Rauchgasreinigung Flue Gas Cleaning - Hitachi Power Europe ...

Cyclones and MulticlonesFiltering of dry flue gasesThe separation principle is centrifugal force separation. The flue gases are set into circularmotion in cylindrical separation tanks, whereby the rotating flows produce high centrifugalforces which hurl the dust particles towards the exterior wall.Skizze MultiklonSchematic of multiclone1While the cleaned gas is sucked upwards by a centrally installed duct, the dust particlesdescend to the outer wall on a helical course into the dust bunker, owing to their inert mass.Although centrifugal force separation units with their low level of pressure loss are employedfor flue gas temperatures of up to 1000 °C, due to the current high level of dedusting requirementsthey are now primarily only used as rough and preliminary separators as well as fordust recycling systems. Centrifugal force dedusters react sensitively to changes of the exhaustgas velocity and achieve degrees of separation of merely 50 % – 90 %, depending onthe type of dust.1 ReingasClean gas2 RohgasRaw gas3 StaubDust2As rough or preliminary separators, they protect boiler heating surfaces, heat exchangers aswell as ventilators from wear and tear or the accretion of deposits, and relieve downstreamhigh-performance dust removers, such as for example electrostatic filters. Cyclones with alower limit of efficiently precipitable dust-dependent particle size of 5 to 10 μm are built withdiameters between 0.5 and 5 m, depending on the gas quantity.3The design and arrangement of the multiclone gas connections can be varied across a broadrange. They require less space for the same throughput and can therefore be more easilyupgraded in existing plants. The filtration systemconsists of a multitude of separationpipes with diameters of about 230 mm, configuredin parallel. Due to the small diameterof the multiclone pipes, greater centrifugalMultiklonanlageMulticlone system11 ReingasClean gas2 RohgasRaw gas3 TauchrohrImmersion pipeforces than in a large cyclone can be generatedvia the shovel nose fixtures, wherebyrelatively fine dusts with a particle size as of 22 34 AbscheideraumSeparator chamberto 5 μm can also be separated out.The distribution of the gas volume to manymulticlone pipes leads to smaller specificdust loads of the individual separation surfaces,whereby a long service life can beachieved even in case of highly abrasivedusts.4Flue Gas Cleaning 17