Recent Advances in Automatic Control, Information and Communications
Parameters Monitoring for Hazardous Areas using HP VEE Graphical Software CAROL ZOLLER*, REMUS DOBRA* TRAIAN BURDEA* * Department of Electrical and Power Systems, University of Petrosani * Address University str., no. 20, Petrosani ROMANIA
[email protected] [email protected] Abstract: - In this work it is described a simulated monitoring system for the main parameters from hazardous areas, like coal mining exploitations. This parameter is the methane gas (CH 4 ), although the presented monitoring system can be adapted easily in order to be used for other important parameters (e.g. CO and CO 2 concentrations, tunnel wind speed, negative pressure and temperature). A synthetic flowchart of the GH 4 monitoring system is presented and based on the operating principles of some dedicated gas sensors has been developed a virtual instrument which accurately models the functionality of a mining processing plant. The virtual instrument, used for methane gas processing system development, is obtaining using adequate interfaces, a data acquisition board and by the means of HP VEE visual programming language.
Key-Words: - Methane gas, hazardous area, graphical software, computer modeling, virtual instrumentation. The degasification system works together with the ventilation system and the mining operations and because of that it is important to provide a propitious monitoring system, regarding all the parameters from mining exploitation, (by means of measuring instruments, monitoring and controls techniques, and good communications systems) in order to optimize each of the three functions.
1 Introduction The coal mine exploitation need to be monitored in terms of methane gas (but also environmental parameters, such as: CO and CO 2 concentrations, tunnel air flow, pressure, temperature, etc.) using latest technologies which provides information about the methane concentrations in different parts of mining exploitation. The methane gas is stored in pockets within a coal until it is released during coal mining operations and these methane concentrations are monitored using special transducers dedicated to potentially explosive atmospheres. If the methane gas concentration increase, the mining safety system will give a signal in order for the mining area to be ventilated. The ventilation air systems are used in underground mines to maintain low concentration levels of CH 4 during mining operations. Ventilation systems maintain a CH 4 concentration below 1%, in the preparation and gallery areas and below 1,8% in the stope working area, by using large fans to inject fresh air from the surface into the mine, thereby lowering the in-mine CH 4 concentration. This ventilation air is extracted from the mine and vented to the atmosphere through ventilation shafts or bleeder shafts [3].
2.1 Analysis method of the methane monitoring system In figure 1 is presented the analysis of methane gas concentration using some dedicates CH 4 transducers, which achieves a voltage frequency conversion in order to measure the methane concentration from the mining working area, heaving three alarm thresholds programmed.
2 Analysis method and flowchart of the GH 4 monitoring system Good monitoring systems ensure that the concentration of the methane gas is above the limiting value imposed by the coal mine standards.
ISBN: 978-960-474-316-2
Figure 1. Analysis of the methane gas concentration
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concentration is verified; in case when the methane concentration is higher than the methane allowable limit the switching-on command is locked and the energetical operator is warned. The next sequence is for checking if the electrical parameters (i.e. voltage and current) are found within the STAS limits specific to the potentially explosive coal mines. The next sequence of the algorithm, will give the possibility to monitor different types of parameters (O 2 , CO, Q, t0, etc.) or to monitor the CH 4 concentration for the main areas from a coal mine: the preparation area; the stope area and the niche/gallery area.
Methane sensor output provides a sinusoidal voltage with constant amplitude and variable frequency that has a directly dependent variation with the concentration gas, from the monitored in area. 2.2 Flowchart of the methane gas processing plant Applying the proposed algorithm it is possible to take predictive decisions because the parameters are monitories. The algorithm gives the operator pertinent information about the future evolution of the controlled system. Fig. 2 describes the first sequence of the proposed algorithm in which the condition of methane gas
Figure 2. Synthetic flowchart of the parameters monitoring for hazardous areas When the methane gas concentration exceeds the rated one, the algorithm will display a signaling alert and a switching-off command will be given to the respective area (e.g. for preparation area the concentration threshold is 0.75%; for stope area the concentration threshold is 1.8% and for nice/gallery area the concentration threshold is 0.5%). For every coal mining area a group of 5 methane transducers were implemented, although if the topological structure of the working place imposes their summary can be modified. In order to to maintain the environmental conditions in terms of mining parameters, the algorithm can be modeled in a
ISBN: 978-960-474-316-2
similar way regarding other parameters (O 2 – using the P1 subroutine; CO – using the P2 subroutine and CO 2 – using the P3 subroutine). All processed data are sequentially stored in a digital memory and if no other restrictions appear the algorithm will be resumed from step 0.
