Effective utilization of coal has attracted attention as one of the possible solutions to recent energy issues.
To convert coal to a highly value-added energy medium, advanced technologies, such as a coal gasification technology and a gas purification technology, are required.
An Integrated Coal Gasification Combined Cycle that generates electricity using gasified gas has been proposed (Patent Literature 1).
The Integrated Coal Gasification Combined Cycle (IGCC) is a system that converts coal into combustible gas in a high-temperature and high-pressure gasifier and generates electricity through a combined cycle with a gas turbine and a steam turbine by using the gasified gas as fuel.
An example of the above is illustrated in FIG. 2. FIG. 2 is an explanatory diagram of a coal gasification power plant according to a conventional technology. As illustrated in FIG. 2, a coal gasification power plant 100 gasifies coal 101 in a gasifier 102 to obtain gasified gas 103 as synthesis gas, removes dust from the gas in a dust removal apparatus 104, such as a scrubber, converts COS into H2S in a COS converter 105, causes a CO shift reaction to occur in a CO shift reactor 106, and recovers CO2 and removes H2S in an H2S/CO2 recovery apparatus 107.
Synthesis gas 108 obtained through treatment by the H2S/CO2 recovery apparatus 107 is supplied to a combustor 111 in a gas turbine 110 being a power generating means, where the synthesis gas is fired and high-temperature and high-pressure combustion gas is produced. A turbine 112 is driven by the combustion gas. The turbine 112 is connected to a power generator 113 so that the power generator 113 generates electricity when the turbine 112 is driven. Flue gas 114 produced by the driving of the turbine 112 has, a temperature of 500 to 600° C. Therefore, it is preferable to feed the flue gas to an HRSG (Heat Recovery Steam Generator (an exhaust heat recovery boiler)) 115 in order to recover heat energy. In the HRSG 115, steam is produced by the heat energy of the flue gas. A steam turbine 116 is driven by the steam. The flue gas whose heat energy is recovered by the HRSG 115 is fed to a denitrification apparatus (not illustrated) to remove NOx from the flue gas and thereafter released into the air through a stack 117. In FIG. 2, a reference numeral 120 denotes air, 121 denotes an air separator, 122 denotes a gasification air compressor, 123 denotes gasification air, 124 denotes steam, and 125 denotes an H2S/CO2 treatment system.
As described above, for the gasified gas 103 obtained through the gasification in the gasifier 102, the CO shift reactor 106 that converts CO contained in the gasified gas into CO2 is needed before the CO2 is separated.
The CO shift reaction is performed to obtain CO2 and H2 as useful components as expressed by the following Expression (1).CO+H2O→CO2+H2  (1)
Various CO shift catalysts have been proposed as catalysts for promoting the CO shift reaction. Examples of the catalysts include an aluminum oxide supported molybdenum (Mo)-cobalt (Co) based catalyst (Patent Literature 2).
The CO shift reactor 106 converts a large amount of CO contained in the gasified gas 103 into H2. Therefore, the obtained gas is also used for the synthesis of chemical products, such as ethanol or ammonia, in addition to be used for turbines.