Baghouse & DeNOx Glossary: Filter Bag, SCR Terms

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Glossary

Terms used in dust collection, DeNOx and flue gas treatment, each defined in one line.

Filter Bags and Media

Filter Bag: Replaceable filter element in a baghouse that captures dust from flue gas.
Filter Media: Filtering material of a filter bag: a base fabric, often with a surface layer such as a membrane.
Base Fabric (Substrate): Fiber layer forming the bag body, chosen to suit gas temperature, acids and moisture.
Needle Felt (Nonwoven): Nonwoven felt made by entangling fibers with needles, used as pulse-jet bag base fabric.
Woven Fabric: Fabric of interlaced yarns, used for filter bags in shaker and reverse-air baghouses.
Scrim: Open woven fabric inside a needle felt that adds strength and dimensional stability.
PTFE (Polytetrafluoroethylene): Fluoropolymer filter material for 232–260°C continuous service, resistant to acids and alkalis.
PPS (Polyphenylene Sulfide): Filter material for 190°C continuous service with strong acid resistance, but weak to O₂ and NO₂.
Polyimide (P84): Polyimide filter material for 216–260°C continuous service in hot, low-pH gas.
Meta Aramid (Nomex®): Filter material for 190–200°C continuous service with hot, abrasive dust.
ePTFE Membrane: Microporous film of stretched PTFE that captures dust at the media surface.
Node–Fibril Structure: Network of nodes and fine fibrils formed when PTFE is stretched, creating its fine pores.
Lamination: Bonding an ePTFE membrane to the base fabric; air permeability and bond strength are key.
Pore Size and Distribution: Size and uniformity of membrane pores, which govern capture efficiency and resistance.
Air Permeability: Airflow through filter media at a set pressure difference; lower values mean higher ΔP.
Hydrolysis: Chemical breakdown of fibers by hot moisture, to which polyester (PET) is especially prone.

Dust Collection and Filtration

Baghouse (Bag Filter): Dry dust collector that removes dust by passing flue gas through filter bags.
Electrostatic Precipitator (ESP): Dust collector that charges particles with high voltage and collects them on plates.
E.BF (ESP + Bag Filter Hybrid): Hybrid collector where an ESP removes most dust first and a baghouse captures the rest.
Depth Filtration: Filtration in which dust enters the felt, so residual ΔP rises over time.
Surface Filtration: Filtration at the ePTFE membrane surface that keeps dust out of the felt.
Dust Cake: Dust layer on the filter surface that aids capture but raises ΔP as it thickens.
Filter Cleaning: Removing dust built up on the filter surface to bring differential pressure back down.
Pulse-Jet Cleaning: Cleaning by a short burst of compressed air into the bag to release dust from its outside.
Reverse-Air Cleaning: Cleaning by isolating a compartment and passing gas in reverse to release dust.
On-Line / Off-Line Cleaning: On-line cleaning runs while gas flows; off-line cleaning isolates the compartment first.
Cage: Metal support inside each pulse-jet filter bag that keeps the bag from collapsing.
Tubesheet: Plate from which filter bags hang, separating the dirty-gas and clean-gas sides.
Diaphragm Valve: Valve that opens and closes instantly to release compressed air in pulse-jet cleaning.
Blowpipe: Pipe that delivers compressed air to one row of filter bags in pulse-jet cleaning.
Hopper: Funnel-shaped section below the baghouse that collects and discharges removed dust.
Differential Pressure (ΔP): Pressure difference across the filter bags, an operating indicator that rises as dust builds up.
Residual Pressure Drop: ΔP remaining right after cleaning, used to judge filter condition and replacement timing.
Blinding: Wet or very fine dust plugging the filter so that ΔP stays high even after cleaning.
Air-to-Cloth Ratio (A/C Ratio): Actual gas flow divided by filter cloth area, expressed in m/min.
Net / Gross Cloth Area: Gross is the area of all bags; net excludes compartments off line for cleaning or service.
Dust Resistivity: How strongly dust resists electric current, a major factor in ESP efficiency.

Catalytic Filters and DeNOx

Catalytic Filter Bag: Catalyst-loaded filter bag that captures dust while decomposing NOx and other harmful gases.
CataFill™: Micro-one's catalytic filter bag: an ePTFE membrane laminated to catalyst-loaded PTFE felt.
Catalyst Loading: Process of coating and bonding catalyst components evenly onto filter media fibers.
Catalyst Poisoning: Loss of catalyst activity as flue gas components cover or react with the catalyst surface.
DeNOx: Treatment that reduces NOx in flue gas by converting it to nitrogen and water.
Nitrogen Oxides (NOx): Collective term for nitric oxide (NO) and nitrogen dioxide (NO₂) formed during combustion.
Reducing Agent (Ammonia, Urea): Substance such as ammonia or urea solution injected to convert NOx to nitrogen.
Normalized Stoichiometric Ratio (NSR): Reagent actually injected divided by the theoretical amount; 1.0 is exactly stoichiometric.
Ammonia Slip: Ammonia that does not react in DeNOx and leaves the system with the flue gas.
Selective Catalytic Reduction (SCR): DeNOx system that passes reagent-dosed flue gas through a catalyst to convert NOx to N₂ and water.
Selective Non-Catalytic Reduction (SNCR): DeNOx system that injects reagent into the hot furnace zone to reduce NOx without a catalyst.
Ozone Oxidation: NOx treatment that oxidizes NO with ozone so the higher oxides can be absorbed in a wet scrubber.
Hydrogen Cyanide (HCN): Toxic gas that can occur in refining and chemical flue gas; catalytic filter bags can decompose it.

Acid Gases and Flue Gas

Semi-Dry Reactor (SDR): System that sprays lime slurry to neutralize acid gases while flue gas heat evaporates the water.
Dry Reactor (DR): System that injects lime and activated carbon powder to neutralize acid gases and adsorb pollutants.
Wet Scrubber: Wet system that contacts flue gas with a scrubbing liquid to absorb acid gases and dust.
Dioxins: Collective term for chlorinated dioxin and furan compounds (PCDD/F) that can form in combustion.
Acid Dew Point: Temperature at which acidic flue gas components start to condense, above the water dew point.
Oxygen Correction: Calculation converting a measured emission concentration to a reference oxygen level.
Normal and Standard Conditions (Nm³): Reference temperature and pressure for comparing gas volumes; the temperature differs by standard.
Continuous Emission Monitoring (CEMS / TMS): Korean remote monitoring system that measures stack emissions in real time and reports them.

Systems and Certifications

ESP Retrofit (Retrofit EP): Upgrade of an existing ESP's power supply, electrodes and gas distribution to raise efficiency.
Computational Fluid Dynamics (CFD): Simulation of gas flow, temperature and particle movement to preview conditions inside equipment.
Solid Refuse Fuel (SRF): Solid fuel made by processing combustible waste such as waste plastics and waste wood.
HEPA / ULPA: High-efficiency air filter classes that capture very fine particles, used in cleanrooms.
Korea New Environmental Technology (NET): Korean certification of new environmental technology performance; Micro-one holds NET No. 631.
Green Technology Certification (Korea): Korean government certification for green technologies; Micro-one holds GT-26-02540.

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Glossary

Filter Bags and Media

Dust Collection and Filtration

Catalytic Filters and DeNOx

Acid Gases and Flue Gas

Systems and Certifications