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Show tubes are instrumented with thermocouples mounted to the external tube walls. Additional thermocouples were used to monitor cooling water temperatures, allowing calculation of heat removal rates on an individual tube basis. Phase I tests were performed on a ceramic fiber burner with a nominal fired duty of 400 MBtu/hr. A comparison is made between the PPH facility geometry and test conditions and typical reformer operating conditions in Table 4. As seen in the table, a fairly close correlation exists between maximum Phase I test conditions and required reformer conditions. The measured peak burner surface temperature was lower than predicted by the furnace modeling by over 100°F, which is an indication that burner surface emittance at reformer conditions is higher than was assumed in the original radiant burner modeling. This higher emittance should result in better overall heater performance than was predicted in the reformer modeling using an assumed emittance of 0.3. TABLE 4. COMPARISON OF PHASE I TEST CONDITIONS TO REFORMER REQUIREMENTS Parameter Condition Requirement(1) Burner Firing Rate2 (MBtu/hr-ft2) 100 112 Peak Burner Temperature (OF) 2368 2490 (based on € = 0.3) Maximum Sink Temperature (OF) 1698 1640 Radiant Efficiency (%)3 48.8 53.1 NOx (ppm at 3% O2) 19.5 9 - 25 Volumetric Heat Release Rate (MBtu/hr-ft3) 10.3 11.8 Process Tube OD (inch) 4 5 Tube Spacing (diameters) 1.5 1.5 1 Based on conceptual design by KTI 2Based on HHV 3Based on LHV The lower than anticipated burner surface temperature and relatively high radiant section thermal efficiency, considering the non-optimum design of the PPH firebox, indicate that the ARCS NOx target can be attained. Our current target is 25 ppm (corrected to 3 percent O2), but will be dependent on fuel composition, burner surface firing rate, and possibly combustion air preheat. NOx emissions from Pyrocore burners increase with surface firing rate and decrease with increased excess air. At a test condition of 100 MBtu/hr-ft2 and 20 percent excess air, emissions in the PPH furnace were 19.5 ppm. Our current baseline design has two burner segments operating at 112 MBtu/hr-ft2, and an average surface firing rate for 5 burner segments of less than 95 MBtu/hr-ft2. 14 |
