Fouling on turbine blades can have a significant negative effect on their performance and may, if left unchecked, lead to turbine failure. Turbine cleaning is thus a critical part of any turbine operator's maintenance regimen. One of the most popular methods of turbine cleaning is the pressurized carbon dioxide (CO2) jet process. This process involves projecting a high pressure stream of frozen CO2 pellets at the fouled turbine parts. The pellets remove the fouling on the turbine blades without damaging them and evaporate into CO2 gas, thereby leaving no additional mess.
Turbines are finely engineered pieces of machinery which rely on a high degree of balance integrity to operate at optimal efficiency. Unfortunately, the average turbine operating environment is fairly aggressive and laden with contaminants which quickly form deposits of scale or carbon on the blades in the various turbine stages. These deposits, or fouling, can increase to the point where they eventually cause a state of imbalance in the turbine rotor. This leads to a gradual decrease in rotational speeds, and overall efficiency of the turbine and can, if not rectified, lead to rotor damage. These facts make the regular removal of fouling buildups an essential point on any turbine maintenance schedule.
The average industrial or aviation turbine has several stages consisting of thousands of individual turbine blades. In some cases,the performance sapping deposits on these blades may be removed by hand with solvents. This, however, is an extremely time consuming process, and other turbine cleaning methods such as CO2 blasting are far more popular. The CO2 turbine cleaning process involves blasting the blade surfaces with a high pressure jet of frozen CO2 pellets. Commonly known as dry ice, the frozen CO2 is softer than sand or glass beads and does not damage the sensitive blades or alter their geometry but is hard enough to wear away stubborn fouling.
The CO2 pellets are typically projected by a stream of compressed air from a handheld lance, thereby making the process flexible enough to get into all the small spaces on the turbine. The CO2 is also nontoxic and poses no danger to the process operator or the environment. An additional benefit of this type of turbine cleaning is the lack of mess left after cleaning. The frozen pellets quickly heat up during the process and evaporate into harmless carbon dioxide gas, thus leaving the work area clean and free of water and debris.