The operation of solid oxide fuel cells on various fuels, such as natural gas, biogas and gases derived from biomass or coal gasification and distillate fuel reforming has been an active area of SOFC research in recent years. In this study, we develop a theoretical understanding and thermodynamic simulation capability for investigation of an integrated SOFC reformer system operating on various fuels. The theoretical understanding and simulation results suggest that significant thermal management challenges may result from the use of different types of fuels in the same integrated fuel cell reformer system. Syngas derived from coal is simulated according to specifications from high-temperature entrained bed coal gasifiers. Diesel syngas is approximated from data obtained in a previous NFCRC study of JP-8 and diesel operation of the integrated 25 kW SOFC reformer system. The syngas streams consist of mixtures of hydrogen, carbon monoxide, carbon dioxide, methane and nitrogen. Although the SOFC can tolerate a wide variety in fuel composition, the current analyses suggest that performance of integrated SOFC reformer systems may require significant operating condition changes and/or system design changes in order to operate well on this variety of fuels.

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A low-swirl burner (LSB) developed for laboratory research has been scaled to the thermal input levels of a small industrial burner. The purpose was to demonstrate its viability for commercial and industrial furnaces and boilers. The original 5.28 cm i.d. LSB using an air-jet swirler was scaled to 10.26 cm i.d. and investigated up to a firing rate of Q ‫ס‬ 586 kW. The experiments were performed in water heater and furnace simulators. Subsequently, two LSBs (5.28 and 7.68 cm i.d.) configured to accept a novel vaneswirler design were evaluated up to Q ‫ס‬ 73 kW and 280 kW, respectively. The larger vane-LSB was studied in a boiler simulator. The results show that a constant velocity criterion is valid for scaling the burner diameter to accept higher thermal inputs. However, the swirl number needed for stable operation should be scaled independently using a constant residence time criterion. NO x emissions from all the LSBs were found to be independent of thermal input and were only a function of the equivalence ratio. However, emissions of CO and unburned hydrocarbons were strongly coupled to the combustion chamber size and can be extremely high at low thermal inputs. The emissions from a large vane-LSB were very encouraging. Between 210 and 280 kW and 0.8 Ͻ Ͻ 0.9, NO x emissions of Ͻ15 ppm and CO emissions of Ͻ10 ppm were achieved. These results indicate that the LSB is a simple, low-cost, and promising environmental energy technology that can be further developed to meet future air-quality rules.

The physical, thermal, and chemical behavior of pulverized coal particles during thermal decomposition are examined for five coal types and two particle sizes for one of the bituminous coals. Particles were injected axially into a lean (35% excess air) methane/air fiat flame with a nominal peak temperature of 1750~ The significant events observed are classified by three time scales. Particles heat to the gas temperature in less than 10 msec, devolatilization occurs between 10 and 75 msec and, under the appropriate conditions, large soot particles are formed WRS and grow for times exceeding 75 msec.The events that accompany devolatilization are dependent upon coal type and particle size. For large bituminous particles (ca., 80 Izm) a significant volatile fraction is ejected from the particle as a jet. This volatile jet reacts close to the particle producing a trail of small solid particles. The local heat released during the reaction of the volatiles, in combination with heterogeneous oxidation, increases the particle temperature and raises it above that of the bulk gas stream. At later times, large soot structures are formed which are attributed to the agglomeration of small, homogeneously formed soot on the volatile trail structures.Small bituminous particles (ca., 40 Ixm) burn with a higher intensity (i.e., higher temperature and more rapidly) with few trails and do not produce soot structures probably because of the more diffuse nature of the devolatilization process.Other ranks of coal exhibit different physical, thermal, and chemical behavior. For example, neither the lignites nor the anthracite produce volatile trails. Further, the particle temperature for the lignites is only slightly shifted above the bulk gas temperature in the devolatilization region while anthracite takes 50 msec to reach the bulk gas temperature level. This is attributable to the relatively low heat content of the volatiles in the former case and the low volatile content in the latter.The impact of the above observations on the formation of fuel NO is discussed.