Types and working principles of dust collectors for coal-fired boilers11/30/2021
The maintenance and maintenance of coal-fired boilers are inseparable from dust collectors. At present, there are many types of dust collectors for coal-fired boilers. The following introduces the types and working principles of dust collectors for coal-fired boilers.
One, Mechanical dust collector
Mechanical dust collector is a device that uses mass forces (such as gravity, inertial force and centrifugal force) to separate dust particles from airflow. Such as gravity dust collector, inertial dust collector and cyclone dust collector. The mechanical dust collector is characterized by its simple structure, low cost and convenient maintenance, but its dust removal efficiency is low.
Both the gravity dust collector and the inertial force dust collector have low dust removal efficiency and cannot meet the current environmental protection requirements, so they are gradually being eliminated. Although the dust removal efficiency of the cyclone dust collector is higher than that of the first two, because the flue gas resistance is large and it is difficult to separate dust particles with a particle size of less than 5 tim, it is not suitable to use the pulverized coal furnace, and the chain furnace is more used.
Two, filter dust collector
The filter type dust collector is a device that separates and traps dust by passing the dust-containing air flow through the filter material. Such as particle layer dust collector, bag dust collector, etc. The filter dust collector has the advantages of high dust removal efficiency (high dust removal efficiency under low dust concentration), simple operation, reliable operation, etc., but it has large resistance and high energy consumption, and is not suitable for processing wet gas and viscous dust.
Due to the relatively large investment in filter type dust collectors, large resistance and high operating costs, they are currently less used in boilers.
Three, wet dust collector
Wet dust collectors use dust-laden airflow in contact with water or other liquids to trap dust particles. Such as venturi dust collector, cyclone water film dust collector and so on. The scrubber dust collector has high efficiency, simple structure, low cost, and also has the function of absorbing harmful gases, but it will produce sewage and sludge, which needs to be treated.
This kind of wet dust collector has simple structure, less metal consumption and less area, so the dust removal efficiency can reach more than 90%, so medium and small boilers are used more. The disadvantage of the wet dust collector is that it consumes a lot of water, and the acid-containing wastewater needs to be treated to meet the discharge standard. The water in the flue gas causes the flue and the induced draft fan impeller to accumulate dust, causing corrosion and the unbalanced quality of the induced draft fan impeller and vibration.
Four, electric precipitator
The electrostatic precipitator is a device that uses a strong electric field corona discharge to ionize the gas, charge the dust particles, and separate the dust particles from the airflow under the action of Coulomb force. The electrostatic precipitator is characterized by high dust removal efficiency, high temperature gas processing, low resistance, low operating cost, but large steel consumption, high cost, and high technical requirements.
Because the electrostatic precipitator has large flue gas processing capacity, low resistance, and good adaptability to soot concentration, it can collect dust particles of various sizes, and the dust removal efficiency is as high as 95%. The operating cost is lower and the environmental protection emission standard is improved. It can meet the requirements of the improved new environmental emission standards. Therefore, although the initial investment is high, the area is large, and the manufacturing, installation, and maintenance quality requirements are high, most of the large and medium-sized pulverized coal furnaces use electric precipitators.
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