Abstract
Underground coal gasification was examined to be a new system for hydrogen production. For this purpose, a packed bed of coal in a quartz glass tube was used to simulate experimentally an underground coal gasification system. Carbonization of coal and char gasification reactions were investigated for discussion of the process of hydrogen production with H2O as a gasifier.
Results are summarized as follows.(1) Combustion reaction rate of the packed bed of coal was obtained from the propagation speed of flame front. Apparent activation energy for combustion reaction of coal in oxygen was 33 kJ/mol, which implies that mass transfer process may affect the combustion reaction. This means that the reaction rate and combustion temperature can be controlled by the flow rate of oxygen.(2) Production of hydrogen increased with combustion temperature and partial pressure of steam in the range of experiment. In the present study, 60 percent increment of hydrogen was attained in comparison with experiment of 02 as a gasifier.(3) Reaction, CO+H2O H2+CO2 was the most important for the increase of hydrogen production in a case of 600°C of combustion temperature, and both reactions, C+H2O H2+CO and CO +H2O-H2+CO2 contributed to the hydrogen production in the case of combustion temperatures higher than 750°C.
