A New Angular Light Scattering Measurement of Particulate Matter Mass Concentration for Homogeneous Spherical Particles.

Under the condition of ultra-low emission for power plants, the particulate matter concentration is significantly lower than that of typical power plants a decade ago, which posed new challenges for the particulate matter monitoring of stationary emission. The monitoring of particulate matter mass concentration based on ensemble light scattering has been found affected by particle size. Thus, this study develops a method of using the scattering angular distribution to obtain the real-time particle size, and then correct the particulate matter concentration with the real-time measured particle size. In this study, a real-time aerosol concentration and particle size measurement setup is constructed with a fixed detector at the forward direction and a rotating detector. The mass concentration is measured by the fixed detector, and the particle size is measured from the intensity ratio of the two detectors. The simulations show that the particle size has power law functionality with the angular spacing of the ripple structure according to Mie theory. Four quartz aerosols with different particle size are tested during the experiment, and the particle size measured from the ripple width is compared with the mass median size measured by an electrical low pressure impactor (ELPI). Both techniques have the same measurement tendency, and the measurement deviation by the ripple width method compared with ELPI is less than 15%. Finally, the measurement error of the real-time mass concentration is reduced from 38% to 18% with correction of the simultaneously measured particle size when particle size has changed.

Effects of kaolin-limestone blended additive on the formation and emission of particulate matter: Field study on a 1000 MW coal-firing power station.

Effects of a blended additive made of kaolin and limestone on the formation and emission characteristics of particulate matter (PM) was discussed for the first time. Systemic characterizations on the concentration, size distribution, elemental composition, micromorphology, specific resistivity of the PM were performed. Results revealed that the blended additive diminished the mass concentrations of the ultrafine PM and PM2.5 out of the furnace by 29.77 % and 40.91 % respectively. Interestingly, the additive also significantly reduced coarse PM, with the reduction efficiency for PM in 0.3-1 µm of ∼43 %. The additive captured the mineral vapors and thereby suppressed their migration into the ultrafine PM. Well, interactions among additive and ash promoted melting of the additive/ash particles. This improved the scavenging of both ultrafine and coarse PM via the liquidus capture mechanism. After the electrostatic precipitators (ESPs), emission of the ultrafine PM slightly increased after adding the additive because of the increasing of the specific resistivity of the ash particles and the reduction of electronegative gas (e.g., SO2) in the ESPs. The emission of total PM2.5 decreased by 32.31 % as less fly ash entering ESPs. Additionally, the leaching behaviours of heavy metals Cr, Mn, As and Pb in the fly ash were investigated.