1, evaporation method
Evaporation is the process of separating carbon dioxide from air and then condensing it into a solid. This method requires the use of special equipment, such as carbon dioxide absorption tower and vacuum pump.
First, the liquid carbon dioxide in the evaporator is heated and evaporated into gas. Then, the gas is pumped out by a vacuum pump and cooled into a liquid state by a cooler. Finally, the liquid carbon dioxide is condensed into solid dry ice by a decompression evaporator.
2. Calcination method
Calcination method is that quicklime CaO reacts with coke C at high temperature to generate carbon monoxide CO and carbon dioxide CO2, of which carbon dioxide is the dry ice we need. This method requires the use of a high temperature furnace and a catalyst.
Firstly, quicklime and coke are put into a high-temperature furnace, and carbon monoxide and carbon dioxide are generated after heating reaction. Then, the generated carbon dioxide gas is collected by a collector and cooled into a liquid state by a cooler. Finally, the liquid carbon dioxide is condensed into solid dry ice by a decompression evaporator.
Precautions for using dry ice are as follows:
1, dry ice will evaporate and sublimate rapidly at room temperature, so it needs to be stored at low temperature. If there is no suitable storage equipment, dry ice should avoid exposure to sunlight or near heat sources.
2. When using dry ice, you should wear appropriate protective equipment, including gloves, scarves and glasses. Because the gas after evaporation of dry ice may cause irritation to eyes, nose and throat. Although dry ice looks like ice, it is actually colder than ice and more likely to cause severe frostbite. Therefore, never touch or try to pick up dry ice.
3. Because dry ice is an excellent coolant, but it is also a flammable substance, it should be avoided to be mixed with flammable substances during use. Dry ice is fragile and easily broken. Therefore, be very careful when handling and handling dry ice to avoid its damage.
4. Dry ice will absorb a lot of heat and produce a lot of carbon dioxide gas, so it is not recommended to use it in a closed environment. The effect of dry ice depends on the ambient temperature. If the ambient temperature is too high, the effect of dry ice may be reduced.