Vol 1 Chapter 15: Development of a Hydrogen Mixed Conducting Membrane Based CO2 Capture Process
Bent Vigeland and Knut Ingvar Aasen
Abstract: The aim of this CCP sub-project has been to develop dense hydrogen mixed conducting ceramic membranes (HMCM) with sufficient H2 transport rates and stability under normal methane steam reforming conditions, and further develop a techno economically viable precombustion de-carbonization (PCDC) power generating process applying said materials. In the novel natural gas to hydrogen process a two step membrane reformer system replaces the traditionally hydrogen production train. The membrane reformer concept combines steam methane reforming and HMCM. Hydrogen generated in the steam methane reformer sections is transported through the membrane and is in a first step reacted with air extracted from a gas turbine to generate a nitrogen and steam containing sweep gas. This sweep gas is used to recover most of the hydrogen in a membrane reformer step two generating a high pressure (15– 20 bar) hydrogen fuel containing about 40% H2, 40% N2 and 20% H2O. The hydrogen fuel mixture is then combusted with air in the gas turbine. The low hydrogen concentration in the fuel is a major advantage since this will depress formation of nitric oxides in the combustion chamber to 15 ppmv or below. The residual synthesis gas containing mainly CO2, H2O and CO is further converted to CO2 and H2O in a residual gas oxidation section. CO2 can then be captured simply by condensation of the water vapor. A large number of candidate membrane materials have been synthesized and characterized followed by hydrogen permeability measurements in atmospheric laboratory tests at both SINTEF and University of Oslo (UiO). Based on the measurements and theoretical evaluations, a main candidate materials system, was selected. Theoretical analyses indicate that the membranes will be stable above 700 8C under process conditions. Supported membrane tubes have been fabricated and tested by Hydro in a pressurized hydrogen flux test rig under relevant process conditions. The measured H2 flux in the test rig compares favorably with model predictions. Based on cost estimate from Fluor the CCP CEM team did a cost analysis to evaluate the potential for this technology compared with, e.g. theNorwegian baseline technology. This indicates that the hydrogenmembrane reformer process has the potential to reduce the cost of CO2 capture in a CCGT power plant with at least 50%.
Carbon Dioxide Capture for Storage in Deep Geologic Formations – Results from the CO2 Capture Project Capture and Separation of Carbon Dioxide from Combustion Sources - Volume 1
Edited by: David C. Thomas, Senior Technical Advisor, Advanced Resources International Inc, USA
(472 Kb) Download