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What is the name of the nitrogen tank? Dewar vessels: application and design features

HVM, an Italian company headquartered in Livorno, has been developing and manufacturing a wide range of cryogenic Dewars with different working pressures for more than 20 years, different systems removal of gases and liquids, vertical and horizontal, palletized control, etc. The company's products are used in the storage and transportation of gases at low temperatures. Areas of use:

industrial
scientific
food
fish farming
cryobiology
animal husbandry
pest control

Also, the company has developed installations for oxygen therapy (stationary “OXY-BLU” and compact “OXY-LIGHT”).

All products meet the European requirements ADR and TPED (Directive 2010/35/UE). Westmedgroup is the official supplier of cryogenic vessels for Russian market medical technology.

Dewar vessel - a vessel designed for long-term storage of substances at elevated or low temperatures. A constant temperature is maintained by passive methods, through good thermal insulation and/or processes in the stored substance (eg boiling). This is the main difference between the Dewar vessel and thermostats and cryostats.

The first container for storing liquefied gases was developed in 1881 by the German physicist A.F. Weinhold. It was a double-walled glass box with air evacuated from the space between the walls and was used by physicists K. Olszewski and S. Vrublevsky to store liquid oxygen.

The Scottish physicist Sir James Dewar improved the Weinhold glass box in 1892, turning it into a narrow-necked double-walled flask to reduce liquid evaporation. The space between the walls is silver-plated and the air is pumped out of it. Dewar hung this entire fragile structure on springs in a metal casing. Thanks to his development, Dewar was the first to obtain and preserve liquid (1898) and even solid (1899) hydrogen.

The first Dewars for commercial use were produced in 1904, when the German thermos firm Thermos GmbH was founded. In laboratories and industry, the Dewar vessel is used to store cryofluids, most commonly liquid nitrogen.

In medicine and veterinary medicine, special Dewar vessels are used for long-term storage of biological materials at low temperatures.

In geophysics, electronic components and crystals are placed in Dewar vessels when working in hot wells (from 400K).

Cryostats vary

by the type of refrigerant used (nitrogen, helium, hydrogen, etc.);

according to the material from which they are made (glass, metal, plastic);

according to its intended purpose (for radio engineering, optical, medical, and other research, for superconducting magnets, radiation receivers, etc.).

The advantage of using cryogenic vertical tanks is space saving compared to horizontal cryogenic tanks. However, vertical tanks require the development of a project for their installation and registration with the Rostekhnadzor authorities, unlike transport cryogenic tanks.

Cryogenic technology is special equipment, which allows to produce, store and transport various gases for a long time. At the same time, one of the main components of this equipment is the Dewar vessel.

What it is?

This item is a vessel of a special type, necessary for the storage of various substances, the temperature of which differs from the temperature of the redeeming medium (lower or higher). It is with the help of such vessels that it is possible to store substances with the desired temperature indicators for a long time. In general, the Dewar vessel acts like a familiar household thermos.

Dewar vessel structure

To ensure low thermal conductivity, the Dewar vessel is manufactured using a special technology. It consists of 2 tanks:

external;
internal.

Both of these containers are made of heat-resistant aluminum, however, in some cases, stainless steel can be used as the main material. Jumpers are provided between the tanks. They must be both thin and strong enough. Such characteristics can be provided by stainless steel, but recently it has been increasingly replaced by specialized durable plastic. There are other features that allow you to increase the effect of using the Dewar vessel.

The outer tank is covered with an absorbent. This additional protection allows you to effectively absorb gases that are released by the substance from the inside of the vessels.

A layer of thermal insulation on the outer vessel allows you to reduce thermal conductivity to a minimum.

The inner vessel also undergoes special preparation - it is carefully polished to give it perfect smoothness. A foam cylinder is installed on the lid, preventing the start of the convection process.

Dewar tanks

The development of Dewar vessels significantly influenced the storage and transportation of various substances, among which, liquid nitrogen. To store and transport substances in large volumes allow large containers, which are called "tanks". They can have a different volume, reaching 50 liters. Depending on the purpose of the application, you can choose from a very small or a large tank.

A distinctive feature of this vessel are the most durable walls, the presence of handles for easy carrying. Transportation of tanks with the help of handles is the most convenient and safe, even taking into account the low temperatures of the transported substance - cold burns do not threaten hands.

