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TANYA BANSAL 2012A1PS500G MALAVIKA NAIR 2012A1PS462G
PRODUCTION OF SYNTHESIS GAS BY UNDERGROUND COAL GASIFICATION
Definition:Process of producing syn gasa mixtureCH4,CO,H2,CO2 and water vapor from coal andwater, air and/or oxygenWhy is it important? Coal Reserves:18 trillion tons Coal Gasification & Its Importance
World Coal Reserves
Surface Gasifiers Moving Bed Reactor Entrained Bed Reactor Fluid -bed reactors
Underground Gasification Technology
Methods to gasify coal
UNDERGROUND COAL GASIFICATIONConversion of coal into synthesis gas In-situ gasification process Extracted through a well Utilised for power generation Feedstock in the production of liquid fuels, fertilisers, or other chemical products
UCG Process
Advantages of UCGInaccessible coalsLower Capital costs Avoid Mining problemsRelevance in Indian ScenarioCoal depth and quantity
UCG Technology
Mining technologies :FCL Forward Combustion LinkingRCL - Reverse Combustion LinkingCRIP -Controlled Retraction and Injection PointUCG
Process parameters :Operating pressureCoal reactivityOutlet temperature and flow Governed by the coal and rock properties that vary with time and locationThe UCG Process
Burning - Pyrophoric Silane / propaneChemical Process
PARAMETERS FOR UCGDepth:30580 mThickness: 25 mAsh: 234%Moisture :735%Volatile matter :2744% Fixed carbon:1238%
UCG Reactor(Coal)Liquid Gas separationSteamAir/OxygenUCG GasGasesClean gasFiltration of gasesAcid gas removalSlagPROCESS OF UCG
123456
7891011SteamWater
SURFACE PROCESSRemoval of Slag:Particulates present along with tar and unreacted carbon and hydrocarbonsVapour liquid separatorCyclone separator, Electrostatic separators etc Acid gas removal:Absorption in Methyldiethanolamine(MDEA).Solvent regenerated in stripping section and re-used
Filtration:Solid impurities removedGas heated above dew point
Coal AnalysisBasis : Kalol (Gujarat)Type Of Coal : Bituminous and Sub-Bituminous Depth= 1200 m Thickness=25 m
Proximate Analysis% Mass fractionMoisture (% M)15Ash13Volatile Matter (VM)40Fixed Carbon (FC)32
Formulae:%C = 0.97C+ 0.7(VM - 0.1A) - M(0.6-0.01M) %H = 0.036C + 0.086 (VM -0.1xA) - 0.0035M2 (1-0.02M) %N = 2.10 -0.020 VM
Ultimate Analysis% Mass fractionC51.38H3.92895N1.3S1.5O12.59105Moisture15Mineral14.3
REACTIONS
Reaction Reaction No.C + O2 CO21C + CO2 2CO2C + H2O H2 + CO3C + 2H2 CH44CO + 1/2O2 CO25H2 + O2 H2O6CO + H2O CO2 + H27
Gasification ZonesOxidation ZoneReaction 1Reaction between oxygen and carbon producing heatReduction ZoneReaction 2,3,4Methanation occurs under catalytic actionDry distillation ZoneDewatering and crackingCO2 and H2O separated outCoal contracts
THERMODYNAMIC DATA
ReactionTemperature (K)Equilibrium constant (Keq)Conversion (X)114232.146 * 10140.25(assumption)210737.380.276310737.380.73648730.6060.6155238.22* 10210.36865233.33 * 10410.44378234.950.805
MASS BALANCE
ASSUMPTIONSAll reactions attain equilibriumReactions occur in series order from 1 to 7H2O / O2 ratio for inlet gas: 2C/ O2 ratio =2N2 neglectedBasis= 155000N m3 of UCG GasPressure=4.8 atmPorosity=1%Bulk density of coal =1.2 g/cc
UCG GAS COMPOSITIONMass of slag in product = 12062.4 g/ 155000 N m3 of gasGas outlet temperature = 200-300 CVolume of coal bed= 70709.7 m3Coal gasified = 48631.49 kg per 76810.59 kg of coal
ComponentsMole %Ideal Range %CO240.791312-28CO6.00672-16H228.089711-35H2O16.7956-O22.7303-CH44.76721-8H2S0.81910.03-3.5
Stream 1Temperature =200 CPressure = 4.8 bar
ComponentMole fractionFlow rate(mole/h)CO20.4079138350.399CO0.0600671229.633H20.2808975750.251H2O0.1679563438.232O20.027303558.9205CH40.047672975.8949H2S0.008191167.6782SLAG-607.9965
Stream 2Temperature = 150 C
ComponentMole fractionFlow rate(mole/h)CO20.4079138350.399CO0.0600671229.633H20.2808975750.251H2O0.1679563438.232O20.027303558.9205CH40.047672975.8949H2S0.008191167.6782SLAG-607.9965
Stream 3Temperature = 90 CPressure = 1 bar
