Dust separation performance

The dust removal efficiencies referred to a dust separator a characteristic of the cleaning performance.

Definitions

The dust separation performance is expressed

• as a dust concentration  c ₁ in the purified gas ( clean gas )
• as the degree of separation or separation  η (proportion of the separated particles in the total amount) or
• with depth filters also as filter quality (higher filter quality corresponds to a larger positive value of q)

${\displaystyle q=-{\frac {lnP}{\Delta p}}}$

With

• the penetration (proportion of the total amount of particles that have penetrated  into the clean gas ); the following applies: ${\displaystyle P={\frac {c_{1}}{c_{0}}}}$ ${\displaystyle c_{1}}$ ${\displaystyle c_{0}}$ ${\displaystyle P=1-\eta }$
• the differential  pressure Δp (equivalent to the energy expenditure) across the separator
• the natural logarithm . ${\displaystyle ln}$

First and foremost is the question of the required purity , but - like the filter quality - taking into account the energy consumption . A cost-benefit estimate can be made using the Filter Utility Factor (FUF) , which takes into account changes in the degree of separation and differential pressure as well as the acquisition costs .

Depending on the requirements, there are also certain particle filter classes available for depth filters , but these are only suitable for rather low dust concentrations (<< 1 g / m³) (for example in air conditioning systems or as air filters in cars).

In industrial dedusting

In large-scale industrial dedusting (e.g. power plants, foundries , mills, etc.) with dust concentrations in the range from a few g / m³ to over 1000 g / m³, there are no particle filter classes, u. a. because of the emission behavior of the surface filters used there, which is strongly dependent on the operating mode and dust . The selection of the suitable separator or, when filtering the filter medium, is mainly based on empirical values .

The following table gives an overview of the typical dust separation performance of methods for large-scale industrial dedusting. In individual cases, however, the results in industrial practice may differ significantly from the information provided. For example, scrubbers and cyclones that work at medium and low pressure generally have a lower dust separation efficiency.

Performance of dust collectors

technology	Dust concentration in the clean gas after cleaning
electrostatic precipitator (wet or dry)	<50 mg / m³
High performance scrubber	<50 mg / m³
Surface filter	<10 mg / m³
Surface filter with ePTFE membrane	<1 mg / m³

Source: Decision 2001/379 / EC, Annex 2

See also

• Dust holding capacity

literature

• Elke Schmalz: Highly voluminous non-woven fabrics for the separation of coarse and fine components from gaseous media . Chemnitz September 30, 2002 ( tu-chemnitz.de [PDF] Dissertation, Faculty of Mechanical Engineering at the Technical University of Chemnitz).
• Friedrich Löffler : Dust separation . Georg Thieme, Stuttgart et al. 1988, ISBN 3-13-712201-5 .
• Friedrich Löffler, Hans Dietrich, Werner Flatt: Dust separation with bag filters and pocket filters . 2nd, revised edition. Vieweg, Braunschweig 1991, ISBN 3-528-18566-X .

Individual evidence

1. ^ Albert Podgórski: Optimization of aerosol filtration in fibrous filters. In: Abstracts of the European Aerosol Conference 2003. Held in Madrid, Spain, August 31 - September 5, 2003 (= Journal of Aerosol Science. Volume 34, Supplement 2, ISSN  0021-8502 ). Volume 2. Pergamon Press, Oxford et al. 2003, pp. 1195 ff.
2. ↑ Decision of the Council of April 4, 2001 on the approval - on behalf of the European Community - of the Protocol to the 1979 Convention on Long-range Transboundary Air Pollution Concerning Heavy Metals (2001/379 / EC). Appendix: Protocol to the 1979 Convention on Long-Range Transboundary Air Pollution concerning Heavy Metals. Appendix III: Best Available Techniques to Control Emissions of Heavy Metals and Their Compounds from the Categories of Sources listed in Appendix II. Table 1. In: Official Journal of the European Communities . L 134, May 17, 2001, p. 51.