A Novel Membrane Reactor for Direct Hydrogen Production From Coal
Gas Technology Institute has developed a novel concept of a membrane reactor closely coupled with a coal gasifier for direct extraction of hydrogen from coal-derived syngas. The objective of this project is to determine the technical and economic feasibility of this concept by screening, testing and identifying potential candidate membranes under the coal gasification conditions. The best performing membranes were selected for preliminary reactor design and cost estimate. The overall economics of hydrogen production from this new process was assessed and compared with conventional hydrogen production technologies from coal. Several proton-conducting perovskite membranes based on the formulations of BCN (BaCe{sub 0.8}Nd{sub 0.2}O{sub 3-x}), BCY (BaCe{sub 0.8}Y{sub 0.2}O{sub 3-x}), SCE (Eu-doped SrCeO{sub 3}) and SCTm (SrCe{sub 0.95}Tm{sub 0.05}O{sub 3}) were successfully tested in a new permeation unit at temperatures between 800 and 1040 C and pressures from 1 to 12 bars. The experimental data confirm that the hydrogen flux increases with increasing hydrogen partial pressure at the feed side. The highest hydrogen flux measured was 1.0 cc/min/cm{sup 2} (STP) for the SCTm membrane at 3 bars and 1040 C. The chemical stability of the perovskite membranes with respect to CO{sub 2} and H{sub 2}S can be improved by doping with Zr, as demonstrated from the TGA (Thermal Gravimetric Analysis) tests in this project. A conceptual design, using the measured hydrogen flux data and a modeling approach, for a 1000 tons-per-day (TPD) coal gasifier shows that a membrane module can be configured within a fluidized bed gasifier without a substantial increase of the gasifier dimensions. Flowsheet simulations show that the coal to hydrogen process employing the proposed membrane reactor concept can increase the hydrogen production efficiency by more than 50% compared to the conventional process. Preliminary economic analysis also shows a 30% cost reduction for the proposed membrane reactor process, assuming membrane materials meeting DOE's flux and cost target. Although this study shows that a membrane module can be configured within a fluidized bed gasifier, placing the membrane module outside the gasifier in a closely coupled way in terms of temperature and pressure can still offer the same performance advantage. This could also avoid the complicated fluid dynamics and heat transfer issues when the membrane module is installed inside the gasifier. Future work should be focused on improving the permeability and stability for the proton-conducting membranes, testing the membranes with real syngas from a gasifier and scaling up the membrane size.
- Research Organization:
- Gas Technology Institute
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC26-03NT41851
- OSTI ID:
- 876470
- Country of Publication:
- United States
- Language:
- English
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A Novel Membrane Reactor for Direct Hydrogen Production from Coal
A NOVEL MEMBRANE REACTOR FOR DIRECT HYDROGEN PRODUCTION FROM COAL