Design And Optimization Of Cold Material Dedusting System For Asphalt Mixing Equipment

At present,the dust generated by the cold material supply system of the asphalt mixing equipment in China is higher than the emission limit specified by the national standards.According to statistics,the annual emissions of PM and PM₁₀ of the asphalt mixing equipment with an annual output of 200,000 tons are 4320kg and 1790kg respectively.Therefore,the study of dust control technology in the cold material supply system of asphalt mixing equipment is of great significance to improve the dust collection efficiency and reduce dust pollution.The thesis first analyzes the causes of the dust generation in the cold material conveying system,and finds that dust is caused by a variety of airflows such as induced airflow,shear airflow and impact airflow.By simulating the falling process of the cold material,it is found that the distribution of the dust air flow is not uniform,the airflow velocity near the cold material is larger,and the airflow velocity in the upper part of the silo is smaller.Secondly,the structure type of vacuum hood of a 4000-type asphalt mixing equipment is compared and analyzed.According to the technological characteristics of the cold material supply system,the cold material bin chooses the oblique type dust suction hood,the batching belt machine and the aggregate belt machine choose the local sealing hood.And the air volume of the dust removal system and the resistance of the pipe network are calculated.The results show that the required air volume is 23529.25 m³/h,the wind pressure is 1300 Pa.Then,the method of computational fluid dynamics was used to conduct a numerical simulation analysis of the gas flow field and air flow distribution law in the dust hood.The results showed that the dust collection efficiency of the dust collection hood in the silo was about 41.8%,and the dust collection efficiency of the closed hood at the confidential closure of the batching belt and the connection of the aggregate belt conveyor were 69.9%and 75.9%respectively.Finally,in order to solve the problem of cyclonic vortex flow in the hood,the hood structure of the dust hood of the silo,the confidential closed cover of the distribution belt and the closed cover of the adapter of the aggregate belt conveyor were optimized and designed,and the gas flow field simulation is carried out for the improved scheme.The simulation results show that there is no cyclonic vortex flow in the optimized dust hood,and the dust removal efficiency of the silo dust hood,ingredient belt confidential closed hood and aggregate belt conveyor adapter closed hood has increased by 16%,7.48%and 2.06% respectively...