METHANE de-NOX for Utility PC Boilers

Abstract

During the current quarter, pilot-scale testing with the modified air nozzle version of the PC burner was completed with PRB coal at the Riley Power Inc. (RPI) test facility. A total of 8 different burner configurations were tested utilizing various burner air nozzle arrangements in place of the burner air channels. It was found that with the arrangements tested, a stable flame could not be maintained at coal feed rates above 100 lb/h. While it is felt that the air nozzle approach can ultimately be used effectively, in the interest of holding to the current project schedule it was decided to proceed with the balance of the project using the air channel design. The pilot-scale PC burner was therefore restored to the air-channel configuration and benchmark testing with PRB coal to confirmed previous operating results. A series of tests was then conducted with PRB and West Virginia caking coal to evaluate modifications to the gas combustor configuration and operation for improved performance with caking coal. Continuous operation was achieved with caking coal up to 50 lb/h vs. the full load target of 150 lb/h. Impingement and deposition of partially devolatilized coal occurred at various points within the combustor when the caking coal feed was increased above 50 lb/h. The 100 MMBtu/h commercial-scale prototype design was continued with coal burner design input from both RPI and VTI. Based on typical burner installation layout considerations, it was decided that the preheat combustor should be oriented horizontally on the axial centerline of the coal burner. Accordingly, the pilot gas combustor was changed to this orientation so that the pilot results with caking coal will be directly applicable to the preferred 100 MMBtu design. Testing with caking coal in the horizontal pilot combustor achieved feed rates up to 126 lb/h, although some deposition and LOI issues remain. Several promising approaches to further improve operation with caking coal were identified. NOx results with caking coal are promising, with NOx as low as 150 ppmv at exit oxygen levels of 4% and higher. The 100 MMBtu/h commercial-scale prototype design is nearing completion. Design of the caking coal version of the unit continues with additional pilot testing in support of this design expected. GTI and RPI are expediting the fabrication of the 100 MMBtu/h PRB unit in order to start testing in early- to mid-December. Inspection and repair of the 100 MMBtu/h Coal Burner Test Facility (CBTF) is nearing completion. As of mid-September, this activity was 95% complete.