(35a) Development of ATR Fuel Processor for Reformation of Logistic Fuels

Fuel cell power systems are an attractive solution for future portable power generation in many applications such as battlefield, shipboard, remote construction sites, etc. In developing viable fuel cell-based power generation units, durability of reforming systems to continuously supply hydrogen and to permit stable, coke-free fuel cell stack operation via catalytic reforming of commonly available fuels is a key challenge. Precision Combustion, Inc. (PCI) has developed an Auto Thermal Reformer (ATR) unit and has demonstrated stable, coke-free operation using a low-sulfur, Tier II diesel for ~1100 hours with complete fuel conversion and reforming efficiency of >80% (ratio of LHV of reformate to fuel). In this unit, a distillate fuel (e.g., JP-8 or diesel) was processed with low water usage; therefore, the test demonstrated the feasibility of long-term operation at a low steam-to-carbon ratio while producing SOFC-quality reformate (i.e., <10 ppmv of higher hydrocarbons).

In this paper, we will give an overview of the ATR development at PCI and will show some performance results when operating the reactor using a low-sulfur fuel. Additionally, we will present experimental results obtained from ATR sulfur tests using JP-8 fuels consisting of various sulfur levels. Here, the fuels were doped with an organic sulfur surrogate or contained naturally occurring sulfur compounds. The effect of increasing fuel-sulfur level on the ATR performance, including fuel conversion, reforming efficiency, H2 selectivity, and reformate composition will be discussed. In our study, the sulfur level in the liquid fuel was increased stepwise from 4 ppmw to 3000 ppmw by doping a low-sulfur fuel with dibenzothiophene. At each sulfur level, the ATR reactor was operated for at least 50 hours and the ATR reformate stream was analyzed for H2, CO, CO2, higher hydrocarbons as well as H2S and carbonyl sulfide. This study helped to clarify issues surrounding reformation of sulfur containing fuels and to illustrate one possible approach for reformation of higher sulfur logistic fuels for fuel cell applications.

Finally, long-term durability data on the ATR reforming of JP-8 with 400 ppmw naturally occurring sulfur will also be presented. The data will be compared with the results obtained from operating the ATR reactor using doped sulfur fuels. The evaluation of the reactor performance results from this set of 50-hour tests using different sulfur fuels provides a measure of the ATR performance that can be expected under realistic conditions with readily available fuels. The results also give valuable insights to the system design and operation strategy of the integrated fuel reformer and APU system.