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Show Where burner-only retrofits make sense in our refinery NOx reduction technology mix, we have gone for the latest natural-draft, fuel-staged, self-recirculated ultra low NO! burners. These burners also have provision for steam augmentation, if needed. To date, we have retrofitted about a half dozen small "Rule 11 ~6 furnaces" with more burner-only retrofits to come in the next phase . Preliminary results at the time of writing this paper look good. In compliance tests, we have achieved NOx emissions well below the .f0 ppm limit of Rule 11 ~6 on refinery fuel gas without steam injection. An up-to-the-minute review and statistical update on performance will be provided in the oral presentation . To date, we have installed six selective catalytic reduction flue gas treatment plants connected to eleven combustion sources. including process furnaces. utility boilers. and gas turbines, with and without air preheat. with more to come in the next phase. These include SCRs that utilize both aqueous and anhydrous ammonia and operate at both conventional and low flue gas temperatures. Preliminary results at the time of writing look good. It appears that NOx reductions of 90 percent are achievable. An up-to-the-minute review and statistical update on performance will be provided in the oral presentation. Earlier. we pointed out that. in comparison with the Japanese experience. in refinery process furnaces the possibility of hydrocarbon leaks and subsequent fires introduces another design concern not present in stationary power generation . This reality was emphasized for us when. upon start up of one of our units. a tube rupture and fire destroyed the SCR catalyst charge. providing us with unwanted experience with catalyst replacement. The commercial implication of this experience is that refiners will need spare charges of catalyst available for SCRs installed on process heaters. This also means that refiners will be particularly receptive to module standardization by the catalyst suppliers; e.g., lxlum. to assist the refining industry in future replacements by minimizing catalyst storage requirements. Summary Countless interactions with our industrial colleagues and extensive experience leading up to our own projects at Chevron's El Segundo Refinery and elsewhere have led us to several broad conclusions. A refinery NO! reduction project is a complex undertaking. particularly if concurrent attainment of other goals such as re-instrumentation or fuel gas clean up proves to be either attractive or necessary. The first step in a NOx reduction project is to define the problem by comparing a complete emissions inventory with the emissions reduction goal. The nen step is to examine all the candidate NOx reduction technologies and determine the least cost mix to achieve the goal. Detailed site specific analyses of the various NOx reduction technology alternatives and costs is a difficult but worthwhile task. You will probably need a well qualified contractor to assist you in carrying out this step and. since you will certainly need installation assistance. it mates sense to involve a contractor at the scoping stage. Based upon Chevron and other experience, we have concluded that an optimized technology mix for refinery NO! reduction includes mainly fuel switching (no oil firing); natural-draft. fuel-staged, self-recirculating ultra low NO! burners; and selective catalytic flue gas treatment plants with commonly ,ized cataly,t modules. An optimized technology mix can produce compliance cost reductions up to 20 percent or more compared 'With the "all SCR" alternative . Finally. working with the contractor to evaluate and recycle post-installation results is probably the most important step. Evaluating" compliance" does not involve merely a snapshot in time but rather encompasses all aspects of statistical process control and includes recycling results in a continuous improvement process. 6 |
