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Show 2.0 2.2 A Case Study The procedure described above will now be illustrated by means of a practical case study. The particular case in point is a design that is being carried out by KTI and Shell for a major Los Angeles basin refinery. The following are the most pertinent data for the design: • flue gas flow rate: 61,130 Ib/hr • flue gas temperature: 3300 F • NOx conversion required: 87 percent • NH3 slip permitted: 5 ppm • allowable pressure drop: 3 inches of water column • S02 concentration: at the start of the study this was somewhat uncertain. Under normal operating conditions of the refinery fuel gas desulfurization units, S02 in the flue gas should be less than 5 ppm. However, it was anticipated that occasional fluctuations could result in higher values. Shell was asked to advise on which S02 level would still be compatible with the 3300 F denoxing temperature. Tests at our research lab revealed that 10 ppm S02 was the threshold level corresponding to an operating temperature of 3300 F. The required 87% NOx conversion was attained at a space velocity of 5,000 (in units of normal m3 of flue gas processed per hour per m3 of catalyst material). The required amount of catalyst for the specified flue gas flow rate works out as about 4.5 m3. The total reactor volume is roughly twice as large: 11.0 m3. The pressure drop restrictions can be satisfied with an LFR having the following rough dimensions: • catalyst slabs of 1.6 inch thickness • reactor size in the direction perpendicular to the gas flow: 9.5 ft by 9.5 ft; and 5.3 ft along the flow direction. 3.0 CONCLUDING REMARKS We have presented some details about Shell's new denox technology. This technology can be used in low temperature (T < 5000 F) as well as in "conventional" temperature (5000 to 7000 F) applications. The low-T option offers significant advantages, especially in retrofit projects, making costly and time consuming work on existing furnaces unnecessary. In the conventional temperature applications, Shell denox technology is competitive with honeycomb technology and may offer significant operational benefits as well. 6 |