Author：yilida Time：2026-10-22 15:30:36 Number of views：145Second-rate
Cement kilns, sintering machines, electric arc furnaces and industrial boilers all produce hot, often chemically aggressive gas. Standard polyester felt fails quickly above roughly 130 °C, so high-temperature dust removal is decided by three things: the filter media temperature window, gas conditioning that keeps the stream above its acid dew point, and a cleaning strategy that suits the dust load. Get these right and a baghouse will run for years; get them wrong and bags fail within weeks.
| Gas temperature | Typical media | Key caution |
|---|---|---|
| < 130 °C | Polyester needle felt | Hydrolysis risk in hot, humid gas |
| 130 – 180 °C | Acrylic / aramid blends | Check chemical resistance to acid and NOx |
| 180 – 260 °C | Glass fiber, PTFE membrane laminate | Avoid folding damage; verify dew point continuously |
| Peaks above design | Emergency cooling / bypass | Install temperature interlock and alarm |
Remember that the limit is a continuous operating temperature with a much shorter permitted peak. Always specify the peak duration and frequency the plant expects, and require a temperature interlock that protects the bags during upsets.
Most hot-gas failures are not caused by heat but by condensation below the acid dew point, which attacks bags, cages and the housing. Options include air-to-air or water-cooled heat exchangers, ambient air dilution with an automatic damper, or waste-heat recovery where the energy has value.
Insulate and, where needed, trace-heat the housing and hopper to keep surfaces above dew point.
Pre-heat the baghouse before introducing process gas on start-up.
Monitor inlet temperature continuously and interlock the emergency dilution damper.
Remove coarse, abrasive fractions with a cyclone or settling chamber before the bags.
Each compartment is isolated for cleaning or inspection while the rest of the plant keeps running. This is the preferred architecture for very large cement and metallurgy lines: maintenance can be done without stopping production, and cleaning is gentler on high-temperature glass fiber media.
Online cleaning with compressed air, compact and responsive. Suitable for moderate hot-gas volumes with stable conditions and dry, oil-free compressed air.
Cages must be concentric, smooth-welded and corrosion-protected; burrs are a leading cause of bag abrasion.
Tube-sheet flatness and hole tolerance determine sealing; specify gasket or snap-ring details explicitly.
Venturi alignment with the pulse nozzle is critical — misalignment wastes air and cleans unevenly.
Use heavy anti-corrosion steel structure and weather protection for outdoor installations.
Hoppers need enough slope, plus a star discharger, heating or vibration pads for cohesive ash.
Design the outlet to the regulation you must meet, not to a generic figure. Typical tools: continuous opacity or dust monitoring, differential-pressure trending per compartment, and bag-leak detection to locate a failed bag before outlet concentration rises. Keep commissioning test reports, media certificates and a maintenance log — inspectors ask for all three.
Hot-gas plants should stock one compartment's worth of bags and cages, plus pulse valves, diaphragms, and discharge spare parts. Plan bag replacement around the production calendar and record ΔP and temperature trends so the next campaign can be forecast rather than reacted to.
Around 260 °C with glass fiber or PTFE-laminated media, and higher only with special alloys or ceramic elements. Polyester is limited to about 130 °C continuous.
Commonly condensation below the acid dew point during warm-up, over-temperature excursions, or cage burrs. Review the start-up procedure and inspect failed bags for the tell-tale pattern.
Large kiln and raw-mill lines usually favour compartmentalized offline baghouses for maintenance without shutdown; smaller or retrofit projects often use pulse jet.
Typically 18–36 months depending on temperature cycling and chemistry. Trend differential pressure and outlet readings rather than replacing on a fixed calendar.
Before requesting a proposal, collect these five items: airflow (m³/h), dust type and particle size, gas temperature, available installation space and the local emission limit. With these five figures, a sized selection, filter-media recommendation and spare-part list can be produced quickly and accurately.
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