1. Field of the Invention
The present invention relates to a reformer fuel cell system. The present invention further relates to a method for starting and/or operating a reformer fuel cell system.
2. Description of the Prior Art
Reformer fuel cell systems have been known for a long time. A reformer consisting of a plurality of partial reformer systems generates from a primary fuel a hydrogen-rich gas which is used for the generation of electric current in a fuel cell. Known partial reformer systems are, for example, reformer devices, vaporizers, heat exchangers, shift stages, and gas fine-cleaning stages.
Small reformers for fuel cells with a low electric power have, for example, been disclosed in DE-A-100 40 539, DE-A-100 32 059 or DE-A-101 18 618.
Adequate heat supply is required for the startup and continuous operation of both the reformer and the fuel cell. Particularly if reformer fuel cell systems with low power are operated in the part load mode, there is the danger that the heat available is insufficient. As a result, the reformer process on the one hand and the fuel cell process on the other hand may deteriorate or even come to a standstill.
As has been disclosed in DE-A-199 10 387, an additional heating system the operating heat of which is used to heat a fuel cell stack is provided for heating up a fuel cell unit on cold start. The heating system heats a heat transport medium which is supplied through the reaction chamber of the fuel cell stack, thereby heating up the latter.
DE-A-199 31 061 has disclosed an arrangement for heating and cooling a fuel cell system in which a reformer can be integrated in addition to a burner and a cooler. A heating or cooling medium circulating in a closed circuit within the system serves to regulate the internal heat flux, especially to heat the gaseous medium flows supplied to the fuel cell.
DE 103 15 225 A1 describes a reformer fuel cell system in which, for heating purposes, the exhaust gas from an external burner or a heat transfer medium heated by an external burner can be supplied to the reformer or the fuel cell.