What are the main areas of application of liquid nitrogen?
Editor:adminClick：
Time:2017-09-29 10:00
Liquid nitrogen: liquid nitrogen. Is inert, colorless, odorless, non-corrosive, nonflammable, very low temperature. Nitrogen constitutes the majority of the atmosphere (volume ratio of 78.03%, weight ratio of 75.5%). Nitrogen is inactive and does not support burning. A large number of endothermic contacts during vaporization cause frostbite.
Liquid nitrogen is a more convenient cold source, because of the nature of liquid nitrogen, has gradually been people's attention and recognition, in animal husbandry, medical care, food industry, and low temperature research and other fields have been more and more common application. In the electronics, metallurgy, aerospace, machinery manufacturing and other applications continue to broaden and develop.
First, the application of liquid nitrogen in animal husbandry
1, widely used in six animal frozen with improved skills in a variety of six animals, cattle semen frozen preparation, survival skills, since the last century 50 years has formed a complete set of process.
Bovine semen frozen cold source widely used liquid nitrogen. Granules of semen in the liquid nitrogen cooled by the fluorine plate (PTFE), copper gauze, aluminum on the frozen. To allow the surface of the semen to receive liquid nitrogen surface - set the interval (1 ~ 2 cm). In the course of freezing, to maintain the temperature at -80 ~ -120 ℃. Before the freeze will be balanced after the semen enrichment, and check the sperm viability. Drops to be agile, the particles should be symmetrical, diluted by 10 cents per milliliter of fine drops is appropriate After the end of the freeze, to pause 2 to 3 minutes until all the particles have been frozen immediately put into liquid nitrogen. Sampling check (the same is usually randomly selected 2), thawed viability of 0.3 or more, you can install in the gauze bag, after the mark in the liquid nitrogen to survive. After each drop of frozen bulls of a semen, you must swap the fluoride plate and other appliances. Now, the capacity of the tube is 0.25 ml and 0.5 ml, made of non-toxic plastic (polyvinyl chloride). The end of the tube filled with tampons and polyethylene powder, the powder is cured by water that is active sealing, and when the semen is pushed into the semen of the piston; the other end of the injection of semen, polyethylene or steel (or plastic beads) To be careful in the seal and the semen between 10 to 13 mm away from the space, to prevent the freezing process caused by expansion caused by thin tube burst.
Semen storage of frozen semen of liquid so liquid nitrogen to do cold storage, if necessary, can be removed at any time. In order to prepare for the impact of temperature changes on the quality of semen, take action to be agile, even if the elimination of the time in the atmosphere pause. When the frozen semen is extracted from the storage container, the semen should not override the neck of the liquid nitrogen container and stop the landing of the semen thawing rate due to the temperature rise. Cow frozen semen has been more than 40 years of history. Test proved that the survival of the frozen semen still has the ability to inseminate. But the same is usually thought that the frozen semen of cattle with the extension of survival time, sperm vigor and insemination skills gradually low. Cow frozen semen long-term survival is simply cut the time limit, still need to inherit research and inspection.
2, six animals and a variety of animals in the embryo transfer, the preparation of survival embryos
Now more to accept the embryo freezing device, is an intelligent freezer. The instrument to accept the computer control skills, special software, can more accurately control the amount of liquid nitrogen emissions, so as to ensure that the frozen biological products to the appropriate freezing rate cooling frozen.
3, liquid nitrogen ultra-low temperature collection of microbial skills
The method of collection of bacteria at -196 ℃ liquid nitrogen permanent collection method, its principle is the use of microorganisms in the following -130 ℃ metabolism tends to stop and useful collection of microorganisms. Large fungi are an important group in the fungi (a kind of fungi that form large fruiting bodies in the bacteria, which refers to the mushrooms or mushrooms in the broad sense). Many species have high nutritional and medicinal costs. There are some large-scale fungi can probably analyze the dead plants, to maintain the natural material circulation, ecological balance has an important role, can be opened up for the paper industry and environmental purification; some large-scale Fungi can cause tree disease or against a variety of wood products, the understanding of such pathogenic fungi to strengthen, is conducive to prevention and elimination of the occurrence of harm. Examples of large-scale fungi collection to deal with microbial strains of resources, quiet and efficient collection, and for the long-term useful collection of genetic resources, remote collection of biodiversity sharing has great significance
4, the survival of agricultural biological genes
Shanghai invested more than 4100 million yuan to set up equipment to deploy China's first integrated agricultural bio-gene database. Agriculture industry, said the most promising market development potential of the seed industry, this gene pool will be used as breeding material source. The total construction area of 3300 square meters of Shanghai agricultural biology gene bank, located in the Shanghai Academy of Agricultural Sciences, will be planted seeds, plant in vitro material, animal germ cells, microbial strains and plant genetic engineering materials five categories of agricultural biological genetic resources.
