Dust removal in scrubbers - State oft the art and challenges

Dr. Damian Pieloth, Technical University of Dortmund, Germany

Description oft dust particle precipitation due to inertia could be improved significantly by simulation during the recent years. Established calculation method can be applied to scrubbers when the drop size distributions are well known together with the gas flow and when the entrainment behavior into the expanding spray can be sufficiently described. That is the case for jet scrubbers as well as for rotary scrubbers. Due to the radial decay of the drop density a repeated contact to the gas, carrying the dust particles is essential for the latter and a multistage operation is inevitable. The interaction of cleaned gas volumes in shape of clean alleys within the gas phase is still problematic, as a full mixed state of gas and particles is assumed usually for successive drops in the calculations. Considering the actual mixing effect could provide some improvement. The same is true for observance of the Stefan-flow in case of evaporating drops, or taking into account electrostatic charges of drops and particles.

Drop breakup at sufficient relative velocities between drops and gas as present in venturi-scrubbers can quite well be characterized based on known facts. However the effect of simultaneous breakup and capture of particles is still unknown. Research efforts are till needed on that issue. The same is true for coalescence of drops that should be included into the calculation. In general washing columns are regarded as low effective even though they provide high residence time of gas required for the diffusional precipitation of very small particles x < 500 ┬Ám beyond the inertia effect. The small specific surface area between the liquid and gas phase is surely disadvantageous. Desintegrators as Theisen-scrubbers providing intensive renewal of interfaces as well as other designs seem to be well suited for that task....

Session: K5 - Keynote Lecture V
Day: 12 October 2016
Time: 10:45 - 12:00 h