Goro ISHIDUKA

An Investigation on the Availability of Exhaust Gas from a Micro Gas Turbine for Solid Oxide Fuel Cells

Kazunori SATO

The operating temperature of conventional solid oxide fuel cells (SOFCs) is above 800 degrees Celsius. SOFC can use various hydrocarbons reformed into hydrogen-rich fuels and shows high efficiency in electric power generation. Micro gas turbines (¦ÌGTs) are the advanced electric generation systems due to their elevated gas temperatures. However, scaling down of the ¦ÌGT system influences the flow and combustion process leading to a low efficiency of the electric power generation. The exhaust heat and gas from a ¦ÌGT is therefore suitable for SOFC. In the present study the exhaust gas composition, oxygen concentration, and the temperature distribution were measured mainly for a ¦ÌGT burner with a quadrupole mass spectrometer analyzer, a solid electrolyte oxygen sensor, and thermocouples.
The results showed that a lean combustion, whose equivalent ration was 0.21, occurred in the temperature range between 600-1000 degrees Celsius. The maximum temperature of the exhaust gas was observed at the position apart from the exit the burner. An increase in the maximum temperature resulted in an increase in the temperature gradient to the exit position of exhaust gas. It was found that the excess of oxygen supply leads to residual fuels in the exhaust gas. This is probably caused by an partial extinction of the flame in the burner due to an insufficient combustion near the inner wall of the burner, where the flame collide, and/or limited time for a flow of combustion gas. Low operating temperature, approximately 600-800 degrees Celsius, and the exhaust gas composition seem to be promising for the combined electric power generation system

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