% to 94%.

In some alternative embodiments, the cryogenic liquid includes, but is not limited to, liquid nitrogen.

In some optional embodiments, in the step (e), when the vacuuming device is activated to bring the dry dewar into a vacuum state, the temperature in the dry dewar tank is lowered below the standard atmospheric pressure of nitrogen. The boiling temperature below.

In some optional embodiments, in the step (e), when the vacuuming device is activated to bring the dry dewar into a vacuum state, the temperature in the dry dewar tank is lowered and stabilized in the vicinity of the nitrogen Phase point temperature.

In a second aspect of the invention, an apparatus for filling a dry Dewar can be disclosed, comprising:

(a) a dry dewar tank comprising a porous adsorbent material disposed in a lumen thereof, wherein the porous adsorbent material is used to adsorb a cryogenic liquid;

(b) a vacuuming device for reducing the pressure of the cryogenic liquid in the dry Dewar tank, the vacuuming device comprising a vacuum pump;

(c) optionally includes a conduit for discharging the non-adsorbed cryogenic liquid.

In some optional embodiments, the vacuuming device comprises a vacuum pump and a sealing head and a conduit for sealingly connecting the vacuum pump to the inner cavity of the dry Dewar, optionally including a dry dewar tank a temperature measuring device for the internal cryogenic liquid temperature and/or an observation window for observing the inner cavity of the dry Dewar, optionally further comprising a stirrer placed in the interior of the dry Dewar tank, optionally comprising A pressure gauge that measures the pressure inside the Dewar.

According to a third aspect of the present invention, a dry dewar filled with the method of the first aspect of the present invention, comprising a porous adsorbent material adsorbed with a cryogenic liquid placed in a lumen thereof, is trapped in said The residual air in the pores of the porous adsorbent material is in a liquefied state, and the adsorption of the low temperature liquid by the porous adsorbent material is saturated.

The beneficial effects of the invention are:

1. The method and apparatus for filling a dry dewar tank according to the present invention can fill more cryogenic liquid in a shorter time, accelerate the process of adsorbing the cryogenic liquid by the porous adsorbent material, and provide a dry type with a lower working temperature. Dewar cans and extend the effective working time of dry dewars.

2. The method for filling a dry dewar tank according to the present invention improves the absorption capacity of the porous adsorbent material in the dry dewar tank, and the amount of liquid nitrogen absorbed can be increased by 15%-40%wt compared with the conventional method.

3. The method of filling a dry dewar tank according to the present invention can provide a dry dewar tank with an initial working temperature lower than -196 ° C, which can be used for deep cryopreservation of biological samples, and is more suitable for long-distance transportation.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings in the present disclosure are intended to be illustrative of the invention, and are not intended to limit the invention. The drawings are generally schematic and are not drawn to scale for clarity. All figures share the same reference numerals with respect to the same or corresponding technical features.

Figure 1 is a three-phase diagram of nitrogen.

Figure 2 is a schematic view showing the structure of a dry dewar in

Embodiments

1 and 2 of the present invention.

Figure 3 is a schematic view showing the structure of an apparatus for filling a dry dewar in

Embodiments

1 and 2 of the present invention.

Fig. 4 is a flow chart showing the filling of a dry dewar according to the first embodiment of the present invention.

1-dry dewar, 2-porous adsorption material, 3-vacuum device, 4-can lid, 5-sealing head, 6-vacuum pump, 7-temperature measuring device, 8-agitator, 9-observation window, 11 - Pipeline for discharging un-adsorbed cryogenic liquid, 12-weighing system.

The best way to implement the invention

As used in the present invention, "dry dewar", "dry dewar", "Dry Shipper", "dewar" have the same meaning and can be used interchangeably, both referring to a dry refrigerated container or dry type. Transport container with porous sorbent material designed for safe transport of samples. Dry dewars used in the embodiments of the present invention are commercially available, and as an example, Haier YDH-3, YDH-6-80, YDH-8-80, YDH-10-125, YDH can be selected. -10-125-F, YDH-25-216-F aluminum alloy biological transport liquid nitrogen biological container.

