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