沼气技术

BiogastechnologyinchinaZhiyingYanStudentnumber:174Chengduinstituteofbiology,CAS1.Theconceptionofbiogaswhat’sthebiogas?Itisoriginallycalledswampgasjustbecausepeoplefounditinswamparea.Also,itisbecalledbiogasduetoproductionofthisgasbybiologicalmetabolismunderanaerobicconditions.2.Thefermentationofbiogasandits’composingBiogasfermentation,widelydistributedinthenature,isthebioconversionprocessbywhichorganicmatterisdegradedandconvertedintoinflammablegasbymanykindsofmicrobesatanaerobicconditions.Fermentationmaterialsisveryavailablesuchashumanorlivestock’smanure,straw,wastewaterandwasteresidualsfromfactories.Its’maincomposingismethane(CH4),whichcontentis55-70%.Then,itiscarbondioxide(CO2),whichcontentis30-45%.Thereisstillalittlenitrogengas(N2),hydrogengas(H2),sulfuratedhydrogen(H2S),andsoon.Sobiogastechnologycannotonlytreatorganicwastesbutalsogetakindofcleanandrenewenergy.3.MainbiogastechnologiesinChina3.1Householdbiogastechnology“Onedigesterandthreetransformations”modes“Fourinone”modes“Pig-biogas-fruit”modes“Fivetransformations”modesHouseholdbiogastechnology(1)TypicalhydraulicpressuredigesterinChinaFigure1DiagramschemeofhydraulicpressuredigesterThedigesterisasshowninthefollowingFigure1.Beforebiogasgeneration,theliquidleveloffermentationchamberisflushwiththoseofinletpipeandhydraulicchamber.Withthegradualincreaseofbiogasinfermentationchamber,thegaspressureincreasesandpushfermentationchamberliquidtohydraulicpressurechambertillinnerbiogaspressureandouterhydraulicpressuresareinbalance.Withtheconsumptionofbiogas,thebiogaspressuredecreasesandthehydraulicchamberliquidflowsbacktothefermentationchambertoreachanewbalance.Storageanddischargeofgasareperformedbycontinualchangesintheliquidlevelofthepool.Chinesehouseholdbiogasdigestertypeare“round,smallorshallow”,thegeneralvolumeis6~10m3.themainstructureareconcrete,brick-and-concrete,brick-and-mudprefabricationandglassfiberreinforcedplastic,moreovertherearealsosemi-plasticandsoft-bodiedstructure.(2)“Fourinone”modesFigure2Diagramschemeof“Fourinone”modesConstructingsunlightgreenhouseinpeasanthouseholdcourtyard,constructingundergroundbiogasdigesterinthegreenhouseend,constructingpighouseandlatrineabovethebiogasdigester,plantingvegetablesandfruittreesinthegreenhouse.ItsstructureisasshowninFigure2.Inthismode,ittakesthesolarenergyasthepowerandtakesthebiogasasthelink,tocombineplantingandbreeding,whichnotonlyformingecologypositivecycle,butalsoincreasingincomeofChinesepeasantry.(3)“Fivetransformations”modesFigure3Diagramschemeof“Fourinone”modesThismodeisconstructedby5partswhicharebiogasdigester,latrine,solarenergywarmsphere,waterstoragepitandorchardirrigationfacilities.Biogasdigesteristhecorepartof“fivetransformation”energysourceecologymode,wecanintegratetheruralproductionfertilizerconsumptionandtherurallivingenergyconsumptionthroughthelinkfunctionofhighefficiencybiogasdigester,forming“herd—biogas—fruit”inter-acceleratingpositiveecologycyclesystem.ItsstructureisasshowninFigure3.(4)“Pig-biogas-fruit”modesFigure4Diagramschemeof“Pig-biogas-fruit”modesTakethepeasanthouseholdasthebasicunit，usingthelocationsaroundhouses,suchashillyarea,watersurface,courtyardetc.,toconstructlivestockandpoultryhouses,biogasdigesterandorchardetc.,meanwhileintegratingbiogasdigesterconstruction,livestockandpoultryhousesandlatrine,toconfigurate“breeding—biogas—planting”courtyardeconomymode,formingtheecologypositivecycle.ItsstructureisasshowninFigure4.(5)“Onedigesterandthreetransformations”modesToconstructbiogasdigester,meanwhilereconstructingstockandpoultryfeedinghouse,sanitarylatrineandkitchen.KitchentransformationLivestockhouseandlatrinetransform3.2LargeandmediumbiogasplanttechnologyLargeandmediumbiogasplanttechnologyismainusedastreatinghighconcentrationorganicwastewaterinlivestockandpoultrybreedingfarm,breweryandsugarrefineryetc.Largeandmediumbiogasplantincludes:livestockandpoultrybreedingfarmbiogasplant,treatingindustrialorganicwastewaterbiogasplant.3.2.1Processesoflargeandmediumbiogasplant(1)LivestockandpoultrybreedingfarmbiogasplanttechnologyThecurrenttreatmentmeasurestowastewatercontainingdungandstaleinlivestockandpoultrybreedingfarmistakenbiogasplanttechnologyascore,notonlyrecyclingenergysourceandqualifiedorganicfertilizer,butalsotreatingsewageandwastetostandarddischarges.ItsprocessflowchartisasshowninFigure5.Figure5Processflowchartoffarmbiogasplant(2)IndustrialorganicwastewaterbiogasplantFigure6Processflowchartoforganicwastewaterbiogasplant3.2.2TypicaldigestersinbiogasplantFigure7DiagramschemesofCSTRandUASBFigure8DiagramschemesofUSRandAFFigure9DiagramschemesofFBR