Downstream of a wet electrostatic precipitator (WESP), the regenerative thermal oxidizer (RTO) can receive a multitude of residual particles from the air, including those found in water vapor. These particles are left behind in the media and can plug it up, causing it to become dysfunctional. Hydro blasting and/or caustic cleaning may clean the media successfully, but it is only effective for a few cleaning cycles--and it's expensive. The other repair option is to replace the media, which can cost millions of dollars between the materials, labor, and plant downtime.
To prevent RTO media fouling, you have to know what's going in to the RTO; that is, you must know the inputs. In this way, you can predict what may linger behind on the media that could foul it and then implement a method of removal prior to the RTO. RTO inputs include both coarse and fine particles. Coarse particles (those over 5 microns) may be dust or liquid droplets. Likewise, fine particles (those less than 1 micron) can be liquid or solid, depending on their makeup. Fine particles are typically formed when vapor cools and condenses into a particle and can include oils, resins, and iron as as a solid. Liquid fine particles such as tars and lignins will be left behind deep within the RTO media as the water evaporates. Some fine particles such as sodium and potassium oxides and others, like chlorides, can cause more damage than plugging. Because they are chemically reactive, they will actually react with the makeup of the media itself at high temperatures. This reaction can cause the media to become brittle. One way to save on costly repairs and replacement is to prevent the inputs from entering the RTO in the first place. Removing or reducing water contaminants such as tars, lignins, sodium, potassium, and chlorides from the water fed to the WESP prevents any of those liquid fine particles from entering the RTO. This can extend the life of the RTO media life indefinitely.
CleanWESPTM is a chemical treatment program designed to remove damaging contaminants from recycle tank water in order to protect valuable equipment and save time. ProChem, Inc. performs a treatability study on the water from each customer site to determine the appropriate treatment program for that situation. The goal of CleanWESP is to protect valuable equipment, saving the customer down time and maintenance costs.
