Cost-effective low NOx firing
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BOILER SERVICE SOLUTIONS Low NOx Concentric Firing System (LNCFS™) Alstom’s Low NOx Concentric Firing System (LNCFS™) maximises the NOx reduction capabilities of existing tangential coal firing systems while keeping unit modifications to a minimum. Cost-effective low NOx firing For tangentially fired units As the leader in low NOx firing systems, Alstom has over 300 units totalling well over 100,000 MW of LNCFS™ system experience. The LNCFS™ firing system design is very flexible. There are three basic system configurations: LNCFS™ system levels I, II and III. Retrofits for any unit can range from simple to complex, with a corresponding range in retrofit cost and NOx reduction efficiency. DESIGN FEATURES Various design features are carefully applied in a manner which tailors each system to meet the individual NOx reduction needs of the customer, while considering the specific furnace configuration and fuels fired. NOx reductions of over 65% can be achieved through the application of these coal combustion techniques. Bulk furnace staging Bulk furnace staging is a technique in which a portion of the combustion air, usually introduced with the fuel, is diverted away from the main combustion zone. This delays the air / fuel mixing process, reducing the oxygen available for NOx formation in the high temperature flame core where most NOx is formed. LNCFS™ firing system accomplishes bulk furnace staging through the use of two distinct design features: overfire air and concentric firing. Overfire Air (OFA) In this well-established NOx reduction technique, a portion of the secondary air is diverted from the main windbox and introduced above the main combustion zone. Currently, overfire air has been utilised in well over 300 retrofitted and new tangentially fired Alstom boilers since 1971. Overfire air can be introduced through the top of the existing windbox as Close-Coupled Overfire Air (CCOFA), or injected higher up in the furnace through dedicated air registers as Separated Overfire Air (SOFA). LNCFS™ system level I, the simplest option, uses CCOFA in the system design. LNCFS™ system level II uses SOFA, while the most aggressive LNCFS™ system level III incorporates both. Customer benefits • Depending upon the complexity of the LNCFS™ firing system retrofit, the unit configuration and fuel being fired, NOx emission reductions from 25% to over 65% can be achieved with minimal impact upon unit performance and efficiency © ALSTOM 2014. All rights reserved. Information contained in this document is indicative only. No representation or warranty is given or should be relied on that it is complete or correct or will apply to any particular project. This will depend on the technical and commercial circumstances. It is provided without liability and is subject to change without notice. Reproduction, use or disclosure to third parties, without express written authority, is strictly prohibited. Photo credits: © ALSTOM 2014. All rights reserved. Printed on environmentally friendly paper. • The flexibility of the LNCFS™ system design permits the most cost-effective, state-of-the-art, low NOx firing technology available

BOILER SERVICE SOLUTIONS LOW NOx CONCENTRIC FIRING SYSTEM (LNCFS™) DESIGN FEATURES Concentric Firing System (CFS™) This is an Alstom patented design in which a portion of the secondary air admitted in the main firing zone is diverted away from the coal stream toward the furnace waterwall tubes. This delays fuel jet entrainment of secondary air during the critical initial coal devolatilisation stage of the combustion process. In addition to NOx reduction, the offset air maintains an oxidising atmosphere along the furnace walls, which can inhibit lower furnace waterwall corrosion. Rapid coal...