Advanced IGCC-Hypogen Concepts for a Developing Hydrogen Market

Within FP6 the EU is funding a project called ¿Dynamis¿ which aims to design plants to generate electricity, plus a limited amount of hydrogen from fossil fuels, in which the CO2 is captured and stored underground in suitable geological reservoirs. Such plants have been characterised as being of the ¿HYPOGEN¿ type since they generate both hydrogen and electric power. Steam reforming could be used when the fuel is natural gas. With coal the plant would be based on entrained flow IGCC and can be referred to as IGCC-Hypogen schemes. But as the hydrogen market develops IGCC-Hypogen based systems will need to produce much greater amounts of hydrogen. It is also desirable that such plants should be able to vary the proportion of hydrogen-to-electricity. This will enable IGCC-Hypogen plants to load follow and two-shift as electricity demand from the grid changes. Such variations in power output are not always practical with existing designs of electricity-only IGCCs. In particular, efficiency drops because of the high power demand of the plant ancillaries, which includes the Air Separation Unit (ASU), Acid Gas Removal (AGR) and CO2 compression units and with some types of gasifier there can be problems with start up. Designed-in flexibility will enable an IGCC-Hypogen plant to increase its hydrogen output as the market develops. This paper reviews the technical issues involved in providing a high-flexibility IGCC-Hypogen plant. Three such concepts are discussed (i) very limited flexibility in which the changes from a fixed hydrogen-electricity ratio concept are minor, (ii) moderate level of flexibility in which the limit is imposed by the CCGT gas turbine turndown (iii) complete flexibility, the plant being able produce the energy as all-electricity or all-hydrogen.

STARR Frederick;  CORMOS Calin-Cristian;  TZIMAS Evangelos;  BROWN Andrew; 

2009-02-10

I ChemE

JRC37977