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Research Papers: Gas Turbines: Cycle Innovations

# Open Loop and Closed Loop Performance of Solid Oxide Fuel Cell Turbine Hybrid Systems During Fuel Composition Changes

[+] Author and Article Information
Nor Farida Harun

National Energy Technology Laboratory,
U.S. Department of Energy,
Morgantown, WV 26507-0880
e-mails: Nor.Harun@NETL.DOE.GOV;
norf.harun@gmail.com

David Tucker

National Energy Technology Laboratory,
U.S. Department of Energy,
Morgantown, WV 26507-0880
e-mail: David.Tucker@NETL.DOE.GOV

Department of Chemical Engineering,
McMaster University,
1280 Main Street West,

1Corresponding author.

Contributed by the Cycle Innovations Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received November 30, 2016; final manuscript received December 13, 2016; published online February 1, 2017. Editor: David Wisler.This work is in part a work of the U.S. Government. ASME disclaims all interest in the U.S. Government's contributions.

J. Eng. Gas Turbines Power 139(6), 061702 (Feb 01, 2017) (9 pages) Paper No: GTP-16-1555; doi: 10.1115/1.4035646 History: Received November 30, 2016; Revised December 13, 2016

## Abstract

The dynamic behavior of a solid oxide fuel cell gas turbine hybrid system (SOFC/GT) from both open and closed loop transients in response to sudden changes in fuel composition was experimentally investigated. A pilot-scale (200–700 kW) hybrid facility available at the U.S. Department of Energy, National Energy Technology Laboratory was used to perform the experiments using a combination of numerical models and actual equipment. In the open loop configuration, the turbine speed was driven by the thermal effluent fed into the gas turbine system, where the thermal effluent was determined by the feedforward fuel cell control system. However, in the closed loop configuration, a load-based speed control system was used to maintain the turbine speed constant at 40,500 rpm by adjusting the load on the turbine, in addition to the implementation of the fuel cell system control. The open loop transient response showed that the impacts of fuel composition changes on key process variables, such as fuel cell thermal effluent, turbine speed, and cathode feed stream conditions, in the SOFC/GT systems were propagated over the course of the test, except for the cathode inlet temperature. The trajectories of the aforementioned variables are discussed in this paper to better understand the resulting mitigation/propagation behaviors. This will help lead to the development of novel control strategies to mitigate the negative impacts experienced during fuel composition transients of SOFC/GT systems.

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## References

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## Figures

Fig. 1

The recuperated SOFC/GT hybrid test facility at NETL [10]

Fig. 2

Hardware-based simulations of SOFC/GT hybrid system

Fig. 5

A comparison profiles of fuel cell thermal effluent for open loop and closed loop tests

Fig. 3

Load based speed control scheme [10]

Fig. 4

Turbine speed and turbine load responses for open and closed loop configurations

Fig. 6

A comparison of turbine inlet and exhaust temperatures for open loop configuration versus closed loop configuration: (a) the real profiles and (b) the normalized profiles

Fig. 7

A comparison of cathode inlet mass flow for open loop configuration versus closed loop configuration

Fig. 8

Normalized profiles of (a) system mass flow, compressor discharge pressure, and turbine speed for open loop configuration and (b) system mass flow, compressor discharge pressure, and turbine load for closed loop configuration

Fig. 10

Normalized profiles of (a) system pressures and turbine speed for open loop configuration and (b) system pressures and turbine load for closed loop configuration

Fig. 9

A comparison of cathode inlet pressure for open loop configuration versus closed loop configuration

Fig. 11

A comparison of cathode inlet temperature for open loop configuration versus closed loop configuration

## Errata

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