Gasification and oxy-combustion

FIGURE 9.22 Layout for a gasification-based system for co-production of hydrogen and electrical power while sequestering C02 [51]. Reprinted with permission from Elsevier. 

Air-blown gasifiers benefit from a low-cost (free) source of oxidant, but produce a gasifier product gas that has a very low heating value (approximately 5MJ/m3 for air-blown gasification of coal, compared to 38MJ/m3 for a typical natural gas) and which is too dilute to use for liquid fuel synthesis. 

Oxygen-blown gasifiers yield a moderate heating value product gas (approximately 9MJ/m3) and can operate at very high temperatures, but suffer from the significant cost of producing oxygen with an air-separation unit. 

FIGURE 9.23 Adiabatic flame temperature for stoichiometric combustion of methane in mixtures of oxygen with nitrogen and oxygen with carbon dioxide, computed using NASA s Chemical Equilibrium Analysis (CEA) program [52]. 

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