Distribution of Heavy Hydrocarbon in Coal Seams and Its Use in Predicting Outburst of Coal Distribution of Heavy Hydrocarbon in Coal Seams and Its Use in Predicting Outburst of Coal

Distribution of Heavy Hydrocarbon in Coal Seams and Its Use in Predicting Outburst of Coal

  • 期刊名字:中国矿业大学学报
  • 文件大小:447kb
  • 论文作者:蒋承林,李增华,韩颖
  • 作者单位:School of Mineral and Energy Resources
  • 更新时间:2020-07-02
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论文简介

Jum.2003Journal of China University of mining technologyVol 13 No. IDistribution of Heavy Hydrocarbonin Coal Seams and Its Use in PredictingOutburst of coalJIANG Cheng-lin蒋承林),LⅠzeng-hlu(李增华), HAN Ying(韩颖)School of Mineral and Energy Resources, CUMT, Xuzhou, Jiangsu 221008, ChinaAbstract: In order to verify whether any special gas component exists in outburst samples or not coal samples froboth outburst coal seams and non-outburst coal seams were collected. Some gases were extracted from the samples andanalyzed qualitatively and quantitatively on chromatogram-mass spectrograph. The qualitative analysis show that thereis no special gases in coal seams. And the quantitative analysis indicates that the heavy hydrocarbon content in coal samoles from outburst coal seams is apparently higher than that from non-outburst district ones which reflects the damageof geological tectonic movement to coal body in history. Therefore, the heavy hydrocarbon content of coal sample canbe used as an index to predict coal outburstKey words: coal and gas outburst heavy hydrocarbon predictionClC number: TD 713 Document code: A Article ID: 1006-1266( 2003)1-0029-06Coal and gas outburst is one of the most harm- coal seam is given, and the reasons are analyzedful disasters in coal mining. The prediction of district coal outburst is of great importance when the 1 Collecting and Sorting of Coal Samplesout burst coal seam is mined. If there is not outburstThe coal samples are collected every 3050 mdanger in some districts mining can be carried outfrom exploited roadway of No 5 coal seam in No 10without taking any measures against outburst othmine of Pingdingshan. During sampling the surfaceerwise, local prediction and measures against out- coal is removed by a sharp-headed hammer so thatburst must be adopted. To forecast coal outburst ac- the fresh coal sample can be taken out. And then thecurately the key is to seek an appropriate predictionsample is put into a bag, with each bag beingindex of outburstmarked with serial numbers collecting time siteIn the 1970s when uSsr made a research ondheavy hydrocarbon in coal seams they found thatThe outburst types of the collected coal samplesthere was a high content of heavy hydrocarbon inmust be ascertained. Dynamic phenomena such asoutburst coal seams. In the 1980s, Yu liangchenoutburst once happened at some places the coaland Li Wenfu, the scholars of fu shun Coal mineSafety Research Institute found that there existedbody in the coal seams is very broken. It is firmlybelieved that the coal samples collected within 300 mthe same rules in coal seams of China. In this paperin the neighborhood of the outburst site are all outthe distribution rules of the heavy hydrocarbon content of No. 5 coal seam in No 10 Mine of PingdingI samples( the first kind ) Some placesshan is measured its out burst critical value of the中国煤化工 h as outhCNMHGgs to non-outburst re-Received date: 2003-03-1Foundation item: Supported by nsFc project 50274067)Biography JIANG Cheng-litd 1956-), male from Huangshan Anhui province, Ph. D, professor engaged in gas outburst and safety produc-万数据meJournal of China University of mining technologyVol 13 No. 1gion. Coal samples collected from there are non-outburst sampled( the third kind ) But the coal samplescollected from those regions between outburst ditrict and non-outburst district are outburst -threatenled( the second kind ) wheples are collected from mine their outburst typeshould be assured on principles above and their collection place should be marked on the contour map ofthe floor. Due to the restriction of the exploitationl10)condition only 21 outburst coal samples 27 non-outburst coal samples and 6 outburst-threateningFig. 