Carbon DIoxide, CO2, or Super-Gas?

AOC Mexico S.A. de C.V. is a trusted supplier of carbon dioxide to Mexico and surrounding areas.

The majority of people not involved the industrial gas industry recognize carbon dioxide, CO2, as the carbonation in soft drinks 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

In the early 1600’s, Jan Baptista von Helmont, a Finnish scientist, discovered CO2 as the gas that resulted from burning wood. In the mid 1700’s an English chemist named Joseph Priestly, discovered that the combination of water and CO2 being dispensed from a fermentation process generated sparkling water which altered the water’s taste and was the driving force behind the start of the soft drink industry.

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

Gas

CO2 is most often associated by those in the gas industry with the food and beverage industry for its use as a refrigerant or as a shielding gas in welding. CO2 also has other attributes that contribute to its uniqueness .

The most fitting example is when after making contact with water, CO2 forms carbonic acid. Although it is not a very powerful acid, it is an acid nonetheless and has the ability to modify the pH in some processes where the pH is a relevant system parameter. This is evident in some industries such as paper production, textiles, and water treatment processes. An additional benefit is that carbonic acid is not stored as an acid (such as sulfuric or hydrochloric acids). As mentioned, the CO2 needs water to create 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 approximately around 800 psig depending on the ambient temperature. The result is that any method using liquid CO2 should be under pressure. Those involved in the oil industry are aware can compensate for water in enhanced oil recovery (EOR) where the liquid is put in a blend with sand or sand like substance (proppant) and pumped down an oil well to recover oil that has been trapped between layers of rock. EOR is a wide-ranging term that can refer to several different processes but the most common is fracking. In fracking man made fissures are used to pump the propant into rocks that are rich in oil. As a result, the rock fractures and the trapped oil is released. 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’s not common knowledge that liquid CO2 is also used in the dry cleaning industry. In a certain high pressure washer, liquid CO2 is introduced with a stain remover. The clothes are then washed regularly employing turbulence to clean the wash. When the cycle is done, the dirt, grime and stain remover are separated from the liquid CO2. The liquid CO2 is then extracted to be recycled 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 attributes and is achieved through proper adjustment of temperature and pressure; this is known as the supercritical state. The supercritical state of CO2 can be generated in a uniquely 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 utilized applied in many different ways as a coolant. When liquid CO2 is transported through a high pressure line and passed through special nozzles, it instantly turns to CO2 snow and utilized to refrigerate and freeze food. Dry ice pellets can be used in plae of regular ice in bins that hold perishables for long road transportation.

Extremely small pieces of dry ice are (about the size of a grain of rice) applied as an abrasive to rid surfaces of coatings without damaging the surface itself by blasting 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 leading to a cleanup that is quite easy.

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

For more information on how you can be supplied with carbon dioxide in Mexico for any of your specialty gas operations, call AOC Mexico S.A. de C.V. at 818-647-7427 or at herrmann@aoc.com.mx.

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 been a leader to several teams of technicians and engineers through his work as an R&D manager for dominant gas companies. His work lead him to running the marketing efforts of technology worldwide industrial gas suppliers. He now consults to the industry on the business specializing in operations, applications and marketing.