HYDROCARBON FUEL PROCESSING FOR FUEL CELL POWER PLANTS

摘要

The relative advantages of ATR's, Steam reformers and POX units are compared. The thermodynamic limits imposed on hydrocarbon processes are presented. The approach developed is to examine the fuel processing reactions using a DeDonder progress variable and then calculate the hydrogen production efficiency and gas composition as required by steam reforming equilibrium. The advantage of steam reforming is that the gas composition is richest in hydrogen. Steam reformers require twice the steam of an ATR. Systems studies show that this excess steam does not result in a large heat loss. If the equilibrium temperature in the steam reformer can be maintained near 1300℉ then a steam reformer should be considered for stationary fuel cell power plants. While a POX could, theoretically, have an O2/C ratio of 0.5, actual systems usually run at ratios near 0.65. This yields very low hydrogen production efficiency. The study results are shown in Figure 1. The catalyst bed temperature profile is of primary concern. The highest temperature must be at the exit of the ATR. If the temperature is permitted to drop after reforming has commenced, the ATR efficiency will be impaired. An exit temperature of not less than 1400℉ and oxygen to carbon ratio of less than 0.4 is required.