01
Mar

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Asphalt smoke -- prevention and control measures of pollutants in asphalt mixing equipment

Is there any pungent smell at the production site of your asphalt mixing plant? In the mixing plant fueled by natural gas, asphalt smoke, as the main air pollution emission, is closely related to the prevention and control measures taken by the production equipment. How to prevent and treat the asphalt flue gas produced in the production process of asphalt mixing plant? There are several ways to solve this problem.

Incineration treatment

The asphalt smoke is led from the finished product warehouse to the burner. The induced draft system sucks the asphalt smoke into the flame of the burner. The collected flue gas is ejected from the annular air duct of the burner and enters the air duct evenly at the flame in the drying drum.

The most effective collection method at the discharge port is to set a channel with rolling shutter door at the discharge port. By installing control components at the discharge port, the asphalt flue gas is collected through the adjustment and control of the wind deflector.

Adsorption collection

1. Static electricity

The asphalt smoke passes through the primary channel. The asphalt smoke particles are ionized by the high-voltage DC electrode and carry negative charges. After entering the secondary channel, the hydrocarbon particles are adsorbed by the positive electrode and separated from the gas flow, and the treated gas flow is directly discharged into the atmosphere. The electrode of electrostatic precipitator shall be cleaned regularly to eliminate particle accumulation.

2. Media filtration

After the asphalt smoke is sucked into the filtration system, part of the smoke is condensed into the storage tank first, and the remaining smoke enters the secondary filter. The first stage preliminarily filters condensate droplets, the second stage oil mist filter plays the role of asphalt smoke filtration, and the filtered flue gas is discharged into the atmosphere by fan. It is usually used to collect smoke particles and is not suitable for fine particles with high concentration. In order to ensure the normal operation of the adsorption device, the filter core needs to be replaced frequently.

3. Powder wrapped smoke

Similar to the bag type dust collector, the powder wrapped smoke filtering device is to add fiber materials into the asphalt smoke pipeline to fully mix it with the asphalt smoke, and then remove it by the bag type dust collector. The powder wrapped smoke filter adopts three filtering methods: impact, interception and Brownian diffusion. Impact refers to the collision between asphalt smoke particles and filter screen, which is more than 3 times μ M is effective; Interception is used to collect 1-3 μ Small particles within m; Brownian diffusion is used to collect submicron particles. The principle is: under the action of air flow, submicron particles generate Brownian motion such as rotation and translation along the arc track, collide with the filter fiber and are collected, so as to be removed from the air flow. The method of powder wrapped smoke requires regular replacement of the filter screen to meet the differential pressure requirements of the dust collector.

Low temperature plasma flue gas purification method

In the low-temperature plasma asphalt flue gas purification technology, there are three principles and functions: high-voltage pulse high-energy electron radiation, ultraviolet decomposition and ozone oxidation. This technology can well destroy the macromolecular structure in asphalt flue gas and generate small molecular substances. Under the action of ozone, the plasma collides with the molecules in the asphalt flue gas, so that the high-energy electrons generated in the plasma structure are excited to a higher energy level state to form excited molecules, which breaks the chemical bond of the internal structure of hydrocarbons to form active substances, and the final products are CO2 and H2O.

UV photocatalytic oxidation purification

UV photocatalytic oxidation purification method has strong molecular decomposition ability for asphalt flue gas, and can effectively remove volatile organic compounds (VOCs), especially for some odor gases, the deodorization efficiency can reach more than 99%. The principle of UV photocatalytic oxidation purification method is to crack the molecular chain structure of VOCs, organic compounds such as benzene, toluene and xylene or inorganic macromolecular odor compounds under UV irradiation, decompose them into small molecular structures, atoms and intermediates, and then convert them into low molecular compounds under the action of nano catalysts, such as CO2 and H2O.

Condensation method

The methods adopted for the discharge of asphalt smoke at the asphalt tank are as follows: first, the steam recovery device is adopted, which discharges the asphalt smoke from the tank into the asphalt pipeline through condensation. Second, the condenser is used to treat the asphalt smoke in the asphalt tank. The exhaust condenser itself is composed of several circular fin tubes. The asphalt smoke is condensed and concentrated and discharged back into the tank, and the purified air is discharged into the atmosphere through the vent.

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