Carbon DIoxide, CO2, or Super-Gas?

Cryo-Source is a trusted supplier of carbon dioxide to Portland and surrounding areas.

The majority of people not involved the industrial gas industry recognize carbon dioxide, CO2, as the gas used to carbonate soft drinks and as the chemical in fire extinguishers. But CO2 is utilized in so many different forms that it is actually one of the most versatile gases available

Brief History

CO2 was discovered in the early 1600’s as the off gas of burning wood by Jan Baptista von Helmont, a scientist in Finland. In the mid 1700’s a chemist in England, Joseph Priestly, found that mixing water and CO2 being expended from a fermentation process created sparkling water which changed the taste of water and initiated the start of the soft drink industry.

One of the characteristics of the gas that was found was its ability to be easily liquefied. This resulted in it becoming the first commercial industrial gas to be offered as a packaged gas. As more was understood, CO2 became the only gas sold and utlizied in all three of its phases – gas, liquid and solid.

Gas

For those involved in the gas industry, CO2 is most commonly associated as a refrigerant in the food and beverage industry and as a shielding gas in welding. There are also additional unique properties of CO2 that contribute to its versatility .

The most fitting example is when CO2 comes in contact with water and it forms carbonic acid. Although it is not a very powerful acid, it is an acid nonetheless and can be used to adjust the pH in some cases where the pH is an important system parameter. This is prominent in certain industries such as paper production, textiles, and water treatment processes. One more plus is that carbonic acid is not stored as an acid (such as sulfuric or hydrochloric acids). As mentioned, the CO2 needs water to form the acid so it remains CO2 until needed and is not considered hazardous like other acids.

Liquid

CO2 is stored as a liquid regardless of the container. The pressure in an uninsulated CO2 cylinder is somewhere around 800 psig depending on the ambient temperature. The outcome of this is that any application using liquid CO2 has be under pressure. Employees in the oil industry are aware of CO2 replacing water in enhanced oil recovery (EOR) where the liquid is put in a blend with sand or sand like substance (proppant) and propelled through an oil well to recover oil that is stuck between rock layers. EOR is a blanket term to describe different applications but the most prominent is fracking. Here the proppant is forced into the oil rich rock through man made fissures. As a result, the rock fractures and the trapped oil is released. When using CO2 as an alternative to water, its natural expansion of volume from liquid to gas helps enlarge the fissure and recover an additional amount of oil.

It is not commonly known that liquid CO2 is also used in the dry cleaning industry. In a special high pressure washer, liquid CO2 is used with a stain remover. The clothes are then washed regularly employing turbulence to clean the wash. When the cycle is completed, the dirt, grime and stain remover are separated from the liquid CO2. The liquid CO2 is then removed to be used again and the laundry is removed clean and dry since no water was used.

Every chemical (element or compound) has a state in which the three phases (gas, liquid and solid) have the same properties and is reached through modification of temperature and pressure; this is called the supercritical state. The supercritical state of CO2 can be created in a specifically designed processor. When in its fluid phase, CO2 is a great solvent and is utilized in the extracting of fragrances and color from flowers and plants. This method calls for unique tools and equipment and is executed under high pressure.

Solid

Solid CO2 or dry ice is applied in a wide variety of methods as a coolant. When liquid CO2 is transported through a high pressure line and discharged through special nozzles, it immediately becomes CO2 snow and is applied in food refrigeration and freezing. Dry ice pellets replace regular ice in bins that hold perishables on long trips via roadways.

Very small cuts of dry ice are (about the size of a grain of rice) employed as an abrasive to eliminate coating on surfaces without causing damage the surface itself by shooting the rice size pellets through a blasting lance. This is popular in the aircraft industry where the airplane’s bodies need to remain unharmed and not be damaged from sand blasting. Another advantage is that the removed coating does not have to be separated from the abrasive as the pellets sublimate to CO2 gas leading to a cleanup that is quite easy.

Labeling CO2 as a super-gas may be debatable, but it is certainly the most versatile gas available in the industrial gas market.

For more information on how you can get carbon dioxide in Portland for any of your specialty gas operations, call Cryo-Source at 503-235-0168 or at paulb@industrialsource.com.

John Segura, PE

About the Author

John Segura is a licensed Professional Engineer and a seasoned executive in the industrial gas industry. He has over 30 years of experience covering sales, marketing and operations both domestic and international. Segura has led teams of engineers and technicians as an R & D manager for major gas companies. His work lead him to running the marketing efforts of technology worldwide industrial gas suppliers. He still remains in the industry but now as a consultant on the business specializing in operations, applications and marketing.