Gas Scrubber

Basics

• The industrial equivalent of an Air Purifier
• Can use one, or man steps/methods
• Typically used for filtration of chemicals, but often particles as well
• More dust focused units may be called Dust Collectors

Methods/Steps

Cyclonic Filtration

• Useful for removing particles such as Flue Ash
• Also used in dust evacuation systems in machine shops, and in vacuum cleaners
• Although not used for this in most industrial applications, the consumer vacuum cleaner company, Dyson, maketed a model with seccondary cyclones supposedly capable of getting near HEPA preformance
  • This was acheived via a small neck, so small that semi-flexible portions were needed to allow clog preventing vibration
  • Also there was a final HEPA filter, but this was supposedly more of a backup
• Most units in industry have only the "primary" cyclone for large to medium-small particles (essentiall no smaller than fine sawdust and large dust
• Cyclonic Vacuum Cleaners tend to also have a smaller seccondary cyclone (or muliple to increase flow), that is used for more fine particles

Electrostatic Precipitation

• Electrically Charges the air and/or particles, then uses a "negative" electrode to cause them to precipitate

Dry Catalysts

• This is used to change some chemical pollutants into either less harmful forms, or ordinary chemicals
• this is used on most moder cars
• More expensive, yet also more compact and simple

Settling Chamber

• Use space to allow particles to settle
• Most effective for in-line use is some sort of baffle chamber
• Mainly used for larger particles

Fluidized Bed

• Fluidized Bed Scrubbers
• Uses either catalysts or carbon/activated carbon to react with and/or absorb pollutants from gas streams
• Complex yet effective
• Mainly used for gasous chemical pollutants

Thermal Methods

• This uses mainly heating or cooling, and sometimes the addition of catalyts or other chemicals
• Regenerative Thermal Oxidizer

Wet Scrubbers

• Essentially using liquids to absorb and/or react with particles and gasses in the gas stream
• Water can work for many applications such as remooving hydrogen sulphide (it turns to sulphuric acid, this was a product of historical gasworks, although most modern sulphuric acid comes from the Claus Process )
• Other liquids have their own applications
• For designs of these see Gas-Liquid Contactor

OSE Layouts

Heat Exchange/Heating/Cooling

• Hot Flue Gas etc may require pre cooling
• Heat Exchanger
• Heatsink
• Waterblock

Dust/Particles Removal

1. Primany Cyclone
2. Seccondary Cyclone(s)
3. Electrostatic Precipitator
4. Failsafe Filterbag/HEPA/ULPA Filter etc

Chemical Pollutants

Concentrator Stage

• May not be needed in all applications
• Pressure Swing Absorbtion
• Fluidized Bed Concentrator

Filtration/Treatment Methods

• Regenerative Thermal Oxidizer
• or
• Wet Scrubber