Exhaust gas treatment is currently an environmental issue of concern. The causes and consequences of emissions have been mentioned by Nanoen in the article “Alarm! The time bomb called "Air", one of the sources of emissions mentioned is industrial emissions. So, the question for us is “To reduce the concentration of pollution emitted into the air, what technologies can be applied in the production process of enterprises?”. The answer will be in the article below.
1. WHAT ARE EMISSIONS?
Emissions are a combination of toxic gases that are in gaseous form and released into the outside environment. Emissions occur in industrial zones, in agricultural production activities, and also occur during the combustion of fuel in vehicles, etc. The three types of emissions that appear frequently in the air are CFCS, NOX, and CO2.
Currently, there are many causes of emissions in the environment. But those causes all occur around our lives. To learn more about the causes and consequences of air pollution caused by toxic emissions, please refer to the article "Alarm! The time bomb called "Air""
The causes and consequences of air pollution have been and are at an alarming level, constantly affecting our lives and health. Here are some dust and exhaust gas treatment methods that Nanoen has compiled, please refer to them!
2. SOME TYPICAL DUST TREATMENT METHODS
2.1 Dry dust filtration method includes:
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Dust separation cyclone:
Operates on the principle of losing the inertia of particles.
The air carrying dust enters the treatment tower in a tangential direction and goes from top to bottom. Thanks to the tangentially installed air duct, the air will move in a spiral inside the cylindrical body of the cyclone. In the vortex flow, the dust particles are affected by centrifugal force, causing them to tend to move towards the tower body and then touch the tower body, losing kinetic energy and falling to the bottom of the funnel. The clean air flow will escape upwards and out.
Reference image: Cyclone
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Dust filter bag (fabric bag dust filter):
With a simple operating principle, the dusty air stream will be brought into the fabric bag dust filter system. These filter bags are made of materials such as fabric, twisted fibers, cardboard made of cellulose-asbestos mixed fibers, etc. When the dusty air stream is brought into the system, the dust will be retained by these filter bags, clean air will go through the upper pores of the filter bag into the bag and escape. Dust on the surface of the filter bag will be collected by the dust shaking system and returned to the dust collection hopper.
Reference image: Fabric bag dust filter
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Electrostatic dust collector:
Electrostatic precipitator is a system that removes ultra-small dust particles (0.01 − 10 µm). Based on the principle of ionization and separation of all dust from the air when they pass through a large electric field. In the two-zone dust collector, a 220V power source is supplied to the current settling unit and the voltage is increased to create a DC power source with a voltage of 13 and 6.5kV connected to the positive electrodes by thin steel wires placed about 30mm apart in the ionization zone. At a certain voltage, gas or air molecules are ionized at the charged electrode and divided into positive and negative ions. The gas ions with the (+) sign will move towards the negative pole and on the way they collide with the dust particles, causing the dust particles to be positively charged, thereby attracting the dust to the dust collecting electrodes.
The dust collection area consists of alternating positive and negative electrodes in the form of plates placed 10mm apart, the negative electrode is grounded and the positive electrode is connected to a 6.5kV power source. Dust will adhere to the surface of the electrode plates and will be brought down to the dust collection hopper by periodic shaking. The clean air will rise and escape.
Reference image: Electrostatic dust collector
2.2 Wet dust filtration methods include:
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Spray chamber - empty gas washing tank:
Spray chamber or empty gas washing tank is very commonly used to filter coarse dust in exhaust gas, at the same time to cool the gas as a preparatory filter level and "process" the dust before the electric filter to reduce the initial dust concentration and adjust the resistivity of the dust.
Hollow Absorber Tower (Hollow Tower)
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Watered Hollow Material Dust Collector:
Watered Hollow Material Dust Collector, also known as Gas Scrubber (Tower) consists of a circular or rectangular electric tank containing a layer of hollow material and watered. The gas flows from bottom to top through the hollow material layer, when in contact with the wet surface of the hollow material layer, it will stick there and clean gas will escape. Part of the dust is washed away by water into the tank and discharged as a sludge blanket.
Scrubber gas scrubber tower
3. SOME TYPICAL EXHAUST GAS TREATMENT METHODS
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Exhaust gas treatment by adsorption method:
The adsorption process is carried out by contacting two incomplete phases, the solid phase (adsorbent) with the gas phase. The solvent (adsorbent) will go from the gas phase to the solid phase until the concentration of the molecule distributed between the two phases reaches equilibrium.
There are two types of adsorption: physical adsorption and chemical adsorption.
+ Physical adsorption: is the phenomenon of reversible interaction of the attraction forces between the molecules of the solid and the adsorbed substance.
+ Chemical adsorption: is the result of the chemical interaction between the solid and the adsorbed substance.
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Exhaust gas treatment by adsorption method:
Absorption is based on the mass transfer process, that is, the separation of two phases. Depending on the interaction between the absorbent and the adsorbed substance in the gas phase, the absorption method is divided into: physical absorption and chemical absorption. Physical absorption is based on the dissolution of gas phase components in the liquid phase. Chemical absorption occurs between the adsorbed substance and the absorbent or the component in the liquid phase.
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Biological treatment Biofilter:
Is an odor treatment method for wastewater treatment systems with low investment and operating costs and is environmentally friendly, suitable for treating odorous gases and low concentrations of volatile organic compounds. Biofilters are often used in factories producing animal feed, livestock, cassava starch, alcohol production, chitin production, landfill gas emissions, odor treatment of wastewater treatment systems...
Read more: Air Stripping Tower
A unit that provides businesses with methods of treating exhaust gas according to their needs
Usually, choosing a method of treating exhaust gas is a very important task, affecting the usage process, investment capital as well as treatment efficiency. Exhaust gas treatment is a necessary task for businesses to contribute to protecting the environment and people, towards sustainable development. Depending on the production characteristics of each factory, the exhaust gas released into the environment has different components and properties, so the treatment process requires people with high expertise and techniques to perform.
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With a team of experienced staff, we have a full range of services from environmental profile consulting to construction design, environmental treatment system operation, re-operation and supply of microorganisms, etc.
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