dust filtration system

General concept of dust

Dust is particulate matter in the air (atmospheric particulate matter, particulate matter, PM). According to the dust size, it is divided into different types: PM 10 (from 2.5 to 10 micrometers), PM 2.5 (under 2.5 micrometers), PM 1.0 (under 1 micrometer) and PM 0.1 (less than 0.1 micrometers). ) is also known as nanometer dust, NANO dust.

Part of these small fine dust particles can be generated from nature, but most of them are due to human activities and activities. In nature, airborne dust is created from volcanic smoke, forest fires, dust storms, tornadoes, biological products or wastes such as pollen, fungal spores, insect wastewater, etc. dust pollution in the air through burning charcoal, burning fossil fuels, dust from construction sites, street dust, burning garbage, industrial machine smoke, deforestation, smoking...

Dust treatment methods

Dust treatment by dry method

	Dust treatment by dust settling chamber	Dust treatment with centrifugal dust collector	Dust treatment with filter dust filter equipment (cloth bag, dust filter net)	Dust treatment by electrostatic precipitator
Structure	Dust settling chamber; a) Longitudinal section; b) Spatial diagram.	Standing Cyclone 1. Air and dust inlet duct 2. Body of the device 3. Con 4. Dust exhaust pipe 5. Clean air outlet 6a,6b. Dust release valve	Dust filter net Cloth bag dust collector
Working principle	Based on the basis of gravity to settle particles of relatively large size by reducing the velocity of gas and dust when entering the settling chamber, dust particles have mass (with gravity P), so when the velocity decreases Dust particles will separate from the gas stream and settle. Clean air is brought out.	Gas and dust are introduced in a tangent to the wall of the vessel (outer cylindrical surface) and vortex moves from top to bottom. Dust of mass m, according to inertia, hits the wall of the vessel, so it loses kinetic energy and falls down. The clean air changes direction and follows the small cylinder inside to move up and out.	Air and dust flow is blocked by membrane or filter bag; This bag (membrane) has small slits (holes) for gas molecules to pass through easily but traps dust particles. When the dust layer is thick enough to prevent the passage of air, it is vibrated or blown back to collect dust and clean the membrane.	Gas and dust are introduced into the device. Under the high voltage that the metal wire is charged, it will create a strong electric field inside the anode tube, and when the dust-carrying gas flows through, the gas molecules in the gas stream will be ionized and then transfer a negative charge to the electrode. dust particles under the effects of inertial impact and ion diffusion. As a result, dust particles are attracted to the anode, deposited on the inner surface of the cylindrical tube, losing their charge and falling into the dust hopper. Clean air follows the gas pipeline to the outside.
Efficiency	+ Low dust filtration efficiency: µ= 40-60%, applied to settle coarse dust with large particle size from (60 - 70µm). + Usually used at the pre-filter level or where the environmental conditions are not strict	Dust filtration efficiency reaches: µ = 60 – 80%. Filters out medium and relatively large dust	+ Very high dust filtration efficiency: µ = 80-90% (dust filter mesh); µ = 90-95% (cloth bag style) + Filters dust particles from small to large. + When the concentration of dust is too large, the dust collects a lot, the equipment must be cleaned regularly	+ Equipment using direct current with U = 30 - 70 kV + High efficiency: µ = 95 – 99%.
Advantages	♦ Initial investment, low operating costs ♦Simple texture ♦ Used in the treatment of gas with high dust concentration containing large dust particles, especially from the metallurgical industry, metal smelting. ♦ Low pressure loss through the device. ♦ Air velocity in the equipment is low, so it does not cause equipment wear. ♦ Contribute to the cooling of the air stream before being discharged into the environment or passed through the next dust collector.	♦ Gas and dust go in opposite directions, so the treatment efficiency is high. ♦ Simple manufacturing, easy operation, can repair and replace each part. ♦ Can work at high temperature (up to 500oC), work well at high pressure ♦ Efficiency is independent of dust concentration variation. Takes up little installation space, so it is often used in practice	♦ High dust filtration efficiency ♦ Filters dust particles from small to large. ♦ Save costs when choosing materials to make up bags and nets. ♦ Lubricating oil helps the dust filter to increase dust filtration efficiency.	♦ Filter all kinds of dust from large size to small size.
Defect	♦ Must be manually cleaned periodically. ♦ Bulky, takes up space, requires a large space when installing. ♦ Only relatively large dust particles can be obtained ♦ Wet and sticky dust cannot be collected.	♦ Poor treatment efficiency for dust less than 5 µm in size. ♦ The resistance of the gas flow is large, so the engine must be large, so the operating cost is high. ♦ It is not possible to collect sticky dust.	♦ Dust entering the device must be dry dust (for cloth bags) ♦ Must clean the device regularly	♦ Expensive price ♦ Requires dust entering the device to be dry.