Coal Fired Boilers - Secondary Air for Low NOx Burners Application Brochure

The Kurz K-Bar 2000B Multi-Point Insertion Mass Flow Meter system replaces conventional Venturi/Dp systems to eliminate the pressure loss and increase the air fl ow capacity required for proper operation of Low NOx burnersPOWER GENERATION SECONDARY AIR FOR LOW NOx BURNERScomplex technology MADE SIMPLEA P P L I C A T I O N N O T E Secondary Air Flow OverviewThe need for accurate, repeatable & reliable combustion air measurements in power generation plants is critical to effi cient operation and safety throughout the entire facility and processes. Accurate secondary air fl ow measurement to the burners is critical for maintaining the proper air to fuel ratio, result-ing in more complete and stable combustion, better performance and lower emissions. Coal-fi red power plant applications pose a number of challenges to obtaining these critical fl ow measurements including large ducts, limited metering runs, poor velocity and temperature profi les, vibration and high temperatures. Customer Application and Performance IssuesA large EP&C fi rm in the Northeast had a contract to install Low Nox burners at a Coal Fired Power Plant in the Southeast. The Power Generating Station had two 650 Megawatt coal-fi red boilers in operation. In order to help meet increasing electricity demands, the company planned an expansion that would add a third unit to the facility. However, environmental regulations required that the emissions from the existing plant be lowered before the new plant could be built. The fi rst phase of expansion consisted of upgrading Unit 1 and 2 Boilers with Low NOx burners to reduce their emissions.The challenge for the EP&C fi rm was that Low NOx burners need a higher air pressure/fl ow in order to operate effectively and achieve lower emissions. But in this application, the secondary air ducts were originally built with Venturi/Dp air fl ow measurement systems. The original Venturis were used to create a pressure drop which is then measured by a Dp transmitter to calculate the secondary air fl ow rate to the burners. Therefore, the EP&C fi rm needed to remove the Venturis so that the new Low NOx burners would have suffi cient pressure/fl ow to operate properly. Once the Venturis were removed the EP&C fi rm had the challenge of fi nding a technology to measure the low pressure, low velocity and high temperature secondary air fl ow. The Kurz Thermal Mass fl ow metering system was the only technology that would operate in this ap-plication.The Kurz SolutionThe key to achieving Low NOx burner performance and lower emissions was to remove the Venturi/Dp system and install Kurz Multi-Point K-Bar 2000B Velocity Probes and Adam 155 Flow Computer/Transmitter measurement system. With the secondary air ducts measuring 13’ high by 21’ wide, each system consisted of (4) K-Bar 2000B Probes each with (4) velocity sensors to provide a (16) sensor velocity array, equally spaced across the duct, for a total of (16) velocity sensor readings. Benefi ts of the Kurz Solution• Virtually no pressure loss• Reduced Emissions from proper Low NOx Burners performance• Extremely Low Main-tenance even Under Harsh Operating Condi-tions • Accurate, Repeatable and Reliable readings in Low Velocity, High Turndown applications Power Generation: Coal Fired BoilersSecondary Air Flow for Low NOx Burners PAGE 2 DCN 364040 Copyright © 2009 Kurz Instruments Inc.Performance Results with the Kurz SolutionDue to the outstanding low velocity performance of the Kurz thermal mass sensors, the scope of the project was expanded to include Thermal Mass fl ow meter solutions for Main Primary Air and Tempering Air ducts along with the Primary Air to the mills, Auxiliary Air and the Seal Air on the Pulverizer Ball Mills. A total of 200 Kurz thermal mass fl ow sensors were installed throughout the entire facility. As a result of the Kurz K-Bar 2000B Multi-Point System in this application, the plant was able to:• Remove the Venturis and eliminate the system pressure drop• Improve Measurement Accuracy, Repeatability, Turndown and confi -dence in the Air Flow Measurement• Obtain the proper Air to Fuel Ratio required for proper operation of the Lo Nox burner• Eliminate maintenance time required to keep the Venturi/Dp system operating properly• Lower the plant emissions and pursue approval to build Unit 3About Kurz InstrumentsKurz Instruments has maintained a reputation for designing and manufactur-ing Thermal Mass Flow Transmitters for industrial air and gas fl ow applica-tions. For more than 30 years, our entire team has provided solutions to our customers most demanding and diffi cult applications. Kurz products are used in a wide variety of industrial applications including combustion air, aeration air fl ow and digester gas, nuclear power plants, pump protection, fl are stack monitoring and compressed air, to name only a few.Kurz Instruments, Inc.2411 Garden RoadMonterey, CA 93940 800-424-7356 Toll Free Phone831-646-5911 Local Phone831-646-8901 Faxsales@KurzInstruments.comwww.KurzInstruments.comPAGE 3 DCN 364040 Copyright © 2009 Kurz Instruments Inc. TOP: The Venturi section of the secondary air ductCENTER: The new duct section where the Venturis were removed to elimi-nate the pressure drop for proper operation of the Low Nox burners BOTTOM: The Kurz K-Bar 2000B Probes installed at the base of the secondary air duct