Downstream of a WESP, the 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.
The Engineered Wood & Pellets industry make products such as OSB board, paneling, treated lumber, and wood pellets (burned for energy production). These processes, like all manufacturing processes, use water. All the water that these facilities use is reused back into their process. That's right, the wood industry is very water conscious. These operations utilize valuable equipment like Wet Electrostatic Precipitators (WESP) and Regenerative Thermal Oxidizers (RTO). These units require regular maintenance as excess tars and saps found in the water can gum (sticky seal, like resin) the equipment. It cost as much as $1 million (yes, one million) to replace the RTO media when it becomes fouled. When it is replaced, the plant has to be shut down. That $1 million doesn't include the costs associated with the down time, added labor, or waste disposal... So, the treatment of the water they reuse is a key cost saving factor for these operations, not to mention performance insurance for their equipment. Remember, if the manufacturers are saving, the consumer is too. ProChem, Inc. designs chemical treatment programs that protect the WESPs and RTOs so that the water is usable and the equipment lasts. Here is a case study from a ProChem customer, a Bio pellet manufacturer in Georgia: The customer was incurring high costs associated with maintaining their process equipment. Specifically, they were:
The cause was the poor quality of their water, which contained excess tars, saps, tannins, and lignins. To resolve this issue, ProChem, installed a new water treatment system that utilized a custom tailored chemical treatment program, CleanWESPTM, to remove TSS, tars, and saps while reducing the TDS in the recycle tank water. This provided the customer with cleaner recycle water and clean WESP flush water. ProChem also provided a treatment program for the shutdown water so that the facility could treat and discharge within discharge permit limits (rather than storing it on site).
It has now been over 9 years since the system was implemented, and the customer has not had to replace the RTO media at all in that time. Additionally. their costs and manpower required for routine planned maintenance has been reduced by 80%. Furthermore, solid waste generation has been reduced by 60% - 70% with filter case now at 40% - 50% moisture (as compared to the previous 80%+).
The EPA recently rolled out the final, updated ELGs for the power generation industry. ProChem and EES have partnered to provide a solution that not only meets these limits but exceeds them. The KLeeNwater solution features ProChem’s I-PRO™ technology and a recommended chemical pretreatment program. Here is the data.
|Analyte||Unit||Daily Maximum Limitation||30 Day Average Limitation||KLeeNwater Process|
|Total Suspended Solids||mg/l||100||30||0|
|Boron||mg/l||No current limit||No current limit||0.5|
|Bromides||mg/l||No current limit||No current limit||<0.1|
|Chlories||mg/l||No current limit||No current limit||7|
|Total Dissolved Solids||mg/l||No current limit||No current limit||10|
|Sulfates||mg/l||No current limit||No current limit||2|
KLeeNwater can be integrated with existing wastewater treatment equipment and has a footprint that is a fraction of the size of traditional selenium removal systems. ELG compliance is possible with the KLeeNwater solution.