5, the survival of liquid nitrogen vaccine
Liquid nitrogen seedling is the middle and mid-80 years to promote the use of the first, the first use of type Ⅲ-FCl26 chicken chicken herpes virus liquid nitrogen seedlings, and then the sea surface and developed SBl, 301 / B, Z4, 814 and other liquid nitrogen vaccine, And combined into II + III type divalent seedlings and I + II + III trivalent seedlings, after the application were once useful to control some areas of chicken Marek's disease, II + III type divalent seed did not last long, 1993 Marek's disease in North America and the severe areas of the emergence of a wide range of prevalence, for the control of Marek's disease, some countries began to learn the Netherlands since 1927, the use of type I CV1988 / Rispens liquid nitrogen seedlings, the useful control of Marek's disease In the United States, Canada, Brazil, Japan, and Europe, CV1988 / Rispens has been introduced from the Dutch Ministry of Agriculture and Fisheries to produce and seeded in liquid nitrogen tanks in different countries.
6, with liquid nitrogen treatment of dairy cow milk nipple outside the mouth closed, six animal skin tumors are also more ordinary.
Second, liquid nitrogen in medical miracle applications
1, low temperature medicine
China's clinical low-temperature medical things grow agile, promote the growth of transplant medicine, exceptionally in bone marrow, hematopoietic stem cells, skin, cornea, excretion of glands, and blood vessels and valves and other frozen survival and transplantation applications have achieved significant results. Successful hematopoietic stem cell transplantation relies on the survival of hematopoietic stem cells. Biological samples in the cooling process, when the liquid from the solid to the phase change phase of the phase will release the heat, so that the temperature rise, do not control the cooling rate of the freezing process will lead to structural cells died. The phase change point of the biological sample is measured correctly, and the temperature of the microcomputer is reduced in order to increase the input amount of the liquid nitrogen when the sample is changed, and the temperature of the phase change sample is increased, and the cell is quietly and aggravably transversed Is the key to improving the survival rate of frozen samples.
2, clinical medicine
Liquid nitrogen is now the most widely used refrigerant in cryosurgery. Is invented by now the best of a refrigerant, put it into the low temperature medical device, like a scalpel, you can do any surgery. Frozen is a treatment with low temperature to crush the lesion. Cells due to the rapid changes in temperature, the structure of the crystal form, so that cells dehydration, shrinkage, resulting in changes in electrolytes, etc., can also make the local blood flow rate slow, microvascular blood stasis or embolism caused by cell hypoxia death.
It was reported that liquid nitrogen was frozen in the treatment of 2138 cases of facial hyperplasia and chromogenic diseases, of which 1 445 cases were cured, the cure rate was 67.59%; 329 cases markedly effective, 207 cases of total use rate of 82.97%. The cure rates of spots and seborrheic keratosis were 79.23% and 84.69% respectively. 52.25% of the nevus (including sunspots) and 41.67% of the eyelid tumor. Flat warts after freezing a new rash in the skin lesions issued, so to deal with the time of the flat warts should not be admitted to cryotherapy, quiescent frozen results. 2 cases of patients with chloasma after the mole treatment of pigment calm, the 2 cases after the useful treatment of pigment recovery normal, suggesting that those who have chloasma also should not accept the frozen treatment. The treatment of the nevus, according to the site and the patient's request to accept the appropriate treatment, sunspots and smaller stains (diameter <3mm) can be treated by liquid nitrogen freezing method, the larger mole should be surgical resection parallel Pathological examination is better.
It is one of the methods of treating aseptic warts in the treatment of sharp condyloma, non-toxic side effects, low pain, high cure rate, low recurrence rate, no scars after operation, less complication, short treatment time and economy Treatment of chronic pharyngitis by liquid nitrogen cryotherapy in the treatment of chronic pharyngitis, direct injection of liquid nitrogen on the surface of the disease, cooling fast, deep, wide, wide, And can clear the central area, received proud of the recent results. Each freeze-thaw cycle in about 1min, a row of 4 to 5 freeze-thaw cycle. Only once a week.