Applications for Dewar Vessels

Tanks, which allow storing and transporting substances with low temperatures, are widely used. This is especially true for the transportation and storage of liquid nitrogen in them. So, you can buy a Dewar vessel for completely different applications.

Medicine. Liquid nitrogen has found application in neurosurgery, gynecology, otorhinolaryngology, neurosurgery, surgery and other areas. With its help, malignant and benign tumors and various pathological tissues are removed. At the same time, the procedure is quick and painless, and after it there are no scars.
Cosmetology. In this direction, nitrogen has received no less popularity. With its help, it is possible to get rid of papillomas and warts. Cryomassage is carried out with nitrogen, as a result of which the skin acquires a healthy color, smoothness and youth. Cryosaunas are another place where you simply cannot do without a Dewar vessel. In just 2-3 minutes of being in a booth with liquid nitrogen, a person can begin to effectively lose weight, rejuvenate, and improve the condition of their skin.
Veterinary. Dewar tanks in this area can serve as a container for transporting biomaterials (used for artificial insemination of animals).
Laboratories. Liquid nitrogen is used in scientific companies and laboratories. In addition, such a container is necessary to keep many substances at a certain temperature.
Mechanical engineering and industry. Quite often, nitrogen is used to achieve increased strength of metal parts.
Cooking. Molecular cuisine... For these culinary delights based on the physico-chemical process, you also have to buy Dewars. It is with the participation of liquid nitrogen that chemical reactions occur. Restaurants working in the traditional direction of cooking, nitrogen is also useful. It helps to cool food instantly.
Entertainment. Dewar tanks are something without which many entertainment shows for children and adults are impossible.

Considering all of the above, we can conclude: Such cryogenic equipment as a Dewar vessel is widely used in many industries and sciences. Moreover, the demand for it is steadily growing.

Fragment of a patent application

Physicists Karol Olszewski and Zygmunt Wroblewski used a glass box with double walls to store liquefied gases, with air evacuated from the space between the walls. This container was developed by the German physicist Adolf Ferdinand Weinhold.

Device

The original Dewar flask was a glass flask with double walls, between which the air was pumped out. To reduce the radiation loss, both inner surfaces of the bulb were coated with a reflective layer. Dewar used silver as a reflective coating. A similar design is also used in modern cheap household thermoses.

Modern designs

Modern Dewar vessels are constructed somewhat differently. The inner and outer vessels are made of aluminum or stainless steel. The thermal conductivity of the material is not important, but strength and weight play a big role. The neck connects the inner and outer vessels. In dewars with a volume of up to 50 liters, the inner vessel is attached only to the neck and it experiences great physical stress. It also has high requirements for thermal conductivity. Those. the neck should be strong, but thin. In ordinary vessels, the neck is made of stainless steel. In high-quality Dewar flasks, the neck is made of durable reinforced plastic. This raises the problem of vacuum-tight fastening of metal and plastic. Outside, the inner vessel is covered with an adsorbent, which, when cooled, absorbs residual gases from the vacuum cavity. To reduce heat loss, the inner vessel is covered with additional thermal insulation. To reduce convection heat transfer, a foam cylinder is attached to the Dewar lid, which does not tightly close the neck. The vacuum cavity is pumped out to a pressure of 10 -2 Pa. Silvering of internal surfaces was abandoned and replaced with polishing.

Modern Dewar vessels have low evaporation losses: from 1.5% per day for large containers, up to 5% per day for small volumes.

Helium Dewars

Diagram of a Dewar vessel for helium
1 - neck for filling nitrogen;
2 - head with fittings;
3 - neck of the helium container;
4 - container for liquid nitrogen;
5 - thermal screens;
6 - container for liquid helium;
7 - thermal insulation;
8 - adsorbent

Links

Specifications, nitrogen storage in a Dewar

Wikimedia Foundation. 2010 .

See what "Dewar vessels" are in other dictionaries:

- (by the name of J. Dewar) vessels with double walls, between which a vacuum is created [not less than 1.33 mN/m2 (10 5 mm Hg)], which provides high thermal insulation of the substance inside the vessel. Heat transfer in D. with. almost happens...