3 Virtual instrument for methane gas monitoring Virtual instrumentation, used in hazardous areas, is hardware and software technologies used in order to create flexible and sophisticated instruments for control and monitoring different parameters which
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are important for maintaining good environmental conditions for workers in coal mines. This instrumentation represents a cost effective solution due to software/hardware adaptability and can be easily extended for monitoring others parameters.
3.1 Simulation of the methane gas processing plant using HP VEE software The automation testing system for methane gas monitoring, is presented in figure 3 and and refers to the simulation of a mining processing plant with 3 warning thresholds.
CH4 Transducer
Cycle time
Channel 1 CH4[%]
Threshold 1[%]
Threshold Alarm 1 Alarm Th. 1
Threshold Alarm 2 Switching-off Threshold
Threshold 2[%] Alarm Th. 2
Threshold 3[%] Alarm Th. 3
Figure 3. Graphical interface for CH 4 processing plant simulation with 3 warning thresholds Measuring cycle time shows the period in which the channel sensor is active, which means that methane transducer captures the parameter subjected to diagnose for a predefined period of time. The alarm threshold can be changed according to user requirements.
In this case, the simulation is performed on one channel regarding the CH4 concentration. It can be seen a directly dependence related to V / f, an increase in methane on the virtual meter is correlated with an increase in frequency on on FFT display.
Threshold Channel 1
Threshold Channel 2
Threshold Channel 3
Threshold Channel 4
Switching-off V
Figure 4. Graphical interface for CH 4 processing plant simulation with four channels
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As can be observed, in figure 4, the graphical program contains four CH4 transducers each having a deferent switching-off threshold. Each channel has their own processor for analyzing the information received from the transducer, and each has one delay which records information for a certain period of time, then the program automatically switch to the next channel. In this graphical interface was simulated an exceeding of the CH4 threshold maximum concentration from the channel 1, moment in which the voltage is switched off. Threshold values to which the channels will switchoff are set by the developer. Using the program can be also achieved a history storing for exceeded CH4 evolution for all channels.
3.2 Virtual instrument for methane gas monitoring using HP VEE software and DT data acquisition board A virtual instrument consists of a computer equipped with powerful application software, as Agilent HPVEE as we have used in this applications, cost-effective hardware such as PC plug-in boards, and driver software, which together outperform the functions of traditional instruments for test and automation. For synthetic testing of the mining processing plant it was developed a graphical program which is based on the presented algorithm and a corresponding graphical user interface that enable the display of information regarding the hazardous areas parameters.
Figure 5. Graphical interface for the virtual CH 4 processing plant
ISBN: 978-960-474-316-2
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Figure 5 shows the graphical interface of the program running as coal processing plant with three channels and three alarm thresholds and particularity is the A/D Config block, enables which channels are use for data acquisition, and the sampling rate and gain for each. First of all were selected analog input objects Analog Input Objects, this achieving a complete system configuration, like is shown in figure 6. Using this dialog box is specified all configuration inputs and well as their sampling rates. In order to start analog data acquisition, the A/D Config object must be set to start acquisition automatically when Get Data Function object executes. The virtual instrument Get Data Function collects CH4 data on the specified channels and connects them to the display tools.
Figure 6. Analog input configuration diagram for data acquisition system In order accomplish continuous analog data acquisition a Until Break object was used.
Cycle time
Threshold 1[%]
Alarm Th. 1
Threshold 2[%] Alarm Th. 2
Threshold 3[%] Alarm Th. 3
Figure 7. Graphical interface of CH4 virtual monitoring instrument CH4 gas sensor (whose operation is simulated with a signal generator) and a data acquisition device (DT USB-304) as interface between the circuit and the computer running the acquisition software, data is sampled and analyzed.
