The paper reviews the merits of the main types of coal and lignite based gasifiers and examines in detail how the need to co-produce electricity and high purity hydrogen efficiently and to capture carbon dioxide using off-the shelf Integrated Gasification Combined Cycle (IGCC) based processes, affect the choice of gasifier and the ancillary plant equipment.
The significant issues in the overall design of hydrogen and electricity co-production systems with carbon capture are: (i) the required oxygen purity to minimise Pressure Swing Adsorption (PSA) equipment size and reduce tail gas loss, (ii) downstream gas clean up issues and implications for gasifier choice, and (iii) the potential loss of H2 and CH4 during removal of hydrogen sulphide (H2S) and capture of carbon dioxide (CO2) from the gas stream.
The paper also comments on the longer term desirability of producing hydrogen at high pressure, indicating some future development needs in terms of plant design.
The results of this paper stem from the work at the Joint Research Centre (JRC) in the context of the Dynamis IP project under the Sixth Framework Programme. Dynamis project aims at developing technologies for hydrogen and electricity co-production based on fossil fuels with 90 % carbon capture rate.