A NOVEL MEMBRANE REACTOR FOR DIRECT HYDROGEN PRODUCTION FROM COAL
Gas Technology Institute is developing a novel concept of membrane reactor coupled with a gasifier for high efficiency, clean and low cost production of hydrogen from coal. The concept incorporates a hydrogen-selective membrane within a gasification reactor for direct extraction of hydrogen from coal-derived synthesis gases. 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 high temperature, high pressure, and harsh environments of the coal gasification conditions. The best performing membranes will be selected for preliminary reactor design and cost estimates. To evaluate the performances of the candidate membranes under the gasification conditions, a high temperature/high pressure hydrogen permeation unit has been constructed in this project. The unit is designed to operate at temperatures up to 1100 C and pressures to 60 atm for evaluation of ceramic membranes such as mixed protonic-electronic conducting membrane. Several 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}), Eu-doped SrCeO{sub 3} (SCE) and SrCe{sub 0.95}Tm{sub 0.05}O{sub 3} (SCTm) were successfully tested in the new permeation unit. During this reporting period, a thin BCN membrane supported on a porous BCN layer was fabricated. The objective was to increase the hydrogen flux with a further reduction of the thickness of the active membrane layer. The thinnest dense layer that could be achieved in our laboratory currently was about 0.2 mm. Nevertheless, the membrane was tested in the permeation unit and showed reasonable flux compared to the previous BCN samples of the same thickness. A long term durability test was conducted for a SCTm membrane with pure hydrogen in the feed side and nitrogen in the sweep side. The pressure was 1 bar and the temperature was around 1010 C. No decline of hydrogen flux was observed after continuous running of over 250 hours. This long term test indicates that the perovskite membrane has good thermal stability under the reducing conditions of the hydrogen atmosphere. A conceptual design of the membrane reactor configuration for a 1000 tons-per-day (TPD) coal gasifier was completed. The design considered a tubular membrane module located within the freeboard area of a fluidized bed gasifier. The membrane ambipolar conductivity was based on the value calculated from the measured permeation data. A membrane thickness of 25 micron was assumed in the calculation. The GTI's gasification model combined with a membrane reactor model were used to determine the dimensions of the membrane module. It appears that a membrane module can be configured within a fluidized bed gasifier without substantial increase of the gasifier dimensions.
- Research Organization:
- Gas Technology Institute (US)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- FC26-03NT41851
- OSTI ID:
- 840470
- Resource Relation:
- Other Information: PBD: 28 Apr 2005
- 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