A complete details about Underground coal gasification process and latest techniques and methods..

2. Contents:
• What is UCG?
• Introduction
• Suitable conditions for UCG
• Technology for UCG
• Principle of UCG
• Linkage techniques
• UCG methods
• Advantages and disadvantages

3. What is UCG:
 UCG is an advanced & innovative method in mining among
Underground/surface.
 It is an industrial process which convert coal into syn gas (product
gas).
 UCG means the in-situ gasification of coal.
COAL+WATER+O2+HEAT=HYDROGEN+CO+(other minor gases)

4. Introduction:
Year of invention: 1868
Invented by : Sir William Siemens
Developers: African carbon energy & Ergo
energy technology.
Why UCG:
• Increasing price of oil and natural gas.
• Growing demand for alternative energy
source.
Uses:
• For power generation , fuel , fertilizers &
explosives etc(…)

6. Suitable conditions for UCG:
• Should not have high geological disturbances
• Roof & floor should have low permeability it helps
preventing leakage and coal have high permeability .
• Free from water, if any then drained out.
• Coal should be low quality, sub-bituminous and lignite are
preferred due to its low permeability.
• Seam thickness is 6m is preferable.
• Reserves should be high.
• Site should be close to consumers.
-Thin & Thick : 0.75m & 20m
-Shallow & Deep : 40m & 300m
-Low And High VM : 3.7% & 64.5%
-Flat And Vertical Seams.

7. Condition should be checked out:
1. Physical & chemical properties.
2. Litho logical properties .
3. Hydrological properties.
4. Geological disturbances.
5. Coal bed structure.
6. seam thickness.
7. Forming laying.
8. Environment impact.

9. Process of UCG:

10. Technology of UCG:
• In former days this process is done by the sinking shaft or
drift from surface , but it is not going on present days.
• Now a days two holes will be drilled with an interval of 30-
80m apart and are connected by a channel made in coal
seam by making use of natural permeability of deposit.
• Water or air will be injected through the holes with high
pressure , is called linking operation.
• After drilling 2 bore holes , the coal is ignited and
combustion is maintained by injecting air or oxygen &
stream through one bore hole.
• The resulting high pressurized gases are contained with
the seam by overlying impermeable rocks and water
pressure in the surrounding coal and overburden.
• The hydraulic gradient is maintained in the cavities.
• Drilling pattern is depends on the gradient of seams

12. Principle of UCG:
1. Under ground gas generator.
2. Surface plant to receive gas and process it for use in the
power stations.
The process of sending of air or oxygen through a burning
coal seam to produce combustible gas which is brought to
surface.
Which involves :
• Oxidation zone (or) combustion zone.
• Reduction zone.
• Dry distillation (or) pyrolysis.
The reactions :
Exothermic Reactions: Endothermic Reactions:
1) C + O2 CO2 + heat 1)CO2 + heat + C 2CO
2) 2H2 + O2 2H2O+heat 2)H2O + heat + C CO + H2

14. Linkage techniques:
1. Compressed air linkage:
high pressure air > ground pressure.
rate of linkage depends on permeability of coal bed
i.e. 3-4 days.
linkage is restored if he permeability of coal is less.
2. Electro linkage:
electrodes will be placed 25m apart coal acts as
conductor.
when coal heated 200-250’c changes take place in
electrical resistance, fissures developed.
due to voltage drop , current increases air blast take
place at a pressure of 0-8atmp and linka.ge is
restored.

15. 3. Bore hole linkage:
A bore will be drilled vertically with 152mmm
dia. And Direction goes inclinely with 90’ till
reaching the coal seam .
another vertical holes drilled with an interval of
75m.
4. Percolation linkage:
linkage will be established by the percolation of
gasses in vertical hole.
middle hole will be drilled and ignited by
passing of air, during the course of time cracks
will be developed and linkage will be established.

17. Methods of UCG:
1. Chamber Method (Or) Shaft Method:
suited for existed u/g mine.
brick wall is constructed b/w 2 pannels .
 Favours for low permeability of coal and
explosives are used.
2. Bore Hole Method:
suitable for flat laying seams.
2 parallel underground galleries will be opened.
process of linkage will be electrical &hydraulic.

19. 3. Stream Method:
used for sharp inclined seams
2 parallel galleries will be connected with
horizontal gallery .
4. CRIP (Controlled Retractable Injection Point) method:
Combination of conventional and directional
drilling to access coal seam.
it provides burner to retractable coiled tubing
to initiate ignition, it can be moved to desired
location.

20. Advantages:
• NO risk , NO accidents i.e. elimination of hard jobs
(human safe).
• No heaps, dumps & less impact on environment.
• Most convenient transport of fuel.
• Re-agriculture can be done after uninstalling UCG.
• Shorter and flexible system of transportation.
• Eco friendly and environmentally less impact.
• Less labor and in dangerous gas source.
• Less public allegations.

21. Disadvantages:
• Sail will be getting damaged by headgear, pipes.
• Capital is more( large headgear , pipes)
• Water table getting damage.
• Extraction of reserves is less than the deep mining.
• Energy balance is also less favorable than the deep
mine.
• The gas is dirty and less calorific value.
• Damage to environment-drill rig, head gear piping, top
soil damage by machinery.
• Noise of drilling
• Large are is require so restricted by some countries.

22. Thank You