Choose ceramic plant filter bags by separating raw-material, press, spray-dryer and kiln duties. Assess PPS suitability, moisture and filtration area.
Preparation method: manufacturer application information, process risks and engineering examples with explicit assumptions were assessed together. Numerical examples are not field measurements.
Can one filter bag specification serve an entire ceramic plant?
Ceramic plant filter bags should be selected by the process generating the dust, not by the industry label. Raw-material transfer and press extraction do not share the temperature and moisture conditions of spray-dryer exhaust. Kiln gas needs a separate chemical assessment. PPS is a candidate for certain hot, moist streams, not a standard solution for every ceramic process. Establish the actual gas conditions at the bags before selecting media, surface treatment, filtration area and mechanical fit together.
This guide supports maintenance and purchasing teams preparing specifications for tile, porcelain and related ceramic processes. The calculation and diagnostic scenario are illustrative, not measurements from a customer plant. A fabric that performs well at one installation should not be copied to another line without checking temperature, gas analysis and cleaning arrangements.
Dust collection principle: separate the process streams first
In a baghouse, particles are captured at the fabric surface and in the developing dust cake as gas passes through. Cleaning releases the cake into the hopper. This mechanism must be distinguished from the treatment of sticky droplets, condensing vapour and gaseous contaminants. A filter bag does not remove all of those pollutants by the same mechanism. Fitting bags to kiln exhaust therefore does not mean that every gaseous component has been treated.
| Process Dew Point | First condition to investigate | Impact on selection |
|---|---|---|
| Raw-material unloading and dry milling | Particle distribution, abrasion and extraction balance | Evaluate suitable lower-temperature media first |
| Press and transfer extraction | Fine fraction, air leakage and simultaneous operation | Check surface treatment against actual flow |
| Spray-dryer exhaust | Moisture, temperature transitions and stickiness | Screen candidates including PPS for condensation and gas chemistry |
| Kiln flue-gas treatment | Temperature, acidic components and treatment process | Select bags as part of the complete treatment system |
When should PPS be considered or rejected?
Assess temperature and moisture together when evaluating PPS. Resistance to hydrolysis does not imply unlimited oxidation resistance. Compare oxygen, oxidising components, continuous temperature and excursion duration against the technical data sheet for the selected product. Daily average temperature is insufficient: investigate the conditions experienced during start-up, shutdown, fuel changes and air leakage.
On a dry raw-material line within the relevant limits, PPS should not replace suitable polyester merely because it costs more. Conversely, a dry-service temperature rating does not establish polyester suitability for a hot, moist exhaust. Do not finalise a PPS specification with unknown gas chemistry; resolve the missing information first. A membrane does not remove the chemical limitations of the underlying felt.
Fine dust, membranes and mechanical compatibility
Assess the fine fraction and abrasive particles, not only average particle size. Fine dust penetrating the felt, the required outlet concentration and residual resistance after cleaning inform the choice of membrane or surface treatment. For coarser mineral dust, inlet distribution and local abrasion may dominate. Neither universal membrane use nor universal rejection is justified for ceramic dust.
Measure finished bag diameter, cage outside diameter, tube-sheet opening, sheet thickness and attachment separately. A used bag may have shrunk, so the sample alone is not a manufacturing drawing. Cage burrs, protruding welds and poor seating can defeat the benefits of new media. Verify pulse settings and venturi compatibility for the selected construction; higher pressure is not an automatic cure for poor cleaning.
Filtration area calculation: a worked example
Assume an actual inlet flow of 18,000 m³/h, an active cylindrical bag length of 3.0 m, a diameter of 0.16 m and 240 bags all online. The active lateral area per bag is A = π × 0.16 × 3.0 = 1.508 m², giving approximately 361.91 m² in total. Face velocity is v = 18,000 / (60 × 361.91) = 0.829 m/min. This is not a recommended velocity; it shows the loading resulting from the stated geometry.
Suitability still depends on fine-particle content, stickiness, cleaning capacity and available net area. If a compartment is isolated, not every bag remains online. Calculated active area is not fabric purchasing area: closed ends, seam allowances and inactive portions require separate treatment. Flow stated in normal cubic metres is also not interchangeable with actual flow at the hot filter inlet.
Illustrative diagnosis: differential pressure rises at morning start-up
Suppose a collector operates steadily during the day but shows rising differential pressure and hardened cake after a cold start. Incorrect fabric weight would not be the only explanation. Review the temperature timeline, gas moisture, cold zones and insulation together. If condensation is confirmed, installing more expensive bags without changing the operating conditions does not eliminate the cause.
Inspection must follow safe shutdown and site procedures. Check the differential-pressure instrument and impulse lines, actual flow, hopper discharge and cleaning system separately. Hantech evaluates corrective work through trends at comparable production load and outlet performance, not one low pressure reading. Low differential pressure accompanied by increased dust discharge also warrants a leakage and installation investigation.
What should you send with a quotation request?
Include the process point, bag quantity and dimensions, attachment photographs, cleaning method, flow measurement conditions, continuous and excursion temperature records, moisture and available gas analysis. Dust characteristics, pressure trends, failure photographs and required outlet performance strengthen the selection basis. Identify missing data explicitly and compare quotations against the same technical data sheet requirements, dimensional tolerances and sample approval criteria.
- Explore filter bag options
- Assess cage and bag compatibility
- Request a technical quote for your ceramic process
Frequently Asked Questions
Does every ceramic plant use PPS bags?
No. Raw-material, press, dryer and kiln streams require separate assessment. PPS suitability must be checked against the selected product's temperature, moisture and gas-chemistry limits.
Which data come first for a spray-dryer filter?
Actual flow, the temperature timeline and moisture are needed together. Do not select fabric by name without assessing condensation and stickiness.
Will a membrane bag solve a moisture problem?
Not on its own. It can support surface filtration, but condensation causes and the chemical suitability of the supporting media need separate attention.
Is an old sample enough to order new bags?
A sample is useful, but shrinkage and wear can be misleading. Verify it against the cage, tube sheet and attachment dimensions.