Flue-gas filtration at 180 °C, with particulate loading up to 35 g/m³ and acid dew point as low as 125 °C, demands media that retain structural integrity while delivering consistent backwash efficiency. Our Dust & Flue-Gas Filtration range addresses this through material-specific thermal and chemical resilience—not generic “high-temp” labeling. These conditions occur in municipal waste incinerators, cement kilns, and biomass boilers where corrosion resistance and long-term permeability stability are non-negotiable for low O&M operation.
Material Selection Dictates Long-Term Permeability
PTFE dust filter bag media maintain stable airflow across 20,000+ hours when exposed to SO₂, HCl, and condensable organics. PPS dust filter bag offers cost-effective resistance below 190 °C but degrades rapidly above that threshold without oxidation inhibitors. Aramid dust filter bag provides excellent tensile retention up to 205 °C but exhibits hydrolytic vulnerability below pH 4.5 in wet flue-gas recirculation systems. Polyamide P84 dust filter bag delivers asymmetric pore structure for fine capture but requires strict moisture control—its hygroscopic nature accelerates fiber swelling if inlet humidity exceeds 15% RH.
Structural Support: Cage Design Impacts Bag Life
SS316 Filter Cages resist chloride-induced pitting in coastal or saline-laden airstreams where galvanized steel cages show visible corrosion after 14 months. Envelope Cages reduce localized abrasion at the top fold by distributing tension over a continuous radius, extending needle punched felt fabric filter bags service life by 3–5 months in high-velocity shaker applications. Flat Cages suit retrofit installations with space constraints but require precise alignment to avoid bag flutter; misalignment exceeding ±1.2 mm induces premature seam fatigue. In practice, we typically observe 22% fewer bag replacements per year when SS316 Filter Cages replace epoxy cages in dual-fuel boiler exhaust streams.
Surface Engineering for Critical Duty Cycles
PTFE coated filter bags combine base-fabric mechanical strength with surface-level chemical inertness—critical where sticky tars or ammonium bisulfate form below 150 °C. Anti-static filter bags prevent charge accumulation in explosive dust environments (e.g., coal pulverizer exhaust), but their conductive layer introduces a trade-off: reduced abrasion resistance at the surface, requiring tighter cage tolerances to avoid micro-scratching. Reverse pulse jet filter bags rely on rapid pressure differentials; their performance degrades if felt density exceeds 580 g/m², limiting dust cake release velocity. Pleated dust collector and baghouse filter bags increase surface area per footprint but demand rigid support structures to prevent pleat collapse under differential pressures above 2.8 kPa.
| Media Type | Max Continuous Temp (°C) | Acid Resistance | Hydrolysis Risk |
|---|---|---|---|
| PPS dust filter bag | 190 | High | Moderate |
| Aramid dust filter bag | 205 | Moderate | High |
| Polyester Filter Bags | 130 | Low | High |
| PTFE dust filter bag | 260 | Very High | Negligible |
This table shows absolute thermal and chemical limits—not design margins.
Where This Selection Does Not Apply
This selection does not apply to fluidized bed combustors operating above 280 °C with >20% oxygen content, nor to primary metal smelting off-gas containing elemental mercury vapor. It is unsuitable for continuous exposure to free chlorine gas or nitric acid mists. Avoid using polyester-based products—including Polyester Filter Bags and envelope filter bags—in any application where inlet temperature exceeds 130 °C or where condensation events are uncontrolled. These limits preclude use in certain metallurgical fume extraction scenarios without upstream quenching.
- Reverse pulse jet filter bags require minimum compressed air pressure of 5.5 bar for effective cake release
- Filter shaker bags need ≥0.8 Hz oscillation frequency to sustain backwash efficiency
- SS316 Filter Cages must be passivated post-welding to restore chromium oxide layer integrity
For cross-contamination-sensitive water treatment facilities handling reclaimed process water, consider our Liquid Filtration product line, which shares the same 316L stainless steel construction philosophy but targets dissolved solids removal. The Dust & Flue-Gas Filtration range remains purpose-built for dry particulate separation where thermal, chemical, and mechanical stresses converge. Measured data from third-party lab testing confirms that PTFE-coated filter bags retain >92% of initial permeability after 10,000 simulated cleaning cycles—provided cage geometry matches the bag’s radial expansion profile.
Common questions on dust & flue-gas filtration
How do I choose between polyester, PPS, Aramid and PTFE media?
Polyester and polypropylene cover normal-temperature needle punched felt. PPS, Aramid and polyamide P84 are the grades used where the gas runs hotter, and PTFE is the choice for aggressive chemistry. The finish matters as much as the polymer: singed, calendered, heat set, water and oil repellent and anti-static treatments all change how the dust cake releases.
What is the role of the bag cage?
The cage holds the bag open against the cleaning pulse or the shaker action. Cages are supplied in galvanized steel, SS304, SS316 or epoxy finish, with or without a venturi, and in flat, envelope or long jointed forms for 108 inch and 144 inch bags.
What does a PTFE coating change?
It moves the filtration mechanism from depth to surface, which is intended to improve dust release and reduce residual pressure drop. It adds cost, and it is not the right call for every dust, which is why the same felt family is also offered without lamination.