2 The chromatogram of heavy hydrocarboncoal samples were collectedfrom coal sampleWhen the water in vacuum tube 9 goes up tothe top turn off the valve d and g and the two-wayvalve b, and turn on the valve F. Thus, the air willinto the vacuum tube 9 rapidly, and compresses in suction tube 12. when the valve d and e is5turned on, the burette 8 will link with suction tube12 thus, thebe will get into brette 8 and be stored thereFig 1 Diagram of degasserThermostatic bath 2. Coal sample potRepeat the above steps and abstract gases for3. Syringe needle A. Thermometer7-8 h, then lift the level bottle 10 and make the5. Vacuum pump 6. Vacuum gaugeliquid level of bottle to the height of burette 8. In7. Desiccator 8. Gas storage tulthis way the total volume V of gases collected from9. Vacuum tube 10, Level bottlethe coal sample can be read. Then pour out the coal11. Gas intake , 12. Suction tubeA BC. two-way valve d E f G. tee valvesample from the pot and weigh it the weight g ofcoal sample can be measure2 Abstraction of Gas from Samples3 Analysis of Gas SamplesThe coal samples was broken first sifted with asieve (p3 mm ), put into coal sample pot, and thenThe purpose of analyzing gas samples is to as-the pot was connected with a degasser( Fig. 1 )for certain the amount of hydrocarbon components andgassingtheir corresponding content in it. The task was carBefore abstracting the gases, start vacuum riedgram-mass spectrograph andpump, open the valve G, D, F and two-way valve SP501 gas chromatograph. The experimental condiC, degas the vacuum tube 9 and the suction tubeons are12 and make sure that the wholeInstrument: GCMS--QP1000 chromatogram-proof, then turn on the valve e and lift level bottleo remove gasesm gas storage tumass spectrograph i SP501 gas chromatographTurn off the two-way valve C, penetrate theChromatograph column: OV-1 25 m X0. 2syringe needle into coal sample pot then put the pot mm capillary chromatograph columninto thermostat 1, open the two-way valve b, and中国煤化工℃heat the pot gradually to 95100C. In this way theCNMHGgases in pot can get into the suction tube 12 throughSample size: 10 mLsyringe needle, two- way valve B and the valve GCarrier gas: He, 25 mL/minchromatogram-mass spectrograph. Because the solvJIANG Cheng-lin et alDistribution of Heavy Hydrocarbon in Coal Seams and31ability of different heavy hydrocarbon is not the condition every separated heavy hydrocarbon is desame in the fixed liquid of chromatograph column tected after getting into hydrogen flame detector itsand carrier gas after a lot of repeated thermody- chromatogram can be obtained( Fig. 2 ) Table 1namics distribution these different heavy hydrocar- shows their qualitative analyzing results. In No. 10bons are separated, and then flow out of the chro- mine of pingdingshan there are about twenty kindsmatograph column in order. After testing them of components in either outburst coal samples orqualitatively on chromatogram-mass spectrograph, non-outburst ones their qualitative results are simitheir components can be determined. When gas lar. This shows that no specific gas component exinjected into SP501 gas chromatograph ists in outburst coal samplewhich has the same chromatograph column and testTable 1 qualitative analyzing results of gas components in Fig. 2Peak numberNameMolecular formula Peak numberMolecular formulaPropaneCaHsIsobutaneisopentanePentane2 2-dimethyl butaneCyclopentane2 3-dimethyl butane2-methyl pentanepentaneHexane122 2-dimethyl pentane2 A-dimethyl pentaneBenzeneCaH3 3-dimethyl hexaneexane3-methyl hexaneHeptaneHQuantitative analysis adopts external standard where: C is the total concentration of some alkanemethod. The ethane is used as standard gas sampleA; is the summation of all isomers peakto make sure that the concentration of each component can be obtainedrelative correction coefcient of each componentBy the above method, the concentration of eachIf As is the peak area of standard gas, fms is its hydrocarbon in gas sample can be calculatedrelative quality emendation factor, M, molecularAccording to the concentration of each hydro-weight, Cs volumetric concentration unit: ppm ), carbon and the total volume V of gases and coalthen when the peak area a of some component is sample' s weight the content of each hydrocarbon inmeasured, its relative quality emendation factor fm, unit weight of coal can be calculated. The formulamolecular weight M, then the concentration of the as followscomponent C can be calculated as follows(3)A、 fms M(1)where: m is the content of some hydrocarbon mg/In the experiment thentration of stardard gas sample( ethane )Cs is 1064 ppm, M,=30C is the concentration of some hydrocarbofms=1. IBecause there are some isomers in every kind ofhe total volume of gases, mLalkane and their relative quality emendation factors中国煤化工of some hydrocarbonare the same if all isomers peak area of an alkaneCNMHGI sample, gare added up, the total concentration of this kind ofAccording to the above method, each kind ofalkane can be calculated by the following formulahydrocarbon content( C3. Cs )in 54 coal samplesms M. C. 2A;,(2) which are taken from No. 5coal seam in the No 10fm M方方数据fmine of pingdingshan have been testedJournal of China University of mining technologyVol 13 No. 1tion from C3 to C8 is quite high in outburst coal4 Data Analysis and Processseam, but it is lower in non-outburst coal seam. TheBecause the hydrocarbons C1 and C2 may