Abstract
IHI has been developing PEFC system to utilize various fuels including natural gas and liquid petroleum fuel. These systems include fuel cell, fuel processor, inverter, automatic control system, pumps, blower and so on in one unit. The commercialization of PEFC system is expected as minimum scale (5kw to 20kW) co-generation system, which will be suitable for small electricity users including restaurants, stores, and gas stations. In order to enhance the thermal efficiency for these systems, reduction of auxiliary power consumption such as blower, improvement of cell voltage and an advanced thermal efficiency of fuel processor are necessary. Fuel cell is designed to achieve low-pressure drop in order to reduce the auxiliary power. Pressure drop at the cathode of a 5kW class stack (LPD-stack) is less than 4.9kPa and fuel utilization ratio could be more than 80% using simulated reformate. Fuel processor is designed to be compact and to achieve high thermal efficiency. Reformer, shift-converter and selective oxidizer are included in one adiabatic vessel with a burner. We have developed a burner for this processor that burns fuel gas and hydrogen gas at the same time. The start-up takes about 30 minutes at daily start-and-stop mode and 45 minutes at weekly start-and-stop. NOx concentration in the exhaust is nearly zero. We have developed the commercial prototype 5kW for small electricity users. IHI goes on to enhance power generation efficiency and makes the unit more compact.
