Dust collector or dust removal equipment is a kind of equipment that separates dust from flue gas. According to the principle of action, commonly used dust collectors can be divided into four categories:
1. Mechanical dust collector
Mainly refers to the dust removal equipment designed by the application of dust inertia and gravity, such as gravity dust collector, inertial dust collector and cyclone dust collector. It is mainly used for the separation or concentration of high-concentration coarse particle diameter dust.
2.Bag type dust collector
The filter is a dust removal device with a fiber woven fabric or a filling layer as a filter medium. It has a wide range of uses, forms, dust removal air volume scale, and efficiency. It is mainly used in places to capture fine dust. Exhaust dust removal system is applied to the air intake system. In recent years, due to the continuous development of new filter materials, the development of fiber filtration technology has also accelerated, new products are constantly appearing, and the application field has been expanding.
3.Wet dust collector
Dust removal devices that rely on hydrophilicity to separate and capture dust particles, such as spray towers, scrubbers, impact dust collectors, venturi tubes, etc., are used to deal with high-concentration, high-volume dust-containing gases that occur during production Adopt more. The separation efficiency of coarser, hydrophilic dust is higher than that of dry mechanical dust collector.
4.Electric dust collector
The dust collector introduces the dust-containing airflow into the electrostatic field. Under the action of the high-voltage electric field, the gas is ionized to generate electrons and positive ions. They move to the positive and negative poles respectively. When the dust particles flow through the working electric field, they are negatively charged. At a certain speed, they are moved to the settling plates with the opposite sign to their negative charge, and settle down there, so as to get out of the airflow and be collected in the electrostatic precipitator.
Cyclone Dust Collector
Wet Dust Collector
Selection of dust collector
1. Selection according to the amount of processing gas:
The amount of processing gas is the decisive factor for the size and type of the dust collector. For the atmospheric volume, it is necessary to choose a dust collector that can handle large gas volumes. If multiple dust collectors with small gas volumes are used in parallel, it is often uneconomical. For small air volume, it is necessary to compare which type of dust collector is the most economical and the easiest to meet the dust source control and dust emission environmental protection requirements.
After the dust collector enters actual operation, it is sometimes difficult to predict the impact of operation and environmental conditions. Therefore, when determining the capacity of the equipment, you must ensure a certain margin or reserve some space that may increase the equipment.
2. Select according to the dispersion and density of dust:
The degree of dust dispersion has a great impact on the performance of the dust collector, and the degree of dust dispersion is the same, due to different operating conditions. Therefore, when selecting a dust collector, the first step is to accurately grasp the dispersion degree of the dust. If the particle size is more than 10 μm, a cyclone dust collector can be selected. If the particle size is more than a few microns, a bag dust collector should be used. ,Electrostatic precipitators.
Dust density also has a great impact on the dust removal performance of the dust collector. The most obvious manifestations of this effect are gravity, inertial and centrifugal precipitators. A common feature of all dust collectors is that the smaller the bulk density, the more difficult the separation and collection of dust particles, and the more serious the secondary fly of dust, so special measures should be taken in operation and equipment structure.
3. Select by gas dust concentration:
For gravity, inertial force, and cyclone dust collector, the larger the dust concentration at the inlet, the higher the dust removal efficiency. However, this will increase the dust concentration at the outlet, so we cannot generally assume that the dust treatment effect is good based on the high dust removal efficiency. For wet-type dust collectors such as Venturi dust collectors and jet scrubbers, the initial dust concentration is preferably below 10g / m³; for bag dust collectors, the lower the dust concentration, the better the dust removal performance. At higher initial concentrations, continuous ash cleaning, pressure loss and discharge concentration can also meet environmental protection requirements. The initial concentration of electrostatic precipitator is below 30g / m³, which can also be used without pre-precipitator.
4. The influence of dust adhesion on selection:
The adhesion mechanism of dust and wall has a great relationship with the specific surface area and moisture content of dust. The smaller the dust particle size d, the larger the specific surface area, the greater the water content, and the greater its adhesion.
In the cyclone dust collector, the dust adheres to the wall due to centrifugal force, and there is a danger of clogging. The dust adhered to the bag dust collector can easily block the holes of the filter bag; the electric dust collector easily causes the discharge electrode and the dust collector to collect dust .
5. The influence of dust specific resistance on selection:
The dust resistance of the electrostatic precipitator should be in the range of 104 ~ 10nΩ · cm. The specific resistance of dust varies greatly with the temperature and humidity of the dust-containing gas. For the same kind of dust, the specific resistance value is greater between 100 and 200 ° C; if the dust-containing gas is sulfurized and tempered, the specific resistance is reduced. Therefore, when selecting an electrostatic precipitator, it is necessary to grasp the specific resistance of the dust in advance, and fully consider the choice of the temperature of the dust-containing gas and the adjustment of the properties of the dust-containing gas.
6. The influence of dust-containing gas temperature on selection:
Dry dust collectors must, in principle, be operated at temperatures above the dew point of the dust-containing gas. In wet dust collectors, due to water evaporation and condensation after being discharged to the atmosphere, it should be treated at as low a temperature as possible. In the filter cartridge dust collector, the temperature for directly or indirectly handling the dust-containing gas should be lower than the heat resistance temperature of the filter cloth. The operating temperature of glass fiber filter cloth is generally below 260 ° C. Other filter cloths are between 80 ~ 200 ℃. In the electrostatic precipitator, the use temperature can reach 400 ℃. It is necessary to consider the specific resistance of dust and the thermal expansion of the dust collector structure to select the temperature for processing the dust-containing gas.
7. Precautions for selecting wet dust collector:
Wet dust collectors are mostly water-based. If the size of the dust source equipment is small, it is necessary to remove harmful gases at the same time, or when it is necessary to completely capture extremely fine carbon black, lead dust and other dust, wet dust collectors are often used. Sewage treatment should be considered in the selection of wet dust collectors to prevent secondary pollution.
This system mainly includes dust processing system, power system, exhaust emission system, automatic control system, etc. Among them, the dust treatment system can be selected according to actual needs, such as bag dust collectors, filter cartridge dust collectors, wet dust collectors and other process equipment.
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2. Sale service
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