Field measurements on particle size distributions and emission characteristics of PM10 in a cement plant of China

Abstract

The particle size distributions (PSDs) and the characteristics of the particulate matter (PM) from cement plants are of importance for the air pollution control strategies. The study focuses on the PSDs and emission characteristics of PM10 in the flue gas from the preheater and in the hot air out from the clinker cooler in a cement plant equipped with a conditioning tower, two raw mills, a gravity settler and two fabric filters. A Dekati low pressure impactor (DLPI) with a cyclone was performed to sample the PM10 at the inlet/outlet of the above devices. The PM10 at the outlet of SP boiler and at the inlet of the gravity settler both present a bi-modal distribution, with a fine mode at 0.1–0.4 μm and a coarse mode at 1.0–5.0 μm. The PM10 emitted from the flue gas and the hot air into the atmosphere both present a tri-modal distribution, with a fine mode at 0.2–0.5/0.06–0.2 μm, a middle mode at 0.5–2.5/0.2–0.6 μm and a coarse mode at 5.0–10.0/3.0–6.0 μm. The mass concentration of PM2.5 increases by 17.74% at the outlet of the raw mill due to the mechanical fragmentation and flow transport. The spraying and cooling of the conditioning tower promote the agglomeration and growth of fine particulates, and reduce the concentration proportion of PM2.5 to PM10 from 89.40 to 70.93%. The emission factors of PM10, PM2.5 and PM1 in the flue gas are 0.017–0.031, 0.005–0.015 and 0.002–0.007 kg/t, respectively; while they are 0.005, 0.003 and 0.001 in the hot air, respectively.