Commonly known as dry ice.
Evaporation at room temperature/
This is what you see. /
Dry ice is solid carbon dioxide. At normal temperature and pressure of 6079.8 kPa, carbon dioxide condenses into colorless liquid, and then rapidly evaporates at low pressure, and then condenses into dense ice-like solid matter. Its temperature is MINUS 78.5℃, which is dry ice. The cold storage capacity of dry ice is more than 1.5 times that of water ice. After absorbing heat, it sublimates into carbon dioxide gas, which has no residue, toxicity and odor, and has sterilization effect. Direct gasification without liquefaction after heating. Dry ice is the solid state of carbon dioxide. Because the temperature of dry ice is very low, the temperature is MINUS 78.5 degrees Celsius, so it is often used to keep objects in a frozen or low temperature state. ?
At room temperature, when carbon dioxide gas is pressurized to about 10 1325Pa, a part of steam will freeze into snowflake-like solid carbon dioxide when it is cooled to about -56℃. The gasification heat of solid carbon dioxide is very high, which is 364.5 J/g at -60℃. During atmospheric gasification, the ambient temperature can be reduced to about -78℃ and no liquid will be produced, so it is called "dry ice" [1].
[Edit this paragraph] Physical properties of dry ice
Molecular weight of carbon dioxide phase diagram? 44.0 1
Density (solid)? 1560kg/m3 (-78℃)
Melting point? -57℃
Freezing point? -78.5℃
The triple point of dry ice molecular model is -56.6℃? 5. 17 * 10 5 Pascal?
Critical point? 3 1℃? 7.37 * 10 6 Pascal
Character; Role; letter
Colorless and odorless gas with sour taste.
Dissolution situation
Soluble in water (volume ratio: 1: 1), partially generating carbonic acid.
The ratio of liquid to gas? 8.726 standard cubic feet (gas)/pound? (liquid-17.8℃, pressure 2 1 kg/cm)
The ratio of liquid to solid? 0.46(- 17.8℃)0.57(-48℃)
[Edit this paragraph] Dry ice history
The history of dry ice can be traced back to 1823, when two British men named Faradi and Peter liquefied carbon dioxide for the first time, and then Ciroli successfully produced solid carbon dioxide in 1834. But it was only used for research at that time and was not widely used. The United States established the successful industrialized mass production of dry ice in 1925. At that time, the finished product was called dry ice, which is now a common term, but its official name is solid carbon dioxide. 1928, Japan obtained the manufacturing and sales rights from dry ice co., ltd, and established Japan dry ice co., ltd, the predecessor of showa carbonic acid co., ltd. ..
[Edit this paragraph] Application scope of dry ice
Dry ice is widely used in food, sanitation, industry and catering. Mainly includes:
1. What is the application scope of dry ice in industrial molds?
Tire mold, rubber mold, polyurethane mold, polyethylene mold, PET mold, foaming mold, injection mold, alloy die casting mold, hot core box for casting and cold core box can remove residual resin, invalid peeling layer, carbonizing film agent and oil stain, and can open air holes. After cleaning, the mold is as bright as new.
On-line cleaning does not need to cool and disassemble the mold, which avoids the corrosion and damage of the mold by chemical cleaning method, the mechanical damage and scratch of the mold by mechanical cleaning method, and the decline of mold accuracy caused by repeated loading and unloading. Crucially, the two most time-consuming steps of removing the mold and waiting for the mold to cool can be omitted, and the downtime can be reduced by about 80%-95%.
Benefits of dry ice cleaning:? Dry ice cleaning can reduce downtime; Reduce equipment damage; Very effective cleaning of high-temperature equipment; Reduce or reduce the use of solvents; Improving the safety of staff; Improve maintenance efficiency; Reduce production downtime, reduce costs and improve production efficiency.