Third, liquid nitrogen in the food industry applications
1, liquid nitrogen in food quick-frozen application
In the vast collection of law, the most widely used frozen collection method, the results are also very obvious. And as one of the frozen collection method liquid nitrogen quick-frozen has long been accepted by food processing enterprises, because it can achieve low temperature cryogenic ultra-fast freezing, but also conducive to the realization of frozen glass part of the food, so that food can be thawed to maximize recovery To the original strange state and the original nutritional status, a very fierce progress in the frozen food character, so in the frozen industry to show the unique vitality. Compared with other freezing methods, liquid nitrogen quick freezing has the following obvious advantages:
① freezing rate is fast (freezing rate is usually about 30-40 times faster than the usual freezing method): the liquid nitrogen quick freeze, can make food agile through 0 ℃ ~ 5 ℃ maximum ice crystal growth zone, food research staff has done in this regard Of the experiment.
② Link food character: As the liquid nitrogen quick freezing time is short, the liquid nitrogen quick-frozen food can be connected to the maximum processing before the color, smell, taste and nutritional costs. Duan Zhenhua and others with liquid nitrogen on the betel nut held frozen treatment punishment, the results of the interpretation of liquid nitrogen treatment after the punishment of betel nut has a higher chlorophyll content, good charm.
③ material dry consumption is small: the same as the usual loss of dry consumption loss rate of 3 to 6%, while liquid nitrogen quick freeze can be eliminated to 0.25 to 0.5%.
④ set the equipment deployment and power consumption is low, easy to achieve machine and automated assembly line, improve productivity.
Now liquid nitrogen quick freezing is mainly spray freezing, immersion freeze and cold atmosphere freezing three methods, which in turn spray the most widely used.
2, liquid nitrogen in beverage processing applications
Now, there are many beverage manufacturers to accept nitrogen or nitrogen and C02 confused with the traditional C02, the beverage inflatable packaging. Nitrogen-filled high-carbon beverages are less problematic than carbon-only beverages; nitrogen is also a must for beverages such as wine and fruit juice. The benefit of filling liquid nitrogen in non-aerated beverages is that the infusion of a small amount of liquid nitrogen removes oxygen from the top space of each can, leaving the gas in the upper space of the tank inert, thereby extending the shelf life of perishable goods The
3, liquid nitrogen in fruit and vegetable storage and preservation of the application
Liquid nitrogen for the preservation of fruits and vegetables with the advantages of high temperature, adjustable agricultural and sideline products and off-season supply and demand aspects of the contradiction, the loss of storage out. The effect of the atmosphere is to improve the concentration of nitrogen, while controlling the nitrogen, oxygen and C02 gas ratio, and to keep it in a stable state, low the intensity of fruit and vegetable respiration, delay the process of ripening, so that fruit and vegetables to pick the strange picking State and the original nutritional costs, extended fruit and vegetable preservation period.
4, liquid nitrogen in meat processing applications
Liquid nitrogen in the card material meat system, chopping or mixing process to participate in, can be useful to improve the product volume. In the salad dressing, the use of liquid nitrogen can improve meat water retention, stop the oxidation of fat, improve the slice and surface quality; for meat dim sum, meat and other meat processing, not only can make meat mist confused To accelerate the dissolution of protein and enhance water retention, and the unique shape of the product is particularly useful. Other quality meat by the rapid cooling of liquid nitrogen, both in the more long-term link between the hot meat characteristics, gas and ensure the health of the meat and quiet; in the processing technology, no longer have to worry about the impact of temperature on the meat, and processing can not Material temperature, processing time, the impact of seasonal factors, but also make the process in a low oxygen partial pressure, in the range of the product extends the shelf life.
5, liquid nitrogen in food low temperature crushing application
Low-temperature crushing, that is, will cool to the brittle point temperature of the material, under the action of external forces broken into powder course. Low-temperature cooking of food is in recent years to grow up a new food processing skills, the skills of the fur is suitable for processing with aromatic content, high fat content, sugar content and more than the amount of food containing gelatinous substances. With liquid nitrogen held at low temperature crushing treatment penalties can be even the material of bone, skin, meat, shell and so on all the one-time crushing, so that the finished product is small and linked to its useful nutrition. Such as Japan will be frozen after liquid nitrogen seaweed, chitin, vegetables, condiments, etc., into the shredder crushed, can make the finished product fine particle size up to 100μm below, and the basic link to the original nutritional costs. In addition, with liquid nitrogen held at low temperature crushing, but also crushing at room temperature is difficult to crush the material, heat sensitivity and heat susceptible, easy to analyze the material. In addition, liquid nitrogen can be crushed, such as fat and more meat, water and more vegetables at room temperature is difficult to smash the food lattice, and can be made so far have not had new processed foods.
