5 kW SOFC power plant test station

A 5 kW class solid oxide fuel cell (SOFC) test system is presented. The purpose of the system is to demonstrate a small-scale SOFC combined heat and power plant that includes all main components needed in plant operation. Main research issues in the operation of the test system consist of component testing and characterization, research of the interactions between different components of the plant and development of automation and control strategies for SOFC systems. The system operates at atmospheric pressure using reformed natural gas as fuel. Alternatively, hydrogen can be used as fuel as well during characterization or system stand-by situations. The system is designed for a planar anode-supported stack that is delivered by Forschungszentrum Jülich. Natural gas is pre-reformed using an autothermal reformer (ATR) unit. Air is supplied to the cathode with a blower. Heat exchangers are used to heat up the stack inlet fuel and air flows. At the air side, a heat exchanger exists for low and high temperature. Unused fuel present in the anode exhaust gas is utilized using a catalytic afterburner. Hot exhaust gases from the afterburner are led through a water-cooled plate heat exchanger. Electric power is transformed using a grid interconnection device, which converts direct current produced by the stack to alternating current and phases it with the distribution grid. Automation and control of the system is achieved with a standard industrial programmable logic controller and a PC-based monitoring station. Automation and control system monitors various process parameters, e.g. voltages, temperatures and pressures. The SOFC test system is controlled according to the electric power demand. The control system maintains steady-state operating conditions by adjusting e.g. fuel and air flows, and the composition of the reformate gas. In addition to the steady-state controls, there exists a back-up system for emergency shutdown situations e.g. in the case of a power outage or fuel supply failure