Abstract Booklet 2006 - Swanson School of Engineering - University ...

Heat-exchangers, particle filters, turbines, and other components in integrated coal
gasification combined cycle system must withstand the highly sulfiding conditions of the
high-temperature coal gas over an extended period of time. The performance of components
degrades significantly with time unless expensive high alloy materials are used. Deposition
of a suitable coating on a low-cost alloy may improve its resistance to such sulfidation
attack, and decrease capital and operating costs. The alloys used in the gasifier service
include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive
nickel-cobalt alloys such as Inconel, Hastelloy and Haynes alloys. Not only are these
materials expensive, their machining is also difficult, which makes fabrication of
components particularly costly.
SG Solution's coal gasification power plant in Terre Haute, IN, uses ConocoPhillips' E-Gas
technology. The need for corrosion-resistant coatings exists in two areas: (1) the tube sheet
of a heat exchanger at ~1000°C that is immediately downstream of the gasifier, and (2)
porous metal particulate filter at 370°C, which is downstream of the heat exchanger. These
components operate at gas streams containing as much as 2% H 2 S. This corrosion is the
leading cause of the unscheduled downtime at the plant and hence success in this project will
directly impact the plant availability and its operating costs. Coatings that are successfully
developed for this application will find use in similar situation in other coal-fired power
plants. A protective metal or ceramic coating that can resist sulfidation corrosion will extend
the life-time of these components and reduce maintenance.
SRI has developed a low-cost fluidized-bed-reactor chemical vapor deposition (FBR-CVD)
technology to deposit coatings of various metals including Cr, Si, Ti, Al, B, Ni, W, and Mo
on metals and ceramics. SRI s method for depositing corrosion-resistant coatings also has
advantages over the commonly used techniques such as thermal or plasma spraying, which
produce coatings with internal porosity and microcracks, so that they must be thick to
prevent gas penetration to the substrate. The FBR-CVD technology allows (1) both internal
and external surfaces to be coated, (2) diffusion bonding to the substrate, and (3) formation
of a dense layer on the surface and increased corrosion protection of the substrate.
We have successfully deposited coatings of Cr, Cr-Al, Ti, Ti-Al nitrides, and Si-Al nitrides
on various steel samples, and tested them in simulated gasifier environments. Coatings on
low carbon steels in the 400 series was most effective as these samples showed minimal
corrosion under conditions where Inconel and other coated samples were badly corroded.
Ferritic steels appear to be more suitable for diffusion barrier coatings than steels containing
Ni. Some of the coated samples have been placed in the SG Solutions gasifier plant in Terre
Haute, IN, and we await their retrieval at the next scheduled maintenance.
39-2
Oxidation of Alloys for Advanced Steam Turbines
Gordon Holcomb, Malgorzata Ziomek-Moroz, David E. Alman, NETL, USA
Ultra supercritical (USC) power plants offer the promise of higher efficiencies and
lower emissions. Current goals of the U.S. Department of Energy s Advanced Power
Systems Initiatives include power generation from coal at 60% efficiency, which
requires steam temperatures of up to 760°C. This research examines the steam
oxidation of alloys for use in USC systems, with emphasis placed on applications in
high- and intermediate-pressure turbines.
39-3
Experimental Evaluation for Fireside Corrosion Resistance of Advanced
Materials for Ultra-Supercritical Coal-Fired Power Plants
Horst Hack, Greg Stanko, Foster Wheeler North America Corp, USA
The U.S. Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) are
co-sponsoring a project, managed by Energy Industries of Ohio (EIO), to evaluate candidate
materials for coal-fired boilers operating under ultra-supercritical (USC) steam conditions.
Power plants incorporating USC technology will deliver higher cycle efficiency, and lower
emissions of carbon dioxide (CO 2 ) and other pollutants than current coal-fired plants.
Turbine throttle steam conditions for USC boilers approach 732°C (1350°F), at 35 MPa
(5000 psi). The materials used in current boilers typically operate at temperatures below
600°C (1112°F) and do not have the high-temperature strength and corrosion properties
required for USC operation. Materials that can meet the high temperature strength and
corrosion requirements for the waterwalls and superheater/reheater sections of USC boilers
need to be tested and evaluated.
The focus of the current work is experimental evaluation of fireside corrosion resistance of
candidate materials for use in USC boilers. These materials include high-strength ferritic
steels (SAVE12, P92, HCM12A), austenitic stainless steels (Super304H, 347HFG, HR3C),
and high-nickel alloys (Haynes® 230, CCA617, INCONEL® 740, HR6W). Protective
coatings (weld overlays, diffusion coatings, laser claddings) that may be required to mitigate
corrosion were also evaluated. Corrosion resistance was evaluated under synthesized coalash
and flue gas conditions typical of three North American coals, representing Eastern
(mid-sulfur bituminous), Mid-western (high-sulfur bituminous), and Western (low-sulfur
sub-bituminous) coal types. Laboratory testing for waterwall materials was performed at
455°C (850°F), 525°C (975°F), and 595°C (1100°F). The superheat/reheat materials were
exposed to 650°C (1200°F), 705°C (1300°F), 760°C (1400°F), 815°C (1500°F), and 870°C
(1600°F). Samples were exposed for 1000 hours, with ash being replenished every 100
hours to maintain aggressive conditions. Samples were evaluated for thickness loss and
subsurface penetration of the corrosive species. The laboratory testing was useful for
screening different alloys in controlled environments, where the different variables of alloy
content, temperature, fuel/ash and sulfur in the flue gas could be evaluated.
