In the design of the dust collector of asphalt mixing station, the pulse back-blowing dust cleaning method with good dust cleaning effect is adopted, which has simple structure and convenient operation and maintenance. Huiyang technicians specially choose imported high-temperature dust removal bag to make the dust concentration discharged into the atmosphere less than 3mg/Nm3, which fully meets the requirements of environmental protection.
Characteristics of asphalt mixing station flue gas:
1. Small particle size: asphalt flue gas mainly exists in the form of tar fine fog particles of .1 ~ 1. μ m, and the smallest is only .1 μ m;
2. The temperature of asphalt flue gas is generally higher than 1℃; There are hidden dangers such as fire and explosion.
characteristics of the dust collector bag of asphalt mixing station:
temperature resistance: it can be operated continuously at the temperature of 24℃ (instantaneous temperature is 25℃) and can withstand repeated instantaneous fluctuating temperature of 25℃.
stability: the thermal shrinkage is less than 1% at 25℃, and it has high temperature stability.
fire resistance: decomposition and carbonization only begin at 4℃, and the limiting oxygen index (LOI) is 3, so it does not spontaneously ignite or support combustion.
chemistry: low concentration of acid and alkali and most hydrocarbons will not affect it, even a small amount of fluoride will not corrode obviously;
The flue gas discharged from asphalt mixing station is purified by Huiyang bag dust collector after dust and smoke are removed. There are eight commonly used purification methods for asphalt flue gas:?
1. mechanical separation method: when the asphalt flue gas contains dust, steam or water mist is sprayed into it to increase the particle diameter of the flue gas, and then the gas is separated from the particles in a settling chamber or cyclone, so as to purify the asphalt flue gas. Because the particle size of dust is too small, even if it is increased by colliding with each other, it still can't reach the suitable particle size of cyclone dust collection, and the dust collection effect is very poor, so the mechanical separation method is rarely used. ?
2. condensation method: as an auxiliary method, condensation method is used to purify asphalt flue gas, which is used in conjunction with other purification methods (such as adsorption, absorption, etc.). By condensation, asphalt flue gas can increase the particle size of fog particles in flue gas, which is beneficial to purify asphalt flue gas. ?
3. absorption purification method: absorption purification method, commonly known as washing method, is a commonly used industrial waste gas treatment method. The absorption purification method is applied to the treatment of asphalt flue gas, which is to transfer the gaseous pollutants (actually .1 ~ 1. μ m tar fine fog particles) in the flue gas to the liquid state (absorbent), so as to achieve the purpose of purifying the flue gas. Water is the most economical and effective absorbent for treating a relatively small amount of asphalt flue gas after dry bag dust removal in asphalt concrete mixing station. After being absorbed by water, tar fine particles in asphalt flue gas are basically insoluble in water, and will not react to produce a large number of new compounds. Most of them form oil slick floating on the water surface, which can be collected to a certain extent and then mixed into coal as fuel. After many cycles, the concentration of emulsion in water will increase, which will reduce the treatment effect. ?
4. filtration method: filtration method is a method that uses porous media to collide with tar fine mist particles in asphalt flue gas to adsorb tar fine mist particles in flue gas, thus purifying asphalt flue gas. In principle, it should belong to the adsorption method, which has been used in the domestic waterproof industry for more than 1 years and is also the most widely used asphalt flue gas treatment method at present. Bag filter is one of the commonly used methods, but it needs oil-proof, waterproof, heat-resistant and corrosion-resistant filter bags for asphalt flue gas purification. Although it has high purification efficiency, it can't filter dust below .5 micron. ?
5. adsorption purification method: adsorption purification used for asphalt flue gas treatment is physical adsorption, which is caused by intermolecular attraction, usually called "Van der Waals force", which is the general name of directional force, induced force and dispersion force. Its characteristic is that there is no chemical interaction between adsorbent and adsorbate, which is a reversible process, namely adsorption and desorption. Physical adsorption is generally not affected by temperature, but the adsorption capacity decreases with the increase of temperature. Therefore, condensation treatment of asphalt flue gas before adsorption purification can improve the purification effect, and selecting suitable adsorption filter material is one of the keys of adsorption purification method. ?
6. Electrostatic capture method: Because the specific resistance of asphalt is appropriate, it has no corrosive effect on metals. After being captured, it is liquid. Electrostatic capture method has a good effect on purifying asphalt flue gas. ?
7. combustion method: the asphalt flue gas is directly introduced into a special heating furnace for incineration, and after a certain period of high temperature incineration, the asphalt flue gas can be completely purified. This therapy is often used in tail gas treatment of asphalt oxidation plant, but this method has large equipment investment, high operating cost and great security risks. ?
8. Low-temperature plasma dust removal technology: As an efficient and new dust removal technology, low-temperature plasma technology has realized the integration of dust removal, desulfurization and denitrification. The purification rate of smoke and dust can reach 98%, and the removal rate of VOCs of organic volatiles is ≥ 85%, and ultrafine dust particles of .1 ~ .1 μ m can be collected.