Dewar vessel- Dewar vessels: a, b glass; into metal for liquid gases (nitrogen and helium). DEWAR VESSEL, a flask with double walls silvered on the inside, from the space between which air is pumped out. Thermal conductivity of a rarefied gas between the walls ... ... Illustrated Encyclopedic Dictionary

A flask with double walls silvered on the inside, from the space between which the air is pumped out. The thermal conductivity of the rarefied gas between the walls is so small that the temperature of the substances placed in the Dewar vessel remains constant for a long time ... encyclopedic Dictionary

Vessel with double walls, between which a vacuum of at least 1.33 mN/m² (10–5 mm Hg) is created, which provides high thermal insulation of the internal volume of the vessel. Proposed by the English physicist J. Dewar in 1898. The simplest Dewar vessel ... ... Encyclopedia of technology

- [in the name of the English. physicist and chemist J. Dewar (J. Dewar; 1842 1923)] a vessel with double walls, a vacuum is created between them, which provides high thermal insulation in the vessel inside the vessel. Small D. with. made of glass, vessels ... ... Big encyclopedic polytechnic dictionary

For liquid oxygen A Dewar vessel is a vessel intended for long-term storage of substances at high or low temperatures. Before being placed in the Dewar vessel, the substance must be heated or cooled. Constant temperature ... ... Wikipedia

VESSEL DEWAR- A special refrigerating vessel for freezing and storing sperm of producers in liquid nitrogen. It is a double-walled container made of aluminum alloys or stainless steel. A special thermal insulation is placed between the walls. For increase … Terms and definitions used in breeding, genetics and reproduction of farm animals

- (from Cryo... and Greek states standing, motionless) A thermostat in which the working unit or the object under study is maintained at temperatures below 120 K (cryogenic temperatures) due to an external source of cold. Usually as... Great Soviet Encyclopedia

Cryogenic temperatures, usually temperatures below the boiling point of liquid air (about 80 K). Such temperatures are usually counted from absolute zero (See Absolute Zero) temperature (273.15 ° C, or 0 K) and expressed in kelvins ... ... Great Soviet Encyclopedia

The thermos was invented by the efforts of three people over a quarter of a century. In 1879, physicist Professor A. Weinold suggested using a double-walled glass vessel with a vacuum between the walls to store liquid gases. In 1890, the English chemist Professor James Dewar improved the Weinhold bottle by silvering the walls, which reduced heat leakage through the walls. Finally, in 1904, the Berlin glassblower R. Burger added a protective shell to the Dewar vessel and began to sell it as a thermos for hot coffee or broth.

The Dewar vessel is a “vessel in a vessel” reservoir, the interwall space of which is filled with multilayer insulation (aluminum foil ADI-M-0.011 and glass paper - EVTI-7 glass veil) and air is evacuated during manufacture to a residual pressure of 10 (-4) mm Hg. To maintain a deep vacuum, an adsorbent and a hydrogen absorber are located in the interwall space. The material of the vessel is AMts aluminum alloy, thanks to which the temperature in the upper zone of the Dewar vessel does not rise above minus 170 degrees Celsius even if it contains 5 kg. (12%) liquid nitrogen.

Currently, cryogenic equipment is commercially produced ( Greek cryos- cold, genos- birth) of different types and brands: industrial Dewar vessels - SDP: SDP-5, SDP-10, SDP-16, SDP-25, SDP-40, etc. (the figure means the capacity of the vessel in liters); SD - agricultural: SDS-5, SDS-20, SDS-30, Kh-30 (Kharkov-30), etc.; stationary storage facilities - KhSZhA, KV-6202, KhB-0.5 (for 500 liters), KhB-0.2 (for 240 liters), etc.

The most important characteristic of the Dewar vessel is the period of complete evaporation of liquid nitrogen, which for all SDP and SDS is 30-35 days, and in the old type AT-6 vessels - up to 20 days. Evaporation of liquid nitrogen from SDP-5 to SDP-40 is from 10 to 24 g/h (4.8-1.8% per day!), in SDS-20, SDS-35, SDS-50 respectively 10.12.14 g/h.

Dewar vessels of the new generation "SDS-35M" and SDS-6M - have a more perfect multi-layer thermal insulation and high vacuum; inner and outer layers of aluminum alloy connected by a fiberglass neck, while the time of complete evaporation of liquid nitrogen reaches 300 and 48 days, respectively, and the evaporation of liquid nitrogen is 3.9 and 4.6 g/hour. (See Fig. Diagram of the Dewar vessel).

