air cleaning devices ii
DESCRIPTION
LEVTRANSCRIPT
Air Cleaning Devices Industrial Ventilation PDC
Spring Carolinas Section Meeting
Asheville, NC
Jonathan F. Hale, MPA Air Systems Corporation
Dust Characteristics
Size
Shape
Bulk
Density
Abrasiveness Agglomerativeness
Fibrous
Hygroscopicity
Chemical
Composition Type
Filter Challenge
Particle Size,
Particle Shape,
Air-to-Media Ratio/Velocity,
Particle Concentration Grains/DSCF,
Hygroscopicity,
Abrasiveness,
Ease of Release,
Aglomeritiveness
Particle Size Chart
Fume
Mist
Clay
Smog
Virus
Carbon Black
Tobacco Smoke
Colloidal Silica Milled Flour
Coal Dust
Pollen
Fertilizer
Bacteria
Cement Dust
Human Hair
Mold Spores
Clouds/Fog
Lint
Beach Sand
Silt Fine Sand
Spray
Dust
(Log Scale)
Relative Size of
Typical Airborne
Particulates
Microns (µ) 0.001 0.01 0.1 1.0 10 100 1000
Technical
Definitions
Atmospheric
Conditions
Scanning Electron
Microscope
Optical
Microscope
Visible to
Naked Eye
Mist/Drizzle/Rain
Dust Cake
Bag filter with scrim Dust cake on Cartridge
Dust Shape
Dust generating process
Spherical, fibrous, or flaky
Abrasiveness
Tendency to rub or wear away the media or the collector
Detergents, Rice hulls, or steel shot
Maintain velocity <2,000 fpm
Agglomerativeness
Tendency to gather into a ball, mass, or cluster
Paper, cellulose, cotton
Special cartridge or bag
Controlled airstream conditions
Hygroscopicity
Readily taking up and retaining moisture
Acids, starches, or cement
Relates to releasability of dust cake
Settling Chambers
Centrifugal Cyclones
High Efficiency Cyclones
Multicyclones
Is BACT on PC boiler <100mmBTU/hr.
Hopper evacuation can give high efficiencies,
Many small cyclones with inlets and outlets grouped.
Air Stream Characteristics
Temp
Humidity
Chemistry
Condensables
Gaseous Contaminants
Fabric Dust Collectors
Cartridge Style Dust Collector
Advantages:
– higher efficiency on very small particles,
– Very compact,
– Large surface area,
– Ease of changeout- especially on toxics,
– Lower pressure drop
Reverse-air Cleaning Round Dust Collector
Built-in cyclone,
Only one discharge point up to 70,000 cfm,
No compressed air required.
Filter Medias
Polyester
Polypropylene
Acrylics
Ryton
Nomex
Micro-Fibers
P 84
PTFE
Fiberglass
Hybrids
Anti-static
Cellulose
PTFE Membranes
Microstructure
Small Pore Size
High Porosity
Bi-axial Structure
Chemically Inert
Hydrophobic
Renewable Coatings
Precoats
Continuous coatings
Continuous Coating
Protect the filter components
– Oils
– Condensables
– Acids
– Fires
Extend the filter life
Reduce emissions
React with contaminants
– Acids
– NOx
Broken Bag Detectors
Triboelectric and Tribokinetic Devices for the Detection of Particulate Emissions
Triboelectric?? Tribokinetic??
What’s the Difference??
Triboelectric Effect
Tribokinetic Effect
Regulatory Outlook
•EPA has published a Fabric Filter Bag Leak Detection Guidance document
•Guidance document mentions tribokinetic (AC-coupled) devices, but states
that there was insufficient data to include them in the guidance.
•The MACT standard for the secondary lead smelting industry references
triboelectric bag leak detection as an alternative to opacity monitoring.
•“Trade Show Talk” is that EPA is considering triboelectric devices, when
calibrated against a Method 5 stack test, for emissions monitoring.
Electrostatic Precipitation
ESP-Side View
Utility Precipitators
Dry Precipitator Issues
Bypass of pollutants around collection cells
Pollutant resistivity,
Material buildup on components/sparks jumping from corona wire to ground,
Improper or to infrequent cleaning.
Wet Electrostatic Precipitator
Good on sticky and gooey blue-haze particles.
Requires intrinsic wastewater treatment system
Bar-B-Que Smoke, Liberty, NC
Particulate- wood smoke
Particulate- sticky grease aerosols
Wet Absorption
Mass transfer process occurs through a phase boundary absorbing the molecule in the medium, then,
Utilize absorbent chemistry to neutralize or bind the offending pollutant,
Can be done sometimes with a simple spray chamber effectively,
Generally requires less than 5” pressure drop,
Generally uses 5-10 gpm per 1000 scfm.
Gaseous Wet Scrubber Issues
Temperature limitations of media, box, and fan,
Corrosion limitations of media, box and fan,
Solubility of final products or particulate,
Generally accepted principle:
Efficiency varies directly with the Energy input- Water energy (gpm/pressure) or air differential pressure.
Scrubber diagram
Acid Vapors, mists
Oil Mists,
Some Organics
Odors
No Particles!
Components for Scrubber System
Mist Eliminator/Scrubber Combo
Wet Fan-
Fan with spray,
Cyclonic wet precleaner,
Cyclonic demister.
High Energy Contactor
Saturated plume,
Venturi section,
Cyclonic demister,
10-100” pressure drop,
Ammonia Injection Grid
(AIG)
NH3 Supply Unit
NH3
from others
Accumulator Vaporizer NH3 Storage Tank
Ammonia
Flow Control
Unit
Mixing
Dilution Fan
Chamber
NH3
Injection
Control
Reactor
(Catalyst)
NOXNON 700
Typical Flow of SCR System
350MW
250MW 175MW
VOC Abatement
Very application specific,
Six major types of abatement technologies with much differences and advantages and disadvantages,
Remember to factor in ongoing operational costs!
Straight Thermal Oxidizer
Typically on :
halogenated hydrocarbons,
Higher BTU streams
Sticky-gooies or other particulate-laden hydrocarbons
Direct Thermal Oxidation
Recuperative Oxidizer
Recuperative Thermal Oxidizer
Regenerative Thermal Oxidation
98+% thermal oscillating heat recovery,
Heat recovery media inexpensive,
Can be made low NOx,
With Catalyst bed-RCO
RTO
VOC Concentrator
Used on higher volumes at low concentrations
Acts like carbon adsorption only uses thermally inert hydrophobic zeolites
Hydrophobic Zeolite Wheel
Adsorbs 99+% of most VOCs,
Structured “clay” molecular sieve,
Won’t burn like activated charcoal,
Biofiltration
Blue Haze Polluter-Asphalt Batcher
Dense Fiber-Bed Filter
Blue Haze Filter-Cut through
Notes:
1st quarter inch
Particulate on surface,
Droplets on trailing side.
Reactant Bed Media/DLA Use media that:
Reacts,
Absorbs,
Adsorbs,
Oxidizes,
Neutralizes
Free Air Pollution Controls!
Most states allow rapid amortization of APC systems-5 years or less,
Check for property tax ad velorem exemption.
Always Use the Proper Design
Please come attend!
•Free Barbeque!
•Free Ventilation Manual!
•Free Connie!