ComponentMole fractionFlow rate(mole/h)
CO20.4733878350.4CO0.0697081229.63H20.3259835750.25H2O0.029237515.7348O20.031685558.921CH40.055324975.895H2S0.009506167.678SLAG0.0051791.19948
Stream 4Temperature = 90 C
ComponentMole fractionFlow rate(mole/h)
CO2--CO--H2--H2O0.849742922.497O2--CH4--H2S--SLAG0.15026516.797
Stream 5
ComponentMole fractionFlow rate(mole/h)
CO2--CO--H2--H2O0.84974412.588O2--CH4--H2S--SLAG0.1502672.9596
Stream 6Temperature = 90 C
ComponentMole fractionFlow rate(mole/h)
CO20.4766678350.4CO0.0701911229.63H20.3282425750.25H2O0.031905558.921O20.055707975.895CH40.009572167.678H2S0.00416572.95958SLAG0.023552412.5879
Stream 7Stream 8Temperature = 90 C
ComponentFlow rate (Mole/h)Mole fractionLean MDEA17868.7-
ComponentFlow rate (Mole/h)Mole fractionRich MDEA17868.70.98623H2S166.0010.00747CO24175.20.18799
Stream 9Temperature = 90 C
ComponentMole fractionFlow rate(mole/h)
CO20.316884175.2CO0.0933221229.63H20.4364125750.25O20.042419558.921CH40.074065975.895H2S5.54E-050.7296SLAG0.00553772.95958H2O0.031313412.5879
Final Gas Temperature = 90 CPressure = 1.6 bar
ComponentMole fractionFlow rate(mole/h)
CO20.242824175.2CO0.093841229.63H20.438845750.25O20.04266558.921CH40.07448975.895H2S5.6E-050.7296SLAG--H2O0.03149412.5879
ENERGY BALANCE
Enthalpy of Reactions
Reaction no.Temperature(K)Enthalpy ,Reaction Temp(kJ/mol)11423-98.23942107337.355523107356.100134873-7.854825573-85.5136573-24.4277823-15.2091Total Enthalpy-137.788
Enthalpy for 1 mole of carbon =-137.788 kJThe enthalpy for 10915.56/hr moles of carbon = (-137.788 * 10115.56)= -1504030 kJ/ hr
Energy for steam formationHeat for formation of 101915.6 moles/h of steam:Q= mCp (100-25) = 10195.6 * 18 * (1.864+1.94) *0.5* 75 = 28027.896 kJ/h
Gas CoolerT1=200 C, T2 = 150 CWater: T1=25 C, T2= 50 C, mass flowrate =2445 moles/hQ= mCpT Cp (UCG Gas) =2.14 J/gKCp (Slag) = 12 J/gKQ= -2555.198 kJ/h
Phase SeparatorEfficiency =0.85Q= mCpTT2= 90 CT1= 150 CQ= -37350.631kJ/hSteam generated = 261834 moles/h
Cyclone SeparatorEfficiency = 80 %Temperature = 90 C Q = mCp T =[ (Mass of slag*Cp)+(Mass of Water* Cp) ]* T = 149.035kJ/h
Acid Removal Assume Absorber as isothermalStripping Column:Lean MDEA = 110 CFeed = 90 CAcid Gas out = 95 CReboiler = 105 CCondenser = 93 CCondenser duty = mCp T= -11.401kJ/hReboiler duty = mCp T = 339.793 kJ/h
Gas CompressorAdiabaticPressure : 1 bar to 1.6Work = V * (P1-P2)Avg. Density = (mole fraction)*(density of component)= 7.43 kg/ m3Volume =m/Density = 35.5605 m3Work= -2133.628 kJ/hr
Challenges in UCG TechnologySuitable site:Geological and hydrogeology of seamsExcessive ingress of water into seam and leakage of gas into underground water suppliesGroundwater contaminationHeating of upper layers of soil and propery changesGround subsidence
ConclusionUnderground Coal Gasification Technology has been proven to work in numerous locationsMass balances carried out with a site in India as basis:Kalol(Gujarat)Total Heat Requirement = Compressor+Reboiler Duty+Cyclone Seperator = 2622.456 kJ/hrSyngas produced can be used for power generation as well as a chemical feedstock
Underground coal gasification:A new clean coal utilization technique for India ::Anil Khadse, Mohammed Qayyumi, Sanjay Mahajani, Preeti AghalayamUnderground Coal Gasification (UCG) Basic Files by Indiana Center for Coal Technology ResearchUnderground Coal Gasification Best Practices in Underground CoalGasification Elizabeth Burton :University of California, Lawrence Livermore National Laboratory Underground Coal Gasification : By CMRI DhanbadUnderground coal gasification: From fundamentals to applications Abdul Waheed Bhutto a, Aqeel Ahmed Bazmi b,c, Gholamreza Zahedi b,*The Research of UCG in lab conditions:Karol KOSTR, Monika BLIANOV :Faculty of Mining, Ecology, Process Control and Geotechnology Technical University of Koice Koice, Slovak RepublicResources and economic analyses of underground coal gasification in India Anil Nivrutti Khadse References