Liquid nitrogen is a colorless liquid appearance resembles water. Its boiling point is -196 °C, specific gravity 0.804 kg/l, heat of evaporation -47.7 kcal/kg. Of all cryogenic liquids obtained by liquefying atmospheric air (liquid air, liquid oxygen -183 ° C), liquid nitrogen is the least dangerous, chemically inert. Evaporating, it turns into gaseous nitrogen, which is colorless, odorless, non-flammable, its specific gravity is 1.16 kg/m3, molecular weight is 28; in atmospheric air, it is contained in an amount of 79%. With prolonged inhalation of air with a high nitrogen content (a decrease in the oxygen content of less than 16%), a person experiences a headache, and with high concentrations of nitrogen (for example, pouring nitrogen out of a fallen Dewar vessel) - fainting. Therefore, in rooms where they work with liquid nitrogen, there must be forced ventilation. At the checkpoint, Dewar flasks are stored in an arena, in a place or laboratory specially fenced off with a grate, at such a distance from a window or door that a hose for filling with liquid nitrogen can reach it.

In case of falling, impacts, sharp shocks, the connection of the inner and outer vessels may be broken, since they are connected only in the neck area, which is accompanied by a loss of vacuum, therefore, during transportation, it is necessary to securely fasten the Dewar vessel in the back of cars. The first sign of loss of vacuum is icing, the appearance of frost - the formation of a "snow coat" in the area of the neck of the casing of the Dewar Vessel, while the liquid evaporates very quickly. It is strictly forbidden to leave such Dewar vessels for heating in a room where people can be, since an increase in pressure in the interwall space can lead to an explosion. Dewar vessels that have lost vacuum are heated for at least three days in an isolated room, and then sent for repair to the manufacturer.

Features of the operation of Dewar Vessels is that the operator must regularly determine the level of liquid nitrogen in them. The first measurement is made a week after topping up, the second - a week after the first. The measurement results are recorded in the journal. For conventional Dewars, a third measurement should be taken within the third week after topping up, while recording the ambient air temperature and the number of times the Dewar was opened. You can determine the level of liquid nitrogen with a special metal probe - a measuring ruler: it is lowered into the Dewar vessel to the bottom and held for 15-20 seconds, removed - the frozen zone will show the amount of nitrogen in the Dewar vessel.

For their needs, not everyone has an idea about their device. Now we will tell you how this container is arranged and why, being in it, cryogenic liquids retain their properties.

The prototype of a modern vessel

The first storage tank for cryogenic liquids was invented at the end of the nineteenth century in Germany. Then it was a glass box with double walls, between which a vacuum was created. The Scottish scientist J. Dewar improved the invention by giving it the shape of a flask with a narrow neck.

This design was not chosen by chance - a narrow neck prevents the rapid evaporation of cryogenic liquids, and the vacuum in the interwall space helps maintain the desired temperature of the substances. The walls from the inside were subjected to silvering, which provided additional thermal insulation. With the advent of new technologies, the design was improved until we got the product that we use now.

Design of modern Dewar vessels

Modern products that we are used to are somewhat different from their predecessors. While the first Dewars were made of glass, they are now made of aluminum or stainless steel. An important role in the choice of material is played by strength and weight.

The main components of the Dewar vessel:

external and internal vessel;
neck;
lid;
adsorbent for the interwall space.

The outer and inner vessels are connected at the neck. From the space between them, air is pumped out to a pressure of 10 −2 Pa (a vacuum is created). The walls of the inner vessel are covered with an adsorbent from the outside. This was done to remove residual gases from the vacuum space.

The neck connects both parts of the vessel. Depending on the model, the neck can be narrow or wide enough (up to 210 mm in diameter). It is made of reinforced plastic, stainless steel can be used to reduce the cost of production.

The lid of the vessel allows you to tightly (but not hermetically) close the neck. A foam cylinder is additionally attached to it, which closes it and helps to bleed excess liquid nitrogen. They abandoned the silvering of the walls of the vessel, replacing it with polishing.

If you are looking for Dewars with high technical specifications, we recommend ordering them in our store. All products are accompanied by a guarantee, and a large selection of products will allow you to choose the best option.