Improved Spray Scavenging of Particulates via Acoustical Excitation of Drop Oscillations

Details

• Personal Author:
  Saylor JR
• Description:
  In spite of significant efforts that have been made to protect the respiratory health of mine workers, exposure to coal dust, silica dust, diesel particulate matter and other suspended particles continues to threaten the pulmonary health of the mining work force. This is true in both surface mining and underground mines. Within the mining work force illnesses that continue to be common are silicosis and coal workers' pneumoconiosis (CWP or black lung disease). Of greatest threat to respiratory health are particles that are approximately one micron in diameter. Particles which are much larger than this size range tend to be captured in the oropharyngeal area of the human respiratory system. However, significant alveolar deposition occurs for particles ranging in diameter from O.Olum to 10um (EPA, 1999). Water sprays are used in many aspects of mining in an attempt to reduce the level of particulate matter in the air that is breathed by the mining work force. Sprays are used to wet the gallery walls where cutting occurs, as well as to wet recently cut rock and coal. Additionally, sprays are employed in wet scrubbers that are used in the cabs of mining vehicles. Wet scrubbers are also used on the sides of continuous mining machines where air is pulled from the cutting region, directed through the scrubbers and then returned at the rear of the continuous mining machine in the vicinity of the operator. Unfortunately, while water sprays can be very effective at removing relatively large and very small particles from air, for particles precisely in the 0.01 to 10 um range that are most dangerous to respiratory health, water sprays are relatively ineffective. Because a large installed base of water spraying nozzles and affiliated equipment already exists, the focus of the proposed work was to improve the efficacy of such sprays, rather than to develop a completely different method for lowering dust levels in mines. Specifically, the use of ultrasonic excitation of the spray was proposed as a means for improving the ability of sprays to scavenge particulate matter from the air. In this work, an ultrasonic standing wave was generated between an ultrasonic transducer and a reflector. This standing wave field forms 'accretion disks' in the air. These are regions where the air flow collects and anything that is suspended in the air is concentrated. A spray was directed through this standing wave field, along one axis, and a particle-laden air stream was directed through the standing wave field along a perpendicular axis. In the accretion disks, the particles and the spray drops were concentrated and brought into close proximity with each other. The spray drops grew and fell to the floor, removing particles with them. In short, a small scrubber was developed, where ultrasonics were used to increase the ability of the spray to remove particles. Improvements of nearly 150% were attained. [Description provided by NIOSH]
• Subjects:
  Air Pollutants, Occupational Air Pollution, Indoor Coal Dust Irritants Lung Lung Diseases Men Mining Occupational Health Particulate Matter Respiratory System Respiratory Tract Diseases Safety Silicon Dioxide Vehicle Emissions

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• Keywords:
  Air-contamination Airborne-dusts Airborne-particles Black-lung Coal-dust Diesel-emissions Diesel-exhausts Dust-exposure Dust-particles Dusts Exposure-levels Humans Mineral-dusts Miners Mining-industry Particulate-dust Particulates Pneumoconiosis Pulmonary-disorders Pulmonary-function Pulmonary-system Pulmonary-system-disorders Respirable-dust Respiration Respiratory-irritants Respiratory-system-disorders Silica-dusts Silicosis Sprays Underground-miners Underground-mining Wet-scrubbers

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• Series:
  Grant Final Reports
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  OSHA Region 4 ; South Carolina
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-28
• NIOSHTIC Number:
  nn:20042334
• NTIS Accession Number:
  PB2013-105835
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R01-OH-009546, 2012 Oct; :1-28
• Contact Point Address:
  Prof. John R. Saylor, Department of Mechanical Engineering, 229 Fluor Daniel EIB, Clemson University, Clemson, SC 29634-0921
• Email:
  jsaylor@clemson.edu
• Federal Fiscal Year:
  2013
• Performing Organization:
  Clemson University
• Peer Reviewed:
  False
• Start Date:
  20080801
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20120731
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:5da80f743e5e086b6238fb4aa97a7913dac06b45f40352b6bc49fe9fc3151505a6e3180b8b08efc55be19e0d26ee069f062e0f2f6cdeb0791417bbf5a3065ac2
• Download URL:
  https://stacks.cdc.gov/view/cdc/218519/cdc_218519_DS1.pdf
• File Type:
  [PDF - 10.20 MB ]