Electrostatic removal of ultrafine carbon black with square-grooved collecting plates: Insights for capturing black carbon emitted from ships

Abstract

Ships and other mobile pollution sources emitted massive ultrafine and low-resistivity particles containing black carbon (BC), which were harmful to human health and were difficult to capture by conventional electrostatic precipitators (ESPs). In this study, nanoscale carbon black was adopted as simulated particles (SP) with similar physicochemical properties for black carbon emitted from ships (SP-BC) to investigate the feasibility of using an ESP with square-grooved collecting plates for the removal of SP-BC at low backpressures. The increased applied voltage significantly improved the total collection of SP-BC whereas may also promote the conversion of relatively larger particle size SP-BC into nano-size below 20 nm. The outlet number concentration of SP-BC under 27 kV at 130°C was three times that of the inlet. While the reduction of the flow rate could strengthen the capture of SP-BC below 20 nm, and under the combined action of low flow rate and maximum applied voltage, the collection efficiency of 20-100 nm SP-BC could exceed 90%. In addition, the escape and capture characteristics of SP-BC under long-term rapping were revealed. The square-grooved collecting plate could effectively restrain the re-entrainment of collected SP-BC generated by rapping, and the nanoscale SP-BC was trapped in the grooves after rapping. The results could provide insights into the profound removal of massive nanoscale black carbon emissions from mobile sources.