Testing

The testing procedure was divided in three phases:

Phase I: Functional test of all components according to given specifications.(Cold Test).

- Supply rates-functionality-electrical/electronical-flow control. Phase II: System functional test without SOFC stacks. (Warm Test I).

-Thermal control -fuel management Phase III: System functional test including SOFC stacks.(Warm Test II).

- Start up-operation-close down- system control and monitoring.

Both test phase I and II were performed without major problems. However, the final system functional test suffered from mechanical problems related to inferior strength of the stack interconnect material. The final test was then postponed, in order to concentrate on the interconnect problem. As a result of this effort, the mechanical strength of the interconnect material has been raised by a factor of 1.7, thus resulting in mechanical properties well within the required specifications. The final system test will be restarted in late autumn this year.

The results from test phase I and II were very encouraging related to system performance. No fatal incidents occured, the control system performed well, and an emergency shut down during the first system functional test was properly handled without any damage to the plant. Nevertheless, small cracks in metallic weldings in the high temperature zone was found during the inspection of the plant after test It has been established that these cracks were a result of the combination of inadequate welding procedures and constructional imperfections. This problem is now solved by new design and more experience in welding of these high temperature alloys.

Prior to the test, the possibility of soot and carbon formation in heat exchangers and afterburner was a concern. However, no indications of such reactions were found in later pilot test investigations, probably due to excellent behaviour of the prereformer and a system geometry which provided for the right temperature balances throughout the whole system.

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