Project No: FE0007271
Performer: University of Pittsburgh


Contacts

Richard A. Dennis
Technology Manager, Turbines
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880
Morgantown, WV 26507-0880
304-285-4515
richard.dennis@netl.doe.gov

Steven Richardson
Project Manager
National Energy Technology Laboratory
3610 Collins Ferry Road
P.O. Box 880
Morgantown, WV 26507-0880
304-285-4185
steven.richardson@netl.doe.gov

Brian Gleeson
Principal Investigator
University of Pittsburgh
636 Benedum Hall
Pittsburgh, PA 15213-2303
412-648-1185
bgleeson@pitt.edu

Duration
Award Date:  10/01/2011
Project Date:  09/30/2014

Cost
DOE Share: $434,324.00
Performer Share: $128,378.00
Total Award Value: $562,702.00

Performer website: University of Pittsburgh - http://www.pitt.edu

Advanced Energy Systems - Hydrogen Turbines

Degradation of TBC Systems in Environments Relevant to Advanced Gas Turbines for IGCC Systems

Project Description

This project will determine the degradation mechanisms of current state-of-the-art thermal barrier coating (TBC) in environments comprised of particulate matter and gas mixtures which are representative of gas turbines using coal-derived synthesis gas (syngas). The observed degradation processes will be used to guide the development of improved coatings for hot section components in the potentially harsh gas turbine environments in which fuels derived from coal and even perhaps biomass are burned. The unresolved complexities associated with TBC durability include enhanced attack of yttria-stabilized zirconia (YSZ) top coating by chemical reaction, physical damage of the topcoat by molten deposit penetration, and accelerated bond coat corrosion. This work is investigating how the interaction between the ash and oxidants affect TBC degradation by using lab-scale testing. Important outcomes from this study will include understanding TBC degradation; modeling integrated gasification combined cycle (IGCC) environments to develop better coatings; and extending the service life of TBCs by mitigating degradation.

This research is using the high-temperature corrosion testing facilities at the University of Pittsburgh. The deposits currently being used are based on fly ash, and accordingly, consist of calcium oxide (CaO), aluminum oxide (Al2O3), silicon dioxide (SiO2) and iron oxides (FeOx). Additions of potassium sulfate (K2SO4) and iron sulfide (FeS) are used to simulate other ash constituents. The tests are being conducted on two different TBC system types provided by Praxair Surface Technologies (PST) of Indianapolis, Indiana. PST will also conduct thermal gradient tests for assessing TBC durability with and without deposits. Both exposed and unexposed test samples are being extensively characterized using the suite of capabilities available at the University of Pittsburgh.

Free-standing YSZ coupons reacted with commercial fly ash. A thin reaction layer formed at 1200 °C, while the ash melted and severely degraded the YSZ at 1300 °C.

Free-standing YSZ coupons reacted with commercial fly ash. A thin reaction layer formed at 1200 °C, while the ash melted and severely degraded the YSZ at 1300 °C.


Program Background and Project Benefits

Turbines convert heat energy to mechanical energy by expanding a hot, compressed working fluid through a series of airfoils. Combustion turbines compress air, mix and combust it with a fuel (natural gas, coal-derived synthesis gas [syngas], or hydrogen), and then expand the combustion gases through the airfoils. Expansion turbines expand a working fluid like steam or supercritical carbon dioxide (CO2) that has been heated in a heat exchanger by an external heat source. These two types of turbines are used in conjunction to form a combined cycle— with heat from the combustion gases used as the heat source for the working fluid— improving efficiency and reducing emissions. If oxygen is used for combustion in place of air, then the combustion gases consist mostly of carbon dioxide (CO2) and water, and the CO2 can be easily separated and sent to storage or used for Enhanced Oil Recovery (EOR). Alternatively, the CO2/steam combustion gases can be expanded directly in an oxy-fuel turbine. Turbines are the backbone of power generation in the US, and the diverse power cycles containing turbines provide a variety of electricity generation options for fossil derived fuels. The efficiency of combustion turbines has steadily increased as advanced technologies have provided manufacturers with the ability to produce highly advanced turbines that operate at very high temperatures. The Advanced Turbines program is developing technologies in four key areas that will accelerate turbine performance, efficiency, and cost effectiveness beyond current state-of-the-art and provide tangible benefits to the public in the form of lower cost of electricity (COE), reduced emissions of criteria pollutants, and carbon capture options. The Key Technology areas for the Advanced Hydrogen Turbines Program are: (1) Hydrogen Turbines, (2) Supercritical CO2 Power Cycles, (3) Oxy-Fueled Turbines, and (4) Advanced Steam Turbines.

Hydrogen turbine technology research is being conducted with the goal of producing reliable, affordable, and environmentally friendly electric power in response to the Nation's increasing energy challenges. NETL is leading the research, development, and demonstration of technologies to achieve power production from high hydrogen content (HHC) fuels derived from coal that is clean, efficient, and cost-effective; minimize carbon dioxide (CO2) emissions; and help maintain the Nation's leadership in the export of gas turbine equipment. These goals are being met by developing the most advanced technology in the areas of materials, cooling, heat transfer, manufacturing, aerodynamics, and machine design. Success in these areas will allow machines to be designed that have higher efficiencies and power output with lower emissions and lower cost.

The University of Pittsburgh will utilize high-temperature corrosion testing facilities to determine the degradation mechanisms of current state-of-the-art thermal barrier coating (TBC) in environments comprised of particulate matter and gas mixtures which are representative of gas turbines using coal-derived synthesis gas (syngas). The observed degradation processes will be used to guide the development of improved coatings for hot section components in the potentially harsh gas turbine environments in which fuels derived from coal and even perhaps biomass are burned. Materials research conducted under the Advanced Turbine Program seeks to improve coating materials that will allow for higher temperature operation and increased durability. These improvements will improve turbine efficiency and reduce maintenance, leading to lower capital costs, reduced operating costs, and reduced costs of electricity for consumers.

Accomplishments