Air Pollution control devices

Electrostatic Precipitators (ESPs)

particulate device that uses electrical forces to move the particles out of flowing gas stream and onto collector plates

Fabric filter

Baghouse

fabric filters

removes dust from a gas stream by passing the stream through POROUS FABRIC.

Electrostatic Precipitators

Preferably used for industries (for other exhaust gas particles), such as cement, pulp and paper, petrochemicals and steel

fabric filters

Very large-scale vacuum cleaner bags, used to collect particles from industrial exhaust air

Venturi Scrubber

introduction of LIQUID STREAMS to remove solid particles

Venturi Scrubber

allows gas laden with particulate matter through a short tube with flared ends and a CONSTRICTED MIDDLE

Drawback of venturi device

productioin of wastewater

Cyclones

the general principle of INERTIA SEPARATION is that particulate laden gas is forced to changed direction

Hopper

collects particulate matter

Cyclone

allows cleaner air through top of the chamber, flowing upward in a SPIRAL VORTEX, formed with a downward moving spiral

Cyclone

Not so efficient with smaller particles. thus, used with other particulate control devices

Settling Chamber

used the FORCE OF GRAVITY to remove solid particles

Settling Chamber

the gas streams enters a chamber where the velocity of gas is reduced. Large particles DROP OUT OF THE GAS and are collected in hoppers

Thermal Oxidizers

produce a region of high temperature in which pollutants are OXIDIZED

Three T's of design and operation of Thermal Oxidizers

Temperature, Time, Turbulence

Catalytic Reactors

Used extensively to Control NOx emissions arising from burning of fossil fuels in industrial processes

Catalytic Reactors

Performs thermal destruction functions like incinerators, but at lower temperatures and for selected waste gases only

Adsorption

When gas or vapor is brought contact with a solid, part of it is taken up by solid

Activated Carbon

universal standard for purification and removal of trace organic contaminants from liquid and vapor streams

Regenerative system

usually contains more than one carbon bed

Non-regenerative

have thinner beds of activated carbon

Absorption

process where gaseous pollutant is dissolved in a liquid

water

commonly used in absorbent bed

Wastewater

drawback generated by Venturi scrubber

Biofilter

filled with biological support medium

Biofilter

polluted airstream introduced in pore space between media, bringing contact with attached microorganisms

Condensation

process converting gas or vapor to liquid

Contact condenser

gas comes contact with cold liquid

Surface condenser

gas contacts a cold surface in which cold liquid or gas circulated

Incineration

aka combustion

Inceneration

technique refers to rapid oxidation

Direct combustor

air and all combustible waste gases reacts AT THE BURNER

Thermal incinerators

waste gas pass OVER OR AROUND A BURNER FLAME into residence chamber

Catalytic Incinerators

very similar to incinerators

Catalytic Incinerators

after passing through flame area, gas pass over a catalyst bed