What is steam?
Steam is the gas that occurs when water changes from a liquid state to a gaseous state. Microscopically, it is the phenomenon of H₂O molecules trying to get rid of intermolecular forces (such as hydrogen bonds).
Production of steam
In liquid water, H₂O molecules are repeating the process of collision and separation. When the water molecules are heated, the chemical bonds connecting the molecules start to be broken rapidly, even faster than they can be combined. Eventually, when enough heat is absorbed, some of the water molecules start to become free. These "free" transparent gas molecules are what we know as steam.
Classification of Steam
In terms of form, steam is divided into: wet steam, saturated steam, and superheated steam.
In terms of cleanliness, steam is classified as: industrial steam, clean steam, or pure steam.
Applications of Steam
Steam can be used in food processing plants, oil refineries and chemical plants, etc. Saturated steam can be used as a heating source for fluid heat exchangers, reboilers, reactors, combustion air preheaters, and other types of equipment.
Steam is often used as power (as a drive), typically in the form of a steam turbine. Steam turbines are a critical piece of major equipment for thermal power plants.
Atomized steam is a process long used in the case of mechanical shunts. In some burners, for example, steam is injected into the fuel to maximize combustion efficiency, which reduces the production of hydrocarbons (soot).
During the cold season, low-pressure saturated steam is often used as the primary heat source to keep rooms warm. HVAC coils are often used in combination with steam humidifiers, and air conditioners ensure comfortable indoor temperatures as well as digital control of them.
Principle of pressure steam moist heat sterilization
When sterilized items are placed in high-temperature and high-pressure steam medium, the latent heat is released when the steam meets the cold items. When the temperature rises to a certain temperature, some of the proteins and nucleic acids on the sterilized products are damaged by hydrogen bonding, especially the protein structure--enzymes that bacteria rely on and are necessary for metabolism, which lose their activity under the high temperature and hot and humid environment and eventually lead to the death of microorganisms. At the same time, the hot and humid environment also forces the protein of all microorganisms to coagulate and denature.