Geological Research at the IGS
Evaluation of Indiana Coals for Integrated Gasification Combined Cycle (IGCC)
||Jun 1, 2006
||May 31, 2008
Clay, Daviess, Gibson, Greene, Knox, Pike, Posey, Sullivan, Vanderburgh, Vermillion,
||The main deficiency in predicting the behavior of Indiana coals in an Integrated Gasification Combined Cycle (IGCC) is the lack of data on the properties that govern slag behavior in a gasifier. Properties of mineral matter, and specifically, ash chemical composition, ash melting point, slag viscosity are essential for understanding slag buildup and corrosion of the gasifier, both of which are critical issues for successful IGCC system operation.
||This is a 2-year study to evaluate Indiana coals in IGCC systems. The project includes field work, sample collection, new analytical work, as well as integration of new and existing
data for interpreting coal performance in an IGCC. We target major economic coal beds: the Danville, Hymera, Springfield, and Lower Block. Sampling locations are selected such that:
1) an adequate distribution of data points is provided using new and existing data, in order to
map the degree variability of individual parameters important for IGCC; and 2) available coal mines and drilling locations are used to obtain fresh samples.
||New analytical work include:
1. Mineral matter (ash) composition
At least 10 new locations in each of the selected coal beds will be sampled, and the samples will be analyzed for the chemical composition of the mineral matter. If possible, the chemistry of the slag will be assessed on some selected slag samples derived form these coals. Based on these chemical measurements, numerous parameters will be calculated for individual coal beds, with special emphasis on: base/acid ratio, silica/alumina ratio, silica ratio, and slagging index. These parameters will help predicting slag behavior during gasification.
2. Ash melting point and slag viscosity
We will obtain new analyses of ash fusion temperatures (AFT) and ash viscosities on the selected coal beds. The sampling locations will be the same as for ash composition; however, because very few data of this type are available on Indiana coals, in addition to whole-seam channel samples, bench samples (subsections of a coal bed) will be collected and analyzed. On average, 3 bench samples from each location will be collected, resulting in 40 samples for each coal bed (10 whole seam channel samples plus 30 bench samples). This number of samples will help documenting regional lateral variations of these parameters in each coal bed, and also help to understand factors that influence these parameters on a local scale.
3. Petrographic composition
In addition to mineral matter chemical characterization, all the coal samples collected will be characterized mineralogically using petrographic and x-ray diffraction techniques. This will include the determination of both the maceral composition of coal as well as all non-maceral minerals. Percentage of maceral type will be determined on the macerals. Vitrinite reflectance will be measured. Maceral composition influences coal reactivity, while vitrinite reflectance reflects changes in coal rank. Char reactivity increases from inertinite (lowest reactivity) through vitrinite to liptinite (highest reactivity).
4. Chlorine content in coal
Chlorine data in 10 new locations for each coal bed will be obtained. Attempts will be made to obtain additional chlorine data from mining companies. Additional chlorine data will significantly enhance our understanding of variability and distribution of chlorine content within Indianas coals. Low chlorine content (<0.4%) is required for IGCC plant, and the content lower than 0.2% are preferred. As with other constituents, consistency of clorine content is a critical factor.
||The new research will provide:
1) Comprehensive document on the evaluation of Indiana coals for IGCC application. The report will include:
a. Tables of coal properties important to IGCC use and summaries of individual parameters for Indiana coal beds;
b. Maps of parameter distributions;
c. Discussions of the ranges of the values of individual parameters in relation to selection of
Indiana coals for different gasifier types; and
d. Final evaluation of Indiana coals for IGCC, including recommendations about the
modeling of their behavior in gasifiers.
2) An updated coal properties database that which will include the new data obtained during the project, as well as data already included in the existing database. This database would provide, in addition to currently existing parameters, information related to slag behavior.
||The report and the database will be available to funding agencies and collaborators, as well as coal companies, utilities, policy makers, personnel of the existing and future IGCC plants, and any other interested parties. The results will be also presented at national and international conferences.