Liquid carbon dioxide is carbon dioxide gas that is highly compressed and cooled to a liquid form. Carbon dioxide exists as a liquid below the critical temperature of 31C and above the triple point with a temperature of-56.6 C and 4.18 bar.
Generally, CO2 gas is transported, stored and handled in liquid form, either in cylinders or non-insulated storage tanks at a pressure of 45-65 bar or refrigerated tanks at temperatures between -35 C and -15 C and pressures of 12 to 25 bar. Demand for liquid CO2 in various industries has grown tremendously. This is a reflection of the diverse applications of this gas.
Liquid carbon dioxide is widely used in the entertainment industry to achieve special effects. With liquid co2, many special effects are easier and economical to achieve. Without it, it would require expensive pyro technique equipment to produce these effects:
Haze effects: Liquid CO2 is used to create homogenous cloud effects in TV production. These clouds are used to reveal lighting beams in a music concert. The gas serves to accentuate the effect of spotlights. The cloudy effect is produced by passing compressed c02 through a reservoir of highly refined mineral oil.
Fog effects: You have seen movies with foggy scenes but they were probably filmed in a sunny desert. Liquid carbon dioxide is used together with fog machines to produce a low-lying fog effect. Liquid CO2 is used to cool theatrical fog produced by the fog machines. The fog remains close to the ground when it is cold but when it warms it disperses evenly.
The importance of pressurized C02 in the food industry cannot be underscored enough. The food industry largely relies on this liquid gas for refrigeration, preservation, storage and softening.
Cooling agent: Liquid co2 is used as an important cryogenic cooling agent. It is used directly as a food preserve and in cooling applications where it maintains the food at constant at temperature. Liquid carbon dioxide is also used during the transportation of ice cream. It is preferred because of its high volumetric cooling capacity.
Softening drinks: Compressed carbon dioxide gas is largely used in the production of soft drinks. Carbonation of drinks first happened by natural fermentation, but today bottled drinks are softened and preserved using pressurized co2. Liquid C02 is also used to remove caffeine from coffee because it is a versatile solvent.
Liquid Carbon dioxide is used as a fire extinguisher because of its anti- flammable properties. The gas works by starving the flames of oxygen, which is the gas that supports burning. Fire extinguishers used to put out electrical fires are specifically filled with liquid carbon dioxide. This is because apart from putting out the fire by eliminating oxygen, the pressurized gas cools the burning surfaces preventing further damage.
In oil recovery, the liquid is pumped into oil wells where it becomes miscible with the oil. It reduces the viscous nature of oil and causes it to flow easily to the point of removal.
Liquid co2 is a versatile gas with many applications. Perhaps the most prominent ways it is used today is in the food and entertainment industries.