es- more the indices are adopted during predicting outcape easily during sampling and testing their test burst coal seam the more complex the computingvalues are unstable. So only the C3 4 c5 C6 C7 process is which can affect its application in the fuand CS contents in coal samples are measured and ture. Now that each heavy hydrocarboncalculated in test. During analyzing, they can be C8 in coal seam can distinguish outburst coal samused as both individual index and combination inoles it is considered that the content summationdefrom C3 to C8 should be taken as a comprehensiveIf the indices to distinguish 21 outburst coal index. When the C3-s data of 21 outburst coal samsamples and 27 non-outburst coal samples in No 5 ples and 27 non-outburst coal samples are substitutedcoal seam of the No. 10 mine in Pingdingshan are in the program of Fig, 3, the distinguishing calculadiscriminant of each kind of index can btion is carried out, the linear discriminant is as feleved and used to distinguish the outburst coal lowssamples from non-outburst ones so that the distinz=0.0205×ggC3-8)(4)guishability of each index can be calculated. It is noSolve AC=Ddoubt that the indices having good distinguishabilityreflect the differences between outburst coal seamOutput discriminant Y=CXand non-outburst coal seam. Therefore, the gascomponents expressed by the indices can be used asOutput the distinguish results otoriginal samples and value ymark gases to predict outburst coal seams"n,②Fig. 3 is the flow chart of the datum-procesDistinguish new sample?program. It is programmed on the basis of FisherGive the results and ydistinguishing analysis method. The data of each"2( u, XPr r a)coal sample showuld be transformed to natural logaS2∑(g4y)Endrithm before analysis. Table 2 shows the distinA A"S,+sguishing analysis resultsFig 3 Program diagram of processing datable 2 Distinguishing analysis result of No 5 coal seamHere, the discriminant coeffic0.020507C8CMisjudgedits critical value is e0.1377. If the content5221686154value of any coal sample( unit: mg/g) is substitutedU/。54.26.783387.568.7591.7in formula( 4), its value of z can be got. If 2>the coal sample belongs to outburst one if 2 < zoTable 2 indicates that each index can be used to the coal sample belongs to non-outburst onedistinguish outburst coal samples and non-outburstThe difference between the indices of outburstcoal samples. But the distinguishability of each in- coal samples and non-outburst coal samples can bedex is different. When each index is put together to discriminated by the F test. In the above calculaform a combination index their distinguishability tion, the testing value F was 22. 26, the criticalincreases greatly. When the combination indices areMn,+A-1)=F2(1A6)Ifdopted in No 5 coal seam, the sample number mis- thel中国煤化工).05,F0.0(146)=4judged is only 4, its distinguishability reaches 91CNMHGe chart of f distribu-7%, which shows each index from C3 to C8 can be tion, which is lower than F( 22. 26 ). Thus it can bestinguish outburst coal samples and nonseen that between above two kinds of collectivitypal samples and each kind of hydrocarbon there is a notable difference at the level of a=0. 05can be seet方数振 mark gas. The content summaIf the distinguishing result by the linear disJIANG Cheng-lin et alDistribution of Heavy Hydrocarbon in Coal Seams and33criminant is contrasted with the original classifica- bution of Cr-s in No 5 coal seam increases generallytion of these 48 coal samples the misjudged number with the depth of coal seams. Furthermore at thoseis 9, then the distinguishability of the above linear sites where some dynamic phenomena exist thediscriminant is as followscontent summation of C3-s is quite high and form81.25%nomenon dose not exist, the content summation ofThe above distinguishing result shows that theCs-o is lower. At those regions far from the measurdistinguishability also readaches to 81. 25% when C38 ing points where the Ca-g distributes gently andis adopted as the distinguishing index. Although itsthe distribution is deduced by the data of samplingdistinguishability is a little lower than that of combilocation. So this result is not very credible. If thenation index. C-s is the content summation fromcoal of these regions can be sampled and analyzed ,itC, to cs and can be calculated and applied very con-can be proved that the C3-s's distribution is similarveniently. So it can be used as a regional forecastinto that of sampling regionsindex in No 5 coal seam of the No. 10 Mine inPingdingshan5 Result Analysiecause the comprehensive index Ca- is theAccording to the research of outburst mecha-only distinguishing index the discriminant critical nism in the last decades coal and gas outburst is thevalue zo in equation (4 can be expressed by the result of