A microchannel sulphur tolerant steam reformer with integral multi-zone catalytic combustor

The aim of this Ph.D. is to develop and evaluate a compact 'fast response' hydrocarbon fuel processor with integrated control software and novel design concepts for use with both stationary and transportation applications using PEM fuel cells. A multi-function compact chemical reactor designed for hydrocarbon steam reforming was evaluated. The reactor design is based on diffusion bonded laminate micro-channel heat exchanger technology. The reactor consists of a combustor layer, which is sandwiched between two steam reforming layers. Between the two function layers, a temperature monitoring and control layer is placed, which is designed to locate the temperature sensors. The combustor layer has four individually controlled combustion zones each connected to a separate fuel supply. The reactor design offers the potential to accurately control the temperature distribution along the length of the reactor using closed loop temperature control. The experimental results show that the variance of temperature along the reactor is negligible. The conversion efficiency of the combustor layer is approximately 90 to 100%. The heat transfer efficiency from combustion layer to reforming layers is 65% to 85% at 600°C and 400°C, respectively. A sulphur tolerant catalyst, designed for use w1th LPG, was washcoated on to the reforming layers. The reformer was tested over a wide range of reactor temperatures, steam to carbon ratios and fuel flow rates. To increase the reformer performance a second nickel-based catalyst was added to the rear of the reformer. The multi-zoned combustor enabled the two catalysts to be operated at differing temperatures as required. The reformer was tested over a further range of operatmg temperatures, steam to carbon ratios and feed rates whilst using the fuels, LPG, C3Hs and CH4 The performance of the reformer whilst using C3Hs and LPG showed good agreement suggesting that the perfonnance of the reformer was not adversely affected by the presence of sulphur in the fuel. 98% conversion of C3H8 was achieved at a predicted fuel cell power output of 1.98kWe.