Adding gas from biomass to the gas grid - SGC

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4.3.6 Cryogenic removal of carbon dioxideCarbon dioxide can be separated from methane by cooling the gas mixture at elevated pressureand removing the formed liquid carbon dioxide. This method has been studied as a research projectat the Lund Institute of Technology, but is not available as a commercial process.The crude biogas is compressed to approximately 80 bar. The compression is made in multiplestages with intercooling. The compressed gas is dried to avoid freezing in the following coolingprocess. The biogas is cooled with chillers and heat exchangers to -45 °C. Condensed carbondioxide is removed in a separator. This carbon dioxide is processed further to recover dissolvedmethane which is recycled to the gas inlet.The gas is cooled further to approximately -55 °C by heat exchangers. The cold gas is expandedthrough a Joule-Thomson nozzle into an expansion vessel. The pressure in the vessel is 8-10 barand the temperature approximately -110 °C. In the expansion vessel a gas-solid phase equilibriumis established. The solid phase is frozen carbon dioxide. The gas phase, which consists of morethan 97% methane, is heated before it leaves the plant (see figure 9).No cost data are available on investment and operational but calculations made in the researchproject indicate that the costs are comparable with water scrubbing techniques at medium sizeplants. The cryogenic process benefits economically from larger plants more than water scrubbingprocesses do. Thus, a large upgrading plant based on cryogenic technique would have a lower costthan the same size water scrubbing plant.1412Heat exchanger5Heat exchanger6611J-TnozzleF1B12B23Heat exchanger2Heat exchanger318 19Heat exchanger44KA16KOND 1CO2 outBIOGAS21175F2Biogas inGas drierMETHANEHeat exchanger1KOND 2CO2 outUpgraded gas outFigure 9: Cryogenic removal of carbon dioxidepage: 45
Parameter Unit ProcessCapacity range m 3 biogas/h 100 - 20,000Input· methane· carbon dioxyde· nitrogen· hydrogen sulphideOutput· methane· carbon dioxide· dewpointProcess conditions· Pressure after compressing· Pressure after expansion· Condensing temperature%%%ppm%%°C at 8 barbarbar°CTable 17: Cryogenic removal of carbon dioxide45 - 7525 - 55< 1< 5> 97< 3- 110808 - 10- 1104.4 ADDITION OF PROPANEPropane or Liquefied Petroleum Gas (LPG), which is a mixture of propane and butane, has a highcalorific value and Wobbe index. With a typical LPG composition of 70% propane and 30% butane,the net calorific value is 102 MJ/m 3 , and the gross Wobbe index is 85 MJ/m 3 . Therefore, addition ofLPG to the biogas will increase these properties for the mixture towards the specifications ofpipeline quality gas.However, addition of large amounts of LPG is a rather costly upgrading method and it is notpossible to obtain typical pipeline specifications by simply adding propane to the biogas. As anexample, the relative density of biogas (65/35% CH 4 /CO 2 ) and LPG is approximately 0.9 and 1.7respectively. Such a high density is outside conventional quality requirements.LPG addition can, however, be used as a supplementary method that can be combined with otherupgrading methods. Following the main upgrading process, propane addition can be used toregulate the gas quality towards pipeline quality, and thereby compensate for variations in thecomposition of the upgraded biogas. The major advantage of supplementary propane addition isthat the main upgrading process can operate with lower outlet methane concentrations. For someupgrading processes, e.g. membrane separation, this means that higher efficiencies/methane yieldscan be obtained.The required amount of LPG addition depends on the main upgrading process, the pipelinespecifications, the biogas quality etc. As an example, the energy content of the estimated LPGaddition in combination with membrane separation corresponds to approximately 8% of the total gasflow. Table 18 shows some financial data for this propane addition installation at different biogasflows (400 and 1600) [lit.15]. The investment for this corresponds to approximately 10% of the totalinvestment of the upgrading plant.page: 46