2. What is the application scope of dry ice in petrochemical industry?
Clean the main fan, air compressor, fume hood, steam turbine, blower and other equipment to remove coking and carbon deposition in various heating furnaces and reactors. Clean the PVC resin on the heat exchanger; Remove oil stains, rust, hydrocarbons and dirt on the surfaces of various pressure vessels such as compressors, storage tanks and boilers; Cleaning the reaction kettle and condenser; Complex biological purification; Furnace tube cleaning, etc.
3. What is the application scope of dry ice in food and medicine industry?
It can successfully remove baking residues, colloidal substances and oil stains in the oven, as well as the mixture of fresh products before baking. Effectively clean ovens, mixing and stirring equipment, conveyor belts, molded products, packaging equipment, stoves, stoves, containers, rollers, refrigerator inner walls, biscuit stoves, etc.
Benefits of dry ice cleaning: put an end to the use of harmful chemicals, and avoid production equipment contacting with harmful chemicals and generating secondary garbage; Prepare or remove bacteria such as Salmonella and Listeria, and disinfect and clean more thoroughly; Eliminate the damage of water jet cleaning to electronic equipment; Minimum equipment decomposition; Reduce downtime.
4. What is the application scope of dry ice in printing industry?
It is difficult to remove ink, and the accumulation of ink on gears and guide rails will lead to poor printing quality. Dry ice cleaning can remove all kinds of oil-based and water-based inks and varnishes, clean up oil stains, accumulated inks and dyes on gears, guide rails and nozzles, and avoid the discharge of harmful wastes and solutions and personal injuries caused by harmful solvents.
5. What is the application scope of dry ice in power industry?
Can clean electric boilers, condensers and various heat exchangers; Can directly clean indoor and outdoor transformers, insulators, power distribution cabinets, live wires and cables (below 37KV); Generator, motor, rotor, stator and other parts are clean and free from damage; Clean the rust, hydrocarbon and adhesive powder on turbines, impellers, blades and other parts, without disassembling the blades and readjusting the dynamic balance of the blades.
Benefits of dry ice cleaning: effectively decompose pollutants to be cleaned; Because these pollutants are removed, the power loss is reduced; The maintenance cost of external equipment and its basic equipment is reduced; Improve the reliability of power system; Keep the insulator intact and non-abrasive clean; More suitable for preventive maintenance.
6. What is the application scope of dry ice in automobile industry?
Cleaning the doorskin, roof, carriage, car bottom and other oil stains will not cause water pollution; Cleaning of automobile carburetor and removal of automobile surface paint; Remove carbon deposits from the engine. ? If the carbon deposit is treated, it will take a long time to treat it with chemical agents, at least more than 48 hours, which is harmful to human body. Dry ice cleaning can completely solve the carbon deposition problem within 10 minute, save time and reduce cost, and the scale removal rate can reach 100%? .
7. Application scope of dry ice in electronic industry
Clean the grease and dirt inside robots and automation equipment; Clean the integrated circuit board, post-welding flux, pollution coating, resin, solvent coating, protective layer and photosensitive corrosion inhibitor on the printed circuit board.
8. What is the application scope of dry ice in aerospace?
Pre-coating treatment and final assembly of missiles and aircraft; Paint removal of composite molds and special aircraft: engine carbon cleaning; Maintenance and cleaning (especially the landing gear-wheel well area); Depainting of aircraft shells: jet engine conversion system. Can work directly in the body, saving time.
9. What is the application scope of dry ice in shipbuilding?
Hull; Seawater suction valve; Seawater condenser and heat exchanger; The machine room, machinery and electrical equipment are cleaner than ordinary high-pressure water jet cleaning.
10, application scope of dry ice in nuclear industry?
If the nuclear industry equipment is cleaned by traditional cleaning methods such as water, sand blasting or chemical detergent, the media such as water, sand blasting or chemical detergent will also be polluted by radioactive elements, so it takes time and money to treat these secondary polluted media. In the process of dry ice cleaning, dry ice particles are directly sprayed on the object to be cleaned, which instantly sublimates, and there is no problem of secondary pollution. All that needs to be treated is the cleaned waste with nuclear pollution and scale.
