Performance and economics of a Pd-based planar WGS membrane reactor for coal gasification
✍ Scribed by M.D. Dolan; R. Donelson; N.C. Dave
- Publisher
- Elsevier Science
- Year
- 2010
- Tongue
- English
- Weight
- 610 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0360-3199
No coin nor oath required. For personal study only.
✦ Synopsis
Conceptual 300 tonne per day (tpd) H 2 -from-coal plants have been the subject of several major costing exercises in the past decade. Incorporating conventional high-and lowtemperature water-gas-shift (WGS) reactors, amine-based CO 2 removal and PSA-based H 2 purification systems, these studies provide a benchmark against which alternative H 2from-coal technologies can be compared. The catalytic membrane reactor (CMR), combining a WGS catalyst and hydrogen-selective metal membrane, can potentially replace the multiple shift and separation stages of a plant based on conventional technology. CMR-based shift and separation offers several major advantages over the conventional approach, including greater-than-equilibrium WGS conversion, the containment of the CO 2 at high-pressure and a reduction in the number of unit processes.
To determine capital costs of a WGS CMR-based H 2 -from-coal plant, a prototype planar CMR was constructed and tested with varying catalyst bed depth, residence time and membrane type (commercially-sourced 50 mm Pd or 40 mm Pd-25Ag wt%). Experiments to measure CO conversion, and H 2 flux and yield were conducted at 400 C with a feed pressure of 20 bar H 2 O:C ratio of 3 and a H 2 product pressure of 1 bar.
Under the optimum conditions examined (with a 40 mm-thick Pd-25Ag membrane and <3 mm-thick catalyst bed), a membrane surface area of w25,000 m 2 would be required to provide a throughput of 300 tpd with 85% H 2 yield. The capital cost of the CMR component of the plant would be around $US 180 million (based on current metal prices), of which 73% can be attributed to the cost of the PdeAg alloy membranes. Incorporation of a membrane that meets the 2015 US DOE cost and flux targets would offer cost parity, with a plant cost of $US 44 million and a total membrane area of w13,000 m 2 . Meeting these performance and cost targets would likely require a shift to very thin Pd-alloy membranes or highlypermeable Group IV, V body-centred-cubic alloys.