6, liquid nitrogen in food packaging applications
London, UK, a company to open up a simple and practical method of food preservation packaging, is to the food packaging, to the packaging bag to participate in a few drops of liquid nitrogen. When the liquid nitrogen evaporation into gas when the volume of its agile expansion in the bag quickly replace the original most of the gas, out of food due to oxidation caused by deterioration, which greatly extend the food shelf life.
Refrigerated transport is a very important part of the food industry. Development of liquid nitrogen refrigeration skills, growth liquid nitrogen refrigeration trains, refrigerated trucks and refrigerated containers is the current international common growth trend. Economic development of the country for many years the practice of interpretation, liquid nitrogen refrigeration system is the only trade in the machine refrigeration system can compete with the cold storage skills, but also the growth of food refrigeration transport bias.
8, liquid nitrogen in the food industry in other applications
Because of the cooling effect of liquid nitrogen, egg juice, liquid condiments, soy sauce can be processed into a free and can be poured out of granular frozen food, these foods can be readily available and easy to prepare. In the grinding of spices and absorbent food additives, such as sugar substitutes and lecithin, liquid nitrogen is injected into the grinder to cover the cost of the identity, but also increased the grinding yield. Zhou Shunhua and others have proved that the use of liquid nitrogen quenching synergistic high temperature thawing pollen broken with good fruit, broken rate, fast rate and pollen physiological activity linked to a solid, not pollution and so on.
Fourth, liquid nitrogen in the electronics industry applications
1, superconducting skills
Superconductor unique characteristics, it is probably in a wide range of areas to be widely used. Liquid nitrogen instead of liquid helium as superconducting refrigerant to obtain superconductors, so that superconducting technology to a wide range of applications, that is the 20th century, one of the greatest scientific invention.
The superconducting magnetic levitation technique is a superconducting ceramic composed of yttrium barium copper oxide (YBCO). When this superconducting material is cooled to liquid nitrogen temperature (78K, equivalent to -196 ~ C), it changes from normal For superconductivity. The magnetic field generated by the shielding current and the orbital magnetic field mutually exclusion, if the exclusion is greater than the weight of the train, the body can be suspended in the air. At the same time, during the cooling process, a part of the magnetic field is trapped in the superconductor due to the magnetic pinning effect of the superconductor. This trapping magnetic field attracts the orbital magnetic field, and the vehicle body can be stably suspended above the track due to the presence of repulsive force and attraction. And the conventional magnet is repulsive, the difference between the opposite sex and the interaction between the superconductor and the external magnetic field. The following.
2, electronic components manufacturing and testing
Environmental stress screening is the choice of how many typical environmental factors, the amount of environmental stress on the components or machine, the components of the process defects, that is, the production and installation process defects arising out, given the amendment or exchange. Environmental stress screening is more useful for accepting temperature cycles and random vibrations. Temperature cycling test is to accept high temperature, large thermal stress, so that those components of the composition of different materials, due to bad joint, the material itself is not symmetry, defects in the process caused by the hidden dangers of agility, Is 5 ° C / min; the limit temperature is -40 ° C, + 60 ° C; the number of cycles is 8 times. This combination of environmental parameters makes the Weld, the location of the injury, the components of their own defects exposed more obvious. To deal with large quantities of temperature cycle test, you can consider the acceptance of two boxes. In this environment, should be screened at the level.
Liquid nitrogen is a faster and more useful method of shielding and testing electronic components, circuit boards.
3, low-temperature ball milling skills
Low-temperature planetary ball mill is the liquid nitrogen gas source constantly input into the insulation with a planetary ball mill, the cold will be high-speed rotation of the ball mill heat generated in real time, so that the material, grinding ball ball mill is always at Sure of the low temperature environment. In the low temperature environment confused, fine grinding, the development of new products and small quantities of high-tech materials necessary equipment. The product is small, effective, obedient, low noise, widely used in medicine, chemicals, environmental protection, light industry, building materials, metallurgy, ceramics, minerals and other parts. The
4, green cutting skills
Low-temperature cutting is the use of low-temperature fluids such as liquid nitrogen, liquid carbon dioxide and cool breeze and other processing system to the cutting area, resulting in cutting the local low temperature or ultra-low temperature state, the use of low-temperature workpiece under low temperature brittleness, Sex, tool life and workpiece surface quality. According to the difference between the cooling medium, low temperature cutting can be divided into cooler cutting and liquid nitrogen cooling cutting. Low temperature cool air cutting method is through the processing of the tip of the processing site spray -20 ℃ ~ -30 ℃ (or even lower) low temperature air flow, and mixed with trace amounts of plant lubricants (10 ~ 20m 1 per hour), which play Cooling, chip removal, lubrication of the role. Low temperature cooler cutting Compared with traditional cutting, you can probably improve the processing of obedience, improve the surface quality of the workpiece, and almost no pollution to the environment. Japan's Yasuda Industrial Co., Ltd. processing center accepted in the motor shaft, the middle of the bar shaft inserted into the layout of the adiabatic duct, the use of low temperature cool air -30 ℃ leading to the blade. This layout greatly improves the cutting conditions and facilitates the implementation of low temperature cooler cutting processes. Yokogawa Yasuji studied the cooling of the cool air in turning and milling. In the milling test, the water-based cutting fluid, the normal temperature wind (+10 ℃) and the cool air (-30 ℃) were respectively adopted. The results showed that the durability of the tool was improved obviously when the cooler cutting was accepted. In the turning test, the cooler (-20 ℃) cutting tool wear rate than normal temperature (+20 ℃) cutting significantly down.
