The history of dry ice can be traced back to 1823. Two people named Faraday and Peter in Britain liquefied carbon dioxide for the first time, and then Quirrell in Germany successfully produced solid carbon dioxide in 1834. But it was only used for research at that time and was not widely used.
Chinese name
dry ice
English name
dry ice
Another name
Solid carbon dioxide
chemical formula
carbon dioxide
molecular weight
44.0095
Chemical abstracts service registration number
124-38-9
melting point
-78.5 (sublimation)
boiling point
-56.6(0.52MPa？ )
water-solubility
Insoluble in water
density
The density of dry ice is higher than that of ordinary ice.
external
White ice-like solid
App application
Artificial rainfall, stage performance
Safety description
Not higher than boiling point
Risk code
If it is higher than -78 degrees Celsius under sealed conditions, dry ice may explode.
catalogue
1 function
get angry
enter
2 Basic information
3 use history
4 process
5 Scope of application
Cleaning of mould industry
Petrochemical electric power
Food and pharmaceutical industries
press
Automobile and ship industry
Electronics and nuclear industry
Cosmetic industry
food service industry
Refrigerated transportation field
Entertainment field
Fire field
6 clean technology
Cleaning principle
purifying equipment
Cleaning machine
7 preventive measures
Safe contact
keep
8 Mars exploration
characteristic
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get angry
You can see white fog when dry ice sublimates.
Carbon dioxide is invisible. It's not smoke, it's fog. When carbon dioxide changes from solid to gas, it absorbs a lot of heat, which makes the temperature of the surrounding air drop rapidly, and the air temperature drops accordingly. Its solubility in water vapor becomes smaller, and the water vapor liquefies and releases heat, turning into small water droplets, which is fog. This is the same as the "white fog" of popsicles in summer. It's all water droplets, not other gaseous substances.
That is, we see white fog instead of white smoke.
enter
The temperature of dry ice is much lower than that of water, so it is equivalent to heating dry ice, which absorbs heat and sublimates, reducing the temperature of water and even freezing it.
Basic information
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Carbon dioxide phase diagram
Molecular weight: 44.0 1
The solubility with water is 1: 1.
Density (solid): 1560 kg/m3 (-78℃)
Boiling point: -57℃
Melting point: -78.5℃
Triple point -56.6℃ 5. 17 * 10 5 Pascal.
Critical point 3 1℃ 7.37 * 10 6 Pascal
Colorless and odorless gas.
Soluble in water (volume ratio: 1: 1), partially generating carbonic acid.
The liquid-gas ratio is 8.726SCF (gas) /LB (liquid-17.8℃, pressure 2 1kg/cm).
The liquid-solid ratio is 0.46 (-17.8℃) 0.57 (-48℃) [1]?
Usage history
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Molecular model of dry ice
The United States established the successful industrialized mass production of dry ice in 1925. At that time, the name of the finished product was dry ice, but its official name was 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. ..
procedure
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In the process of dry ice cleaning, dry ice cleaning uses the kinetic energy of compressed air.
Dry ice cleaning process
Drives DSJet dry ice in dry ice cleaning machine. Dry ice is mixed with gas through professional equipment, and then sprayed on the surface of objects through pipelines and professional nozzles, thus achieving the effect of cleaning and decontamination.
applied range
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Cleaning of mould industry
Tire mold, rubber mold, polyurethane mold, polyethylene mold, PET mold.
Dry ice cleaning ceiling mould in automobile industry
Foam mold, injection mold, alloy die casting mold, hot core box and cold core box for casting can remove residual resin, invalid peeling layer, carbonized film forming agent and oil stain, and open exhaust holes. After cleaning, the mold is as bright as new.
DSJet dry ice 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.
Petrochemical electric power
Clean the main fan, air compressor, fan cover, steam turbine, blower and other equipment and all
DSJet dry ice cleaning power plant rotor
Removing coking and carbon deposition in heating furnace and reactor. Clean the PVC resin on the heat exchanger, remove oil stains, rust spots, hydrocarbons and dirt on the surfaces of various pressure vessels such as compressors, storage tanks and boilers, clean the reaction kettle and condenser, clean the complex and clean the furnace tubes. 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.
Food and pharmaceutical industries
DSJet dry ice cleaning printer
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 and other equipment.
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.
press
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.
Automobile and ship industry
Cleaning doorskins, roofs, carriages, car bottoms and other oil stains will not cause water pollution.
Dry ice particles
; 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 problem of carbon deposition within 10 minute, saving time and reducing cost, and the scale removal rate reaches 100%.
. 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.
Electronics and nuclear 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. 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 flow
Dried icicles are used in the food industry.
Gas engine conversion system. Can work directly in the body, saving time.
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.
Cosmetic industry
Some dermatologists treat acne with dry ice. This treatment is called cryotherapy because it will slightly freeze the skin.
There is a frozen substance for treating acne, which is mixed with ground dry ice, 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.
food service industry
1, add dry ice to wine, cocktail or beverage to make it cool and delicious.
Effect of staged dry ice
Smoky, it's refreshing.
2. Add dry ice when making ice cream, and the ice cream will not melt easily. Dry ice is especially suitable for cold storage and transportation of takeaway ice cream.
