METHANE de-NOX FOR UTILITY PC BOILERS

Abstract

The project seeks to develop and validate a new pulverized coal combustion system to reduce utility PC boiler NOx emissions to 0.15 lb per million Btu or less without post-combustion flue gas cleaning. Work during previous reporting periods completed the design, installation, shakedown and initial PRB coal testing of a 3-million Btu/h pilot system at BBP's Pilot-Scale Combustion Facility (PSCF) in Worcester, MA. Based on these results, modifications to the gas-fired preheat combustor and PC burner were defined, along with a modified testing plan and schedule. A revised subcontract was executed with BBP to reflect changes in the pilot testing program. Modeling activities were continued to develop and verify revised design approaches for both the Preheat gas combustor and PC burner. Reactivation of the pilot test system was then begun with BBP personnel. During the previous reporting period, reactivation of the pilot test system was completed with the modified Preheat gas combustor. Following shakedown of the modified gas combustor alone, a series of successful tests of the new combustor with PRB coal using the original PC burner were completed. NOx at the furnace exit was reduced significantly with the modified gas combustor, to as low as 150 ppm with only 36 ppm CO (both corrected to 3% O2). Concurrent with testing, GTI and BBP collaborated on development of two modified designs for the PC burner optimized to fire preheated char and pyrolysis products from the Preheat gas combustor. During the current reporting period, one of the two modified PC burner designs was fabricated and installed in the pilot test facility. Testing of the modified pilot system (modified gas combustor and modified PC burner) during the quarter included 38 tests with PRB coal. NOx reduction was significantly improved to levels as low as 60-100 ppmv with CO in the range of 35-112 ppmv without any furnace air staging.