This Presentation describes the process of Underground Coal Gasification and production of Clean Synthesis Gas which can be further processed to make SNG or Synthetic Diesel
3. UCG PRINCIPLES & ESSENTIALS
• Underground Coal Gasification (UCG) converts coal
into a gaseous form (syngas) through the same
chemical reactions that occur in surface gasifiers
• The economics of UCG look promising as capital
expenses should be considerably less than surface
gasification Essentials
• Site location -biggest issue
• Coal characteristics–operations
• Technologies
4. • Flexibility in commercial use
• Superior environmental profile
• Lower cost
• No SOx, NOx
• Converts unminable coal
• Encourages low rank coal
(sub-bituminous/lignite)
• No coal washing
5. How does UCG work?
• Step1: Find the coal
• Step2: Drill the boreholes
• Step3: Link the boreholes
• Step4: Ignite the coal
• Step5: Inject O2 and steam
• Step6: Extract the syngas
8. 2/ Combustion Zone Oxidation zone exothermic Temperature rising Coal consumed
C+O2 CO2 C+1/2 O2 CO 2CO+O2 2 CO2 CH4+O2 CO2+2H2O
3/ Gasification Zone Reduction zone Endothermic Temperature falling until
reactions stop no more coal consumed
C+CO2 2 CO H2O+C CO+H2
4/ Reduction Zone Gas transport zone Lower temperature
Shift conversion reaction reduces heat value of gas
CO+H2O CO2+H2
methanation C+2 H2 CH4
General Gasification Zones in Burn Cavity
along burn direction
Initiation of cavity using counter current flow1/ De-volatilization zone
4
3
2
1
Adapted from
9. Recent Developments in UCG
Controlled Retractable Ignition Point (CRIP)
Source: Ind. Eng. Chem. Res., Vol. 48, No. 17, 2009
