Development of multi-cyclone for fine dust emission control

Abstract

The aim of the study was to develop an optimized design multi-cyclone fine particulate emission control system named as MR-deDuster to fulfil the stringent environmental regulatory requirement of Malaysia Clean Air Regulation 2014. This is due to the existing multi-cyclones used do not effectively reduce the emissions level within the legislative limit at all times. The theoretical background of the unit was developed based on the modifications of established design equations available in the literature. The modified Lapple model with different definitions of maximum radial distance travelled by a particulate designated as W, as well as Leith and Licht model were used to predict the collection efficiency of the unit. Meanwhile, the modified Shepherd and Lapple model was used to predict the pressure drop across the unit. The predictions were later compared with the actual data obtained experimentally and the best method to represent the actual performance of the unit was identified. The computational fluid dynamics (CFD) model template in ANSYSFluent software was used to predict the flow pattern within the MR-deDuster unit to assist in understanding its fluid flow and the particulate collection mechanism. The actual pilot plant of the unit was fabricated based on the optimum design configurations and tested experimentally under various volumetric gas flow rates ranging from 0.13 to 0.21 m3/s. To verify the theoretical findings, two different types of particulates samples, palm oil mill boiler fly ash (POFA) and PreKotTM were tested. The result showed that the unit was able to attain high collection efficiency at a relatively low pressure drop based on the theoretical and experimental findings, which highlighted the ability of the unit as an efficient particulate emission separator. Both theoretical and experimental studies also demonstrate that the increase of volumetric gas flow rate results in a reduction of cut diameter with an increase of fractional and overall collection efficiency as well as pressure drop of the MRdeDuster. However, as observed in the experimental study, the collection efficiency reduced at a volumetric gas flow rate of 0.21 m3/s due to saltation velocity phenomenon. The modified Lapple model of W = D-De/2 was identified as the closest model to represent the actual collection efficiency of MR-deDuster. Meanwhile, the modified Shepherd and Lapple model with constant K = 3.7 was accepted as the model to represent the actual pressure drop of the unit. In conclusion, the development of MR-deDuster unit is able to offer a better multi-cyclone unit in capturing the fine particulate for many industries as well as providing new theoretical analysis on multi-cyclone.