Carbon DIoxide, CO2, or Super-Gas?

Rocky Mountain Air Solutions is a trusted supplier of carbon dioxide to Denver and surrounding areas.

Most people not affiliated with the industrial gas industry are familiar with carbon dioxide, CO2, as the gas used to carbonate soda and as the chemical in fire extinguishers. CO2 is used in more forms than any other gas in the industrial gas market making it one of the most versatile products sold

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, discovered sparkling water through the process of combining water and CO2 dissipated from a fermentation process which gave the water a different taste and became the basis for the soft drink industry.

One of the properties of the gas that was found was its ability to be easily liquefied. This led to CO2 being the first commercial industrial gas to be supplied as a packaged gas. Eventually, after learning more about the gas, CO2 became the only gas sold and applied in all three of its phases – gas, liquid and solid.

Gas

Most of us in the industry associate CO2 as a refrigerant in the food and beverage industry and as a shielding gas in welding. Other characteristics make it unique as well .

The best example is when CO2 creates carbonic acid after coming into contact with water. Although it is not a very powerful acid, it is an acid nonetheless and has the ability to adjust the pH in certain applications where the pH is a relevant system parameter. This is the case in specific 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 generate the acid so it remains CO2 until needed and unlike many other acids, is not considered harmful.

Liquid

CO2 is stored as a liquid regardless of the container. The pressure in an uninsulated CO2 cylinder is usually around 800 psig depending on the atmospheric temperature. The outcome of this is that any method using liquid CO2 must be under pressure. Employees in the oil industry are aware can compensate for water in enhanced oil recovery (EOR) where the liquid is combined with sand or sand like substance (proppant) and propelled through an oil well to recover oil that is trapped inside the rock layers. EOR is a wide-ranging term that can refer to several different processes but the most frequent is fracking. In this case a propant is pushed into rocks rich with oil with the use of man-made devices. This leads to the fracture of the rock and the subsequent release of the oil inside of it. When CO2 is used instead of water, its natural expansion of volume from liquid to gas makes the fissure larger and helps recover additional oil.

It is not commonly known that liquid CO2 is also used in the dry cleaning industry. In a specific high pressure washer, liquid CO2 is used with a stain remover. The laundry is treated as in a regular washing machine 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 taken out to be used again and when the clothing is taken out and is clean and not wet since there was no water applied.

Every chemical (element or compound) has a state in which the three phases (gas, liquid and solid) have the same properties and is achieved through proper adjustment of temperature and pressure; this is known as the supercritical state. The supercritical state of CO2 can be created in a specifically designed processor. Because it is an excellent solvent, CO2 in its fluid phase is used to extract 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 used as a coolant in several ways and forms. When liquid CO2 is sent through a high pressure line and passed through special nozzles, it immediately becomes CO2 snow and is applied in food refrigeration and freezing. Dry ice pellets act as a replacement for regular ice in tubs that hold perishables for long over-the-road transport.

Very small cuts of dry ice are (about the size of a grain of rice) used as an abrasive to remove coatings from surfaces without harming the surface itself by launching the rice size pellets through a blasting lance. This is prominent in the aircraft industry in which the body of an airplane must remain intact and not suffer from the harm that sand blasting would cause. An additional benefit is that the removed coating does not have to be separated from the abrasive as the pellets sublimate to CO2 gas resulting in a simple cleanup.

Referring to CO2 as a super-gas may be overstepping the bounds of the definition, but it is certainly the most versatile gas available in the industrial gas market.

To find out more about how you can get carbon dioxide in Denver for any of your specialty gas operations, call Rocky Mountain Air Solutions at (303) 777-6671 or at pevans@rockymountainair.com.

John Segura, PE

About the Author

John Segura is a licensed Professional Engineer and a well-rounded executive in the industrial gas business. 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 caused his eventual leadership of the marketing efforts of technology worldwide industrial gas suppliers. He now consults to the industry on the business specializing in operations, applications and marketing.