3. Adding dry ice to seafood dishes in star-rated hotels and restaurants can create a white smoke landscape and improve the level of banquets, such as making lobster sashimi.
4, lobster, crab, shark fin and other seafood 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.
Refrigerated transportation field
1, cryogenic refrigeration for medical use and cryogenic transportation of special drugs such as plasma and vaccines.
2. Long-distance and short-distance transportation of electronic cryogenic materials and precision components.
3. Fresh-keeping transportation of high-grade foods such as high-grade beef and mutton.
Entertainment field
Widely used in stage, theater, film and television, wedding, celebration, party and so on. There are countless special effects classic plays made of dry ice in China and even in the world.
Fire field
Dry ice is used to put out fires, 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.
clean technologies
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Dry ice cleaning has been widely used in foundry industry all over the world, and most foundry industries have changed to dry ice cleaning to clean sand core molds and fixed molds.
Cleaning principle
"Energy transfer" Dry ice impacts the surface to be cleaned at a high speed, and the impact kinetic energy is dissipated, and the dry ice particles and the surface to be cleaned undergo extremely rapid heat transfer, and carbon dioxide instantly sublimates.
"Cryogenic cracking". The temperature difference between two different materials with different thermal expansion coefficients will destroy the combination between the two materials. Dry ice particles (-78.5℃) impact the surface of the treated object, causing the dirt to freeze, embrittle and burst, resulting in "cracking", which affects the mechanical properties of the attached dirt.
"Micro-explosion". After the dry ice particles drill into the dirt gap, they sublimate within a few thousandths of a second, and the volume instantly expands by 600-800 times, stripping the dirt from the surface of the object.
In the process of dry ice cleaning, compressed air is used as the power to spray dry ice particles on the surface of the object to be cleaned at supersonic speed, instead of relying solely on the kinetic energy of dry ice particles, the ultra-low temperature performance of dry ice is used to achieve the purpose of decontamination.
purifying equipment
Dry ice cleaning equipment can usually be divided into two parts:
1. dry ice granulator. Liquid CO2 is made into dry ice particles with certain specifications, which are usually high-density dry ice particles with a diameter of 3mm and a length of 2.5 mm-10 mm. ..
2. Dry ice high-pressure cleaning machine. Generally, the equipment needs a clean compressed air source of more than 4.0bar and more than 3m3/min. Driven by compressed air, the high-density dry ice particles loaded into the cleaning machine are mixed with compressed air through a specially designed spray gun system and accelerated, and sprayed onto the surface of the cleaned object.
As required: ① Only buy dry ice cleaning machine. The purchased dry ice particles are loaded into dry ice cleaning machine for cleaning operation. (2) Buy dry ice granulator and dry ice cleaning machine, but use them separately. The dry ice granules produced by the dry ice granulator are stored in special sealed containers, transported to the construction site and loaded into dry ice cleaning machine for cleaning. ③ The dry ice granulator and dry ice cleaning machine are combined into a system for use.
dry ice
Cleaning machine
Dry ice cleaning can be done on the spot. This advanced cleaning method can not only save working hours, but also greatly reduce downtime. Compared with the old sandblasting, it not only has no worry about wear, but also saves the time of remolding.
Dry ice cleaning removes the demoulding layer and residual materials on the mold. When the mold is at high temperature and online, these accumulated dirt can be easily removed. This cleaning method can shorten the cleaning downtime by 80%-95%. Because there is no wear in the cleaning process, the size of the precision mold will not be destroyed. In addition, the "micropore" can be opened for cleaning without manual drilling of the exhaust hole.
Matters needing attention
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Safe contact
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 slight or extremely serious frostbite damage. Dry ice cannot be used in sealed places such as cars and cabins, because the sublimated carbon dioxide will be denser than oxygen, so it will squeeze out oxygen, which may lead to shortness of breath or even suffocation!
Never let children touch dry ice alone! !
The temperature of dry ice is extremely low, please don't put it in your mouth to prevent frostbite! !
When taking dry ice, you must use thick cotton gloves, clips and other shelter (plastic gloves have no shelter! ! )
Please use dry ice in a well-ventilated place and avoid in a closed space with dry ice! !
Dry ice cannot be mixed with liquid.
Tip: Use dry ice correctly and safely to avoid injury.
keep
Put dry ice in an incubator: an incubator with good insulation effect can slow down the sublimation of dry ice.
Because the pressure generated by sublimation of dry ice will cause explosion, it is not allowed to store dry ice in a closed incubator.
Mars exploration
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For the first time, scientists have successfully discovered the flowing material in the deep valley of Mars-Australia and Mexico.
Dry ice cleaning equipment
Dr Nick Hoffman, a geologist at Irvine University, 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.
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, fire
dry ice
This star is absolutely still, if you don't notice its dust storm. 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." [2]?
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reference data
1.？ Chemistry for Nine-year Compulsory Education, 2nd edition, 9th grade last semester, Shanghai Education Press, August 2007, ISBN 978-7-5320-8481-4/G8506, pages 109,1kloc-0/2.
2.？ There is a lot of dry ice on Mars?