Page 1 and 2: Report SGC 118Adding gas from bioma
Page 3 and 4: CONTENTS1 INTRODUCTION 32 IMPORTANC
Page 5 and 6: 2 IMPORTANCE OF ADDING GAS FROM BIO
Page 7 and 8: Incentives by eco-labelingBy adding
Page 9 and 10: is mixed with coal in a combustor p
Page 11 and 12: Comparing efficiency data is a diff
Page 13 and 14: Figure 1: Energy flow diagram and i
Page 15 and 16: The product revenues are the most u
Page 17 and 18: 3.1.2 Survey of technologiesThis pa
Page 19 and 20: 3.1.3 Table of biogas compositionsD
Page 21 and 22: Aspect Unit ValueManure M 3 /day 6B
Page 23 and 24: Technologies for syngas upgradingTh
Page 25 and 26: CompositionProcesscalorific value M
Page 27 and 28: 4 PIPELINE QUALITY GAS FROM BIOGAS4
Page 29 and 30: Removal of hydrogen sulphide with m
Page 31 and 32: Parameter Unit Process Plant exampl
Page 33 and 34: Parameter Unit Process valueCapacit
Page 35 and 36: 600.9500.840Wobbe index [MJ/m 3 n]R
Page 37 and 38: Figure 4 illustrates reported inves
Page 39 and 40: 4.3.4 Upgrading by absorption of ca
Page 41 and 42: Removal of carbon dioxide by water
Page 43 and 44: Selexol from the flash tank is depr
Page 45: poisonous and aggressive liquid wit
Page 49 and 50: gas system is maintained by a contr
Page 51 and 52: In the gasification process the fir
Page 53 and 54: A catalytic process requires a feed
Page 55 and 56: In all countries gas in a distribut
Page 57 and 58: 6 SUPPLYING GAS FROM BIOMASS TO THE
Page 59 and 60: In Europe only two kinds of natural
Page 61 and 62: Component or quality Unit Limit or
Page 63 and 64: The directive thus also provides po
Page 65 and 66: Figure 13: Maximum range of permitt
Page 67 and 68: Figure 16: Wobbe index for differen
Page 69 and 70: 6.2.5 Discrepancies between standar
Page 71 and 72: 6.2.7 Description of national or de
Page 73 and 74: Figure 17:Arrangement of the contro
Page 75 and 76: Measurement methodDetection tubes f
Page 77 and 78: Descriptioncalculation of propertie
Page 79 and 80: The possibility of adding off-spec
Page 81 and 82: Europe among countries relying on e
Page 83 and 84: 7.1.3 FinlandBiogas is mainly produ
Page 85 and 86: Figure 18: Distribution of capacity
Page 87 and 88: Calorific Availability Market price
Page 89 and 90: Many landfills are equipped with ga
Page 91 and 92: the type and volume of the respecti
Page 93 and 94: 7.2.4 FranceThere are currently no
Page 95 and 96: 7.2.7 SwedenBiogas as a fuel for ve
Page 97 and 98:
Policy on renewable energyThe gener
Page 99 and 100:
Danish energy policy is to contribu
Page 101 and 102:
Carbon dioxide taxApplication€/to
Page 103 and 104:
CHP FundThe CHP Fund is an incentiv
Page 105 and 106:
Taxation and incentivesFeed-in tari
Page 107 and 108:
Subsidies and fundingThere are seve
Page 109 and 110:
Figure 20:Impact of the energy tax
Page 111 and 112:
TargetsParallel with the target on
Page 113 and 114:
Sweden has no actual program dedica
Page 115 and 116:
Swedish energy taxesThe Swedish ene
Page 117 and 118:
8 CONCLUSIONS AND RECOMMENDATIONSCo
Page 119 and 120:
14 Upgrading Landfill Gas to Natura
Page 121 and 122:
46 ISO 15971: “Natural gas - Meas
Page 123 and 124:
APPENDIX 1:DefinitionsBiogasBiomass
Page 125 and 126:
fixed bed gasification: BIONEERProc
Page 127 and 128:
Final cooling is accomplished by me
Page 129 and 130:
used for direct drying applications
Page 131 and 132:
fluidised bed gasification:EISENMAN
Page 133 and 134:
fluidised bed gasification:SELTECpr
Page 135 and 136:
The Battelle biomass gasification p
Page 137 and 138:
Primary heat exchangerThe primary h
Page 139 and 140:
active coal filter and cooled. The
Page 141 and 142:
• Kärnten (Austria)pyrolysis:Pro
Page 143 and 144:
Quality Value UnitComponents• Car
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Adding gas from biomass to the gas grid - SGC

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