As used in the present invention, cryopreservation (or cryopreservation) refers to a technique of storing organic substances such as living things, living tissues, or cells and other substances at a low temperature of -196 ° C or lower. In general, cryopreservation refers to the preservation of biological materials or substances at temperatures below -196 ° C (ie below 77 K). At this temperature, all biological activities will theoretically stop, including some biochemical activities that will kill cells.

As used herein, "pressure-reduced" refers to the connection of a dry dewar tank to a vacuuming device for vacuuming such that the pressure in the interior of the dry Dewar tank is continuously reduced until it is below the saturation pressure of the cryogenic liquid. .

As used herein, the "vacuum state", "state near vacuum" means that the internal pressure of the dry Dewar tank is lower than the standard atmospheric pressure (101.325 kPa, ie 1 atm) to allow for the inside of the dry Dewar tank. The temperature is lowered below the boiling temperature of the nitrogen at standard atmospheric pressure, and further, it can be lowered and stabilized at a triple point temperature close to nitrogen.

As used in the present invention, the porous adsorbent material is a material which is composed of mutually penetrated or closed pores and has a high specific surface area and a high porosity, and the pores therein may be through holes, blind holes and/or closed cells. It includes, but is not limited to, phenolic resin, aerogel, alumina ceramic porous adsorbent, zirconia ceramic porous adsorbent, titanium dioxide ceramic porous adsorbent, metal foam, glass fiber, polyimide, silica, etc. Adsorbent material. The porous adsorbent material in the dry Dewar can absorb the cryogenic liquid to eliminate the risk of cryogenic liquid spillage during transportation. The amount of cryogenic liquid that can be absorbed determines the cold capacity of the dry Dewar.

It is generally known to those skilled in the art that the rate of adsorption of the porous adsorbent material depends on various factors such as porosity and the like. A very uniform network structure is formed on the surface and/or the pores of the porous adsorbent material, and a gas (such as air) can be trapped or adsorbed inside the network structure, and more cryogenic liquid can be absorbed into the pore through the capillary effect. Inside the road. Even for the same porous adsorbent material, liquid nitrogen below the gas-liquid equilibrium temperature (-196 ° C) and above the triple point temperature will have its own supercooling capacity, which can liquefy the residual air in the porous adsorbent material, especially the air. Nitrogen in the air so that the air does not remain as a residual bubble in the porous adsorbent material, which can increase the filling amount of liquid nitrogen in the porous adsorbent. Those skilled in the art can select dry dewars and porous adsorbent materials of different specifications according to needs.

As used in the present invention, the "nearly saturated state" means that after the low temperature liquid is continuously filled into the dry dewar tank under standard atmospheric pressure, the liquid level of the low temperature liquid does not decrease significantly in a short time, or the buoyancy liquid level gauge shows There is no change in a certain period of time, indicating that the adsorption of the porous adsorbent material has reached a "near saturation state". The "short time" can be set to be equal to or longer than 5 minutes, or equal to or longer than 20 minutes.

As used herein, the adsorption of a cryoabsorbent material to a cryogenic liquid "saturated" means that the cryogenic liquid is sufficiently adsorbed by the porous adsorbent material. By way of example, the use of liquid nitrogen as the cryogenic liquid means that during the filling of liquid nitrogen, the free volume portion of the pores that are not completely filled in the porous adsorbent material is filled with liquid nitrogen. After the vacuuming device is activated, the residual air trapped in the pores of the porous adsorbent material (especially nitrogen in the air) is liquefied (the boiling point of oxygen is -183 ° C at standard atmospheric pressure, which has been liquefied by liquid nitrogen during the filling process). ), thereby accelerating the filling speed and filling degree of liquid nitrogen.

As used herein, cryogenic liquids used to fill Dewar cans include, but are not limited to, liquid nitrogen.

