The belt conveyor serves as the main coal transport equipment in a coal mine and its safe operation is the lifeline of safety in coal mine production. However, traditionally, monitoring for ignition and for roller faults along the belt conveyor is problematic and so this paper puts forward an approach using radial grating vibration sensing technology for both belt conveyor roller vibration monitoring. This can then be used to predict the fault state in the roller and its position, using distributed optical fiber temperature measurement technology which can be used for ‘hot spot monitoring’. This enables better fire prevention along the belt conveyor, which plays a positive and effective role in better mine safety.
Built on a design developed from an advanced mathematical model, a practical fiber optic sensor, which is an analog of the familiar ‘hot-wire’ wind velocity monitor is developed, as an intrinsically-safe sensor device for coal mining monitoring applications. The underpinning optical fiber-based principle used is the shift in the center wavelength of a Fiber Bragg Grating which is cooled by the gas flowing over it and the device sensitivity found was determined to be ~1370pm per unit m/s wind velocity (in the range of 0-0.57 m/s), ~109pm per unit m/s in the range 0.57-2.26 m/s and ~33pm per unit m/s in the range of 2.26-5.66 m/s. In this paper, the factors that influence the device response time, such as the sensor probe surface heat transfer coefficient, wind (gas) velocity and pump power have been investigated in the laboratory. It was found that the greater the surface dissipation factor of the sensor, the shorter the response time, furthermore, the response time was observed to decrease as the wind velocity increased. A method of further shortening sensor response time using wind speed variation slope is proposed.
Surface Enhanced Raman Scattering (SERS) is typically observed with the substrate in a liquid medium and it has been proposed as a promising technique for detecting low levels of pollutants in liquids. The design and fabrication of an optical fibre SERS sensor based on Au nanoparticles (Au-NPs), which is self-assembly immobilized onto the end surface of an optical fibre is described. Two toxic materials, Rhodamine 6G (R6G) and crystal violet were analysed using this optical fibre SERS sensor combined with portable Raman spectrometer. Our proposed fabrication and analytical method offers a rapid, cheap and disposable trace detection capability for toxic materials in the field.
Optical humidity measurement is essential in current industry, especially in environment with adverse electromagnetic field and strong corrosion. This paper focus on the fabrication and test of a novel fiber bragg grating based humidity sensor. The sensor is fabricated by uniformly coating humidity sensitive material on fiber bragg grating. The sensing characteristic test of the sensor shows: the wavelength shift following humidity is linear; the minimum response time of the 2-layer coated sensor is 10 s with sensitive coefficient can be controlled by changing coating time; hygroscopic hysteresis of 3-layer coated sensor is 2.7`%RH. Therefore, the sensor is promising to be used to meet the quick response and in vivo measurement demand in industry.