Sludge low-temperature drying with mainly non-phase change in mere seconds based on particle high-speed self-rotation in cyclone

Improper sludge treatment will cause serious environmental problems, and sludge drying is the key to effective treatment. Almost all the existing sludge drying technologies use heating to overcome the great latent heat of moisture vaporization, which leads to high drying energy consumption. In this study, based on the particle high-speed self-rotation in the cyclone and micro-interface oscillations, the cyclone self-rotation drying (CSRD) technology was developed. It can realize drying of the dewatered landfill sludge (DLS) and the urban sewage dewatered sludge (UDSS) with mainly non-phase change. The obtained results reveal that at low carrier gas temperatures (< 100 ?) and very short residence time (< 15 s), the moisture content of the DLS decreased from 53% to 6.85%, and that of the UDSS decreased from 67% to 18.92%. Through calculation, the proportions of moisture non-phase change removal during the CSRD process touched 68.94% and 63.39%, respectively. Based on the experimental studies, we proposed an enlarged industrial application program (50 t/d) for the UDSS drying by employing the CSRD technology. The operating cost was 159.69 CNY/t H2O, showing prominent advantages. This study can provide guidelines for the practical application of CSRD technology and fill the scientific gap in the field of moisture non-phase change separation for sludge drying.

Automated summary

Improper sludge treatment can lead to serious environmental problems, and sludge drying is crucial for effective treatment. Most existing sludge drying technologies consume high energy due to the use of heating to overcome moisture vaporization. This study developed the cyclone self-rotation drying (CSRD) technology based on particle high-speed self-rotation in the cyclone and micro-interface oscillations. CSRD can achieve non-phase change drying of dewatered landfill sludge (DLS) and urban sewage dewatered sludge (UDSS) with low energy consumption and high moisture removal efficiency.