Modeling of fugitive dust emission and control measures in stone crushing industry
專題討論碩一
79842001劉昱麟
Abstract
• A cluster of 72 stone crushing units located at Trisoolam in Chennai is a source of high levels of dust generation in the vicinity of the crushers and in the communities surrounding them.
• FDM, ISCST3 and AERMOD were employed for prediction of dust emission from stone crushers on the surrounding areas.
• The control measures adopted at these stone crushing units are not sufficient enough to bring down the concentration within the stipulated limits.
Materials and methods
• Weather monitoring• Ambient air quality monitoring network design
• Air quality monitoring• Particle size analysis• Emission rate estimation• Assessment of occupational exposure level
• Modeling of fugitive dust emissions• Data requirements of the models• Model prediction
氣象監測鄰近空氣品質監測系統
空氣品質監測粒徑分析
模式模擬預測
估算排放率職業性暴露性層級評估
模式應用模式參數設定
Study areaRSPM 可吸入懸浮顆粒物
TSPM 總懸浮顆粒物
• Weather monitoring Wind speed
Wind direction
Temperature
Pressure
Rainfall
Humidity
• Ambient air quality monitoring network design 17 sites across the area
10 location at stone crushing units
7 in ambient air
風速
氣溫風向
氣壓
濕度降雨
Modeling of fugitive dust emissions(1/3)
• FDM(揚塵擴散模式 ) 1. Computerized Gaussian plume air quality dispersion model
2. Three basic types of sources: point, line, and area
3. Designed for estimation of concentrations and deposition impacts from fugitive dust sources.
4. Gravitational settling velocity and deposition velocity are calculated.
• ISCST3(工業污染短期模式 )
1. Based on the straight line, steady state Gaussian plume equation.
2. Three basic types of sources: point, volume, and area.
3. Estimates the concentration or deposition value for each source and receptor combination for each hour of input meteorology, and calculates user selected short term averages.
4. Includes a new wet deposition algorithm and also incorporates the COMPLEX1 screening model algorithms.
Modeling of fugitive dust emissions(2/3)
• AERMOD(美國環境保護逸散模式 )
1. It serves as a complete replacement for ISCST3.
2. It assumes the concentration distribution to be Gaussian in both the vertical and horizontal in the stable boundary layer (SBL), but the vertical distribution is described to bi- Gaussian probability density function in the convective boundary layer.
3. The major improvements that AERMOD brings to applied dispersion modeling is its ability to characterize the Planetary Boundary Layer (PBL) through both surface and mixed layer scaling.
Modeling of fugitive dust emissions(3/3)
Model prediction
1. Emission rate
2. Particle size distribution of dust
3. Meteorology
4. Source-receptor geometry
5. Treatment for deposition
6. Scavenging effect
Result and discussion
• Weather monitoring• Air quality monitoring• Particle size analysis• Emission rate estimation• Assessment of occupational exposure level• Model prediction• Control measures• Impact zone
Dust concentration at sourceDust concentration around stone crushing units
• Weather monitoring direction in southwest 19%
direction in west 18.5%
direction in west of southwest 14%
wind speed in 5~10kmph 25%
wind speed in 10~15kmph 15%
ave. wind speed is 9.65kmph
Air quality monitoring (Dust concentration at
source)
Air quality monitoring (Dust concentration around stone crushing units)
Particle size analysis
PM30
PM15
PM2.5
73.5 %
14.3 %
45 %
• Emission rate estimation micro-meteorological condition
location of source and receptor
upwind and downwind direction
3.89g/s 2.778g/s(USEPA)
>>
• Assessment of occupational exposure level
Occupational Safety and Health Administration
National Institute of Occupational Safety and Health
American Conference of Governmental Industrial Hygienists
Indian Factory Act.
職業安全與健康機構 (15mg/m3 for total)
印度工業法規
國家安全與健康協會 (10mg/m3 for TSPM)美國政府工業衛生聯盟 (10mg/m3 for TSPM & RSPM)
EXCESSEXCESS
Model prediction
Model prediction
Control measures
Control measures
1. Dust containment cum suppression system for the equipment2. Construction of wind breaking walls3. Construction of metalled roads within the premises4. Regular cleaning and wetting of the ground within the premises
1. Reducing drop heights2. Spray nozzle for periodical wetting of dust3. Collection of fine powder below ground level and completem cover
ing4. Covering of loaded trucks using tarpaulins while transportation5. Arresting re-entrainment of settled dust from surfaces
Implementation of following pollution control measures at source
Growing of a green belt along the periphery
In addition the following good house keeping were also implemented to further reduce the dust emissions
Impact zone
N
W E
S
風向N
W E
S
風向
Conclusion
• The adequacies of the control measures is not sufficient enough to bring down the concentration within stipulated limits in residential areas located less than 300 m from stone crushing activity in the eastern direction.
• There is a scope for further improvement of control measures at these stone crushing units in Trisoolam area.