As used in the present invention, "continuous or intermittent" charging of a cryogenic liquid into a dry Dewar means that the operation of "filling in a cryogenic liquid" can be carried out without interruption, or, every two times. During the operation of the cryogenic liquid, the same or different time periods may be spaced, for example, may be 1-120 minutes apart, or 5-90 minutes apart, or spaced 10-60 minutes apart.

Raw materials and instruments

In the exemplary methods of the following Example 1 and Comparative Example 1, the dry Dewar tanks are all made of Haier YDH-3 aluminum alloy biological transport liquid nitrogen biological container, and the main parameters are as follows:

Liquid nitrogen capacity: 3.0 L, caliber 50 mm, total height 428 mm, outer diameter 224 mm, empty weight 3.5 kg, static evaporation 0.14 L / day.

The invention is described in further detail below with reference to the accompanying drawings, but the invention is not limited to the embodiments described below.

Figure 2 is a schematic view showing the structure of a dry Dewar 1 in Examples 1 and 2 and Comparative Examples 1 and 2, comprising a porous adsorbent 2 for adsorbing a cryogenic liquid (e.g., liquid nitrogen) placed in the inner chamber thereof. With a porosity of about 90%, the can lid 4 maintains the internal and external pressure balance of the dry Dewar 1.

Embodiments

1 and 2 of the present invention, the dry dewar tank 1 is provided with a porous adsorbent 2, and the vacuuming device 3 is used for the dry dewar. The inside of the can is brought to a vacuum to liquefy the residual air trapped in the pores of the porous adsorbent 2. The vacuuming device 3 comprises: a vacuum pump 6; a sealing head 5 for sealingly connecting the vacuum pump 6 to the inner cavity of the dry Dewar 1; a line 11 for discharging the unadsorbed cryogenic liquid; for observing the dry type An observation window 9 for the interior of the Dewar tank; a temperature measuring device 7 for measuring the temperature of the cryogenic liquid in the dry Dewar tank. Wherein, the sealing head 5 is sealed with the dry Dewar 1 and further comprises an agitator 8 placed in the interior of the dry Dewar for agitation, the agitator being driven by a motor placed outside the dry Dewar ( Not shown in the figure, and a pressure gauge for measuring the pressure in the chamber of the Dewar.

Example 1:

Fig. 4 is a schematic view showing the process of filling a dry dewar in the first embodiment of the present invention. The entire filling process is carried out on the weighing system 12, the specific steps are as follows:

A) 3L dry dewar tank 1 provided with a porous adsorbent material 2 for adsorbing a cryogenic liquid in the inner cavity is filled with liquid nitrogen to the top of the bottle neck to pre-cool the inner cavity of the dry dewar tank;

B) Filling the dry Dewar tank 1 with liquid nitrogen to the neck tube and placing it for 10 minutes, the liquid nitrogen level in the dry Dewar tank will drop significantly, and so on 4 times;

C) continue to fill the liquid nitrogen to the neck of the dry Dewar;

D) To observe that the liquid nitrogen level has not decreased significantly, use the sealing head 5 to close the dry Dewar tank 1, open the vacuum pump connected through the pipeline and the dry Dewar tank cavity, start vacuuming, and monitor the temperature measuring device. Readings to reflect the internal temperature of the dry Dewar tank, the liquid nitrogen temperature in the dry Dewar tank will soon drop to -206 ° C, monitor the pressure gauge measuring the internal cavity pressure of the dry Dewar 1 and find the dry Du The pressure of the inner cavity of the earthen jar is quickly reduced to about 50 kPa, and the vacuum is continued. After about 30 minutes, the pressure of the inner cavity of the dry dewar tank 1 is reduced to about 12.5 kPa;

E) close the vacuum pump and open the sealing head;

F) stirring is started, and the liquid nitrogen in the inner cavity of the dry Dewar 1 is intermittently stirred;

G) After filling the liquid nitrogen again to the bottleneck, let it stand for about two hours.

(H) The liquid nitrogen which is not adsorbed by the porous adsorbent 2 is discharged, and the dry Dewar 1 is closed.

