Optimisation and regeneration of ceramic flue gas filters
In cooperation with the project partner - BUT
Dedusting and filtration of flue gases from a coal or biomass boiler is a very important topic due to the increasingly stringent requirements for the discharge of particulate matter (PM) into the air. The majority of biomass boilers in operation, mostly of an older date of manufacture, are equipped with cyclone separators or multicyclones only. These technologies do not achieve the required ash removal efficiency and the boilers exceed the permitted emissions of VOCs. The dust removal from biomass boilers is specific to the high occurrence of ash in the form of unburnt particles of sawdust, bark or wood chips. Dedusting of large wood chip boilers is preferably solved by electrostatic precipitators. For smaller boilers with a capacity of 300 kW to about 2 MW, the purchase of an electrostatic precipitator is costly and therefore dust removal is solved by mechanical filters. However, mechanical fabric filters are totally unsuitable for dedusting biomass boilers as they are very susceptible to burning of the filter media, despite the use of special high temperature fabrics. The aim of the project is to develop and optimise filter units for flue gas dedusting using ceramic filter rods. Unlike fabric media, these are resistant to combustion and capable of operating up to 900 °C. However, problems still remain in real applications. First of all, finding the optimum filter area, regeneration of the clogged filter during operation, arrangement of the filter elements, the possibility of servicing without shutting down the boiler, fine-tuning the automatic ash removal system, etc. Thanks to the optimization, the high-temperature filtration can be further extended to other applications such as flue gas dedusting in hazardous waste incinerators, filtration from glass and cement kilns, dedusting in brick firing or melting furnaces of ferrous and non-ferrous metals and other special applications. This will create a unique technology with an extraction capacity of up to 16,000 m3/h unparalleled in the field of high temperature filtration.