Partial catalytic dehydrogenation of selected components of kerosene

Kurzfassung

Conventional gas turbine auxiliary power units (APUs) supply an airplane with power during on-land operations, though have a poor efficiency and high emissions. To lower emissions and fuel consumption, these APUs could be replaced by fuel cells that produce "clean and silent" energy. The approach of partial catalytic dehydrogenation (PCD) is chosen to supply the fuel cell with hydrogen, extracted from kerosene. The PCD system consists of a fractioning to remove sulphur (operating at 1 bar) the actual dehydrogena-tion and a gas purification to remove gaseous hydrocarbons (operating at 8 bar). Surrogates of kerosene are created to investigate the influence of single substance groups on the dehydrogenation. In a test bench, extensive dehydrogenation tests are performed with single components of the surrogates, namely n-decane and methylcyclohexane (MCH). Ideal operating conditions for 1 bar —the pressure of the upstream process— and 8 bar —the pressure of the downstream process— are determined in respect of achieving a high hydrogen yield and a low coke formation, the latter important for a stable process. Furthermore, the composition of the gaseous and liquid product is investigated. For 1 bar, a temperature of 400 oC and a contact time of 2sec are found which result in a stable process with a hydrogen yield of 460 nLH2 kg^-1 MCH. For 8 bar, the optimal temperature and contact time are 425 °C and 4 sec, resulting in higher coke formation and a hydrogen yield smaller than 100 nLH2 kg^-1 MCH. The determination of which pressure level results in the better overall efficiency of the PCD system is beyond the boundaries of this work but must be evaluated in a subsequent process simulation.