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Conventional industrial gases

Carbon dioxide

Written words: [big] [medium] [small] 2015/12/11 browsing times: One thousand eight hundred and forty     

 Carbon dioxide

What is carbon dioxide?

Carbon dioxide is a common compound in air. The reaction of carbon and oxygen yields its chemical formula of CO2. A carbon dioxide molecule consists of two oxygen atoms and a carbon atom through a covalent bond.

At room temperature, carbon dioxide is a colorless, odorless, non combustible and non flammable gas. It is more dense than air, slightly soluble in water and reacts with water to form carbonic acid. Solid carbon dioxide is commonly known as dry ice after compression. In industry, it can be decomposed by calcium carbonate.

Carbon dioxide is considered to be the main source of the greenhouse effect. At present, its content in the atmosphere is about 400ppm, which is 42% higher than that in 1750 before the industrial revolution.

application area

Carbon dioxide has a very wide range of uses in various sectors of the national economy. Carbon dioxide products are mainly extracted and recovered from synthetic ammonia, hydrogen gas, lime gas, lime gas, acid gas, ethylene oxidation side reaction gas and flue gas. The purity of commercial products is not less than 99% (volume).
Carbon dioxide can be injected into the beverage, increasing pressure, adding bubbles to the beverage and increasing the taste of the drink, such as soft drinks and beer.

• solid carbon dioxide (or dry ice) can vaporize at room temperature and absorb a lot of heat, so it can be used for rapid food freezing.

The weight of carbon dioxide is heavier than air and does not support combustion. Therefore, many fire extinguishers use their characteristics to extinguish fire by producing carbon dioxide. The carbon dioxide extinguisher is used directly to extinguish carbon dioxide by liquefaction. Besides these characteristics, it also has the advantage of not leaving solid residues after fire.

Carbon dioxide can also be used as a protective gas for welding, and its protection effect is not as good as that of other rare gases (such as argon), but the price is much cheaper.

CO2 laser is an important source of industrial laser.

Carbon dioxide can be used to make wine, and carbon dioxide creates an environment of anoxia, which helps prevent bacteria from growing in grapes.

Carbon dioxide can control the pH value, the swimming pool adds carbon dioxide to control pH value, add carbon dioxide to maintain pH value does not rise.

Carbon dioxide can be used in soda industry and sugar industry.

Carbon dioxide can be used as blowing agent in plastics industry.

Dry ice can be used for artificial rain, smoke effects on stage, special effects in food industry, food and so on.

Dry ice can be used to clean up nuclear industry equipment and printing rolls.

Dry ice can be used in automobiles, ships, aviation, space and electronics industries. Liquid carbon dioxide is decomposed into gas and decomposed by volume. It completely eliminates the complicated post-processing process caused by traditional solvents.

CO supercritical fluid extraction technology. When the temperature is above 31 Tc and the pressure is higher than the critical pressure (Pc) 3MPa, the properties of carbon dioxide will change. The density will be close to the liquid, the viscosity is close to the gas, and the diffusion coefficient is 100 times that of the liquid. Therefore, the carbon dioxide has a strong solvability. It can dissolve many substances and extract the effective components. Products can extract substances which were not extracted by chemical methods in the past, and are cheap, non-toxic, safe and efficient. It is suitable for chemical, pharmaceutical, food and other industries.

Human harm

The density of carbon dioxide is larger than that of air. When carbon dioxide is small, it is harmless to human body. However, when it exceeds a certain amount, it will affect the respiration of people (other organisms). The reason is that the concentration of carbonic acid in blood increases, the acidity is enhanced, and acidosis is produced. When the volume fraction of carbon dioxide in air is 1%, it is stuffy, dizzy and palpitated. 4%-5% feels dizzy. More than 6% make people unconsciousness, breathing gradually stop and die.

Because carbon dioxide is heavier than air, it has a higher concentration in low-lying areas. When drilling or digging piles, if the ventilation is bad, the suffocation of the bottom staff will be caused. The normal content of CO is 0.04%. When the concentration of CO is 1%, it can make people feel depressed, dizzy and palpitate. When reaching 4%~5%, people will feel asthma, headache and vertigo. When reaching 10%, it will cause serious disorder of human function and make people lose consciousness, be unconscious and stop breathing. Substances that should be avoided:

All kinds of metal dust (such as magnesium, zirconium, titanium, aluminum, manganese): when suspended in carbon dioxide, it is easy to ignite and explode.

Inhalation of high concentration of carbon dioxide can cause coma and brain hypoxia. When the carbon dioxide content in the atmosphere exceeds 1%, people will have mild dizziness; when more than 3%, breathing difficulties will begin; when more than 6%, they will suffer severe hypoxia, asphyxia or even death.

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