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Research Papers: Gas Turbines: Cycle Innovations

# Analysis of Operational Strategies of a SOFC/Micro Gas Turbine Hybrid Power Plant

[+] Author and Article Information
Martina Hohloch

German Aerospace Center (DLR),
Institute of Combustion Technology,
Pfaffenwaldring 38-40,
Stuttgart 70569, Germany
e-mail: martina.hohloch@dlr.de

Andreas Huber, Manfred Aigner

German Aerospace Center (DLR),
Institute of Combustion Technology,
Pfaffenwaldring 38-40,
Stuttgart 70569, Germany

1Corresponding author.

Contributed by the Cycle Innovations Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received July 31, 2017; final manuscript received September 15, 2017; published online July 24, 2018. Editor: David Wisler.

J. Eng. Gas Turbines Power 140(8), 081703 (Jul 24, 2018) (9 pages) Paper No: GTP-17-1416; doi: 10.1115/1.4038605 History: Received July 31, 2017; Revised September 15, 2017

## Abstract

The present work deals with the analysis of operational concepts for a solid oxide fuel cell/micro gas turbine (SOFC/MGT) hybrid power plant based on a test rig at the DLR, Institute of Combustion Technology. Here, a Turbec T100 MGT and a fuel cell emulator are used. The emulator is composed of two pressure vessels. The first represents the cathode volume of the fuel cell to simulate the residence time and pressure loss. The second is equipped with a natural gas combustor to emulate the varying heat input of the fuel cell. The MGT and the SOFC are connected via different piping paths. The procedures start-up, load change, and shutdown are analyzed in matters of temperature gradients, pressure gradients, and fluctuations, as well as the air mass flow provided at the interconnections to the coupling elements. To achieve the required inlet conditions of the SOFC, transient operations, using the different piping paths, are investigated. Concepts for heating up and cooling the SOFC using hot air from the recuperator and relatively cold air from the compressor outlet are experimentally tested and characterized. Selected critical situations and their effect on the SOFC are investigated. An emergency operation and its impact on both subsystems and limitations are shown. Further operational limits of the MGT control system and power electronic were observed and analyzed. Based on the experimental results, the applicability of the used MGT procedures in a hybrid power plant was reconsidered. Finally, adaptions and strategies for the operational concept are derived and discussed.

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## References

Pierre, J. F. , 2008, “ High Temperature Solid Oxide Fuel Cell Generator Development,” National Energy Technology Laboratory, U.S. Department of Energy, Morgantown, WV, DOE Cooperative Agreement No. DE-FC26-97FT34139, Final Technical Progress Report.
Roberts, R. , and Brouwer, J. , 2006, “ Dynamic Simulation of a Pressurized 220 kW Solid Oxide Fuel-Cell-Gas-Turbine Hybrid System: Modeled Performance Compared to Measured Results,” ASME J. Fuel Cell Sci. Technol., 3(1), pp. 18–25.
Yi, Y. , Smith, T. P. , Brouwer, J. , Rao, A. D. , and Samuelsen, G. S. , 2003, “ Simulation of a 220 kW Hybrid SOFC Gas Turbine System and Data Comparison,” Electrochemical Society, Pennington, NJ, pp. 1442–1454.
Veyo, S. E. , 2003, “ Tubular SOFC Hybrid Power Systems,” Third DOE/UN International Conference and Workshop on Hybrid Power Systems, Newport Beach, CA, May 13.
Hohloch, M. , Widenhorn, A. , Lebküchner, D. , Panne, T. , and Aigner, M. , 2008, “ Micro Gas Turbine Test Rig for Hybrid Power Plant Application,” ASME Paper No. GT2008-50443.
Hohloch, M. , Zanger, J. , Widenhorn, A. , and Aigner, M. , 2010, “ Experimental Characterization of a Micro Gas Turbine Test Rig,” ASME Paper No. GT2010-22799.
Hohloch, M. , Huber, A. , and Aigner, M. , 2014, “Experimental Investigation of a SOFC/MGT Hybrid Power Plant Test Rig: Impact and Characterization of Coupling Elements,” ASME Paper No. GT2014-25918.
Hohloch, M. , Huber, A. , and Aigner, M. , 2016, “ Experimental Investigation of a SOFC/MGT Hybrid Power Plant Test Rig: Impact and Characterization of a Fuel Cell Emulator,” ASME Paper No. GT2016-57747.
Tucker, D. , Lawson, L. , and Gemmen, R. , 2005, “ Characterization of Air Flow Management and Control in a Fuel Cell Turbine Hybrid Power System Using Hardware Simulation,” ASME Paper No. PWR2005-50127.
Pascenti, M. , Ferrari, M. L. , Magistri, L. , and Massardo, A. F. , 2007, “ Micro Gas Turbine Based Test Rig for Hybrid System Emulation,” ASME Paper No. GT2007-27075.
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## Figures

Fig. 1

Scheme and instrumentation of the applied hybrid power plant test rig setup

Fig. 2

Selected tubular SOFC concept

Fig. 3

MGT start-up to 75% turbine speed

Fig. 7

SOFC inlet conditions: (a) air inlet temperature, (b) air inlet pressure, and (c) air mass flow

Fig. 8

Cooling of SOFC using different paths: (a) cooling of SOFC, path combination 1 and (b) cooling of SOFC, path combination 2

Fig. 9

MGT shutdown: (a) stop of MGT starting at 75% turbine speed and TOT = 600 °C and (b) stop of MGT starting at 75% turbine speed and TOT = 550 °C

Fig. 4

Heating-up of SOFC using different paths

Fig. 5

MGT hot start-up to 75% turbine speed

Fig. 6

MGT load changes: (a) load change from 80% to 83% turbine speed and (b) load change from 87.5% to 75% turbine speed

Fig. 10

Fig. 11

Surge event: (a) surge event plotted against time and (b) surge event in the compressor map

Fig. 12

Stepwise bleed-air opening and closing at 90% turbine speed

## Errata

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