Coal
Melt
Regeneration
and recycle
NaCO 3
recycle
Air or
oxygen
Low-Btu gas (w/N 2 )
Med-Btu gas (w/O 2 )
Ash and
sulfur
(a)
Pretreated coal
O 2
Steam
Raw gas
Water
Dust removal
Waste heat boiler
Gas cleaning
(b)
Slag
FiGUre 4.3 Schematics of two typical molten salt gasifiers: (a) Rockwell molten salt gasifier;
(b) Rummel–Otto single-shaft gasifier. (Adapted from Lee, S., Speight, J.G., and Loyalka,  S.K.,
Handbook of Alternative Fuel Technologies. Taylor & Francis, Boca Raton,   FL, 2007;
Lee,  S., “Gasification of coal,” in Lee, S., Speight, J.G., and Loyalka, S.K., eds., Handbook of
Alternative Fuel Technologies. Taylor & Francis, Boca Raton, FL, 26–78, 2007.)
85
Steam Gasification and Reforming Technologies
1. Salt bath supplies the necessary heat for gasification. Due to high and uniform
temperature in the bath, products are free of impurities such as tars and tar acids.
2. Gasification of caking coal without carbonization is possible due to uniform
distribution of coal and steam and good contacting between the two reactants.
3. Complete gasification at a lower temperature is possible due to catalytic effect
of sodium carbonate for coal steam gasification reactions.