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3 Common Reasons to Use Wet Scrubbers

Posted on May 26, 2020
3 minute read

When it comes to air quality, it’s important to choose the best air pollution collection system for your specific application. Choosing the right system can mean the difference between a safe, productive work environment, and a plant shutdown.

Wet scrubbers, also known as wet dust collectors, are becoming increasingly popular in the industrial market due to their unique method of collection. Rather than filtering out contaminants with the filter media of a dry dust collector, wet scrubbers use a scrubbing liquid to remove gases, vapors, dust and other pollutants through the impingement process. With this liquid, the efficiency of a wet scrubber can be controlled by the size of your water droplets. Smaller droplets lead to higher efficiencies, allowing certain wet scrubbing systems like Sly’s Venturi/Impinjet® combination scrubber to remove pollutants from stack emissions with a 99.999% efficiency rating.

By using a wet scrubber, you have the unique opportunity to remove both particulate and gases/vapors from an airstream with one system. This makes wet scrubbers the perfect solution for a wide variety of industries, including pharmaceuticals, food production, plastics, and machining. No matter the application, the top three conditions for using a wet scrubber are:

  • Wet or sticky particulate
  • Humid air
  • Combustible dust

Wet or Sticky Particulate

Particulate that’s wet or especially sticky/gooey can clog a standard baghouse, leading to a host of problems. With the mechanisms of wet scrubbing, dealing with wet or sticky particulate isn’t an issue. You’re already creating a process that’s meant to mix with water, so you don’t have to worry about a hydrophobic collection system.

Humid Air

Problems with humid air can happen independently from the wet or sticky particulate issue. A great example is sand drying applications. While these processes mostly deal with dry particulate, humid air can cause condensation to form within a typical baghouse. Sand and similar particulate are also very abrasive, which can cause excessive wear on dust collectors and filter bags. All of this means more maintenance, replacement parts, and system downtime if you use a baghouse. However, wet air scrubbers were made for these types of applications, allowing your business to keep on running smoothly.

Combustible Dust

Dust explosions are a significant issue when it comes to dust collection. While they can happen for a variety of reasons, every explosion requires five key elements:

  • Combustible fuel
  • Adequate fuel dispersion
  • An ignition source (heat, friction, static electricity, etc.)
  • Free oxygen
  • Confined fuel sources

When it comes to the fuel for an explosion, many dusts can be combustible, igniting under certain conditions. According to the NFPA, a combustible dust is any solid material that’s composed of distinct particles or fragments smaller than 500 microns that can be a fire hazard when suspended in air or any other oxidizing medium over a range of concentrations. These can include anything from agricultural products like powdered milk and grain flours, to metallic and chemical dusts from aluminum and sulfuric acid. Dispersing these dusts in confined quarters – like a baghouse – can make them extremely explosive when in the presence of an ignition source. Even just a single spark can lead to a dust explosion in these conditions. 

Wet dust scrubbers effectively eliminate the risk of a dust explosion within the collector by mitigating and removing many of the factors required for an explosion. Using a scrubbing liquid, wet scrubbers can reduce heat sources, stop clouds of dust from forming, and eliminate dust dispersion by aggregating dust particles within water droplets. Of course, dust explosions can still occur downstream, and especially upstream, from the wet scrubber, so you need to properly handle combustible dust at every stage of the collection process, not just within the wet scrubber itself.

Selecting the Right Wet Scrubber

When it comes to wet scrubbers, there are several types that you can choose from, each designed for different applications. Sly specializes in each of the following:

Impinjet® Wet Scrubbers

Impinjet® wet scrubbers are used to collect a variety of particulates, vapors, and gases. Highly resistant to fouling, these scrubbers offer lower levels of water consumption and high collection efficiencies of 99% for particles 5 microns or larger.

Venturi Scrubbers

Designed to collect fine particles and mists, Venturi scrubbers use the differential between high-velocity gases and free-flowing water to create ultra-fine droplets for entrapping contaminants and holding them in suspension. Capable of removing the smallest of particles, Venturis can be coupled with Impinjet® scrubbers for even higher collection efficiencies.

Eductor Wet Scrubbers

Eductor scrubbers can remove both soluble particles and gases by inducing a gas flow focused into a Venturi throat using high-pressure liquid. They can also be used for direct-contact condensation. By eliminating the need to have a separate blower or exhaust fan to move the pollutant-laden airstream to the filtration device, Eductor scrubbers can maintain high collection efficiencies.

Choosing the right type of wet scrubber to fit your unique needs will be crucial to getting the most out of your system, and keeping your business running at its best.

The Sly Advantage

With over 150 years of experience in controlling dust, the experts at Sly can help you find the right wet scrubber or baghouse for your unique application. If you want a knowledgeable team behind your air quality control, contact us or request a quote today.

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Tags: wet scrubber, venturi, impingement

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