Experimental Study of Gas Absorpiton in a Dry System and in a Wet System

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1. Introduction The development of low cost removal process of acid gases and dust particles in the flue gas from incinerators is desirable. A cyclone scrubber is one of the processes, which can absorb gases, separate particles, and decrease gas temperature simultaneously. Although some researches on cyclone scrubbers have been reported and mathematical models have been developed to understand the mechanism of dust separation in the cyclone scrubber, it has still not been clear enough. The main objective of this work is to elucidate the particle removal mechanism in a wet cyclone scrubber. 2. Experimental Apparatus Experiments were carried out in a small conical-cylindrical combined cyclone scrubber with 5.9 cm in cyclone diameter. Fly ash is fed as dust by a fluidized bed generator (model 3211, Kanomax, Inc. Japan) into the gas stream. Liquid is sprayed into the gas stream containing dust in the inlet duct of the cyclone. Dust separation efficiency was determined by the gravimetric analysis of the dust captured in the inlet and the outlet of the cyclone. The cumulative size and the size distributions are measured by a laser scattering particle size distribution analyzer (LA-910, Horiba, Ltd. Japan). 3. Dust Collection Efficiency The collection of dust particles on droplets is achieved by the inertial impaction and the turbulent diffusion affects [1]. This work assumed that the inertial impaction is predominant for the collection efficiency of the dusts and mainly takes place in the inlet duct of the cyclone. The single collection efficiency of an inertial impaction droplet can be described as [2] (1) is the inertial parameter or Stokes’ number and a = 0.25, b = 2 for Rep >> 1 [2]. The axial velocity of gas in the inlet d... ... middle of paper ... ...redicted values. It shows that the wet concept model under-estimates the collection efficiency at the smaller liquid flow rate, while the agreement is good at the larger liquid flow rates. However, for all liquid flow rates, the combination of the wet and the dry concept models is in agreement with experimental data both for the dry process and the wet process under the current experimental conditions. Fig. 3 Total dust collection efficiencies calculated versus liquid – gas ratio comparing with experimental data 5. Conclusion The experimental values for total collection efficiencies were compared with the values calculated from two models, the wet concept model and the combination of the dry and the wet concept model. The second one provides the best fit with the experimental data for the dust removal in the wet and the dry cyclone scrubber.

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