Compressed fiber bed (core layer): Filled between the inner and outer mesh cylinders. The fiber material depends on the operating conditions; common materials include Special Glass Fibers, Polypropylene (PP), Polytetrafluoroethylene (PTFE), Ceramic Fibers. These fibers are very fine and highly compressed to achieve a specific bulk density.

Drainage layer (preventing secondary entrainment): Modern high-efficiency fiber beds often have an additional layer of coarse fibers on the downstream side (gas outlet side) to quickly guide the accumulated liquid downwards, preventing high-velocity gas from blowing the liquid away again.

Mounting flanges and bases: Used to fix the demister to the tube sheet inside the tower body and ensure airtightness.

FRP  470  411  wire cage

PP  PTFE  wire cage

304  316  316L  904L  stainless steel wire cage

Filtearth Fiber Bed Mist Eliminator, also known in industry as a Candle Filter or Fiber Demister, is a highly efficient industrial purification device specifically designed to remove extremely fine droplets, submicron-sized aerosols (droplet diameter less than 1 micrometer), and soluble solid particles from airflow.

Compared to ordinary wire mesh demisters or baffle demisters, its biggest advantage lies in its ability to capture those submicron-sized particles that are suspended in the gas like smoke and are extremely difficult to separate.

Working Principle and Capture Mechanism Gas typically flows horizontally through the fiber bed from the outside in (or from the inside out). When gas containing droplets passes through the dense fiber network, the droplets are primarily captured through the following three physical mechanisms:

Inertial Impaction:Suitable for larger particles (> 3 micrometers). When the streamlines bend at the fiber, large particles, due to their greater inertia, cannot turn in time and directly collide with the fiber surface and are captured.

Direct Interception:Suitable for medium-sized particles (1-3 micrometers). Particles move with the airflow lines; when the distance between the airflow line and the fiber is less than the particle radius, the particle surface contacts the fiber and is adsorbed.

Filtearth Fiber Bed Mist Eliminator are typically cylindrical tubes (resembling a giant candle) and mainly consist of the following parts:

Concentric inner and outer mesh cylinders (support grids): Usually made of corrosion-resistant metals (such as stainless steel, titanium alloy) or plastics (such as FRP, PP, PTFE), providing mechanical support for the internal fibers.

Brownian Diffusion:Suitable for extremely small submicron particles (< 1 micrometer). Due to their extremely small mass, these particles are constantly bombarded by gas molecules, undergoing irregular "Brownian motion" (random swaying). This violent displacement greatly increases the probability of particle collision with the fiber. This is the core secret behind the fiber bed demister's near 100% capture of ultrafine droplets.

Self-cleaning mechanism: Countless tiny droplets captured aggregate on the fiber surface, forming a continuous liquid film. Under gravity, the liquid flows downwards along the fibers to the bottom and is discharged from the system through a drain pipe. This "capture and discharge simultaneously" characteristic gives it excellent self-cleaning capabilities.

Superior Collection Efficiency: Nearly 100% collection efficiency for droplets larger than 1 micrometer; even for the most difficult-to-capture submicron-sized acid mist (smaller than 1 micrometer), efficiency typically reaches 99.5% to 99.99%.

Extremely Long Service Life: Due to the absence of moving parts and the highly specialized fiber materials (such as highly corrosion-resistant glass fiber), a single fiber bed can be used for years or even decades without replacement, provided the process and operating conditions are appropriate.

Relatively Stable Pressure Drop: Although the initial investment and pressure drop are higher than ordinary wire mesh demisters, its self-cleaning and drainage function ensures a stable pressure drop during operation over a long period.

Elimination of Visible Plume: Completely eliminates "blue smoke" or "white smoke" in industrial exhaust gases, helping factories meet stringent environmental emission standards.

Finished installation diagram

On-site working conditions and environment

Support reinforced ring ribs in the center cage

Assembled Fiber Mist Eliminator element

Filtearth Fiber Bed Mist Eliminator, due to their superior ability to handle ultra-fine droplets, have become standard equipment in many industries with high corrosion and high purity requirements:

Sulfuric Acid Industry and Metal Smelting: This is the most classic application. Used after drying and absorption towers in sulfuric acid production to capture extremely fine sulfuric acid mist (H₂SO₄ mist), protecting downstream heat exchangers and catalysts from corrosion.

