Effects of throughput and operating parameters on cleaning performance in air-and-screen cleaning unit: A computational and experimental study

The influences of throughput and operating parameters on internal airflow and cleaning performance for the air-and-screen cleaning unit were investigated. The throughput experiment showed that, the airflow velocities above the vibrating screen decreased by 1.3-15.5% for every 1.0 kg s(-1) increase of throughput and which below the vibrating screen decreased by 2.7-8.1%. As a result, the cleaning performance has declined. Then, the airflow velocity measurement and cleaning performance tests were taken under 4.0 kg s(-1) throughput with single factor experiment in which fan speed, airflow deflector angle and sieve opening were as factors. And, the Computed Fluid Dynamic (CFD) numerical simulations were carried out to analyze the movement trend of internal airflow as an auxiliary analysis method. The following viewpoints were obtained, the fan speed has a large effect on cleaning performance by affecting the overall airflow velocities in the cleaning unit. And, the airflow velocities above the vibrating screen increased from 0.2 m s(-1) to 0.4 m s(-1) for every 150 r min(-1) increase of fan speed, which below the vibrating screen increased from 0.4 m s(-1) to 1.1 m s(-1); The highest airflow velocities area above the vibrating screen moved forward to the central position in the longitudinal direction as the airflow deflector angle increased; With the reduction for each 4 mm of chaffer opening, the airflow velocities above the vibrating screen increased by 0.2-0.4 m s(-1). At last, making mathematical relations between each operating parameter and the cleaning performance, and proposing the method of adjusting the single operating parameter under rated condition according to the throughput. They provide a basis for real-time automatic adjustment of the operating parameters in the air-and-screen cleaning unit.