Research on lift pressure system with combined pipeline and intensive drill⁃hole gas drainage along the layer in low permeability coal seam
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Graphical Abstract
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Abstract
Aimingattheproblemofgaspre⁃drainageinhighgasandlowpermeabilitycoalseam,the strengthentechnologyofcoalseamgasextractionwasputforwardwhichisthesystemofcombinedpipe⁃ linetoliftthenegativepressureandintensivelargediameterdrill⁃holealongseam*Theextractionprin⁃ cipleofrealizingthepermeableincreasinginallzonebyintensivelargediameterdrill⁃holealongseam wasexplained*Accordingtothecontinuityliquidflowequationandenergyequation,theexpressionof liquidenergychangeswasestablishedtogetliquidenergygradientlinesinsectioncompetent pipe⁃ line*Combinedwiththe“negativepressure⁃flow”characteristiccurveofpre⁃drainagegasdrill⁃hole,the mechanismofincreasethenegativepressureandextractionscalarthroughcombinedpipelinewasclari⁃ fiedandtheparametersofstrengthenextractiontechnologyincoalseamwasconfirmedbypracticalex⁃ perience*Thepracticeshowedthatthistechnicaleffectongovernancegaswasremarkable,thegasex⁃ tractionrateinworkingfacewasabove55% andtheproductioncapacityincreasedfrom1*2Mt/ato 1*8Mt/a*Theuppercornergasconcentrationwasunderthesafetystandard,andthusthesafetyandef⁃
ficientlyminingincomplicatedgeologicalconditionswasrealized*
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