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Prevention and control measures for pollutants in asphalt mixing equipment - asphalt smoke

Aug 22, 2019

Is there any pungent smell on the production site of your asphalt mixing plant? In natural gas-fueled mixing plants, bitumen smoke is the most important air pollution discharge, which is closely related to the prevention and control measures taken by production equipment. How to prevent and treat asphalt fume generated by asphalt mixing plant during production? There are several ways to solve this.

Incineration treatment

The asphalt smoke is led to the burner by the finished product warehouse, and the air introduction system sucks the asphalt smoke into the flame of the burner, and the collected flue gas is ejected from the annular air duct of the burner, and uniformly enters the air duct at the flame in the drying cylinder.

The most efficient method of collection at the discharge opening is to provide a passage for the rolling door at the discharge opening. Asphalt flue gas is collected through the adjustment control of the windshield by installing a control unit at the discharge port.

Adsorption collection

1 static

The asphalt flue gas passes through the primary passage, and the asphalt smoke particles are ionized by the high-voltage direct current electrode to carry a negative charge. After entering the secondary passage, the hydrocarbon particles are separated from the gas flow by the positive electrode adsorption, and the treated gas flow is directly discharged into the atmosphere. Electrostatic precipitator electrodes should be cleaned regularly to eliminate particle buildup.

2 media filtration

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

3 powder wrapped in smoke

Similar to the bag filter, the powder-wrap filter unit incorporates a fiber material into the asphalt fume pipe to thoroughly mix it with the bitumen smoke and then remove it by a bag filter. The powder-wrap filter uses three filtration methods: impact, interception, and Brownian diffusion. Impact refers to the collision of asphalt fume particles with the filter. This method is effective for particles larger than 3 μm; interception is used to collect small particles in the range of 1 to 3 μm; Brown diffusion is used to collect submicron particles. The principle is that the submicron particles generate Brownian motion such as convolution and translation along the curved path under the action of the airflow, and are collided with the filter fiber to be collected, thereby being removed from the airflow. The powder wrap method requires regular replacement of the filter to meet the pressure difference requirements of the precipitator.

Low temperature plasma flue gas purification

In the low-temperature plasma asphalt flue gas purification technology, there are three main principles and functions of high-voltage pulse high-energy electron radiation, ultraviolet light decomposition and ozone oxidation. This technology can well destroy the macromolecular structure in asphalt smoke 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 state, forming an excited state molecule, and the chemical bond of the internal structure of the hydrocarbon substance is broken to form an active substance, and the final product It is CO2 and H2O.

UV photocatalytic oxidation purification method

UV photocatalytic oxidation purification method has strong ability to decompose asphalt smoke molecules, and can effectively remove volatile organic compounds (VOCs), especially for some malodorous gases, the deodorization efficiency is up to 99%. The principle of UV photocatalytic oxidation purification method is to cleave the molecular chain structure of VOCs, benzene, toluene, xylene and other organic substances or inorganic high molecular malodor compounds under UV irradiation, and decompose into small molecular structures, atoms and intermediates. And then converted into low molecular compounds such as CO2 and H2O under the action of nanocatalysts.

Condensation method

The methods for the asphalt soot discharge at the asphalt tank are as follows: First, a steam recovery device is used, which discharges the asphalt smoke from the tank into the asphalt pipe through condensation. The second is to treat the asphalt smoke in the asphalt tank by a condenser. The exhaust condenser itself is composed of a plurality of circular fin tubes. The asphalt smoke is condensed and concentrated and discharged into the tank, and the purified air is discharged into the atmosphere by the vent.