1, oxygen element
Oxygen, a nonmetallic element of group 16 in the second period of the periodic table, has an element symbol o and an atomic number of 8, and its relative atomic mass is 15.9994. Oxygen is the most abundant and widely distributed element in the earth's crust, and it is also the most important element in the biological and abiotic worlds, with a content of 48.6% in the earth's crust. Elemental oxygen accounts for 20.9% in the atmosphere.
2. Carbon element
Carbon is a nonmetallic element with chemical symbol C, which is stable at room temperature, difficult to react and extremely low in toxicity to human body. It can even be safely ingested in the form of graphite or activated carbon, which is located in the second periodic group IVA of the periodic table of elements. Carbon has various structures and can exist in the form of simple substance with various properties, such as crystalline carbon, amorphous carbon and transition carbon.
3. Hydrogen
Hydrogen, a chemical element with the symbol H, ranks first in the periodic table of elements. Hydrogen usually exists in the form of hydrogen, which is colorless, tasteless and odorless. It is a highly flammable gas composed of diatomic molecules, and hydrogen is the lightest gas. The explosion limit of hydrogen is 4.0% to 74.2%.
Industrial production of oxygen:
1, liquid-air separation method
Low temperature and pressure make air become liquid and then evaporate. Because the boiling point of liquid nitrogen ‐ 196℃ is lower than that of liquid oxygen (‐ 183℃), nitrogen first evaporates from liquid air, and the rest is mainly liquid oxygen.
The main components in the air are oxygen and nitrogen. Using the different boiling points of oxygen and nitrogen, the process of preparing oxygen from air is called air separation.
2. Membrane separation technology
Membrane separation technology has developed rapidly. Using this technology, oxygen-enriched air with high oxygen content can be obtained by letting air pass through a film with oxygen-enriched function under a certain pressure. Using this membrane for multistage separation, oxygen-enriched air with oxygen content greater than 90% can be obtained.
3, molecular sieve oxygen method (adsorption method)
Using the characteristic that nitrogen molecule is larger than oxygen molecule, oxygen is separated from air by special molecular sieve. First, dry air is forced by the compressor to enter the vacuum-pumping adsorber through the molecular sieve, and nitrogen molecules in the air are adsorbed by the molecular sieve.
Oxygen enters the adsorber. When the oxygen in the adsorber reaches a certain amount (pressure reaches a certain level), the oxygen outlet valve can be opened to release oxygen.