Hot gas filtration ensures clean air

The latest advances of hot gas filtration technology are addressed in the following contribution by Manfred Salinger. The full version of this article appears in the November/December issue that has been mailed globally and is also now available free of charge in the digital archive*.

Hot gas filtration ensures clean air

Removing dust from particulate-contaminated industrial flue gases at high temperatures early enough is a requirement that makes sense not only from an economic but also from an ecological perspective. However, where synthetic fibre filters reach their limits at around 250°C, with ceramic filter elements flue gases up to 1000°C can be filtered. The microporous filter material made of high temperature wool boasts its strengths. RATH has been developing innovative hot gas filter elements for many years, because those who are familiar with refractory technology are also predestined for hot gas filtration.

Emissions reduction goals

Fine dust, sulphur dioxide emissions and nitrogen emissions caused by high melting temperatures can all cause poor air quality. As a result, the glass, cement and metal industries, chemicals and petrochemicals as well as waste incineration and recycling plants – like many other industrial sectors – face the same challenge: Filtering and dedusting flue gases and pollutants as efficiently as possible and reducing their emissions.

For many decades, synthetic fabric filters and bag filters have been used as standard for filtering and dedusting. However, these reach their limits when dedusting and filtering industrial flue gases in the high temperature range. They cannot withstand high temperatures and pollutants can no longer be filtered appropriately.

It is different with ceramic filter elements, which can be used to filter hot gases up to 1000°C. Cooling the gases for the purpose of filtering becomes obsolete, saving companies money and energy.

But this type of filtration also has other advantages. The dry particulate separation enables the preservation of process gas and dust properties. Another positive is associated with the cost-effective protection of catalysts. In addition, thanks to ceramic hot gas filtration, downstream systems are also protected by avoiding corrosion and deposits.

This type of filtration also benefits the environment. Because no water is required for this type of filtration, the problem of wastewater is also eliminated.

Highly efficient hot gas filter cartridges

With FILTRATH, RATH has developed a highly efficient hot gas filter cartridge system for the filtration of hot gases. The hot gas filter cartridges that RATH has developed have consistently stable filter properties over the entire temperature range of 250°C-1000°C.

Therefore, they can be used in existing flue gas processes without temperature adjustment. Another advantage of the RATH filter cartridges is that they are light, highly porous and have a very low pressure drop.

The excellent quality of these products is based on decades of manufacturing expertise in the refractory industry, especially in the field of high temperature insulation wool. The FILTRATH ceramic filter elements consist of vacuum formed, in-house high temperature wool. This brings valuable synergy effects and additional scope in the further development of innovative filter elements.

Catalytic filter cartridges for multiple filtering

FILTRATH CAT catalytic filter elements were developed for multi-pollutant emission control. These rigid yet highly porous and catalytically-coated ceramic filter elements are used for multi-pollutant control of (fine) dust, acidic gases, dioxins and nitrogen oxides used in hot gas flows (at temperatures of 250°C-420°C). RATH delivers tailor-made solutions to ensure optimal catalytic performance.

Filter cartridges of variable lengths

RATH also offers tailor-made solutions in terms of the length of the hot gas filter cartridges. Using a specially developed ‘screw and glue’ connection, filter cartridges up to a length of 6m can be produced from several segments. The segments are assembled into a long filter element when the filter cartridges are installed on-site.

This smart solution enables the use of long filter elements even where the spatial conditions do not allow it. It is an innovative technology that some cement plants have already opted for with the world’s first filter systems with 6m long filter elements in use.


FILTRATH is a registered trademark of RATH

Image: RATH hot gas filtration reactor system equipped with ceramic filter elements, viewed from below.

About the Author: 

Manfred Salinger is Managing Director at RATH
Filtration GmbH

Further Information: 

RATH AG, Vienna, Austria
tel: +43 1 513 44 27-2110

* The full version of this article appears in the November/December issue that has been mailed globally. To increase accessibility in the current environment, the digital version of this issue can be read free of charge in its entirety alongside back copies in the Digital Archive (sponsored by FIC) at

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