synthetic action by crustal stress gas pres-from C3 to Cs, that is, zosure and coal strength. The outburst danger of each0.00121 mg/g. In practical application only the point in coal seam is different, which has a characcontent summation C3-s )of coal sample taken from teristic of regional distribution. Although outburstcoal seam should be tested and then compared withmay occur at those zones with simplec struczo, the coal seam can be distinguished as outburst ture, many typical coal and gas outbursts occur atcoal seam or non-outburst coal seam. If its content those zones with fractured structure. The reason issummation( C3-s )is greater than the critical value, that the intensity of coal seam decreases greatly afterit belongs to outburst coal seam and vice versasuffering from crustal movement especially in somelue of 54 coal samples enclosed regions where the coal body has already hadtested in No. 5 coal seam and their relative coordi- a serious geologic breakage but with a good conditionnate data, the distribution chart of C3-g can be for storing gasses When mining workingdrawn( see Fig 4). In Fig 4, the unit of C3-g is these geologic structure region coal and gas out-ug/gburst may haerefore the oudanger in coal seams relates closely to geologic struc-ture region and shows different distribution in difActual coal seams are formed by archaic plantremains under the condition of high temperature andpressure. According to the findings of coal chemistry, general coal molecules are macromolecularWH中国煤化工 Her the action of geolcCNMHG compressive-shearingFig 4 distribution chart of C3-s in No 5stress or compressive-torsion stress the intact coalcoal seam of the No 10 Mine in Pingdingshanbody becomes cracked. Owing to the mechanicalFro数据 we can see clearly that the dibreakage some covalent bonds in big coal moleculeswill break and some hydrocarbon with lower molecJournal of China University of mining technologyVol 13 No. 1ular weight will be formed. This process is called graph there are about 20 compounds of heavy hymechanical degradation process in organic chemistry drocarbone coa seamo special compoand geology The greater the function of geologic nent exists in the outburst district of coal seamstructure is the more broken the coal body is And2)By distinguishing and analyzing the testingthe more obvious the mechanical degradation is the data of 21 outburst coal samples and 27 non-outburstmore the hydrocarbons of low molecule are formedcoal samples it has been found that the content ofAfter these heavy hydrocarbons are formed they each heavy hydrocarbon( C,, C4, Cs, C6, C7, Cs )incan be easily absorbed and stored by coal body be- coal seams is related to the out burst coal body.cause they are similar to coal molecules in structure3)When the Cs( the content summation fromTherefore, in the same coal seam the amount of C3 to Cs )is adopted as the comprehensive index ofheavy hydrocarbons at different positions somewhat district outburst forecast its distinguishability canreflects relatively the strength of coal body. If the reach 81.25%. Here outburst critical value is zogas pressure and crustal stress have not changed in 0. 00121 mg/g. When the C,-- of some coal samplethe coal seam it reflects directly the outburst danger taken from site is greater than zo the region whereof coal body. It is feasible that the heavy hydrocar- the coal sample is taken belongs to outburst regionbon is adopted as an index to proceed district forecast otherwise it belongs to non-outburst regionof outburst danger in coal seam. The test results of4)The distribution chart drawn by the contentheavy hydrocarbon in No 5 coal seam of No. 10 summation of Ca-s in 54 coal samples of No 5 coalMine in Pingdingshan indicates that the content seam indicates that the content summation of C3-gissummation( C3-s )is higher at the place where dy- in accordance with the regional distribution.Atnamic phenomenon exists and the content summaphenomenon exists, theior( C3-s )is lower at the place where dynamic phe- content of Css is quite high; but at the sites wherenomenon does not exist which explains this analysis there is not any dynamic phenomenon, the contentcompletely6 Conclusions5)The content of C3- at any position in coalseam is the result of geologic structure movement r1)By testing qualitatively the coal samples its amount reflects the strength of coal body, and sofrom the No. 5 coal seam of the No. 10 Mine in it can be used as an comprehensive index of regionalPingdingshan with chromatogram-mass spectro- outburst forecast in coal seamReferences[1]李文馥.煤层瓦斯组分的研究J]煤矿安全1988(9):4[2]俞启香矿井瓦斯防流M]徐州冲国矿业大学出版社1992[3]于不凡.煤和瓦斯突出M]北京:煤炭工业出版社1985[4]孙传经.气相色谱分析原理与技术M]北京北学工业出版社A981[5]林少宫,袁蒲佳申鼎煊.多元统计分析及计算程尻M]上海华中理工大学岀版社,988H中国煤化工CNMHG

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