Control of combustion area using electrical resistivity method for underground coal gasification

International Journal of Mining Spence and Technology 22(2012)351-355Contents lists available at SciVerse Science DirectInternational Journal of Mining Science and TechnologyELSEVIERournalhomepagewww.elsevier.com/locate/iimstControl of combustion area using electrical resistivity method for undergroundcoal gasificationSelivanova Tatiana, Grebenyuk Igor, Belov AlexeyFar Eastern Federal University, Vladivostok, Russian FederationARTICLE IN FOA BSTRACTnderground coal gasification(UCG) is one of the clean technologies to collect heat energy and gasesin an undergrou知5Dm2mr2nailable online 15 May 2012Underground coal gasificationonElectro conductivityWhile burning coal spes meb borato ystem (ABMN)of direct and low-frequency current femnas monitoesistance method was used for laboratory resistivity measurement of rock saCoal speccoal electro conductivity hased multistage type of change. Electrical resistivity method is expected to be a useful geophysical toolo 2012 Published by Elsevier B V. on behalf of China University of Mining Technologyollution and well collapse. So, one ofost important UCGsAt the moment, Underground coal gasification(UCG)is one of coal seams and rock masses. The monitoring of thewith zero emission [1,2]. bustion area isfficient gas productiocoal gasification provides pollution control espe- but also for estimation of subsidence and gas leakage to the sur-face[ 1]. Control of the combustion area around gasification cavitych disposal after coal [1, 3 UCG is an alternative for is necessary for UCG safeguardingducted underground in the virgin coal seam, thus largely reducing be used for UCG [10] Coal of far-eastern deposits of Russia contaional mining technology. In fact, UCG is regarded as the most kaolin, illite), iron disulphate(pyrite ), carbonates(siderite, ankeriteon by gasifying un-mineable thin or deep coal seams under diffAlthough modern sensing and control techniques reduce UCG's coal filling cracks and plant tissue vesicle Calcite and siderite arefracture activities can cause gas leakage to the中国煤化工 andomly distributed in coal volCorresponding author, Tel: +7 4232 316294TYHCNMH GWas arups o- 40 g high-asbndress selivanova demail ru(T. Selivanova)and specihc weight ot 1-1.7 g/cm2095-2686s-see front matter o 2012 Published by Elsevier B.V. on behalf of China University of Mining TechnologySeirvanova et al /Intermational Joumal of Mining Science and Technology 22(2012)351-355must be seen as heterogeneous system composedThe coal specimen N1(approximately 18 cm x 36 cm x 22 cm.rotational form)was sampled from the top commercial seam ofovskoe brown coal deposit( Figmorphic phases and petro graphical composition coriginal color of the sample was brown, The sample had horivaried widely changed from even flathod, isogenUCG combusutlying comating19.17.18width was 0.05-0.5 cm. The coalumpled and it fell too applicability check of electro conductivity method for mon- under weak mechanical pressure. Factor of general fracturinSci18 cm x 36 cm x 2oretical analysis and laboratory Pavlovskoe brown coal deposit(as shown in Fig. 2) This specimensimulation tests. Typical results of the laboratory experiments differsof fracturing. Factor of general fracturing of the coalN1, 2(PavlovskoeUCG simulation tests were made in the UCG laboratory of the seam of Urgalskoe coal deposit. The specimen hasFederal University in Vladivostok(the25 cm x 35hown in FiOriginal color of the specimen was bright black with metalliThis experiment was undertaken to indentifyvity activity on the coal samples to set up fundamentnant forms of cleavages wero orthogonally related planes. Domi-on for the technology engineering to evaluate the localof general fracturing of coal specimen was 2deposit(Pavlovskoe deposit, Primorskiy region, Russian Far Eastand coal deposit(Urgalskoe deposit, Khabarovskiy region, Russiannt lines transformation on"coal sample-air"boundary中国煤化工CNMHGFig 1. Coal specimen NI sampled from Pavlovskoe brown coal deposit.2 Coal specimen N2 sampled from Pavlowskoe brown coal deposit.tegrated chemical composition of far eastem coal316-75.7109370.5-6414-.557=840.5-2启Fig 3, Coal specimen N3 selected from Urgalskoe coal deposit2.2 Simulation test of UcGA scheme of the UCG model gasifier used for these tests isFig. 5. Experimental setup for coal specimen.hole, which can be used for moving the oxygen supply from 3 to 12 cm, MN line-from 1 to 2 cm. Cuprous electrodes toand gas production.0.9 cm diameter and 15 cm long were used. Fig. 5 presents the3. Experimental setupand cur-rent measulwere made. The following wilogy of rock sam- mula was used for resistivity exten.les system R=KU/current electric resistanceethod is used for laboratory resistivity measurement of rock where K is the electrode system coefficient: U the potential differ-nce at the receiving circuit, MN: J the current intensity at the circuit feeder ABinciple Vertical electrical sounding was made to determine the 2.4. Gas supplyoptimal size of the electrical system. Size of AB line was changedAn electrical source was switched on to ignite the coal. Afterforward and along the coal seam. The gasifying agents, air and oxgen, were supplied by an air compressor. The gas produced byferred the data of measured potential (voltage ) current were trans.to the control computer for real-time monitoring.中国煤化工CNMHGesistivity activityeating and combustion coal sampleresistivity change during heating andSehivanovg er af /Mntemanonad foumal of Miming Sence and Technoiog 22(2012)351-355slow decreased during heating(the resistcating time was not自qgm可时 pots and, as conseThe specimen N3 was heated for 4 h until 600-800. Stable pro-cess of UCGduring heating and combustion test N3. The resultresistivity of this specimen changed chaotica3.2. Discussion remarksObtained experimental results let us assume that electro conductivity activity during heating and combusting test of coal spFis. 6. Resistivity activiry during heating and combustion test (the brown coal imen depends on normal water content value. Coal combustion zone: (c)Water vapor condensation;(d)Conducting channelingtivity isved Resistivityarameters: (a)Porosity factor: b) Electrical channel convolutionr) Double electrical layer conductivity and solution conductivity4 Conclusionscated multistage type of change. Resistivity decreasing of browntemperaturpansion of mineral spots andg030.020and electrical resistivity activity of coal specimen was noresistivity monitoring technology for evaluation of theground combustion areaFlE& Resistivity activity during heating and combustion test (the coal specimen Acknowledgementson was provided by the Ministry of Educatiorand sciencussian Federation(No. P1679) Far Eastern Federalhe results show that for the first i5 min from the start of heating University. The authors gratefully acknowledge their suppor「中国煤化工CNMHG:sWmm实Liu s u L Mei MDin M in Fecund er: 12141460 -72m underground coAt opposed to the specimen NI the specimen N2 had bigger 15 Kreymin ev Non-conventional terminal technologies of hard quarry fuelspecific weight and smaller degreT, selivanova et al/International joumal of Miming Science and Technolo 22(2012)35I-355200KerdH, Fundamental experimet(101 Kondyrev BL Belov Av, Grebenyk IV Underground coal gasification perspective05 189- wei C, feng e. chin Univ如mm2D2aH中国煤化工CNMHG