Mass concentration coupled with mass loading rate for evaluating PM2.5 pollution status in the atmosphere: A case study based on dairy barns

The satellite-based estimation of the dust mass concentration (DMC) is essential for accurately evaluating the global biogeochemical cycle of the dust aerosols. As for the uncertainties in estimating DMC caused by mixing dust and pollutants and assuming a fixed value for the mass extinction efficiency (MEE), a classic lidar-photometer method is employed to identify and separate the dust from pollutants, obtain the dust MEE, and evaluate the effect of the above uncertainties, during five dust field experiments in Northwest China. Our results show that this method is effective for continental aerosol mixtures consisting of dust and pollutants. It is also seen that the dust loading mainly occurred in the free troposphere (< 6 km), with the average mass loading of 905 ± 635 µg m−2 trapped in the planetary boundary layer. The dust MEE ranges from 0.30 to 0.60 m2 g−1 and has a significantly negative relationship with the size of dust particles. With the assumption of the dust MEE of 0.37 (0.60) m2 g−1, the DMC is shown to be overestimated (underestimated) by 20–40% (15–30%). In other words, our results suggest that the change of MEE with the size of dust particles should be considered in the estimation of DMC.

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Numerical Study on the Erosion Characteristics of U-Type Bend for Gas Solid Flow

Volume 2: I&C, Digital Controls, and Influence of Human Factors; Plant Construction Issues and Supply Chain Management; Plant Operations, Maintenance, Aging Management, Reliability and Performance; Renewable Energy Systems: Solar, Wind, Hydro and Geothermal; Risk Management, Safety and Cyber Security; Steam Turbine-Generators, Electric Generators, Transformers, Switchgear, and Electric BOP and Auxiliaries; Student Competition; Thermal Hydraulics and Computational Fluid Dynamics ◽

10.1115/power-icope2017-3412 ◽

2017 ◽

Cited By ~ 1

Author(s):

Yu Wang ◽

Qi He ◽

Ming Liu ◽

Weixiong Chen ◽

Junjie Yan

Keyword(s):

Particle Size ◽

Erosion Rate ◽

Loading Rate ◽

Pipe Wall ◽

Numerical Study ◽

Pulverized Coal ◽

Mass Loading ◽

Two Phase ◽

Inlet Velocity ◽

Pipe System

In pulverized coal-fired plant, the U-type bend is commonly used in flue gas and pulverized coal pipe system to due to the constraints of outer space. And gas-solid two-phase flow exists in these pipelines. The erosion of the pipe has significant effect on the safety and reliability of pipelines. In present paper, the erosion characteristics of U-type bend were investigated through CFD (Computational Fluid Dynamics) method. The wear distribution on the pipe wall was obtained. And the particle flow characteristics in U-type bend were analyzed. The influence of inlet velocity, mass loading rate and particle size on the erosion rate was studied as well. Result suggested that the maximum erosion rate increases exponentially with the increase of inlet velocity. And maximum erosion rate increases linearly with the increasing mass loading rate. Increasing particle size can aggravate the wear on the pipe wall.

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Investigation of the Sedimentation Property of Backfill Material on the Basis of Rheological Test: A Case Study of Iron Tailings

Journal of Chemistry ◽

10.1155/2018/9530767 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Yong Wang ◽

Aixiang Wu ◽

Lianfu Zhang ◽

Hongjiang Wang ◽

Fei Jin

Keyword(s):

Shear Stress ◽

Shear Rate ◽

Mass Concentration ◽

Filling Material ◽

Quantitative Characterization ◽

Filling Materials ◽

Characterization Studies ◽

Rheological Test ◽

Sedimentation Property

Sedimentation of filling materials could cause pipe blocking accident in mines. However, few quantitative characterization studies have investigated the sedimentation characteristics of filling materials. In this study, the sedimentation property of iron tailings with a cement-sand ratio of 1 : 4 and mass concentration of 73%∼82% was investigated based on rheology measurements. Results showed that shear stress increased as shear rate rose from 0 s−1to 120 s−1. The shear stress increased as the filling material concentration increased as well. However, when the shear rate was reversed from 120 s−1to 0 s−1, the shear stress presented an increase-constant-decrease change pattern as the mass concentration increases in the rheological curve. Accordingly, the sedimentation performance of iron tailings filling material was divided into three types: intense sedimentation (the ascending rheological curve) in the mass concentration range of 73%∼76%, slight sedimentation (the constant rheological curve) in the mass concentration range of 77%∼79%, and almost no sedimentation (the descending rheological curve) in the mass concentration range of 80%∼82%. The associated mechanism involving slurry mass concentration-rheological curves-sedimentation performance was illustrated. A correlation between the pipeline rheology and filling material sedimentation performance was established, which provides a practical guide to avoid pipeline blocking while transporting the filling material.

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Formation and evolution mechanism of regional haze: a case study in the megacity Beijing, China

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-16259-2012 ◽

2012 ◽

Vol 12 (7) ◽

pp. 16259-16292 ◽

Cited By ~ 5

Author(s):

X. Liu ◽

J. Li ◽

Y. Qu ◽

T. Han ◽

L. Hou ◽

...

Keyword(s):

Wind Speed ◽

Mass Concentration ◽

Empirical Relationship ◽

Surface Wind ◽

Atmospheric Environment ◽

Evolution Mechanism ◽

Regional Haze ◽

Formation And Evolution ◽

The Government

Abstract. The main objective of this study is to investigate the formation and evolution mechanism of the regional haze in megacity Beijing by analyzing the process of a severe haze that occurred 20–27 September 2011. Mass concentration and size distribution of aerosol particles as well as aerosol optical properties were concurrently measured at the Beijing urban atmospheric environment monitoring station. Gaseous pollutants (SO2, NO-NO2-NOx, O3, CO) and meteorological parameters (wind speed, wind direction, and relative humidity (RH)) were simultaneously monitored. Meanwhile, aerosol spatial distribution and the height of planetary boundary layer (PBL) were retrieved from the signal of satellite and LIDAR (light detection and ranging). Results showed that high intensity of local pollutants from Beijing urban source is the fundamental cause that led to the regional haze. Meteorological factors such as higher RH, weak surface wind speed, and decreasing height of PBL played an important role on the deterioration of air quality. New particle formation was considered to be the most important factor contributing the formation of haze. In order to improve the atmospheric visibility and reduce the occurrence of the haze, the mass concentration of PM2.5 at dry condition should be less than 60 µg m−3 in Beijing according to the empirical relationship of visibility, PM2.5 mass concentration and RH. This case study may provide valuable information for the public to recognize the formation mechanism of the regional haze event over the megacity, which is also useful for the government to adopt scientific approach to forecast and eliminate the occurrence of regional haze in China.

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