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If you are a plant manager, a process engineer, or a purchasing or Environmental Health and Safety (EHS) professional who works in industrial manufacturing or the wastewater treatment industry, then you may be seeking a solution to remove harmful pollutants and odors from your process exhaust streams before they are released into the atmosphere and contaminate the outside air. One technology worth strong consideration is the industrial scrubber.
Industrial scrubbers are pollution filtration systems that utilize solids (in “dry scrubbers”), or water or other liquids (in “wet scrubbers”) to remove gas pollutants and odors from exhaust streams. In general, the main advantages of industrial scrubbers to clean gas exhaust streams include:
Dry Vs. Wet Scrubbers
Industrial scrubbers are categorized as either “dry” or “wet”. Dry scrubbers generally cannot achieve the same level of pollutant removal as wet scrubbers, but they are well-suited for applications in facilities that lack the infrastructure to properly handle produced wastewater.
Dry scrubbers remove pollutants from exhaust gases without the use of liquids. Instead, they utilize a dry reaction material known as “sorbent”, such as alkaline slurry, and they are primarily implemented for removal of acid from gas by moving the gas through the sorbent “dust” to maximize binding.
In contrast to dry scrubbers, wet scrubbers move contaminated gas through a liquid that is designed to remove pollutants. Wet scrubbers constitute a versatile and cost-effective pollution control technology that can eliminate more than 99% of airborne particulate matter.
How Wet Scrubbers Work
Water is the most common solvent used to remove inorganic contaminants. In the most basic form of wet scrubbers, water is encapsulated in a metal or composite container, contaminated gas is moved through the water, the water then absorbs the contaminates, and clean gas exits the scrubber.
Aside from water, other liquids can be used as absorbing solutions to effectively remove varied contaminates. Manipulating the chemical composition of the absorbing solutions changes the overall charge, which can be highly positively charged, negatively charged, or non-charged. Because pollutants differ in their charge, wet scrubbers are packed with the liquid that will bind most effectively to remove the contaminate from the gas. Caustic solution (sodium hydroxide, NaOH) is the most common scrubbing liquid used for acid-gas control (e.g., HCl, SO2, or both), though sodium carbonate (Na2CO3) and calcium hydroxide (slaked lime, Ca[OH]2) are also used.
Wet Scrubbing of Particulate Matter
Wet scrubbers can remove particulate matter by capturing them in liquid droplets. The droplets are then collected, with the liquid dissolving or absorbing the pollutant gases. Any droplets that are in the scrubber inlet gas must be separated from the outlet gas stream using a mist eliminator. Also, the resultant scrubbing liquid must be treated prior to any ultimate discharge or being reused in the plant.
A wet scrubber’s ability to collect particulate matter is often directly proportional to the power input into the scrubber. Additionally, a properly designed and operated mist eliminator is important to achieve high removal efficiencies.
If the gas stream contains both particulate matter and gases, wet scrubbers are generally the only single air pollution control device that can remove both pollutants.
Packed-Bed Wet Scrubbers
Wet scrubbers that remove gaseous pollutants are referred to as absorbers. Good gas-to-liquid contact is essential to obtain high removal efficiencies in absorbers. Various wet-scrubber designs are used to remove gaseous pollutants, with one of the most popular sub-categories of wet scrubber known as Packed-Bed, Packed-Tower, or “acid gas” (when they are used to control inorganic gases).
Although they can also collect solid particulate matter, Packed-Bed scrubbers are generally used more for the treatment of gas. Packed-bed scrubbers are typically used in the chemical, aluminum, coke and ferroalloy, food and agriculture, and chromium electroplating industries, in acid plants, fertilizer plants, steel mills, and asphalt plants.
If you are a plant manager, a process engineer, or a purchasing or Environmental Health and Safety (EHS) professional who works in industrial manufacturing or the wastewater treatment industry, then you may be seeking a solution to remove harmful pollutants and odors from your process exhaust streams before they are released into the atmosphere and contaminate the outside air. One technology worth strong consideration is the industrial scrubber.
Industrial scrubbers are pollution filtration systems that utilize solids (in “dry scrubbers”), or water or other liquids (in “wet scrubbers”) to remove gas pollutants and odors from exhaust streams. In general, the main advantages of industrial scrubbers to clean gas exhaust streams include:
Dry Vs. Wet Scrubbers
Industrial scrubbers are categorized as either “dry” or “wet”. Dry scrubbers generally cannot achieve the same level of pollutant removal as wet scrubbers, but they are well-suited for applications in facilities that lack the infrastructure to properly handle produced wastewater.
Dry scrubbers remove pollutants from exhaust gases without the use of liquids. Instead, they utilize a dry reaction material known as “sorbent”, such as alkaline slurry, and they are primarily implemented for removal of acid from gas by moving the gas through the sorbent “dust” to maximize binding.
In contrast to dry scrubbers, wet scrubbers move contaminated gas through a liquid that is designed to remove pollutants. Wet scrubbers constitute a versatile and cost-effective pollution control technology that can eliminate more than 99% of airborne particulate matter.
How Wet Scrubbers Work
Water is the most common solvent used to remove inorganic contaminants. In the most basic form of wet scrubbers, water is encapsulated in a metal or composite container, contaminated gas is moved through the water, the water then absorbs the contaminates, and clean gas exits the scrubber.
Aside from water, other liquids can be used as absorbing solutions to effectively remove varied contaminates. Manipulating the chemical composition of the absorbing solutions changes the overall charge, which can be highly positively charged, negatively charged, or non-charged. Because pollutants differ in their charge, wet scrubbers are packed with the liquid that will bind most effectively to remove the contaminate from the gas. Caustic solution (sodium hydroxide, NaOH) is the most common scrubbing liquid used for acid-gas control (e.g., HCl, SO2, or both), though sodium carbonate (Na2CO3) and calcium hydroxide (slaked lime, Ca[OH]2) are also used.
Wet Scrubbing of Particulate Matter
Wet scrubbers can remove particulate matter by capturing them in liquid droplets. The droplets are then collected, with the liquid dissolving or absorbing the pollutant gases. Any droplets that are in the scrubber inlet gas must be separated from the outlet gas stream using a mist eliminator. Also, the resultant scrubbing liquid must be treated prior to any ultimate discharge or being reused in the plant.
A wet scrubber’s ability to collect particulate matter is often directly proportional to the power input into the scrubber. Additionally, a properly designed and operated mist eliminator is important to achieve high removal efficiencies.
If the gas stream contains both particulate matter and gases, wet scrubbers are generally the only single air pollution control device that can remove both pollutants.
Packed-Bed Wet Scrubbers
Wet scrubbers that remove gaseous pollutants are referred to as absorbers. Good gas-to-liquid contact is essential to obtain high removal efficiencies in absorbers. Various wet-scrubber designs are used to remove gaseous pollutants, with one of the most popular sub-categories of wet scrubber known as Packed-Bed, Packed-Tower, or “acid gas” (when they are used to control inorganic gases).
Although they can also collect solid particulate matter, Packed-Bed scrubbers are generally used more for the treatment of gas. Packed-bed scrubbers are typically used in the chemical, aluminum, coke and ferroalloy, food and agriculture, and chromium electroplating industries, in acid plants, fertilizer plants, steel mills, and asphalt plants.
