Design and selection of pulse bag type dust collectors first need to understand the dust-containing gas conditions (including treatment volume, temperature, humidity, dust concentration, dust properties, etc.) that need to be treated by the dust collector, and then design and select the dust collector, piping system and auxiliary equipment. As with other dedusting equipment, there are several issues to consider when designing and selecting a bag filter.
1. In the absence of design experience, 75 x 9.8 Pa can be used as typical data at low filtration speeds. However, if a higher filtration speed is adopted, or if there is a sticky or low porosity dust layer, a slightly higher value should be taken.
2. Filtration speed is an important factor in determining the performance of a baghouse. If the filtration speed is too high, the pressure loss will be too large, the dust removal efficiency will be reduced, and the dust filter bag will be blocked and prematurely damaged. However, increasing the filtration speed can reduce the filtration area required for the baghouse, so that a smaller dust removal device can be used to process the same volume of gas.
There is an optimum filtration speed for a certain set of design parameters (ie, dust collector type, cleaning mechanism, dust bag material and fabric structure, dust properties, etc.). Generally, fine dust takes a lower filtration rate than coarse dust, and smaller dust collectors tend to use higher filtration speeds than large dust collectors. Pulsed, reverse jet filters can achieve higher filtration speeds than vibrating and reverse airflow.
For vibrating and reverse airflow precipitators, for general dust, the filtration speed can be 0.9m/min. From the perspective of both investment and maintenance, it is recommended that the feed filtration rate of feed and grain dust and flour can be 0.98 and 0.75 m/min, respectively.
3. The gas flow rate (m3/min) divided by the filtration speed (m/min) gives the actual required fabric area (m2). Due to temperature changes and additional increases and decreases in air, the volume of dust-laden gas entering the dust collector is not necessarily the same as the volume discharged from the production process. If the dust collector is used in a situation where the flow rate changes, it is necessary to make a judgment as to whether the filtration area is calculated according to the peak flow rate or the average flow rate. In addition, the reserve of the duster bag fabric should be considered for cleaning, inspection and maintenance.
4. How many compartments are needed for a bag filter is easier to determine. After determining the area of the dust bag in each compartment, the most advantageous dust filter bag length, diameter and spacing are determined. The general length dust filter bag preferably has a pitch of not less than 50 mm. Extra long (eg more than 3 meters) dust filter bag spacing should be larger. The dust filter bags should be grouped to leave a passage between the two groups. If there is a passage on only one side, the dust bag is 150 mm in diameter and each group should not be more than three or four rows of filter bags. There should be no more than two rows per group with a diameter of 300 mm. If there are channels on both sides, there should be no more than eight rows with a diameter of 150 mm and no more than four rows with a diameter of 300 mm. The channel width is 450 to 600 mm. The total number of dust filter bags per set depends on the vibration mechanism used. Typically, a set of filter bags is internally operated by a set of vibrating mechanisms. A compartment can contain several sets of filter bags.