As the vacuum is carried out, the pressure in the dry Dewar tank is continuously decreased until it is lower than the saturation pressure corresponding to the liquid nitrogen. The liquid nitrogen spontaneously boils, and the sensible heat of the nearby liquid nitrogen is continuously absorbed during the boiling process as vaporization. The required latent heat causes the liquid nitrogen temperature to continuously decrease, and part of the liquid nitrogen in the dry dewar tank is vaporized and pumped out.

Comparative example 1:

The operation was carried out as in the steps A)-C) in Example 1, except that after the step C), it was allowed to stand for 16 hours, the stirring was started, and the liquid nitrogen in the inner cavity of the dry Dewar 1 was intermittently stirred, and Liquid nitrogen which is not adsorbed by the porous adsorbent is discharged, and the dry Dewar 1 is closed.

The total filling time required for Example 1 and Comparative Example 1 and the total amount of liquid nitrogen absorbed by the porous adsorbent material are listed in Table 1 below.

Table 1

It can be seen that after running the vacuuming device, the internal temperature of the dry Dewar can be reduced to a temperature close to the triple point of nitrogen. Under the same conditions, the amount of liquid nitrogen absorbed by the dry Dewar can be increased (2024.7-1449). /1449 = 40% wt, mainly due to the liquefaction of residual air trapped in the pores of the porous adsorbent material, thereby increasing the absorption capacity of the dry dewar tank for liquid nitrogen. Moreover, the method of the above embodiment requires only about one-fifth of the time of the conventional filling process to shorten the tank filling time to about 3 hours.

Example 2:

In the present embodiment, a certain amount of phenolic resin is used as the porous adsorbent material to explain that the method of filling the Dewar of the present invention can effectively improve the filling efficiency.

A') a 6L dry dewar tank provided with a phenolic resin as a porous adsorbent material in the inner cavity is filled with a small amount of liquid nitrogen to cool the inner cavity of the dry dewar tank;

B') Fill the dry Dewar tank with liquid nitrogen to the Dewar neck, and let it stand for 10 minutes, the liquid nitrogen level will drop;

C') continue to add liquid nitrogen to the neck of the dry Dewar;

D') Close the dry Dewar with a sealing head, open the vacuum pump connected through the pipeline and the dry Dewar inner cavity, evacuate, monitor the reading of the temperature measuring device, and drop the liquid nitrogen temperature in the dry dewar tank. To and stabilize at -203 ° C;

E') close the vacuum pump and open the sealing head;

F') The liquid nitrogen which is not adsorbed by the phenol resin is discharged, and the dry dewar tank is closed to balance the pressure inside and outside.

Comparative example 2:

The operation was carried out as in the step A')-C') in Example 2, except that the step C') was allowed to stand for 16 hours, the stirring was started, and the liquid in the inner cavity of the dry Dewar 1 was intermittently stirred. The dry dewar tank 1 is closed by nitrogen and discharging liquid nitrogen which is not adsorbed by the porous adsorbent.

Table 2 shows the total amount of liquid nitrogen absorbed by the porous adsorbent in the methods of Example 2 and Comparative Example 2, respectively, when a phenol resin was used as the porous adsorbent.

Table 2

It can be seen that, compared with the gas-liquid equilibrium condition (-196 ° C), after operating the vacuuming device, the internal temperature of the dry Dewar can gradually drop to a temperature close to the triple point of liquid nitrogen, and the unit weight of phenolic resin to liquid nitrogen The amount of adsorption increased by about (40-35) / 35 = 14 wt%.

In summary, the method and apparatus for filling a dry dewar tank of the present invention can fill more cryogenic liquid in a shorter time, and can increase the amount of cryogenic liquid absorbed by the dry dewar can by about 10% to 39. %wt, which greatly speeds up the process of adsorbing cryogenic liquids by porous adsorbent materials, and provides a dry dewar tank with lower working temperature. The effective working time of the dry dewar can be effectively extended in the case of the natural nature of the stored sample, the surrounding environmental conditions, the use of the tank and the measurement error.

Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the foregoing description should not be construed as limiting. Various modifications and alterations of the present invention will be apparent to those skilled in the art. Therefore, the scope of the invention should be defined by the appended claims.

Claims

A method of filling a dry dewar, comprising the steps of:

(a) providing a dry dewar tank comprising a porous adsorbent material for adsorbing a cryogenic liquid placed in the interior of the dry dewar;

(b) providing a vacuuming device for reducing the pressure of the cryogenic liquid in the dry Dewar tank, the vacuuming device comprising a vacuum pump;

(c) optionally pre-cooling the dry Dewar;

(d) continuously and/or intermittently charging the cryogenic liquid into the dry Dewar tank;

(e) when the adsorption of the porous adsorbent material at a standard atmospheric pressure reaches a state close to saturation, the vacuuming device is activated to bring the dry dewar tank into a vacuum state;

(f) optionally, repeating steps (d) to (e) to cause the porous adsorbent material to sufficiently adsorb the cryogenic liquid;

(g) optionally, after the vacuuming is stopped, the cryogenic liquid is continuously filled into the dry Dewar to sufficiently adsorb the porous adsorbent;

(h) selectively discharging a cryogenic liquid that is not adsorbed by the porous adsorbent material;

(i) Closing the dry Dewar.
The method of claim 1 wherein said vacuuming means further comprises temperature measuring means for measuring the temperature of the cryogenic liquid in the dry Dewar and/or for observing the interior of the dry Dewar tank window.
The method of claim 1 wherein said vacuuming means further comprises a sealing head and a conduit for sealingly connecting the vacuum pump to the interior of the dry Dewar.
The method of claim 1 wherein said near-saturated state means that the level of the cryogenic liquid in said dry Dewar has not decreased significantly over a short period of time.
The method of claim 1 wherein said near saturated state means that the level of the cryogenic liquid in said dry Dewar does not decrease significantly after 5-20 minutes.
The method according to claim 1, wherein said porous adsorbent material is selected from the group consisting of phenolic resin, aerogel, alumina ceramic porous adsorbent, zirconia ceramic porous adsorbent, titanium dioxide ceramic porous adsorbent, Foam metal, rice straw fiber, or a combination thereof.
The method of claim 1 wherein said porous adsorbent material has a porosity of from 50% to 99%.
The method of claim 1 wherein said cryogenic liquid is liquid nitrogen.
The method according to claim 8, wherein in the step (e), when the vacuuming device is activated to bring the dry dewar tank into a vacuum state, the temperature in the dry dewar tank is lowered to a low level. The boiling temperature of nitrogen at standard atmospheric pressure.
The method according to claim 8, wherein in the step (e), when the vacuuming device is activated to bring the dry dewar tank into a vacuum state, the temperature in the dry dewar tank is lowered and stabilized. At a triple point temperature close to nitrogen.
A device for filling a dry dewar tank, comprising:

(a) a dry dewar tank comprising a porous adsorbent material disposed in a lumen thereof, wherein the porous adsorbent material is used to adsorb a cryogenic liquid;

(b) a vacuuming device for reducing the pressure of the cryogenic liquid in the dry Dewar tank, the vacuuming device comprising a vacuum pump;

(c) optionally includes a conduit for discharging the non-adsorbed cryogenic liquid.
The device of claim 11 wherein said vacuuming means further comprises a sealing head and a conduit for sealingly connecting the vacuum pump to the interior of the dry Dewar.
The apparatus according to claim 11, wherein said vacuuming means further comprises temperature measuring means for measuring the temperature of the cryogenic liquid in the dry Dewar and/or observation window for observing the inner cavity of the dry Dewar tank .
A dry dewar filled with the method of claim 1 comprising a porous adsorbent material having a cryogenic liquid adsorbed in its interior, characterized by being trapped within the pores of said porous adsorbent material The residual air is in a liquefied state, and the adsorption of the cryogenic liquid by the porous adsorbent material is saturated.