Yubin Wei

Application of Distributed Optical Fiber Temperature Sensing System Based on Raman Scattering in Coal Mine Safety Monitoring

The principle and design of the distributed optical fiber temperature sensing system based on Raman scattering is presented in this paper. The spatial resolution is enhanced by reducing the pulse width of the light source and high speed progressive average etc. The distributed optical fiber sensor not only has the characteristics of resistance to electromagnetic interfere, against fire and so on, but also it can sense the change of temperature along the optical fiber by the form of continuous distance. Because of its ascendency and the augmented performance, This paper also introduces the example used in coal mine goaf temperature monitoring and data analysis.The principle and design of the distributed optical fiber temperature sensing system based on Raman scattering is presented in this paper. The spatial resolution is enhanced by reducing the pulse width of the light source and high speed progressive average etc. The distributed optical fiber sensor not only has the characteristics of resistance to electromagnetic interfere, against fire and so on, but also it can sense the change of temperature along the optical fiber by the form of continuous distance. Because of its ascendency and the augmented performance, This paper also introduces the example used in coal mine goaf temperature monitoring and data analysis.

High-resolution fiber carbon monoxide sensing system and its data processing

Carbon monoxide is one of the important gases need to be detected in coal mine safety. Detection technology based on signature gas is the primary means of spontaneous combustion forecasting of coal goaf area. Because of the high accuracy requirement of CO concentration in the coal mining applications, we had to introduce more data processig methods to improve the signal-to-noise ratio (SNR), finally to achieve the requirements of coal mining. Therefore, we used three data processing methods to eliminate noises of the CO sensing system which based on the tunable diode laser absorption spectroscopy (TDLAS): Fourier transform, least-squares fitting and Kalman filter. The results show that the combination of three data processing methods had a good inhibitory effect of random noise and interference fringes, etc. and significantly improved the system detection accuracy, the minimum detectable spectral absorption rate could be increased by an order of magnitude. So this high-resolution fiber CO sensing system can better meet the needs of coal mine safety.

All-Optical Remote Sensing Monitoring Technique of Methane Concentration Based on Tunable Diode Laser Absorption Spectroscopy

A novel all fiber optic sensing monitoring technique is researched for remotely detecting the concentration of methane gas. The triangular signal is used to modulate the light wavelength of the DFB laser. The narrow absorption line of the laser eliminates the cross sensitivity to moisture, ethane or other gases. With the use of the optical fiber links between monitor and sensor header, the system can provide remote and online monitor information. Since the sensor head is made without any active electrical components, it is intrinsically safe when used in the hazard environment such as coal mines. The results show that the monitoring technique has a great application in the methane extraction pipe-line, coal mines and the environment detection.

High-resolution fiber methane sensor based on diode laser and its data processing

Tunable diode laser absorption spectroscopy (TDLAS) based optical fiber methane sensing technology has a number of advantages compared with conventional electronic methane sensor device, such as high Precision, passive and intrinsically safe in explosive and hazardous environment as well as immune to electro-magnetic interference. In order to accurately measure the oxidation rate of coal mine ventilation air methane oxidizer system, and Meet requirements for accurate measurements to the oxidizer exhaust emissions, A Fiber optic methane monitor based on Distributed feedback tunable diode (DFB) laser of 1.65um central wavelength is demonstrated. We use a reflective chamber of only a 10cm effective optical path as sensing gas cell. By the data processing of fitting baseline method, we remove the effect of the baseline tilt of background Spectral. The system achieves 0 to 0.1% measure range and 5.8*10E-6 minimum detection sensitivity, and meets the requirements of high accuracy, real-time measure to the oxidizer exhaust emissions.

Research of optic fiber CO concentration monitoring virtual system based on TDLAS

The online monitoring of the Coal Mine inflammable and explosive gases based on optic fiber sensing technologies, is the main research of spontaneous combustion forecasting system of coal goaf area. In use of the LabViews virtual instrument development capability, CO concentration monitoring virtual system has been established based on the tunable diode laser absorption spectroscopy(TDLAS) technology. According to comparison of the results of the virtual simulation system and the actual monitoring system, indicate that the virtual system can reflect the impact of second harmonic by dynamic parameters such as concentration, temperature and pressure truly and accurately, provide theoretical guidance and reference for the overall design of the gas monitoring system.

Optical fiber oxygen sensor based on DFB laser absorption spectroscopy

This paper describes an optical fiber oxygen sensor based on wavelength scanning and spectrum absorption technique. An open path optical gas chamber is employed to analyze the absorption lines of oxygen in visible region. The oxygen sensor works in the concentration range 0-100% oxygen with good performance in stability and sensitivity. The precious is less 0.5% over 30 hours in atmosphere. The results show that it will have a great potential application in the harsh environments.

Research progress of photonic crystal fibers for gas sensing

Because of its special structure, photonic crystal fiber(PCF) has shown great potential in gas sensing. Probe beam with the test gas can directly interact within a PCF. PCF gas sensor with a very small amount of gas can be interact with light in optical fiber in a long distance. And you can change the parameters of the fibers can be improved sensor sensitivity, etc. The status of solid core PCF and hollow-core PCF as a gas sensor is introduced respectively in this paper.

The monitoring system of the pipeline safety of the coal mine gas drainage based on the optic fiber sensing technology

Based on the technology of the spectrum absorption and the FBG, the monitoring system realize on line detection of the concentration of methane and oxygen, the temperature and the pressure of the gas in pipeline, and in order to improve the accuracy of the gas detection, we induce the compensation to the gas concentration using the data of the temperature and the pressure. In order to have a effective utilization of the methane in the coal mine gas drainage system, we have to have a accurate measurements of the concentration, the temperature and the pressure of the gas in pipeline. At the same time the dynamic monitoring of the concentration of Oxygen is a sign of the leakage of the pump. This paper gave some data detected in the field of the coal mine gas drainage system.

Laser Methane Sensor with the Function of Self-Diagnose

Using the technology of tunable diode laser absorption spectroscopy and the technology of micro-electronics, a fiber laser methane sensor based on the microprocessor C8051F410 is given. In this paper, we use the DFB Laser as the light source of the sensor. By tuning temperature and driver current of the DFB laser, we can scan the laser over the methane absorption line, Based on the Beer-Lambert law, through detect the variation of the light power before and after the absorption we realize the methane detection. It makes the real-time and online detection of methane concentration to be true, and it has the advantages just as high accuracy， immunity to other gases ，long calibration cycle and so on. The sensor has the function of adaptive gain and self-diagnose. By introducing digital potentiometers, the gain of the photo-electric conversion operational amplifier can be controlled by the microprocessor according to the light power. When the gain and the conversion voltage achieve the set value, then we can consider the sensor in a fault status, and then the software will alarm us to check the status of the probe. In addition, we introduce the feedback of the temperature to compensate the environment effects, So we improved the dependence and the stability of the measured results. At last we give some analysis on the sensor according the field application and according the present working, we have a look of our next work in the distance.

Multi-Channel Optical Fiber Methane Monitoring System Based on Laser Absorption Spectroscopy

A multi-channel optical fiber methane monitoring system is researched for detecting the concentration of methane gas. In this system, distributed feedback laser is employed as light source. The narrow absorption line of the laser could effectively eliminates the cross sensitivity to moisture, ethane or other gases. Since the sensor head is made without any active electrical components, it is intrinsically safe when used in the hazard environment such as coal mines. The results show that the monitoring system has a great application in the comprehensive utilization of coalmine methane and ventilation air methane.