Kerosinreformierung für Luftfahrtanwendungen

This thesis deals with fuel gas production from kerosene for fuel cells . Among other possibilities, fuel cells can contribute significantly to the reduction of emissions of an aircraft in flight or on the ground. A special approach was developed to deal with the broad content of the topic in an acceptable depth. The main focus was placed on the reforming process since the reformer can be considered as the heart of the system . However, the operation of the complete fuel processing system plays a key role for the success of the system. Therefore a well-balanced emphasis was also given to the fuel processing system . In order to carry out detailed analyses on the above-mentioned levels, namely the reformer level and the system level, two tools were selected : experiment and simulation. The reforming process was examined by means of extensive experiments, whereas studies on the complete system were supported by simulations. Firstly, the specifications of the fuel kerosene Jet A-1 were analysed to obtain a better understanding of the physical and chemical characteristics of this substance. Later, a reaction scheme was developed to describe the characteristics of the reforming process . Models for the necessary components of the various fuel processing systems were developed and verified experimentally . Using statistic simulations the reactor components were optimised and combined to build up fuel processing systems with a high level of heat integration . Realistic process conditions like the startup of the system and the load change characteristics were simulated using dynamic simulations . Additionally, the characteristics of the different reformers, the transient behaviour and the long-term performance were tested. The simulations show that the fuel processing system for a Solid Oxide Fuel Cell (SOFC) offers the highest advantages among the three systems analysed because of its simplicity. The system for a Polymer Electrolyte Fuel Cell (PEFC) is complicated since many components are required for the fuel gas clean-up . Its operation under transient conditions is difficult requiring an advanced control system . The system for a High Temperature Polymer Electrolyte Fuel Cell (HT-PEFC) has advantages over the PEFC system under transient operation conditions. Additionally, the system is simpler since fewer components are required. The experiments with desulphurised kerosene Jet A-1 showed that an excellent quality product gas can be produced for 500 h with the ATR 7 reformer . With the ATR 8 reactor a conversion level of 99 % was still achieved after 2000 hours of operation. Start-up experiments showed that the start-up time is mainly limited by the external steam preparation mechanism . Load change experiments showed that the ATR 5B reformer exhibits excellent behaviour under tough load change conditions .