![]() In order to keep the reservoir solution from building up with these salts a small waste stream, called the blowdown, is removed from the scrubber in order to add fresh water and keep the specific gravity of the liquid in the reservoir low enough so the salts will not precipitate out of the solution. NaOH reacts with most acids to reduce them to a benign salt solution and water. ![]() The most common base solution used in Acid Scrubbers is Sodium Hydroxide (NaOH). When the pH drops below the pH set-point necessary to sufficiently treat the acid vapors the metering pump will activate adding additional base chemistry into the scrubber reservoir. The amount of base chemistry required is monitored by a pH probe located in the reservoir. This base chemistry is mixed as the circulation pump draws it up and into the spray headers and it sprays back down into the reservoir over the packing. In order to efficiently metalize the acid in the air stream a base solution is injected by a metering pump into the reservoir. This covers the basic flow of an Acid Scrubber, the following discusses the treatment process in more depth. Once the vapor passes through the mist eliminator it travels through the blower and out the stack into the atmosphere. This increased contact time is critical to ensure the vapor stream is sufficiently treated and cleaned.Īny water droplets left in the clean air stream after it has passed through the packing will be removed by a mist eliminator located at the top of the scrubber tower. The geometric design of the packing, combined with the depth of packing in the tower, greatly increase the surface area on which the solution and the acid fumes come in contact with each other. This solution streams down soaking the packing and allowing the vapor stream, which is flowing upwards (countercurrent to the stream of liquid), to contact the moisture on the packing. This solution is used to remove the acid from the vapor stream and the spray nozzles ensure full coverage of the vapor stream to prevent channeling or allowing untreated air to pass through the scrubber. The reservoir is filled with solution which is drawn out by a circulation pump and dispersed above the packing by an array of spray nozzles. The amount of packing, size / diameter of tower, water circulation rate, blowdown and static pressure are all calculated based on the facility’s ventilation requirements.Ī Wet Packed Bed Scrubber utilizes a tower, which contains the packing, and a reservoir located at its base. These scrubbers can be Vertical or Horizontal in orientation all depending on the facility’s needs and location of the unit. One of the most efficient, economical and low maintenance ways to scrub acid fumes is with a Wet “Packed Bed” Scrubber. Horizontal Scrubbers are designed so that the gas stream passes horizontally through a section of packed media, while liquid scrubbing solutions still passes down vertically. Horizontal packed bed scrubbers are often utilized when clients have a limitation on headroom or a low-profile design is needed. Vertical Scrubbers tend to have a higher effeciency rating than those of horizontal scrubbers while taking up a smaller footprint. The gas contaminants are adsorbed into the liquid. Vertical packed towers are designed with a counter current flow while the contamintated air stream flows upwards and recirculating liquid sprays downward through into the packing media. All scrubbers can be designed vertically or horizontally to accommodate facility floor space or height requirements. The now scrubbed vapors are blown into a stack and dispersed to the atmosphere.Ī wet scrubber is just one example of the many types of air pollution control technologies available. The chemical vapors then travel up through a mist eliminator to remove additional particulates and water droplets. This reagent is used to neutralize any hazardous fumes or any unwanted particles from the chemical vapor stream. This packed bed chamber is wetted with a chemical reagent (or water) via spray nozzles inside the tower. The chemical vapors are drawn into the bottom of the tower and pass up through a packed bed chamber. In a wet scrubber a fan or blower system is used to draw chemical vapors through ductwork and into the scrubber tower. The most common type of scrubber is a wet scrubber. Scrubbers can be designed in many different sizes, styles, and materials of construction based on your facility's chemical emissions. Scrubbers help to control all forms of vapor/gaseous air pollution emissions which are hazardous to the environment. A scrubber is used to "scrub" exhaust streams of unwanted solids, liquids, or gas particles before they are released into the atmosphere.
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