Case Study: Packed Tower Replacement
A fresh start is required for a tower air stripper at the end of its useful service life.
Challenge: Replace an aging packed tower air stripper with declining performance over time
Packed tower air strippers are the longest-serving air stripper technology used in water treatment. Tower air strippers are capable of high water flow rates and efficient VOC removal. Packed tower air strippers are a terrific option to treat large volumes of water when the process is relatively clean. Dirty water processes with heavy suspended & dissolved solids loading can cause issues with this type of air stripper. Packed towers utilize a hollow ball packing media, designed to maximize surface area for VOC transfer. This packing is prone to fouling in processes with elevated solids loading. Fouled air stripper packing can require changeout of the media pack or even require complete air stripper replacement.
H2K Technologies manufactures another style of air stripper designed to operate in processes with significant solids loading. Our DTA-series air stripper can improve treatment performance in processes impacted with dissolved iron, hardness, alkalinity, or TSS. They are much simpler to operate & maintain and typically allow longer run time with less downtime for cleaning. DTAs are an attractive option to replace packed tower strippers. H2K Technologies is experienced and highly knowledgeable with both types of systems and their capabilities. Our experience allows us to provide our customers a best-fit solution like this packaged tower replacement we built.
Solution: An H2K Technologies DTA-Series air stripper improves performance in a water treatment system with heavy solids loading.
Our customer approached us to replace an existing packed tower with declining performance due to fouling issues. The tower met treatment targets with clean packing, but it quickly accumulated solids which reduced airflow & treatment efficiency. This water treatment process called for a solution to reduce fouling and maintenance downtime. H2K Tech DTA-series air strippers don’t require any packing; they deliver air with coarse bubble diffusers located along the bottom of the unit. This air delivery method creates a well-mixed air/water interface for VOC stripping and transfer of contaminants to air.
H2K Technologies builds standalone treatment equipment and turnkey water treatment systems. This packaged DTA-6 air stripper skid we manufactured in 2024 highlights our system capabilities. This stainless steel air stripper was designed to provide ~99.5% stripping efficiency at 40 gpm for trichloroethene (TCE). A 1.5 HP centrifugal pump feeds the system influent with contaminated water and a 5 hp transfer pump discharges water from the integral clearwell. A high-pressure discharge pump was required to overcome pressure drop in downstream piping. A 7 ½ hp centrifugal blower supplied the process with 600 CFM to reach TCE effluent targets. All process pumps, blowers, and instruments are operated through a local control panel. This panel ensures everything operates together smoothly and safely.
It’s critical to note that air strippers don’t destroy VOCs, they transfer contaminants from liquid to air. Vapor phase carbon vessels are the most common method to capture organic compounds like trichloroethene from air stripper offgas. This project required a pair of 48” diameter vessels operated in series for TCE treatment. Vessels were mounted on a separate skid due to site space constraints and connected to the air stripper duct onsite. Residual liquid is commonly present in air stripper offgas and vapor-phase carbon performance can be negatively impacted by water. Moisture knockouts are a common solution to mitigate liquid loading in air.
An industrial moisture separator ensured liquid droplets get removed before impacting the carbon vessels in this system. Our proprietary moisture separator design uses 2-stage design to maximize liquid water removal from air. Air is introduced via a centrifugal inlet which drives water downward along the interior wall while air travels upwards. Airflow is distributed across a full-diameter demister to capture droplets that escape the centrifugal separation stage. This combination of centrifugal and demister action provides 99%+ removal of liquid droplets 10 microns or larger. Separated water is collected at the bottom of the tank and returned to the air stripper inlet with a 1 HP pump.
System controls are a key factor that makes H2K water treatment systems successful. Our in-house panel shop builds UL-508A & UL-698A listed control panels to operate our packaged treatment systems. Safety and process monitoring is a top priority with all systems we manufacture. Pressure, temperature, and level transmitters installed throughout the system relayed process info to the control panel for active monitoring and control. A touchscreen operator interface clearly communicates process status and alarms. This system was designed for quick system shutdown when alarms indicate the process is operating outside of design specification. The control panel for this system was integrated into a larger control structure shared by the rest of the industrial facility. This process used an Allen Bradley PLC to seamlessly fit with other plant equipment. We frequently package systems to interact with other equipment and can work with you for a best-fit option.
Results: This H2K Technologies’ air stripper packaged improved treatment efficiency and reduced service requirements
The most significant improvement this new system provided was to greatly reduce downtime for cleaning and maintenance. The packed tower required quarterly acid cleanings which required multiple days offline and significant chemical expense. This diffused air stripper requires occasional cleaning as well, but the process is much easier and less expensive. The DTA design facilitates service operations at comfortable working level to allow easy removal and cleaning of aerators. The improved cleaning procedure helps to maximize system uptime and reduce service costs. The physical layout of this air stripper skid is also much more efficient in its footprint. This system was installed inside on the factory floor, compared to the outdoor location of the packed tower. The old unit required operators to navigate manways at tall height which required additional safety equipment and training. Overall, this packaged air stripper skid surpasses the performance of the old unit in a more compact profile.
H2K Technologies takes pride in building turnkey systems that exceed customer expectations. Our dedicated team will examine every detail to ensure your system meets project demands. Every system we construct undergoes rigorous testing before shipping to site. Shop tests include leak testing, noise tests, and a run-through of programming logic. This process resolves potential issues before shipping and ensures smooth start-up on-site. Our friendly staff is always ready to support new requests and existing system questions by phone and email. Call us today and we’ll help make your next water treatment project successful.
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