1 1. Application scope of dry ice in beauty industry
Some dermatologists use dry ice to treat acne, which is called cryotherapy. Because it will slightly freeze the skin. ?
There is a frozen substance for treating acne, which is made of ground dry ice and ethyl ketone, and sometimes some sulfur is added. Liquid nitrogen and solid dry ice can also be used as cryotherapy materials. Cryotherapy can reduce inflammation. Some time ago, the news reported that Liu Xiang used this cryotherapy to treat acne on his face. This method can reduce the generation of acne scars, but it is not used to remove scars.
12, Application scope of dry ice in food industry
Answer? Adding dry ice to wine, cocktail or beverage is cool and delicious when drinking, and the cup is full of smoke, which is very pleasant. ?
b？ Dry ice is added when making ice cream, so the ice cream doesn't melt easily. Dry ice is especially suitable for cold storage of takeaway ice cream.
c？ Seafood dishes made by star-rated hotels and restaurants, with dry ice, can produce white smoke landscape and improve the banquet level? Like making lobster sashimi.
d？ Lobster, crab, shark's fin and other seafood are frozen and refrigerated. Dry ice will not change water, and it is cleaner than water-cooled storage. Widely used in Europe, America, Japan and other countries.
13, Application scope of dry ice in refrigerated transportation field
Answer? Cryopreservation, medical use and transportation of special drugs such as plasma and vaccines.
b？ Long-distance and short-distance transportation of electronic cryogenic materials and precision components.
C. preservation and transportation of high-grade foods such as high-grade beef and mutton.
14? Application scope of dry ice in entertainment field
Widely used in stage, theater, film and television, wedding, celebration, party effect and so on. For example, some programs in the National Theatre are made of dry ice.
15, application scope of dry ice in fire protection industry
Dry ice is used for fire fighting, such as some low-temperature fire extinguishers, but the application of dry ice in this respect is less, that is, the market level is low;
Precautions for using dry ice:
Remember to be careful every time you touch dry ice. Touch dry ice with thick cotton gloves or other shelter! If it is in direct contact with the skin for a long time, it may cause cell freezing and similar minor or extremely serious burns. Dry ice cannot be used in cars, cabins and other places, because sublimated carbon dioxide will replace oxygen, which may lead to shortness of breath or even suffocation! ?
1. Never let children touch dry ice alone! !
2. The temperature of dry ice is extremely low, please don't put it in your mouth to prevent frostbite! ! ?
3. When taking dry ice, you must use thick cotton gloves, clips and other shelters? (Plastic gloves have no shielding effect! ! )?
4. Please use dry ice in a well-ventilated place and avoid in a closed space with dry ice! !
5. Dry ice cannot be mixed with liquid.
Tip: Use dry ice correctly and safely to avoid injury. ?
Symptoms and treatment of frostbite:
What is the definition of frostbite?
Frostbite means that a part of the body is exposed to cold environment for a long time, and its skin and tissue are damaged.
Symptoms:?
You will feel cold and a little red before frostbite.
The skin will lose its color first, but when frostbite gradually forms, it will turn white or grayish yellow, or white with spots.
There may be blisters. Maybe it hurts a little, or maybe you don't even know you have frostbite?
The first symptom of frostbite (chilblain) is tingling, followed by numbness and stiffness, and the affected part is pale; At this time, if it is heated, it can be completely restored. The initial chilblain will develop into superficial chilblain if it is not treated. At this time, the skin and subcutaneous tissue have died, and the skin is still pale or slightly gray, and it feels cold but soft. After thawing, it will be red, swollen and painful, and form a big blister similar to second-degree burn after one to a few days; After a few days, the blisters dry to form a black eschar, which will eventually be replaced by new skin if there is no concurrent infection. ?