Liquid nitrogen cooling cutting is important there are two applications, one is the use of bottled pressure to liquid nitrogen cutting fluid as direct injection to the cutting area; the other is the use of liquid nitrogen heat evaporation cycle to indirectly cool the tool or workpiece. Now low temperature machining is mainly used in titanium alloy, high manganese steel, hardened steel and other difficult processing of materials processing. KPRaijurkar accepted H13A carbide cutting tools, and liquid nitrogen circulating cooling tool cutting method on the titanium alloy was held at low temperature cutting test, the test results commentary, compared with the traditional cutting method, tool wear significantly eliminated cutting temperature 30% The workpiece surface processing quality has been greatly improved. Wan Guangmin acceptance of indirect cooling method for high-manganese steel held a low-temperature cutting test results, the results of the interpretation of indirect cooling method to accept low-temperature processing of high manganese steel, the tool hit by the combat force, tool wear reduction, work hardening signs improved , The workpiece surface quality has also improved. Wang Lianpeng and others to accept the liquid nitrogen spray method in the CNC machine tools on the low-temperature machining 45 hardened steel, test results commentary, to accept liquid nitrogen spray low-temperature processing 45 hardened steel can improve tool durability and improve the workpiece surface quality.
In the liquid nitrogen cooling processing state, the cemented carbide material can link its bending strength, fracture toughness and impact strength, its hardness increases with the temperature decreases, so the carbide cutting tool material in the liquid nitrogen cooling can be about Its excellent cutting performance, and the same as at room temperature, its performance depends on the number of bonded phase. To deal with high-speed steel, with the temperature of the low, its hardness increases and anti-strike strength is low, but in general can link a better cutting performance. He studied the processing of some materials at low temperature to improve their machinability, selected low carbon steel AISll010, high carbon steel AISl070, bearing steel AISIE52100, titanium alloy Ti-6A 1-4V, cast aluminum alloy A390 five kinds of materials, The low temperature steel brittleness, low temperature cutting can be obtained as a result of processing; to deal with high carbon steel and bearing steel, the application of liquid nitrogen cooling can inhibit the cutting zone temperature and tool wear rate; in the cutting casting Aluminum alloy, the application of low-temperature cooling can improve the hardness of the tool and the tool against silicon phase abrasive wear, in the processing of titanium alloy, while low-temperature cooling tools and workpieces, can be useful to reduce the cutting temperature and elimination of titanium and tooling between the chemical Affinity.
5, liquid nitrogen other areas of application
Jiuquan satellite production of central special combustion station production of liquid nitrogen, it is the rocket fuel propellant, a lot of liquid nitrogen with high pressure to the rocket fuel into the combustion chamber.
Used in high-temperature superconducting power cable development; used in emergency repair in the liquid pipe frozen; used in the material of low temperature stability and low temperature quenching; liquid nitrogen cold equipment skills (thermal expansion and contraction signs in the industry application) is also widely used ; Liquid nitrogen artificial rainfall technology; liquid nitrogen drainage technology real-time drop into the spray, is constantly in-depth study. Under the nitrogen gas to take off the fire, the fire was agile destruction, while eliminating the gas explosion damage. Why liquid nitrogen: because of cooling faster than other methods, and does not react with other substances from the chemical reaction, greatly reducing the space, providing a dry atmosphere, it is environmentally friendly (liquid nitrogen directly after the use of volatile gas Return to the atmosphere, will not leave any pollution), it is simple and convenient to use.
Through the above description of the liquid nitrogen industry technology development, I believe you have a certain understanding of liquid nitrogen. My company mainly produces sales PCHAO liquid nitrogen tank, complete model, please contact us Tianchi liquid nitrogen tank products for more information, we wholeheartedly at your service.
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