Study On Dust-Cleaning Mechanism Of Pulse-Jet Bag Filter

With the more and more increasingly stringent dust emission standards, the bag filter have been put into use more and more widely. In all kind of bag filters the pulse-jet bag filter is the most widespread and efficient one because of its good dust-cleaning effect, large capacity, safe and reliable and so on.The operation of the pulse-jet bag filter indicates that the working life of the bag and dust-cleaning effect are the most important parameters. The features of the bag directly influences the working life and the dust-cleaning effect also has a direct influence on the operation of the pulse-jet bag filter, which based on the article studies on the pulse-jet bag filter from the aspects of theory and experiment.In the article firstly the velocity and mass air flow of the nozzle are deduced by coercible gas heat insulating energy equation; then based on free-jet stream theory, the air flow and average energy of injecting profile are studied; and finally according to the functional mechanism of the cleaning air on the bag surface and dust layer, the calculation formulas of necessary jetting pressure, nozzle diameter, ejecting distance and ejector tube throat diameter under a certain dust load are obtained.In order to validate the theoretical results, the research launches a study on dust-cleaning mechanism of pulse-jet bag filter. The bag filter applied is2000mm in length,95mm in diameter.The results of the research indicate that theoretical values and experiment dates of the jetting distance and throat diameter of the ejector tube have a good coherence; the peak pressure increases with the jetting pressure, dust load and nozzle diameter, which improves the dust-cleaning effect. The peak pressure along the axial direction are uneven in the process of dust cleaning, the bottom is the maximum, the upper takes the second place and the middle is the minimum; the arrival time of the peak pressure are roughly the same, the duration of the pressure is greatly influenced by pulse duration. And also the stripping ratio in the different jetting pressures, pulse durations, dust loads and nozzle diameters are tested. The results indicate:the jetting pressure has an obvious positive influence on the dust-cleaning effect, and when it reaches Po=0.4MPa, the effect stabilizes; the pulse durations makes no influence on the dust-cleaning effect; and the role of the dust load is the same as the jetting pressure, and when it reaches m=0.9kg/m2, the effect stabilizes; when the nozzle diameter is largened, the dust-cleaning effect greatens too, but large diameter makes great air consumption, so we should choose the appropriate one in practice; the stripping force and ratio have a good correlation with each other, the relation can be described as0=1.0-exp[-E(F-C)λ].Based on the results through theoretical and experimental research above, the design method of dust-cleaning system of pulse-jet bag filter is proposed finally.