Parameters of bag filter model

Parameters of bag filter model
The main technical parameters for the design, production, and selection of bag filters are widely applicable, including mechanical equipment, workshop grinding, power plants, steel plants, cement plants, chemical plants, smelting, carbon, casting, and other factories. There are many types of bag filters, therefore, their selection calculation is particularly important. Improper selection, such as equipment being too large, can cause unnecessary waste; Choosing small equipment can affect production and make it difficult to meet environmental requirements. choose
Choosing the correct bag filter can better achieve dust removal effect and solve smoke pollution.
The main technical parameters for the design, production, and selection of bag filters include gas flow rate, filtration wind speed, and dust removal
Efficiency, imported dust concentration, emission concentration, number of filter bag specifications, number of dust removal framework specifications, electromagnetic pulse valve
Specification and quantity, pressure loss, air leakage rate, steel consumption, specification and model of induced draft fan, length and width of dust collector, etc.
1. The processing gas flow rate, also known as the processing air volume, is generally expressed as the flow rate per unit volume, in m3/h. The processing air volume generally refers to the amount of gas that the dust removal equipment can purify within a certain period of time (expressed in volume). It is one of the factors in the design of bag filters. When designing or selecting a bag filter based on air volume,
Generally, it is not allowed to operate the dust collector beyond the specified air volume, otherwise the filter bag may easily block and shorten its lifespan
Short, pressure loss significantly increases, and dust removal efficiency also needs to be reduced; But the air volume cannot be too large, otherwise it will increase equipment investment and land occupation. The selection of processing air volume is often determined based on process conditions and experience.
2. Dust removal efficiency. Refers to the amount of dust captured and collected at the same time when the dusty airflow passes through the dust collector
The ratio of the amount of dust entering the dust collector, expressed as a percentage. Dust removal efficiency is an important technical indicator of dust collectors. Almost all
Some industrial bag filters can achieve a dust removal efficiency of 99% or more, but the dust removal method is
The design is different. The dust removal method is crucial, as it not only affects the size and cost of the bag filter,
It is more related to the use, maintenance, and online operation of the dust collector.
The commonly used bag filters in industry include mechanical vibration, reverse airflow reverse blowing, and pulse jet bag filters. Vibration
And reverse blowing ash cleaning is the ash cleaning method used in bag dust collectors. When cleaning the dust in the filter room, the air door is used to isolate the smoke for 2-5 minutes. The reverse blowing of dust causes less bending of the cloth bag, so the service life of the cloth bag is longer. Filter cloth powder per unit area
The dust capacity ranges from 0.1 to 1.0kg/m2, depending on the properties of the dust and filter bag. The filtering wind speed of the reverse blowing bag filter is generally within the range of 0.5-2m/min. For mechanical vibration bag filters, the residual amount of dust on the filter bag is related to the frequency and intensity of vibration.
When selecting a dust collector, it is generally not necessary to calculate the dust removal efficiency. The main factors affecting dust removal efficiency are as follows
Surface: Operating parameters, including filtration speed, resistance, gas temperature, humidity, cleaning frequency, and intensity; Ash cleaning methods include mechanical vibration, reverse airflow, compressed air pulse, and air ring. The properties of dust, including the particle size, inertia force, shape, static charge, moisture content, etc. of the filtered dust. For filter dust collectors with external electrostatic fields, the specific resistance of the dust should also be considered; Fabric properties, including the thickness of fabric raw materials, fibers, and yarns, weaving and felting methods, fabric thickness, porosity, etc; There are two main reasons for the increase in dust transmittance:
① Direct through mechanism, in filtration, dust passes through without being obstructed. When dust particles pass through, they may follow a winding path or directly pass through the needle holes on the surface of the filter material. Generally, high filtration speed can increase the direct through amount of the needle holes;
② The leakage mechanism is that the dust initially trapped by the filter material becomes loose after cleaning and is blown through the filter bag; Or when filtering resistance occurs, some dust that has already been trapped is squeezed past. Some dust leaks out from the pinholes. Leakage may worsen at high filtration rates or when the fabric is subjected to vibration.
3. Pulse injection parameters: injection pressure, injection cycle, and injection time are the three elements of pulse bag dust collector injection.
4. The filtration wind speed and filtration speed are important factors in the design and selection of bag filters. Its definition is the speed at which the filtered gas passes through the filter material, or the ratio of the air volume passing through the filter material to the filter material area. The unit is expressed in m/min. If the filtering area of the bag filter is determined, the size of its processing air volume depends on the selection of filtering speed, and the formula is:
Q = v  ×  s  ×  60   (m3/h)
In the formula: Q - processing air volume v - filtration air speed (m/min) s - total filtration area (m2)
Note: Filtering area (m2)=Processing air volume (m3/h)/(Filtering speed (m/min) x 60)
5. Imported dust concentration can be used to treat gases with high dust concentration. Cyclone dust collectors or gravity dust removal equipment can be installed as pre dust removal, but this will increase the resistance of the system and power consumption. So when dust or finished materials do not need to be classified, bag type dust removal equipment is mostly used directly. Not all bag dust removal equipment can handle gases with high dust concentrations. Only bag type dust removal equipment with a wide spacing between filter bags and a continuous dust removal device installed outside the bag is suitable for handling gases with high dust concentration. When dealing with high dust content, the structure should try to prevent dust from directly falling into the ash hopper or adding some baffles to reduce the amount of dust attached to the filter bag; To prevent friction damage to the filter cloth, high-speed dust should not directly impact the filter cloth. The middle part of the box can also serve as a pre dust collector, and also serve as a power settling chamber for dust and a diversion chamber for inlet gas. The bag type dust collector used for collecting dust in pneumatic conveying devices, although it processes less air volume, has high dust concentration, and the box requires pressure resistance, it is more cylindrical in shape. Enterprises with conditions can replace bag type dust collectors with plastic fired plate dust collectors.
The entrance of the cylindrical box is made in a tangent direction, which has a separation effect. Many rotary back blowing bag filters are in this form. Sometimes the ash hopper is made into a cyclone dust collector. The bag type dust collector of the pneumatic conveying system needs to be designed with a larger volume and diameter of the ash discharge port due to the large amount of powder, and the capacity of the dust discharge device should also be left with sufficient space to avoid the retention of powder in the ash hopper.
6. Emission concentration refers to the concentration of gas emitted from the net gas outlet. This is a performance indicator for measuring the dust removal efficiency of dust collectors. The emission concentration of bag dust collectors is generally carried out according to national environmental standards, and now it is generally below 30mg/m3.
7. The specifications and quantity of filter bags are determined by the filtration area of the bag filter. As long as one bag of the bag filter is damaged or leaked, it will lead to a decrease in the dust removal efficiency of the entire dust removal system. Therefore, a good design of a bag filter depends on whether it can be easily accessed for maintenance and quickly replaced with damaged bags