Nox Control For Utility Boiler Otr Compliance

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Download or read book NOx Control for Utility Boiler OTR Compliance written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Babcock & Wilcox Power Generation Group (B & W) and Fuel Tech, Inc. (Fuel Tech) teamed to evaluate an integrated solution for NO(subscript x) control comprised of B & W's DRB-4Z{reg_sign} low-NO(subscript x) pulverized coal (PC) burner technology and Fuel Tech's NO(subscript x)OUT{reg_sign}, a selective non-catalytic reduction (SNCR) technology, capable of meeting a target emission limit of 0.15 lb NO(subscript x)/106 Btu. In a previous project sponsored by the U.S. Department of Energy (DOE), promising results were obtained with this technology from large-scale testing in B & W's 100-million Btu/hr Clean Environment Development Facility (CEDF) which simulates the conditions of large coal-fired utility boilers. Under the most challenging boiler temperatures at full load conditions, NO(subscript x) emissions of 0.19 lb/106 Btu were achieved firing Powder River Basin coal while controlling ammonia slip to less than 5 ppm. At a 40 million Btu/hr firing rate, NO(subscript x) emissions were as low as 0.09 lb/106 Btu. Improved performance with this system was proposed for this new program with injection at full load via a convective pass multiple nozzle lance (MNL) in front of the superheater tubes or in the convective tube bank. Convective pass lances represent the current state-of-the-art in SNCR and needed to be evaluated in order to assess the full potential of the combined technologies. The objective of the program was to achieve a NO(subscript x) level below 0.15 lb/106 Btu (with ammonia slip of less than 5 ppm) in the CEDF using PRB coal and B & W's DRB-4Z{reg_sign} low-NO(subscript x) pulverized coal (PC) burner in combination with dual zone overfire air ports and Fuel Tech's NO(subscript x)OUT{reg_sign} System. Commercial installations of B & W's low-NO(subscript x) burner, in combination with overfire air ports using PRB coal, have demonstrated a NO(subscript x) level of 0.15 to 0.2 lb/106 Btu under staged combustion conditions. The proposed goal of the combustion system (no SNCR) for this project is a NO(subscript x) level at 0.15 lb/106 Btu. The NO(subscript x) reduction goal for SNCR is 25% from the low-NO(subscript x) combustion emission levels. Therefore, overall NO(subscript x) emissions would approach a level of 0.11 lb/106 Btu in commercial installation. The goals of the program were met. At 100% load, using the MNL for very low baseline NO(subscript x) (0.094 to 0.162 lb/106 Btu depending on burner stoichiometry), an approximately 25% NO(subscript x) reduction was achieved (0.071 to 0.124 lb/106 Btu) while maintaining NH3 slip less than 6.4 ppm. At 60% load, using MNL or only wall-injectors for very low baseline NO(subscript x) levels, more than 30% NO(subscript x) reduction was achieved. Although site specific economic evaluation is required for each unit, our economic evaluation of DRB-4Z{reg_sign} burner and SNCR for a 500 MW{sub e} plant firing PRB shows that the least cost strategy is low-NO(subscript x) burner and OFA at a cost of $210 to $525 per ton of NO(subscript x) removed. Installation of SNCR allows the utilities to sell more NO(subscript x) credit and it becomes economical when NO(subscript x) credit cost is more than $5,275 per ton of NO(subscript x).