Emissions vary across industries. What does not vary across industries is the need for cleaner air. Different emissions require different air pollution control solutions. Baghouses can handle high quantities of dust, but cannot handle extremely moist or sticky dust, tars, or oily substances. Conversely, wet electrostatic precipitators (WESPs) cannot handle high quantities of dust but are an optimal solution for extremely moist or sticky dust, tars, and oily emissions.
WESPs are a highly efficient solution for many complex pollutants. Here, we discuss the science behind WESPs and their many applications. Keep reading to learn more about the science behind WESPs.
What Is a WESP?
An electrostatic precipitator removes particles from a gas stream by using electrical energy to charge particles, which are then attracted to a collection surface. The collected particles are either removed from the collection surface as dry material (dry ESP) or with water (wet ESP or WESP). There are four steps to the precipitation process: ionization, particle charging, particle collection, and particle removal.
WESPs are available in different configurations and are a discrete and efficient part of operations. WESP collection tubes can be utilized in up or downflow operation. The various designs have different advantages depending on size and operational needs. Round tubes are preferred to the hex tube design because of their superior performance and longevity.
A WESP is an air pollution control device that utilizes electricity and water to capture pollutants. It is highly efficient at removing the following from industrial gas streams: ultra-fine particles, aerosols, mists, organic particulate matter, and sticky particulate matter. WESPs can be the preferred solution when the gas stream is wet or there is a fire risk.
How a WESP Works
A WESP uses electrostatic forces to remove particulate matter emissions in exhaust gas streams. Unlike a baghouse, a WESP utilizes stainless steel tubes. A system will utilize a large number of tubes, in some instances 200 or so. The tubes are grounded, and in the middle of each tube is an electrode connected to a power source.
Inside the tube is where all the action occurs. The particles and droplets in the gas stream flow through the tube between the discharge electrodes (middle) and collection electrodes (collection surface/tube wall). The power source changes the frequency and adds volts to the electrode, so when the gas goes through the tube, the electric field charges the particles. The electric field is so strong that it is actually visible inside the tube as corona blue plasma.
The particulates get electrically charged, and because of the charge, they start moving to the collection surface (tube wall) where they are deposited. All of the particulates will build up on the tube wall and are then flushed down to be processed as part of the waste stream.
WESP Benefits
WESPs offer a number of benefits as an air pollution control technology. Notably, WESPs have no barriers to gas flow, operate with low pressure drop, and are designed for 90% to 97% removal efficiency. ANDRITZ provides systems offering 97% removal efficiency in parts per billion (not parts per million). Operationally, WESPs are easily integrated into existing systems.
WESPs can be a preferred option for a number of industries and needs. This includes saturated gas streams, sticky or difficult-to-handle dust, combustible dusts, or when there is a large amount of sub-micron capture required. The technology is a superior option for sub-micron capture when compared with a venturi scrubber or baghouse, as it captures particulates that would pass through the other systems.
When included as part of a scrubbing system, WESPs do not add to the water demand because water used by the WESP can be reused in the upstream quench process. Additionally, the demand for electric power in a WESP is small compared to other technologies, relieving concerns regarding power consumption and utilization. This is because WESPs use electrostatic forces. Furthermore, WESPs are passive devices without moving parts. These features make WESPs an ideal technology for controlling fine particle emissions.
WESP Applications
WESP technology can be utilized in a broad range of applications. The effectiveness of the systems in the U.S. and around the globe has been demonstrated for decades. Notable applications include the following:
- Plywood veneer dryers
- Biomass-fired boilers
- Fiberglass manufacturing
- Semiconductor fabrication plants
- Industrial fryers and dryers used in potato processing
Geoenergy® E-Tube® WESP
El Geoenergy® E-Tube® WESP system is a leading air pollution control device. For more than 40 years, industries have trusted Geoenergy to provide best-in-class performance.
El Geoenergy® E-Tube® WESP has a number of key features. Our round collecting tubes are designed to maximize electric field strength for optimal performance. The external tube cooling system reduces water consumption, improving overall efficiency. The unique shape of our Star II™ electrode improves overall efficiency and reduces both the footprint and cost of the system. The bold design of our Sphere™ adjustment hardware simplifies maintenance and electrode adjustment.
Contact ANDRITZ
ANDRITZ is your trusted partner for WESP systems and particulate matter collection. Our clean air technology delivers superior results for a variety of industrial applications.
Now is the time for smarter solutions. Contact ANDRITZ today to learn more.
