An Experimental and Numerical Study on the Cleaning of Pleated Bag Filters Using Low-Pressure Pulsed-Jets

Pulsed-jet cleaning is recognized as the most efficient method to regenerate bag dust collectors traditionally used in industrial processes to control the emission of particulates.In this study,non-woven needle felt filter bags with and without a film coating material have been analyzed considering different geometries(different number N of pairs of pleated filter bag sides)in the frame of dedicated low-pressure pulsed-jet cleaning experiments.The flow structure inside the bag and the response characteristics of its wall have also been analyzed numerically through a computational fluid-dynamics/structural-dynamics(CFD-CSD)unidirectional fluid-solid coupling method.As shown by the experiments,the peak pressure(P_(0))on the wall of the filter bag with N=8 and 12 is higher,which indicates dust can be removed more effectively in these cases.The peak pressure on the wall increases first and then decreases along the direction of the bag length,while the peak pressure of the pleated filter bag with nonwoven needled felt film coating is greater than that without film coating.A comprehensive analysis of the time variation of acceleration,deformation,strain,stress and other factors,has led to the conclusion that the pleated filter bag with N=12 would be the optimal choice.

CFD Simulation of a Bag Filter for a 200MW Power Plant

The combustion of pulverized coal inevitably produces dust and other harmful substances.For these reasons,the optimization of de-dusting procedure and equipments is an aspect of crucial importance towards the final goal of making this source of energy more sustainable.In the present work,the behaviour of a“bag filter”is simulated using Computational Fluid Dynamics(CFD).More specifically,three possible approaches are used,differing with respect to the level of fidelity and the partial utilization of empirical data.The outcome of these simulations is mutually compared and finally discussed critically in the light of available experimental results.

The Elaboration of Flow Resistance Model for a Bag Filter Serving a 200 MW Power Plant

On the basis of a macro flow resistance method and the Darcy Theory,a mathematical model is elaborated to characterize the flow resistance of a bag filter serving a coal-fired power plant.The development of the theoretical model is supported through acquisition of relevant data obtained by scanning the micro structure of the bag filter by means of an electron microscope.The influence of the running time and boiler load on the flow resistance and the impact of the flow resistance on the efficiency of the induced draft fan are analyzed by comparing the results of on-site operation tests.We show that the initial operation time and the table operation time are linearly related to the flow resistance of the bag filter;with the increase of boiler load,the flow resistance of the bag filter rises approximately as a quadratic function;with the rise of resistance,the power consumption of the induced draft fan increases while the efficiency of the induced draft fan decreases.

干法水泥厂收尘的设计与实践

Cement plant are dust porducing enterprises. Dust loading from process has the feature of enviornment enclosure and large ehaust gas emission. At present, two dedusting methods by precipitation and filtration bag filfer and E.P.are generally used in cement plants. From the view of environmental and water source savings, bag filters will be more and more used in future. For dust emission from materials crushing and handling the optimal method is to make combination of initiative and possitive amnagement and treatment.

Predicting effect factors of dual bag filter system for PCDD/Fs removal from hazardous waste incineration flue gas

The dual bag filter(DBF)system is a new polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans(PCDD/Fs)emission control technology that has more efficient(PCDD/Fs)removal performance,a higher activated carbon utilization rate and less activated carbon consumption compared with the traditional single bag filter system.Moreover,few studies have been relevant to the mechanism of the PCDD/Fs removal process in the DBF system,and the selection of operating conditions of the DBF system lacks an academic basis.This study established a PCDD/Fs removal efficiency model of activated carbon injection combined bag filter(ACI+DBF)system for hazardous waste incineration flue gas and predicted the crucial effect factors.New adsorption coefficients k_(1)=532,145 Nm^(3)/(mol s)and k_(2)=45 Nm^(3)/(mol s),and the relationship expression between the number of available adsorption positions of recycled AC(AAC′)and cycle times(n)are proposed in the model.The results verify that the model error was below 5%.In addition,the PCDD/Fs removal efficiency model predicts that in a certain range,the PCDD/Fs removal efficiency increases with increasing activated carbon injection concentration.The best cycle number of activated carbon was less than 3,and the ratio of circulating activated carbon to fresh activated carbon in second bag filter(SBF)should be controlled at 7–8.

Removal of PCDD/Fs and PCBs from flue gas using a pilot gas cleaning system

A 100 Nm3 /hr capacity pilot scale dual bag filter （DBF） system was tested on the flue gas from an actual hazardous waste incinerator （HWI）, the removal efficiency of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans （PCDD/Fs） and polychlorinated biphenyls （PCBs） was also studied. The first filter collected most of the fly ash and associated chlorinated organic; then activated carbon （AC） was injected and used to collect phase chlorinated organic from the gas. Concentrations of PCDD/Fs and PCBs after the DBF system were 0.07 and 0.01 ng TEQ/Nm3 , respectively, which were both far below the national emission standard. Comparing with the original single bag filter system, the PCDD/Fs concentration dropped a lot from 0.36 to 0.07 ng TEQ/Nm3 . Increasing AC feeding rate enhanced their collection efficiency, yet reduced the AC utilization efficiency, and it still needs further study to select an appropriate feeding rate in the system. These results will be useful for industrial application and assist in controlling emissions of PCDD/Fs and other persistent organic pollutions from stationary sources in China.