Project Philosophy

stacks, as well as makes the entire construction easily adapted to later scaleup of electrical performance.

engineering and construction

The engineering activity was started when the feasibility and conceptual studies were completed. A detailed thermodynamic system analysis set the guidelines for the later design of heat exchangers, afterburner, electrical heaters and fuel cell chamber.This analysis concluded that the system would be self supplied, electrical heaters would be necessary only for the startup and close down of the pilot plant. By utilization of plate heat exchangers, a very compact design was found to be technical feasable. Mathematical modelling and simulations showed that a partial prereforming of the natural gas was beneficial, and thus a prereformer unit was designed as a part of the low temperature heat excanger combined with a backup external prereformer.

The engineering work was performed according to experience, know how, rules and regulations given by Statoil and Norwegian authorities. Finite element analysis tools were used for detailed fluid, thermal and thermodynamic analysis of the details and the integrated system. The fuel cell stack operating temperature of 1000 degrees centigrade results in maksimum temperatures approaching 1100 degrees centigrade in the afterburner. This called for extensive studies of material properties and behaviour. The materials for the BOP were selected based on a series of dedicated tests of several alloys in both reducing and oxidizing environments.

Special attention was paid to the problem of thermoelastic deformations. Flexible joint elements were designed, tested and implemented in order to avoid destructive thermomechanical forces that would break metallic welds and destroy ceramic components. A specially designed suspension system for the beat exchangers had to be developed for the same reasons.

Sealing methods were developed, tested and implemented for metal/metal, metal/ceramic and ceramic/ceramic connections.

In order to minimize loss of produced electrical power in the stack system, a dedicated current collector system for SOFC stacks were developed and patented. The system performance is based on a combination of specially designed current collectors and pneumatic stack pressurizing elements, resulting in significant improved electrical performance with very low degradation rate.

Considering the SOFC pilot plant to be operating in a specific Statoil industrial environment, the possible risk and hazards involved in such an operation were carefully investigated throughout the engineering and construction phase. Risk analysis concluded that the SOFC pilot plant was more safe than conventional industrial petrochemical plants. Hazop studies as well confirmed the plant to be free from fatal design errors and set the standard for reliable operational prosedures. In this respect the pilot plant was given the required authorisation both by Norwegian authorities and Statoil.

The instrumentation of the plant, being the very first of its kind in Norway, was by intention made considerable more comprehensive than needed for the purpose of surveillance and process control. This was done due to the need of scientific and diagnostic data. The control'and monitoring of the plant were decided to be partly manual and partly automated. The supply system is physically separated from the fuel cell compartment, while control and monitoring equipment of the plant are installed in a separate control room. This system layout was mainly determined by safety as well as operational and maintenance reasons. The control functions are handled by local controllers, operated from the control room.

The process monitoring and data aquisition are performed by dedicated computers, which will handle alarms and give warning signals to the operator. In stationary operations the plant will run unmanned at nights and manned in daytime.

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