Learn more about scrubbing applications and engineering

Packed Bed Fume Scrubbers and Wet Air Scrubbers

Monroe Air, Gas, and Fume Scrubbers

Packed Bed Scrubber features
Monroe Environmental is a single source solution for highly durable and efficient Packed Bed Scrubbers. A Packed Bed Scrubber is a wet type scrubber that removes soluble chemicals, fumes, and odors. Contaminated gas flows through a specially designed packing media that is wetted with recirculated liquid. The liquid solvent absorbs the gas pollutant by physical or chemical means. A blowdown from the tank with makeup water addition removes contaminant products before they precipitate.

Common contaminates removed by Monroe Packed Bed Fume Scrubbers include:

  • H2S
  • HCl
  • HCN
  • NH3
  • SOx - SO2, SO3, SO4
  • Cl2, F2
  • Formaldehyde
  • And many others
Monroe Environmental offers complete in-house fabrication and engineering services to provide high quality solutions at a low price. Monroe Environmental supports its customers with installation, start-up assistance, training, and field service. Each Packed Bed Scrubber is sized and designed for specific customer requirements. We will evaluate fume removal applications to determine the optimum design parameters for each installation. Monroe Environmental designs and builds complete scrubbing systems including multiple stages when required. We also design liquid clarification systems and other air cleaning devices, and can provide integrated complete systems.
Monroe Environmental Horizontal Scrubber Monroe Environmental Horizontal Scrubber

Wet Air Scrubber Features

  • Materials of construction include:
    • FRP
    • RTP (Reinforced Thermoset Plastic) and dual laminate
    • PVC and CPVC
    • Polypropylene and polyethylene
    • Stainless steel, mild steel, and FRP-lined mild steel
    • Nickel alloys
    • Titanium
  • Wide range of packing media including rings and saddles in various materials. Structured packing is also available.
  • Complete instrumentation and electrical controls are available for stand alone operation or connection with a facility's centralized control or monitoring systems.
  • Chemical treatment, including oxidation and neutralization, is available to increase absorption of gaseous pollutants. pH control available when applicable.
  • Corrosion resistant AMCA rated fan on the inlet or outlet side of the scrubber.
  • Corrosion resistant recirculating pumps for scrubber liquid recirculation.
  • Non-plugging spray nozzles for wetting packing in a wide range of corrosion resistant materials. Special liquid distributors may also be used.
  • Moisture eliminators with chevron, mist pad, or loose fill type designs.

Efficient Fume Scrubber Design

Monroe Environmental Packed Bed Scrubbers are custom designed to meet or exceed the specific removal efficiency required for each customer's application and process. Monroe can also provide a process simulation for difficult or unique scrubbing system applications. Monroe engineers will optimize the performance of each unit by thorough evaluation of relevant parameters.Monroe Environmental H2S Scrubber

Monroe will analyze:

  • Contaminant solubility
  • Vapor pressures
  • Wash liquid flow rate
  • Liquid to gas ratio
  • Packing chamber height, diameter, and volume
  • Packing media type and size
  • Chemical additives
  • pH control
  • Precipitation of reaction products
  • Multiple solution scrubbing
  • Required scrubbing stages
  • Pressure drop across packing
  • Materials of construction
  • Site requirements

Click here for Fume Scrubbing Applications/Engineering

Packed Tower Scrubber Flow DiagramVertical Packed Tower Fume Scrubber

This vertical assembly is a counter-flow design with contaminated gas flowing upwards and recirculating liquid spraying downward into the packing media. Gaseous contaminants are absorbed by the liquid due to solubility levels or by chemical reaction. Counter-flow scrubbers have a smaller footprint and can have higher removal efficiency than a Monroe Horizontal Packed Bed Scrubber.

The vertical counter-flow design typically provides the best scrubbing efficiency of vapors and is the most common design found in most industries. The Monroe Vertical Packed Tower Scrubber is normally not used when solid particulate is in the air stream. Air flow capacity for a single shop fabricated tower can be up to 75,000 CFM.



Horizontal Packed Bed Fume Scrubber

This is a cross-flow design with scrubbing liquid flowing vertically downwards while the gas passes horizontally through the packing section. A Monroe Horizontal Packed Bed Scrubber is used when limited headroom is an issue at a customer's facility or when low profile is desired for roof-top applications. Multiple stages can be easily provided in one housing with separate sumps and pumps if required.

The cross-flow design is less susceptible to fouling for airstreams that may contain solid particulate. Air flow capacity for a single shop fabricated tower can be up to 75,000 CFM.

Horizontal Scrubber Flow Diagram

Chromic Acid Fume Scrubber — Multiple Stage Design

Chromic Acid Scrubber Flow Diagram

Emissions from chrome plating and chromic acid anodizing operations produce hexavalent chrome mist that cannot be effectively removed in a conventional packed tower scrubber. A modified type of horizontal scrubbing unit using specialized mesh filter pads with periodic flushing is required to meet regulatory guidelines for this contaminant. PVC construction is typical.

Typical Chrome Applications

  • Anodizing Chrome
  • Chrome Etching
  • Chrome Manufacturing
  • Chrome Stripping
  • Hard Chrome Plating

Multi-Stage Air Scrubbing Systems

Multi-Stage Scrubbing System Layout

Multiple scrubbing stages with different scrubbing solutions can be achieved by providing multiple scrubbing towers in series. These configurations can provide the highest removal efficiencies as well as multiple gas constituent removal. The diagram above includes three towers in series that could be used for H2S and ammonia removal.

Additional components that may be necessary to properly treat a given air stream can include:

  • Quench towers
  • Venturi Scrubbers with clarification tanks (for particulate removal)
  • Carbon Adsorbers
  • Fiberglass filters
  • And many others

Learn more about Monroe's capabilities with multi-stage scrubbing systems


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pdfPacked Bed Scrubber.pdf (845k)

pdfAir/Gas Cleaning & Odor Control.pdf (3.2Mb)

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