Compared to the situation presented earlier this time, in figure 7, is presented a hypostasis where all three warning canals thresholds are "alarmed", i.e. all three have exceeded limits established for the CH 4 concentration. The current voltage characteristic measurements were performed using a virtual measuring tester composed of data acquisition board, an adequate designed interface and the HP VEE software installed on the PC. At a minimum the monitoring processing plant shall stipulate the frequency of the sensor out voltage. In these applications the frequency band of the output signal ranges between 0÷15kHz. The functionality was tested under laboratory conditions. The measurement circuit contains the
ISBN: 978-960-474-316-2
4 Conclusion This work presented a virtual instrument technology for simulating a mining processing plant conducting to a monitoring of the main coal mining parameters, the most important being methane gas. The emission of methane gas is normally diluted within safe limits by the circulated air current, but in order to do this the mine ventilation system must be switched-on by
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atmospheres”, International Symposium, Occupational Health and Safety, SESAM 2011, 5th Edition, INSEMEX Petroşani, Editura INSEMEX, ISSN 1843-6226, pag. 208-215, Sinaia, România, 9-11 noiembrie 2011. [8] D.c. Hovde, J.A. Silver, and A.C. Stanton, “Measuring atmospheric methane and water vapor using near-infrared diode lasers,” SPIE 2112, 110 (1994). [9] Sanguo Li, Yan Zhang , Thomas Koscica, Hong-Liang Cui, Near-Infrared Fiber Optics Gas Sensor for Remote Sensing of CH4 Gas in Coal Mines, Remote Sensing of Aerosol and Chemical Gases, Model Simulation/Assimilation, and Applications to Air, 2006 [10] D. Farhey, Integrated virtual instrumentation and wireless monitoring for infrastructure diagnostics, Structural Health Monitoring Journal, Vol. 5, No. 1, , pp. 29–43, Mar. 2006. [11] Best Practice Guidance for Effective Methane Drainage and Use in Coal Mines, Economic commission for Europe methane to markets partnership, ECE Energy Series No.31. [12] Office of Air and Radiation U.S. Environmental Protection Agency, Technical support document for underground coal mines: proposed rule for mandatory reporting of greenhouse gases, february 4, 2009 [13] Dong Yunhua, Zheng Xianfeng, Design of Coal Mine Comprehensive Parameters Monitoring System Based on DSP, International Conference on Computer Science and Information Technology (ICCSIT), Singapore, 2011 [14] Li, Mo, and Yunhao Liu, Underground coal mine monitoring with wireless sensor networks, ACM Transactions on Sensor Networks (TOSN) 5.2 (2009): 10. [15] R. Dobra, Predictive Diagnose Method for Minimizing Voltage Switching-off Risks from The Mining Power Networks, Revista Minelor, ISSN 1220 – 2053, 2010. [16] Laurentiu Alboteanu, Florin Ocoleanu, Alexandru Novac, Gheorghe Manolea, Remote monitoring system of the temperature of detachable contacts from electric cells, Analele Universităţii din Craiova, seria Inginerie Electrică, Nr. 34, 2010, vol. I, ISSN 18424805, pp. 184-189. Editura Universitaria. [17] Darie M., Burian S., Ionescu Jeana, Csaszar T., Moldovan L., Andriş A, Modern prediction methods in the monitoring process of security parameters, WSEAS Transactions on Systems, Issue 7, Volume 9, 2010.
the processing plant for as many times as needed, in order to keep good environmental conditions for the mining operations. Coal exploitation is still an important source for global energy production (e.g. electrical and thermal energy) for the past centuries and the world will continue to depend on coal as an important energy source in the future. Methane gas released during coal mining creates unsafe working conditions in many underground mines around the world, with human fatalities an unacceptable consequence of many methane‐related accidents. In contrast to CH4 emissions from ventilation systems, no agency requires mines to report the amount of CH4 they drain from degasification systems and because of that the mining processing plant need to measure the ventilation and use appropriate methods for accounting the degasified CH4 [10]. A virtual simulated model of the mining processing plant a graphical program was developed using HP VEE software and by means of data acquisition board DT 304. Highly selective response to CH 4 mining parameter was obtained using U/f methane sensors and thus no longer needed some filtering materials or appropriate delaying circuits. References: [1] Michael Clardy, Research on Virtual Instruments Test System of Coal Mine Environmental Parameters, Degree-thesis. [2] Liu Hong, Huang Chaozhi, Xiao Fayuan, Research on Monitor System of Distant Coal Mine Gas Based on Labview, Lecture Notes in Electrical Engineering Volume 99, 2011, pp 457-461. [3] American Society of Testing Materials (ASTM), 1996. Standard Guide for Soil Gas Monitoring in the Vadose Zone, D 5314-92, Volume 4.09, Soil and Rock (II), 31p. [4] EIA. Annual Energy Review 1997. Energy Information Administration, U.S. Department of Energy, Washington, DC. July 1998. [5] Mousset-Jones, P, A survey of mine ventilation practices, Mackay School of Mines, USA, pp 19, 1986. [6] Bharath Belle, Real-time air velocity monitoring in mines – a quintessential design parameter for managing major mine health and safety hazards, Anglo American Metallurgical Coal, 2013 [7] Tiberiu Csaszar, Dragoş Păsculescu, Sorin Burian, Marius Darie, Jeana Ionescu, Method of assessment for energy limited supply sources, designed for use in potentially explosive
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