OCR Text |
Show APPLICATION EXPERIENCE ON A COAL FIRED CFB BOILER The THERMAL DENOX System has been operating since 1989 at the Ultrasystems Rio Bravo Jasmin Plant located in Bakersfield, California. The circulating fluidized bed boiler fires up to 394 MBTU/hr of coal, produces 290,000 lb/hr steam @ 1750 psia & 955 OF, and has an untreated NOx emission of 234 PPMv at design conditions, or 257 PPMv dry. In addition to the THERMAL DENOx system for NOx reduction, the Jasmin plant includes a multiclone and a baghouse for particulate removal. JASMIN THERMAL DENOX SYSTEM DESIGN The Jasmin THERMAL DENOx system was designed and guaranteed to achieve an outlet emissions below 39.4 Lb NOx/hr. For the design case with an untreated value of 234 PPMv at conditions (257 PPMv dry, or .377 Lb NOx/MBTU), a 74% NOx reduction was required to meet the limit of 39.4 Ib NOx/hr leaving the stack (68 PPMv dry, or 0.10 Lb NOx/MBTU). The Jasmin boiler design conditions were for operations at essentially 100% base load for perhaps 300 day runs. The steady operation, and the low fluctuation of fluegas temperature and composition allowed for a relatively simple choice for injection configuration. Installation of nozzles downstream of the cyclone provided sufficient residence time for the mixing and reactions to take place. The design called for one 12,000 Gallon anhydrous ammonia storage providing 27 days storage and a 15.3 KW ammonia vaporizer providing ammonia vapor to the injectors. The design specified one 143 BHP air compressor to deliver 1170 SCFM air for use as a carrier to assist in mixing of the ammonia with the NOx. The design also includes separate controls for the air and ammonia. Air carrier flow is controlled by a pressure control valve as a function of boiler load. Ammonia flow is controlled by a flow control valve as a function of steam production, fl uegas 02 concentration and temperature. Ammonia trim is provided via a NOx signal from the stack. JASMIN PROCESS PERFORMANCE The data tabulated below were provided by Ultrasystems and show data taken December 3, 6, & 9, 1991. The data shows that NOx reduction down to values below 39.4 Lb/hr NOx (68 PPMv dry), and even approaching a lower value of 50 PPMv dry, was achievable with Ammonia Injection at rates between 45 and 65 Lb/hr. The THERMAL DENOx process achieved roughly 77% NOx reduction for these conditions in December at Jasmin. RIO BRAVO JASMIN OPERATING DATA DATE December 91 3 6 9 Load % 97 97 97 Peak NOx @ Stack Lb/hour 36.2 35.2 34.7 PPMv wet 51.5 48.0 47.8 PPMv dry 56.7 52.8 52.8 NH3 Use Lb/hour 45.3 64.7 52.9 Mole Ratio NH3:NOxin .76 . 1.0 .84 % DENOx 7 S. 6 76.3 76.6 |