ISBN 9783843939256

978-3-8439-3925-6, Reihe Verfahrenstechnik

Jonas M. Leimert
Hydrogen Generation from solid Feedstock based on the Heatpipe Reformer Technology

301 Seiten, Dissertation Universität Erlangen-Nürnberg (2018), Softcover, A5

Zusammenfassung / Abstract

The Heatpipe Reformer provides an allothermal gasification process for the generation of a hydrogen-rich synthesis gas. Liquid metal heat pipes transport the heat required for fuel gasification from a fluidized bed furnace to the steam-blown fluidized bed gasification reactor. This allows the generation of synthesis gas with a hydrogen content of up to 50 % and a very low nitrogen content. In contrast to other dual fluidized bed processes the completely sealed reformer chamber makes a pressurized process of possible resulting in a high hydrogen partial pressure and thus driving force for separation. This work therefore follows the approach to apply hydrogen permeable membranes as separation step directly in the reformer. This also allows higher hydrogen yields due to an additional shift of the gasification reactions to the product side as one product is continuously removed.

Existing approaches to high temperature hydrogen separation like palladium composite membranes or ceramic materials show advantages and disadvantages mainly regarding stability and prices. The presented approach applies commercial nickel capillary tubes as membranes.

The experimental section presents measurements with a nickel membrane bundle, which was used for a demonstration of the shift of different gas mixtures by hydrogen removal to the product side. The hydrogen removal could significantly enhance CO and CH4 conversion in the bottle-mixed synthesis gas at an operation temperature of 800°C. The membranes produced hydrogen with a very high purity of at least 99.9 % due to the highly selective solution-diffusion process of the separation.

The measurements with the 100 kW Heatpipe Reformer including results on tar and sulfur content of the generated synthesis gas are also introduced. The Heatpipe Reformer was operated both on lignite and wood pellets, which allows a comparison of these feedstock with respect to their suitability for hydrogen production. An energy balance provides both the analysis of the gasification reaction in terms of energy usage and the prediction of the efficiency for a commercial Heatpipe Reformer system, which lies above 70 % in terms of cold gas efficiency. All gathered data were used to provide an energetic analysis of a 1 MW process for Hydrogen generation using the Heatpipe Reformer technology with membrane separation.