AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
Opto-Dielectrometric Sensors for Automated Control of Total Incombustible Content in Underground Coal Mines
OMID MAHDAVIPOUR, John Sabino, Timothy Mueller-Sim, Michael R. Shahan, Clara E. Seaman, Paul A. Solomon, Paul Wright, Richard White, Lara Gundel, Larry D. Patts, Igor Paprotny, University of Illinois at Chicago
Abstract Number: 375 Working Group: Instrumentation and Methods
Abstract Finely divided coal dust produced during underground coal-mining, i.e. float dust, which deposits throughout the coal mine can be a feedstock for coal dust explosions. To prevent such explosions, inert rock dust (limestone powder) is applied in underground areas of a coal mine. The ratio of total incombustible mass (rock dust + incombustible content of coal dust) to the total mass of the deposited dust is called total incombustible content (TIC) of the dust deposited within the mine. Regulations require that a certain minimum TIC ratio to be maintained for safe working conditions within active coal mines.
This paper presents a low-cost/low-power distributed sensing module that can continuously measure the TIC of the deposited dust. The sensing module uses continuous optical and dielectrometric methods to measure the TIC of the deposited float dust and rock dust. The main sensing components of this system are an optical reflective sensor and an interdigitated dielectrometric dust thickness/moisture monitor. The optical reflective sensor determines the TIC of the deposited dust based on optical reflection/transmission through the deposited dust stack. We present an extension of the Bouguer-Beer-Lambert Law to find the relation between the reflectivity from a layer of known thickness of a dust the mixture to the ratio of each constituent. We also present the experimental results from testing the sensor prototypes in a realistic test bed where the sensors were exposed to a realistic coal/rock dust mixture. The sensor performance and stability at different humidity levels is evaluated and the accuracy of the results are compared to the currently established best practices for measuring TIC in underground coal mines.