Frostbite treatment measures:
Move to a warm place and keep the affected part in warm and dry air. Remove the binding substance to avoid being unable to pull it out when it is swollen. Keep warm in gradually adjusted warm water (38.8~40.5 degrees)?
Don't be exposed to the cold again. Raise the affected part to relieve pain and swelling. Then wrap the affected area with clean gauze and send it to the hospital for treatment; The purpose of first aid is to restore the body fluids bound by cold to normal. Therefore, if we can warm the area around the affected area, it can be cured soon. It is forbidden to directly soak the affected area with hot water or bake it with fire, which will aggravate frostbite. Because massage can cause it, remember not to do massage in the affected area.
Caution-Do not massage, bake or puncture blisters to prevent infection.
[Edit this paragraph] Is there any dry ice on Mars?
For the first time, scientists have successfully discovered movable matter in the deep valley of Mars. Dr Nick Hoffman, a geologist at the University of Melbourne, Australia, found signs of active processes flowing in valleys and rivers in polar regions on the photos of the surface of Mars taken by the Mars Global Probe. Although most scientists think it is liquid water, Dr. Hoffman thinks it is mainly frozen carbon dioxide. If his estimation is correct, NASA's attempt to find liquid water and life on Mars will be doomed to failure.
In the new issue of Space Biology, Dr. Hoffman presented his own new evidence. In spring, when the temperature of Mars is-130℃, ice and snow full of carbon dioxide flow in the ravine. Even the acid in the battery will turn into pebbles at such a cold temperature. It is impossible for water to flow at such a low temperature, so most of the water flowing in the ravine of Mars is carbon dioxide. But there can't be liquid carbon dioxide on Mars, because carbon dioxide will change directly from solid to gas (so-called sublimation). Obviously, "fluid" is an avalanche or ice collapse composed of sand, dust and "boiling" dry ice of stones.
Dr Hoffman pointed out, "This discovery can dispel people's illusions about life on Mars. If all the young gullies on Mars had the same formation mechanism, NASA could not claim that there was life near the surface of Mars. There will be no liquid water on Mars. Although it has been reported many times not long ago that a large amount of water ice has been found on Mars, NASA has not found liquid water. "
Dr. Hoffman believes that the discovery of active "fluid" on Mars itself is an epoch-making discovery, because before that, Mars was absolutely static, if we didn't pay attention to its sandstorms. Gullies on Mars are considered as the most likely choice to find liquid water on Mars today. Many experts from NASA have focused their attention on finding the mechanism, which can explain why gullies are formed under the action of water erosion, but no one has ever seen gullies "flow" before.
Dry ice is solid carbon dioxide. Because the temperature of dry ice is very low, the temperature is MINUS 78.5 degrees Celsius, so it is often used to keep objects in a frozen or low temperature state. Dry ice can quickly freeze objects and reduce the temperature, which has been widely used. Dry ice does not change from solid to liquid when it is dissolved, but sublimates directly from solid to gas, so its melting will not produce any water or liquid, which is why we call it "dry ice".
In 2006, American scientists announced that they had discovered a "dry ice fountain" on Mars, which could spray dry ice hundreds of feet high.
Scientists say that through the camera installed on the Mars probe Odyssey, they found that there is dry ice spewing like a fountain at the South Pole of Mars at a speed of 100 miles per hour.
According to the BBC, photos show that the dry ice ejected from the interior of Mars has brought a lot of dust and left various black marks on the ice sheet.
Scientists explained that the surface of Mars became warmer after being irradiated by the sun, which melted the originally frozen dry ice and formed high-pressure gas, which was ejected at high speed.
Dr Christensen of Arizona State University said, "If you are there, you will find yourself standing on a thick layer of dry ice. And around you, dry ice is still spewing from the ground, spraying hundreds of feet from the ground, bringing a lot of dust. "
Christensen said: "There is no similar phenomenon on earth."