Chlor-Alkali Industry: Used for demisting after cooling wet chlorine gas, and for removing trace amounts of brine or alkali from hydrogen and chlorine gas streams.

Nitric Acid and Phosphoric Acid Production: Intercepts valuable acid mist entrained in process gases, reducing material loss.

Petrochemical and Plastics Processing: Removes oil mist from compressor outlet gas streams, or treats organic "blue smoke" aerosols generated during plastic curing and textile finishing processes.

Filtearth Fiber Bed Mist Eliminator is widely used in the purification of mist-laden exhaust gases in chemical, environmental protection, and other fields. To ensure its long-term demisting efficiency and prevent excessive pressure drop, scientific preventative maintenance must be performed：

1. Regularly Monitor Pressure Drop (Key Indicator)

Pressure drop is the most direct indicator of fiber bed performance.

✅Daily Inspection: Differential pressure gauges (such as U-tube manifolds or differential pressure transmitters) should be installed at the inlet and outlet, and an operation record sheet should be established.

✅Trend Analysis: Changes in pressure drop reflect the accumulation of captured mist and particulate matter between the fibers. If the pressure drop increases sharply in a short period of time, it usually indicates blockage.

Set Warning Values: When the pressure drop reaches the equipment's design limit, the filter element must be cleaned or replaced.

2. Cleaning and Regeneration

The cleaning strategy varies depending on the composition of the process gas:

✅ Water Washing/Solvent Flushing: For water-soluble substances or soluble organic deposits, online/offline cleaning can be performed via backflushing or spraying. Note: Ensure the flushing solution does not damage the fibrous media (e.g., chemical compatibility with glass fibers).

✅ Chemical Cleaning: If the deposits are sparingly soluble salts or polymers, acidic or alkaline solutions or specialized chemicals may be required.

✅ Steam/Gas Purging: In certain processes, purging with superheated steam or inert gas can remove some physical deposits.

3. Regular Structural Inspections

During shutdown maintenance, the following physical structures should be inspected:

✅Sealing Check: Inspect the installation seals and gaskets of the fiber bed filter element for aging or damage. Any leaks will cause gas to "short-circuit" (passing directly through unfiltered gas), significantly reducing demisting efficiency.

✅Filter Element Condition: Observe the surface of the fiber media for signs of sintering, breakage, collapse, or corrosion.

✅Support Structure: Inspect the filter element support frame and fastening bolts for rust or looseness.

✅Housing and Spray System: Inspect the inner wall of the housing for corrosion spots; confirm that the internal nozzles are not clogged or worn, and ensure uniform spray coverage.

4. Operating Condition Management (Preventative Maintenance)

Reduce maintenance frequency by optimizing process parameters:

✅Control inlet gas velocity: Excessive gas velocity can lead to flooding, secondary water carryover, and accelerated mechanical damage to the filter media; insufficient gas velocity may result in decreased collection efficiency. Ensure operation within the rated design range.

✅Prevent crystallization/polymerization: If easily crystallizing substances are present in the process gas, consider using process methods (such as maintaining the gas temperature above the dew point or continuous micro-spraying) to prevent premature deposition at the fiber bed inlet.

✅Pretreatment system: Inspect the upstream pre-dust removal or pre-cooling facilities. A decrease in upstream dust removal efficiency can cause premature clogging of the fiber bed.

5. Replacement Strategy

The filter element must be replaced when cleaning fails to restore the pressure drop to its initial level, or when significant chemical degradation/physical damage occurs to the fibrous media.

✅Replacement Cycle Record: Record the filter element's lifespan to help predict future spare parts needs.

✅Installation Specifications: Ensure absolute verticality during replacement to prevent seal failure.

Maintenance Tips:

✅Fiber bed filter elements are highly precise and fragile components (especially those made of special glass fiber). When working inside, wear appropriate personal protective equipment and strictly follow the manufacturer's "Inspection and Operation Procedures" to avoid damaging the fiber media due to tool impacts.

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