35
Promising materials from the laboratory tests were assembled on corrosion probes for testing
in three utility boilers. Air-cooled, retractable corrosion probes were designed to maintain
metal temperatures using multiple zones, representing USC superheat/reheat temperatures,
ranging from 650°C (1200°F) to 870°C (1600°F). The probes were installed in utility
boilers, equipped with low NO x burners, representing each of the three coal types. This paper
presents an update on the current status of this ongoing fireside corrosion advanced materials
research program.
39-4
Carbon Molecular Sieve Membrane/Module and its Use for
Hydrogen Production for Coal
Paul Liu, Richard Ciora, Media & Process Technology, Inc., USA
Theodore Tsotsis, University of Southern California, USA
Carbon, due to its inertness, is considered an ideal material candidate for handling
coal-related process streams. Although carbon molecular sieve (CMS) materials have
been used extensively in industry as adsorbents, they have not moved beyond the
academic novelty stage as a membrane material. Two major application-related
barriers have prevented industrial acceptance of a CMS membrane, specifically, (i)
poisoning and/or aging by a wide range of contaminants/impurities present in the
atmosphere either during storage or in the stream to be treated and (ii) the lack of a
module that is both cost and commercially/industrially acceptable, particularly for a
high temperature and high pressure applications. Media and Process Technology Inc.
has overcome these two barriers by choosing appropriate operating conditions and
developing a CMS/ceramic composite membrane/module. One of the major
application focuses for this CMS membrane/module is hydrogen/electricity coproduction
from coal. By operating at an intermediate temperatures, i.e., 150 to 300°C,
our unique CMS membrane/module can function as a simple hydrogen separator or as
a membrane reactor for water gas shift reaction. Hydrogen permeances of 1 to
>3 m 3 /m 2 /hr/bar and H 2 /CO selectivities of 50 to >100 are typical in this operating
temperature range. Based upon the performance of the membrane and the features of
the module, we have developed several process scenarios for hydrogen production
from coal. Process intensification as a result of the use of our membrane/module will
be presented.
39-5
FT-IR and XRD Study of Tirap Coal
Binoy K. Saikia, R. K. Boruah, P K Gogoi, Tezpur University, INDIA
Coal sample from Tirap colliery of Assam, India was studied using FTIR and XRD
methods. FTIR study shows the presence of aliphatic -CH, -CH 2 and -CH 3 groups,
aliphatic C-O-C stretching associated with -OH and -NH stretching vibrations and
HCC rocking (single and condensed rings). XRD pattern of the coal shows that it is
amorphous in nature. Function of Radial Distribution Analysis (FRDA) indicates that
coal is lignite in type and there is no evidence of graphite like structure. The first
maximum in the FRDA at R = 0.133 nm relates to the C = C bond (Type C – CH = CH
– C), the second maximum at R = 0.25 nm relates to the distance between carbon
atoms of aliphatic chains that are located across one carbon atom. The curve intensity
profiles obtained from FRDA show quite regular molecular packets for this coal.
SESSION 40
ENVIRONMENTAL CONTROL TECHNOLOGIES: MERCURY – 2
40-1
Recent Advances in Trace Metal Capture Using Micro and Nano-Scale Sorbents
Jason D. Monnell, Radisav D. Vidic, University of Pittsburgh, USA
Dianchen Gang, West Virginia University Institute of Technology, USA
Andrew Karash, Evan J. Granite, DOE/NETL, USA
The adsorption of mercury, arsenic, and selenium on micro and nano-scale sorbents is
reviewed. In particular, efforts on trace metal capture from coal-derived gas streams
using nano-scale sorbents are summarized. A collaborative effort between the
University of Pittsburgh, WVU Tech, and NETL on the development of novel micro
and nano-scale sorbents has been initiated with the preliminary results presented
herein. Future research directions are suggested and an extensive list of references is
provided.
40-2
Aqueous Mercury and Lead Removal with Activated Carbons
Derived from High Sulfur Carbonaceous Materials
Shitang Tong, Shuqing Zhang, Xiaoqing Wu, Wuhan University of Science and
Technology, CHINA
Jenny Cai, Loraine Laiyin Chiu, Donald W. Kirk, Charles Q. Jia, University of
Toronto, CANADA
Hg and Pb are of environmental concerns due to their toxic and bioaccumulative
nature. Developing cost effective adsorbents for controlling their emissions to the