What Factors Affect the Efficiency of the Dust Filter Efficiency Test System

First, the filter speedDust filter filter wind speed v refers to the average speed of the flue gas through the bag surface, v = Qt / 60F. Among them, Qt is the flue gas flow through the filter bag, m3 / h; F is the total area of ​​the filter bag, m2. The choice of filtration speed to consider the economy, filter bag life and filtration efficiency and other factors. When the same dust quality is accumulated on the surface of the bag, the accumulated dust collection rate decreases significantly with the increase of the filtration rate. In addition, the choice of filtration speed and cleaning methods, cleaning system, dust characteristics, inlet dust concentration and other factors are closely related. In general, for the low-pressure pulse jet cleaning dust filter speed ≤ 1.0m / min, additional dust pretreatment device after the filtration rate ≤ 1.1m / min; backflush cleaning method filtration speed ≤ 0.8m / min; dust Particles smaller, or the entrance of dust concentration is high, dust viscosity should be reduced when the filtration rate, reduce the filtration rate can improve the efficiency of filtration and extend the service life of the filter bag.

Second, the bag filter resistanceThe resistance of the bag filter determines the energy consumption, filtration efficiency and cleaning cycle of the dust removal system. It is related to the structure of the dust collector, the filter bag characteristics, the filtration rate, the dust concentration, the cleaning method, the flue gas temperature and the flue gas viscosity. The bag dust collector resistance Δp is composed of the structural resistance Δpc, the cleaning bag resistance Δpf and the accumulated dust layer resistance Δpd on the filter bag: Δp = Δpc + Δpf + Δpd (1) Δpc refers to the dust collector inlet, outlet and air flow distribution device, Plate, etc., usually Δpc <300 Pa. (2) where: ξf is the filter bag resistance coefficient, m-1; μ is the viscosity of the gas, Pa · s; υ is the filtration wind speed, m / s. The filter bag resistance Δpf is: Δpf = ξ fμυ (2) Generally Δpf <300Pa, dust layer resistance Δpd and filter bag, dust particle size distribution, chemical composition, flue gas temperature, moisture content and other factors, to be determined by experiment. The resistance of the dust layer increases with the increase of the dust deposition thickness at the same filtration rate. When the filtration rate is less than 0.5m / min, the thickness of the dust layer is independent of the resistance. When the filtration rate is less than 1.2m / min and greater than 0.5m / min, the thickness of the dust layer increases to a certain extent, and the resistance of the dust layer is increased linearly. The increase in resistance of the bag filter can improve the filtration efficiency, but the increase of the running resistance will increase the energy consumption. Therefore, there is the best balance between the resistance of the bag filter and the filtration efficiency. It is suggested that the resistance of the bag filter should be controlled between 1200 and 1500Pa.Third, the dust particle size on the filtration efficiencyFlue dust particle size directly affects the filter efficiency of bag filter. Dust particle size in different conditions of the classification efficiency shown in Figure 3.It can be seen from Fig. 3 that the filtration efficiency increases with the increase of particle size, but the dust with particle size of 0.2 ~ 0.4μm has the lowest filtration efficiency under different filter bag conditions. Compared with the filter bag after cleaning and cleaning, the filtration efficiency of the filter bag is the lowest, and the filtration efficiency is mainly dependent on the filter bag, the filter bag surface dust filter efficiency, especially for the particle size of less than 0.5μm dust filtration efficiency Improve significantly.
Fourth, dust pretreatmentDust pretreatment mainly by reducing the dust concentration, change the dust particle size distribution, in order to reduce the filter bag dust load, thereby reducing the number of cleaning, to extend the life of the filter bag. It is possible to reduce the dust concentration by setting the electrostatic precipitator, the cyclone type dust collector, the blinds, the humidifying tower, etc. before the bag filter. Changing the particle size distribution of dust is an important way to solve the problem of superfine dust collection, that is, through the coagulation and condensation, chemical condensation and the way the small dust into a larger particle dust for the use of collection.