Packed Tower Scrubbers are vital pollution control devices that are primarily used to absorb gases from a wide variety of processes before the gas stream is released into the environment. Many industrial and municipal businesses are regulated using operating permits issued by a regulating body and require certain criteria are met. However, packed tower scrubbers can also be engineered to recover product and increase plant recovery in certain applications. The application of packed tower scrubbers is common in industry because this style of scrubber is highly versatile and can be engineered to address a wide range of pollutants.
Packed Tower Scrubbers use a form of “wet scrubbing” in which a chemical solution, often referred to as liquor, is distributed throughout the tower to absorb specific gas or gases from the gaseous phase into the liquid phase. As the liquor is sprayed inside the tower using spray bars, the liquor falls onto a material called tower packing. The packing provides the interface to allow gas/liquid contact. To improve the efficiency of pollutant removal, different types of packing can be used inside of the tower to increase the contact area in which the liquor meets the gas. The contact area allows for both heat and mass transfer to be performed at a greater efficiency than if only sprays were used. Scrubber packing can vary in the material of construction, pressure drop, size, and shape depending on the process application and design requirements of the scrubber.
The term “Packed Tower Scrubber” usually is in reference to an entire system, which will typically include:
- Controls and instrumentation
- Industrial blower
- Recirculation pump
- Scrubber packing
- Tower (vessel)
- Mist eliminators
- The exhaust stack
The tower can be configured in either the horizontal or vertical orientation. Packed Tower Scrubbers are also called packed-bed scrubbers and packed-column scrubbers. The layer of packing material is colloquially called a “bed” and the towers are often cylindrical so resemble a column shape. Packed Tower Scrubbers are designed to entrain certain chemicals at specified parameters that include but is not limited to:
- Volumetric flows
- Gas concentrations
- Temperature range
This unit operation is highly reliable and easily adapted to many different applications. Some examples of pollutants that can be effectively removed are:
- Inorganic gases
- Organic gases
- Particulate matter (PM)
While packed tower scrubbers have low maintenance requirements, the scrubber packing media does tend to be susceptible to a phenomenon referred to as channeling. Typically, the scrubbing liquor is evenly distributed across the diameter of the tower and percolates through the scrubber packing uniformly. Channeling is when sections of the packing become plugged off, forcing the gas to go through different “channels” inside of the packed bed. When this occurs, it creates higher gas velocities in the channels, potentially exceeding the capabilities of the tower packing as well as the installed mist eliminators. This could lead to an increased quantity of pollutants that are released from the system. There are several factors that can create channeling; however, some common ones are plugged spray nozzles, change in makeup water chemistry, precipitation from solids, and flooding of the scrubber packing due to insufficient drainage.
To explore if Kimre’s KON-TANE® Scrubber and Tower packing can help satisfy your scrubber needs, visit our website.